Open access peer-reviewed chapter

Renin-Angiotensin System MicroRNAs, Special Focus on the Brain

Written By

Jose Gerardo-Aviles, Shelley Allen and Patrick Gavin Kehoe

Submitted: May 24th, 2016 Reviewed: November 28th, 2016 Published: July 12th, 2017

DOI: 10.5772/67080

Chapter metrics overview

1,236 Chapter Downloads

View Full Metrics


MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression with important roles in cancer, cardiovascular and neurological disorders. Present in the brain, they play numerous regulatory roles shaping the proteome in an orchestrated manner with other non-coding RNAs. An independent brain-specific renin-angiotensin system (RAS) exists that is subject to miRNA remodelling. The brain RAS regulates cerebral blood flow and electrolytic balance and is involved in neurotransmitter signalling and cognitive processes. Circulating microRNAs allow interaction between systemic and local RAS in the heart and the brain. Their screening and manipulation may be valuable towards understanding pathophysiology and development of treatments for various systemic and central nervous system diseases.


  • non-coding RNAs
  • microRNAs
  • brain renin-angiotensin system
  • cerebrovascular disease
  • circulating microRNAs
  • biomarkers

1. Introduction

High blood pressure, leading to cardiovascular and cerebrovascular disorders, is the principal cause of morbidity and mortality worldwide [13]. The renin-angiotensin system (RAS) is a major regulator of cardiovascular function and pharmaceutical compounds targeting the RAS are frontline treatments to control high blood pressure [4, 5]. In addition, lifestyle risk factors such as obesity, insulin resistance, high alcohol and salt intake and ageing promote the development of hypertension through epigenetic mechanisms [69]. These mechanisms have attracted attention because of their reversibility by environmental and lifestyle modifications, making them important in the detection and treatment of multifactorial diseases such as hypertension [7, 10].

Some of those epigenetic modifications are mediated by miRNAs, defined as single-stranded, non-coding RNA sequences approximately 21–23 nucleotides in length, expressed under physiological and pathological conditions [11, 12]. Deletion of complexes involved in miRNA biogenesis resulted in deleterious and non-viable phenotypes, highlighting their necessary involvement in the cellular development and differentiation [13, 14]. To date, 28,645 miRNAs have been reported in miRbase, a widely used resource for miRNA cataloging and nomenclature [15]. As epigenetic regulators of gene expression, functions of miRNAs include RNA degradation, inhibition of protein expression, regulation of methylation and histone modification on DNA [12, 14, 16]. miRNAs perform these functions by complementary base pairing to the target mRNAs through a seed-pairing region of 6–8 nucleotides at the 5′ end of the miRNA. They also interact with other non-coding RNAs and mediate proteome remodelling. Non-coding RNAs represent 98% of the genome, comprising transfer and ribosomal RNA, small nuclear (snRNA) and nucleolar RNA (snoRNA), small interference RNA (siRNA), Piwi-interacting RNA (piRNA) and long non-coding RNAs (lncRNA) [14, 17, 18].

Dysregulation of miRNAs is associated with cancer, cardiovascular and neurodegenerative disorders. The RAS, with important signalling roles in numerous organs and regulatory pathways and being subject to miRNA-mediated remodelling, is a potential factor in many disorders. Thus, the presence of miRNAs that have the capacity to shift the balance between prominent and deleterious functions of the RAS to beneficial roles is interesting, particularly new advances in methods that allow the detection of circulating miRNAs. Exosomes and their role in cellular transport provide a source for miRNA profiling and the presence of miRNAs in the peripheral circulation suggests that they work in an autocrine, paracrine and also endocrine manner, allowing widespread distribution of miRNAs through the entire body. Therefore, screening of miRNA in biological fluids like a serum and cerebrospinal fluid is relevant for an understanding of normal function as well as pathophysiology with a view to potential novel treatments for the disease.

The discovery of local independent but interacting RAS systems, including the brain, which also interacts with systemic RAS [3], has helped to change the original view that the RAS was solely an endocrine system important in regulating blood pressure, electrolytic homeostasis, vascular injury and repair [19]. The brain RAS discussed here (Figure 1) is multifunctional including regulation of cerebral blood flow, electrolyte balance, neurotransmitters, learning and memory, many of which may be associated with certain neurological disorders [20, 21].

Figure 1.

The renin-angiotensin system (RAS) and its components. This schematic depicts angiotensin ligands, receptors and the main enzymes involved; other peptidases and cathepsins also participate although to a lesser extent. All of the components of the RAS are present in the brain. RAS has two main axes: the pressor axis (tending towards an increase in blood pressure) comprising Ang II, ACE and AT1Rs and the counter-regulatory axis comprising Ang(1–7), ACE2 and MasR. Angiotensinogen is a substrate for renin to produce angiotensin I (Ang I), which is the inactive precursor of all angiotensin peptides. Conversion of Ang I to its most active ligand in the pressor axis, angiotensin II (Ang II), results from ACE-mediated hydrolysis [22]. Ang II is then sequentially converted to angiotensin III (Ang III) and angiotensin IV (Ang IV) by aminopeptidase A (APA) and aminopeptidase N (APN) respectively, which can be further cleaved by carboxypeptidase P (CP) and prolyl oligopeptidase (PO) to form angiotensin 3–7 (Ang3–7). Alternatively, Ang II can be converted, via the counter-regulatory axis to angiotensin 1–7 (Ang1–7) by carboxypeptidase P (CP) or ACE2, while both angiotensin A and Ang1–7 can be converted to alamandine by an ACE-mediated decarboxylation reaction [2227]. Notably, angiotensin ligands acting on AT4R (also called insulin-regulated aminopeptidase (IRAP)) can have agonist or antagonist effects depending on whether or not they bind in the IRAP peptidase domain.


2. Biogenesis and function of miRNAs

Canonical miRNA biogenesis starts with transcription of the primary miRNA sequence by RNA polymerase II and III [14]. Approximately half (52%) of human miRNAs are located in intergenic regions, 40% in intronic and 8% in exonic [28]. Intergenic miRNAs are independently expressed through promoter elements; yet related miRNAs that often have overlapping targets can be located on different chromosomes and expressed under different conditions. Intronic and exonic miRNAs that are clustered within 50 kilobases from each other show similar expression, while those spaced further apart tend not to [29]. However, there are some exceptions. Some miRNAs separated by more than 50 kilobases retain high correlation, likely as a result of co-expression [30]. The differential localization and expression of miRNAs suggest an evolutionary response to environmental insults and specific cell responses, a theory supported by observed higher numbers of miRNAs expressed in organisms of higher complexity [3133].

Figure 2A–F summarizes the process of miRNA biogenesis. Primary miRNAs are cleaved in the nucleus by a nuclear microprocessor complex comprised of the RNase III endoribonuclease DROSHA and its double-stranded RNA-binding protein DGCR8—DiGeorge Critical Region 8, Figure 2A [34]. This cleavage by DROSHA/DGCR8 produces a 60 nucleotide stem-loop structure with a 3′ overhang, the pre-miRNA [11, 34, 35]. The primary miRNA can also be further subjected to RNA editing by ADARs (adenosine deaminases acting on RNA) that modify adenosine to inosine producing miRNA isoforms called isomiRs [36].

Figure 2.

MicroRNA biogenesis and function. (A) Primary miRNAs are cleaved in the nucleus by the RNase III endoribonuclease DROSHA and DGCR8. (B) Once the primary miRNA is cleaved, the nuclear transport receptor exportin 5 binds the 3′ overhang structure of the pre-miRNA to export it to the cytoplasm. (C) The RNase III enzyme Dicer and TRBP and PACT target the pre-miRNA through the 3′ overhang, converting it into mature miRNA, liberating a duplex nucleotide structure with two nucleotides protruding at the 3′ end. (D) The guide strand is loaded into the RNA-induced silencing complex (RISC), and the passenger strand is degraded by RNases. (E) Complementary pairing with the seed region to mRNAs determines target binding and guides argonaute proteins to stop translation. Accumulation of untranslated mRNA in the cytoplasm allows recruitment of members of the GW182 protein family. (F) Deadenylase complexes cause destabilization of the transcript and further degradation by RNase activity.

Exportin 5 allows export of the pre-miRNA to the cytoplasm, Figure 2B [36], where Dicer and substrate stabilizing binding partners, TRBP (trans-activation response RNA-binding protein) and PACT (protein activator of RNA‐activated protein kinase) facilitate conversion into mature miRNA, Figure 2C [12, 14]. Two strands result from the unwinding of the duplex, the guide (3p) and passenger (5p) strands. Most of miRNA effects are mediated by the 3′ form; the 5′ form comprises <10% of all miRNA reads in humans [36]. The guide strand is loaded into the RNA-induced silencing complex (RISC) and the passenger strand is degraded by RNases, Figure 2D. IsomiRs can also be produced at this step by trimming and capping of the mature miRNA.

Non-canonical miRNA biogenesis is independent of DROSHA/DGCR8 processing in the nucleus. Such biogenesis arises if an intron is spliced lacking the sequences ordinarily flanking the stem region of a primary miRNA and it is of sufficient size to generate a pre-miRNA and it can be exported to the cytoplasm and further processed as a pre-miRNA to form a mirtron. Alongside mirtrons, other RNA sequences derived from transfer RNA and small nucleolar RNA are loaded into an RISC complex and act as miRNAs [13, 14, 29].

The RISC is a ribonucleoprotein complex that mediates mRNA degradation, destabilization or translational inhibition, whatever the biogenesis mechanism and comprises the miRNA guide strand and argonaute proteins, Figure 2E. The complementary base pairing of the miRNA seed region (2nd to 8th position on the 5′ end) to mRNAs determines target binding and guides argonaute proteins [28, 37, 38]. miRNA levels are dependent on argonaute proteins [39, 40] that are also present in the nucleus and currently, only miRNA-29b has been shown to translocate and localize in the nucleus [14, 39, 41]. In humans, argonaute 2 (also called eukaryotic translation initiation factor 2C) cleaves target mRNAs [29] but can also block other translation initiator factors and ribosomal subunits [42].

After pairing of the miRNA seed region, protein translation can be inhibited, Figure 2E. Accumulation of untranslated mRNA in the cytoplasm allows argonaute 2 to recruit members of the GW182 protein family, which are enriched in cytoplasmic areas called processing bodies (p-bodies) [42]. Here, the mRNA is destabilized by deadenylase complexes and further degraded by RNases [4345]. Finally, the effect miRNAs have on protein or mRNA levels depends on the position where the miRNA binds and five different classes of miRNA binding have been determined [12, 46, 47]. Most miRNA effects are mediated by binding at the 3′ UTR of mRNA and further processing as described previously, non-canonical binding sites represent <1% [48].


3. MicroRNAs as autocrine, paracrine and endocrine molecules

miRNAs not only shape the intracellular proteome within specific cell types in response to microenvironment stimuli and cues, but can also mediate intercellular effects by means of nanotubes, exosomes and binding proteins, all mechanisms of intercellular communication [49]. Moreover, extracellular vesicles, including exosomes, microvesicles and apoptotic bodies, also participate in paracrine and endocrine signalling, as well as an intercellular transfer of miRNAs [5052]. Exosomes, in particular, which are nanovesicles derived from endosomes are involved in cell-to-cell communication [53], contain significant amounts of miRNAs and are resistant to changes in temperature, pH and the effect of RNases making them reliable sources for screening [51, 54, 55]. miRNAs are transported by RNA-binding proteins and are taken up into intraluminal vesicles during the formation of multivesicular bodies in endosomes [56]. Upon fusion of the endosome to the plasma membrane, the intraluminal vesicles are released as exosomes and due to their lipid composition and size, they can easily transfer genetic material across lipid membranes [55, 56]. Several miRNAs are transferred in vivo and in vitro between fibroblasts, cardiomyocytes, human umbilical endothelial cells, mesenchymal stem cells, cardiac and cerebral endothelial cells [57, 58], while atheroprotective communication has been found between endothelial and smooth muscle cells through miRNAs [59].

miRNA transfer both propagates deleterious effects and helps recover cells from insults and prevent apoptosis. For example, miR-133 is increased in people with cardiovascular disease and is transferred through exosomes from multipotent mesenchymal stromal cells to astrocytes and neurons that promote recovery after stroke [6063]. Furthermore, remote ischaemic conditioning, a technique of small cycles of ischaemia/reperfusion in distal extremities, was protective for cardiac and cerebrovascular effects in animal experiments and human clinical trials, with effects mediated by miRNAs such as miR-1 [6469].

Exosomal circulating miRNAs have many properties that arguably make them ideal biomarkers, including their presence in peripheral blood, detection in many biological fluids, their stability in RNase-rich body fluids and their tissue-specific expression patterns. These have been described in cardio-cerebrovascular disorders, diabetes, dyslipidemia and neurodegenerative disorders [1, 7076]. Furthermore, human exosomes can be used therapeutically as a gene delivery vector to provide cells with heterologous miRNAs [53].


4. Regulation of RAS by associated microRNAs

Given that there is further discussion of the biochemical functions of the RAS in other chapters, the discussion henceforth will focus on some of the most important components of the brain RAS and the miRNAs targeting them.

Since the vital function of the brain results in high physiological demands (i.e. requiring 20% of total cardiac output and a 10-fold higher oxygen and energy demand than other tissues), it requires strict coordination between blood flow and neuronal activity, a phenomena known as functional hyperaemia [77]. Cerebral blood flow is regulated by vasomotor, metabolic and neurogenic mechanisms, but can be modulated by vasoconstrictors such as Ang II and endothelin, vasodilators such as bradykinin, adenosine and other angiotensin ligands, while blood vessel capacity may be reduced or impeded by plaques of cholesterol, amyloid or fibrotic deposits.

Analysis by TargetScan [48], a software that predicts miRNA binding sites, suggests that 368 different miRNA families target RAS elements, the majority of which share transcripts. Table 1 summarizes the total number of miRNAs and unique miRNAs with respect to RAS elements, as they have other targets outside the RAS. Angiotensin 4 receptor (also known as AT4R or IRAP) has 252 miRNA families associated with it, making it the highest amongst the RAS and approximately fivefold and threefold as many as that for arguably its better known receptors AT1R and AT2R. Notably, 88% of IRAP-associated miRNAs also regulate other RAS transcripts, suggesting its susceptibility to changes elsewhere in the RAS. In particular, IRAP has 28 miRNA families exclusively associated with it (also the most for RAS components), hinting at having high functional importance. Indeed, aminopeptidase B and dipeptidyl peptidase, necessary for Ang IV conversion, do not have exclusive miRNAs and thus may be subject to many regulatory effects.

RAS element Gene symbol Total miRNA families Unique miRNA families
Angiotensinogen AGT 85 11
Angiotensin 1 receptor (AT1R) AGTR1 46 1
Angiotensin 2 receptor (AT2R) AGTR2 78 5
Angiotensin 4 receptor (AT4R/IRAP) LNPEP 252 28
Mas receptor MAS1 5 1
Angiotensin converting enzyme ACE 59 4
Angiotensin converting enzyme 2 ACE2 54 4
Renin REN 21 2
Neprilysin MME 151 8
Aminopeptidase B RNPEP 29 0
Aminopeptidase N ANPEP 31 4
Aminopeptidase A ENPEP 158 13
Dipeptidyl peptidase DPP3 32 0

Table 1.

miRNA families targeting RAS elements.

The total number of miRNAs represents miRNA families with binding sites at the 3′UTR region based on TargetScan [48]. Unique miRNAs are those considered solely with respect to other RAS elements.

A more in-depth examination of RAS-associated microRNAs, according to their functional impact in the RAS physiology is shown in Table 2. MiR-3163 targets the greatest number of RAS transcripts (N = 8) and may provide an over-arching level of regulation for the pathway as a whole, for example, in response to an external stimulus. miR-125-5p with five targets in common may function in a similar way, particularly since two of the targets are principal enzymes in RAS biochemistry. Yet, they make an ideal combination to block Ang II/AT1R and Ang IV/AT4R pathways and also shift the conversion of Ang I to Ang (1–7) via neprilysin and other peptidases to act on MasR.

RAS components microRNA families in common
AGTR2 DPP3 LNPEP MME 1 miR-17-5p/20-5p/93-5p/106-5p/519-3p
ACE2 ENPEP LNPEP MME 3 miR-9-5p, miR-200-3p/429, miR-942-5p
AGTR2 LNPEP MAS1 1 miR-23-3p
ENPEP LNPEP MME 17 miR-26-5p, miR-30-5p, miR-132-3p/212-3p, miR-194-5p, miR-204-5p/211-5p, miR-216-5p, miR-376-3p, miR-376c-3p, miR-378-3p, miR-450b-5p, miR-518d-5p/519-5p, miR-522-3p, miR-580-3p, miR-653-5p, miR-1269, miR-3942-5p, miR-4766-3p
ACE2 ENPEP LNPEP 4 miR-374-5p/655-3p, miR-543, miR-4424, miR-1306-5p
ACE2 LNPEP MME 3 miR-374a-3p, miR-3194-3p, miR-5691
DPP3 LNPEP MME 5 miR-146-5p, miR-183-5p.1, miR-589-5p, miR-876-5p, miR-2355-5p
ACE2 DPP3 LNPEP 1 miR-329-3p/362-3p
ACE2 ENPEP MME 1 miR-140-3p.1
ENPEP LNPEP 17 miR-9-3p, miR-19-3p, miR-29-3p, miR-34b-5p/449c-5p, miR-105-5p, miR-122-5p, miR-144-3p, miR-320, miR-323-3p, miR-323b-3p, miR-382-3p, miR-494-3p, miR-514a-5p, miR-515-5p/519e-5p, miR-642a-5p, miR-3146, miR-5579-3p
DPP3 ENPEP 1 let-7-5p/98-5p
MAS1 1 miR-143-3p
ENPEP 13 miR-133, miR-142-3p.2, miR-219-5p, miR-371a-3p, miR-409-5p, miR-451, miR-496.1, miR-508-3p, miR-526b-5p, miR-877-5p, miR-1185-5p, miR-5094
ACE AGTR1 DPP3 1 miR-34-5p/449-5p
AGTR1 1 miR-1-3p/206

Table 2.

A summary of the subgroups of miRNAs according to their functional effect in the RAS.

From 164 combinations of overlapping targets and miRNAs in common, only 14 are included here, 12 which if increased would favour vasoconstriction and 2 would increase vasodilation. Others tend to influence multiple RAS pathways, an example, miR-3163, is given at the bottom of the table. miRNAs in bold are described further in the text.

In terms of RAS function, a group of microRNAs that can shift a predominant role of, for example, the Ang II/AT1R axis to opposing axes such as Ang(1–7)/MasR or Ang IV/AT4R could change cerebral blood flow, response to hypoxia and perhaps influence cognition and vice versa. Indeed, a panel of 17 miRNA families target aminopeptidase A and IRAP that could potentiate the formation of Ang IV (since aminopeptidase A converts Ang I and Ang II to Ang III, the Ang IV precursor for Ang IV). Thus, upregulation of those 17 miRNAs could modulate Ang III and IRAP to a greater extent than just one miRNA, such as miR-125. The net effect of reducing both ligand and receptor means that the function of the Ang IV/AT4R axis might be completely inhibited with likely deleterious effects on blood flow and cognitive performance. By contrast, downregulation of these miRNAs would increase the Ang IV/AT4R axis. The following section will discuss the effect of some specific miRNAs and their regulatory effects in RAS in the brain in health and in disease states.


5. miRNAs and RAS: cerebrovascular regulation and cognitive function

5.1. MiR-1/206

The miR-1/206 family has been suggested to exclusively target AT1R in the RAS; however, it has an estimate of 790 other transcripts regulating other systems [48]. MiR-1 and miR-206 are located in chromosomes 20 and 6, respectively and share homology in the seed region. An evaluation of biochemical, cardiovascular and performance indexes of aerobic exercise activity showed that some miRNAs were significantly increased. Specific correlations were found between miR-1, miR-133a and miR-206 and performance parameters, with miR-206 having the strongest positive correlation [78]. MiR-1 was also found to be decreased 1.4-fold in post-mortem cardiac tissue from acute myocardial infarction patients [79]. In contrast, elevated plasma miR-1 levels were reported to predict heart failure after acute myocardial infarction although they returned to basal levels after medication [80].

In conditions of hypoxia such as infarcts, oxygen/glucose deprivation or with ischaemia/reperfusion intervals, miR-1 is highly expressed [79, 80]. Under less stressful and non-life-threatening situations, miR-206 is transcribed [78], both of them targeting AT1R to decrease Ang II-mediated vasoconstriction and in doing so increasing the supply of oxygen and glucose to cells to prevent apoptosis.

MiR-1 overexpression inhibits contractility and proliferation of human vascular smooth muscle cells (VSMCs) in vitro in a negative feedback loop [81, 82]. MiR-1 is downregulated in VSMCs from spontaneous hypertensive rats and its overexpression in vivo inhibits the proliferation of VSMCs by targeting insulin-like growth factor 1 (IGF1) [83]. By contrast, miR-1 upregulation enhances angiogenic differentiation of human cardiomyocyte progenitor cells [84]. The opposite effects of miRNA in different cell types may be explained by its cell-specific expression. Indeed, even if the miRNA is expressed under physiological conditions, variations to this will depend on local gene expression in a time- and cell type-dependent manner.

Evidence of peripheral and central roles for miRNAs was seen in a transgenic mouse model of cardiac-specific overexpression where miR-1 levels were increased not only in the heart but also in the hippocampus and peripheral blood. Furthermore, the mice showed cognitive impairment by downregulation of brain-derived neurotrophic factor (BDNF), a target of miR-1 [85], providing strong evidence for a role in endocrine signalling and association between vascular disorders and cognitive impairment. Nevertheless, it is unlikely that the response depends exclusively on miR-1 and it is not known as to whether the associations are primary or secondary in nature.

Collectively, miR-1 may serve to support protective mechanisms to adapt to adverse hypoxic insults and remodel the proteome as a result. Indeed, as mentioned above, remote ischaemic conditioning showed a high correlation between ischaemia/reperfusion intervals and the levels of miR-1 in rats independent of BDNF mRNA and protein levels [69]. Hence, the miR-1/206 family is likely important in cardioprotection, prevention of stroke and consequently cognitive impairment. Already it is used in screening for myocardial infarction, monitoring and response to therapy and also has a tentative therapeutic use for increasing vasodilation and angiogenesis [86, 87].

However, a solitary miRNA or miRNA-target interaction, such as between miR-1/206 and AT1R, is unlikely to be able to explain a complete physiological response. Inherent properties between miRNA transcription, interactions between their targets, the timing of their expression and subcellular localization provide a more likely explanation. A panel of dysregulated miRNAs is likely to cause an imbalance in targets, proteins and pathways involved. Such a characteristic combination of altered miRNAs may be useful as diagnostic tools. For example, a diagnosis of cholangiocarcinoma can now be made with 100% accuracy in the presence of a 30-miRNA signature, three of them are useful for prognosis and monitoring and one of which has already entered a Phase I clinical trial as a potential treatment [8891].

5.2. MiR-143

The Mas receptor (MasR) has the lowest number of associated miRNAs, implying steady and tightly regulated homeostatic expression, although other post-transcriptional modifications are also likely to be involved in its regulation. In addition, miR-143 is exclusive to MasR in the RAS and interestingly, it has been found to be dysregulated in vascular disorders [92]. MiR-143 is enriched in cardiac stem cells before becoming localized to smooth muscle cells, including neural vascular smooth muscle cells (VSMC) in mice and its expression was found to be dependent on heartbeat rate in zebrafish [93, 94]. In human peripheral blood mononuclear cells, miR-143 was upregulated in patients with essential hypertension and decreased in aortic aneurysms [95, 96]. Previous studies have focused on other targets of miR-143 in hypertension, yet the potential effect of miR-143 via the MasR remains elusive. Due to the small number of miRNAs attributed to the regulation of MasR, fluctuations in just one of them might have a significant effect on MasR protein levels.

5.3. MiR-132/212

Ang II regulated the miR-132/212 family in hypertensive rats and humans [97, 98] and this family has been attributed with both cardiovascular and brain-specific properties [99103]. MiR-132/212 was initially thought to directly target AT1R with experimental studies demonstrating a prevalent effect in the RAS, but new advances and criteria in miRNAs have shown that the effect was due to various downstream second messengers of AT1R activation. miRNA-132/212 has multiple targets including Ang II and endothelin-1 (ET-1) signalling [99]. Thus, miRNA-132/212 might be relevant in hypoxic conditions to control the vasoconstrictor effects of Ang II and ET-1. Indeed, transplantation of pericyte progenitor cells from human adult vena safena (Bristol pericytes) induced pro-angiogenic activity in endothelial cells, mediated by pericyte-produced miR-132 in response to hypoxia and taken up by endothelial cells passing through exosomes [104106].

MiR-132 expression is also regulated by CREB [107, 108], enhances the frequency and amplitude of excitatory potentials in neurons and increases dendritic length and arborization by targeting the brain-enriched GTPase-activating protein p250GAP [109, 110]. MiR-132 triggered marked increases in dendritic spine density, while either underexpression or overexpression of miR-132 caused cognitive impairment in supra-physiological conditions [100, 111]. Similarly, BDNF is regulated by CREB and a negative feedback interaction between the previously described miRNA-1/206 and miRNA-132/212 regulates BDNF expression in the brain [112]. Notably, miRNA-132/212 is also involved in the brain-immune axis and miR-132 mediates an anti-inflammatory effect by targeting acetylcholinesterase, thus increasing acetylcholine that reduces cytokine production [113, 114]. Furthermore, projections from basal forebrain neurons to cortical microvessels (nervi vasorum) and astrocytes containing primarily acetylcholine and nitric oxide synthase (NOS) have contributed to increased cerebral blood flow [77].

5.4. MiR-29

Another miRNA family dysregulated in cerebrovascular disorders and regulated by Ang II is miR-29 [74, 98]. The miR-29 family is linked to cardiac and vascular ageing and counteracts fibrosis by regulating extracellular matrix metallopeptidases [115]. Ang II increased miR-29b in cardiac fibroblasts with no effect in myocytes [116]. In the renal cortex of spontaneously hypertensive rats and in renal tubular epithelial cells, Ang II decreased the expression of miR-29b [117]. Notably, ET-1 decreased miR-29a expression in cardiac myocytes in vitro [118]. MiR-29b is increased in rat brain after focal ischaemia in vivo and in primary neurons exposed to oxygen/glucose deprivation in vitro [119]. Treatment of rats with peroxisome proliferator-activated receptor gamma (PPARγ) agonists protected against ischaemia-reperfusion injury by decreasing miR-29a and miR-29c levels; correspondingly, apoptosis was induced by overexpressing miR-29 [120]. However, mouse models of middle cerebral artery occlusion have inconsistently demonstrated increased and reduced miR-29 levels [119, 121123]. These conflicting findings have a number of possible explanations including animal age and species, as well as techniques and biosamples used, or other factors discussed below.

Despite the inconsistent evidence, a meta-analysis of microRNAs induced by aerobic exercise in humans evaluated left ventricle hypertrophy and proposed miR-29 family to be antihypertrophic and miR-34 family to be prohypertrophic [124]. MiR-34 was increased in patients with cardiovascular disorders in response to stress [125], which promotes apoptosis and cardiac autophagy [102]. By contrast, myocardial hypertrophy induced by Ang II/AT1R activation in rats is antagonized by miR-34 and its inhibition stimulated Ang II signalling via atrial natriuretic peptide [126]. AT1R activation increased intracellular calcium levels producing vasoconstriction in vascular smooth muscle cells. In addition, in endothelial cells, elevation of intracellular calcium levels contributes to the inhibition of nitric oxide production by atrial natriuretic peptide [127].

5.5. MiR-34

MiR-34 is involved in cardiac and endothelial senescence, characterized by decreased production of the vasodilator nitric oxide by endothelial nitric oxide synthase, inflammation and resultant endothelial dysfunction [128]. MiR-34 promotes endothelial senescence by downregulating the histone deacetylase sirtuin-1 [129] and regulates cardiac contractile function during ageing and after acute myocardial infarction, as a result of inducing DNA damage and telomere attrition [130]. Transplantation of bone marrow-derived mononuclear cells from patients with cardiovascular disease induced cell death, while inhibition of the elevated levels of miR-34a ex vivo improved the functional benefit of transplanted bone marrow-derived mononuclear cells in mice after acute myocardial infarction in vivo [131]. Inhibition of miR-34 also attenuated ischaemia-induced cardiac remodelling, atrial enlargement and improved systolic function [125, 132].

By contrast, miR-34 promoted differentiation of mouse embryonic neural stem cells to post-mitotic neurons by targeting sirtuin-1 [133]. Along with miR-132/212, miR-34 was upregulated in human epilepsy screenings and pilocarpine-induced status epilepticus in rats [134139], suggesting neuronal activity-based regulation. MiR-34 expression in the amygdala is also linked to repression of stress-induced anxiety [140], modulates ageing and neurodegeneration in Drosophila [141] and is associated with cognitive impairment [142].

The miRNA families described are functionally relevant in the development of cardiovascular and cerebrovascular disorders, some of which appear to link cerebral ischaemia, endothelial dysfunction and cognitive impairment. Current therapy for cerebral ischaemia is limited to the use of recombinant tissue-plasminogen activator (tPA). Endogenous tPA is primarily expressed in endothelial cells and interactions between tPA and low-density lipoprotein receptor-related protein (LRP) are important for the hippocampal activity-dependent strengthening of synapses known as long-term potentiation (LTP) [143]. AT1R activation causes increased expression of tPA inhibitor (tPA-I), which binds to LRP and blocks its interaction with other ligands, including apolipoprotein E and alpha 2-macroglobulin [144]. Furthermore, tPA-I limits the maturation of proBDNF to BDNF and impedes protein synthesis-dependent late-phase LTP and hippocampal plasticity, mechanisms for learning and memory [145]. Chronic administration of tPA improved cognition in a APPswe/PS1 transgenic mice [146]. MiR-34 has two different binding sites at the 3′UTR of tPA-I, one of which has the highest probability of binding amongst the 108 miRNAs for this transcript. LRP1 is subject to regulation by 22 miRNAs, including miR-125 with one binding site and miR-212 with two binding sites [48].

There has been a recent consensus view on the roles of microRNAs, platelet and endothelial dysfunction in vascular disease and inflammation [147]. MiR-132/212 and miR-29 families target some proteins involved in endothelial dysfunction, such as the actin-related protein 2/3 complex, platelet-derived growth factor and aquaporin 4 [48]; the latter two are particularly relevant in the maintenance of blood-brain barrier (BBB) integrity [148, 149]. Factors involved in BBB disruption include chronic hypertension, ischaemia, trauma, infections and inflammation. Throughout the life course, these factors are likely to cause epigenetic modifications including miRNA fluctuations, leading to reduced protein translation and degradation of mRNA transcripts necessary for BBB integrity. BBB disruption is relevant in understanding the spectrum of clinical manifestations resulting from cerebrovascular disorders.


6. miRNAs challenges and considerations

More than 200 miRNAs have been found to be dysregulated in cerebrovascular disorders, with some inconsistency between studies [7476, 150152]. Inconsistencies likely relate partly to the size of the investigated cohorts, particularly since miRNAs may reflect the presence of comorbidities and hence statistical power and specificity would be lessened. Increasing the number of individuals and adding additional specificity (e.g. identifying disease-specific miRNAs as controls) might enable discrimination between the effects of dysregulated miRNAs. For instance, the ability to differentiate between changes in miRNAs associated with haemorrhagic and ischaemic cerebrovascular disorders and in the presence or absence of amyloid deposition or dementia, would be useful. Equally, changes in miRNA signatures could also explain pathophysiological processes in common, such as endothelial disruption and hypoxia due to hypoperfusion.

A second important factor in interpreting data across studies is that of methods used. miRNA detection with high sensitivity and specificity is demanding. The target sequence is present in the primary transcript, the precursor and the mature miRNA; some miRNAs within the same family differ by just a single nucleotide [153, 154]. Profiling can be achieved via three major methods: amplification using quantitative real-time polymerase chain reaction (qRT-PCR), hybridization based on microarrays and sequencing by next-generation sequencing (NGS) technologies [153, 155]. Due to the small size of miRNAs, guanidine-cytosine (GC) content and similar target sequence, hybridization-based methods lack specificity. NGS technologies have provided a considerable aid to advance the field of miRNA, elucidating new miRNAs and applying new criteria for the RNA sequences to be recognized as miRNAs. Studies evaluating sensitivity, specificity, quantification accuracy and reproducibility of different assays have shown that miRNA levels were dependent on the nature of the technique and also with differences between commercial kits [154, 156, 157]. Despite the advantages of NGS, a validation method is highly recommended for those dysregulated miRNAs in large-scale screenings. Although there is no specific consensus paper, qRT-PCR has been widely cited as the gold standard in miRNA research, providing specificity between isomiRs and using stem-loop primers for discrimination from primary miRNAs, pre-miRNAs and degraded mRNA [153, 158].

Another factor is the handling and sample source of miRNAs that are cell type specific and thus, the proportion of different cells contained in a sample can vary. In addition, blood contains high levels of RNase activity; while miRNAs are protected from RNase under normal conditions, their extraction causes immediate degradation if extracted and spiked back to plasma [153]. Other pre-analytic variables might also affect its profiling, such as centrifugation [159]. Collection and handling procedures are relevant to reliably detect dysregulated miRNAs. Exosomal RNA is protected by RNase A treatment and exosomes provide a consistent source of miRNA for disease biomarker detection [160]. Sources like formalin-fixed tissue have been found to be highly reliable [79, 153].

In studies of disease, the pathological stage of the disease, post-mortem status and the agonal state prior to death should also be considered as miRNAs measured could represent causal and/or responsive mechanisms. Thus, there is a need to discriminate between miRNAs produced under normal conditions in different cell types for effective comparisons with those regulated by an environmental insult (e.g. hypoxia), those regulated by the activation of a receptor (e.g. AT1R) or by a common downstream regulator (e.g. CREB). Indeed, during the natural history of a disease, microRNAs will likely fluctuate and their final signature might represent a retrospective picture of various protective mechanisms and aberrant dysregulations.

Finally, the effects of miRNAs on their targets should be viewed in the context of a whole functional analysis [161]. For instance, renin-sensitive microRNAs correlate with atherosclerosis plaque progression [162]. It is conceivable that only a specific combination of microRNAs produces a relevant physiological response. Several outcomes in miRNA research appear to be the result of well-defined miRNA-target-related effects. Nevertheless, the impact of a single miRNA via a specific target is related to the total number of different transcripts it targets and also by the number of other miRNAs that share the same target. It is reasonable to attribute a functional characteristic to a miRNA, based on the experimental outcome, such as in luciferase assays. However, luciferase assays are not able to differentiate between canonical and non-canonical binding sites, neither if the effects are a result of direct miRNA binding to the transcript or by modifying transcription factors.

Furthermore, the experimental outcome will depend on the mRNAs expressed in that cell at that time. For instance, 213 miRNAs can bind at the 3′UTR of the anti-apoptotic protein BCL-2, whereby one could assume that those 213 miRNAs are pro-apoptotic by downregulating BCL-2. However, one of those 213 miRNAs alone could have several hundred targets, some of which promote apoptosis and others favouring survival. Thus, examination of the complete array of targets is needed to provide a functional analysis including an assessment of overlapping targets between miRNAs [161, 163]. Another consideration is the probability rate by which a miRNA binds to the 3′ UTR. Agarwal et al. developed a score based on 14 features (total context score) to allow determination of the probability of miRNA binding and categorization of miRNAs into percentiles based on the total context score [48]. Finally, it is prudent to consider the number of copies of a miRNA expressed. Some miRNAs, such as miR-124 and miR-128, are highly expressed up to 30,000–50,000 copies per neuron, while others can be as low as 1–2 copies per neuron [29]. Therefore, the biological impact of miRNAs relies on the combinatorial signature, the number of miRNA copies expressed, their affinity for different transcripts and the existing mRNA environment accessible for remodelling.


7. Conclusions

In summary, miRNAs are essential for cell fate and differentiation and their effects depend on the mRNA environment expressed, which can be transient over time and subject to dysregulation that may lead to disease. As a highly dynamic and interactive process, epigenetics and particularly miRNAs play a significant role in cognition [164, 165]. Drosha and Dicer are expressed throughout the brain with a higher expression in the hippocampus and dentate gyrus [166]. Functional analysis through bioinformatics and the use of next-generation sequencing could reveal a miRNA signature that helps to explain the effects on pathways and the fluctuations seen over the development of a specific disease. This could allow identification of a small group of miRNAs that are determinant in the clinical manifestation and therefore potential targets for diagnosis and therapeutic intervention. These would have a great advantage as therapies due to their small size and lipidic transport across the BBB, direct intracellular interaction with the transcriptome and may be able to facilitate regeneration while obviating the consequence of a degenerative microenvironment.


  1. 1. Romaine SP, Charchar FJ, Samani NJ, Tomaszewski M. Circulating microRNAs and hypertension-from new insights into blood pressure regulation to biomarkers of cardiovascular risk. Curr Opin Pharmacol. 2016;27:1-7. doi:10.1016/j.coph.2015.12.002
  2. 2. Marques FZ, Booth SA, Charchar FJ. The emerging role of non-coding RNA in essential hypertension and blood pressure regulation. J Hum Hypertens. 2015;29(8):459-67. doi:10.1038/jhh.2014.99
  3. 3. Re RN. Mechanisms of disease: local renin–angiotensin–aldosterone systems and the pathogenesis and treatment of cardiovascular disease. Nat Rev Cardiol. 2004;1(1):42-7. doi:10.1038/ncpcardio0012
  4. 4. Turgut F, Balogun RA, Abdel-Rahman EM. Renin-angiotensin-aldosterone system blockade effects on the kidney in the elderly: benefits and limitations. Clin J Am Soc Nephrol: CJASN. 2010;5(7):1330-9. doi:10.2215/cjn.08611209
  5. 5. Sibley S. Hypertension, obesity and the renin-angiotensin system: a tale of tight associations. Minnesota Medicine. 2003;86(1):46-8. Retrieved from [Accessed 2016-07-10].
  6. 6. Batkai S, Thum T. MicroRNAs in hypertension: mechanisms and therapeutic targets. Curr Hypertens Rep. 2012;14(1):79-87. doi:10.1007/s11906-011-0235-6
  7. 7. Friso S, Carvajal CA, Fardella CE, Olivieri O. Epigenetics and arterial hypertension: the challenge of emerging evidence. Transl Res. 2015;165(1):154-65. doi:10.1016/j.trsl.2014.06.007
  8. 8. Munroe PB, Barnes MR, Caulfield MJ. Advances in blood pressure genomics. Circ Res. 2013;112(10):1365-79. doi:10.1161/CIRCRESAHA.112.300387
  9. 9. Nazari-Jahantigh M, Wei Y, Schober A. The role of microRNAs in arterial remodelling. Thromb Haemost. 2012;107(4):611-8. doi:10.1160/TH11-12-0826
  10. 10. Zhong X, Liao Y, Chen L, Liu G, Feng Y, Zeng T, et al. The MicroRNAs in the pathogenesis of metabolic memory. Endocrinology. 2015;156(9):3157-68. doi:10.1210/en.2015-1063
  11. 11. Bartel DP. microRNAs genomics, biogenesis, mechanism and function. Cell. 2004;116:281-97. doi:10.1016/S0092-8674(04)00045-5
  12. 12. Bartel DP. MicroRNAs: target recognition and regulatory functions. Cell. 2009;136(2):215-33. doi:10.1016/j.cell.2009.01.002
  13. 13. Miyoshi K, Miyoshi T, Siomi H. Many ways to generate microRNA-like small RNAs: non-canonical pathways for microRNA production. Mol Genet Genomics. 2010;284(2):95-103. doi:10.1007/s00438-010-0556-1
  14. 14. Winter J, Jung S, Keller S, Gregory RI, Diederichs S. Many roads to maturity microRNA biogenesis pathways and their regulation. Nat Cell Biol. 2009;11(3):228-34. doi:10.1038/ncb0309-228
  15. 15. Kozomara A, Griffiths-Jones S. miRBase: annotating high confidence microRNAs using deep sequencing data. Nucleic Acids Res. 2014;42:D68-73. doi:10.1093/nar/gkt1181
  16. 16. Zhou X, Yang P-C. MicroRNA: a small molecule with a big biological impact. MicroRNA. 2012;1(1):1. doi:10.2174/2211536611201010001
  17. 17. Basak I, Patil KS, Alves G, Larsen JP, Moller SG. microRNAs as neuroregulators, biomarkers and therapeutic agents in neurodegenerative diseases. Cell Mol Life Sci. 2016;73(4):811-27. doi:10.1007/s00018-015-2093-x
  18. 18. Pelechano V, Steinmetz LM. Gene regulation by antisense transcription. Nat Rev Genet. 2013;14(12):880-93. doi:10.1038/nrg3594
  19. 19. Romero CA, Orias M, Weir MR. Novel RAAS agonists and antagonists: clinical applications and controversies. Nat Rev Endocrinol. 2015;11(4):242-52. doi:10.1038/nrendo.2015.6
  20. 20. Wright JW, Kawas LH, Harding JW. The development of small molecule angiotensin IV analogs to treat Alzheimer’s and Parkinson’s diseases. Prog Neurobiol. 2015;125:26-46. doi:10.1016/j.pneurobio.2014.11.004
  21. 21. Savaskan E. The role of the brain renin-angiotensin system in neurodegenerative disorders. Curr Alzheimer Res. 2005;2(1):29-35. doi:10.2174/1567205052772740
  22. 22. Wright JW, Harding JW. Brain renin-angiotensin—a new look at an old system. Prog Neurobiol. 2011;95(1):49-67. doi:10.1016/j.pneurobio.2011.07.001
  23. 23. Wright JW. Introduction: aminopeptidases and hypertension-mechanisms of action and therapeutic strategies. Heart Fail Rev. 2008;13(3):271-2. doi:10.1007/s10741-007-9076-4
  24. 24. Wright JW, Kawas LH, Harding JW. A role for the brain RAS in Alzheimer’s and Parkinson’s diseases. Front Endocrinol. 2013;4:158. doi:10.3389/fendo.2013.00158
  25. 25. Lautner RQ, Villela DC, Fraga-Silva RA, Silva N, Verano-Braga T, Costa-Fraga F, et al. Discovery and characterization of alamandine: a novel component of the renin-angiotensin system. Circ Res. 2013;112(8):1104-11. doi:10.1161/circresaha.113.301077
  26. 26. Villela DC, Passos-Silva DG, Santos RA. Alamandine: a new member of the angiotensin family. Curr Opin Nephrol Hypertens. 2014;23(2):130-4. doi:10.1097/01.mnh.0000441052.44406.92
  27. 27. Etelvino GM, Peluso AA, Santos RA. New components of the renin-angiotensin system: alamandine and the MAS-related G protein-coupled receptor D. Curr Hypertens Rep. 2014;16(6):433. doi:10.1007/s11906-014-0433-0
  28. 28. Mohr AM, Mott JL. Overview of microRNA biology. Semin Liver Dis. 2015;35(1):3-11. doi:10.1055/s-0034-1397344
  29. 29. O’Carroll D, Schaefer A. General principals of miRNA biogenesis and regulation in the brain. Neuropsychopharmacology. 2013;38(1):39-54. doi:10.1038/npp.2012.87
  30. 30. Baskerville S, Bartel DP. Microarray profiling of microRNAs reveals frequent coexpression with neighboring miRNAs and host genes. RNA. 2005;11(3):241-7. doi:10.1261/rna.7240905
  31. 31. Meunier J, Lemoine F, Soumillon M, Liechti A, Weier M, Guschanski K, et al. Birth and expression evolution of mammalian microRNA genes. Genome Res. 2013;23(1):34-45. doi:10.1101/gr.140269.112
  32. 32. Berezikov E. Evolution of microRNA diversity and regulation in animals. Nat Rev Genet. 2011;12(12):846-60. doi:10.1038/nrg3079
  33. 33. Guerra-Assunção JA, Enright AJ. Large-scale analysis of microRNA evolution. BMC Genomics. 2012;13(1):1. doi:10.1186/1471-2164-13-218
  34. 34. Gregory RI, Yan KP, Amuthan G, Chendrimada T, Doratotaj B, Cooch N, et al. The microprocessor complex mediates the genesis of microRNAs. Nature. 2004;432(7014):235-40. doi:10.1038/nature03120
  35. 35. Grimson A, Srivastava M, Fahey B, Woodcroft BJ, Chiang HR, King N, et al. Early origins and evolution of microRNAs and Piwi-interacting RNAs in animals. Nature. 2008;455(7217):1193-7. doi:10.1038/nature07415
  36. 36. Ameres SL, Zamore PD. Diversifying microRNA sequence and function. Nat Rev Mol Cell Biol. 2013;14(8):475-88. doi:10.1038/nrm3611
  37. 37. Czech B, Hannon GJ. Small RNA sorting: matchmaking for Argonautes. Nat Rev Genet. 2011;12(1):19-31. doi:10.1038/nrg2916
  38. 38. Yoon JH, Abdelmohsen K, Gorospe M. Functional interactions among microRNAs and long noncoding RNAs. Semin Cell Dev Biol. 2014;34:9-14. doi:10.1016/j.semcdb.2014.05.015
  39. 39. Kai ZS, Pasquinelli AE. MicroRNA assassins: factors that regulate the disappearance of miRNAs. Nat Struct Mol Biol. 2010;17(1):5-10. doi:10.1038/nsmb.1762
  40. 40. Diederichs S, Haber DA. Dual role for argonautes in microRNA processing and posttranscriptional regulation of microRNA expression. Cell. 2007;131:1097-108. doi:10.1016/j.cell.2007.10.032
  41. 41. Salmanidis M, Pillman K, Goodall G, Bracken C. Direct transcriptional regulation by nuclear microRNAs. Int J Biochem Cell Biol. 2014;54:304-11. doi:10.1016/j.biocel.2014.03.010
  42. 42. Liu J, Valencia-Sanchez MA, Hannon GJ, Parker R. MicroRNA-dependent localization of targeted mRNAs to mammalian P-bodies. Nat Cell Biol. 2005;7(7):719-23. doi:10.1038/ncb1274
  43. 43. Braun JE, Huntzinger E, Fauser M, Izaurralde E. GW182 proteins directly recruit cytoplasmic deadenylase complexes to miRNA targets. Mol Cell. 2011;44(1):120-33. doi:10.1016/j.molcel.2011.09.007
  44. 44. Chekulaeva M, Mathys H, Zipprich JT, Attig J, Colic M, Parker R, et al. miRNA repression involves GW182-mediated recruitment of CCR4-NOT through conserved W-containing motifs. Nat Struct Mol Biol. 2011;18(11):1218-26. doi:10.1038/nsmb.2166
  45. 45. Fabian MR, Cieplak MK, Frank F, Morita M, Green J, Srikumar T, et al. miRNA-mediated deadenylation is orchestrated by GW182 through two conserved motifs that interact with CCR4-NOT. Nat Struct Mol Biol. 2011;18(11):1211-7. doi:10.1038/nsmb.2149
  46. 46. Friedman RC, Farh KK, Burge CB, Bartel DP. Most mammalian mRNAs are conserved targets of microRNAs. Genome Res. 2009;19(1):92-105. doi:10.1101/gr.082701.108
  47. 47. Shin C, Nam JW, Farh KK, Chiang HR, Shkumatava A, Bartel DP. Expanding the microRNA targeting code: functional sites with centered pairing. Mol Cell. 2010;38(6):789-802. doi:10.1016/j.molcel.2010.06.005
  48. 48. Agarwal V, Bell GW, Nam JW, Bartel DP. Predicting effective microRNA target sites in mammalian mRNAs. 2015;4:e05005. doi:10.7554/eLife.05005
  49. 49. Belting M, Wittrup A. Nanotubes, exosomes and nucleic acid-binding peptides provide novel mechanisms of intercellular communication in eukaryotic cells: implications in health and disease. J Cell Biol. 2008;183(7):1187-91. doi:10.1083/jcb.200810038
  50. 50. Paschon V, Takada SH, Ikebara JM, Sousa E, Raeisossadati R, Ulrich H, et al. Interplay between exosomes, microRNAs and toll-like receptors in brain disorders. Mol Neurobiol. 2016;53(3):2016-28. doi:10.1007/s12035-015-9142-1
  51. 51. Chen X, Liang H, Zhang J, Zen K, Zhang CY. Horizontal transfer of microRNAs: molecular mechanisms and clinical applications. Protein Cell. 2012;3(1):28-37. doi:10.1007/s13238-012-2003-z
  52. 52. Valadi H, Ekstrom K, Bossios A, Sjostrand M, Lee JJ, Lotvall JO. Exosome-mediated transfer of mRNAs and microRNAs is a novel mechanism of genetic exchange between cells. Nat Cell Biol. 2007;9(6):654-9. doi:10.1038/ncb1596
  53. 53. Wahlgren J, De LKT, Brisslert M, Vaziri Sani F, Telemo E, Sunnerhagen P, et al. Plasma exosomes can deliver exogenous short interfering RNA to monocytes and lymphocytes. Nucleic Acids Res. 2012;40(17):e130. doi:10.1093/nar/gks463
  54. 54. Vlassov AV, Magdaleno S, Setterquist R, Conrad R. Exosomes: current knowledge of their composition, biological functions and diagnostic and therapeutic potentials. Biochim Biophys Acta. 2012;1820(7):940-8. doi:10.1016/j.bbagen.2012.03.017
  55. 55. Zhang J, Li S, Li L, Li M, Guo C, Yao J, et al. Exosome and exosomal microRNA: trafficking, sorting and function. Genom Proteom Bioinform. 2015;13(1):17-24. doi:10.1016/j.gpb.2015.02.001
  56. 56. Janas T, Janas MM, Sapon K, Janas T. Mechanisms of RNA loading into exosomes. FEBS Lett. 2015;589(13):1391-8. doi:10.1016/j.febslet.2015.04.036
  57. 57. Das S, Halushka MK. Extracellular vesicle microRNA transfer in cardiovascular disease. Cardiovasc Pathol. 2015;24(4):199-206. doi:10.1016/j.carpath.2015.04.007
  58. 58. Sahoo S, Losordo DW. Exosomes and cardiac repair after myocardial infarction. Circ Res. 2014;114(2):333-44. doi:10.1161/CIRCRESAHA.114.300639
  59. 59. Hergenreider E, Heydt S, Treguer K, Boettger T, Horrevoets AJ, Zeiher AM, et al. Atheroprotective communication between endothelial cells and smooth muscle cells through miRNAs. Nat Cell Biol. 2012;14(3):249-56. doi:10.1038/ncb2441
  60. 60. Kuwabara Y, Ono K, Horie T, Nishi H, Nagao K, Kinoshita M, et al. Increased microRNA-1 and microRNA-133a levels in serum of patients with cardiovascular disease indicate myocardial damage. Circ Cardiovasc Genet. 2011;4(4):446-54. doi:10.1161/circgenetics.110.958975
  61. 61. Xin H, Li Y, Buller B, Katakowski M, Zhang Y, Wang X, et al. Exosome-mediated transfer of miR-133b from multipotent mesenchymal stromal cells to neural cells contributes to neurite outgrowth. Stem Cells (Dayton, Ohio). 2012;30(7):1556-64. doi:10.1002/stem.1129
  62. 62. Xin H, Li Y, Liu Z, Wang X, Shang X, Cui Y, et al. MiR-133b promotes neural plasticity and functional recovery after treatment of stroke with multipotent mesenchymal stromal cells in rats via transfer of exosome-enriched extracellular particles. Stem Cells. 2013;31(12):2737-46. doi:10.1002/stem.1409
  63. 63. Wang F, Long G, Zhao C, Li H, Chaugai S, Wang Y, et al. Plasma microRNA-133a is a new marker for both acute myocardial infarction and underlying coronary artery stenosis. J Transl Med. 2013;11:222. doi:10.1186/1479-5876-11-222
  64. 64. Hess DC, Blauenfeldt RA Andersen G, Hougaard KD, Hoda MN, Ding Y, et al. Remote ischaemic conditioning—a new paradigm of self-protection in the brain. Nat Rev Neurol. 2015;11:698-710. doi:10.1038/nrneurol.2015.223
  65. 65. Hausenloy DJ, Candilio L, Evans R, Ariti C, Jenkins DP, Kolvekar S, et al. Remote ischemic preconditioning and outcomes of cardiac surgery. N Engl J Med. 2015;373:1408-17. doi:10.1056/NEJMoa1413534
  66. 66. Hausenloy DJ, Yellon DM. The therapeutic potential of ischemic conditioning: an update. Nat Rev Cardiol. 2011;8(11):619-29. doi:10.1038/nrcardio.2011.85
  67. 67. Li J, Rohailla S, Gelber N, Rutka J, Sabah N, Gladstone RA, et al. MicroRNA-144 is a circulating effector of remote ischemic preconditioning. Basic Res Cardiol. 2014;109(5):423. doi:10.1007/s00395-014-0423-z
  68. 68. Hu Q, Luo W, Huang L, Huang R, Chen R. Apoptosis-related microRNA changes in the right atrium induced by remote ischemic perconditioning during valve replacement surgery. Sci Rep. 2015;6:18959. doi:10.1038/srep18959
  69. 69. Brandenburger T, Grievink H, Heinen N, Barthel F, Huhn R, Stachuletz F, et al. Effects of remote ischemic preconditioning and myocardial ischemia on microRNA-1 expression in the rat heart in vivo. Shock. 2014;42(3):234-8. doi:10.1097/shk.0000000000000201
  70. 70. Kinet V, Halkein J, Dirkx E, Windt LJ. Cardiovascular extracellular microRNAs: emerging diagnostic markers and mechanisms of cell-to-cell RNA communication. Front Genet. 2013;4:214. doi:10.3389/fgene.2013.00214
  71. 71. Fang L, Ellims AH, Moore XL, White DA, Taylor AJ, Chin-Dusting J, et al. Circulating microRNAs as biomarkers for diffuse myocardial fibrosis in patients with hypertrophic cardiomyopathy. J Transl Med. 2015;13:314. doi:10.1186/s12967-015-0672-0
  72. 72. Grasso M, Piscopo P, Confaloni A, Denti MA. Circulating miRNAs as biomarkers for neurodegenerative disorders. Molecules. 2014;19(5):6891-910. doi:10.3390/molecules19056891
  73. 73. Guay C, Regazzi R. Circulating microRNAs as novel biomarkers for diabetes mellitus. Nat Rev Endocrinol. 2013;9(9):513-21. doi:10.1038/nrendo.2013.86
  74. 74. Li M, Zhang J. Circulating microRNAs: potential and emerging biomarkers for diagnosis of cardiovascular and cerebrovascular diseases. Biomed Res Int. 2015;2015:730535. doi:10.1155/2015/730535
  75. 75. Li WY, Jin J, Chen J, Guo Y, Tang J, Tan S. Circulating microRNAs as potential non-invasive biomarkers for the early detection of hypertension-related stroke. J Hum Hypertens. 2014;28(5):288-91. doi:10.1038/jhh.2013.94
  76. 76. Wang W, Sun G, Zhang L, Shi L, Zeng Y. Circulating microRNAs as novel potential biomarkers for early diagnosis of acute stroke in humans. J Stroke Cerebrovasc Dis. 2014;23(10):2607-13. doi:10.1016/j.jstrokecerebrovasdis.2014.06.002
  77. 77. Cipolla MJ. The cerebral circulation. In: Control of Cerebral Blood Flow, Chapter 5. San Rafael (CA): Morgan & Claypool Life Sciences; 2009.
  78. 78. Mooren FC, Viereck J, Kruger K, Thum T. Circulating microRNAs as potential biomarkers of aerobic exercise capacity. Am J Physiol Heart Circ Physiol. 2014;306(4):H557-63. doi:10.1152/ajpheart.00711.2013
  79. 79. Kakimoto Y, Kamiguchi H, Ochiai E, Satoh F, Osawa M. MicroRNA stability in postmortem FFPE tissues: quantitative analysis using autoptic samples from acute myocardial infarction patients. PLoS One. 2015;10(6):e0129338. doi:10.1371/journal.pone.0129338
  80. 80. Zhang R, Niu H, Ban T, Xu L, Li Y, Wang N, et al. Elevated plasma microRNA-1 predicts heart failure after acute myocardial infarction. Int J Cardiol. 2013;166(1):259-60. doi:10.1016/j.ijcard.2012.09.108
  81. 81. Chen J, Yin H, Jiang Y, Radhakrishnan SK, Huang ZP, Li J, et al. Induction of microRNA-1 by myocardin in smooth muscle cells inhibits cell proliferation. Arterioscler Thromb Vasc Biol. 2011;31(2):368-75. doi:10.1161/atvbaha.110.218149
  82. 82. Jiang Y, Yin H, Zheng XL. MicroRNA-1 inhibits myocardin-induced contractility of human vascular smooth muscle cells. J Cell Physiol. 2010;225(2):506-11. doi:10.1002/jcp.22230
  83. 83. Liu K, Ying Z, Qi X, Shi Y, Tang Q. MicroRNA-1 regulates the proliferation of vascular smooth muscle cells by targeting insulin-like growth factor 1. Int J Mol Med. 2015;36(3):817-24. doi:10.3892/ijmm.2015.2277
  84. 84. van Mil A, Vrijsen KR, Goumans MJ, Metz CH, Doevendans PA, Sluijter JP. MicroRNA-1 enhances the angiogenic differentiation of human cardiomyocyte progenitor cells. J Mol Med. 2013;91(8):1001-12. doi:10.1007/s00109-013-1017-1
  85. 85. Ma JC, Duan MJ, Sun LL, Yan ML, Liu T, Wang Q, et al. Cardiac over-expression of microRNA-1 induces impairment of cognition in mice. Neuroscience. 2015;299:66-78. doi:10.1016/j.neuroscience.2015.04.061
  86. 86. Cheng C, Wang Q, You W, Chen M, Xia J. MiRNAs as biomarkers of myocardial infarction: a meta-analysis. PLoS One. 2014;9(2):e88566. doi:10.1371/journal.pone.0088566
  87. 87. Li C, Pei F, Zhu X, Duan DD, Zeng C. Circulating microRNAs as novel and sensitive biomarkers of acute myocardial Infarction. Clin Biochem. 2012;45(10-11):727-32. doi:10.1016/j.clinbiochem.2012.04.013
  88. 88. Simonson B, Das S. MicroRNA therapeutics: the next magic bullet? Mini Rev Med Chem. 2015;15(6):467-74. doi:10.2174/1389557515666150324123208
  89. 89. Li XJ, Ren ZJ, Tang JH. MicroRNA-34a: a potential therapeutic target in human cancer. Cell Death Dis. 2014;5(7). doi:10.1038/cddis.2014.270
  90. 90. Misso G, Martino MTD, Rosa GD, Farooqi AA, Lombardi A, Campani V, et al. Mir-34: a new weapon against cancer? Mol Ther Nucleic Acids. 2014;3(9):e194. doi:10.1038/mtna.2014.47
  91. 91. Zhang MY, Li SH, Huang GL, Lin GH, Shuang ZY, Lao XM, et al. Identification of a novel microRNA signature associated with intrahepatic cholangiocarcinoma (ICC) patient prognosis. BMC Cancer. 2015;15:64. doi:10.1186/s12885-015-1067-6
  92. 92. Zhao W, Zhao SP, Zhao YH. MicroRNA-143/-145 in cardiovascular diseases. Biomed Res Int. 2015;2015:531740. doi:10.1155/2015/531740
  93. 93. Cordes KR, Sheehy NT, White MP, Berry EC, Morton SU, Muth AN, et al. miR-145 and miR-143 regulate smooth muscle cell fate and plasticity. Nature. 2009;460(7256):705-10. doi:10.1038/nature08195
  94. 94. Miyasaka KY, Kida YS, Banjo T, Ueki Y, Nagayama K, Matsumoto T, et al. Heartbeat regulates cardiogenesis by suppressing retinoic acid signaling via expression of miR-143. Mech Dev. 2011;128(1-2):18-28. doi:10.1016/j.mod.2010.09.002
  95. 95. Elia L, Quintavalle M, Zhang J, Contu R, Cossu L, Latronico MVG, et al. The knockout of miR-143 and -145 alters smooth muscle cell maintenance and vascular homeostasis in mice: correlates with human disease. Cell Death Differ. 2009;16(12):1590-8. doi:10.1038/cdd.2009.153
  96. 96. Kontaraki JE, Marketou ME, Zacharis EA, Parthenakis FI, Vardas PE. Differential expression of vascular smooth muscle-modulating microRNAs in human peripheral blood mononuclear cells: novel targets in essential hypertension. J Hum Hypertens 2013;28(8):510-6. doi:10.1038/jhh.2013.117
  97. 97. Eskildsen TV, Jeppesen PL, Schneider M, Nossent AY, Sandberg MB, Hansen PB, et al. Angiotensin II regulates microRNA-132/-212 in hypertensive rats and humans. Int J Mol Sci. 2013;14(6):11190-207. doi:10.3390/ijms140611190
  98. 98. Obama T, Eguchi S. MicroRNA as a novel component of the tissue renin angiotensin system. J Mol Cell Cardiol. 2014;75:98-9. doi:10.1016/j.yjmcc.2014.07.004
  99. 99. Eskildsen TV, Schneider M, Sandberg MB, Skov V, Bronnum H, Thomassen M, et al. The microRNA-132/212 family fine-tunes multiple targets in Angiotensin II signalling in cardiac fibroblasts. J Renin Angiotensin Aldosterone Syst. 2015;16(4):1288-97. doi:10.1177/1470320314539367
  100. 100. Hansen KF, Karelina K, Sakamoto K, Wayman GA, Impey S, Obrietan K. miRNA-132: a dynamic regulator of cognitive capacity. Brain Struct Funct. 2013;218(3):817-31. doi:10.1007/s00429-012-0431-4
  101. 101. Kumarswamy R, Volkmann I, Beermann J, Napp LC, Jabs O, Bhayadia R, et al. Vascular importance of the miR-212/132 cluster. Eur Heart J. 2014;35(45):3224-31. doi:10.1093/eurheartj/ehu344
  102. 102. Pacurari M, Tchounwou PB. Role of microRNAs in renin-angiotensin-aldosterone system-mediated cardiovascular inflammation and remodeling. Int J Inflam. 2015;2015:101527. doi:10.1155/2015/101527
  103. 103. Wanet A, Tacheny A, Arnould T, Renard P. miR-212/132 expression and functions: within and beyond the neuronal compartment. Nucleic Acids Res. 2012;40(11):4742-53. doi:10.1093/nar/gks151
  104. 104. Emanueli C, Shearn AI, Angelini GD, Sahoo S. Exosomes and exosomal miRNAs in cardiovascular protection and repair. Vascul Pharmacol. 2015;71:24-30. doi:10.1016/j.vph.2015.02.008
  105. 105. Campagnolo P, Cesselli D, Zen AAH, Beltrami AP, Kränkel N, Katare R, et al. Human adult vena saphena contains perivascular progenitor cells endowed with clonogenic and proangiogenic potential. Circulation. 2010;121:1735-45. doi:10.1161/CIRCULATIONAHA.109.899252
  106. 106. Katare R, Riu F, Mitchell K, Gubernator M, Campagnolo P, Cui Y, et al. Transplantation of human pericyte progenitor cells improves the repair of infarcted heart through activation of an angiogenic program involving micro-RNA-132. Circ Res. 2011;109:894-906. doi:10.1161/CIRCRESAHA.111.251546
  107. 107. Remenyi J, Hunter CJ, Cole C, Ando H, Impey S, Monk CE, et al. Regulation of the miR-212/132 locus by MSK1 and CREB in response to neurotrophins. Biochem J. 2010;428(2):281-91. doi:10.1042/BJ20100024
  108. 108. Nudelman AS, DiRocco DP, Lambert TJ, Garelick MG, Le J, Nathanson NM, et al. Neuronal activity rapidly induces transcription of the CREB-regulated microRNA-132, in vivo. Hippocampus. 2010;20(4):492-8. doi:10.1002/hipo.20646
  109. 109. Edbauer D, Neilson JR, Foster KA, Wang CF, Seeburg DP, Batterton MN, et al. Regulation of synaptic structure and function by FMRP-associated microRNAs miR-125b and miR-132. Neuron. 2010;65(3):373-84. doi:10.1016/j.neuron.2010.01.005
  110. 110. Wayman GA, Davare M, Ando H, Fortin D, Varlamova O, Cheng HY, et al. An activity-regulated microRNA controls dendritic plasticity by down-regulating p250GAP. Proc Natl Acad Sci U S A. 2008;105(26):9093-8. doi:10.1073/pnas.0803072105
  111. 111. Hansen KF, Sakamoto K, Wayman GA, Impey S, Obrietan K. Transgenic miR132 alters neuronal spine density and impairs novel object recognition memory. PLoS One. 2010;5(11):e15497. doi:10.1371/journal.pone.0015497
  112. 112. Keifer J, Zheng Z, Ambigapathy G. A microRNA-BDNF negative feedback signaling loop in brain: implications for Alzheimer’s Disease. MicroRNA. 2015;4:101-8. doi:10.2174/2211536604666150813152620
  113. 113. O’Neill LA. Boosting the brain’s ability to block inflammation via microRNA-132. Immunity. 2009;31(6):854-5. doi:10.1016/j.immuni.2009.11.004
  114. 114. Shaked I, Meerson A, Wolf Y, Avni R, Greenberg D, Gilboa-Geffen A, et al. MicroRNA-132 potentiates cholinergic anti-inflammatory signaling by targeting acetylcholinesterase. Immunity. 2009;31(6):965-73. doi:10.1016/j.immuni.2009.09.019
  115. 115. Seeger T, Boon RA. MicroRNAs in cardiovascular ageing. J Physiol. 2016;594(8):2085-94. doi:10.1113/JP270557
  116. 116. Jeppesen PL, Christensen GL, Schneider M, Nossent AY, Jensen HB, Andersen DC, et al. Angiotensin II type 1 receptor signalling regulates microRNA differentially in cardiac fibroblasts and myocytes. Br J Pharmacol. 2011;164(2):394-404. doi:10.1111/j.1476-5381.2011.01375.x
  117. 117. Pan J, Zhang J, Zhang X, Zhou X, Lu S, Huang X, et al. Role of microRNA-29b in angiotensin II-induced epithelial-mesenchymal transition in renal tubular epithelial cells. Int J Mol Med. 2014;34(5):1381-7. doi:10.3892/ijmm.2014.1935
  118. 118. Li M, Wang N, Zhang J, He HP, Gong HQ, Zhang R, et al. MicroRNA-29a-3p attenuates ET-1-induced hypertrophic responses in H9c2 cardiomyocytes. Gene. 2016;585(1):44-50. doi:10.1016/j.gene.2016.03.015
  119. 119. Shi G, Liu Y, Liu T, Yan W, Liu X, Wang Y, et al. Upregulated miR-29b promotes neuronal cell death by inhibiting Bcl2L2 after ischemic brain injury. Exp Brain Res. 2012;216(2):225-30. doi:10.1007/s00221-011-2925-3
  120. 120. Ye Y, Hu Z, Lin Y, Zhang C, Perez-Polo JR. Downregulation of microRNA-29 by antisense inhibitors and a PPAR-gamma agonist protects against myocardial ischaemia-reperfusion injury. Cardiovasc Res. 2010;87(3):535-44. doi:10.1093/cvr/cvq053
  121. 121. Pandi G, Nakka VP, Dharap A, Roopra A, Vemuganti R. MicroRNA miR-29c down-regulation leading to de-repression of its target DNA methyltransferase 3a promotes ischemic brain damage. PLoS One. 2013;8(3):e58039. doi:10.1371/journal.pone.0058039
  122. 122. Kole AJ, Swahari V, Hammond SM, Deshmukh M. miR-29b is activated during neuronal maturation and targets BH3-only genes to restrict apoptosis. Genes Dev. 2011;25(2):125-30. doi:10.1101/gad.1975411
  123. 123. Huang LG, Li JP, Pang XM, Chen CY, Xiang HY, Feng LB, et al. MicroRNA-29c Correlates with Neuroprotection Induced by FNS by Targeting Both Birc2 and Bak1 in Rat Brain after Stroke. CNS Neurosci Ther. 2015;21(6):496-503. doi:10.1111/cns.12383
  124. 124. Fernandes T, Barauna VG, Negrao CE, Phillips MI, Oliveira EM. Aerobic exercise training promotes physiological cardiac remodelling involving a set of microRNAs. Am J Physiol Heart Circ Physiol. 2015;309(4):H543-52. doi:10.1152/ajpheart.00899.2014
  125. 125. Harrison C. Cardiovascular disease: Inhibiting microRNA-34 benefits heart disease. Nat Rev Drug Discov. 2012;11(12):908. doi:10.1038/nrd3903
  126. 126. Huang J, Sun W, Huang H, Ye J, Pan W, Zhong Y, et al. miR-34a modulates angiotensin II-induced myocardial hypertrophy by direct inhibition of ATG9A expression and autophagic activity. PLoS One. 2014;9(4):e94382. doi:10.1371/journal.pone.0094382
  127. 127. Kiemer AK, Vollmar AM. Elevation of intracellular calcium levels contributes to the inhibition of nitric oxide production by atrial natriuretic peptide. Immunol Cell Biol. 2001;79(1):11-7. doi:10.1046/j.1440-1711.2001.00969.x
  128. 128. Arunachalam G, Upadhyay R, Ding H, Triggle CR. MicroRNA signature and cardiovascular dysfunction. J Cardiovasc Pharmacol. 2015;65:419-29. doi:10.1097/FJC.0000000000000178
  129. 129. Ito T, Yagi S, Yamakuchi M. MicroRNA-34a regulation of endothelial senescence. Biochem Biophys Res Commun. 2010;398(4):735-40. doi:10.1016/j.bbrc.2010.07.012
  130. 130. Boon RA, Iekushi K, Lechner S, Seeger T, Fischer A, Heydt S, et al. MicroRNA-34a regulates cardiac ageing and function. Nature. 2013;495(7439):107-10. doi:10.1038/nature11919
  131. 131. Xu Q, Seeger FH, Castillo J, Iekushi K, Boon RA, Farcas R, et al. Micro-RNA-34a contributes to the impaired function of bone marrow-derived mononuclear cells from patients with cardiovascular disease. J Am Coll Cardiol. 2012;59(23):2107-17. doi:10.1016/j.jacc.2012.02.033
  132. 132. Bernardo BC, Gao XM, Winbanks CE, Boey EJ, Tham YK, Kiriazis H, et al. Therapeutic inhibition of the miR-34 family attenuates pathological cardiac remodeling and improves heart function. Proc Natl Acad Sci U S A. 2012;109(43):17615-20. doi:10.1073/pnas.1206432109
  133. 133. Aranha MM, Santos DM, Sola S, Steer CJ, Rodrigues CM. miR-34a regulates mouse neural stem cell differentiation. PLoS One. 2011;6(8):e21396. doi:10.1371/journal.pone.0021396
  134. 134. Dombkowski AA, Batista CE, Cukovic D, Carruthers NJ, Ranganathan R, Shukla U, et al. Cortical tubers: windows into dysregulation of epilepsy risk and synaptic signaling genes by microRNAs. Cerebral Cortex. 2016;26(3):1059-71. doi:10.1093/cercor/bhu276
  135. 135. Gorter JA, Iyer A, White I, Colzi A, van Vliet EA, Sisodiya S, et al. Hippocampal subregion-specific microRNA expression during epileptogenesis in experimental temporal lobe epilepsy. Neurobiol Dis. 2014;62:508-20. doi:10.1016/j.nbd.2013.10.026
  136. 136. Guo J, Wang H, Wang Q, Chen Y, Chen S. Expression of p-CREB and activity-dependent miR-132 in temporal lobe epilepsy. Int J Clin Exp Med. 2014;7(5):1297-306. doi:1940-5901/IJCEM0000469
  137. 137. Peng J, Omran A, Ashhab MU, Kong H, Gan N, He F, et al. Expression patterns of miR-124, miR-134, miR-132 and miR-21 in an immature rat model and children with mesial temporal lobe epilepsy. J Mol Neurosci. 2013;50(2):291-7. doi:10.1007/s12031-013-9953-3
  138. 138. Song YJ, Tian XB, Zhang S, Zhang YX, Li X, Li D, et al. Temporal lobe epilepsy induces differential expression of hippocampal miRNAs including let-7e and miR-23a/b. Brain Res. 2011;1387:134-40. doi:10.1016/j.brainres.2011.02.073
  139. 139. Hu K, Xie Y-Y, Zhang C, Ouyang D-S, Long H-Y, Sun D-N, et al. MicroRNA expression profile of the hippocampus in a rat model of temporal lobe epilepsy and miR-34a-targeted neuroprotection against hippocampal neurone cell apoptosis post-status epilepticus. BMC Neurosci. 2012;13(1):1. doi:10.1186/1471-2202-13-115
  140. 140. Haramati S, Navon I, Issler O, Ezra-Nevo G, Gil S, Zwang R, et al. MicroRNA as repressors of stress-induced anxiety: the case of amygdalar miR-34. J Neurosci. 2011;31(40):14191-203. doi:10.1523/jneurosci.1673-11.2011
  141. 141. Liu N, Landreh M, Cao K, Abe M, Hendriks GJ, Kennerdell JR, et al. The microRNA miR-34 modulates ageing and neurodegeneration in Drosophila. Nature. 2012;482(7386):519-23. doi:10.1038/nature10810
  142. 142. Choi SE, Kemper JK. Regulation of SIRT1 by microRNAs. Mol Cells. 2013;36(5):385-92. doi:10.1007/s10059-013-0297-1
  143. 143. Zhuo M, Holtzman DM, Li Y, Osaka H, DeMaro J, Jacquin M, et al. Role of tissue plasminogen activator receptor LRP in hippocampal long-term potentiation. J Neurosci. 2000;20(2):542-9. Retrieved from [Accessed 2016-08-15].
  144. 144. Orth K, Madison EL, Gething M-J, Sambrook JF, Herz J. Complexes of tissue-type plasminogen-activator and its serpin inhibitor plasminogen activator inhibitor type 1 are internalized by means of the low density lipoprotein receptor-related protein/a2-macroglobulin receptor. Cell Biol. 1992;89:7422-6. Retrieved from [Accessed 2016-08-15].
  145. 145. Bodiga VL, Bodiga S. Renin angiotensin system in cognitive function and dementia. Asian J Neurosci. 2013;2013:1-18. doi:10.1155/2013/102602
  146. 146. ElAli A, Bordeleau M, Thériault P, Filali M, Lampron A, Rivest S. Tissue-plasminogen activator attenuates Alzheimer’s disease-related pathology development in APPswe/PS1 mice. Neuropsychopharmacology. 2015;41(5):1297-307. doi:10.1038/npp.2015.279
  147. 147. Cabrera-Fuentes HA, Alba-Alba C, Aragones J, Bernhagen J, Boisvert WA, Botker HE, et al. Meeting report from the 2nd International Symposium on New Frontiers in Cardiovascular Research. Protecting the cardiovascular system from ischemia: between bench and bedside. Basic Res Cardiol. 2016;111(1):7. doi:10.1007/s00395-015-0527-0
  148. 148. Sweeney MD, Ayyadurai S, Zlokovic BV. Pericytes of the neurovascular unit: key functions and signaling pathways. Nat Neurosci. 2016;19(6):771-83. doi:10.1038/nn.4288
  149. 149. Zhao Z, Nelson AR, Betsholtz C, Zlokovic BV. Establishment and dysfunction of the blood-brain barrier. Cell. 2015;163(5):1064-78. doi:10.1016/j.cell.2015.10.067
  150. 150. Saugstad JA. Non-coding RNAs in stroke and neuroprotection. Front Neurol. 2015;6:50. doi:10.3389/fneur.2015.00050
  151. 151. van Empel VP, De Windt LJ, da Costa Martins PA. Circulating miRNAs: reflecting or affecting cardiovascular disease? Curr Hypertens Rep. 2012;14(6):498-509. doi:10.1007/s11906-012-0310-7
  152. 152. Yin KJ, Hamblin M, Chen YE. Non-coding RNAs in cerebral endothelial pathophysiology: emerging roles in stroke. Neurochem Int. 2014;77:9-16. doi:10.1016/j.neuint.2014.03.013
  153. 153. Pritchard CC, Cheng HH, Tewari M. MicroRNA profiling: approaches and considerations. Nat Rev Genet. 2012;13(5):358-69. doi:10.1038/nrg3198
  154. 154. Benes V, Castoldi M. Expression profiling of microRNA using real-time quantitative PCR, how to use it and what is available. Methods. 2010;50(4):244-9. doi:10.1016/j.ymeth.2010.01.026
  155. 155. van Rooij E. The art of microRNA research. Circ Res. 2011;108(2):219-34. doi:10.1161/CIRCRESAHA.110.227496
  156. 156. Mestdagh P, Hartmann N, Baeriswyl L, Andreasen D, Bernard N, Chen C, et al. Evaluation of quantitative miRNA expression platforms in the microRNA quality control (miRQC) study. Nat Methods. 2014;11(8):809-15. doi:10.1038/nmeth.3014
  157. 157. Redshaw N, Wilkes T, Whale A, Cowen S, Huggett J, Foy CA. A comparison of miRNA isolation and RT-qPCR technologies and their effects on quantification accuracy and repeatability. Biotechniques. 2013;54(3):155-64. doi:10.2144/000114002
  158. 158. Hunt EA, Broyles D, Head T, Deo SK. MicroRNA detection: current technology and research strategies. Annu Rev Anal Chem. 2015;8:217-37. doi:10.1146/annurev-anchem-071114-040343
  159. 159. Zheng XH, Cui C, Zhou XX, Zeng YX, Jia WH. Centrifugation: an important pre-analytic procedure that influences plasma microRNA quantification during blood processing. Chin J Cancer. 2013;32(12):667-72. doi:10.5732/cjc.012.10271
  160. 160. Cheng L, Sharples RA, Scicluna BJ, Hill AF. Exosomes provide a protective and enriched source of miRNA for biomarker profiling compared to intracellular and cell-free blood. J Extracell Vesicles. 2014;3:23743. doi:10.3402/jev.v3.23743
  161. 161. Garzon R, Marcucci G, Croce CM. Targeting microRNAs in cancer: rationale, strategies and challenges. Nat Rev Drug Discov. 2010;9(10):775-89. doi:10.1038/nrd3179
  162. 162. Deiuliis J, Mihai G, Zhang J, Taslim C, Varghese JJ, Maiseyeu A, et al. Renin-sensitive microRNAs correlate with atherosclerosis plaque progression. J Hum Hypertens. 2013;28(4):251-8. doi:10.1038/jhh.2013.97
  163. 163. Thomas M, Lieberman J, Lal A. Desperately seeking microRNA targets. Nat Struct Mol Biol. 2010;17(10):1169-74. doi:10.1038/nsmb.1921
  164. 164. Day JJ, Sweatt JD. Epigenetic mechanisms in cognition. Neuron. 2011;70(5):813-29. doi:10.1016/j.neuron.2011.05.019
  165. 165. Landry CD, Kandel ER, Rajasethupathy P. New mechanisms in memory storage: piRNAs and epigenetics. Trends Neurosci. 2013;36(9):535-42. doi:10.1016/j.tins.2013.05.004
  166. 166. Boissonneault V, Plante I, Rivest S, Provost P. MicroRNA-298 and microRNA-328 regulate expression of mouse β-amyloid precursor protein-converting enzyme 1. J Biological Chem. 2009;284(4):1971-81. doi:10.1074/jbc.M807530200

Written By

Jose Gerardo-Aviles, Shelley Allen and Patrick Gavin Kehoe

Submitted: May 24th, 2016 Reviewed: November 28th, 2016 Published: July 12th, 2017