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Biochemistry, Genetics and Molecular Biology » "Protein Phosphorylation", book edited by Claude Prigent, ISBN 978-953-51-3626-2, Print ISBN 978-953-51-3625-5, Published: November 29, 2017 under CC BY 3.0 license. © The Author(s).

Chapter 4

Biological Consequences of Priming Phosphorylation in Cancer Development

By Katsuhiko Aoki and Kiyotsugu Yoshida
DOI: 10.5772/intechopen.70039

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Overview

Schematic illustration of multisite phosphorylation mediated by a priming kinase and a processive kinase.
Figure 1. Schematic illustration of multisite phosphorylation mediated by a priming kinase and a processive kinase.
Consensus sequence of priming kinases and processive kinases. (E,D)n denotes acidic amino acids cluster; X denotes any amino acid and S/T denotes Ser or Thr. CK1 recognizes the negatively charged amino acid cluster. DYRK1A is a proline- and arginine-directed kinase. DYRK2 is a proline-directed kinase. GSK3 typically phosphorylates “primed” substrate that is pre-phosphorylated by a priming kinase. CK1 also behaves as a phosphate-directed processive kinase.
Figure 2. Consensus sequence of priming kinases and processive kinases. (E,D)n denotes acidic amino acids cluster; X denotes any amino acid and S/T denotes Ser or Thr. CK1 recognizes the negatively charged amino acid cluster. DYRK1A is a proline- and arginine-directed kinase. DYRK2 is a proline-directed kinase. GSK3 typically phosphorylates “primed” substrate that is pre-phosphorylated by a priming kinase. CK1 also behaves as a phosphate-directed processive kinase.
Schematic diagram of NFAT translocation. DYRK1A acts as an export kinase in the nucleus. DYRK2 acts as a maintain kinase in the cytoplasm. These kinases mediate the priming phosphorylation of NFAT proteins. Fully phosphorylated NFAT proteins are sequestered in cytoplasm. Increased intracellular Ca2+ levels activate the calmodulin (CaM)/calcineurin (CN) phosphatase complex. Dephosphorylated NFAT proteins relocate into nucleus and promote gene transcription.
Figure 3. Schematic diagram of NFAT translocation. DYRK1A acts as an export kinase in the nucleus. DYRK2 acts as a maintain kinase in the cytoplasm. These kinases mediate the priming phosphorylation of NFAT proteins. Fully phosphorylated NFAT proteins are sequestered in cytoplasm. Increased intracellular Ca2+ levels activate the calmodulin (CaM)/calcineurin (CN) phosphatase complex. Dephosphorylated NFAT proteins relocate into nucleus and promote gene transcription.
Consensus sequence of phosphodegron motif. These phosphodegron motifs are created by several priming kinases such as DYRK2 and processive kinase GSK3. Underlined sequence indicates the canonical sequence of β-TRCP and FBW7. Loss of priming phosphorylation leads to dysgenesis of phosphodegron and results in stabilization of their target proteins.
Figure 4. Consensus sequence of phosphodegron motif. These phosphodegron motifs are created by several priming kinases such as DYRK2 and processive kinase GSK3. Underlined sequence indicates the canonical sequence of β-TRCP and FBW7. Loss of priming phosphorylation leads to dysgenesis of phosphodegron and results in stabilization of their target proteins.
Regulation of GSK3 activity and cellular status. GSK3 is constitutively active in quiescent cells. Stimulation of cells with insulin, growth factors or nutrients causes inactivation of GSK3 through several kinases belonging to each signaling cascade. These GSK3 inactivating kinases phosphorylate the N-terminal serine residue of GSK3 and create a primed pseudosubstrate that binds to catalytic site and inhibits the kinase activity.
Figure 5. Regulation of GSK3 activity and cellular status. GSK3 is constitutively active in quiescent cells. Stimulation of cells with insulin, growth factors or nutrients causes inactivation of GSK3 through several kinases belonging to each signaling cascade. These GSK3 inactivating kinases phosphorylate the N-terminal serine residue of GSK3 and create a primed pseudosubstrate that binds to catalytic site and inhibits the kinase activity.
Canonical Wnt signaling pathway. (A) Schematic representation of constitutive degradation of β-catenin mediated by the destruction complex and SCFβ-TRCP complex in resting cell. (B) Upon Wnt signaling, β-catenin is stabilized by sequestration and inactivation of destruction complex at cell membrane. It is known that the deficient of CK1α in gut epithelium shows a lot of the features of human colorectal tumors in addition to β-catenin stabilization and strong Wnt signal activation.
Figure 6. Canonical Wnt signaling pathway. (A) Schematic representation of constitutive degradation of β-catenin mediated by the destruction complex and SCFβ-TRCP complex in resting cell. (B) Upon Wnt signaling, β-catenin is stabilized by sequestration and inactivation of destruction complex at cell membrane. It is known that the deficient of CK1α in gut epithelium shows a lot of the features of human colorectal tumors in addition to β-catenin stabilization and strong Wnt signal activation.
Wnt signaling stabilizes the GSK3 target proteins. Wnt signaling promotes the signalosome formation via priming phosphorylation of C-terminal tail of LRP5/6 and oligomerization of Dvl. The signalosome sequesters a fraction of cytosolic GSK3 into multivesicular bodies. Consequently, accumulation of GSK3 substrates including oncogenic proteins is caused by a loss of phosphodegron formation.
Figure 7. Wnt signaling stabilizes the GSK3 target proteins. Wnt signaling promotes the signalosome formation via priming phosphorylation of C-terminal tail of LRP5/6 and oligomerization of Dvl. The signalosome sequesters a fraction of cytosolic GSK3 into multivesicular bodies. Consequently, accumulation of GSK3 substrates including oncogenic proteins is caused by a loss of phosphodegron formation.

Biological Consequences of Priming Phosphorylation in Cancer Development

Katsuhiko Aoki and Kiyotsugu Yoshida
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Abstract

Multisite phosphorylations on a single polypeptide mediated by protein kinase(s) are commonly observed. In some cases, hierarchical phosphorylations occur when first priming event triggers second processive phosphorylation. Hierarchal multisite phosphorylation that is mediated by a priming kinase and a processive kinase is a fail-safe system that accurately regulates physiological processes, including cell cycle progression, survival, migration, metabolism, differentiation and stem cell renewal. Here, we summarize the findings of cancer-associated priming kinases (CK1 and DYRK family) and processive kinase (GSK3). GSK3 has an unusual ability to accurately regulate the wide variety of cellular processes via the priming phosphorylation of its substrates. Therefore, dysregulation of priming phosphorylation gives rise to pathological disorders such as cancer.

Keywords: priming phosphorylation, multisite phosphorylation, hierarchical phosphorylation, priming kinase, CK1, DYRK1A, DYRK2, processive kinase, GSK3, NFAT signaling, Wnt signaling, β-catenin, SCF, β-TRCP, FBW7, LRP signalosome, protein stability, cancer

1. Introduction

Protein phosphorylation is the most frequent post-translational modification that regulates the function, interaction and stability of various proteins. Multisite phosphorylations on a single polypeptide, which are mediated by protein kinase(s), are commonly observed. In some cases, hierarchical phosphorylations occur when first phosphorylation event triggers second subsequent phosphorylation. Here, such a first phosphorylation is called as “priming phosphorylation.” Priming phosphorylation is mediated by “priming kinase” and serial phosphorylation is mediated by “processive kinase” (Figure 1).

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Figure 1.

Schematic illustration of multisite phosphorylation mediated by a priming kinase and a processive kinase.

Processive kinases, such as glycogen synthase kinase 3 (GSK3), are ubiquitously expressed in mammalian tissues and involved in numerous cellular processes. In this context, priming kinases provide a basis for selective action of the individual cellular process regulated by processive kinases.

Hierarchical multisite phosphorylations by the priming kinase and the processive kinase are the fail-safe mechanism that accurately regulates physiological processes, including cell cycle progression, survival, migration, metabolism, differentiation and stem cell renewal. Therefore, loss of priming phosphorylation caused by impairment of priming kinases gives rise to pathological disorders, such as cancer.

2. Priming kinases

2.1. Casein kinase 1 (CK1)

The casein kinase 1 (CK1) family is evolutionary conserved serine/threonine protein kinases that are ubiquitously expressed in eukaryotic organisms from yeast to human [1]. In human, six CK1 isoforms (α, γ1, γ2, γ3, δ and ε) are encoded by distinct genes. These isoforms differ in length and sequence of N-terminal and C-terminal domain [2, 3].

The name casein kinase arose from the protein kinase activity using casein as an in vitro substrate [4]. Because casein is a highly phosphorylated protein, the casein kinase was initially characterized by a phosphate-directed protein kinase [5, 6]. However, it became evident that CK1 does not only phosphorylate phospho-primed substrates but also displays a prominent phosphorylation activity targeting the site that contains cluster of acidic amino acids, immediately N-terminal (−1 to −5) of the phospho-acceptor site [79]. The canonical consensus sequence for CK1 is shown in Figure 2.

media/F2.png

Figure 2.

Consensus sequence of priming kinases and processive kinases. (E,D)n denotes acidic amino acids cluster; X denotes any amino acid and S/T denotes Ser or Thr. CK1 recognizes the negatively charged amino acid cluster. DYRK1A is a proline- and arginine-directed kinase. DYRK2 is a proline-directed kinase. GSK3 typically phosphorylates “primed” substrate that is pre-phosphorylated by a priming kinase. CK1 also behaves as a phosphate-directed processive kinase.

Members of the CK1 family are ubiquitously expressed but their expression levels differ in tissue and cell type [1012]. Recently, an increasing number of substrate proteins have been identified, which are phosphorylated by CK1 family in vitro and in vivo [2, 13, 14]. According to a global weblogo analysis to a database of 35,000 non-redundant phosphosites, CK1 targets are responsible for the generation of 9.5% of the human phosphoproteome [15].

The wide range of substrates suggests that the members of CK1 family regulate diverse and important cellular functions. For instance, they are involved in Wnt signaling, Hedgehog signaling, Hippo signaling, neurodegenerative disease, circadian rhythms, vesicular trafficking, cytoskeleton dynamics, nuclear localization, DNA processing and repair, apoptosis, cell division, proliferation and differentiation [2, 13, 14, 16]. Consequently, deregulation or dysfunction of CK1 in these pathways responsible for growth, proliferation, and apoptosis may result in pathological condition, such as tumorigenesis [3, 17, 18]. CK1δ and CK1ε isoforms are overexpressed and activated in many tumor types, such as colon and pancreatic cancers [19, 20]. By contrast, the downregulation of CK1α leads to increased proliferation and invasive growth of melanoma cells [21, 22].

2.2. Dual specificity tyrosine phosphorylation-regulated kinases (DYRKs)

Dual specificity tyrosine phosphorylation-regulated kinase (DYRK) family is an evolutionally conserved eukaryotic protein kinases belong to CMGC protein kinase group [23, 24]. In human, five DYRK members (DYRK1A, DYRK1B, DYRK2, DYRK3 and DYRK4) are encoded by distinct genes [25].

Their kinase activity depends upon the autophosphorylation of a tyrosine residue in activation loop of catalytic domain [26, 27]. The autophosphorylation of tyrosine is an intramolecular event that is mediated by a short-lived translational intermediate of itself [2830]. Once phosphorylated on the tyrosine residue, DYRKs lose tyrosine kinase ability and retain only serine/threonine kinase ability. Although DYRKs are potentially proline-directed kinase, they differ in their target recognition sequence and its preference for an arginine residue is a feature of DYRK1A but not of DYRK2 and DYRK4 [3134]. The canonical consensus sequence for DYRK1A and DYRK2 is shown in Figure 2.

With some exceptions [3537], DYRK1A and DYRK2 have been characterized as a potential tumor suppressor [3849]. In contrast, DYRK1B (also known MIRK), closely related to DYRK1A, have been characterized as a positive regulator of cancer cell survival [5061]. It is still not known to the details of the biological functions for DYRK3 and DYRK4.

Human DYRK1A is the most well-characterized member in the DYRK family [62, 63] because the gene is localized in the down syndrome (DS) critical region in chromosome 21 [6467]. In mouse, DYRK1A is essential for embryonic development, especially in the nervous systems, and unbalanced gene dosage causes developmental delay and abnormal brain morphology [6875]. In neuronal progenitor cells, overexpression of DYRK1A bring to the attenuation of cell proliferation that promotes the switch to a quiescent state or differentiation. DYRK1A mediates direct phosphorylation of p53 at Ser-15 that leads to the induction of p53 target genes, such as p21CIP1, and impaired G1/G0-S phase transition [76].

It is known that individuals with DS have a significantly reduced incidence of solid tumors [7779]. DS model mouse exhibits that considerable growth protection against transplantation of allogeneic tumors is caused by a deficit in tumor angiogenesis arising from suppression of nuclear factor of activated T cells (NFAT) transcriptional regulator pathway [38]. DYRK1A phosphorylates NFAT proteins in nucleus, thereby priming the subsequent phosphorylation by additional kinases (GSK3 and CK1), then fully phosphorylated NFAT proteins are exported from the nucleus to the cytoplasm (Figure 3). Cytoplasmic accumulation of NFAT proteins represses the NFAT pathway associated with tumor progression [80]. Paradoxically, children with DS have a remarkably increased risk of developing leukemias, including most types of acute megakaryoblastic leukemia (AMKL) and acute lymphoblastic leukemia (ALL). It has been suggested that DYRK1A is also a potent AMKL-promoting gene that modulates megakaryoblastic expansion through the inhibition of the NFAT pathway [35].

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Figure 3.

Schematic diagram of NFAT translocation. DYRK1A acts as an export kinase in the nucleus. DYRK2 acts as a maintain kinase in the cytoplasm. These kinases mediate the priming phosphorylation of NFAT proteins. Fully phosphorylated NFAT proteins are sequestered in cytoplasm. Increased intracellular Ca2+ levels activate the calmodulin (CaM)/calcineurin (CN) phosphatase complex. Dephosphorylated NFAT proteins relocate into nucleus and promote gene transcription.

Although precise regulation of NFAT pathway is essential for vertebrate development and function, NFAT isoforms are overexpressed and activated in human solid tumors and leukemias. This aberrant expression of NFAT proteins leads to the induction of the target genes that promote malignant phenotype that is associated with tumor progression, such as proliferation, survival, migration and invasion [8082]. In the basal state, NFAT proteins are sequestered and inactivated as a phosphorylated form in the cytoplasm. DYRK1A acts as an export kinase that phosphorylates NFAT proteins inside the nucleus and induces its relocation to the cytoplasm. As a counterpart of export kinase, DYRK2 acts as a maintenance kinase that phosphorylates in the cytoplasm, where they keep NFAT proteins in a phosphorylated state, and prevents their translocation to the nucleus (Figure 3). DYRK1A and DYRK2 can directly phosphorylate the conserved SP3 motif of the NFAT regulatory domain and thereby can prime for the subsequent phosphorylation by GSK3 and/or CK1 [83].

Under normal conditions, DYRK2 is predominantly expressed in the cytoplasm and constitutively degraded by MDM2 ubiquitin ligase in the nucleus. Upon exposure to genotoxic stress, ATM protein kinase phosphorylates DYRK2 at Thr-33 and Ser-369. As a result, DYRK2 enable to escape from MDM2 and to induce the kinase activity toward p53 at Ser-46 in the nucleus. Phosphorylation of Ser-46 following severe DNA damage increases the transcriptional activity of pro-apoptotic genes [84, 85]. The other functional role of DYRK2 in DNA damage response may be link to DNA double-strand break repair pathway [86].

DYRK2 was found to be mutated in breast and central nervous system tumors, in nonsense and missense mutation, respectively [87, 88]. Loss of function of DYRK2 in cancer cells accelerated cell proliferation due to stabilization of oncogenic transcription factors, c-Jun and c-Myc [89]. This stabilization is caused by the loss of priming phosphorylation that is necessary to generate a phosphodegron that leads to subsequent SCF (Skp1-Cullin1-F-box protein) ubiquitin ligase-mediated degradation. Snail, a zinc finger protein to promote epithelial-mesenchymal transitions (EMT), is stabilized by the DYRK2 knockdown, probably in the same fashion as c-Jun/c-Myc, and allows cancer cells to represent loss of epithelial features and gain of invasiveness [90, 91] (Figure 4). Moreover, it is recently demonstrated that impairment of DYRK2 augments cancer stem-like traits of breast cancer cells [92].

media/F4.png

Figure 4.

Consensus sequence of phosphodegron motif. These phosphodegron motifs are created by several priming kinases such as DYRK2 and processive kinase GSK3. Underlined sequence indicates the canonical sequence of β-TRCP and FBW7. Loss of priming phosphorylation leads to dysgenesis of phosphodegron and results in stabilization of their target proteins.

2.3. Other priming kinases

It is also known that cAMP-dependent kinase (PKA), AMP-activated protein kinase (AMPK), cyclin-dependent kinase 5 (CDK5), DNA-dependent protein kinase (DNA-PK), calcium and calmodulin-dependent protein kinase II (CAMKII) and mitogen-activated protein kinases (MAPKs) can act as priming kinases for GSK3 [93]. CDK1 functions as a priming kinase for polo-like kinase 1 (PLK1) that is a key regulator of cell cycle progression [94, 95].

3. Processive kinases

Phosphate-directed protein kinases, such as CK1, CK2 [96, 97] and GSK3, function as the processive kinases. CK1 not only act as a priming kinase but also proposed as a processive kinase (Figure 2). Here, we focus on GSK3.

GSK3 was originally identified as a protein kinase that negatively regulates glycogen synthesis by phosphorylating and inactivating glycogen synthase [98]. In mammals, two GSK3 isoforms (GSK3α and GSK3β) are encoded by distinct genes [99]. These two GSK3 isoforms, which are expressed ubiquitously in tissues, have many overlapping functions, but they do not always compensate for each other.

Substrate recognition by GSK3 is an unusual preference for target proteins that are priorly phosphorylated at an approximately 4 residues C-terminal to GSK3 target site. The canonical consensus sequence for GSK3 is shown in Figure 2. Although priming phosphorylation is not stringently required for the recognition of GSK3, the efficiency of substrate phosphorylation is greatly increased by priming phosphorylation [100]. This substrate recognition mechanism means that GSK3 reduces crosstalk among different signaling pathways. In other words, GSK3 must be colocalized with the priming kinase that is involved in the specific signaling pathway. For example, in NFAT pathway, processive kinases GSK3 and CK1 are distributed throughout the entire cell. However, priming kinases DYRK1A and DYRK2 are localized to specific location, which is nuclear and cytoplasm. GSK3 thus has an unusual ability to accurately regulate the wide variety of cellular processes. We now know that the enzyme is a key regulator of various cellular processes, such as Wnt signaling pathway, hedgehog signaling pathway, NFAT pathway, mTOR pathway, EMT, cell cycle and proliferation regulation. Large number of proteins involved in a wide spectrum of cellular processes have been proposed as putative substrates of GSK3 [93]. It is noteworthy that the consensus sequence of GSK3 is included in the “phosphodegron motif” that is recognized by SCF ubiquitin-ligase complex (Figure 4). Therefore, most GSK3-targets receive the proteasomal degradation that relies on a phosphodegron created by dual phosphorylation and mediated by priming kinase and GSK3 [101, 102].

Unlike most protein kinases, GSK3 is constitutively active in resting cells, and its activity can be inhibited by a variety of extracellular signals that typically induce cell survival and growth, such as insulin, growth factors and nutrients. Numerous stimuli lead to activate the GSK3 inactivating kinase pathways, such as PI3K-Akt and mTOR pathway. These kinases lead to inactivation of GSK3 through the phosphorylation of N-terminal serine residue. Phosphorylated N-terminal segment creates a primed pseudosubstrate that intramolecularly binds to substrate-binding pocket (Figure 5). Inactivation mechanism of GSK3 by the Wnt signaling pathway is mentioned below.

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Figure 5.

Regulation of GSK3 activity and cellular status. GSK3 is constitutively active in quiescent cells. Stimulation of cells with insulin, growth factors or nutrients causes inactivation of GSK3 through several kinases belonging to each signaling cascade. These GSK3 inactivating kinases phosphorylate the N-terminal serine residue of GSK3 and create a primed pseudosubstrate that binds to catalytic site and inhibits the kinase activity.

4. Priming phosphorylation regulates cellular processes

4.1. Wnt signaling pathway

Wnt signaling pathway plays crucial roles in proliferation and differentiation of stem and progenitor cells during embryogenesis and adult tissue homeostasis [103105]. Aberration of this signaling is implicated in a variety of human cancers [106109].

The β-catenin-dependent Wnt pathway is commonly referred to as the canonical pathway, which is characterized by the stabilization and the nuclear translocation of transcriptional co-activator β-catenin.

In the absence of Wnt ligand, β-catenin is sequestered in the cytoplasm and constantly degraded by the action of a “destruction complex,” which is composed of adenomatous polyposis coli (Apc), Axin, CK1α and GSK3 [110114]. The degradation of β-catenin is based on two steps regulated by priming phosphorylation. (1) CK1α mediates the priming phosphorylation of Apc that leads to sequential phosphorylation by GSK3, and this phosphorylation enhances the binding affinity to β-catenin [115118]. (2) CK1α leads to phosphorylation of β-catenin on Ser-45, which creates a priming site for GSK3 [119]. Then, GSK3 phosphorylates Thr-41, Ser-37, and Ser-33 in a sequential manner [120, 121]. Priming-dependent phosphorylation by GSK3 generates the consensus motif of β-transducin repeat-containing protein (β-TRCP) recognition site at the N-terminal domain of β-catenin. After being released from the destruction complex, phosphorylated β-catenin is recognized by SCFβ-TRCP E3 ubiquitin ligase and degraded by the ubiquitin-proteasome pathway [122125] (Figure 6).

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Figure 6.

Canonical Wnt signaling pathway. (A) Schematic representation of constitutive degradation of β-catenin mediated by the destruction complex and SCFβ-TRCP complex in resting cell. (B) Upon Wnt signaling, β-catenin is stabilized by sequestration and inactivation of destruction complex at cell membrane. It is known that the deficient of CK1α in gut epithelium shows a lot of the features of human colorectal tumors in addition to β-catenin stabilization and strong Wnt signal activation.

From a conditional knockout mouse model, the deficient of CK1α in gut epithelium shows a lot of the features of human colorectal tumors in addition to β-catenin stabilization and strong Wnt signal activation [126]. Additionally, a genome-wide, reporter-based, screening in human haploid cells reveal that CK1α is a critical negative regulator of canonical Wnt signaling pathway [127].

In the presence of Wnt ligand, β-catenin is stabilized by escaping from phosphorylation-mediated degradation and is translocated into the nucleus. After that, it binds to the T cell factor/lymphoid enhancer-binding factor (TCF/LEF) transcription factor and activates Wnt target gene expression. At this time, the function of destruction complex is suppressed by the priming phosphorylation-dependent manner (Figure 6).

Signaling of Wnt family requires the cell-surface receptors, frizzled (Fzd) that is related to the GPCR superfamily and low-density lipoprotein receptor-related protein 5/6 (LRP5/6) that is a single-span transmembrane receptor [128131]. Wnt-Fzd-LRP5/6 triple complex recruits a Fzd-associated scaffold protein, Dishevelled (Dvl) and triggers the membrane-associated clustering into ribosome-sized LRP signalosomes [132]. In turn, Dvl promotes phosphorylation of the cytoplasmic tail of LRP5/6 mediated by membrane-bound CK1γ and the phosphorylated LRP5/6 is followed by the recruitment of Axin away from the degradation complex [133136]. The phosphorylation sites of LRP5/6 contain five PPPSPxS motifs. Membrane-associated GSK3 phosphorylates the first Ser (or Thr) within these motifs and serves a priming site for the CK1-mediated phosphorylation [137, 138]. In this case, membrane-associated GSK3 acts as a priming kinase and CK1 acts as a processive kinase. The phosphorylated PPPSPxS repeats provide an optical-binding site for Axin and recruit cytoplasmic Axin-GSK3 complex to LRP signalosome [135, 137, 139]. Importantly, phosphorylated LRP5/6 cytoplasmic tail that creates a primed pseudosubstrate can directly inhibit GSK3 activity [138, 140142], suggesting that LRP signalosome formation may be an aggressive mechanism for sequestration of GSK3 activity from cytosol. Endocytosed signalosomes that colocalize with the late endosomal markers Rab7 and Vps4 mature into multivesicular bodies [143]. As a result of the LPR signalosomes formation, β-catenin protects from phosphorylation and escapes from ubiquitylation and proteasome degradation, which enables it to accumulate in the cytosol and nucleus. As it turns out, stabilized β-catenin binds TCF/LEF to initiate the cellular transcriptional program that is usually directs to proliferation, survival and inhibition of differentiation (Figure 7).

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Figure 7.

Wnt signaling stabilizes the GSK3 target proteins. Wnt signaling promotes the signalosome formation via priming phosphorylation of C-terminal tail of LRP5/6 and oligomerization of Dvl. The signalosome sequesters a fraction of cytosolic GSK3 into multivesicular bodies. Consequently, accumulation of GSK3 substrates including oncogenic proteins is caused by a loss of phosphodegron formation.

4.2. Priming phosphorylation regulates protein stability

The ubiquitin-proteasome system controls degradation of the majority of regulatory proteins, including transcription factors and protein kinases, that play key roles in tumorigenesis. E3 ubiquitin ligases determine the substrate specificity for given substrates. SCF E3 ubiquitin ligase is important for the recognition of specifically phosphorylated substrates. F-box protein, which is a subunit of SCF, mediates the recognition and binding of the phosphorylated substrate. In most cases, phosphorylated substrates have a short motif that is a recognition signal for F-box proteins, namely phosphodegron. Since the consensus sequence of GSK3 is corresponding to special phosphodegron motifs that are recognized by two subfamily of F-box protein FBW7 and β-TRCP, a lot of GSK3 targets phosphorylated by priming kinases receive the proteasomal degradation [93, 102]. It is known that FBW7 and β-TRCP are involved in cell cycle regulation and tumorigenesis by targeting proteins in these processes. Thus, priming phosphorylation to create the phosphodegron processed by GSK3 is presumed to be significant consequence for cancer development.

FBW7 is generally considered as a tumor suppressor because of its loss of function phenotype found in multiple type of human cancer. FBW7 recognizes a lot of oncogenic substrates, including cyclin E, c-Myc, c-Jun, Mcl-I, mTOR and Notch-1 [144]. Among these substrates, c-Myc, c-Jun and potentially mTOR are phosphorylated by DYRK2, which creates a priming site for GSK3 [89, 145]. Therefore, the loss of priming phosphorylation may denote the direction of cancer progression in the GSK3-FBW7 axis. On the other hand, β-TRCP contributes to the degradation of β-catenin and snail, which is implicated in human cancer progression. Of note, both are phosphorylated by priming kinases [146]. In contrast to FBW7, β-TRCP is regarded as an oncogene on account of the fact that higher expression of β-TRCP is validated in various type of human cancer. Furthermore, overexpression of β-TRCP exerts its tumorigenic activity in mouse model [147] and mutations in β-TRCP are uncommon in human cancers [144]. However, due to the fact that β-TRCP substrates include both oncogene products such as β-catenin and tumor suppressors such as IκB, an inhibitor of NF-κB, it is difficult to characterize the function of β-TRCP as an oncogene or a tumor suppressor. In this context, the contribution of β-TRCP to tumor progression may become altered in the tissue specific- or cellular context-dependent manner.

Bioinformatic analysis reveals that about 20% of the human proteome contains three or more putative GSK3 phosphorylation sites. As mentioned above, LRP6 signalosome induced by the canonical Wnt signal sequesters GSK3 into multivesicular bodies and the sequestration results in the cytosolic GSK3 activity level decreased to below 40%. Accordingly, the half-life of numerous cellular proteins including GSK3 substrates is extended [143]. In proliferating cells, Wnt signaling peaks in the G2/M phase of cell cycle, and in this phase, G1 activators such as cyclin D1 and c-Myc are accumulated to progress the cell cycle [148, 149]. Moreover, depletion of GSK3 activity with a chemical inhibitor treatments or siRNA knockdown experiments stabilizes cellular proteins as similar to Wnt treatment [143]. This means that GSK3-dependent protein catabolism is more universal, beyond the cell cycle and Wnt signaling. Therefore, it is predicted that the dysregulation of priming phosphorylation influences the cellular protein homeostasis through the processive phosphorylation by GSK3. Priming kinase-GSK3-SCF axis emerges as a principal regulator of cancer development.

5. Conclusion

Hierarchical multisite phosphorylation by a priming kinase and a processive kinase is the fail-safe mechanism that accurately regulates the physiological processes, including cell cycle progression, survival, migration, metabolism, differentiation and stem cell renewal. Loss of priming phosphorylation caused by impairment of priming kinases, such as CK1 family and DYRK family, gives rise to pathological disorders as a result of the abnormal localization and/or half-life of cellular proteins. These priming kinases create the recognition site for further phosphorylation by the processive kinase, GSK3. The consensus sequence of GSK3 is corresponding to phosphodegron motif that is recognized by SCF ubiquitin-ligase complex. Therefore, a lot of GSK3 targets including oncogenes or tumor suppressors receive the proteasomal degradation that depends upon a phosphodegron. GSK3-dependent protein dissimilation is more universal, beyond the cell cycle and Wnt signaling. Consequently, priming kinase-GSK3-SCF axis manifests as a key regulator for cancer development.

References

1 - Manning G, Plowman GD, Hunter T, Sudarsanam S. Evolution of protein kinase signaling from yeast to man. Trends in Biochemical Sciences. 2002;27(10):514-520
2 - Knippschild U, Gocht A, Wolff S, Huber N, Löhler J, Stöter M. The casein kinase 1 family: Participation in multiple cellular processes in eukaryotes. Cellular Signalling. 2005;17(6): 675-689
3 - Knippschild U, Krüger M, Richter J, Xu P, García-Reyes B, Peifer C, et al. The CK1 family: Contribution to cellular stress response and its role in carcinogenesis. Frontiers in Oncology. 2014;19(4):96. DOI: 10.3389/fonc.2014.00096
4 - Kumar R, Tao M. Multiple forms of casein kinase from rabbit erythrocytes. Biochimica et Biophysica Acta. 1975;410(1):87-98
5 - Flotow H, Roach PJ. Synergistic phosphorylation of rabbit muscle glycogen synthase by cyclic AMP-dependent protein kinase and casein kinase I. Implications for hormonal regulation of glycogen synthase. The Journal of Biological Chemistry. 1989;264(16):9126-9128
6 - Flotow H, Graves PR, Wang AQ, Fiol CJ, Roeske RW, Roach PJ. Phosphate groups as substrate determinants for casein kinase I action. The Journal of Biological Chemistry. 1990;265(24):14264-14269
7 - Agostinis P, Pinna LA, Meggio F, Marin O, Goris J, Vandenheede JR, Merlevede W. A synthetic peptide substrate specific for casein kinase I. FEBS Letters. 1989;259(1):75-78
8 - Flotow H, Roach PJ. Role of acidic residues as substrate determinants for casein kinase I. The Journal of Biological Chemistry. 1991;266(6):3724-3727
9 - Pulgar V, Marin O, Meggio F, Allende CC, Allende JE, Pinna LA. Optimal sequences for non-phosphate-directed phosphorylation by protein kinase CK1 (casein kinase-1)–a re-evaluation. European Journal of Biochemistry. 1999;260(2):520-526.
10 - Tuazon PT, Traugh JA. Casein kinase I and II--multipotential serine protein kinases: Structure, function, and regulation. Advances in Second Messenger and Phosphoprotein Research 1991;23:123-164
11 - Löhler J, Hirner H, Schmidt B, Kramer K, Fischer D, Thal DR, et al. Immunohistochemical characterisation of cell-type specific expression of CK1delta in various tissues of young adult BALB/c mice. PLoS One. 2009;4(1):e4174. DOI: 10.1371/journal.pone.0004174
12 - Utz AC, Hirner H, Blatz A, Hillenbrand A, Schmidt B, Deppert W, et al. Analysis of cell type-specific expression of CK1 epsilon in various tissues of young adult BALB/c Mice and in mammary tumors of SV40 T-Ag-transgenic mice. Journal of Histochemistry and Cytochemistry. 2010;58(1):1-15. DOI: 10.1369/jhc.2009.954628
13 - Price MA. CKI, there's more than one: Casein kinase I family members in Wnt and Hedgehog signaling. Genes and Development. 2006;20(4):399-410
14 - Cheong JK, Virshup DM. Casein kinase 1: Complexity in the family. International Journal of Biochemistry & Cell Biology. 2011;43(4):465-469. DOI: 10.1016/j.biocel.2010.12.004
15 - Ruzzene M, Tosoni K, Zanin S, Cesaro L, Pinna LA. Protein kinase CK2 accumulation in “oncophilic” cells: Causes and effects. Molecular and Cellular Biochemistry. 2011;356(1-2):5-10. DOI: 10.1007/s11010-011-0959-2
16 - Cruciat CM. Casein kinase 1 and Wnt/β-catenin signaling. Current Opinion in Cell Biology. 2014;31:46-55. DOI: 10.1016/j.ceb.2014.08.003
17 - Modak C, Chai J. Potential of casein kinase I in digestive cancer screening. World Journal of Gastrointestinal Oncology. 2009;1(1):26-33. DOI: 10.4251/wjgo.v1.i1.26
18 - Schittek B, Sinnberg T. Biological functions of casein kinase 1 isoforms and putative roles in tumorigenesis. Molecular Cancer. 2014;13:231. DOI: 10.1186/1476-4598-13-231
19 - Umar S, Wang Y, Morris AP, Sellin JH. Dual alterations in casein kinase I-epsilon and GSK-3beta modulate beta-catenin stability in hyperproliferating colonic epithelia. American Journal of Physiology - Gastrointestinal and Liver Physiology. 2007;292(2):G599-G607
20 - Brockschmidt C, Hirner H, Huber N, Eismann T, Hillenbrand A, Giamas G, et al. Anti-apoptotic and growth-stimulatory functions of CK1 delta and epsilon in ductal adenocarcinoma of the pancreas are inhibited by IC261 in vitro and in vivo. Gut. 2008;57(6):799-806. DOI: 10.1136/gut.2007.123695
21 - Sinnberg T, Menzel M, Kaesler S, Biedermann T, Sauer B, Nahnsen S, et al. Suppression of casein kinase 1alpha in melanoma cells induces a switch in beta-catenin signaling to promote metastasis. Cancer Research. 2010;70(17):6999-7009. DOI: 10.1158/0008-5472.CAN-10-0645
22 - Sinnberg T, Wang J, Sauer B, Schittek B. Casein kinase 1α has a non-redundant and dominant role within the CK1 family in melanoma progression. BMC Cancer 2016;16:594. DOI: 10.1186/s12885-016-2643-0
23 - Becker W, Joost HG. Structural and functional characteristics of Dyrk, a novel subfamily of protein kinases with dual specificity. Progress in Nucleic Acid Research and Molecular Biology 1999;62:1-17
24 - Kannan N, Neuwald AF. Evolutionary constraints associated with functional specificity of the CMGC protein kinases MAPK, CDK, GSK, SRPK, DYRK, and CK2alpha. Protein Science. 2004;13(8):2059-2077
25 - Aranda S, Laguna A, de la Luna S. DYRK family of protein kinases: Evolutionary relationships, biochemical properties, and functional roles. FASEB Journal. 2011;25(2):449-462. DOI: 10.1096/fj.10-165837
26 - Kentrup H, Becker W, Heukelbach J, Wilmes A, Schürmann A, Huppertz C, et al. Dyrk, a dual specificity protein kinase with unique structural features whose activity is dependent on tyrosine residues between subdomains VII and VIII. The Journal of Biological Chemistry. 1996;271(7):3488-3495
27 - Himpel S, Panzer P, Eirmbter K, Czajkowska H, Sayed M, Packman LC, et al. Identification of the autophosphorylation sites and characterization of their effects in the protein kinase DYRK1A. Biochemical Journal. 2001;359(Pt 3):497-505
28 - Lochhead PA, Sibbet G, Morrice N, Cleghon V. Activation-loop autophosphorylation is mediated by a novel transitional intermediate form of DYRKs. Cell. 2005;121(6):925-936
29 - Kinstrie R, Luebbering N, Miranda-Saavedra D, Sibbet G, Han J, Lochhead PA, Cleghon V. Characterization of a domain that transiently converts class 2 DYRKs into intramolecular tyrosine kinases. Science Signaling. 2010;3(111):ra16. DOI: 10.1126/scisignal.2000579
30 - Han J, Miranda-Saavedra D, Luebbering N, Singh A, Sibbet G, Ferguson MA, Cleghon V. Deep evolutionary conservation of an intramolecular protein kinase activation mechanism. PLoS One. 2012;7(1):e29702. DOI: 10.1371/journal.pone.0029702
31 - Himpel S, Tegge W, Frank R, Leder S, Joost HG, Becker W. Specificity determinants of substrate recognition by the protein kinase DYRK1A. The Journal of Biological Chemistry. 2000;275(4):2431-2438
32 - Campbell LE, Proud CG. Differing substrate specificities of members of the DYRK family of arginine-directed protein kinases. FEBS Letters. 2002;510(1-2):31-36
33 - Papadopoulos C, Arato K, Lilienthal E, Zerweck J, Schutkowski M, Chatain N, et al. Splice variants of the dual specificity tyrosine phosphorylation-regulated kinase 4 (DYRK4) differ in their subcellular localization and catalytic activity. The Journal of Biological Chemistry. 2011;286(7):5494-5505. DOI: 10.1074/jbc.M110.157909
34 - Soundararajan M, Roos AK, Savitsky P, Filippakopoulos P, Kettenbach AN, Olsen JV, et al. Structures of Down syndrome kinases, DYRKs, reveal mechanisms of kinase activation and substrate recognition. Structure. 2013;21(6):986-996. DOI: 10.1016/j.str.2013.03.012
35 - Malinge S, Bliss-Moreau M, Kirsammer G, Diebold L, Chlon T, Gurbuxani S, Crispino JD. Increased dosage of the chromosome 21 ortholog Dyrk1a promotes megakaryoblastic leukemia in a murine model of Down syndrome. Journal of Clinical Investigation. 2012;122(3):948-962. DOI: 10.1172/JCI60455
36 - Pozo N, Zahonero C, Fernández P, Liñares JM, Ayuso A, Hagiwara M, et al. Inhibition of DYRK1A destabilizes EGFR and reduces EGFR-dependent glioblastoma growth. Journal of Clinical Investigation. 2013;123(6):2475-2487. DOI: 10.1172/JCI63623
37 - Guo X, Wang X, Wang Z, Banerjee S, Yang J, Huang L, Dixon JE. Site-specific proteasome phosphorylation controls cell proliferation and tumorigenesis. Nature Cell Biology. 2016;18(2):202-212. DOI: 10.1038/ncb3289
38 - Baek KH, Zaslavsky A, Lynch RC, Britt C, Okada Y, Siarey RJ, et al. Down's syndrome suppression of tumour growth and the role of the calcineurin inhibitor DSCR1. Nature. 2009;459(7250):1126-1130. DOI: 10.1038/nature08062
39 - Litovchick L, Florens LA, Swanson SK, Washburn MP, DeCaprio JA. DYRK1A protein kinase promotes quiescence and senescence through DREAM complex assembly. Genes and Development. 2011;25(8):801-813. DOI: 10.1101/gad.2034211
40 - Tschöp K, Conery AR, Litovchick L, Decaprio JA, Settleman J, Harlow E, Dyson N. A kinase shRNA screen links LATS2 and the pRB tumor suppressor. Genes and Development. 2011;25(8):814-830. DOI: 10.1101/gad.2000211
41 - Liu Q, Liu N, Zang S, Liu H, Wang P, Ji C, Sun X. Tumor suppressor DYRK1A effects on proliferation and chemoresistance of AML cells by downregulating c-Myc. PLoS One. 2014;9(6):e98853. DOI: 10.1371/journal.pone.0098853
42 - Yamashita S, Chujo M, Moroga T, Anami K, Tokuishi K, Miyawaki M, et al. DYRK2 expression may be a predictive marker for chemotherapy in non-small cell lung cancer. Anticancer Research. 2009;29(7):2753-2757
43 - Yamashita S, Chujo M, Tokuishi K, Anami K, Miyawaki M, Yamamoto S, Kawahara K. Expression of dual-specificity tyrosine-(Y)-phosphorylation-regulated kinase 2 (DYRK2) can be a favorable prognostic marker in pulmonary adenocarcinoma. Journal of Thoracic and Cardiovascular Surgery. 2009;138(6):1303-1308. DOI: 10.1016/j.jtcvs.2009.08.003
44 - Park JH, Park J, Choi JK, Lyu J, Bae MG, Lee YG, et al. Identification of DNA methylation changes associated with human gastric cancer. BMC Medical Genomics 2011;4:82. DOI: 10.1186/1755-8794-4-82
45 - Enomoto Y, Yamashita S, Yoshinaga Y, Fukami Y, Miyahara S, Nabeshima K, Iwasaki A. Downregulation of DYRK2 can be a predictor of recurrence in early stage breast cancer. Tumour Biology. 2014;35(11):11021-11025. DOI: 10.1007/s13277-014-2413-z
46 - Nomura S, Suzuki Y, Takahashi R, Terasaki M, Kimata R, Terasaki Y, et al. Dual-specificity tyrosine phosphorylation-regulated kinase 2 (DYRK2) as a novel marker in T1 high-grade and T2 bladder cancer patients receiving neoadjuvant chemotherapy. BMC Urology. 2015;15:53. DOI: 10.1186/s12894-015-0040-7
47 - Wang Y, Wu Y, Miao X, Zhu X, Miao X, He Y, et al. Silencing of DYRK2 increases cell proliferation but reverses CAM-DR in Non-Hodgkin's Lymphoma. International Journal of Biological Macromolecules 2015;81:809-817. DOI: 10.1016/j.ijbiomac.2015.08.067
48 - Zhang X, Xu P, Ni W, Fan H, Xu J, Chen Y, et al. Downregulated DYRK2 expression is associated with poor prognosis and oxaliplatin resistance in hepatocellular carcinoma. Pathology, Research and Practice. 2016;212(3):162-170. DOI: 10.1016/j.prp.2016.01.002
49 - Yan H, Hu K, Wu W, Li Y, Tian H, Chu Z, et al. Low expression of DYRK2 (Dual specificity tyrosine phosphorylation regulated kinase 2) correlates with poor prognosis in colorectal cancer. PLoS One. 2016;11(8):e0159954. DOI: 10.1371/journal.pone.0159954
50 - Friedman E. Mirk/Dyrk1B in cancer. Journal of Cellular Biochemistry. 2007;102(2):274-279
51 - Jin K, Park S, Ewton DZ, Friedman E. The survival kinase Mirk/Dyrk1B is a downstream effector of oncogenic K-ras in pancreatic cancer. Cancer Research. 2007;67(15):7247-7255
52 - Deng X, Ewton DZ, Friedman E. Mirk/Dyrk1B maintains the viability of quiescent pancreatic cancer cells by reducing levels of reactive oxygen species. Cancer Research. 2009;69(8):3317-3324. DOI: 10.1158/0008-5472.CAN-08-2903
53 - Jin K, Ewton DZ, Park S, Hu J, Friedman E. Mirk regulates the exit of colon cancer cells from quiescence. The Journal of Biological Chemistry. 2009;284(34):22916-22925. DOI: 10.1074/jbc.M109.035519
54 - Gao J, Zheng Z, Rawal B, Schell MJ, Bepler G, Haura EB. Mirk/Dyrk1B, a novel therapeutic target, mediates cell survival in non-small cell lung cancer cells. Cancer Biology and Therapy. 2009;8(17):1671-1679
55 - Yang C, Ji D, Weinstein EJ, Choy E, Hornicek FJ, Wood KB, et al. The kinase Mirk is a potential therapeutic target in osteosarcoma. Carcinogenesis. 2010;31(4):552-558. DOI: 10.1093/carcin/bgp330
56 - Hu J, Nakhla H, Friedman E. Transient arrest in a quiescent state allows ovarian cancer cells to survive suboptimal growth conditions and is mediated by both Mirk/dyrk1b and p130/RB2. International Journal of Cancer. 2011;129(2):307-318. DOI: 10.1002/ijc.25692
57 - Ewton DZ, Hu J, Vilenchik M, Deng X, Luk KC, Polonskaia A, et al. Inactivation of mirk/dyrk1b kinase targets quiescent pancreatic cancer cells. Molecular Cancer Therapeutics. 2011;10(11):2104-2114. DOI: 10.1158/1535-7163.MCT-11-0498
58 - Gao J, Yang X, Yin P, Hu W, Liao H, Miao Z, et al. The involvement of FoxO in cell survival and chemosensitivity mediated by Mirk/Dyrk1B in ovarian cancer. International Journal of Oncology. 2012;40(4):1203-1209. DOI: 10.3892/ijo.2011.1293
59 - Hu J, Deng H, Friedman EA. Ovarian cancer cells, not normal cells, are damaged by Mirk/Dyrk1B kinase inhibition. International Journal of Cancer. 2013;132(10):2258-2269. DOI: 10.1002/ijc.27917
60 - Tsioras K, Papastefanaki F, Politis PK, Matsas R, Gaitanou M. Functional Interactions between BM88/Cend1, Ran-binding protein M and Dyrk1B kinase affect cyclin D1 levels and cell cycle progression/exit in mouse neuroblastoma cells. PLoS One. 2013;8(11):e82172. DOI: 10.1371/journal.pone.0082172
61 - Gruber W, Hutzinger M, Elmer DP, Parigger T, Sternberg C, Cegielkowski L, et al. DYRK1B as therapeutic target in Hedgehog/GLI-dependent cancer cells with Smoothened inhibitor resistance. Oncotarget. 2016;7(6):7134-7148. DOI: 10.18632/oncotarget.6910
62 - Fernández-Martínez P, Zahonero C, Sánchez-Gómez P. DYRK1A: The double-edged kinase as a protagonist in cell growth and tumorigenesis. Molecular & Cellular Oncology. 2015;2(1):e970048. DOI: 10.4161/23723548.2014.970048
63 - Abbassi R, Johns TG, Kassiou M, Munoz L. DYRK1A in neurodegeneration and cancer: Molecular basis and clinical implications. Pharmacology and Therapeutics. 2015;151:87-98. DOI: 10.1016/j.pharmthera.2015.03.004
64 - Shindoh N, Kudoh J, Maeda H, Yamaki A, Minoshima S, Shimizu Y, Shimizu N. Cloning of a human homolog of the Drosophila minibrain/rat Dyrk gene from “the Down syndrome critical region” of chromosome 21. Biochemical and Biophysical Research Communications. 1996;225(1):92-99
65 - Guimerá J, Casas C, Pucharcòs C, Solans A, Domènech A, Planas AM, et al. A human homologue of Drosophila minibrain (MNB) is expressed in the neuronal regions affected in Down syndrome and maps to the critical region. Human Molecular Genetics. 1996;5(9):1305-1310
66 - Song WJ, Sternberg LR, Kasten-Sportès C, Keuren ML, Chung SH, Slack AC, et al. Isolation of human and murine homologues of the Drosophila minibrain gene: Human homologue maps to 21q22.2 in the Down syndrome “critical region”. Genomics. 1996;38(3):331-339
67 - Matsumoto N, Ohashi H, Tsukahara M, Kim KC, Soeda E, Niikawa N. Possible narrowed assignment of the loci of monosomy 21-associated microcephaly and intrauterine growth retardation to a 1.2-Mb segment at 21q22.2. The American Journal of Human Genetic. 1997;60(4):997-999
68 - Smith DJ, Stevens ME, Sudanagunta SP, Bronson RT, Makhinson M, Watabe AM, et al. Functional screening of 2 Mb of human chromosome 21q22.2 in transgenic mice implicates minibrain in learning defects associated with Down syndrome. Nature Genetics. 1997;16(1):28-36
69 - Guimera J, Casas C, Estivill X, Pritchard M. Human minibrain homologue (MNBH/DYRK1): Characterization, alternative splicing, differential tissue expression, and overexpression in Down syndrome. Genomics. 1999;57(3):407-418
70 - Altafaj X, Dierssen M, Baamonde C, Martí E, Visa J, Guimerà J, et al. Neurodevelopmental delay, motor abnormalities and cognitive deficits in transgenic mice overexpressing Dyrk1A (minibrain), a murine model of Down's syndrome. Human Molecular Genetics. 2001;10(18):1915-1923
71 - Fotaki V, Dierssen M, Alcántara S, Martínez S, Martí E, Casas C, et al. Dyrk1A haploinsufficiency affects viability and causes developmental delay and abnormal brain morphology in mice. Molecular Cell. Biology. 2002;22(18):6636-6647
72 - Laguna A, Aranda S, Barallobre MJ, Barhoum R, Fernández E, Fotaki V, et al. The protein kinase DYRK1A regulates caspase-9-mediated apoptosis during retina development. Developmental Cell. 2008;15(6):841-853. DOI: 10.1016/j.devcel.2008.10.014
73 - Yabut O, Domogauer J, D'Arcangelo G. Dyrk1A overexpression inhibits proliferation and induces premature neuronal differentiation of neural progenitor cells. Journal of Neuroscience. 2010;30(11):4004-4014. DOI: 10.1523/JNEUROSCI.4711-09.2010
74 - Guedj F, Pereira PL, Najas S, Barallobre MJ, Chabert C, Souchet B, et al. DYRK1A: A master regulatory protein controlling brain growth. Neurobiology of Disease. 2012;46(1):190-203. DOI: 10.1016/j.nbd.2012.01.007
75 - Duchon A, Herault Y. DYRK1A, a dosage-sensitive gene involved in neurodevelopmental disorders, is a target for drug development in Down syndrome. Frontiers in Behavioral Neuroscience 2016;10:104. DOI: 10.3389/fnbeh.2016.00104
76 - Park J, Oh Y, Yoo L, Jung MS, Song WJ, Lee SH, et al. Dyrk1A phosphorylates p53 and inhibits proliferation of embryonic neuronal cells. The Journal of Biological Chemistry. 2010;285(41):31895-31906. DOI: 10.1074/jbc.M110.147520
77 - Hasle H, Clemmensen IH, Mikkelsen M. Risks of leukaemia and solid tumours in individuals with Down's syndrome. Lancet. 2000;355(9199):165-169
78 - Hasle H. Pattern of malignant disorders in individuals with Down's syndrome. The Lancet Oncology. 2001l;2(7):429-436
79 - Nižetić D, Groet J. Tumorigenesis in Down's syndrome: Big lessons from a small chromosome. Nature Reviews Cancer. 2012;12(10):721-732. DOI: 10.1038/nrc3355
80 - Mancini M, Toker A. NFAT proteins: Emerging roles in cancer progression. Nature Reviews Cancer. 2009;9(11):810-820. DOI: 10.1038/nrc2735
81 - Müller MR, Rao A. NFAT, immunity and cancer: A transcription factor comes of age. Nature Reviews Immunology. 2010;10(9):645-656. DOI: 10.1038/nri2818
82 - Shou J, Jing J, Xie J, You L, Jing Z, Yao J, et al. Nuclear factor of activated T cells in cancer development and treatment. Cancer Letters. 2015;361(2):174-184. DOI: 10.1016/j.canlet.2015.03.005
83 - Gwack Y, Sharma S, Nardone J, Tanasa B, Iuga A, Srikanth S, et al. A genome-wide Drosophila RNAi screen identifies DYRK-family kinases as regulators of NFAT. Nature. 2006;441(7093):646-650
84 - Taira N, Nihira K, Yamaguchi T, Miki Y, Yoshida K. DYRK2 is targeted to the nucleus and controls p53 via Ser46 phosphorylation in the apoptotic response to DNA damage. Molecular Cell. 2007;25(5):725-738
85 - Taira N, Yamamoto H, Yamaguchi T, Miki Y, Yoshida K. ATM augments nuclear stabilization of DYRK2 by inhibiting MDM2 in the apoptotic response to DNA damage. The Journal of Biological Chemistry. 2010;285(7):4909-4919. DOI: 10.1074/jbc.M109.042341
86 - Yamamoto T, Nihira NT, Yogosawa S, Aoki K, Takeda H, Sawasaki T, Yoshida K. Interaction between RNF8 and DYRK2 is required for the recruitment of DNA repair molecules to DNA double-strand breaks. FEBS Letters. 2017;591(6):842-853. DOI: 10.1002/1873-3468.12596
87 - Stephens P, Edkins S, Davies H, Greenman C, Cox C, Hunter C, et al. A screen of the complete protein kinase gene family identifies diverse patterns of somatic mutations in human breast cancer. Nature Genetics. 2005;37(6):590-592
88 - Greenman C, Stephens P, Smith R, Dalgliesh GL, Hunter C, Bignell G, et al. Patterns of somatic mutation in human cancer genomes. Nature. 2007;446(7132):153-158
89 - Taira N, Mimoto R, Kurata M, Yamaguchi T, Kitagawa M, Miki Y, Yoshida K. DYRK2 priming phosphorylation of c-Jun and c-Myc modulates cell cycle progression in human cancer cells. Journal of Clinical Investigation. 2012;122(3):859-872. DOI: 10.1172/JCI60818
90 - Mimoto R, Taira N, Takahashi H, Yamaguchi T, Okabe M, Uchida K, et al. DYRK2 controls the epithelial-mesenchymal transition in breast cancer by degrading Snail. Cancer Letters. 2013;339(2):214-225. DOI: 10.1016/j.canlet.2013.06.005
91 - Yamaguchi N, Mimoto R, Yanaihara N, Imawari Y, Hirooka S, Okamoto A, Yoshida K. DYRK2 regulates epithelial-mesenchymal-transition and chemosensitivity through Snail degradation in ovarian serous adenocarcinoma. Tumour Biology. 2015;36(8):5913-5923. DOI: 10.1007/s13277-015-3264-y
92 - Mimoto R, Imawari Y, Hirooka S, Takeyama H, Yoshida K. Impairment of DYRK2 augments stem-like traits by promoting KLF4 expression in breast cancer. Oncogene. 2017;36(13):1862-1872. DOI: 10.1038/onc.2016.349
93 - Sutherland C. What are the bona fide GSK3 substrates? International Journal of Alzheimer's Disease. 2011;2011:505607. DOI: 10.4061/2011/505607
94 - Park JE, Soung NK, Johmura Y, Kang YH, Liao C, Lee KH, et al. Polo-box domain: A versatile mediator of polo-like kinase function. Cellular and Molecular Life Sciences. 2010;67(12):1957-1970. DOI: 10.1007/s00018-010-0279-9
95 - Yuan K, Huang Y, Yao X. Illumination of mitotic orchestra during cell division: A Polo view. Cellular Signalling. 2011;23(1):1-5. DOI:10.1016/j.cellsig.2010.07.003
96 - Meggio F, Pinna LA. One-thousand-and-one substrates of protein kinase CK2? FASEB Journal. 2003;17(3):349-368
97 - St-Denis N, Gabriel M, Turowec JP, Gloor GB, Li SS, Gingras AC, Litchfield DW. Systematic investigation of hierarchical phosphorylation by protein kinase CK2. Journal of Proteomics. 2015;118:49-62. DOI: 10.1016/j.jprot.2014.10.020
98 - Embi N, Rylatt DB, Cohen P. Glycogen synthase kinase-3 from rabbit skeletal muscle. Separation from cyclic-AMP-dependent protein kinase and phosphorylase kinase. European Journal of Biochemistry. 1980;107(2):519-527
99 - Woodgett JR. Molecular cloning and expression of glycogen synthase kinase-3/factor A. The EMBO Journal. 1990;9(8):2431-2438
100 - Thomas GM, Frame S, Goedert M, Nathke I, Polakis P, Cohen P. A GSK3-binding peptide from FRAT1 selectively inhibits the GSK3-catalysed phosphorylation of axin and beta-catenin. FEBS Letters. 1999;458(2):247-251
101 - Kim NG, Xu C, Gumbiner BM. Identification of targets of the Wnt pathway destruction complex in addition to beta-catenin. Proceedings of the National Academy of Sciences of the United States of America. 2009;106(13):5165-5170. DOI: 10.1073/pnas.0810185106
102 - Xu C, Kim NG, Gumbiner BM. Regulation of protein stability by GSK3 mediated phosphorylation. Cell Cycle. 2009;8(24):4032-4039
103 - Wodarz A, Nusse R. Mechanisms of Wnt signaling in development. Annual Review of Cell and Developmental Biology 1998;14:59-88
104 - Clevers H, Nusse R. Wnt/β-catenin signaling and disease. Cell. 2012;149(6):1192-1205. DOI: 10.1016/j.cell.2012.05.012
105 - Schuijers J, Clevers H. Adult mammalian stem cells: The role of Wnt, Lgr5 and R-spondins. The EMBO Journal. 2012;31(12):2685-2696. DOI: 10.1038/emboj.2012.149
106 - Polakis P. The many ways of Wnt in cancer. Current Opinion in Genetics and Development. 2007;17(1):45-51
107 - Kandoth C, McLellan MD, Vandin F, Ye K, Niu B, Lu C, et al. Mutational landscape and significance across 12 major cancer types. Nature. 2013;502(7471):333-339. DOI: 10.1038/nature12634
108 - Zhan T, Rindtorff N, Boutros M. Wnt signaling in cancer. Oncogene. 2017;36(11):1461-1473. DOI: 10.1038/onc.2016.304
109 - Duchartre Y, Kim YM, Kahn M. The Wnt signaling pathway in cancer. Critical Reviews in Oncology/Hematology 2016;99:141-149. DOI: 10.1016/j.critrevonc.2015.12.005
110 - Rubinfeld B, Albert I, Porfiri E, Fiol C, Munemitsu S, Polakis P. Binding of GSK3beta to the APC-beta-catenin complex and regulation of complex assembly. Science. 1996;272(5264):1023-1026
111 - Ikeda S, Kishida S, Yamamoto H, Murai H, Koyama S, Kikuchi A. Axin, a negative regulator of the Wnt signaling pathway, forms a complex with GSK-3beta and beta-catenin and promotes GSK-3beta-dependent phosphorylation of beta-catenin. The EMBO Journal. 1998;17(5):1371-1384
112 - Nakamura T, Hamada F, Ishidate T, Anai K, Kawahara K, Toyoshima K, Akiyama T. Axin, an inhibitor of the Wnt signalling pathway, interacts with beta-catenin, GSK-3beta and APC and reduces the beta-catenin level. Genes to Cells. 1998;3(6):395-403
113 - Li VS, Ng SS, Boersema PJ, Low TY, Karthaus WR, Gerlach JP, et al. Wnt signaling through inhibition of β-catenin degradation in an intact Axin1 complex. Cell. 2012;149(6):1245-1256. DOI: 10.1016/j.cell.2012.05.002
114 - Schwarz-Romond T, Asbrand C, Bakkers J, Kühl M, Schaeffer HJ, Huelsken J, et al. The ankyrin repeat protein Diversin recruits Casein kinase Iepsilon to the beta-catenin degradation complex and acts in both canonical Wnt and Wnt/JNK signaling. Genes and Development. 2002;16(16):2073-2084
115 - Ha NC, Tonozuka T, Stamos JL, Choi HJ, Weis WI. Mechanism of phosphorylation-dependent binding of APC to beta-catenin and its role in beta-catenin degradation. Molecular Cell. 2004;15(4):511-521
116 - Xing Y, Clements WK, Le Trong I, Hinds TR, Stenkamp R, Kimelman D, Xu W. Crystal structure of a beta-catenin/APC complex reveals a critical role for APC phosphorylation in APC function. Molecular Cell. 2004;15(4):523-533
117 - Liu J, Xing Y, Hinds TR, Zheng J, Xu W. The third 20 amino acid repeat is the tightest binding site of APC for beta-catenin. Journal of Molecular Biology. 2006;360(1):133-144
118 - Ferrarese A, Marin O, Bustos VH, Venerando A, Antonelli M, Allende JE, Pinna LA. Chemical dissection of the APC Repeat 3 multistep phosphorylation by the concerted action of protein kinases CK1 and GSK3. Biochemistry. 2007;46(42):11902-11910
119 - Amit S, Hatzubai A, Birman Y, Andersen JS, Ben-Shushan E, Mann M, et al. Axin-mediated CKI phosphorylation of beta-catenin at Ser 45: A molecular switch for the Wnt pathway. Genes and Development. 2002;16(9):1066-1076
120 - Liu C, Li Y, Semenov M, Han C, Baeg GH, Tan Y, et al. Control of beta-catenin phosphorylation/degradation by a dual-kinase mechanism. Cell. 2002;108(6):837-847
121 - Hagen T, Vidal-Puig A. Characterisation of the phosphorylation of beta-catenin at the GSK-3 priming site Ser45. Biochemical and Biophysical Research Communications. 2002;294(2):324-328
122 - Marikawa Y, Elinson RP. beta-TrCP is a negative regulator of Wnt/beta-catenin signaling pathway and dorsal axis formation in Xenopus embryos. Mechanisms of Development. 1998;77(1):75-80
123 - Hart M, Concordet JP, Lassot I, Albert I, del los Santos R, Durand H, et al. The F-box protein beta-TrCP associates with phosphorylated beta-catenin and regulates its activity in the cell. Current Biology. 1999;9(4):207-210
124 - Kitagawa M, Hatakeyama S, Shirane M, Matsumoto M, Ishida N, Hattori K, et al. An F-box protein, FWD1, mediates ubiquitin-dependent proteolysis of beta-catenin. The EMBO Journal. 1999;18(9):2401-2410
125 - Su Y, Fu C, Ishikawa S, Stella A, Kojima M, Shitoh K, et al. APC is essential for targeting phosphorylated beta-catenin to the SCFbeta-TrCP ubiquitin ligase. Molecular Cell. 2008;32(5):652-661. DOI: 10.1016/j.molcel.2008.10.023
126 - Elyada E, Pribluda A, Goldstein RE, Morgenstern Y, Brachya G, Cojocaru G, et al. CKIα ablation highlights a critical role for p53 in invasiveness control. Nature. 2011;470(7334):409-413. DOI: 10.1038/nature09673
127 - Lebensohn AM, Dubey R, Neitzel LR, Tacchelly-Benites O, Yang E, Marceau CD, Davis EM, Patel BB, Bahrami-Nejad Z, Travaglini KJ, Ahmed Y, Lee E, Carette JE, Rohatgi R. Comparative genetic screens in human cells reveal new regulatory mechanisms in WNT signaling. Elife. 2016;5(pii):e21459. DOI: 10.7554/eLife.21459
128 - Bhanot P, Brink M, Samos CH, Hsieh JC, Wang Y, Macke JP, et al. A new member of the frizzled family from Drosophila functions as a Wingless receptor. Nature. 1996;382(6588):225-230.
129 - Wehrli M, Dougan ST, Caldwell K, O'Keefe L, Schwartz S, Vaizel-Ohayon D, et al. arrow encodes an LDL-receptor-related protein essential for Wingless signalling. Nature. 2000;407(6803):527-530.
130 - Tamai K, Semenov M, Kato Y, Spokony R, Liu C, Katsuyama Y, et al. LDL-receptor-related proteins in Wnt signal transduction. Nature. 2000;407(6803):530-535
131 - He X, Semenov M, Tamai K, Zeng X. LDL receptor-related proteins 5 and 6 in Wnt/beta-catenin signaling: Arrows point the way. Development. 2004;131(8):1663-1677.
132 - Bilic J, Huang YL, Davidson G, Zimmermann T, Cruciat CM, Bienz M, Niehrs C. Wnt induces LRP6 signalosomes and promotes dishevelled-dependent LRP6 phosphorylation. Science. 2007;316(5831):1619-1622
133 - Mao J, Wang J, Liu B, Pan W, Farr GH 3rd, Flynn C, et al. Low-density lipoprotein receptor-related protein-5 binds to Axin and regulates the canonical Wnt signaling pathway. Molecular Cell. 2001;7(4):801-809
134 - Cliffe A, Hamada F, Bienz M. A role of Dishevelled in relocating Axin to the plasma membrane during wingless signaling. Current Biology. 2003;13(11):960-966
135 - Tamai K, Zeng X, Liu C, Zhang X, Harada Y, Chang Z, He X. A mechanism for Wnt coreceptor activation. Molecular Cell. 2004;13(1):149-156
136 - Davidson G, Wu W, Shen J, Bilic J, Fenger U, Stannek P, et al. Casein kinase 1 gamma couples Wnt receptor activation to cytoplasmic signal transduction. Nature. 2005;438(7069):867-872
137 - Zeng X, Tamai K, Doble B, Li S, Huang H, Habas R, et al. A dual-kinase mechanism for Wnt co-receptor phosphorylation and activation. Nature. 2005;438(7069):873-877
138 - Mi K, Dolan PJ, Johnson GV. The low density lipoprotein receptor-related protein 6 interacts with glycogen synthase kinase 3 and attenuates activity. The Journal of Biological Chemistry. 2006;281(8):4787-4794
139 - Zeng X, Huang H, Tamai K, Zhang X, Harada Y, Yokota C, et al. Initiation of Wnt signaling: Control of Wnt coreceptor Lrp6 phosphorylation/activation via frizzled, dishevelled and axin functions. Development. 2008;135(2):367-375
140 - Cselenyi CS, Jernigan KK, Tahinci E, Thorne CA, Lee LA, Lee E. LRP6 transduces a canonical Wnt signal independently of Axin degradation by inhibiting GSK3's phosphorylation of beta-catenin. Proceedings of the National Academy of Sciences of the United States of America. 2008;105(23):8032-8037. DOI: 10.1073/pnas.0803025105
141 - Piao S, Lee SH, Kim H, Yum S, Stamos JL, Xu Y, et al. Direct inhibition of GSK3beta by the phosphorylated cytoplasmic domain of LRP6 in Wnt/beta-catenin signaling. PLoS One. 2008;3(12):e4046. DOI: 10.1371/journal.pone.0004046
142 - Wu G, Huang H, Garcia Abreu J, He X. Inhibition of GSK3 phosphorylation of beta-catenin via phosphorylated PPPSPXS motifs of Wnt coreceptor LRP6. PLoS One. 2009;4(3):e4926. DOI: 10.1371/journal.pone.0004926
143 - Taelman VF, Dobrowolski R, Plouhinec JL, Fuentealba LC, Vorwald PP, Gumper I, et al. Wnt signaling requires sequestration of glycogen synthase kinase 3 inside multivesicular endosomes. Cell. 2010;143(7):1136-1148. DOI: 10.1016/j.cell.2010.11.034
144 - Lau AW, Fukushima H, Wei W. The Fbw7 and betaTRCP E3 ubiquitin ligases and their roles in tumorigenesis. Frontiers in Bioscience (Landmark edition). 2012;17:2197-2212
145 - Mimoto R, Nihira NT, Hirooka S, Takeyama H, Yoshida K. Diminished DYRK2 sensitizes hormone receptor-positive breast cancer to everolimus by the escape from degrading mTOR. Cancer Letters. 2017;384:27-38. DOI: 10.1016/j.canlet.2016.10.015
146 - Díaz VM, de Herreros AG. F-box proteins: Keeping the epithelial-to-mesenchymal transition (EMT) in check. Seminars in Cancer Biology 2016;36:71-79. DOI: 10.1016/j.semcancer.2015.10.003
147 - Zheng N, Zhou Q, Wang Z, Wei W. Recent advances in SCF ubiquitin ligase complex: Clinical implications. Biochimica et Biophysica Acta. 2016;1866(1):12-22. DOI: 10.1016/j.bbcan.2016.05.001
148 - Davidson G, Shen J, Huang YL, Su Y, Karaulanov E, Bartscherer K, et al. Cell cycle control of wnt receptor activation. Developmental Cell. 2009;17(6):788-799. DOI: 10.1016/j.devcel.2009.11.006
149 - Acebron SP, Karaulanov E, Berger BS, Huang YL, Niehrs C. Mitotic wnt signaling promotes protein stabilization and regulates cell size. Molecular Cell. 2014;54(4):663-674. DOI: 10.1016/j.molcel.2014.04.014