NAFLD is diagnosed, when the liver fat exceeds more than 5% of liver weight. Inside of hepatocytes, these fats are stored in cytosolic lipid droplets. The lipid droplets can be formed from a bud, vesicles of the lipid bilayer, which lines at a vicinity of the endoplasmic reticulum (ER). On the surface of droplets, there are several structural/functional proteins such as lipid droplet proteins, lipogenic enzymes, and lipases. Interestingly, the lipid droplet proteins seem to have great impact on a development of NAFLD. Some proteins can interact with transcriptional factors such as SREBP1c and PPAR-alpha/gamma, and some proteins strongly impact a mitochondrial structure. As a result, the lipid droplet proteins highly influence lipid handling and fatty acid oxidation in hepatocytes. This chapter will elucidate our recent understanding of the role of each lipid droplet protein in fatty liver formation and in hepatic insulin resistance. Existing information on genetically modified animals as well as on human NAFLD was reviewed on Perilipin families, CIDE proteins, Seipin, and PNPLAs. Finally, the chapter will discuss how the lipid droplet proteins could potentially lead/protect from hepatic insulin resistance via abnormal accumulation of ceramides and diacylglycerols, autophagy, ER stress, and oxidative stress.
Part of the book: Non-Alcoholic Fatty Liver Disease