Perilipins: A family of five fat-droplet storing proteins that play a significant role in fat homeostasis.

Lipid droplets are organelles with unique spherical structures. They consist of a hydrophobic neutral lipid core that varies depending on the cell type and tissue. These droplets are surrounded by phospholipid monolayers, along with heterogeneous proteins responsible for neutral lipid synthesis and metabolism. Additionally, there are specialized lipid droplet-associated surface proteins. Recent evidence suggests that proteins from the perilipin family (PLIN) are associated with the surface of lipid droplets and are involved in their formation. These proteins have specific roles in hepatic lipid droplet metabolism, such as protecting the lipid droplets from lipase action and maintaining a balance between lipid storage and utilization in specific cells. Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by the accumulation of lipid droplets in more than 5% of the hepatocytes. This accumulation can progress into metabolic dysfunction-associated steatohepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. The accumulation of hepatic lipid droplets in the liver is associated with the progression of MASLD and other diseases such as sarcopenic obesity. Therefore, it is crucial to understand the role of perilipins in this accumulation, as these proteins are key targets for developing novel therapeutic strategies. This comprehensive review aims to summarize the structure and characteristics of PLIN proteins, as well as their pathogenic role in the development of hepatic steatosis and fatty liver diseases.