Role Of Plin2 In Lipid Metabolism In Skeletal Muscle

Skeletal muscle is a very important tissue for lipid metabolism. Emerging evidence indicates that increased intramyocellular triacyglycerols (IMTG) have a strong link with insulin resistant and type 2 diabetes mellitus (T2DM). Lipid droplet (LD)-coating proteins may control lipid storage in skeletal muscle. Perilipin 2 (Plin2/adipose differentiation related protein [ADRP]) is one of the most plentiful expressed LD-coating proteins in skeletal muscle. Therefore, it is necessary to investigate how lipid synthesized and used in skeletal muscle and to avoid excessive IMTG accumulation which may induce lipotoxic events and insulin resistant. Here, we used skeletal muscle cell C2C12 as a model to research lipid dynamics and the role of Plin2 in the accumulation of IMTG.First, we found that Plin2 expression was elevated by oleic acid (OA) stimulation in a dose-and time-dependent manner. Mass spectrometry analysis shows that Plin2 was the predominant LD coating protein on LD of C2C12 cells, which was further confirmed by silver staining and Western blot.Next, we knocked out Plin2 in C2C12 cells and found that the ability of Plin2 KO C2C12 cells for triacylglycerol (TAG) synthesis and hydrolysis were both reduced, further research indicated that LDs were markedly larger in size but the numbers were diminished compared with wild type (WT) cells. We isolated LDs from WT and Plin2 knockout cells and observed the LDs morphologies and had proteomics analysis. The average diameter of Plin2 knockout cells’ LD was 843.3 nm while that of the WT was 377.1 nm. Besides, Plin3 became the major LD protein band as Plin2 was absent, and LD-coating proteins has dramatically changed, such as ACSL1 was increased, ATGL DGAT1、DGAT2、Rab18 and ACSL3 were decreased. At the same time, our in vitro experiment showed that Plin2 knockout cells have significantly increased ability to synthesis PC and TAG. Taken together, to maintain lipid dynamic homeostasis, the LD-coating protein Plin2 of the mice skeletal muscle increased both surface area to volume ratio of LD and LD numbers probably to accelerate synthesis and hydrolysis of neutral lipids.