Overexpression Of PGC-1α In Human Primary Myotubes Increases Regulators Of Exosome Biogenesis And Secretion

Abstract

Skeletal muscle functions as an endocrine organ. Exosomes, small vesicles containing mRNAs, miRNAs, and proteins, are secreted from muscle cells and facilitate cell-to-cell communication. Our recent work found greater exosome release from oxidative compared to glycolytic muscle. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is a key driver of mitochondrial biogenesis, a characteristic of oxidative muscle. It was hypothesized that PGC-1α regulates exosome biogenesis and secretion in skeletal muscle. PURPOSE: To determine if PGC-1α regulates skeletal muscle exosome biogenesis and secretion. METHODS: On day 4 of differentiation, primary myotubes from vastus lateralis biopsies from lean donors (BMI < 25.0 kg/m2) were exposed to adenovirus encoding human PGC-1α or GFP control. On day 6 of differentiation, culture media was replaced with exosome-free media. On day 8, cells were collected for mRNA and protein analysis. RESULTS: Overexpression of PGC-1α increases regulators of exosome biogenesis in the endosomal sorting complexes required for transport (ESCRT) pathway: Alix (GFP: 2.9 ± 1.0 vs. PGC-1α: 7.6 ± 1.4), TSG-101 (GFP: 1.8 ± 0.1 vs. PGC-1α: 7.3 ± 2.1), CD63 (GFP: 2.6 ± 0.3 vs. PGC-1α: 3.7 ± 0.4), Clathrin (GFP: 3.5 ± 0.1 vs. PGC-1α: 11.6 ± 2.5), and the secretion pathway: Rab27b (GFP: 2.6 ± 0.7; PGC-1α: 3.2 ± 0.3). CONCLUSION: Overexpression of PGC-1α increases gene expression of regulators of exosome biogenesis and secretion in human primary myotubes.