Abstract 13114: Micro RNA206 Secreted From Growing Skeletal Muscle Promotes Angiogenic Response in Endothelial Cells

Introduction: In addition to aerobic exercise, it has been recognized that resistance exercise has beneficial effects for the patients with peripheral arterial disease. Recently, muscle-derived exosomes are demonstrated to convey many types of signaling molecules including microRNAs (miRNAs). Hypothesis: We assessed the hypothesis that exosomal miRNA secreted by growing muscle promotes angiogenic response in endothelial cells. Methods: We utilized skeletal muscle-specific inducible Akt1 transgenic (Akt1-TG) mice that can induce growth of skeletal muscles without exercise training. Exosomes was purified combined usage of ultracentrifugation, and miRNAs were extracted from purified exosomes by spin column-based method. Real-time PCR array and droplet digital PCR was performed to evaluate exosomal miRNA expression. Results: Akt1-TG mice showed remarkable skeletal muscle growth 2 weeks after gene activation (weight of gastrocnemius muscle: 0.21±0.03 vs 0.16±0.02, g, p<0.01). The amount of exosomal proteins did not different between Akt1-TG mice and WT mice (977.7±11.3 vs 826.0±45.2, μg/mL serum, p=0.07). KEGG pathway frequency analysis for 4665 target genes identified by real-time PCR array of miRNAs revealed a significant increase in Akt and its downstream signaling pathways. Among upregulated miRNAs, droplet digital PCR identified that miR-1, -133 and -206 expression was significantly upregulated in Akt1 TG mice compared with WT mice in serum. miR206 was increased in IGF-1-stimulated myotubes. PKH26-labeled exosomes were taken up by human umbilical vein endothelial cells. Exogenous supplementation of exosomal miRNA206 promoted angiogenesis as revealed by spheroid assay, and increased expression of HIF-1 and VEGF in endometrial cells. Conclusions: Exosomal miR206 was upregulated in blood stream in Akt1-TG mice and IGF-stimulated cultured myotubes. Exogenous supplementation of miR206 promoted angiogenic response in endothelial cells. Our data suggest that miR206 secreted from growing muscle act on endothelial cells and promote angiogenesis.