MicroRNA regulation of myogenic satellite cell proliferation and differentiation.

Abstract

Myogenic satellite cells are stem cells responsible for muscle growth and regeneration. MicroRNAs (miRNAs) play significant roles in regulating numerous cellular processes. Two genes essential to satellite cell function are syndecan-4 and glypican-1. To determine if miRNAs influence myogenic satellite cell function, one miRNA predicted to bind syndecan-4 (miR-128) and two predicted to bind glypican-1 (miR-24 and miR-16) were inhibited in vitro by transfection of inhibitors targeting each miRNA. Inhibition of these miRNAs differentially affected the expression of syndecan-4, glypican-1, and myogenic regulatory factors myoD and myogenin. Inhibition of miR-16 reduced proliferation of satellite cells at 72h. Inhibition of miR-128 and miR-24 did not affect proliferation. Inhibition of miRNAs reduced differentiation of satellite cells into myotubes at 48 and 72h except for miR-16, which only affected differentiation at 72h. Inhibition of all three miRNAs decreased myotube width at 24h of differentiation and increased myotube width at 48h of differentiation. Inhibiting these miRNAs also increased the number of nuclei per myotube at 72h of differentiation. These data demonstrate individual miRNAs regulate genes essential for myogenic satellite cell proliferation and differentiation.