A transcriptomics study of differentiated C2C12 myoblasts identified novel functional responses to 17β-estradiol.

Previous studies of the role of 17β-estradiol (E2) in myoblast differentiation have produced conflicting data. Therefore, this work aimed to determine the role of E2 on myoblast differentiation and specific myofiber formation. Murine C2C12 myoblasts were cultured in proliferation medium or differentiation medium/10 nM E2. The role of E2 on specific myosin heavy chain (MyHC) or estrogen receptor (ER) expression was examined using real-time quantitative RT-PCR (RT-qPCR). Transcriptome studies of E2 on myoblast differentiation were accomplished by microarray analyses. The expression levels of candidate genes from microarrays and four and a half LIM domains 1 (Fhl1) were detected with RT-qPCR. E2 in differentiation medium significantly up-regulated MyHC I expression, but exerted the opposite effects on MyHC II a, MyHC II b, and MyHC II d. Both ER-α and ER-β were decreased in differentiated C2C12, and E2 partially restored ER-β expression. Sixty-two up-regulated and 116 down-regulated genes treated by E2 were identified, and RT-qPCR validation results showed seven cytoskeletal genes (Myh8, Cenpe, Jak3, Obscn, Ldb3, Mybpc2, Col4a3bp), three genes related to ion channels (Kcnq1, Lrrc26, P2rx3) and Fhl1 transcript 2 were associated with the effects of E2 on myoblast differentiation. These findings suggested E2 helped slow type MyH I fiber formation and impeded fast 2A, 2X/D, and 2B fiber formation.