Retinoic acid promotes myogenesis in myoblasts by antagonizing transforming growth factor-beta signaling via C/EBPβ

Abstract

BackgroundThe effects of transforming growth factor-beta (TGFβ) are mediated by the transcription factors Smad2 and Smad3. During adult skeletal myogenesis, TGFβ signaling inhibits the differentiation of myoblasts, and this can be reversed by treatment with retinoic acid (RA). In mesenchymal stem cells and preadipocytes, RA treatment can function in a non-classical manner by stimulating the expression of Smad3. Smad3 can bind to and prevent the bzip transcription factor CCAAT/enhancer-binding protein beta (C/EBPβ) from binding DNA response elements in target promoters, thereby affecting cell differentiation. In skeletal muscle, C/EBPβ is highly expressed in satellite cells and myoblasts and is downregulated during differentiation. Persistent expression of C/EBPβ in myoblasts inhibits their differentiation.MethodsUsing both C2C12 myoblasts and primary myoblasts, we examined the regulation of C/EBPβ expression and activity following treatment with TGFβ and RA.ResultsWe demonstrate that treatment with RA upregulates Smad3, but not Smad2 expression in myoblasts, and can partially rescue the block of differentiation induced by TGFβ. RA treatment reduces C/EBPβ occupancy of the Pax7 and Smad2 promoters and decreased their expression. RA also inhibits the TGFβ-mediated phosphorylation of Smad2, which may also contribute to its pro-myogenic activities. TGFβ treatment of C2C12 myoblasts stimulates C/EBPβ expression, which in turn can stimulate Pax7 and Smad2 expression, and inhibits myogenesis. Loss of C/EBPβ expression in myoblasts partially restores differentiation in the presence of TGFβ.ConclusionsTGFβ acts, at least in part, to inhibit myogenesis by upregulating the expression of C/EBPβ, as treatment with RA or loss of C/EBPβ can partially rescue differentiation in TGFβ-treated cells. This work identifies a pro-myogenic role for Smad3, through the inhibition of C/EBPβ’s actions in myoblasts, and reveals mechanisms of crosstalk between RA and TGFβ signaling pathways.Electronic supplementary materialThe online version of this article (doi:10.1186/s13395-015-0032-z) contains supplementary material, which is available to authorized users.

miR‐206 family is important for mitochondrial and muscle function, but not essential for myogenesis in vitro

“…Nevertheless, 531 and 412 genes were differentially expressed in tKO in comparison to control cells in proliferating and differentiating conditions, respectively (Figure 2B). Among 232 genes upregulated during differentiation in the tKO cells are several involved in retinoic acid regulation (from the top 10: Aldh1a1 , Aldh1a7 , Brinp3 , and Tceal5 ), which was previously described as important factor for myogenesis 70‐72 . Aldehyde dehydrogenases ( Aldh ) are also known to have promyogenic potential 73‐75 …”

miR-206 family is important for mitochondrial and muscle function, but not essential for myogenesis in vitro

“…Nevertheless, 531 and 412 genes were differentially expressed in tKO in comparison to control cells in proliferating and differentiating conditions, respectively (Figure 2B). Among 232 genes upregulated during differentiation in the tKO cells are several involved in retinoic acid regulation (from the top 10: Aldh1a1 , Aldh1a7 , Brinp3 and Tceal5 ), which was previously described as important factor for myogenesis (El Haddad et al, 2017; Halevy and Lerman, 1993; Lamarche et al, 2015). Aldehyde dehydrogenases ( Aldh ) are also known to have promyogenic potential (Jean et al, 2011; Vauchez et al, 2009; Vella et al, 2011).…”

Effects of transforming growth factor‐β1 treatment on muscle regeneration and adipogenesis in glycerol‐injured muscle

“…; Lamarche et al . ). Inhibition of MyoD and myogenin mRNA expression indicates impairment of satellite cell proliferation and differentiation (Zhang et al .…”