STAC3 is required for myotube formation and myogenic differentiation in vertebrate skeletal muscle

ABSTRACT: STAC3 was identified as a nutritionally regulated gene from an Atlantic salmon subtractive hybridization library with highest expression in skeletal muscle. Salmon STAC3 mRNA was highly correlated with myogenin and myoD1a expression during differentiation of a salmon primary myogenic culture and was regulated by amino acid availability. In zebrafish embryos, STAC3 was initially expressed in myotomal adaxial cells and in fast muscle fibres post-segmentation. Morpholino knockdown resulted in defects in myofibrillar protein assembly, particularly in slow muscle fibres, and decreased levels of the hedgehog receptor patched. The function of STAC3 was further characterized in vitro using the mammalian C2C12 myogenic cell line. STAC3 mRNA expression increased during the differentiation of the C2C12 myogenic cell line. Knockdown of STAC3 by RNAi inhibited myotube formation, and microarray analysis revealed that transcripts involved in cell cycle, focal adhesion, cytoskeleton and the pro-myogenic factors IGFBP-5 and IGF2 were down regulated. RNAi-treated cells had suppressed AKT signalling and exogenous IGF2 was unable to rescue the phenotype, however, IGF/AKT signalling was not blocked. Overexpression of STAC3, which results in increased levels of IGFBP-5 mRNA, did not lead to increased differentiation. In synchronized cells, STAC3 mRNA was most abundant during the G1 phase of the cell cycle. RNAi-treated cells were smaller, had higher proliferation rates and decreased proportion of cells in G1 phase when compared to controls, suggesting a role in the G1 phase checkpoint. These results identify STAC3 as a new gene required for myogenic differentiation and myofibrillar protein assembly in vertebrates. We identified STAC3 as being essential for myogenic differentiation. The goal of the microarray analysis was to identify genes that were up- or down-regulated in C2C12 cells when STAC3 expression was inhibited by interfering RNA (RNAi). The microarray compares the C2C12 mouse myogenic cell line between control samples to samples treated with an interfering RNA directed at STAC3. The mouse C2C12 cell line was used at two time points: day 0, which was 24 hours after adding the RNAi, with cells growing in growth media (non-differentiating), and day 1, which was 48 hours after the interfering RNAi was added, and 24 hours after switching to differentiation media.

ORGANISM(S): Mus musculus

PROVIDER: GSE34474 | GEO | 2012/12/01

SECONDARY ACCESSION(S): PRJNA151353

REPOSITORIES: GEO