T.P.41 The role of the transcriptional factor Pax3 on myogenesis and the effect on the expression of myogenic regulatory factors

Abstract Pax3 is a member of paired box (Pax) family and considered to play an important role in the initial stage of skeletal muscle development. However, its precise function of myogenesis in vitro and in vivo remains unknown. For example, how Pax3 affect the expression of myogenic regulatory factors (MRFs) has not yet been clarified. We have investigated the effect of TSA, one of most potent HDACIs, on myogenesis using the C2C12 skeletal muscle cell line. We found that the change of the expression of Pax3 was not directly correlated with other MRFs (Hagiwara et al., BBRC (2011)). To investigate the role of the transcriptional factor Pax3 on myogenesis and its effect on the expression of MRFs, we performed Pax3 cDNA transfection to the C2C12 cell line by using Effectene© Transfection Reagent (QIAGEN). We analyzed the effect of Pax3 transfection by immunostaining, Western blot, and microarray analyses. In Pax3 transfected C2C12 cells, the formation of myotube is decreased compared to non-transfected cells. At 48 h after Pax3 transfection, the expression MyoD was reduced by Western blot analysis. By microarray analysis, the expression MyoD was reduced and the expression of the cell cycling regulators were changed most significantly. These results suggest that Pax3 inhibit muscle differentiation by suppressing the expression of MyoD and enhancing the expression of the cell cycling regulators. Pax3 may have a role to preserve muscle cell precursors undifferentiated.