Expression of phospholipase C beta family isoenzymes in C2C12 myoblasts during terminal differentiation

In the present work, we have analyzed the expression and subcellular localization of all the members of inositide-specific phospholipase C (PLCbeta) family in muscle differentiation, given that nuclear PLCbeta(1) has been shown to be related to the differentiative process. Cell cultures of C2C12 myoblasts were induced to differentiate towards the phenotype of myotubes, which are also indicated as differentiated C2C12 cells. By means of immunochemical and immunocytochemical analysis, the expression and subcellular localization of PLCbeta(1), beta(2), beta(3), beta(4) have been assessed. As further characterization, we investigated the localization of PLCbeta isoenzymes in C2C12 cells by fusing their cDNA to enhanced green fluorescent protein (GFP). In myoblast culture, PLCbeta(4) was the most expressed isoform in the cytoplasm, whereas PLCbeta(1) and 33 exhibited a lesser expression in this cell compartment. In nuclei of differentiated myotube culture, PLCbeta(1) isoform was expressed at the highest extent. A marked decrease of PLCbeta(4) expression in the cytoplasm of differentiated C2C12 cells was detected as compared to myoblasts. No relevant differences were evidenced as regards the expression of PLCbeta(3) at both cytoplasmatic and nuclear level, whilst PLCbeta(2) expression was almost undetactable. Therefore, we propose that the different subcellular expression of these PLC isoforms, namely the increase Of nuclear PLCbeta(1) and the decrease of cytoplasmatic PLCbeta(4), during the establishment of myotube differentiation, is related to a spatial-temporal signaling event, involved in myogenic differentiation. Once again the subcellular localization appears to be a key step for the diverse signaling activity of PLCbetas. (C) 2004 Wiley-Liss, Inc.