A role for PKC epsilon during C2C12 myogenic differentiation

作者：Gaboardi Gian Carlo; Ramazzotti Giulia; Bavelloni Alberto; Piazzi Manuela; Fiume Roberta; Billi Anna Maria; Matteucci Alessandro; Faenza Irene; Cocco Lucio^*

来源：Cellular Signalling, 2010, 22(4): 629-635.

DOI：10.1016/j.cellsig.2009.11.017

• Myogenic differentiation
• Insulin
• PKC epsilon
• PLC gamma 1 signalling

In a previous report we have demonstrated that PLC gamma 1 is involved in the differentiation process of C2C12 myoblasts, induced by insulin administration. In order to identify the downstream targets of PLC gamma 1-dependent signalling, we have analyzed the expression of DAG-dependent PKC isoforms during muscle differentiation. We show that during myotube formation, there is a marked increase of PKC epsilon and eta expression, and that PKC epsilon is able to form a complex with PLC gamma 1. The increase in PKC epsilon amount during myogenic differentiation is associated to an increase in PKC epsilon activity as well. Immunofluorescence analysis indicated that in growing C2C12 cells both PLC gamma 1 and PKC epsilon localize in the cytoplasm with a distinct perinuclear accumulation. In insulin-treated cells, the expression of PLC gamma 1 and PKC epsilon increases and the two proteins are still distributed mainly in the perinuclear region of the myotubes. We show that PLC gamma 1-PKC epsilon complex co-localizes with protein 58 K, a specific Golgi marker. Moreover, our results indicate that the Golgi-associated PKC epsilon form, i.e. PKC epsilon phosphorylated at Set 729, is increased in differentiated myoblasts. Since it has been previously demonstrated that in C2C12 cells after insulin administration cyclin D3 levels could be modulated by PLC gamma 1, we analyzed the effect on cyclin D3 expression of either PKC epsilon overexpression or silencing, in order to investigate whether PKC epsilon could also affect cyclin D3 expression. The results showed that either a modification of PKC epsilon expression or a change in its catalytic activity determines a variation of cyclin D3 levels and muscle differentiation in terms of myogenin expression. These data support a role for PKC epsilon in regulating insulin inositide-dependent PLC gamma 1 signalling in skeletal muscle differentiation.

• 出版日期2010-4