Expression and regulation of phospholipase D during neuronal differentiation of PC12 cells

To assess a possible role for phospholipase D (PLD) in PC12 cell signal tra nsduction and differentiation, we have investigated the expression of PLD i n PC12 cells and found that the differentiation factor, nerve growth factor (NGF) increased PLD1 protein expression and phorbol 12-myristate 13 acetat e (PMA)-induced PLD activity. During neuronal differentiation, this effect showed correlation to the protein expression levels of classical protein ki nase C (PKC) isozymes, PKC-alpha and -beta II, but there was no significant increase in the protein level of RhoA, another regulatory factor for PLD a ctivation. Interestingly, PLD1 was associated with PKC-alpha or beta II, an d its association gradually increased as NGF-induced neuronal differentiati on progressed. PKC inhibitor, Ro-31-8220, caused a significant inhibition o f neurite outgrowth and PLD activity. Furthermore, PLD1 was constitutively associated with the Shc adaptor molecule, the overexpression of which is kn own to induce PLD activity and to induce neurite outgrowth. Taken together, the data in this study suggests that PLD1 is closely implicated in neurona l differentiation of PC12 cells. (C) 2001 Elsevier Science Ltd. All rights reserved.