Phosphoinositide-specific phospholipase Cβ1 expression is not linked to nerve growth factor-induced differentiation, cell survival or cell cycle control in PC12 rat pheocromocytoma cells

Recent reports have highlighted that phosphoinositicle-specific phospholipase C beta1 expression is linked to neuronal differentiation in different experimental models. We sought to determine whether or not this is also true for nerve growth factor (NGF)-induced neuronal differentiation of rat PC12 cells. However, we did not find differences in the expression of both the forms of phosphoinositicle-specific phospholipase C beta1 (a and b) during sympathetic differentiation of these cells. Also, PC12 cell clones stably overexpressing phosphoinositicle-specific phospholipase CPI were not more susceptible to the differentiating effect of NCF. Furthermore, since it is well established that phosphoinositide-specific phospholipase C beta1 affects cell proliferation, we investigated whether or not PC12 cell clones stably overexpressing phosphoinositicle-specific phospholipase C beta1 showed differences in survival to serum deprivation and cell cycle, when compared to wild type cells. Nevertheless, we did not find any differences in these parameters between wild type cells and the overexpressing clones. Interestingly, in PC12 cells the overexpressed phosphoinositide-specific phospholipase C beta1 did not localize to the nucleus, but by immunofluorescence analysis, was detected in the cytoplasm. Therefore, our findings may represent another important clue to the fact that only when it is located within the nucleus phosphoinositide-specific phospholipase C beta1 is able to influence cell proliferation. (C) 2001 Wiley-Liss, Inc.