CD38/cADPR/Ca2+ Pathway Promotes Cell Proliferation and Delays Nerve Growth Factor-induced Differentiation in PC12 Cells

Intracellular Ca2+ mobilization plays an important role in a wide variety of cellular processes, and multiple second messengers are responsible for mediating intracellular Ca2+ changes. Here we explored the role of one endogenous Ca2+-mobilizing nucleotide, cyclic adenosine diphosphoribose (cADPR), in the proliferation and differentiation of neurosecretory PC12 cells. We found that cADPR induced Ca2+ release in PC12 cells and that CD38 is the main ADP-ribosyl cyclase responsible for the acetylcholine (ACh)-induced cADPR production in PC12 cells. In addition, the CD38/cADPR signaling pathway is shown to be required for the ACh-induced Ca2+ increase and cell proliferation. Inhibition of the pathway, on the other hand, accelerated nerve growth factor (NGF)-induced neuronal differentiation in PC12 cells. Conversely, overexpression of CD38 increased cell proliferation but delayed NGF-induced differentiation. Our data indicate that cADPR plays a dichotomic role in regulating proliferation and neuronal differentiation of PC12 cells.