Differential mRNA expression and subcellular locations of PI3-kinase isoforms in sympathetic and sensory neurons

Phosphatidylinositol 3-kinase (PI3-kinase) enzymes are key signalling molec ules in the PC12 and neuronal cell survival pathway and are also involved i n the regulation of retrograde axonal transport of nerve growth factor (NGF ), with sympathetic neurons more sensitive to the effects of wortmannin/LY2 94002 than sensory neurons (Bartlett et al, [1997]; Brain Res. 761:257-262; Reynolds et al, [1998] Brain Res. 798:67-74), In this article, we characte rized the mRNA expression of PI3-kinase isoforms in mouse sympathetic super ior cervical ganglia (SCG) and sensory trigeminal ganglia (TGG) and examine d the subcellular locations of immunoreactivity of the PI3-kinase isoforms in mouse cultured SCG and dorsal root ganglion (DRG) neurons. Both the SCG and the TGG express mRNA for the p110 alpha, beta, gamma, delta, and vps34p PI3-kinase isoforms, but the TGG and not the SCG express mRNA for the p170 PI3-kinase isoform, In cultured SCG and DRG neurons, p110 alpha, beta, and gamma immunoreactivity is in the SCG and DRG growth cones, and predominant ly in puncta throughout the growth cone varicosity. However, in the cell bo dies immunoreactivity varied, p110 alpha is localized predominantly at the plasma membrane, while p110 beta and gamma is localized in the perinuclear region of the cells. In addition, unlike other cell types, wortmannin has l ittle effect on actin filament polymerization in either mouse cultured SCG or DRG neurons, J, Neurosci, Res. 56:44-53, 1999, (C) 1999 Wiley-Liss, Inc.