Nerve Growth Factor Stimulation of p42/p44 Mitogen-Activated Protein Kinase in PC12 Cells: Role of G_i/o, G Protein-Coupled Receptor Kinase 2, β-Arrestin I, and Endocytic Processing

Abstract

In this study, we have shown that nerve growth factor (NGF)-dependent activation of the p42/p44 mitogen-activated protein kinase (p42/p44 MAPK) pathway in PC12 cells can be partially blocked by pertussis toxin (which inactivates the G proteins G(i/o)). This suggests that the Trk A receptor may use a G protein-coupled receptor pathway to signal to p42/p44 MAPK. This was supported by data showing that the NGF-dependent activation of p42/p44 MAPK is potentiated in cells transfected with G protein-coupled receptor kinase 2 (GRK2) or beta-arrestin I. Moreover, GRK2 is constitutively bound with the Trk A receptor, whereas NGF stimulates the pertussis toxin-sensitive binding of beta-arrestin I to the TrkA receptor-GRK2 complex. Both GRK2 and beta-arrestin I are involved in clathrin-mediated endocytic signaling to p42/p44 MAPK. Indeed, inhibitors of clathrin-mediated endocytosis (e.g., monodansylcadaverine, concanavalin A, and hyperosmolar sucrose) reduced the NGF-dependent activation of p42/p44 MAPK. Finally, we have found that the G protein-coupled receptor-dependent component regulating p42/p44 MAPK is required for NGF-induced differentiation of PC12 cells. Thus, NGF-dependent inhibition of DNA synthesis was partially blocked by PD098059 (inhibitor of MAPK kinase-1 activation) and pertussis toxin. Our findings are the first to show that the Trk A receptor uses a classic G protein-coupled receptor-signaling pathway to promote differentiation of PC12 cells.

Regulation of mGlu4 Metabotropic Glutamate Receptor Signaling by Type-2 G-Protein Coupled Receptor Kinase (GRK2)

“…The increased potency of L-AP4 in inhibiting adenylyl cyclase activity in cells overexpressing GRK2 is consistent with this hypothesis. These results are different from those obtained in HEK293 cells expressing the mGlu1 receptor or in PC12 cells, where GRK2 enhances the stimulation of MAPK by quisqualate and NGF, respectively (Iacovelli et al, 2003;Rakhit et al, 2001). This excludes that GRK2 has a nonspecific effect on the MAPK pathway and suggests that the enzyme affects the early steps of mGlu4 receptor signaling.…”

Thrombin induces endothelial cell-surface exposure of the plasminogen receptor annexin 2

“…The observations presented here document the only known trigger for redistribution of A2 and p11 to the HUVEC exterior and provide insight into the mechanism since thrombin induces signaling through G proteins. Like thrombin, the effects of nicotine and nerve growth factor (Rakhit et al, 2001) domains (Sagot et al, 1997); (2) A2 has been identified as a component of caveolae (Stahlhut et al, 2000;Harder and Gerke, 1994;Stan et al, 1997); (3) cell-surface A2 has been colocalized with caveolin (van der Goot, 1997); and (4) nerve growth factor induces exposure of A2 on the neurite surface (Jacovina et al, 2001), we propose that A2 transport to the cell surface may involve G-protein-linked control of caveolae.…”

Induction of Neuritogenesis in PC12 Cells by a Pulsed Electromagnetic Field via MEK-ERK1/2 Signaling

“…Sustained activation of ERK1/2 leads to neurite outgrowth and the development of phenotypic characteristics in PC12 cells (Kao et al, 2001;Rakhit et al, 2001). However, the mechanisms that link the activation of NGF receptors to neuritogenesis are not welldefined.…”