Pertussis toxin-sensitive Gi/o proteins are involved in nerve growth factor-induced pro-survival Akt signaling cascade in PC12 cells.
In Galpha(z)-deficient mice, survival of sympathetic neurons is significantly attenuated in the presence of pertussis toxin (PTX). This suggests that G(i/o) proteins may have distinct roles in neuronal survival. Here, we investigated the possible involvement of G(i/o) proteins in nerve growth factor (NGF)-induced pro-survival phosphatidylinositol-3-kinase (PI3K)/Akt signaling in rat pheochromocytoma PC12 cells. Treatment of PC12 cells with NGF increased the Akt phosphorylation level in a time- and dose-dependent manner. The NGF-dependent Akt activation was partially attenuated by PTX or overexpression of regulators of G protein signaling Z1 (RGSZ1) and Galpha-interacting protein (GAIP)), indicating the participation of G(i/o) proteins. In contrast, epidermal growth factor (EGF)-mediated Akt phosphorylation was unaffected by PTX or RGSZ1 and GAIP. Expression of PTX-resistant mutants of Galpha(i1), Galpha(i3), Galpha(oA), and Galpha(oB), but not Galpha(i2), abolished the inhibitory effect of PTX on NGF-induced Akt activation. The use of transducin as a Gbetagamma scavenger further revealed that Gbetagamma subunits rather than Galpha(i/o) acted as the signal transducer. The activation profiles of Akt-regulated downstream effectors such as Bad, IKK, and nuclear factor-kappaB (NFkappaB) were also examined. NGF-stimulated phosphorylation of Bad and IKK and transcriptional activity of NFkappaB were indeed sensitive to treatments with PTX. This is the first study that demonstrates the involvement of G(i/o) proteins in NGF-induced Akt signaling.
Wu
Eddy H T
EH
Department of Biochemistry, the Molecular Neuroscience Center, and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Wong
Yung H
YH
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002470:Cell Survival; D018076:DNA, Complementary / Q000235:genetics; D004815:Epidermal Growth Factor / Q000494:pharmacology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000235:genetics / Q000502:physiology*; D044387:GTP-Binding Protein beta Subunits / Q000502:physiology; D044388:GTP-Binding Protein gamma Subunits / Q000502:physiology; D051550:I-kappa B Kinase; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D020932:Nerve Growth Factor / Q000502:physiology*; D016716:PC12 Cells; D037342:Pertussis Toxin / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D015398:Signal Transduction; D051025:bcl-Associated Death Protein
D002352:Carrier Proteins; D018076:DNA, Complementary; D004815:Epidermal Growth Factor; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D051550:I-kappa B Kinase; D016328:NF-kappa B; D020932:Nerve Growth Factor; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D051025:bcl-Associated Death Protein; C494821:Bad protein, rat; C494920:Akt1 protein, rat