Nerve growth factor-induced stimulation of p38 mitogen-activated protein kinase in PC12 cells is partially mediated via G(i/o) proteins.
Differentiation of PC12 cells by nerve growth factor (NGF) requires the activation of various mitogen-activated protein kinases (MAPKs) including p38 MAPK. Accumulating evidence has suggested cross-talk regulation of NGF-induced responses by G protein-coupled receptors, thus we examined whether NGF utilizes G(i/o) proteins to regulate p38 MAPK in PC12 cells. Induction of p38 MAPK phosphorylation by NGF occurred in a time- and dose-dependent manner and was partially inhibited by pertussis toxin (PTX). NGF-dependent p38 MAPK phosphorylation became insensitive to PTX treatment upon transient expressions of Galpha(z) or the PTX-resistant mutants of Galpha(i2) and Galpha(oA). Moreover, Galpha(i2) was co-immunoprecipitated with the TrkA receptor from PC12 cell lysates. To discern the participation of various signaling intermediates, PC12 cells were treated with a panel of specific inhibitors prior to the NGF challenge. NGF-induced p38 MAPK phosphorylation was abolished by inhibitors of Src (PP1, PP2, and SU6656) and MEK1/2 (U0126). Inhibition of the p38 MAPK pathway also suppressed NGF-induced PC12 cell differentiation. In contrast, inhibitors of JAK2, phospholipase C, protein kinase C and Ca(2+)/calmodulin-dependent kinase II did not affect the ability of NGF to activate p38 MAPK. Collectively, these studies indicate that NGF-dependent p38 MAPK activity may be mediated via G(i2) protein, Src, and the MEK/ERK cascade.
Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Lisa Y
LY
Yung
Prudence H
PH
Tso
Eddy H T
EH
Wu
Jowie C H
JC
Yu
Nancy Y
NY
Ip
Yung H
YH
Wong
D000818:Animals; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D020932:Nerve Growth Factor / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D016716:PC12 Cells; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D051381:Rats; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D020932:Nerve Growth Factor; D016392:Proto-Oncogene Proteins pp60(c-src); D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go