Nerve growth factor increases connexin43 phosphorylation and gap junctional intercellular communication.
The function of gap junctions is regulated by the phosphorylation state of their connexin subunits. Numerous growth factors are known to regulate connexin phosphorylation; however, the effect of nerve growth factor on gap junction function is not understood. The phosphorylation of connexin subunits is a key event during many aspects of the lifecycle of a connexin, including open/close states, assembly/trafficking, and degradation, and thus affects the functionality of the channel. PC12 cells infected with connexin43 (Cx43) retrovirus were used as a neuronal model to characterize the signal transduction pathways activated by nerve growth factor (NGF) that potentially affect the functional state of Cx43. Immunoblot analysis demonstrated that Cx43 and the mitogen-activated protein kinase (MAPK), ERK-1/2, were phosphorylated in response to TrkA activation via NGF and that phosphorylation could be prevented by treatment with the MEK-1/2 inhibitor U0126. The effects of NGF on gap junction intercellular communication were examined by monitoring fluorescence recovery after photobleaching PC12-Cx43 cells preloaded with calcein. Fluorescence recovery in the photobleached area increased after NGF treatment and decreased when pretreated with the MEK-1/2 inhibitor U0126. These data are the first to show a direct signaling link between neurotrophins and the phosphorylation of connexin proteins through the MAPK pathway resulting in increased gap junctional intercellular communication. Neurotrophic regulation of connexin activity provides a novel mechanism of regulating intercellular communication between neurons during nervous system development and repair.
Cushing
Paul
P
Department of Anatomy and Cell Biology, Faculty of Medicine and Dentistry, The University of Western Ontario, London, Canada.
Bhalla
Ruchi
R
Johnson
Andrew M
AM
Rushlow
Walter J
WJ
Meakin
Susan O
SO
Belliveau
Daniel J
DJ
D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002070:Butadienes / Q000494:pharmacology; D002450:Cell Communication / Q000187:drug effects* / Q000502:physiology; D045744:Cell Line, Tumor; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007365:Intercellular Junctions / Q000187:drug effects* / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases; D009154:Mutation; D009414:Nerve Growth Factors / Q000494:pharmacology*; D009447:Neuroblastoma / Q000473:pathology; D009570:Nitriles / Q000494:pharmacology; D016716:PC12 Cells / Q000145:classification; D010766:Phosphorylation / Q000187:drug effects; D038761:Photobleaching / Q000187:drug effects; D051381:Rats; D012190:Retroviridae / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D002070:Butadienes; D018031:Connexin 43; D004791:Enzyme Inhibitors; D009414:Nerve Growth Factors; D009570:Nitriles; C113580:U 0126; D014446:Tyrosine 3-Monooxygenase; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases