title: A src family tyrosine kinase inhibits neurotransmitter release from neuronal cells.
abstract: Tyrosine kinases are expressed in many tissues, particularly in the central nervous system, and regulate various cellular functions. We report here that a src family tyrosine kinase-specific inhibitor, PP2, enhances neurotransmitter release from PC12 cells and primary cultured neurons. PP2 enhances only Ca(2+)-dependent release; it does not affect basal release. These effects result from an enhancement of vesicular exocytosis and not from the reuptake or refilling of neurotransmitters because Ca(2+)-dependent secretion of an exogenously expressed reporter protein, the human growth hormone (hGH), is also enhanced by PP2. Overexpression of constitutive active v-src, but not of a kinase-inactive mutant, suppressed Ca(2+)-dependent release. In PP2-treated cells, Pyk2, paxillin, and some other proteins showed a decrease in tyrosine phosphorylation, and the enhancement of tyrosine phosphorylation of these proteins in response to Ca(2+) influx was also reduced. Electron and fluorescence microscopy showed that PP2 treatment induced morphological change and decreased phalloidin reactivity at the filopodium-like structures on the processes of PC12 cells. Interestingly, inhibition of actin polymerization with cytochalasin D and latrunculin A enhanced Ca(2+)-dependent, but not basal, release. It is possible that a src family tyrosine kinase, through the regulation of actin dynamics, has an inhibitory function to regulate neurotransmitter release.
authors.affiliation: Mitsubishi Kagaku Institute of Life Sciences, 11 Minamiooya, Machida, Tokyo 194-8511, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ohnishi
authors.forename: S
authors.initials: S
authors.lastname: Yamamori
authors.forename: K
authors.initials: K
authors.lastname: Ono
authors.forename: K
authors.initials: K
authors.lastname: Aoyagi
authors.forename: S
authors.initials: S
authors.lastname: Kondo
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D048429:Cell Size; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D051418:Focal Adhesion Kinase 2; D015870:Gene Expression; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015688:Oncogene Protein pp60(v-src) / Q000235:genetics; D016716:PC12 Cells; D051419:Paxillin; D010590:Phalloidine / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013844:Thiazoles / Q000378:metabolism; D053778:Thiazolidines; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors*
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003598:Cytoskeletal Proteins; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; C496063:Pxn protein, rat; D013844:Thiazoles; D053778:Thiazolidines; D010590:Phalloidine; D018698:Glutamic Acid; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; D015688:Oncogene Protein pp60(v-src); C496054:Ptk2b protein, rat; D019061:src-Family Kinases; C037067:latrunculin A; D002118:Calcium; D004298:Dopamine