title: Bombesin, platelet-derived growth factor, and diacylglycerol induce selective membrane association and down-regulation of protein kinase C isotypes in Swiss 3T3 cells.
abstract: Swiss 3T3 cells contain protein kinase C (PKC) isotypes alpha, delta, epsilon and zeta (Olivier, A. R., and Parker, P. J. (1992) J. Cell. Physiol. 152, 240-244). Acute stimulation of quiescent cells with the neuropeptide bombesin decreases the mobility of PKC-delta and PKC-epsilon on SDS-polyacrylamide gels. These slower migrating forms of PKC-delta and PKC-epsilon rapidly (within 1 s) and selectively are found associated with the Triton X-100-soluble membrane fraction. No change in the mobility or distribution of PKC-alpha or PKC-zeta is detected. Long-term treatment of cells with bombesin induces selective membrane association and down-regulation of PKC-delta and PKC-epsilon (decreasing 70 and 65%, respectively). No change in the long-term distribution of PKC-alpha and PKC-zeta was detected. Bombesin did, however, increase PKC-alpha protein levels by 60% compared to control cells. PKC-zeta levels remained unchanged. Both the shift in mobility and down-regulation of PKC-delta and PKC-epsilon were only induced by mitogenic doses of bombesin. The potent mitogen platelet-derived growth factor induced similar effects on the PKC isotypes delta and epsilon. PKC-alpha and PKC-zeta levels were unaffected. Repeated doses of the synthetic diglyceride 1-oleoyl-2-acetyl-sn-glycerol induced PKC-delta and PKC-epsilon down-regulation and stimulated the cells to divide. Again PKC-alpha and PKC-zeta levels were unaffected. These results show a correlation between the membrane association and down-regulation of PKC-delta and PKC-epsilon and the entry of cells into S phase.
authors.affiliation: Protein Phosphorylation Laboratory, Imperial Cancer Research Fund, London, United Kingdom.
authors.forename: A R
authors.initials: AR
authors.lastname: Olivier
authors.forename: P J
authors.initials: PJ
authors.lastname: Parker
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001839:Bombesin / Q000494:pharmacology*; D004075:Diglycerides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011493:Protein Kinase C / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D004075:Diglycerides; D007328:Insulin; D007527:Isoenzymes; D010982:Platelet-Derived Growth Factor; D011994:Recombinant Proteins; C044295:1,2-dioctanoylglycerol; D011493:Protein Kinase C; D001839:Bombesin