The effects of bombesin on polyphosphoinositide and calcium metabolism in Swiss 3T3 cells.
Bombesin, a peptide mitogen for a variety of cell types, acts as a typical Ca2+-mobilizing hormone in Swiss 3T3 fibroblasts. At its mitogenic concentrations (1-25 nM), bombesin stimulates polyphosphoinositide turnover, i.e. breakdown of phosphatidylinositol 4,5-bisphosphate and a concomitant increase in inositol phosphates in a time- and dose-dependent manner. In particular, bombesin induces an initial transient increase in inositol 1,4,5-trisphosphate concentration, followed by an increase in the concentration of inositol 1,3,4-trisphosphate. Also, within 30 s of bombesin addition, the mass of 1,2-diacylglycerol nearly doubles and remains at this level for up to 60 min. Intracellular [Ca2+] measurements with a photoprotein, aequorin, demonstrate that bombesin stimulates a transient rise in cytosolic free Ca2+ concentration. A mobilization of Ca2+ from an intracellular pool is observed as a dose-dependent, transient increase in 45Ca2+ efflux from prelabeled cells, both in the presence and absence of extracellular Ca2+. Bombesin also induces a sustained increase in Ca2+ influx rate and stimulates 3-O-methyl-D-glucose transport across the plasma membrane. These composite results indicate that the mitogenic effect of bombesin is mediated through an activation of the Ca2+ messenger system.
D019325:3-O-Methylglucose; D000818:Animals; D001839:Bombesin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D004075:Diglycerides / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000378:metabolism; D007700:Kinetics; D008757:Methylglucosides / Q000378:metabolism; D051379:Mice; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000378:metabolism*
C011439:1,2-diacylglycerol; D004075:Diglycerides; D007295:Inositol Phosphates; D008757:Methylglucosides; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D019325:3-O-Methylglucose; D015544:Inositol 1,4,5-Trisphosphate; D001839:Bombesin; D002118:Calcium