Interconversion of GRP78/BiP. A novel event in the action of Pasteurella multocida toxin, bombesin, and platelet-derived growth factor

• Published in: The Journal of biological chemistry Vol. 267; no. 35; pp. 25239 - 25245
• Main Authors: STADDON, J. M, BOUZYK, M. M, ROZENGURT, E
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 15.12.1992
• Subjects: 3T3 Cells; Adenine - metabolism; Adenosine Diphosphate Ribose - metabolism; Analytical, structural and metabolic biochemistry; Animals; Autoradiography; Bacterial Proteins; Bacterial Toxins - pharmacology; Biological and medical sciences; Bombesin - pharmacology; Carrier Proteins - isolation & purification; Carrier Proteins - metabolism; Cycloheximide - pharmacology; Deuterium; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; Heat-Shock Proteins - metabolism; Kinetics; Methionine - metabolism; Mice; Miscellaneous; Molecular Chaperones; Molecular Weight; Pasteurella; Platelet-Derived Growth Factor - pharmacology; Proteins; Sulfur Radioisotopes; Time Factors; Toxin; Regulation(control); ADP ribosylation; Bombesin; Activation; Platelet derived growth factor; Conformation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)74031-9

Incubation of Swiss 3T3 cells with [2-3H]adenine, as in other cell types, reveals the ADP-ribosylation of GRP78 (the 78-kDa glucose-regulated protein, also known as BiP, the immunoglobulin heavy chain-binding protein), a resident endoplasmic reticulum protein that assists in the processing of proteins destined for secretion or cell surface expression. Here we show that Pasteurella multocida toxin, a potent growth factor for cultured fibroblasts, decreased the ADP-ribosylation of GRP78/BiP to 16 +/- 6% of the control value (n = 23). The action of the toxin occurred after a lag period, was blocked by lysosomotrophic agents, and potentiated by increased incubation time (ED50 4 ng/ml and 1 ng/ml in 4 and 8 h, respectively), thus indicating that the toxin enters the cells to act. Bombesin and platelet-derived growth factor (PDGF) similarly decreased the ADP-ribosylation of GRP78/BiP (ED50 0.5 nM and 2.5 ng/ml, respectively) but acted more rapidly than the toxin. Signaling pathways activated by the toxin, bombesin, and PDGF had effects on the ADP-ribosylation of GRP78/BiP. Thus, activation of protein kinase C alone by phorbol 12,13-dibutyrate was partially effective, and down-regulation of protein kinase C attenuated but did not block the action of the toxin, bombesin, and PDGF. Agents that mobilize Ca2+ from the endoplasmic reticulum (A23187, ionomycin, and thapsigargin) caused a decrease in the ADP-ribosylation of GRP78/BiP that was similar in magnitude to that achieved by the toxin, bombesin, and PDGF, implicating a role for inositol 1,4,5-trisphosphate-mediated Ca2+ mobilization in the action of the mitogenic agents. The growth factor-induced decrease in the ADP-ribosylation of GRP78/BiP may represent its conversion from an inactive to an active state.