Early events elicited by Bombesin and structurally related peptides in quiescent Swiss 3T3 cells. I. Activation of protein kinase C and inhibition of epidermal growth factor binding

Journal Article · Wed Jan 01 00:00:00 EST 1986 · J. Cell Biol.; (United States)

DOI:https://doi.org/10.1083/jcb.102.6.2211· OSTI ID:5669743

Zachary, I; Sinnett-Smith, J W; Rozengurt, E

Addition of bombesin to quiescent cultures of Swiss 3T3 cells caused a rapid increase in the phosphorylation of an M/sub r/ 80,000 cellular protein (designated 80k). The effect was both concentration and time dependent. The 80k phosphoproteins generated in response to bombesin and to phorbol 12,13-dibutyrate were identical as judged by one- and two-dimensional PAGE and by peptide mapping after partial proteolysis with Staphylococcus aureus V8 protease. In addition, prolonged pretreatment of 3T3 cells with phorbol 12,13-dibutyrate, which leads to the disappearance of protein kinase C activity, blocked the ability of bombesin to stimulate 80k. Bombesin also caused a rapid (1 min) inhibition of /sup 125/I-labeled epidermal growth factor (/sup 125/I-EGF) binding to Swiss 3T3 cells. The inhibition was both concentration and temperature dependent and resulted from a marked decrease in the affinity of the EGF receptor for its ligand. These results strongly suggest that these responses are mediated by specific high-affinity receptors that recognize the peptides of the bombesin family in Swiss 3T3 cells. While an increase in cytosolic Ca/sup 2 +/ concentration does not mediate the bombesin inhibition of /sup 125/I-EGF binding, the activation of protein kinase C in intact Swiss 3T3 cells by peptides of the bombesin family may lead to rapid inhibition of the binding of /sup 125/I-EGF to its cellular receptor.

• Research Organization: Imperial Cancer Research Fund, London, England
• OSTI ID: 5669743
• Journal Information: J. Cell Biol.; (United States), Vol. 102
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
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