Binding of phorbol esters to high-affinity sites on murine fibroblastic cells elicits a mitogenic response.
The level of occupancy of a single class of high-affinity (3H)-phorbol 12, 13-dibutyrate (PDBu) binding sites (Kd = 26 nM) in quiescent Swiss 3T3 cells was correlated with the dose of PDBu required to stimulate rapid (increase in 86Rb uptake, decrease in epidermal growth factor receptor affinity) and long-term (induction of 2-deoxyglucose uptake, initiation of DNA synthesis) events of the proliferative response. Further, structural analogues of PDBu showed identical relative potencies in the inhibition of (3H)-PDBu binding and stimulation of DNA synthesis. Finally, prolonged (24-hour) incubation of Swiss 3T3 or whole mouse embryo fibroblasts with 400 nM PDBu led to a decrease in the number of (3H)-PDBu binding sites (down-regulation) with a parallel loss of rapid and long-term responses of the cells to PDBu (desensitization). These findings indicate that the high-affinity (3H)-PDBu binding sites mediate the mitogenic effects of phorbol esters in fibroblastic cells.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D029742:Caenorhabditis elegans Proteins; D002273:Carcinogens / Q000378:metabolism*; D002352:Carrier Proteins; D002478:Cells, Cultured; D004261:DNA Replication / Q000187:drug effects; D003847:Deoxyglucose / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors; D005347:Fibroblasts / Q000187:drug effects; D007700:Kinetics; D051379:Mice; D008934:Mitogens; D010703:Phorbol Esters / Q000378:metabolism* / Q000494:pharmacology; D010704:Phorbols / Q000378:metabolism*; D011493:Protein Kinase C; D011956:Receptors, Cell Surface / Q000378:metabolism; D011955:Receptors, Drug / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; D002273:Carcinogens; D002352:Carrier Proteins; D008934:Mitogens; D010703:Phorbol Esters; D010704:Phorbols; D011956:Receptors, Cell Surface; D011955:Receptors, Drug; C083141:phorbol ester binding protein; C027776:phorbol ester receptor; C008875:phorbol-12,13-dibenzoate; D004815:Epidermal Growth Factor; D003847:Deoxyglucose; D066246:ErbB Receptors; D011493:Protein Kinase C