A novel antibiotic tautomycin induced many blebs on the surface of K562 human chronic myeloid leukemia cells, similar to the morphological changes induced by phorbol esters. However, tautomycin did not induce nitroblue tetrazolium reducing activity, when HL60 human promyelocytic leukemia cells were caused to differentiate by quinomycin into mature granulocytes. It did not induce spread of HL60 ...

SUMMARY Tetradecanoyl-phorbol-acetate (TPA) was observed to produce a 15% decrease in the electrophoretic mobility of hyperdiploid Ehrlich-Lettré ascites tumor cells (ELD). This reduction in mobility of ELD was capable of being reversed by washing the cells in Ca2@-free Krebs-Ringer phosphate. An inactive phorbol stereoisomer (4a-phorbol-didecanoate) did not reduce the mobility of ELD. Effects...

Esters of phorbol, a family of tumor-promoting agents, interact in vitro with cellular membranes. In CsCl equi librium density gradients, isotopically labeled phorbol didecanoate cosediments with microsomal and nuclear membranes prepared from rat liver. The interaction be tween these membranes and the promoting compound is enhanced in the presence of native or denatured DNA. Moreover, changes i...

Spinal cord slice preparation and intracellular recording techniques were used to examine the effects of phorbol esters on the sodium- and calcium-dependent action potentials, the excitatory synaptic transmission, the basal (resting) and the dorsal root stimulation-evoked release of 9 endogenous amino acids, including glutamate and aspartate, and the responsiveness of the rat dorsal horn neuron...

Bryostatin 1, a macrocyclic lactone, functions like the phorbol esters biochemically in binding to and activating protein kinase C. Biologically, however, although it induces some phorbol ester responses such as mitogenesis in Swiss 3T3 cells, it paradoxically blocks the effects of the phorbol esters on differentiation in HL-60 promyelocytic leukemia cells and Friend erythroleukemia cells. Sinc...

Insulin-like growth factor I (IGF I) is an important mitogen for vascular smooth muscle cells. To characterize regulation of vascular IGF I receptors, we performed radioligand displacement experiments using rat aortic smooth muscle cells (RASMs). Serum deprivation for 48 hours caused a 401% decrease in IGF I receptor number. Exposure of quiescent RASMs to platelet-derived growth factor (PDGF), ...

The regulation and function of chimaerins, a family of "non-protein kinase C" (PKC) phorbol ester/diacylglycerol receptors with Rac-GAP activity, is largely unknown. In a search for chimaerin-interacting proteins, we isolated Tmp21-I (p23), a protein localized at the perinuclear Golgi area. Remarkably, phorbol esters translocate beta2-chimaerin to the perinuclear region and promote its associat...

Bryostatin 1, a macrocyclic lactone, functions like the phorbol esters biochemically in binding to and activating protein kinase C. Biologically, however, although it induces some phorbol ester responses such as mitogenesis in Swiss 3T3 cells, it paradoxically blocks the effects of the phorbol esters on differentiation in 111-60 promyelocytic leukemia cells and Friend erythroleukemia cells. Sin...

Addition of biologically active phorbol esters to intact quiescent 3T3 mouse cells stimulates an extremely rapid (detectable within seconds) phosphorylation of a Mr 80,000 cellular protein (termed "80k"). Phorbol 12,13-dibutyrate enhances 80k phosphorylation in a dose-dependent manner; half-maximal effect is obtained at 32 nM. The possibility that this phosphorylation is related to the activati...