Granulocyte-macrophage colony growth depends on the presence of colony-stimulating activity (CSA). Phorbol esters induce concentration-dependent colony formation in the absence of exogenous CSA. We questioned whether phorbol esters mimicked the action of CSA by directly stimulating colony growth, or whether phorbol esters acted indirectly by inducing marrow cells to release CSA. First, after in...

The PKD (protein kinase D) family are novel DAG (diacylglycerol) receptors. The twin C1 domains of PKD, designated C1a and C1b, have been shown to bind DAG or phorbol esters. However, their ligand-binding activities and selectivities have not been fully characterized. Here, binding activities of isolated C1a, C1b and intact C1a-C1b domains to DAG and phorbol esters were analysed. The isolated C...

Recovery from depletion of the readily releasable pool of vesicles (RRP) in adrenal chromaffin cells was studied at differing basal [Ca2+]i or following protein kinase C (PKC) activation by phorbol esters. Following depletion, the pool size was estimated at varied times from cell capacitance jumps in response to paired depolarizations. The experimentally observed RRP recovery time course and st...

Incubation of human thymocytes in the presence of phorbol esters caused a reversible decrease in the mRNAs encoding terminal deoxynucleotidyltransferase (TdT; EC 2.7.7.31) and adenosine deaminase (ADA; EC 3.5.4.4) and an increase in the mRNA encoding purine nucleoside phosphorylase (PNP; EC 2.4.2.1). The effect of phorbol esters on TdT and ADA mRNA levels can be attributed to an apparent decrea...

Tumor-promoting phorbol esters are potent inflammatory agents for mouse skin, and the potential mechanistic role of inflammation in tumor promotion is under active investigation. We have shown previously that resiniferatoxin, a uniquely irritant phorbol-related diterpene, acts as a capsaicin analogue to induce and then to block neurogenic inflammation. We report here that pretreatment of CD-1 m...

Phorbol esters such as phorbol 12, 13-dibutyrate (PdBu; 40 to 200 nmol/L) or 12-O-tetradecanoyl phorbol 13-acetate (20 to 80 nmol/L) added to aspirinized platelet-rich plasma (PRP) 5 to 15 seconds prior to various platelet stimuli (epinephrine, ADP, prostaglandin endoperoxide analog U44069, collagen, PAF, or vasopressin) potentiate the rate and extent of aggregation and ATP secretion induced by...

A human brain-specific cDNA encoding n-chimaerin, a protein of predicted molecular mass 34 kDa, has sequence identity with two different proteins: protein kinase C (PKC) at the N-terminus and BCR protein [product of the breakpoint-cluster-region (BCR) gene, involved in Philadelphia chromosome translocation] at the C-terminus [Hall, Monfries, Smith, Lim, Kozma, Ahmed, Vannaisungham, Leung & Lim ...

In intact, but not in permeabilized, human erythroid progenitor cells, thrombin and phorbol esters potentiate cellular cAMP formation in response to Gs-coupled receptor agonists such as prostaglandin E1 (PGE1). We show here that the two agonists achieve their phenotypically similar effects by using distinctly different signaling pathways, both of which require protein kinase C (PKC) activation....

Protein kinase C (PKC) modulates the function of the capsaicin receptor transient receptor potential vanilloid 1 (TRPV1). This modulation manifests as increased current when the channel is activated by capsaicin. In addition, studies have suggested that phosphorylation by PKC might directly gate the channel, because PKC-activating phorbol esters induce TRPV1 currents in the absence of applied l...

The seed of Croton tiglium L. (SCT) is a well known folk medicine. In China, it has used to treat gastrointestinal disorders, intestinal inflammation, rheumatism, and so on. Previous studies established its purgative and inflammation properties. In addition, the effects of essential oil of SCT on intestinal transit and gastrointestinal tract has been studied. In the present study, we evaluated ...