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Journal of Immunology (Baltimore, Md. :... Dec 1991The signals required to induce S phase entry in murine splenic B cells were found to be altered by prolonged treatment with low doses of anti-Ig antibody. Whereas fresh...
The signals required to induce S phase entry in murine splenic B cells were found to be altered by prolonged treatment with low doses of anti-Ig antibody. Whereas fresh splenic B cells are stimulated by the combination of a phorbol ester protein kinase C agonist plus a calcium ionophore, anti-Ig-treated splenic B cells were stimulated by phorbol ester alone, in the absence of a comitogen. The majority of these phorbol ester responsive B cells expressed CD5. The phorbol ester responses of anti-Ig-treated splenic B cells paralleled those previously reported for untreated peritoneal CD5+ B cells in a number of respects: responses were not idiosyncratic to phorbol esters but occurred with nonphorbol protein kinase C agonists; phorbol ester responses were enhanced by IL-4; and, phorbol ester responses occurred rapidly and were greater at 24 than at 48 h. However, the effect of agents that act to raise intracellular levels of cAMP distinguished between anti-Ig-treated splenic B cells and untreated peritoneal B cells in that the phorbol ester responses of the former were enhanced whereas the responses of the latter were inhibited. The present results add a functional dimension to the phenotypic similarity between splenic B cells treated with anti-Ig and resident peritoneal B cells that constitutively express CD5; however, some differences in behavior were noted.
Topics: Animals; Antigens, CD; B-Lymphocytes; CD5 Antigens; Cell Cycle; Cyclic AMP; Dose-Response Relationship, Drug; Dose-Response Relationship, Immunologic; Interleukin-4; Lymphocyte Activation; Mice; Mice, Inbred BALB C; Phorbol Esters; Protein Kinase C; Receptors, Antigen, B-Cell; Time Factors
PubMed: 1719085
DOI: No ID Found -
Proceedings of the National Academy of... Apr 1981The binding of [20-3H]phorbol 12,13-dibutyrate ([3H]PDB) to intact living epidermal cells in monolayer culture was characterized. At 37 degrees C, the maximum specific...
The binding of [20-3H]phorbol 12,13-dibutyrate ([3H]PDB) to intact living epidermal cells in monolayer culture was characterized. At 37 degrees C, the maximum specific [3H]PDB binding (binding displaceable by 30 microM unlabeled PDB) was attained in 15--20 min and was followed by a rapid decrease (down regulation) of radioactivity bound to the cells. The activity lost by the cells during this decrease was found in the incubation medium. Prior exposure of cells to phorbol 12-myristate 13-acetate (PMA; 12-O-tetradecanoylphorbol 13-acetate) but not to phorbol for 2 hr at 37 degrees C caused approximately 55% reduction in the number of measurable binding sites for [3H]PDB. The down regulation was temperature sensitive; there was no loss of radioactivity after 1 hr at 4 degrees C. The specific binding of [3H]PDB at 4 degrees C reached equilibrium in 15--20 min and was saturable and freely reversible. At equilibrium, epidermal cells contained 1.2 x 10(5) binding sites per cell, and binding sites had a KD of 10 nM. Specificity of binding was shown by the observation that the biologically active phorbol esters PMA and 12-deoxyphorbol 13-decanoate inhibited the binding, whereas the inactive parent compound phorbol and the nonphorbol tumor promoter anthralin did not have any effect. The abilities of these compounds to inhibit [3H]PDB binding directly correlates with their tumor promoting activities. Epidermal cells exposed to retinoic acid or fluocinolone acetonide for 24 hr had similar [3H]PDB binding characteristics as untreated cells suggesting that inhibition of tumor promotion induced by these compounds is not mediated through alterations in the phorbol ester binding sites.
Topics: Animals; Animals, Newborn; Binding, Competitive; Caenorhabditis elegans Proteins; Carrier Proteins; Epidermis; Fluocinolone Acetonide; Kinetics; Mice; Phorbol 12,13-Dibutyrate; Phorbol Esters; Phorbols; Protein Kinase C; Receptors, Drug; Tretinoin
PubMed: 6941309
DOI: 10.1073/pnas.78.4.2549 -
Blood Aug 1982Phorbol esters are potent stimulants of the respiratory burst of the human neutrophil as assessed by superoxide (O2-) generation in whole cells and by NADPH-oxidase...
Phorbol esters are potent stimulants of the respiratory burst of the human neutrophil as assessed by superoxide (O2-) generation in whole cells and by NADPH-oxidase activity in a broken-cell 27,000-g particulate fraction. Phorbol 12-myristate, 13-acetate (PMA) and phorbol 12,13-dibutyrate (PDBu) stimulate production of O2- by human neutrophils with ED50 concentrations of 3.9 +/- 2.1 and 41.7 +/- 7.1 nM, respectively. The relation of biologic activity to receptor occupancy was assessed with binding studies of PMA and PDBu. Phorbol ester binding revealed a single high affinity phorbol ester receptor present at 7.6 x 10(5) sites/cell. The binding affinities for PMA and PDBu, 4.9 nM and 38.4 nM, respectively, agreed quantitatively with that of biologic potencies. Because of the high concentration of phorbol ester receptors (up to 125 nM) and the large amount of nonspecific binding at high cell density, apparent discrepancies between ED50's for NADPH-oxidase and whole cell O2- generation were noted. With the use of low cell concentrations, quantitative agreement between intact cell production of O2-, NADPH-oxidase activity, and receptor binding was found. These results further support the identity of the NADPH-oxidase as the enzymatic source of respiratory burst O2- production in human neutrophils.
Topics: Caenorhabditis elegans Proteins; Carrier Proteins; Humans; NADH, NADPH Oxidoreductases; Neuraminidase; Neutrophils; Peroxides; Phorbol 12,13-Dibutyrate; Phorbol Esters; Protein Kinase C; Receptors, Drug
PubMed: 6953983
DOI: No ID Found -
Journal of Neurochemistry Sep 1988The effects of phorbol esters were investigated on the survival of chick sympathetic neurons in a serum-free culture medium. The protein kinase C activator phorbol...
The effects of phorbol esters were investigated on the survival of chick sympathetic neurons in a serum-free culture medium. The protein kinase C activator phorbol 12,13-dibutyrate (PDB) supported about 40% of the plated sympathetic neurons. This number was comparable to that supported by nerve growth factor (NGF). A combination of phorbol ester and NGF did not significantly increase the number of surviving neurons. Phorbol ester-supported sympathetic neurons possessed desipramine-sensitive [3H]-norepinephrine uptake mechanism, and therefore were noradrenegic in character. Two days after the start of cultures, if NGF was replaced by phorbol ester, or phorbol ester was replaced by NGF, the number of surviving sympathetic neurons was essentially the same in both groups, and the uptake of [3H]norepinephrine was also comparable when examined 2 days after the switchover. Interchangeability between phorbol ester and NGF in the survival of sympathetic neurons suggests that both agents act on the same subpopulation of neurons of the chick sympathetic ganglia. The protein kinase C activity of cytosol and particulate fractions of NGF-supported neurons was 0.14 and 0.09 pmol/min/mg protein, respectively. In phorbol ester-supported neurons the activity in the particulate fraction increased by about fivefold. Removal of the phorbol ester after 2 days resulted in restoration of the enzyme activity in less than 1 h, and readdition of the phorbol ester again increased the activity by fivefold. When NGF was added to these neurons (1 microgram for 15 min), there was no change in the enzyme activity. Phorbol 13-acetate was ineffective in supporting sympathetic neurons in culture, as well as in enhancing protein kinase C activity. We also compared the protein kinase C activity of sympathetic neurons supported in culture by NGF and excess potassium (35 mM K+) Neurons supported in culture by 35 mM K+ for 2 days had almost eightfold more protein kinase C activity in their particulate fraction than in cytosol fraction. In NGF-supported neurons were acutely treated with excess K+, the protein kinase C activity was increased in the particulate fraction by about sevenfold in a concentration- and time-dependent manner. Excess K+ plus phorbol ester did not produce an additive effect on protein kinase C activity. PDB and excess K+ had no effect on cyclic AMP content of sympathetic neurons. In summary, the present data suggest that the neurotrophic action of PDB and excess K+ is probably mediated through protein kinase C.
Topics: Animals; Cell Survival; Chick Embryo; Cyclic AMP; Enzyme Activation; Ions; Nerve Growth Factors; Neurons; Norepinephrine; Phorbol 12,13-Dibutyrate; Phorbol Esters; Potassium; Protein Kinase C; Sympathetic Nervous System
PubMed: 2842460
DOI: 10.1111/j.1471-4159.1988.tb01835.x -
Neuroscience Letters Oct 1996The effects of protein kinase C (PKC) activation by phorbol ester on intracellular Ca2+ concentration ([Ca2+]i) and membrane currents in human microglia grown in culture...
The effects of protein kinase C (PKC) activation by phorbol ester on intracellular Ca2+ concentration ([Ca2+]i) and membrane currents in human microglia grown in culture were investigated. Treatment of microglia with phorbol myristate acetate (PMA) resulted in a large increase in [Ca2+]i in cells loaded with fura-2. The increased levels of [Ca2+]i were not altered following removal of the phorbol ester. In Ca(2+)-free medium, application of PMA did not increase [Ca2+]i. In addition, PMA application in standard Ca(2+)-solution containing lanthanum (1.8 mM) had no effect on the microglial response to PMA, suggesting that the phorbol ester actions were due to transmembrane influx of Ca2+ but not through voltage-gated Ca2+ channels. Whole-cell patch clamp measurements demonstrated that PMA potentiated an outward K+ current and inhibited an inward rectifier K+ current. This study is the first demonstration that PKC activation by phorbol ester leads to increased intracellular [Ca2+] and changes in membrane currents in human microglia.
Topics: Brain; Calcium; Cells, Cultured; Fetus; Humans; Membrane Potentials; Microglia; Phorbol Esters
PubMed: 8939475
DOI: 10.1016/0304-3940(96)13120-7 -
Cancer Research Apr 1988The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) has been shown previously to mimic X-irradiation in altering cell cycle parameters in Hela cells [Kinzel,...
The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) has been shown previously to mimic X-irradiation in altering cell cycle parameters in Hela cells [Kinzel, V., Richards, J., and Stöhr, M., Science (Wash. DC), 210: 429-431, 1980]. These changes include a delay in G2 phase from which cells recover in the presence of TPA, which suggests an involvement of cellular mediators. In order to obtain information on the onset and the duration of the G2 delay, as well as the onset and rate of recovery, a time-lapse study has been carried out. The analysis of cells in prophase shows that at 10(-6) M and 10(-7) M concentrations, TPA and 12-O-retinoylphorbol-13-acetate (RPA) cause a G2 delay which lasts on the order of 3.5 to 4 h. Below 10(-7) M of RPA and below 10(-8) M of TPA a clear-cut inhibition of HeLa cells in G2 is no longer detectable by this method. These results for a given phorbol ester are dose dependent within a certain range but unlike the case of X-rays are not proportional to dose. Within the dose range studied the recovery rate follows the opposite order. At 10(-6) M TPA and RPA an indication of a parasynchronous burst is observed. At smaller concentrations or with less biological activity of phorbol ester, the cell multiplication rate approaches that of the control or remains even smaller. Possible reasons are discussed. The determination of the transition points seems to indicate that the cellular events inhibited in G2 occur shortly before visible prophase.
Topics: Cell Cycle; HeLa Cells; Humans; In Vitro Techniques; Interphase; Mitosis; Motion Pictures; Phorbol Esters
PubMed: 3349455
DOI: No ID Found -
Journal of Immunology (Baltimore, Md. :... Sep 1986Phorbol esters have been used to study changes in the adhesiveness of T cells to endothelial cells (EC) after activation. The phorbol esters... (Comparative Study)
Comparative Study
Phorbol esters have been used to study changes in the adhesiveness of T cells to endothelial cells (EC) after activation. The phorbol esters 12-O-tetra-decanoylphorbol-13-acetate (TPA) and 4-beta-phorbol-12,13-dibutyrate (P(Bu)2), but not the biologically inert 4-alpha-phorbol-12,13-didecanoate, strongly increased the binding of 51Cr-labeled T cells to human umbilical vein EC monolayers in microtiter wells. Binding to fibroblasts and gelatin-coated plastic was also increased, but to a lesser extent. Increased binding was observed at 0.3 ng/ml, with maximal enhancement at 33 to 100 ng/ml. Enhancement occurred within 1 min, with maximal increase after 15 min. Preincubation studies with P(Bu)2 showed that binding enhancement was entirely attributable to an effect on T cells, with no action on EC. Additive binding enhancement was seen when phorbol esters and agents that alter adhesion by acting on EC (LPS, IL 1, or IFN-gamma) were used together. The increase in T cell adhesion to EC after T cell activation may contribute to the selective emigration of activated T cells from the blood into developing inflammatory lesions. The rapid increase in binding suggests that this may be an important mechanism for immediate localization of circulating T cells, particularly sensitized T cells, in the cellular immune response, perhaps involving the activation of these cells at the endothelial blood-tissue interface.
Topics: Cell Adhesion; Cells, Cultured; Endothelium; Fibroblasts; Gelatin; Humans; Interferon-gamma; Interleukin-1; Lipopolysaccharides; Phorbol 12,13-Dibutyrate; Phorbol Esters; Phorbols; T-Lymphocytes; Tetradecanoylphorbol Acetate; Umbilical Veins
PubMed: 3091681
DOI: No ID Found -
Biochemical Pharmacology Nov 2000The phorbol ester tumor promoters and related analogs are widely used as potent activators of protein kinase C (PKC). The phorbol esters mimic the action of the lipid...
The phorbol ester tumor promoters and related analogs are widely used as potent activators of protein kinase C (PKC). The phorbol esters mimic the action of the lipid second messenger diacylglycerol (DAG). The aim of this commentary is to highlight a series of important and controversial concepts in the pharmacology and regulation of phorbol ester receptors. First, phorbol ester analogs have marked differences in their biological properties. This may be related to a differential regulation of PKC isozymes by distinct analogs. Moreover, it seems that marked differences exist in the ligand recognition properties of the C1 domains, the phorbol ester/DAG binding sites in PKC isozymes. Second, an emerging theme that we discuss here is that phorbol esters also target receptors unrelated to PKC isozymes, a concept that has been largely ignored. These novel receptors lacking kinase activity include chimaerins (a family of Rac-GTPase-activating proteins), RasGRP (a Ras exchange factor), and Unc-13/Munc-13 (a family of proteins involved in exocytosis). Unlike the classical and novel PKCs, these "non-kinase" phorbol ester receptors possess a single copy of the C1 domain. Interestingly, each receptor class has unique pharmacological properties and biochemical regulation. Lastly, it is well established that phorbol esters and related analogs can translocate each receptor to different intracellular compartments. The differential pharmacological properties of the phorbol ester receptors can be exploited to generate specific agonists and antagonists that will be helpful tools to dissect their cellular function.
Topics: Animals; Biological Transport; Caenorhabditis elegans Proteins; Carcinogens; Carrier Proteins; Conserved Sequence; Diglycerides; Enzyme Activation; Humans; Isoenzymes; Molecular Mimicry; Phorbol Esters; Protein Conformation; Protein Kinase C; Receptors, Drug; Second Messenger Systems
PubMed: 11020443
DOI: 10.1016/s0006-2952(00)00470-6 -
The Protein Journal Dec 2018Protein kinase C (PKC) is a family of signal transducing enzymes that have been implicated in anesthetic preconditioning signaling cascade. Evidences are emerging that... (Comparative Study)
Comparative Study
Protein kinase C (PKC) is a family of signal transducing enzymes that have been implicated in anesthetic preconditioning signaling cascade. Evidences are emerging that certain exogenous neuromodulators such as n-alkanols and general anesthetics can stimulate PKC activity by binding to regulatory C1A domain of the enzyme. However, the accurate binding sites in C1A domain as well as the molecular mechanism underlying binding-stimulated PKC activation still remain unelucidated. Here, we report a systematic investigation of the intermolecular interaction of human PKCδ C1A domain with its natural activator phorbol ester (PE) and co-activator dioleoylglycerol (DOG) as well as exogenous stimulators butanol, octanol and sevoflurane. The domain is computationally identified to potentially have three spatially vicinal ligand-binding pockets 1, 2 and 3, in which the pockets 1 and 2 have previously been determined as the binding sites of PE and DOG, respectively. Systematic cross-binding analysis reveals that long-chain octanol and DOG are well compatible with the flat, nonpolar pocket 2, where the nonspecific hydrophobic contacts and van der Waals packing are primarily responsible for the binding, while the general anesthetic sevoflurane prefer to interact with the rugged, polar pocket 3 through specific hydrogen bonds and electrostatic forces. Short-chain butanol appears to bind effectively none of the three pockets. In addition, the pocket 1 consists of two angled arms 1 and 2 that are also involved in pockets 2 and 3, respectively. Dynamics characterization imparts that binding of long-chain octanol and DOG to pocket 2 or binding of sevoflurane to pocket 3 can induce a conformational displacement in arm 1 or 2, thus further opening the included angle and enlarging pocket 1, which can improve the pocket 1-PE affinity via an allosteric mechanism, consequently stimulating the PE-induced PKCδ activation.
Topics: Butanols; Diglycerides; Humans; Molecular Dynamics Simulation; Octanols; Phorbol Esters; Protein Domains; Protein Kinase C-delta; Sevoflurane
PubMed: 30251087
DOI: 10.1007/s10930-018-9793-7 -
The American Journal of Physiology Sep 1986We studied the contractile response to phorbol esters and its relationship to myosin light chain phosphorylation in intact and Triton X-100-skinned porcine carotid...
We studied the contractile response to phorbol esters and its relationship to myosin light chain phosphorylation in intact and Triton X-100-skinned porcine carotid preparations. Muscle contraction was activated by phorbol 12,13-dibutyrate (PDBu) and phorbol 12,13-didecanoate (PDD). Dose-dependent contractions to PDBu were obtained both in the intact and skinned preparations. The maximal values of stress in response to PDBu were 1.11 +/- 0.10 X 10(5) N/m2 (n = 7) in the intact and 5.72 +/- 0.59 X 10(4) N/m2 (n = 10) in the skinned muscles. The skinned tissues responded to PDD, which has been shown to activate protein kinase C, but not to the inactive isomer 4 alpha-PDD, thus ruling out nonspecific phorbol effects. The phorbol ester response exhibited a Ca2+ dependence. High stresses in the skinned muscles (5.53 +/- 0.69 X 10(4) N/m2, n = 8) were associated with low values of myosin light chain phosphorylation (0.18 +/- 0.01 mol Pi/mol light chain, n = 8). Thus phorbol esters can contract vascular smooth muscle by a mechanism that is not proportional to myosin light chain phosphorylation and that may involve activation of protein kinase C.
Topics: Animals; Calcium; Carotid Arteries; Enzyme Activation; Kinetics; Muscle Contraction; Muscle, Smooth, Vascular; Myosins; Phorbol 12,13-Dibutyrate; Phorbol Esters; Phosphorylation; Potassium; Protein Kinase C; Skin Physiological Phenomena; Swine; Tetradecanoylphorbol Acetate
PubMed: 3463215
DOI: 10.1152/ajpcell.1986.251.3.C356