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Scientific Reports Oct 2016An important, irreversible step in many signalling pathways is the shedding of membrane-anchored proteins. A Disintegrin And Metalloproteinase (ADAM) 17 is one of the...
An important, irreversible step in many signalling pathways is the shedding of membrane-anchored proteins. A Disintegrin And Metalloproteinase (ADAM) 17 is one of the major sheddases involved in a variety of physiological and pathophysiological processes including regeneration, differentiation, and cancer progression. This central role in signalling implies that ADAM17 activity has to be tightly regulated, including at the level of localisation. Most mature ADAM17 is localised intracellularly, with only a small amount at the cell surface. We found that ADAM17 is constitutively internalised by clathrin-coated pits and that physiological stimulators such as GPCR ligands induce ADAM17-mediated shedding, but do not alter the cell-surface abundance of the protease. In contrast, the PKC-activating phorbol ester PMA, often used as a strong inducer of ADAM17, causes not only proteolysis by ADAM17 but also a rapid increase of the mature protease at the cell surface. This is followed by internalisation and subsequent degradation of the protease. Eventually, this leads to a substantial downregulation of mature ADAM17. Our results therefore imply that physiological activation of ADAM17 does not rely on its relocalisation, but that PMA-induced PKC activity drastically dysregulates the localisation of ADAM17.
Topics: ADAM17 Protein; Cell Membrane; Clathrin-Coated Vesicles; Down-Regulation; Enzyme Activation; HEK293 Cells; HeLa Cells; Humans; Phorbol Esters; Protein Kinase C; Proteolysis; Signal Transduction
PubMed: 27731361
DOI: 10.1038/srep35067 -
The Journal of Cell Biology Jul 1984The human, leukemic cell line, HL-60, undergoes differentiation in response to tumor-promoting phorbol esters. Recent studies have implicated stimulation of a Na+/H+...
The human, leukemic cell line, HL-60, undergoes differentiation in response to tumor-promoting phorbol esters. Recent studies have implicated stimulation of a Na+/H+ antiporter as an initial event in cellular differentiation and/or proliferation. The effects of phorbol esters on Na+-dependent H+ efflux from HL-60 cells were studied by pH-stat titration. Tumor-promoting phorbol diesters, but not the inactive parent alcohol, stimulated Na+-dependent H+ efflux in a rapid (within 1 min at 37 degrees C) and reversible manner. Stimulation was dependent on the concentration of extracellular sodium; lithium could substitute for sodium, but choline could not. Stimulation was dependent on the activity of extracellular protons and was inhibited completely by amiloride. The concentrations of phorbol diesters at which we observed half-maximal stimulation of Na+-dependent H+ efflux are very similar to the Kd reported in the literature for binding of these phorbol diesters to the phorbol ester receptor and the Km for phorbol diester activation of protein kinase C. Overall characterization of basal and phorbol ester-stimulated H+ efflux indicate that stimulation of a Na+/H+ antiporter constitutes a primary event in phorbol ester interaction with HL-60 cells.
Topics: Amiloride; Carrier Proteins; Cell Line; Humans; Kinetics; Leukemia, Myeloid, Acute; Phorbol 12,13-Dibutyrate; Phorbol Esters; Phorbols; Pyrazines; Sodium-Hydrogen Exchangers; Tetradecanoylphorbol Acetate
PubMed: 6330130
DOI: 10.1083/jcb.99.1.340 -
Cellular and Molecular Neurobiology Sep 19881. Calcium-dependent exocytosis of catecholamines from intact and digitonin-permeabilized bovine adrenal chromaffin cells was investigated. 2. 45Ca2+ uptake and... (Review)
Review
1. Calcium-dependent exocytosis of catecholamines from intact and digitonin-permeabilized bovine adrenal chromaffin cells was investigated. 2. 45Ca2+ uptake and secretion induced by nicotinic stimulation or depolarization in intact cells were closely correlated. The results provide strong support for Ca2+ entry being the trigger for exocytosis. 3. Experiments in which the H+ electrochemical gradient across the intracellular secretory granule (chromaffin granule) membrane was altered indicated that the gradient does not play an important role in exocytosis. 4. Ca2+ entry into the cells is associated with activation of phospholiphase C and a rapid translocation of protein kinase C to membranes. 5. The plasma membrane of chromaffin cells was rendered permeable to Ca2+, ATP, and proteins by the detergent digitonin without disruption of the intracellular secretory granules. In this system in which the intracellular milieu can be controlled, micromolar Ca2+ directly stimulated catecholamine secretion. 6. Treatment of the cells with phorbol esters and diglyceride, which activate protein kinase C, enhanced phosphorylation and subsequent Ca2+-dependent secretion in digitonin-treated cells. 7. Phorbol ester-induced secretion could be specifically inhibited by trypsin. The experiments indicate that protein kinase C modulates but is not necessary for Ca2+-dependent secretion.
Topics: Adrenal Medulla; Animals; Calcium; Catecholamines; Cattle; Digitonin; Exocytosis; Phorbol Esters; Phosphorylation
PubMed: 3066486
DOI: 10.1007/BF00711168 -
Molecular Pharmacology Sep 2010Bryostatin 1, a macrocyclic lactone that has been widely characterized as an ultrapotent protein kinase C (PKC) activator, displays marked pharmacological differences...
Bryostatin 1 inhibits phorbol ester-induced apoptosis in prostate cancer cells by differentially modulating protein kinase C (PKC) delta translocation and preventing PKCdelta-mediated release of tumor necrosis factor-alpha.
Bryostatin 1, a macrocyclic lactone that has been widely characterized as an ultrapotent protein kinase C (PKC) activator, displays marked pharmacological differences with the typical phorbol ester tumor promoters. Bryostatin 1 impairs phorbol 12-myristate 13-acetate (PMA)-induced tumor promotion in mice and is in clinical trials as an anticancer agent for a number of hematopoietic malignancies and solid tumors. In this study, we characterized the effect of bryostatin 1 on LNCaP prostate cancer cells, a cellular model in which PKC isozymes play important roles in the control of growth and survival. Although phorbol esters promote a strong apoptotic response in LNCaP cells via PKCdelta-mediated release of TNFalpha, bryostatin 1 failed to trigger a death effect even at high concentrations, and it prevented PMA-induced apoptosis in these cells. Mechanistic analysis revealed that bryostatin 1 is unable to induce TNFalpha release, and it impairs the secretion of this cytokine from LNCaP cells in response to PMA. Unlike PMA, bryostatin 1 failed to promote the translocation of PKCdelta to the plasma membrane. Moreover, bryostatin 1 prevented PMA-induced PKCdelta peripheral translocation. Studies using a membrane-targeted PKCdelta construct revealed that the peripheral localization of the kinase is a requisite for triggering apoptosis in LNCaP cells, arguing that mislocalization of PKCdelta may explain the actions of bryostatin 1. The identification of an antiapoptotic effect of bryostatin 1 may have significant relevance in the context of its therapeutic efficacy.
Topics: Antineoplastic Agents; Apoptosis; Bryostatins; Humans; Isoenzymes; Lactones; Male; Phorbol Esters; Prostatic Neoplasms; Protein Kinase C; Protein Kinase C-delta; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha
PubMed: 20516369
DOI: 10.1124/mol.110.064741 -
The Journal of Biological Chemistry Feb 1986The phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) caused phosphorylation of phosphoproteins of 56-kDa which co-migrated with and had identical pI values to...
The phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) caused phosphorylation of phosphoproteins of 56-kDa which co-migrated with and had identical pI values to subunits of tyrosine hydroxylase. The phosphorylation was closely correlated with an increase of [3H]3,4-dihydroxyphenylalanine (DOPA) production which is a reflection of increased tyrosine hydroxylase activity. Only those phorbol esters which activate protein kinase C induced phosphorylation of the 56-kDa proteins and increased [3H]DOPA production. Neither TPA-induced phosphorylation of the 56-kDa proteins nor TPA-induced enhancement of [3H] DOPA production required extracellular Ca2+. TPA caused increases in phosphorylation of the 56-kDa proteins and increases in [3H]DOPA production over similar concentration ranges (10-1000 nM). TPA did not increase cellular cAMP. The data suggest that phorbol ester-induced phosphorylation of intracellular tyrosine hydroxylase, possibly by protein kinase C, results in increased tyrosine hydroxylase activity.
Topics: Adrenal Medulla; Animals; Cattle; Cells, Cultured; Chromaffin System; Dihydroxyphenylalanine; Enzyme Activation; Phorbol Esters; Phosphoproteins; Phosphorylation; Protein Kinase C; Receptors, Muscarinic; Receptors, Nicotinic; Stimulation, Chemical; Tetradecanoylphorbol Acetate; Tyrosine 3-Monooxygenase
PubMed: 2868006
DOI: No ID Found -
The Journal of Biological Chemistry Nov 1991The mechanism by which phorbol esters induce hypertrophic growth of cardiomyocytes was investigated. Control and 4 alpha-phorbol 12,13-didecanoate-treated myocytes...
The mechanism by which phorbol esters induce hypertrophic growth of cardiomyocytes was investigated. Control and 4 alpha-phorbol 12,13-didecanoate-treated myocytes demonstrated a slow rate of growth as measured by the protein/DNA ratio and cell area. In contrast, treatment with phorbol 12-myristate 13-acetate (PMA) stimulated protein accumulation by 34%, while cell area was increased by 68% over control myocytes after 72 h. RNA content in PMA-treated myocytes was 33% higher than in control cells and 4 alpha-phorbol 12,13-didecanoate-treated cells after 72 h. Membrane-associated protein kinase C activity was transiently increased after PMA treatment but returned to normal by 48 h. Cytosolic protein kinase C activity was not significantly altered by PMA. Membrane-associated and cytosolic protein kinase C activities were not altered by 4 alpha-phorbol 12,13-didecanoate. Protein kinase C activity, RNA polymerase I activity, and the transcriptional rate of ribosomal DNA (rDNA) were increased in nuclei isolated from PMA-treated cells. However, consistent with a high rate of processing of pre-ribosomal RNA (pre-rRNA), the pool size of pre-rRNA relative to the 28 S rRNA was unaltered by PMA treatment. These data demonstrated that PMA-induced hypertrophic growth of cardiomyocytes was due to an increase in the capacity for protein synthesis (rRNA), and suggest that this results from protein kinase C mediated increase in the rate of transcription of rDNA.
Topics: Animals; Animals, Newborn; Carcinogens; Cell Division; Cell Nucleus; Cells, Cultured; DNA, Ribosomal; Heart; Kinetics; Myocardium; Phorbol Esters; Protein Kinase C; RNA Precursors; Tetradecanoylphorbol Acetate; Transcription, Genetic
PubMed: 1939221
DOI: No ID Found -
The American Journal of Pathology Jan 1990The neoplastic Hodgkin's Reed-Sternberg (H-RS) cells in Hodgkin's disease are surrounded in vivo by abundant reactive cells, the function of which may be attributed in... (Comparative Study)
Comparative Study
Lack of effect of colony-stimulating factors, interleukins, interferons, and tumor necrosis factor on the growth and differentiation of cultured Reed-Sternberg cells. Comparison with effects of phorbol ester and retinoic acid.
The neoplastic Hodgkin's Reed-Sternberg (H-RS) cells in Hodgkin's disease are surrounded in vivo by abundant reactive cells, the function of which may be attributed in part to their elaboration of various cytokines. Thus, a study of the interaction of H-RS cells with exogenous cytokines may provide information as to the mechanism of the clinical and histopathologic changes observed in Hodgkin's disease. This study examined the effect of various cytokines, and of phorbol ester (TPA) and retinoic acid, on the differentiation and proliferation of cultured H-RS cells (cell lines HDLM-1 and KM-H2). In addition, it was determined whether these cells were able to secrete cytokines after being treated with exogenous cytokines. The cytokines used included various types of interleukins (1, 2, and 3), colony-stimulating factors (GM, G, and M), interferons (alpha, beta, and gamma), and tumor necrosis factor (alpha). It was found that these cytokines, used alone or in combination, were not effective in modulating the proliferation and differentiation of cells, or the production of cytokines, in cultured H-RS cells. In contrast, this study revealed that retinoic acid can potentiate TPA-induced growth inhibition in cultured H-RS cells. Retinoic acid, when used alone, exhibited a minimal effect on cell differentiation. No synergistic effects of cytokines and retinoic acid on H-RS cells were observed. The failure of cultured H-RS cells to respond to exogenous cytokines suggests that, during the course of neoplastic transformation, of progression of disease, or of establishment of the cells in culture, H-RS cells lose their dependence on cytokines, although they retain the capacity to produce various cytokines.
Topics: Aged; Biological Factors; Cell Line; Cell Transformation, Neoplastic; Colony-Stimulating Factors; Cytokines; Hodgkin Disease; Humans; Interferons; Interleukins; Lymphoma; Male; Phorbol Esters; Tetradecanoylphorbol Acetate; Tretinoin; Tumor Necrosis Factor-alpha
PubMed: 1688689
DOI: No ID Found -
The Journal of Biological Chemistry Aug 2010Different levels of regulation account for the inactivation of MAP kinases by MAPK phosphatases (MKPs), in a cell type- and stimuli-dependent manner. MCF-7 human breast...
Differential up-regulation of MAP kinase phosphatases MKP3/DUSP6 and DUSP5 by Ets2 and c-Jun converge in the control of the growth arrest versus proliferation response of MCF-7 breast cancer cells to phorbol ester.
Different levels of regulation account for the inactivation of MAP kinases by MAPK phosphatases (MKPs), in a cell type- and stimuli-dependent manner. MCF-7 human breast carcinoma cells treated with the phorbol 12-myristate 13-acetate (PMA) suffer growth arrest and show morphological alterations, which depend on the activation of the ERK1/2 MAP kinases. MKP3/DUSP6 and DUSP5 MAP kinase phosphatases, two negative regulators of ERK1/2, were specifically up-regulated in MCF-7 and SKBR3 cells in response to PMA. MKP3 and DUSP5 up-regulation required the prolonged activation of the ERK1/2 pathway, and correlated with the shutdown of this route. MKP3 induction relied on the activation of the Ets2 transcription factor, whereas DUSP5 induction depended on the activation of c-Jun. Diminishing the expression of MKP3 and DUSP5 raised the activation of ERK1/2, and accelerated growth arrest of PMA-treated MCF-7 cells. Conversely, MCF-7 cell lines expressing high levels of MKP3 or DUSP5 did not undergo PMA-triggered growth arrest, displayed a migratory phenotype, and formed colonies in soft agar. We propose that the differential up-regulation of MKP3 by Ets2 and of DUSP5 by c-Jun may converge in similar functional roles for these MAP kinase phosphatases in the growth arrest versus proliferation decisions of breast cancer cells.
Topics: Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Dual Specificity Phosphatase 6; Dual-Specificity Phosphatases; Female; Humans; Phorbol Esters; Proto-Oncogene Protein c-ets-2; Proto-Oncogene Proteins c-jun; Up-Regulation
PubMed: 20554528
DOI: 10.1074/jbc.M110.121830 -
The Journal of Biological Chemistry Nov 2000Cellular prion protein (PrP(c)) undergoes a proteolytic attack at the 110/111 downward arrow112 peptide bond, whereas the PrP isoform (PrP(res)) that accumulates in the...
Cellular prion protein (PrP(c)) undergoes a proteolytic attack at the 110/111 downward arrow112 peptide bond, whereas the PrP isoform (PrP(res)) that accumulates in the brain tissue in Creutzfeldt-Jakob disease reveals an alternate cleavage site at about residue 90. Interestingly, the normal processing of PrP occurs inside the 106-126 amino acid region thought to be responsible for the neurotoxicity of the pathogenic prions, whereas PrP(res) cleavage preserves this potentially toxic domain. Therefore, any molecular mechanisms leading to enhanced cleavage at the 110/111 downward arrow112 peptide bond could be of potential interest. We set up TSM1 neurons and HEK293 stable transfectants overexpressing the wild-type or 3F4-tagged murine PrP(c), respectively. Both mock-transfected and PrP(c)-expressing cell lines produced an 11-12-kDa PrP fragment (referred to as N1), the immunological characterization of which strongly suggests that it corresponds to the N-terminal PrP(c) fragment derived from normal processing. We have established that the recovery of secreted N1 is increased by the protein kinase C agonists PDBu and PMA in a time- and dose-dependent manner in both cell lines. In contrast, secretion of N1 remains unaffected by the inactive PDBu analog alphaPDD and by the protein kinase A effectors dibutyryl cAMP and forskolin. Overall, our data indicate that the normal processing of PrP(c) is up-regulated by protein kinase C but not protein kinase A in human cells and murine neurons.
Topics: Amino Acid Sequence; Animals; Blotting, Western; Bucladesine; Carcinogens; Cell Line; Colforsin; Cyclic AMP-Dependent Protein Kinases; Dose-Response Relationship, Drug; Humans; Kinetics; Methanol; Mice; Molecular Sequence Data; Neurons; Phorbol 12,13-Dibutyrate; Phorbol Esters; Precipitin Tests; Prions; Protein Isoforms; Protein Kinase C; Tetradecanoylphorbol Acetate; Time Factors; Transfection; Up-Regulation
PubMed: 10952979
DOI: 10.1074/jbc.M004628200 -
British Journal of Pharmacology May 19931. Effects of phorbol esters on the cytosolic Ca2+ level ([Ca2+]i) and muscle tension in the intestinal smooth muscle of guinea-pig taenia caeci were examined. 2....
1. Effects of phorbol esters on the cytosolic Ca2+ level ([Ca2+]i) and muscle tension in the intestinal smooth muscle of guinea-pig taenia caeci were examined. 2. 12-Deoxyphorbol 13-isobutyrate (DPB, 1 microM) did not change the [Ca2+]i and tension in resting muscle. 3. In high K(+)-stimulated muscle, 1 microM DPB transiently augmented the contraction and decreased [Ca2+]i. 12-Deoxyphorbol 13-isobutyrate 20-acetate (1 microM) and phorbol 12, 13-dibutyrate (1 microM) showed similar effects to DPB whereas phorbol 12-myristate 13-acetate (1 microM) and phorbol 12, 13-didecanoate (1 microM) were ineffective. 4. DPB (1 microM) inhibited both [Ca2+]i and tension stimulated by 300 nM carbachol or 3 microM histamine. In the presence of a higher concentration of carbachol (1 microM), DPB decreased [Ca2+]i and transiently increased muscle tension. 5. In the muscle strips permeabilized with bacterial alpha-toxin, 1 microM DPB shifted the Ca(2+)-tension curve to the left. An inhibitor of protein kinase C, H-7 (30 microM), inhibited the effect of DPB. 6. DPB did not change the high K(+)-induced contraction in the muscle strips pretreated with 3 microM phorbol 12-myristate 13-acetate for 24 h. 7. These results suggest that activation of protein kinase C has dual effects; it augments contraction by increasing the Ca2+ sensitivity of the contractile elements and it inhibits contraction by decreasing [Ca2+]i.
Topics: Animals; Calcium; Cecum; Cytosol; Down-Regulation; Guinea Pigs; In Vitro Techniques; Male; Muscle Contraction; Muscle Relaxation; Muscle, Smooth; Phorbol Esters; Potassium; Protein Kinase C
PubMed: 8495240
DOI: 10.1111/j.1476-5381.1993.tb13558.x