Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Normal human melanocytes are often grown in vitro in the continuous presence of 12-O-tetradecanoylphorbol-13-acetate (TPA) for growth in vitro. The expression of protein kinase C (PKC) subspecies, which are the major cellular receptors for phorbol esters, was examined in melanocytes after long-term treatment with TPA to investigate the role of PKC subspecies in TPA-dependent cell growth. The PKC enzyme activity detected in quiescent melanocytes was almost completely depleted in cells after incubation with 85 nM TPA for 48 h. Immunoblot analysis indicated that, among the PKC subspecies alpha, beta, delta, epsilon, and zeta expressed in quiescent cells, alpha-, beta-, delta-, and epsilon-PKC were significantly down-regulated, whereas zeta-PKC remained at detectable levels in TPA-treated cells. TPA did not significantly affect the expression or subcellular distribution of zeta-PKC in melanocytes. Immunoprecipitation assay revealed that the enzyme activity of zeta-PKC was increased in both the cytosol and particulate cell fractions, but the increase was much greater in the latter. The activation of zeta-PKC lasted for 24 to 48 h after the addition of TPA; thereafter, zeta-PKC activity returned to basal levels. DNA synthesis was shown to change concomitantly with the activation of zeta-PKC in TPA-treated cells. These results indicate that TPA induces not only the down-regulation of alpha-, beta-, delta-, and epsilon-PKC, but also long-term activation of zeta-PKC in melanocytes, and that activation of zeta-PKC parallels the growth of normal human melanocytes.
J Invest Dermatol 1995 Oct
PMID:Differential down-regulation of protein kinase C subspecies in normal human melanocytes: possible involvement of the zeta subspecies in growth regulation. 756 Nov 60

Exposure of human and murine melanocytes in vitro to the diacylglycerol (DAG) 1-oleoyl-2-acetyl-sn-glycerol (OAG) markedly increases melanin production within 24 h. To determine whether OAG can increase melanin production in vivo, increasing concentrations of OAG (10-60 mg/ml) in propylene glycol were applied daily for 5 d to shaved guinea pigs. Dose-dependent increased pigmentation was visible first on days 17-22 and persisted for 10-14 weeks. Peak epidermal melanin content in OAG-treated sites was more than twice that of untreated or vehicle-treated sites, as assessed by computerized image analysis of Fontana-Masson stained biopsy cross sections. In another experiment to assess the mechanism of DAG-mediated pigmentation, guinea pigs received twice daily separate applications of OAG, dipalmitoylglycerol (diC16), dioctanoylglycerol (diC8), each 50 mg/ml, 20 microliters/application, and propylene glycol vehicle alone for 5 d. Increased pigmentation was visible after 10 d in the OAG and diC8 sites but not in diC16 or vehicle sites. These results correlate with the reported ability of these compounds to activate protein kinase C in vitro. In a final experiment, guinea pigs received OAG 25 mg/ml three times daily to one test site, and once daily ultraviolet B (70 mJ/cm2, equivalent to 0.6 minimal erythemal dose) radiation to another for 10 d. The OAG and ultraviolet B test sites developed comparable pigmentation by both clinical and histologic criteria. Our data demonstrate that topically applied DAGs can produce a long-lasting increase in epidermal pigmentation, presumably through protein kinase C activation, which clinically and histologically closely resembles ultraviolet-induced tanning.
J Invest Dermatol 1995 Nov
PMID:Topically applied diacylglycerols increase pigmentation in guinea pig skin. 898 Mar 2

Eosinophils represent major effector cells in the allergic inflammatory response. Following activation, these cells are capable of mediating tissue damage, particularly by the release of reactive oxygen species. In this study, the role of extracellular and intracellular calcium in the induction of the respiratory burst of human eosinophils was investigated in healthy non-atopic individuals. Pre-incubation of Fura-2-loaded eosinophils with the intracellular calcium chelator 2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid prevented the increase of the [Ca++]i following stimulation by RANTES, C5a and PAF, in concentration-dependent fashion, whereas depletion of extracellular calcium in the test medium by ethyl=eneglycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid was ineffective. To investigate the potential role of extracellular and intracellular calcium on the production of reactive oxygen species, flow-cytometric measurement of H2O2 production by dihydrorhodamine 123 and lucigenin-dependent chemiluminescence were carried out. Chelation of both intracellular and extracellular calcium prevented production of reactive oxygen species after stimulation with C5a, PAF, or RANTES. However, production of reactive oxygen species after stimulation by phorbol myristate acetate, which bypasses post-receptor events by direct activation of protein kinase C, was prevented only after chelation of intracellular but not extracellular calcium. This suggested a Ca(++)-sensitive form of protein kinase C in the activation process of the respiratory burst. These data demonstrate that intracellular and extracellular calcium represent a prerequisite of chemotaxin-induced activation of the respiratory burst in human eosinophils. Thus, intracellular calcium seems to play a central role in the modulation of the respiratory burst in eosinophils and might therefore be an interesting target for drugs that interfere with calcium homeostasis and reduce the tissue destructive power of eosinophils.
J Invest Dermatol 1995 Aug
PMID:Activation of the respiratory burst in human eosinophils by chemotaxins requires intracellular calcium fluxes. 763 6

In previous studies, Phorbol-12-myristate-13-acetate (PMA)-treated human keratinocytes (PMA-HNK) were shown to induce T-cell proliferation via a major histocompatibility complex (MHC)- and antigen (Ag)-independent mechanism, that was mediated in part by PMA-induced intercellular adhesion molecule (ICAM)-1 on HNK. Recently, the interaction of the B7 Ag on antigen-presenting cells with its ligand CD28 on T cells has been shown to deliver activation signals distinct from the interaction of MHC/Ag with the T-cell receptor. These findings led us to assess whether B7-dependent signals play a role in T-cell proliferation induced by PMA-HNK. We first examined B7 expression on HNK by staining with three different monoclonal antibodies (MoAbs). When analyzed by fluorescence-activated cell sorter, untreated HNK stained only faintly. By contrast, PMA induced a dose-dependent upregulation of B7 staining. This staining identifies a molecule closely related to B7 because it was blocked by purified recombinant B7 immunoglobulin. Upregulation of B7 staining was first observed 16 h after PMA treatment and persisted for at least 48 h; it was protein kinase C dependent and required de novo protein synthesis. Anti-B7 MoAbs reduced specifically the capacity of PMA-HNK to trigger proliferation of allogeneic peripheral blood mononuclear cells and T cells. The combination of anti-B7 and anti-ICAM-1 MoAbs further reduced this response. We conclude that PMA upregulates on HNK the expression of a B7-like molecule that contributes in concert with ICAM-1 to the capacity of PMA-HNK to induce proliferation of allogeneic T cells.
J Invest Dermatol 1993 Mar
PMID:Phorbol-12-myristate-13-acetate-treated human keratinocytes express B7-like molecules that serve a costimulatory role in T-cell activation. 768 55

Intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and endothelial leukocyte adhesion molecule-1 (ELAM-1, E-selectin) are endothelial surface molecules that play a role for leukocyte recruitment to sites of inflammation, e.g., during contact hypersensitivity. We studied the effects of sensitizing agents (2,4-dinitro-benzenesulfonic acid, metal salt haptens) and chemically related substances on endothelial adhesion molecule expression. Using flow cytometry and an enzyme-linked immunosorbent assay, NiCl2 and, to a lesser extent, CoCl2 were found to up-regulate ICAM-1, VCAM-1, and ELAM-1 expression on cultured human umbilical vein endothelium whereas the other substances tested showed no effects. Induction of adhesion molecules by NiCl2 required de novo mRNA and protein synthesis. Up-regulation could be blocked by kinase inhibitor H-7 but not staurosporine, suggesting involvement of phosphorylation events independent of protein kinase C activation. Concomitant application of NiCl2 and neutralizing antibodies to IL-1 did not block up-regulation by the hapten demonstrating that the latter did not act via an IL-1-dependent autocrine mechanism. Regarding ELAM-1 induction, pre-treatment for 24 h with NiCl2 produced hyporesponsiveness to IL-1 and TNF-alpha upon restimulation, suggesting that NiCl2 and these cytokines may partially share a common pathway of activation. In addition, analysis of cultured foreskin specimens revealed that NiCl2 may induce up-regulation of ELAM-1 on microvascular endothelium in vivo. Our data demonstrate that both Ni++ and Co++ to which simultaneous contact sensitivity is frequently observed have the ability to directly up-regulate endothelial adhesion molecules. This shared property may represent an adjuvant mechanism that promotes sensitization and elicitation events in contact hypersensitivity to these haptens.
J Invest Dermatol 1993 Jun
PMID:Nickel chloride and cobalt chloride, two common contact sensitizers, directly induce expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and endothelial leukocyte adhesion molecule (ELAM-1) by endothelial cells. 768 25

All-trans retinoic acid is used topically for treating a variety of dermatologic conditions ranging from acne to photoaged skin. Although the clinical effects of retinoic acid treatment are often considerable, relatively little is known about the basic mechanisms underlying such effects. With the development of an in vivo human assay we have investigated the pleiotypic effects of topical retinoids from the histologic to the molecular. Histologically, retinoic acid induces epidermal proliferation and differentiation coupled with dermal fibroblast production of collagen. Immunologic effects include stimulation of the antigen-presenting capacity of Langerhans cells and induction of keratinocyte ICAM-1 expression. At the biochemical level, retinoic acid regulates transglutaminase and tyrosinase activities and activates protein kinase C. Both polar metabolites and stereoisomers of all-trans retinoic acid are also biologically active. Molecular biologic techniques have revealed that elevation of mRNA for cellular retinoic acid binding protein II is a retinoid-related event and that nuclear receptors such as retinoic acid receptors and retinoid X-receptors may transduce the retinoid response.
Arch Dermatol Res 1994
PMID:Human in vivo pharmacology of topical retinoids. 772 37

Bradykinin (BK) is one of the key mediators of inflammation and a weak mitogen. We have previously demonstrated that BK induced the generation of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) which caused Ca2+ mobilization in human keratinocytes. In this study, BK-induced Ca2+ responses were examined in primary cultured human keratinocytes by video imaging fluorescence microscopy using fura-2. Intracellular calcium concentration ([Ca2+]i) level increased to a peak within 30 s after BK addition and decreased gradually to the basal level. The existence of the broad shoulder in the [Ca2+]i profile was suggested to be due to the Ca2+ influx from the external medium, because this disappeared in the presence of 0.5 mM EGTA. Pretreatment with phorbol-12-myristate-13-acetate (PMA), a protein kinase C (PKC) activator, significantly resulted in reduction of the descending shoulder of BK-induced increase in [Ca2+]i. A 20-min pretreatment with PKC inhibitors, H-7 or staurosporine, reversed the decrease by PMA in the shoulder of BK-induced Ca2+ response. Furthermore, the BK-induced [45Ca] uptake was inhibited by EGTA and PMA. Ins(1,4,5)P3 generation induced by BK peaked at 20 s and returned to the basal level at 60 s. There were no significant differences in Ins(1,4,5)P3 levels at 20 and 60 s among the cells exposed to BK alone, BK with PMA pretreatment (20 min) and BK with PMA+H-7 pretreatment. These results suggest that the BK-induced Ca2+ influx, which was shown as shoulder, may be negatively modulated by PKC in primary cultured human keratinocytes.
J Dermatol Sci 1995 Mar
PMID:Involvement of protein kinase C in bradykinin-induced intracellular calcium increase in primary cultured human keratinocytes. 777 73

During the final stage of epidermal differentiation, activation of keratinocyte transglutaminase results in covalent crosslinking of a variety of proteins to form highly protective cornified cell envelopes. We have studied the regulation of keratinocyte transglutaminase (TGK) gene expression in murine epidermal keratinocytes induced to terminally differentiate in vitro by increasing the level of extracellular Ca++ or treatment with the protein kinase C (PKC) activator 12-O-tetradecanoylphorbol-13-acetate (TPA). Raising extracellular Ca++ induces squamous differentiation of cultured keratinocytes and elicits a concentration-dependent increase in expression of TGK mRNA; keratinocytes grown for 24 h in 0.12 mM Ca++ medium express approximately 12 times as much TGK mRNA as basal cells (grown in 0.05 mM Ca++ medium), whereas cultures exposed to 1.4 mM Ca++ express approximately 17 times as much. TPA induces squamous differentiation and TGK mRNA even in basal keratinocyte cultures grown in 0.05 mM Ca++ medium, suggesting that expression of this differentiation marker is regulated by the PKC signaling pathway. Induction of TGK mRNA in response to TPA treatment is transient, reaching a peak at 6-8 h and returning to baseline by 24 h. In contrast, elevation of TGK mRNA levels in response to Ca++ persists for at least 24 h. The increased abundance of TGK mRNA reflects increased transcription of the TGK gene, based on nuclear run-on analysis of Ca(++)- and TPA-treated keratinocytes. Induction of TGK mRNA by either TPA or Ca++ is blocked in the presence of cycloheximide, suggesting that a PKC-dependent protein factor is required for TGK gene expression in response to both stimuli. Furthermore, the accumulation of TGK mRNA in keratinocytes treated with TPA or Ca++ is blocked in cells treated with the PKC inhibitor GF 109203X or bryostatin. These results suggest that the induction of TGK gene expression by Ca++ is dependent on PKC, providing further support for the hypothesis that PKC plays a central role in regulating the late stages of epidermal differentiation.
J Invest Dermatol 1994 Apr
PMID:Protein kinase C regulates keratinocyte transglutaminase (TGK) gene expression in cultured primary mouse epidermal keratinocytes induced to terminally differentiate by calcium. 790 80

Interleukin-8 (IL-8) is a potent pro-inflammatory molecule present in high amounts in psoriatic skin. Here it may play an important role in the keratinocyte hyperproliferation and the neutrophil and T-lymphocyte infiltration associated with the disease. In this study the effect of protein kinase C inhibitors on IL-8 production by human keratinocytes in vitro was investigated. The anti-inflammatory and immunomodulatory compound auranofin ([1-thio-beta-D-glucopyranose-2,3,4,6-tetraacetato-S] [triethylphosphine] gold) is known to inhibit protein kinase C. In addition, auranofin has been shown to inhibit skin inflammation. As such, auranofin was also studied for its effect on IL-8 production. Auranofin and staurosporine, inhibitors of protein kinase C, inhibited phorbol-myristate-acetate-stimulated IL-8 production. Northern analysis of IL-8 mRNA revealed that the inhibition of IL-8 production was associated with an inhibition of IL-8 mRNA expression. In contrast, these compounds potentiated the minimal IL-8 protein and mRNA seen in response to interleukin-1 beta or tumor necrosis factor-alpha. These findings suggest that IL-8 synthesis may be either positively or negatively regulated by protein kinase C depending on the stimulus.
J Invest Dermatol 1994 Oct
PMID:Interleukin-8 production is regulated by protein kinase C in human keratinocytes. 793 Jun 75

The introduction of the techniques of molecular biology as tools to study skin carcinogenesis has provided more precise localization of biochemical pathways that regulate the tumor phenotype. This approach has identified genetic changes that are characteristic of each of the specific stages of squamous cancer pathogenesis: initiation, exogenous promotion, premalignant progression, and malignant conversion. Initiation can result from mutations in a single gene, and the Harvey allele of the ras gene family has been identified as a frequent site for initiating mutations. Heterozygous activating mutations in c-rasHa are dominant, and affected keratinocytes hyperproliferate and are resistant to signals for terminal differentiation. An important pathway impacted by c-rasHa activation is the protein kinase C (PKC) pathway, a major regulator of keratinocyte differentiation. Increased activity of PKC alpha and suppression of PKC delta by tyrosine phosphorylation contribute to the phenotypic consequences of rasHa gene activation in keratinocytes. Tumor promoters disturb epidermal homeostasis and cause selective clonal expansion of initiated cells to produce multiple benign squamous papillomas. Resistance to differentiation and enhanced growth rate of initiated cells impart a growth advantage when the epidermis is exposed to promoters. The frequency of premalignant progression varies among papillomas, and subpopulations at high risk for progression have been identified. These high-risk papillomas overexpress the alpha 6 beta 4 integrin and are deficient in transforming growth factor beta 1 and beta 2 peptides, two changes associated with a very high proliferation rate in this subset of tumors. The introduction of an oncogenic rasHa gene into epidermal cells derived from transgenic mice with a null mutation in the TGF beta 1 gene have an accelerated rate of malignant progression when examined in vivo. Thus members of the TGF beta gene family contribute a tumor-suppressor function in carcinogenesis. Accelerated malignant progression is also found with v-rasHa transduced keratinocytes from skin of mice with a null mutation in the p53 gene. The similarities in risk for malignant conversion by initiated keratinocytes from TG beta 1 and p53 null geneotypes suggest that a common, growth-related pathway may underly the tumor-suppressive functions of these proteins in the skin carcinogenesis model.
J Invest Dermatol 1994 Nov
PMID:Role of oncogenes and tumor suppressor genes in multistage carcinogenesis. 796 91


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