C Isoforms (c + isoform)

Distribution by Scientific Domains
Life Sciences60%

Kinds of C Isoforms

  • kinase c isoform
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  • protein kinase c isoform
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    Selected Abstracts

    Role of mitogen-activated protein kinase cascades in P2Y receptor-mediated trophic activation of astroglial cells ,

    DRUG DEVELOPMENT RESEARCH, Issue 2-3 2001
    Joseph T. Neary
    Abstract The trophic actions of extracellular nucleotides and nucleosides on astroglial cells in the central nervous system may be important in development as well as injury and repair. Here we summarize recent findings on the signal transduction mechanisms and gene expression that mediate the trophic effects of extracellular ATP on astrocyte cultures, with a particular emphasis on mitogenesis. Activation of ATP/P2Y receptors leads to the stimulation of mitogen-activated protein kinase (MAPK) cascades, which play a crucial role in cellular proliferation, differentiation, and survival. Inhibition of ERK and p38, members of two distinct MAPK cascades, interferes with the ability of extracellular ATP to stimulate astrocyte proliferation, thereby indicating their importance in mitogenic signaling by P2Y receptors. Signaling from P2Y receptors to ERK involves phospholipase D and a calcium-independent protein kinase C isoform, PKC; this pathway is independent of the phosphatidylinositol-phospholipase C / calcium pathway which is also coupled to P2Y receptors. Pharmacological studies suggest that astrocytes may express an as-yet uncloned P2Y receptor that recruits a novel MEK activator in the ERK cascade. Extracellular ATP can also potentiate fibroblast growth factor (FGF)-2-induced proliferation, and studies on interactions between ATP and FGF-2 signaling pathways have revealed that although ATP does not activate cRaf-1, the first protein kinase in the ERK cascade, it can reduce cRaf-1 activation by FGF-2. As intermediate levels of Raf activity stimulate the cell cycle, the partial inhibition of FGF-induced Raf activity by ATP may contribute to the enhancing effect of ATP on FGF-2-induced astrocyte proliferation. Activation of P2Y receptors also leads to nuclear signaling, and the use of DNA arrays has shown that treatment of astrocytes with extracellular ATP results in the up- and downregulation of a number of genes; studies to determine which of these genes are regulated by MAPKs are now in progress. Elucidation of the components of MAPK pathways linked to P2Y receptors and subsequent changes in gene expression may provide targets for a new avenue of drug development aimed at the management of astrogliosis which occurs in many types of neurological disorders and neurodegeneration. Drug Dev. Res. 53:158,165, 2001. Published 2001 Wiley-Liss, Inc. [source]

    Two conventional protein kinase C isoforms, , and ,I, are involved in the ATP-induced activation of volume-regulated anion channel and glutamate release in cultured astrocytes

    JOURNAL OF NEUROCHEMISTRY, Issue 6 2008
    Alena Rudkouskaya
    Abstract Volume-regulated anion channels (VRACs) are activated by cell swelling and are permeable to inorganic and small organic anions, including the excitatory amino acids glutamate and aspartate. In astrocytes, ATP potently enhances VRAC activity and glutamate release via a P2Y receptor-dependent mechanism. Our previous pharmacological study identified protein kinase C (PKC) as a major signaling enzyme in VRAC regulation by ATP. However, conflicting results obtained with potent PKC blockers prompted us to re-evaluate the involvement of PKC in regulation of astrocytic VRACs by using small interfering RNA (siRNA) and pharmacological inhibitors that selectively target individual PKC isoforms. In primary rat astrocyte cultures, application of hypoosmotic medium (30% reduction in osmolarity) and 20 ,M ATP synergistically increased the release of excitatory amino acids, measured with a non-metabolized analog of l -glutamate, d -[3H]aspartate. Both Go6976, the selective inhibitor of Ca2+ -sensitive PKC,, ,I/II, and ,, and MP-20-28, a cell permeable pseudosubstrate inhibitory peptide of PKC, and ,I/II, reduced the effects of ATP on d -[3H]aspartate release by ,45,55%. Similar results were obtained with a mixture of siRNAs targeting rat PKC, and ,I. Surprisingly, down-regulation of individual , and ,I PKC isozymes by siRNA was completely ineffective. These data suggest that ATP regulates VRAC activity and volume-sensitive excitatory amino acid release via cooperative activation of PKC, and ,I. [source]

    Conventional protein kinase C isoforms mediate neuroprotection induced by phorbol ester and estrogen

    JOURNAL OF NEUROCHEMISTRY, Issue 1 2006
    Myriam Cordey
    Abstract Rapid signal transduction pathways play a prominent role in mediating neuroprotective actions of estrogen in the CNS. We have previously shown that estrogen-induced neuroprotection of primary cerebrocortical neurons from ,-amyloid peptide (A,) toxicity depends on activation of protein kinase C (PKC). PKC activation with phorbol-12-myristate-13-acetate (PMA) also provides neuroprotection in this paradigm. Because the PKC family includes several isoforms that have opposing roles in regulating cell survival, we sought to identify which PKC isoforms contribute to neuroprotection induced by PMA and estrogen. We detected protein expression of multiple PKC isoforms in primary neuron cultures, including conventional (,, ,I, ,II), novel (,, ,, ,) and atypical (,, ,/,) PKC. Using a panel of isoform-specific peptide inhibitors and activators, we find that novel and atypical PKC isoforms do not participate in the mechanism of either PMA or estrogen neuroprotection. In contrast, a selective peptide activator of conventional PKC isoforms provides dose-dependent neuroprotection against A, toxicity. In addition, peptide inhibitors of conventional, ,I, or ,II PKC isoforms significantly reduce protection afforded by PMA or 17,-estradiol. Taken together, these data provide evidence that conventional PKC isoforms mediate phorbol ester and estrogen neuroprotection of cultured neurons challenged by A, toxicity. [source]

    Quantitative proteome analysis of detergent-resistant membranes identifies the differential regulation of protein kinase C isoforms in apoptotic T cells

    PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 15 2010
    Therese Solstad
    Abstract Several lines of evidence suggest that detergent-resistant membranes (DRMs) (also known as lipid rafts and glycosphingolipid-enriched microdomains) may have a role in signaling pathways of apoptosis. Here, we developed a method that combines DRMs isolation and methanol/chloroform extraction with stable isotope labeling with amino acids in cell culture-based quantitative proteome analysis of DRMs from control and cisplatin-induced apoptotic Jurkat T cells. This approach enabled us to enrich proteins with a pivotal role in cell signaling of which several were found with increased or decreased amounts in DRMs upon induction of apoptosis. Specifically, we show that three isoforms of protein kinase C (PKC) are regulated differently upon apoptosis. Although PKC, which belongs to the group of conventional PKCs is highly up-regulated in DRMs, the levels of two novel PKCs, PKC, and PKC,, are significantly reduced. These alterations/differences in PKC regulation are verified by immunoblotting and confocal microscopy. In addition, a specific enrichment of PKC, in apoptotic blebs and buds is shown. Furthermore, we observe an increased expression of ecto-PKC, as a result of exposure to cisplatin using flow cytometry. Our results demonstrate that in-depth proteomic analysis of DRMs provides a tool to study differential localization and regulation of signaling molecules important in health and disease. [source]

    Role of novel protein kinase C isoforms in Lyme arthritis

    CELLULAR MICROBIOLOGY, Issue 8 2007
    Ok S. Shin
    Summary Inflammation caused by Borrelia burgdorferi infection occurs as a result of induction of pro-inflammatory cytokines from activation of multiple signalling pathways. It has previously been shown that mitogen-activated protein kinase (MAPK) and Janus kinase/signal transducer and activator of transcription signalling pathways are activated by B. burgdorferi in cultured human chondrocytes. Protein kinase C (PKC) signalling pathways are potential candidates that may control these downstream signalling pathways. Here we show that B. burgdorferi infection leads to phosphorylation and activation of novel PKC isoforms (PKC ,, ,, , and ,) in a time-dependent manner. A specific inhibitor of novel PKC isoforms blocked the induction of pro-inflammatory molecules in response to B. burgdorferi infection as did transient transfection of novel PKC dominant-negative plasmids into chondrocytes. B. burgdorferi -induced p38 MAPK phosphorylation was also significantly inhibited by an inhibitor of novel PKC isoforms, suggesting that PKC activation occurs upstream of p38 activation. In vivo, administration of an inhibitor of classical and novel PKC isoforms to C3H/HeN mice infected with B. burgdorferi resulted in significantly reduced ankle inflammation and swelling. In conclusion, these data suggest that novel PKC isoforms are specifically activated by B. burgdorferi infection and this can contribute to the regulation of inflammation in vitro and in vivo. [source]