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  1. Article ; Online: Protein kinase Calpha: disease regulator and therapeutic target.

    Konopatskaya, Olga / Poole, Alastair W

    Trends in pharmacological sciences

    2009  Volume 31, Issue 1, Page(s) 8–14

    Abstract: Protein kinase Calpha (PKCalpha) is a member of the AGC (which includes PKD, PKG and PKC) family of serine/threonine protein kinases that is widely expressed in mammalian tissues. It is closely related in structure, function and regulation to other ... ...

    Abstract Protein kinase Calpha (PKCalpha) is a member of the AGC (which includes PKD, PKG and PKC) family of serine/threonine protein kinases that is widely expressed in mammalian tissues. It is closely related in structure, function and regulation to other members of the protein kinase C family, but has specific functions within the tissues in which it is expressed. There is substantial recent evidence, from gene knockout studies in particular, that PKCalpha activity regulates cardiac contractility, atherogenesis, cancer and arterial thrombosis. Selective targeting of PKCalpha therefore has potential therapeutic value in a wide variety of disease states, although will be technically complicated by the ubiquitous expression and multiple functions of the molecule.
    MeSH term(s) Animals ; Cardiovascular Diseases/drug therapy ; Cardiovascular Diseases/physiopathology ; Disease Models, Animal ; Drug Delivery Systems ; Humans ; Mice ; Mice, Knockout ; Neoplasms/drug therapy ; Neoplasms/physiopathology ; Protein Kinase C-alpha/drug effects ; Protein Kinase C-alpha/metabolism ; Thrombosis/drug therapy ; Thrombosis/physiopathology
    Chemical Substances Protein Kinase C-alpha (EC 2.7.11.13)
    Language English
    Publishing date 2009-12-05
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 282846-7
    ISSN 1873-3735 ; 0165-6147
    ISSN (online) 1873-3735
    ISSN 0165-6147
    DOI 10.1016/j.tips.2009.10.006
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Protein kinase C mediates platelet secretion and thrombus formation through protein kinase D2.

    Konopatskaya, Olga / Matthews, Sharon A / Harper, Matthew T / Gilio, Karen / Cosemans, Judith M E M / Williams, Christopher M / Navarro, Maria N / Carter, Deborah A / Heemskerk, Johan W M / Leitges, Michael / Cantrell, Doreen / Poole, Alastair W

    Blood

    2011  Volume 118, Issue 2, Page(s) 416–424

    Abstract: Platelets are highly specialized blood cells critically involved in hemostasis and thrombosis. Members of the protein kinase C (PKC) family have established roles in regulating platelet function and thrombosis, but the molecular mechanisms are not ... ...

    Abstract Platelets are highly specialized blood cells critically involved in hemostasis and thrombosis. Members of the protein kinase C (PKC) family have established roles in regulating platelet function and thrombosis, but the molecular mechanisms are not clearly understood. In particular, the conventional PKC isoform, PKCα, is a major regulator of platelet granule secretion, but the molecular pathway from PKCα to secretion is not defined. Protein kinase D (PKD) is a family of 3 kinases activated by PKC, which may represent a step in the PKC signaling pathway to secretion. In the present study, we show that PKD2 is the sole PKD member regulated downstream of PKC in platelets, and that the conventional, but not novel, PKC isoforms provide the upstream signal. Platelets from a gene knock-in mouse in which 2 key phosphorylation sites in PKD2 have been mutated (Ser707Ala/Ser711Ala) show a significant reduction in agonist-induced dense granule secretion, but not in α-granule secretion. This deficiency in dense granule release was responsible for a reduced platelet aggregation and a marked reduction in thrombus formation. Our results show that in the molecular pathway to secretion, PKD2 is a key component of the PKC-mediated pathway to platelet activation and thrombus formation through its selective regulation of dense granule secretion.
    MeSH term(s) Animals ; Blood Platelets/drug effects ; Blood Platelets/enzymology ; Blood Platelets/metabolism ; Female ; Gene Expression Regulation, Enzymologic ; Humans ; Indoles/pharmacology ; Male ; Maleimides/pharmacology ; Mice ; Mice, Knockout ; Platelet Activation/drug effects ; Platelet Activation/genetics ; Platelet Aggregation/drug effects ; Platelet Aggregation/genetics ; Platelet Aggregation/physiology ; Protein Kinase C/antagonists & inhibitors ; Protein Kinase C/genetics ; Protein Kinase C/metabolism ; Protein Kinase C/physiology ; Protein Kinase D2 ; Protein Kinase Inhibitors/pharmacology ; Protein Kinases/genetics ; Protein Kinases/metabolism ; Protein Kinases/physiology ; Secretory Vesicles/drug effects ; Secretory Vesicles/metabolism ; Signal Transduction/drug effects ; Thrombosis/genetics ; Thrombosis/metabolism
    Chemical Substances Indoles ; Maleimides ; Protein Kinase D2 ; Protein Kinase Inhibitors ; ruboxistaurin (721809WQCP) ; Protein Kinases (EC 2.7.-) ; Protein Kinase C (EC 2.7.11.13)
    Language English
    Publishing date 2011-04-28
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 80069-7
    ISSN 1528-0020 ; 0006-4971
    ISSN (online) 1528-0020
    ISSN 0006-4971
    DOI 10.1182/blood-2010-10-312199
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Functional divergence of platelet protein kinase C (PKC) isoforms in thrombus formation on collagen.

    Gilio, Karen / Harper, Matthew T / Cosemans, Judith M E M / Konopatskaya, Olga / Munnix, Imke C A / Prinzen, Lenneke / Leitges, Michael / Liu, Qinghang / Molkentin, Jeffery D / Heemskerk, Johan W M / Poole, Alastair W

    The Journal of biological chemistry

    2010  Volume 285, Issue 30, Page(s) 23410–23419

    Abstract: Arterial thrombosis, a major cause of myocardial infarction and stroke, is initiated by activation of blood platelets by subendothelial collagen. The protein kinase C (PKC) family centrally regulates platelet activation, and it is becoming clear that the ...

    Abstract Arterial thrombosis, a major cause of myocardial infarction and stroke, is initiated by activation of blood platelets by subendothelial collagen. The protein kinase C (PKC) family centrally regulates platelet activation, and it is becoming clear that the individual PKC isoforms play distinct roles, some of which oppose each other. Here, for the first time, we address all four of the major platelet-expressed PKC isoforms, determining their comparative roles in regulating platelet adhesion to collagen and their subsequent activation under physiological flow conditions. Using mouse gene knock-out and pharmacological approaches in human platelets, we show that collagen-dependent alpha-granule secretion and thrombus formation are mediated by the conventional PKC isoforms, PKCalpha and PKCbeta, whereas the novel isoform, PKC, negatively regulates these events. PKCdelta also negatively regulates thrombus formation but not alpha-granule secretion. In addition, we demonstrate for the first time that individual PKC isoforms differentially regulate platelet calcium signaling and exposure of phosphatidylserine under flow. Although platelet deficient in PKCalpha or PKCbeta showed reduced calcium signaling and phosphatidylserine exposure, these responses were enhanced in the absence of PKC. In summary therefore, this direct comparison between individual subtypes of PKC, by standardized methodology under flow conditions, reveals that the four major PKCs expressed in platelets play distinct non-redundant roles, where conventional PKCs promote and novel PKCs inhibit thrombus formation on collagen.
    MeSH term(s) Animals ; Anticoagulants/pharmacology ; Blood Platelets/drug effects ; Blood Platelets/enzymology ; Blood Platelets/metabolism ; Blood Platelets/physiology ; Calcium Signaling/drug effects ; Collagen/pharmacology ; Humans ; Isoenzymes/antagonists & inhibitors ; Isoenzymes/deficiency ; Isoenzymes/metabolism ; Mice ; Platelet Activation/drug effects ; Platelet Membrane Glycoproteins/pharmacology ; Protein Kinase C/antagonists & inhibitors ; Protein Kinase C/deficiency ; Protein Kinase C/metabolism ; Thrombosis/blood ; Thrombosis/chemically induced ; Thrombosis/enzymology ; Thrombosis/physiopathology
    Chemical Substances Anticoagulants ; Isoenzymes ; Platelet Membrane Glycoproteins ; platelet membrane glycoprotein VI ; Collagen (9007-34-5) ; Protein Kinase C (EC 2.7.11.13)
    Language English
    Publishing date 2010-05-17
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1074/jbc.M110.136176
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: PKCalpha regulates platelet granule secretion and thrombus formation in mice.

    Konopatskaya, Olga / Gilio, Karen / Harper, Matthew T / Zhao, Yan / Cosemans, Judith M E M / Karim, Zubair A / Whiteheart, Sidney W / Molkentin, Jeffery D / Verkade, Paul / Watson, Steve P / Heemskerk, Johan W M / Poole, Alastair W

    The Journal of clinical investigation

    2009  Volume 119, Issue 2, Page(s) 399–407

    Abstract: Platelets are central players in atherothrombosis development in coronary artery disease. The PKC family provides important intracellular mechanisms for regulating platelet activity, and platelets express several members of this family, including the ... ...

    Abstract Platelets are central players in atherothrombosis development in coronary artery disease. The PKC family provides important intracellular mechanisms for regulating platelet activity, and platelets express several members of this family, including the classical isoforms PKCalpha and PKCbeta and novel isoforms PKCdelta and PKCtheta. Here, we used a genetic approach to definitively demonstrate the role played by PKCalpha in regulating thrombus formation and platelet function. Thrombus formation in vivo was attenuated in Prkca-/- mice, and PKCalpha was required for thrombus formation in vitro, although this PKC isoform did not regulate platelet adhesion to collagen. The ablation of in vitro thrombus formation in Prkca-/- platelets was rescued by the addition of ADP, consistent with the key mechanistic finding that dense-granule biogenesis and secretion depend upon PKCalpha expression. Furthermore, defective platelet aggregation in response to either collagen-related peptide or thrombin could be overcome by an increase in agonist concentration. Evidence of overt bleeding, including gastrointestinal and tail bleeding, was not seen in Prkca-/- mice. In summary, the effects of PKCalpha ablation on thrombus formation and granule secretion may implicate PKCalpha as a drug target for antithrombotic therapy.
    MeSH term(s) Adenosine Diphosphate/pharmacology ; Animals ; Blood Platelets/metabolism ; Blood Platelets/ultrastructure ; Cytoplasmic Granules/metabolism ; Integrins/physiology ; Mice ; Platelet Aggregation/drug effects ; Protein Kinase C/physiology ; Protein Kinase C beta ; Protein Kinase C-alpha/physiology ; Signal Transduction ; Thrombosis/etiology
    Chemical Substances Integrins ; Adenosine Diphosphate (61D2G4IYVH) ; Prkca protein, mouse (EC 2.7.11.13) ; Protein Kinase C (EC 2.7.11.13) ; Protein Kinase C beta (EC 2.7.11.13) ; Protein Kinase C-alpha (EC 2.7.11.13)
    Language English
    Publishing date 2009-01-19
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 3067-3
    ISSN 1558-8238 ; 0021-9738
    ISSN (online) 1558-8238
    ISSN 0021-9738
    DOI 10.1172/JCI34665
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Expression of pro- and anti-angiogenic isoforms of VEGF is differentially regulated by splicing and growth factors.

    Nowak, Dawid G / Woolard, Jeanette / Amin, Elianna Mohamed / Konopatskaya, Olga / Saleem, Moin A / Churchill, Amanda J / Ladomery, Michael R / Harper, Steven J / Bates, David O

    Journal of cell science

    2008  Volume 121, Issue Pt 20, Page(s) 3487–3495

    Abstract: Vascular endothelial growth factor A (VEGFA; hereafter referred to as VEGF) is a key regulator of physiological and pathological angiogenesis. Two families of VEGF isoforms are generated by alternate splice-site selection in the terminal exon. Proximal ... ...

    Abstract Vascular endothelial growth factor A (VEGFA; hereafter referred to as VEGF) is a key regulator of physiological and pathological angiogenesis. Two families of VEGF isoforms are generated by alternate splice-site selection in the terminal exon. Proximal splice-site selection (PSS) in exon 8 results in pro-angiogenic VEGFxxx isoforms (xxx is the number of amino acids), whereas distal splice-site selection (DSS) results in anti-angiogenic VEGFxxxb isoforms. To investigate control of PSS and DSS, we investigated the regulation of isoform expression by extracellular growth factor administration and intracellular splicing factors. In primary epithelial cells VEGFxxxb formed the majority of VEGF isoforms (74%). IGF1, and TNFalpha treatment favoured PSS (increasing VEGFxxx) whereas TGFbeta1 favoured DSS, increasing VEGFxxxb levels. TGFbeta1 induced DSS selection was prevented by inhibition of p38 MAPK and the Clk/sty (CDC-like kinase, CLK1) splicing factor kinase family, but not ERK1/2. Clk phosphorylates SR protein splicing factors ASF/SF2, SRp40 and SRp55. To determine whether SR splicing factors alter VEGF splicing, they were overexpressed in epithelial cells, and VEGF isoform production assessed. ASF/SF2, and SRp40 both favoured PSS, whereas SRp55 upregulated VEGFxxxb (DSS) isoforms relative to VEGFxxx. SRp55 knockdown reduced expression of VEGF165b. Moreover, SRp55 bound to a 35 nucleotide region of the 3'UTR immediately downstream of the stop codon in exon 8b. These results identify regulation of splicing by growth and splice factors as a key event in determining the relative pro-versus anti-angiogenic expression of VEGF isoforms, and suggest that p38 MAPK-Clk/sty kinases are responsible for the TGFbeta1-induced DSS selection, and identify SRp55 as a key regulatory splice factor.
    MeSH term(s) Alternative Splicing/drug effects ; Alternative Splicing/physiology ; Angiogenesis Inhibitors/biosynthesis ; Cells, Cultured ; Exons/physiology ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Humans ; Insulin-Like Growth Factor I/pharmacology ; Neovascularization, Pathologic/metabolism ; Neovascularization, Physiologic/physiology ; Phosphorylation/physiology ; Protein Isoforms/biosynthesis ; Protein Serine-Threonine Kinases/metabolism ; Protein-Tyrosine Kinases/metabolism ; RNA Splice Sites/physiology ; RNA-Binding Proteins/metabolism ; Transforming Growth Factor beta1/pharmacology ; Tumor Necrosis Factor-alpha/pharmacology ; Vascular Endothelial Growth Factor A/biosynthesis
    Chemical Substances Angiogenesis Inhibitors ; Protein Isoforms ; RNA Splice Sites ; RNA-Binding Proteins ; Transforming Growth Factor beta1 ; Tumor Necrosis Factor-alpha ; VEGFA protein, human ; Vascular Endothelial Growth Factor A ; Insulin-Like Growth Factor I (67763-96-6) ; Clk dual-specificity kinases (EC 2.7.1.-) ; Protein-Tyrosine Kinases (EC 2.7.10.1) ; Protein Serine-Threonine Kinases (EC 2.7.11.1) ; Extracellular Signal-Regulated MAP Kinases (EC 2.7.11.24)
    Language English
    Publishing date 2008-10-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 2993-2
    ISSN 1477-9137 ; 0021-9533
    ISSN (online) 1477-9137
    ISSN 0021-9533
    DOI 10.1242/jcs.016410
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Expression of pro- and anti-angiogenic isoforms of VEGF is differentially regulated by splicing and growth factors

    Nowak, Dawid G / Woolard, Jeanette / Amin, Elianna Mohamed / Konopatskaya, Olga / Saleem, Moin A / Churchill, Amanda J / Ladomery, Michael R / Harper, Steven J / Bates, David O

    Journal of cell science. 2008 Oct. 15, v. 121, no. 20

    2008  

    Abstract: Vascular endothelial growth factor A (VEGFA; hereafter referred to as VEGF) is a key regulator of physiological and pathological angiogenesis. Two families of VEGF isoforms are generated by alternate splice-site selection in the terminal exon. Proximal ... ...

    Abstract Vascular endothelial growth factor A (VEGFA; hereafter referred to as VEGF) is a key regulator of physiological and pathological angiogenesis. Two families of VEGF isoforms are generated by alternate splice-site selection in the terminal exon. Proximal splice-site selection (PSS) in exon 8 results in pro-angiogenic VEGFxxx isoforms (xxx is the number of amino acids), whereas distal splice-site selection (DSS) results in anti-angiogenic VEGFxxxb isoforms. To investigate control of PSS and DSS, we investigated the regulation of isoform expression by extracellular growth factor administration and intracellular splicing factors. In primary epithelial cells VEGFxxxb formed the majority of VEGF isoforms (74%). IGF1, and TNFα treatment favoured PSS (increasing VEGFxxx) whereas TGFβ1 favoured DSS, increasing VEGFxxxb levels. TGFβ1 induced DSS selection was prevented by inhibition of p38 MAPK and the Clk/sty (CDC-like kinase, CLK1) splicing factor kinase family, but not ERK1/2. Clk phosphorylates SR protein splicing factors ASF/SF2, SRp40 and SRp55. To determine whether SR splicing factors alter VEGF splicing, they were overexpressed in epithelial cells, and VEGF isoform production assessed. ASF/SF2, and SRp40 both favoured PSS, whereas SRp55 upregulated VEGFxxxb (DSS) isoforms relative to VEGFxxx. SRp55 knockdown reduced expression of VEGF₁₆₅b. Moreover, SRp55 bound to a 35 nucleotide region of the 3'UTR immediately downstream of the stop codon in exon 8b. These results identify regulation of splicing by growth and splice factors as a key event in determining the relative pro-versus anti-angiogenic expression of VEGF isoforms, and suggest that p38 MAPK-Clk/sty kinases are responsible for the TGFβ1-induced DSS selection, and identify SRp55 as a key regulatory splice factor.
    Language English
    Dates of publication 2008-1015
    Size p. 3487-3495.
    Publishing place The Company of Biologists Limited
    Document type Article
    ZDB-ID 2993-2
    ISSN 1477-9137 ; 0021-9533
    ISSN (online) 1477-9137
    ISSN 0021-9533
    Database NAL-Catalogue (AGRICOLA)

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  7. Article: Functional Divergence of Platelet Protein Kinase C (PKC) Isoforms in Thrombus Formation on Collagen

    Gilio, Karen / Harper, Matthew T / Cosemans, Judith M.E.M / Konopatskaya, Olga / Munnix, Imke C.A / Prinzen, Lenneke / Leitges, Michael / Liu, Qinghang / Molkentin, Jeffery D / Heemskerk, Johan W.M / Poole, Alastair W

    Journal of biological chemistry. 2010 July 23, v. 285, no. 30

    2010  

    Abstract: Arterial thrombosis, a major cause of myocardial infarction and stroke, is initiated by activation of blood platelets by subendothelial collagen. The protein kinase C (PKC) family centrally regulates platelet activation, and it is becoming clear that the ...

    Abstract Arterial thrombosis, a major cause of myocardial infarction and stroke, is initiated by activation of blood platelets by subendothelial collagen. The protein kinase C (PKC) family centrally regulates platelet activation, and it is becoming clear that the individual PKC isoforms play distinct roles, some of which oppose each other. Here, for the first time, we address all four of the major platelet-expressed PKC isoforms, determining their comparative roles in regulating platelet adhesion to collagen and their subsequent activation under physiological flow conditions. Using mouse gene knock-out and pharmacological approaches in human platelets, we show that collagen-dependent α-granule secretion and thrombus formation are mediated by the conventional PKC isoforms, PKCα and PKCβ, whereas the novel isoform, PKC{theta}, negatively regulates these events. PKCδ also negatively regulates thrombus formation but not α-granule secretion. In addition, we demonstrate for the first time that individual PKC isoforms differentially regulate platelet calcium signaling and exposure of phosphatidylserine under flow. Although platelet deficient in PKCα or PKCβ showed reduced calcium signaling and phosphatidylserine exposure, these responses were enhanced in the absence of PKC{theta}. In summary therefore, this direct comparison between individual subtypes of PKC, by standardized methodology under flow conditions, reveals that the four major PKCs expressed in platelets play distinct non-redundant roles, where conventional PKCs promote and novel PKCs inhibit thrombus formation on collagen.
    Language English
    Dates of publication 2010-0723
    Size p. 23410-23419.
    Publishing place American Society for Biochemistry and Molecular Biology
    Document type Article
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    Database NAL-Catalogue (AGRICOLA)

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