Abstract
Sclerosis and increased matrix expression in diabetes are mediated by glucose-induced transforming growth factor (TGF)-beta1 expression. The intracellular effects of high glucose occur at least in part by way of protein kinase C (PKC). We previously described a role for PKC-alpha in glucose-induced permeability. We now investigated the hypothesis that glucose-induced expression of TGF-beta1 and its receptors (TGF-beta-R1 and -R2) are mediated by activation of this PKC isoform. TGF-beta1 and TGF-beta-R expressions were determined in vascular smooth muscle cells (VSMCs) by immunocytochemistry and Western blotting. PKC isoforms were assessed by confocal microscopy. PKC isoforms were inhibited with antisense oligodeoxynucleotides. PKC-alpha was upregulated by overexpression or microinjection. High glucose (20 mmol/L) increased VSMC TGF-beta1 and TGF-beta-R1 expression but not TGF-beta-R2 expression. PKC inhibitors and specific PKC-alpha downregulation by antisense treatment prevented this effect, whereas antisense treatment against PKC-beta, -epsilon, and -zeta had no influence. PKC-alpha overexpression increased TGF-beta1 and TGF-beta-R1 expression but not TGF-beta-R2 expression. PKC-alpha microinjection into individual VSMCs also increased TGF-beta1 and TGF-beta-R immunofluorescence. Last, VSMCs from PKC-alpha-deficient mice did not respond to high glucose compared with VSMCs from wild-type mice. We propose that high glucose-induced TGF-beta1 and TGF-beta-R1 expression is mediated by PKC-alpha. Our findings suggest an autocrine feedback mechanism and a possible role for PKC-alpha in diabetic vascular disease.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Activin Receptors, Type I / genetics*
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Activin Receptors, Type I / metabolism
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Animals
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Blotting, Western
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Cells, Cultured
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Dose-Response Relationship, Drug
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Enzyme Inhibitors / pharmacology
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Fluorescent Antibody Technique
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Gene Expression Regulation / drug effects
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Glucose / pharmacology*
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Green Fluorescent Proteins
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Luminescent Proteins / genetics
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Luminescent Proteins / metabolism
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Microscopy, Confocal
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Muscle, Smooth, Vascular / cytology
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Muscle, Smooth, Vascular / drug effects*
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Muscle, Smooth, Vascular / metabolism
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Naphthalenes / pharmacology
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Oligonucleotides, Antisense / genetics
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Oligonucleotides, Antisense / pharmacology
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Protein Kinase C / antagonists & inhibitors
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Protein Kinase C / genetics
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Protein Kinase C / metabolism*
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Protein Kinase C-alpha
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Protein Serine-Threonine Kinases
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Rats
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Receptor, Transforming Growth Factor-beta Type I
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Receptors, Transforming Growth Factor beta / genetics*
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Receptors, Transforming Growth Factor beta / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Reverse Transcriptase Polymerase Chain Reaction
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Staurosporine / pharmacology
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Time Factors
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Transforming Growth Factor beta / genetics*
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Transforming Growth Factor beta / metabolism
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Transforming Growth Factor beta1
Substances
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Enzyme Inhibitors
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Luminescent Proteins
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Naphthalenes
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Oligonucleotides, Antisense
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Receptors, Transforming Growth Factor beta
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Recombinant Fusion Proteins
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Tgfb1 protein, rat
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Transforming Growth Factor beta
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Transforming Growth Factor beta1
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calphostin complex
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Green Fluorescent Proteins
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Protein Serine-Threonine Kinases
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Protein Kinase C
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Protein Kinase C-alpha
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Activin Receptors, Type I
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Receptor, Transforming Growth Factor-beta Type I
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Tgfbr1 protein, rat
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Staurosporine
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Glucose