title: High glucose-enhanced mesangial cell extracellular signal-regulated protein kinase activation and alpha1(IV) collagen expression in response to endothelin-1: role of specific protein kinase C isozymes.
abstract: High glucose (HG) stimulates glomerular mesangial cell (MC) expression of extracellular matrix, a process involving protein kinase C (PKC) isozymes and enhanced signaling by autocrine peptides such as endothelin-1 (ET-1). The purpose of this study was to identify the specific PKC isozymes mediating the effects of HG on MC extracellular signal-regulated protein kinase (ERK1/2) signaling and alpha1(IV) collagen expression in response to ET-1. HG (30 mmol/l for 72 h) enhanced ET-1-stimulated alpha1(IV) collagen mRNA expression from 1.2 +/- 0.1-fold to 1.9 +/- 0.2-fold (P < 0.05 vs. normal glucose [NG] + ET-1), and the effect was significantly reduced by Calphostin C or the MEK (mitogen-activated protein kinase kinase) inhibitor PD98059. In transiently transfected MCs, dominant-negative (DN)-PKC-delta, -epsilon, or -zeta inhibited ET-1 activation of ERK1/2. Likewise, downstream of ERK1/2, ET-1 stimulated Elk-1-driven GAL4 luciferase activity to 11 +/- 1-fold (P < 0.002 vs. NG + ET-1) in HG, and DN-PKC-delta, -epsilon, or -zeta attenuated this response to NG levels. HG enhanced ET-1-stimulated intracellular alpha1(IV) collagen protein expression, assessed by confocal immunofluorescence imaging, showed that individual DN-PKC-delta, -epsilon, -zeta, as well as DN-PKC-alpha and -beta, attenuated the response. Thus, HG-enhanced ET-1 stimulation of alpha1(IV) collagen expression requires PKC-delta, -epsilon, and -zeta to act through an ERK1/2-dependent pathway and via PKC-alpha and -beta, which are independent of ERK1/2.
authors.affiliation: Institute of Medical Science, the University Health Network. Department of Medicine, University of Toronto, Toronto, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Hua
authors.forename: H J
authors.initials: HJ
authors.lastname: Goldberg
authors.forename: I G
authors.initials: IG
authors.lastname: Fantus
authors.forename: C I
authors.initials: CI
authors.lastname: Whiteside
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003094:Collagen / Q000235:genetics / Q000378:metabolism*; D024141:Collagen Type IV; D004268:DNA-Binding Proteins; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005799:Genes, Dominant; D005920:Glomerular Mesangium / Q000166:cytology / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology*; D006388:Hemagglutinins / Q000235:genetics; D007527:Isoenzymes / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D016324:Sequence Tagged Sites; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1
chemical_list: D024141:Collagen Type IV; D004268:DNA-Binding Proteins; C494114:Elk1 protein, rat; D019332:Endothelin-1; D006388:Hemagglutinins; D007527:Isoenzymes; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; D003094:Collagen; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D005947:Glucose