Abstract
Aim of the present study was to elucidate the regulation of the mitogen activated protein (MAP) kinase cascades as well as the cross-talk between the various MAP kinase isoforms (ERK1/2, SAPK and p38) after stimulation of vascular smooth muscle cells (VSMC) with low density lipoprotein (LDL), 100 microg/ml or lysophosphatidic acid (LPA), 5 microg/ml. Furthermore, the role of the intracellular free Ca(2+) concentration ([Ca(2+)](i)) on the activation of the MAP kinase isoforms as well as on the protein expression of MAP kinase phosphatase (MKP)-1 was investigated. The methods used were Western blot analysis, immunoprecipitation and LDL isolation. Involvement of G(i)-proteins on LDL- and LPA-induced activation of the MAP kinase isoforms was examined by treatment of VSMC with pertussis toxin (PTX),100 ng/ml. LDL as well as LPA induced an activation of SAPK and p38 MAP kinase in a PTX-sensitive manner. The ERK1/2, SAPK and p38 MAP kinase activation was a Ca(2+)-dependent process, most likely regulated through modulation of MKP-1 protein expression. Inhibition of ERK1/2 by PD 98059 completely abolished LDL- and LPA-induced activation of SAPK, whereas the activation of p38 MAP kinase was not affected. We conclude, that [Ca(2+)](i) regulates the PTX-sensitive LDL- and LPA-induced stimulation of the MAP kinase cascades, probably via inhibition of the MKP-1 protein expression.
Copyright 2004 S. Karger AG, Basel
MeSH terms
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Animals
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Aorta / cytology
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Aorta / metabolism*
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Calcium Signaling / drug effects
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Cell Cycle Proteins / metabolism*
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Cells, Cultured
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Dual Specificity Phosphatase 1
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Enzyme Activation / drug effects
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Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors
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Extracellular Signal-Regulated MAP Kinases / metabolism
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Flavonoids / pharmacology
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GTP-Binding Protein alpha Subunits, Gi-Go / metabolism
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Gene Expression Regulation, Enzymologic / drug effects
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Humans
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Immediate-Early Proteins / metabolism*
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Isoenzymes / metabolism
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Lipoproteins, LDL / pharmacology*
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Lysophospholipids / pharmacology*
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MAP Kinase Signaling System / drug effects*
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MAP Kinase Signaling System / physiology
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Muscle, Smooth, Vascular / cytology
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Muscle, Smooth, Vascular / metabolism*
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Myocytes, Smooth Muscle / metabolism*
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Pertussis Toxin / pharmacology
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Phosphoprotein Phosphatases / metabolism*
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Phosphorylation / drug effects
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Protein Phosphatase 1
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Protein Tyrosine Phosphatases / metabolism*
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Rats
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Rats, Inbred WKY
Substances
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Cell Cycle Proteins
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Flavonoids
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Immediate-Early Proteins
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Isoenzymes
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Lipoproteins, LDL
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Lysophospholipids
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Pertussis Toxin
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Extracellular Signal-Regulated MAP Kinases
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Phosphoprotein Phosphatases
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Protein Phosphatase 1
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DUSP1 protein, human
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Dual Specificity Phosphatase 1
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Dusp1 protein, rat
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Protein Tyrosine Phosphatases
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GTP-Binding Protein alpha Subunits, Gi-Go
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lysophosphatidic acid
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2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one