Regulation of mitogen-activated protein kinase cascades by low density lipoprotein and lysophosphatidic acid.
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.
Gouni-Berthold
Ioanna
I
Medizinische Universitäts-Poliklinik Bonn.
Seewald
Stefan
S
Hescheler
Jürgen
J
Sachinidis
Agapios
A
D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D054638:Dual Specificity Phosphatase 1; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008246:Lysophospholipids / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D037342:Pertussis Toxin / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY
D018797:Cell Cycle Proteins; D005419:Flavonoids; D017874:Immediate-Early Proteins; D007527:Isoenzymes; D008077:Lipoproteins, LDL; D008246:Lysophospholipids; D037342:Pertussis Toxin; D048049:Extracellular Signal-Regulated MAP Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; C517019:DUSP1 protein, human; D054638:Dual Specificity Phosphatase 1; C517021:Dusp1 protein, rat; D017027:Protein Tyrosine Phosphatases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; C032881:lysophosphatidic acid; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one