Extracellular nucleotides activate the p38-stress-activated protein kinase cascade in glomerular mesangial cells.
1. Extracellular ATP and UTP have been reported to activate a nucleotide receptor (P2Y2-receptor) that mediates arachidonic acid release with subsequent prostaglandin formation, a reaction critically depending on the activity of a cytosolic phospholipase A2. In addition, extracellular nucleotides trigger activation of the classical mitogen-activated protein kinase (MAPK) cascade and cell proliferation as well as of the stress-activated protein kinase (SAPK) cascade. 2. In this study, we report that ATP and UTP are also able to activate the p38-MAPK pathway as measured by phosphorylation of the p38-MAPK and its upstream activators MKK3/6, as well as phosphorylation of the transcription factor ATF2 in a immunocomplex-kinase assay. 3. Time courses reveal that ATP and UTP induce a rapid and transient activation of the p38-MAPK activity with a maximal activation after 5 min of stimulation which declined to control levels over the next 20 min. 4. A series of ATP and UPT analogues were tested for their ability to stimulate p38-MAPK activity. UTP and ATP were very effective analogues to activate p38-MAPK, whereas ADP and gamma-thio-ATP had only moderate activating effects. 2-Methyl-thio-ATP, beta gamma-imido-ATP, AMP, adenosine and UDP had no significant effects of p38-MAPK activity. In addition, the extracellular nucleotide-mediated effect on p38-MAPK was almost completely blocked by 1 mM of suramin, a putative P2-purinoceptor antagonist. 5. In summary, these results demonstrate for the first time that extracellular nucleotides are able to activate the MKK3/6- p38-MAPK cascade most likely via the P2Y2-receptor. Moreover, this finding implies that all three MAPK subtypes are signalling candidates for extracellular nucleotide-stimulated cell responses.
Huwiler
A
A
Zentrum der Pharmakologie, Klinikum der J.W. Goethe-Universität, Frankfurt am Main, Germany.
Wartmann
M
M
van den Bosch
H
H
Pfeilschifter
J
J
D051698:Activating Transcription Factor 2; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002417:Cattle; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000502:physiology; D005920:Glomerular Mesangium / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D007093:Imidazoles / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases; D009711:Nucleotides / Q000494:pharmacology*; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D018048:Receptors, Purinergic P2 / Q000502:physiology; D058473:Receptors, Purinergic P2Y2; D013312:Stress, Physiological / Q000201:enzymology*; D013498:Suramin / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism; D014544:Uridine Triphosphate / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
D051698:Activating Transcription Factor 2; C497107:Atf2 protein, rat; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D007093:Imidazoles; D007527:Isoenzymes; D009711:Nucleotides; C546387:P2ry2 protein, rat; D011725:Pyridines; D018048:Receptors, Purinergic P2; D058473:Receptors, Purinergic P2Y2; D014157:Transcription Factors; D013498:Suramin; D000255:Adenosine Triphosphate; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; C093642:SB 203580; D014544:Uridine Triphosphate