SB203580 reverses adrenomedullin's effect on proliferation and apoptosis in cultured mesangial cells.
Adrenomedullin is a potent vasodilatory peptide that has a variety of effects in a number of different systems including kidney. In cultured rat glomerular mesangial cells adrenomedullin increases cAMP, decreases proliferation and increases apoptosis. Associated with the anti-proliferative and apoptotic effects, adrenomedullin also causes a decrease in extracellular signal-regulated kinase2 (ERK2) and an increase in cJun N-terminal kinase 1 (JNK1) and P38 mitogen-activated protein kinase (P38 MAPK) activities. The purpose of the present study was to examine the role of P38 MAPK on adrenomedullin-mediated inhibition of [3H]thymidine incorporation (an index of proliferation) and on adrenomedullin-stimulated nucleosome-associated cytoplasmic DNA fragmentation (an index of apoptosis) in mesangial cells, using a selective inhibitor of P38 MAPK, SB203580 [[4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-im idazole], and also to characterize the proximal signal transduction pathways of the three MAPKs in relation to [3H]thymidine incorporation and cytoplasmic DNA fragmentation using a phosphotidyl inositol-3-kinase inhibitor, wortmannin [[1S-(1alpha,6b alpha,9alphabeta,11alpha,11b beta)]-11-(acetyloxy)-1,6b,7,8,9a,10,11,11b-octahydro-1-(methoxyme thyl)-9a,11b-dimethyl-3H-furo[4,3,2-de]indeno[4,5-h]-2-benzopyran-3,6,9- trione]. SB203580 significantly reversed the effects of adrenomedullin on [3H]thymidine incorporation and cytoplasmic DNA fragmentation, and inhibited only P38 MAPK activity. It had no effect on ERK2 and JNK1 activities. Wortmannin, on the other hand, inhibited only adrenomedullin-stimulated cytoplasmic DNA fragmentation and did not affect adrenomedullin-mediated inhibition of [3H]thymidine incorporation. Wortmannin also inhibited adrenomedullin-stimulated P38 MAPK activity without affecting ERK2 and JNK1 activities. These results indicate that: (a) In rat mesangial cells adrenomedullin-mediated inhibition of [3H]thymidine incorporation and stimulation of nucleosome-associated cytoplasmic DNA fragmentation are sensitive to SB203580, and (b) adrenomedullin activates a P38 MAPK through a wortmannin-sensitive kinase. The data using SB203580 suggest an important physiological role for P38 MAPK in rat mesangial cell proliferation and apoptosis.
Parameswaran
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N
Department of Physiology, Michigan State University, East Lansing 48824, USA.
Spielman
W S
WS
Brooks
D P
DP
Nambi
P
P
D053607:Adrenomedullin; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects*; D002478:Cells, Cultured; D053938:DNA Fragmentation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005920:Glomerular Mesangium / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology*; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D010455:Peptides / Q000037:antagonists & inhibitors*; D010770:Phosphotransferases / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013936:Thymidine / Q000378:metabolism; D014665:Vasodilator Agents / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
D004791:Enzyme Inhibitors; D007093:Imidazoles; D010455:Peptides; D011725:Pyridines; D014665:Vasodilator Agents; D053607:Adrenomedullin; D010770:Phosphotransferases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580; D013936:Thymidine