In vivo regulation of MAP kinases in Ratus norvegicus renal papilla by water loading and restriction.
In cultured renal cells, hypertonicity activates multiple mitogen-activated protein kinases (MAPKs) and enhances the expression of heat shock proteins (HSPs). In rats, 24 h water restriction increased mean urinary osmolality (Uosm) from 2, 179+/-153 mOsm/kg to 2,944+/-294 mOsm/kg (P < 0.001) and was associated with significant (P < 0.05) increases in the papillary activity of c-Jun NH2-terminal protein kinase (JNK) by 22%, extracellular signal-regulated protein kinase (ERK) by 49%, and p38 MAPK by 15%. Conversely, 24 h of water-loading (Uosm 473+/-33 mOsm/kg) caused suppression of JNK activity by 43% (P < 0.001), ERK by 39% (P < 0.05), and p38 MAPK by 26% (P < 0.05). No such modulation was observed in the isotonic cortex. c-Jun phosphorylation was decreased in papilla from water-loaded rats by 45% versus controls. Expression of Hsp 110, inducible Hsp 70, and Hsp 25 was greater in the hyperosmotic papilla than the isosmotic cortex but was not affected by the animal's hydration state. In cultured inner medullary collecting duct cells, HSP expression was maximal at 500 mOsm/kg, while activation of JNK continued to increase. We conclude that under basal conditions of hydration, these HSPs are maximally expressed in the hypertonic inner medulla, while the activation of all three members of the MAPK family approaches but is not maximal.
Wojtaszek
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PA
Department of Medicine, University of Colorado School of Medicine, Denver, Colorado 80262, USA.
Heasley
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LE
Berl
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T
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D006360:Heat-Shock Proteins / Q000378:metabolism*; D015151:Immunoblotting; D007679:Kidney Medulla / Q000378:metabolism*; D008297:Male; D048056:Mitogen-Activated Protein Kinase 9; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014882:Water-Electrolyte Balance; D048051:p38 Mitogen-Activated Protein Kinases
D006360:Heat-Shock Proteins; D016755:Proto-Oncogene Proteins c-jun; D011494:Protein Kinases; D048056:Mitogen-Activated Protein Kinase 9; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases