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...

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Bibliographic Details
Published in:The Journal of clinical investigation 1998-11, Vol.102 (10), p.1874-1881
Main Authors: Wojtaszek, P A, Heasley, L E, Berl, T
Format: Article
Language:English
Subjects:
Animals
Calcium-Calmodulin-Dependent Protein Kinases - metabolism
Cells, Cultured
Heat-Shock Proteins - metabolism
Immunoblotting
Kidney Medulla - metabolism
Male
Mitogen-Activated Protein Kinase 9
Mitogen-Activated Protein Kinases
p38 Mitogen-Activated Protein Kinases
Phosphorylation
Protein Kinases - metabolism
Proto-Oncogene Proteins c-jun - metabolism
Rats
Rats, Sprague-Dawley
Water-Electrolyte Balance
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Summary: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.
ISSN:0021-9738
DOI:10.1172/JCI4384