Differential regulation of aquaporin-5 and -9 expression in astrocytes by protein kinase A.
Aquaporins (AQPs) transport water through the membranes of numerous tissues, but the molecular mechanisms for regulating water balance in brain are unknown. In this study, we investigated the effects of a protein kinase A (PKA) activator on the expression of AQP4, 5 and 9 in cultured rat astrocytes. Treatment of the cells with dbcAMP caused decreases in AQP5 mRNA and protein and increases in AQP9 mRNA and protein in time- and concentration-dependent manners. However, AQP4 mRNA and protein were not changed by treatment with dbcAMP. The dbcAMP-induced effects on AQP5 and AQP9 mRNAs were inhibited by PKA inhibitors. In addition, pretreating the cells with an inhibitor of protein synthesis, cycloheximide, inhibited the increase in AQP9 mRNA induced by dbcAMP, but not the decrease in AQP5 mRNA. These results suggest that signal transduction via PKA may play important roles in regulating the expression of AQP5 and AQP9, and the effect on AQP9 may be mediated by some factors induced by dbcAMP.
Department of Molecular Neurobiology, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, 467-8601, Nagoya, Japan. naoki@med.nagoya-cu.ac.jp
Naoki
N
Yamamoto
Kazuya
K
Sobue
Masataka
M
Fujita
Hirotada
H
Katsuya
Kiyofumi
K
Asai
D000818:Animals; D000831:Animals, Newborn; D051401:Aquaporin 4; D051402:Aquaporin 5; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology*; D001929:Brain Edema / Q000201:enzymology / Q000235:genetics / Q000503:physiopathology; D003994:Bucladesine; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology*; D048429:Cell Size / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D002490:Central Nervous System / Q000166:cytology / Q000201:enzymology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008565:Membrane Proteins; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000235:genetics*
C496032:Aqp4 protein, rat; C496040:Aqp5 protein, rat; C491637:Aqp9 protein, rat; D051401:Aquaporin 4; D051402:Aquaporin 5; D020346:Aquaporins; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D003994:Bucladesine; D017868:Cyclic AMP-Dependent Protein Kinases