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Lowering NaCl accelerates degradation of TonEBP/OREBP mRNA
Author(s) -
Izumi Yuiricho,
Gallazzini Morgan,
Ferraris Joan D,
Burg Maurice B
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.817.6
Subject(s) - messenger rna , tonicity , osmotic concentration , chemistry , hek 293 cells , microbiology and biotechnology , andrology , transcription (linguistics) , endocrinology , medicine , biology , gene , biochemistry , linguistics , philosophy
Not only does hypertonicity increase the mRNA and protein abundance of the osmoprotective transcription factor, TonEBP/OREBP, but hypotonicity decreases them. The mechanism of the hypotonicity‐induced decrease is poorly understood. We examined this question by measuring the time course of tonicity‐induced increases and decreases of TonEBP/OREBP mRNA abundance, using real time RT‐PCR of extracts from HEK293 cells. Acute increase of osmolality from 300 to 500 mosmol/kg raises TonEBP/OREBP mRNA by a maximum of 2.8‐fold within 8 hours, and it remains 1.7‐fold higher after the cells are adapted to 500 mosmol/kg through several passages. The half life of TonEBP/OREBP mRNA (measured after addition of actinomycin D) is 24 hr both in HEK293 cells adapted to 500 mosmol/kg and in cells left at 300 mosmol/kg. However, decreasing osmolality from 500 to 300 mosmol/kg lowers TonEBP/OREBP mRNA abundance by 60% within 4 hours, which is much too rapid to be explained by decreased transcription alone. We conclude that lowering NaCl accelerates degradation of TonEBP/OREBP mRNA, reducing the time for adaptation to the new condition. Supported by IRP NHLBI