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NFAT5 attenuates damage in the thick ascending limb (TAL)
Author(s) -
Hao shoujin,
Lou Hongxiang,
Darzynkiewicz Zbigniew,
Ferreri Nicholas R.
Publication year - 2013
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.27.1_supplement.727.6
Subject(s) - gene knockdown , small hairpin rna , apoptosis , chemistry , hypoxia (environmental) , transfection , downregulation and upregulation , andrology , viability assay , microbiology and biotechnology , endocrinology , medicine , biology , biochemistry , gene , organic chemistry , oxygen
We previously showed that NFAT5 and NFAT1 are the major NFAT isoforms expressed in the TAL. A role for these isoforms in the response of the TAL to hypertonic‐ or hypoxia‐induced injury has not been clearly defined. Analysis by qRT‐PCR showed that the relative abundance of NFAT5 mRNA increased approximately two‐fold (p<0.05) in outer medulla when mice were given 1% NaCl in the drinking water for 3 days; NFAT1 mRNA accumulation did not change. NFAT5 protein expression increased in mTAL cells exposed to high NaCl concentration (500 mosm/kg H 2 O), and was reduced when cells were transfected with a lentivirus construct (U6N5‐ex8) targeting NFAT5. mTAL cell viability decreased by approximately 60% when osmolality was increased from 300 to 500 mosmol/kg H 2 O for 48 hr. Transient transfection with an NFAT5 overexpression vector, but not empty vector, markedly improved cell viability. Conversely, the percentage of mTAL cells undergoing apoptosis after exposure to high NaCl for 48 hr increased more than 2‐fold when NFAT5 was knocked down by U6N5‐ex8. Increases in NFAT5 and NFAT1 were observed in TAL tubules after ischemic reperfusion injury. However, shRNA knockdown of NFAT5, but not NFAT1, increased the levels of NGAL and Kim‐1, markers of renal damage. Collectively, the data suggest that NFAT5 is part of an adaptive mechanism that protects the TAL from damage due to hypertonic stress, and also may limit damage induced by hypoxia.