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FASEB J. 2010 Nov;24(11):4325-35. doi: 10.1096/fj.10-157362. Epub 2010 Jun 28.

c-Abl mediates high NaCl-induced phosphorylation and activation of the transcription factor TonEBP/OREBP.

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  • 1Laboratory of Kidney and Electrolyte Metabolism, National Heart Lung and Blood Institute, Bethesda, MD 20892-1603, USA.gallazzinim@gmail.com

Abstract

The transcription factor TonEBP/OREBP promotes cell survival during osmotic stress. High NaCl-induced phosphorylation of TonEBP/OREBP at tyrosine-143 was known to be an important factor in increasing its activity in cell culture. We now find that TonEBP/OREBP also is phosphorylated at tyrosine-143 in rat renal inner medulla, dependent on the interstitial osmolality. c-Abl seemed likely to be the kinase that phosphorylates TonEBP/OREBP because Y143 is in a consensus c-Abl phosphorylation site. We now confirm that, as follows. High NaCl increases c-Abl activity. Specific inhibition of c-Abl by imatinib, siRNA, or c-Abl kinase dead drastically reduces high NaCl-induced TonEBP/OREBP activity by reducing its nuclear location and transactivating activity. c-Abl associates with TonEBP/OREBP (coimmunoprecipitation) and phosphorylates TonEBP/OREBP-Y143 both in cell and in vitro. High NaCl-induced activation of ataxia telangiectasia mutated, previously known to contribute to activation of TonEBP/OREBP, depends on c-Abl activity. Thus, c-Abl is the kinase responsible for high NaCl-induced phosphorylation of TonEBP/OREBP-Y143, which contributes to its increased activity.

PMID:
20585028
[PubMed - indexed for MEDLINE]
PMCID:
PMC2974425
Free PMC Article
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