High NaCl activates the transcription factor tonicity-responsive enhancer/osmotic response element-binding protein (TonEBP/OREBP), resulting in increased transcription of several protective genes, including the glycine betaine/γ-aminobutyric acid transporter (BGT1). High NaCl damages DNA, and DNA damage activates ataxia telangiectasia mutated (ATM) kinase through autophosphorylation on Ser-1981. TonEBP/OREBP contains ATM consensus phosphorylation sites at Ser-1197, Ser-1247, and Ser-1367. The present studies test whether ATM is involved in activation of TonEBP/OREBP by high NaCl. We find that raising osmolality from 300 to 500 mosmol/kg by adding NaCl activates ATM, as indicated by phosphorylation at Ser-1981. High urea and radiation also activate ATM, but they do not increase TonEBP/OREBP transcriptional activity like high NaCl does. Wortmannin, which inhibits ATM, reduces NaCl-induced TonEBP/OREBP transcriptional activation and BGT1 mRNA increase. Overexpression of wild-type TonEBP/OREBP increases ORE/TonE reporter activity much more than does overexpression of TonEBP/OREBP S1197A, S1247A, or S1367A. In AT cells (which express nonfunctional ATM), TonEBP/OREBP transcriptional and transactivating activity are further increased by expression of wild-type ATM but not of S1981A ATM. TonEBP/OREBP reciprocally coimmunoprecipitates with ATM kinase, demonstrating physical association. Additionally, antibody to ATM kinase supershifts TonEBP/OREBP bound to its cognate ORE/TonE DNA element. In AT cells, wortmannin further decreases high NaCl-induced increase in transcriptional activity, consistent with participation of signaling kinase(s) in addition to ATM. In conclusion, signaling via ATM is necessary for full activation of TonEBP/OREBP by high NaCl, but it is not sufficient
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.