Phosphorylation of HuR by Chk2 regulates SIRT1 expression.
The RNA binding protein HuR regulates the stability of many target mRNAs. Here, we report that HuR associated with the 3' untranslated region of the mRNA encoding the longevity and stress-response protein SIRT1, stabilized the SIRT1 mRNA, and increased SIRT1 expression levels. Unexpectedly, oxidative stress triggered the dissociation of the [HuR-SIRT1 mRNA] complex, in turn promoting SIRT1 mRNA decay, reducing SIRT1 abundance, and lowering cell survival. The cell cycle checkpoint kinase Chk2 was activated by H(2)O(2), interacted with HuR, and was predicted to phosphorylate HuR at residues S88, S100, and T118. Mutation of these residues revealed a complex pattern of HuR binding, with S100 appearing to be important for [HuR-SIRT1 mRNA] dissociation after H(2)O(2). Our findings demonstrate that HuR regulates SIRT1 expression, underscore functional links between the two stress-response proteins, and implicate Chk2 in these processes.
Abdelmohsen
Kotb
K
Laboratory of Cellular and Molecular Biology, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
Pullmann
Rudolf
R
Lal
Ashish
A
Kim
Hyeon Ho
HH
Galban
Stefanie
S
Yang
Xiaoling
X
Blethrow
Justin D
JD
Walker
Mark
M
Shubert
Jonathan
J
Gillespie
David A
DA
Furneaux
Henry
H
Gorospe
Myriam
M
D000954:Antigens, Surface / Q000378:metabolism*; D001483:Base Sequence; D016922:Cellular Senescence / Q000187:drug effects; D064447:Checkpoint Kinase 2; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D005786:Gene Expression Regulation / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008969:Molecular Sequence Data; D018384:Oxidative Stress / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D017354:Point Mutation / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D020871:RNA Stability / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000378:metabolism; D056564:Sirtuin 1; D037761:Sirtuins / Q000235:genetics* / Q000378:metabolism*; D013379:Substrate Specificity / Q000187:drug effects
D000954:Antigens, Surface; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; C098770:ELAVL1 protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D006861:Hydrogen Peroxide; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; D017346:Protein Serine-Threonine Kinases; C447939:SIRT1 protein, human; D056564:Sirtuin 1; D037761:Sirtuins