14-3-3sigma is a p37 AUF1-binding protein that facilitates AUF1 transport and AU-rich mRNA decay.
Short-lived cytokine mRNAs contain an AU-rich destabilizing element (ARE). AUF1 proteins bind the ARE, undergo shuttling, and promote cytoplasmic ARE-mRNA decay through a poorly understood mechanism. We therefore identified AUF1-interacting proteins that may play a role in ARE-mRNA decay. We used mass-spectrometry to identify 14-3-3sigma protein as an AUF1-interacting protein. 14-3-3sigma binds selectively and strongly to p37 AUF1 and to a lesser extent to the p40 isoform, the two isoforms most strongly associated with ARE-mRNA decay, but not to the two larger isoforms, p42 and p45. The 14-3-3sigma interaction site on p37 was mapped to a region found only in the two smaller AUF1 isoforms and which overlaps a putative nuclear localization signal (NLS). Stable overexpression of 14-3-3sigma significantly increased cytoplasmic accumulation of p37 AUF1 and reduced the steady-state level and half-life of a reporter ARE-mRNA. siRNA silencing of AUF1 eliminated the effect of 14-3-3sigma overexpression. 14-3-3sigma therefore binds to p37 AUF1, retains it in the cytoplasm probably by masking its NLS, and enhances rapid turnover of ARE-mRNAs.
He
Cheng
C
Department of Microbiology, New York University School of Medicine, New York, NY, USA.
Schneider
Robert
R
D048948:14-3-3 Proteins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D003593:Cytoplasm / Q000378:metabolism; D006367:HeLa Cells; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D021381:Protein Transport; D012333:RNA, Messenger / Q000378:metabolism*
D048948:14-3-3 Proteins; C000630986:HNRNPD protein, human; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D019913:Nuclear Localization Signals; D020033:Protein Isoforms; D012333:RNA, Messenger