Post-transcriptional regulation of RNase-L expression is mediated by the 3'-untranslated region of its mRNA.
RNase-L mediates critical cellular functions including antiviral, pro-apoptotic, and tumor suppressive activities; accordingly, its expression must be tightly regulated. Little is known about the control of RNASEL expression; therefore, we examined the potential regulatory role of a conserved 3'-untranslated region (3'-UTR) in its mRNA. The 3'-UTR mediated a potent decrease in the stability of RNase-L mRNA, and of a chimeric beta-globin-3'-UTR reporter mRNA. AU-rich elements (AREs) are cis-acting regulatory regions that modulate mRNA stability. Eight AREs were identified in the RNase-L 3'-UTR, and deletion analysis identified positive and negative regulatory regions associated with distinct AREs. In particular, AREs 7 and 8 served a strong positive regulatory function. HuR is an ARE-binding protein that stabilizes ARE-containing mRNAs, and a predicted HuR binding site was identified in the region comprising AREs 7 and 8. Co-transfection of HuR and RNase-L enhanced RNase-L expression and mRNA stability in a manner that was dependent on this 3'-UTR region. Immunoprecipitation demonstrated that RNase-L mRNA associates with a HuR containing complex in intact cells. Activation of endogenous HuR by cell stress, or during myoblast differentiation, increased RNase-L expression, suggesting that RNase-L mRNA is a physiologic target for HuR. HuR-dependent regulation of RNase-L enhanced its antiviral activity demonstrating the functional significance of this regulation. These findings identify a novel mechanism of RNase-L regulation mediated by its 3'-UTR.
Li
Xiao-Ling
XL
University of Maryland, Department of Microbiology and Immunology, Marlene and Stewart Greenebaum Cancer Center, Graduate Program in Molecular Medicine, Baltimore, Maryland 21201, USA.
Andersen
Jesper B
JB
Ezelle
Heather J
HJ
Wilson
Gerald M
GM
Hassel
Bret A
BA
D020413:3' Untranslated Regions; D000954:Antigens, Surface / Q000378:metabolism; D000998:Antiviral Agents / Q000494:pharmacology; D017209:Apoptosis; D001483:Base Sequence; D002454:Cell Differentiation; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; D004722:Endoribonucleases / Q000235:genetics* / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D005914:Globins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D032446:Myoblasts / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism
D020413:3' Untranslated Regions; D000954:Antigens, Surface; D000998:Antiviral Agents; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; C098770:ELAVL1 protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D005914:Globins; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease