The RNA-binding protein HuR regulates the expression of cyclooxygenase-2.
The cyclooxygenase-2 (COX-2) gene encodes the inducible prostaglandin synthase enzyme implicated in inflammation, cell growth, and tumorigenesis. Regulation of the COX-2 gene expression at the post-transcriptional level is poorly understood. For example, protein factors that regulate the post-transcriptional mRNA metabolism of COX-2 have not been fully characterized. In this study, we demonstrate that the RNA-binding protein HuR binds to COX-2 mRNA and regulates its expression. We show that there are three binding sites for HuR in the 3'-untranslated region of human COX-2. These sites are located at the following positions in the COX-2 3'-untranslated region: 39-84 nucleotides (nt), 1155-1187 nt, and 1244-1256 nt (hereinafter referred to as Sites I, II and III, respectively). Although all three sites are present in the 4.6-kb COX-2 mRNA, only site I is present in the shorter 2.8-kb isoform. HuR in MDA-MB-231 cell extracts associated with COX-2 mRNA at the identified sites. Further, HuR location in the cytoplasm was induced by serum withdrawal, a stimulus known to induce COX-2 mRNA. Down-regulation of HuR by two independent methods, namely RNA interference as well as antisense RNA expression, significantly attenuated serum withdrawal-induced increase in COX-2 mRNA (both the 4.6- and 2.8-kb isoforms) and protein levels. These data suggest that HuR binding to COX-2 is critical for its post-transcriptional mRNA stabilization.
Sengupta
Sibani
S
Center for Vascular Biology, Department of Physiology, University of Connecticut Health Center, 263 Farmington Avenue, 06030-3501, USA.
Jang
Byeong-Churl
BC
Wu
Ming-Tao
MT
Paik
Ji-Hye
JH
Furneaux
Henry
H
Hla
Timothy
T
D000954:Antigens, Surface; D001483:Base Sequence; D051546:Cyclooxygenase 2; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D014407:Tumor Cells, Cultured
D000954:Antigens, Surface; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; C098770:ELAVL1 protein, human; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases