The Proximal Region of the 3′-Untranslated Region of Cyclooxygenase-2 is Recognized by a Multimeric Protein Complex Containing HuR, TIA-1, TIAR, and the Heterogeneous Nuclear Ribonucleoprotein U

• Published in: The Journal of biological chemistry Vol. 278; no. 38; pp. 36157 - 36162
• Main Authors: Cok, Steven J., Acton, Stephen J., Morrison, Aubrey R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 19-09-2003
• Subjects: 3' Untranslated Regions; Animals; Antigens, Surface; Base Sequence; Blotting, Western; Cell Nucleus - metabolism; Cells, Cultured; Cyclooxygenase 2; Cytosol - metabolism; ELAV Proteins; ELAV-Like Protein 1; Electrophoresis, Polyacrylamide Gel; Genes, Reporter; Heterogeneous-Nuclear Ribonucleoprotein U - metabolism; Interleukin-1 - metabolism; Isoenzymes - genetics; Isoenzymes - metabolism; Luciferases - metabolism; Male; Membrane Proteins - metabolism; Mice; Molecular Sequence Data; Plasmids - metabolism; Precipitin Tests; Prostaglandin-Endoperoxide Synthases - genetics; Prostaglandin-Endoperoxide Synthases - metabolism; Protein Binding; Proteins; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; RNA-Binding Proteins - metabolism; Subcellular Fractions - metabolism; T-Cell Intracellular Antigen-1; Time Factors; Transfection
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M302547200

Cyclooxygenase-2 (COX-2) is an early response gene induced in renal mesangial cells by interleukin-1β (IL-1β). The 3′-untranslated region (3′-UTR) of COX-2 mRNA plays an important role in IL-1β induction by regulating message stability and translational efficiency. The first 60 nucleotides of the 3′-UTR of COX-2 are highly conserved and contain multiple copies of the regulatory sequence AUUUA. Introduction of the 60-nucleotide sequence into the 3′-UTR of a heterologous reporter gene resulted in a 70% decrease in reporter gene expression. Electrophoretic mobility shift assays (EMSAs) demonstrated that mesangial cell nuclear fractions contain a multimeric protein complex that bound this region of COX-2 mRNA in a sequence-specific manner. We identified four members of the protein-RNA complex as HuR, TIA-1, TIAR, and the heterogeneous nuclear ribonucleoprotein U (hnRNP U). Treatment of mesangial cells with IL-1β caused an increase in cytosolic HuR, which was accompanied by an increase in COX-2 mRNA that co-immunoprecipitated with cytosolic HuR. Therefore, we propose that HuR binds to the proximal region of the 3′-UTR of COX-2 following stimulation by IL-1β and increases the expression of COX-2 mRNA by facilitating its transport out of the nucleus.