title: Identification of a novel AU-rich-element-binding protein which is related to AUF1.
abstract: The AU-rich element (ARE) is an important instability determinant for a large number of early-response-gene mRNAs. AREs also mediate the stabilization of certain pro-inflammatory mRNAs, such as tumour necrosis factor (TNF)-alpha and cyclo-oxygenase-2 (COX-2), in response to inflammatory stimuli. To understand how AREs control mRNA stability, it is necessary to identify trans-acting factors. We have purified a new ARE-binding protein and identified it as CArG box-binding factor-A (CBF-A). The amino acid sequence of CBF-A is highly similar to that of the ARE-binding protein AUF1. Recombinant CBF-A bound the COX-2 and TNF-alpha AREs, but not a non-specific control RNA. In contrast, in an electrophoretic-mobility-shift assay (EMSA) of crude RAW 264.7 macrophage-like cell extracts, an antiserum that recognizes both AUF1 and CBF-A failed to supershift complexes formed on the TNF-alpha ARE, but did supershift a complex specific for the COX-2 ARE. CBF-A exists as two isoforms, p37 and p42, that differ by a 47-amino-acid insertion close to the C-terminus. By expressing epitope-tagged isoforms of CBF-A it was shown that the p42 isoform binds the COX-2 ARE in EMSA of crude cell extracts. In a HeLa-cell tetracycline-regulated reporter system, overexpression of the p42 CBF-A isoform resulted in stabilization of a COX-2 ARE reporter mRNA. Epitope-tagged p42 CBF-A expressed in HeLa cells co-immunoprecipitated with endogenous COX-2 mRNA, but not glyceraldehyde-3-phosphate dehydrogenase mRNA, as shown by reverse-transcription PCR. The similarity between CBF-A and AUF1 suggests that CBF-A could be re-named AUF2.
authors.affiliation: Kennedy Institute of Rheumatology Division, Faculty of Medicine, Imperial College of Science, Technology and Medicine, Hammersmith, London W6 8LH, UK. jonathan.dean@ic.ac.uk
authors.forename: Jonathan L E
authors.initials: JL
authors.lastname: Dean
authors.forename: Gareth
authors.initials: G
authors.lastname: Sully
authors.forename: Robin
authors.initials: R
authors.lastname: Wait
authors.forename: Lesley
authors.initials: L
authors.lastname: Rawlinson
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Clark
authors.forename: Jeremy
authors.initials: J
authors.lastname: Saklatvala
mesh_terms: D020413:3' Untranslated Regions; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002845:Chromatography; D002851:Chromatography, High Pressure Liquid; D051546:Cyclooxygenase 2; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D017930:Genes, Reporter; D006367:HeLa Cells; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D013058:Mass Spectrometry; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry*; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013347:Subcellular Fractions / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D004268:DNA-Binding Proteins; C000630986:HNRNPD protein, human; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; C000630987:Hnrpd protein, mouse; D007527:Isoenzymes; D008565:Membrane Proteins; D010455:Peptides; D020033:Protein Isoforms; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; D014409:Tumor Necrosis Factor-alpha; C077048:Hnrnpab protein, mouse; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D012260:Ribonucleases