Evidence that tristetraprolin binds to AU-rich elements and promotes the deadenylation and destabilization of tumor necrosis factor alpha mRNA.
Mice deficient in tristetraprolin (TTP), the prototype of a family of CCCH zinc finger proteins, develop an inflammatory syndrome mediated by excess tumor necrosis factor alpha (TNF-alpha). Macrophages derived from these mice oversecrete TNF-alpha, by a mechanism that involves stabilization of TNF-alpha mRNA, and TTP can bind directly to the AU-rich element (ARE) in TNF-alpha mRNA (E. Carballo, W. S. Lai, and P. J. Blackshear, Science 281:1001-1005, 1998). We show here that TTP binding to the TNF-alpha ARE is dependent upon the integrity of both zinc fingers, since mutation of a single cysteine residue in either zinc finger to arginine severely attenuated the binding of TTP to the TNF-alpha ARE. In intact cells, TTP at low expression levels promoted a decrease in size of the TNF-alpha mRNA as well as a decrease in its amount; at higher expression levels, the shift to a smaller TNF-alpha mRNA size persisted, while the accumulation of this smaller species increased. RNase H experiments indicated that the shift to a smaller size was due to TTP-promoted deadenylation of TNF-alpha mRNA. This CCCH protein is likely to be important in the deadenylation and degradation of TNF-alpha mRNA and perhaps other ARE-containing mRNAs, both in normal physiology and in certain pathological conditions.
D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D049452:Green Fluorescent Proteins; D017874:Immediate-Early Proteins; D007700:Kinetics; D008164:Luminescent Proteins / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D008969:Molecular Sequence Data; D010957:Plasmids; D011233:Precipitin Tests; D011499:Protein Processing, Post-Translational; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism / Q000494:pharmacology*; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D016914:Ribonuclease H / Q000378:metabolism; D014018:Tissue Distribution; D051816:Tristetraprolin; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects*; D016335:Zinc Fingers