Destabilization of interleukin-6 mRNA requires a putative RNA stem-loop structure, an AU-rich element, and the RNA-binding protein AUF1.
Interleukin-6 mRNA is unstable and degraded with a half-life of 30 min. Instability determinants can entirely be attributed to the 3' untranslated region. By grafting segments of this region to stable green fluorescent protein mRNA and subsequent scanning mutagenesis, we have identified two conserved elements, which together account for most of the instability. The first corresponds to a short noncanonical AU-rich element. The other, 80 nucleotides further 5', comprises a sequence predicted to form a stem-loop structure. Neither element alone was sufficient to confer full instability, suggesting that they might cooperate. Overexpression of myc-tagged AUF1 p37 and p42 isoforms as well as suppression of endogenous AUF1 by RNA interference stabilized interleukin-6 mRNA. Both effects required the AU-rich instability element. Similarly, the proteasome inhibitor MG132 stabilized interleukin-6 mRNA probably through an increase of AUF1 levels. The mRNA coimmunoprecipitated specifically with myc-tagged AUF1 p37 and p42 in cell extracts but only when the AU-rich instability element was present. These results indicate that AUF1 binds to the AU-rich element in vivo and promotes IL-6 mRNA degradation.
Paschoud
Serge
S
Swiss Institute for Experimental Cancer Research, Genetics Unit, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland. lukas.kuehn@isrec.ch.
Dogar
Afzal M
AM
Kuntz
Catherine
C
Grisoni-Neupert
Barbara
B
Richman
Larry
L
Kühn
Lukas C
LC
D020413:3' Untranslated Regions; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002522:Chlorocebus aethiops; D049452:Green Fluorescent Proteins / Q000235:genetics; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D / Q000235:genetics* / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017354:Point Mutation; D046988:Proteasome Endopeptidase Complex / Q000235:genetics; D012313:RNA / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D012689:Sequence Homology, Nucleic Acid
D020413:3' Untranslated Regions; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D015850:Interleukin-6; D049452:Green Fluorescent Proteins; D012313:RNA; D046988:Proteasome Endopeptidase Complex