Functional hierarchy of AUUUA motifs in mediating rapid interleukin-3 mRNA decay.
In mast cells, expression of interleukin-3 (IL-3) is induced following IgE-receptor activation via calcium-dependent mRNA stabilization. We performed a mutational analysis of the 8 AUUUA motifs located in the 3'-untranslated region of IL-3 mRNA, and analyzed the effect on mRNA stability in PB-3c mast cells. Similar to endogenous IL-3 mRNA, exogenous IL-3 transcripts had a short half-life and were stabilized following stimulation of calcium influx by ionomycin. Specific mutation of 3 AUUUA motifs had almost the same stabilizing effect as deletion of the entire AU-rich region. Mutating even a single critical motif led to a weak, but significant mRNA stabilization. Ionomycin treatment did not further enhance the expression of mutationally stabilized transcripts. Our data fit a model, where within a cluster of 6 AUUUA motifs, 3 adjacent motifs are required for binding of a factor which mediates rapid IL-3 mRNA decay. Activity of such a factor might be under control of a calcium-dependent pathway.
Institute for Medical Microbiology, University of Basel, Switzerland.
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Stoecklin
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Hahn
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Moroni
D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004252:DNA Mutational Analysis; D007377:Interleukin-3 / Q000235:genetics*; D015759:Ionomycin / Q000494:pharmacology; D008407:Mast Cells / Q000378:metabolism; D051379:Mice; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism*; D017384:Sequence Deletion
D007377:Interleukin-3; D012333:RNA, Messenger; D015759:Ionomycin; D002118:Calcium