AUUUA sequences compromise human insulin-like growth factor binding protein-1 mRNA stability.
The instability of IGFBP-1 mRNA appears to play a role in regulating the expression of the IGFBP-1 gene, the 3' region of which contains five ATTTA sequences. We have studied the implication of these sequences for IGFBP-1 mRNA destabilization. Six plasmids were constructed, containing increasingly shorter lengths of IGFBP-1 cDNA, each with a successive ATTTA sequence deleted from the 3' end. These were stably transfected into two non-IGFBP-1-expressing (cervical carcinoma and neuroblastoma) cell lines. Kinetics studies following inhibition of transcription showed that (1) the half-life of the full-length messenger was 2.80 +/- 0.32 h; (2) deletion of each successive sequence (particularly the second and the fourth) yielded a transcript of increasing stability; and (3) the half-life of the AUUUA-free mRNA was 26.65 +/- 1.65 h. Although the primary source of IGFBP-1 is the liver, our results demonstrate that destabilization of its mRNA is not liver-specific. The ATTTA consensus sequences in the 3' untranslated region of the IGFBP-1 gene therefore provide a posttranscriptional regulation pathway that, combined with transcriptional regulation, may account for the variations in IGFBP-1 expression with developmental stage, nutritional status, and hormonal environment.
Gay
E
E
Croissance, Différenciation et Processus tumoraux, Institut National de la Santé et de la Recherche Médicale, Unité de Recherches U.515, Hôpital Saint Antoine, Paris, France.
Babajko
S
S
D020413:3' Untranslated Regions; D001483:Base Sequence; D016384:Consensus Sequence; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D006207:Half-Life; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000235:genetics*; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D017384:Sequence Deletion; D014162:Transfection; D014407:Tumor Cells, Cultured
D020413:3' Untranslated Regions; D018076:DNA, Complementary; D018970:Insulin-Like Growth Factor Binding Protein 1; D012333:RNA, Messenger