Kinetics and regulation of site-specific endonucleolytic cleavage of human IGF-II mRNAs.
Human insulin-like growth factor II (IGF-II) mRNA can be cleaved at a specific site in its 4 kb long 3'-UTR. This yields a stable 3' cleavage product of 1.8 kb consisting of a 3'-UTR and a poly(A) tail and an unstable 5' cleavage product containing the IGF-II coding region. After cleavage, the 5' cleavage product is targeted to rapid degradation and consequently is no longer involved in IGF-II protein synthesis. Cleavage is therefore thought to provide an additional way to control IGF-II gene expression. In this paper the kinetics and the efficiency of cleavage of IGF-II mRNAs are examined. The cleavage efficiency of IGF-II mRNAs carrying four different leaders (L1-L4) is enhanced in the highly structured leaders L1 and L3. Additionally, under standard cell culture conditions cleavage is a slow process that only plays a limited role in destabilisation and translation of the IGF-II mRNAs. However, in human Hep3B cells and CaCo2 cells which express IGF-II endogenously, cleavage is upregulated 3-5-fold at high cell densities. Regulated endonucleolytic cleavage of IGF-II mRNAs is restricted to cells in which IGF-II expression is related to specific cell processes.
van Dijk
E L
EL
University Medical Center Utrecht, Department of Physiological Chemistry, Stratenum, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands.
Sussenbach
J S
JS
Holthuizen
P E
PE
D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D015152:Blotting, Northern; D002452:Cell Count; D002460:Cell Line; D004262:DNA Restriction Enzymes / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013752:Tetracycline / Q000494:pharmacology; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D020121:5' Untranslated Regions; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D007335:Insulin-Like Growth Factor II; D008156:Luciferases; D004262:DNA Restriction Enzymes; D013752:Tetracycline