Kinetics and regulation of site-specific endonucleolytic cleavage of human IGF-II mRNAs

• Published in: Nucleic acids research Vol. 29; no. 17; pp. 3477 - 3486
• Main Authors: van Dijk, E L, Sussenbach, J S, Holthuizen, P E
• Format: Journal Article
• Language: English
• Published: England Oxford Publishing Limited (England) 01.09.2001; Oxford University Press
• Subjects: 5' Untranslated Regions - genetics; Animals; Blotting, Northern; Cell Count; Cell Line; DNA Restriction Enzymes - metabolism; Gene Expression Regulation - drug effects; Humans; Insulin-Like Growth Factor II - genetics; Insulin-Like Growth Factor II - metabolism; Kinetics; Luciferases - genetics; Luciferases - metabolism; Plasmids - genetics; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; RNA Stability; RNA, Messenger - genetics; RNA, Messenger - metabolism; Tetracycline - pharmacology; Transcription, Genetic; Tumor Cells, Cultured
• ISSN: 1362-4962; 0305-1048; 1362-4962
• DOI: 10.1093/nar/29.17.3477

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.