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UNR translation can be driven by an IRES element that is negatively regulated by polypyrimidine tract binding protein.
Nucleic Acids Res. 2005; 33(10):3095-108.NA

Abstract

Upstream of N-ras (Unr) has been described as an internal initiation trans-acting factor (ITAF) in the cap-independent translation of some particular viral and cellular mRNAs. Two factors led us to hypothesize that the UNR 5'-untranslated region (5'-UTR) may contain an internal ribosome entry site (IRES). The first was the requirement for persisting Unr expression under conditions that correlate with cap-independent translation. The other was the observation that the primary UNR transcript contains a 447 nt long 5'-UTR including two upstream AUGs that may restrict translation initiation via cap-dependent ribosome scanning. Here we report that the UNR 5'-UTR allows IRES-dependent translation, as revealed by a dicistronic reporter assay. Various controls ruled out the contribution of leaky scanning, cryptic promoter sequences or RNA processing events to the ability of the UNR 5'-UTR to mediate internal initiation of translation. Ultraviolet cross-linking analysis and RNA affinity chromatography revealed the binding of polypyrimidine tract binding protein (PTB) to the UNR IRES, requiring a pyrimidine-rich region (nucleotides 335-355). Whereas overexpression of PTB in several cell lines inhibited UNR IRES activity and UNR protein expression, depletion of endogenous PTB using RNAi increased UNR IRES activity. Moreover, a mutant version of the UNR IRES lacking the PTB binding site was more efficient at directing IRES-mediated translation. In conclusion, our results demonstrate that translation of the ITAF Unr can itself be regulated by an IRES that is downregulated by PTB.

Authors+Show Affiliations

Department for Molecular Biomedical Research, VIB-Ghent University, Unit of Molecular Signal Transduction in Inflammation B-9052 Gent-Zwijnaarde, Belgium. Sigrid.Cornelis@dmbr.ugent.beNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15928332

Citation

Cornelis, Sigrid, et al. "UNR Translation Can Be Driven By an IRES Element That Is Negatively Regulated By Polypyrimidine Tract Binding Protein." Nucleic Acids Research, vol. 33, no. 10, 2005, pp. 3095-108.
Cornelis S, Tinton SA, Schepens B, et al. UNR translation can be driven by an IRES element that is negatively regulated by polypyrimidine tract binding protein. Nucleic Acids Res. 2005;33(10):3095-108.
Cornelis, S., Tinton, S. A., Schepens, B., Bruynooghe, Y., & Beyaert, R. (2005). UNR translation can be driven by an IRES element that is negatively regulated by polypyrimidine tract binding protein. Nucleic Acids Research, 33(10), 3095-108.
Cornelis S, et al. UNR Translation Can Be Driven By an IRES Element That Is Negatively Regulated By Polypyrimidine Tract Binding Protein. Nucleic Acids Res. 2005;33(10):3095-108. PubMed PMID: 15928332.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - UNR translation can be driven by an IRES element that is negatively regulated by polypyrimidine tract binding protein. AU - Cornelis,Sigrid, AU - Tinton,Sandrine A, AU - Schepens,Bert, AU - Bruynooghe,Yanik, AU - Beyaert,Rudi, Y1 - 2005/05/31/ PY - 2005/6/2/pubmed PY - 2005/6/11/medline PY - 2005/6/2/entrez SP - 3095 EP - 108 JF - Nucleic acids research JO - Nucleic Acids Res VL - 33 IS - 10 N2 - Upstream of N-ras (Unr) has been described as an internal initiation trans-acting factor (ITAF) in the cap-independent translation of some particular viral and cellular mRNAs. Two factors led us to hypothesize that the UNR 5'-untranslated region (5'-UTR) may contain an internal ribosome entry site (IRES). The first was the requirement for persisting Unr expression under conditions that correlate with cap-independent translation. The other was the observation that the primary UNR transcript contains a 447 nt long 5'-UTR including two upstream AUGs that may restrict translation initiation via cap-dependent ribosome scanning. Here we report that the UNR 5'-UTR allows IRES-dependent translation, as revealed by a dicistronic reporter assay. Various controls ruled out the contribution of leaky scanning, cryptic promoter sequences or RNA processing events to the ability of the UNR 5'-UTR to mediate internal initiation of translation. Ultraviolet cross-linking analysis and RNA affinity chromatography revealed the binding of polypyrimidine tract binding protein (PTB) to the UNR IRES, requiring a pyrimidine-rich region (nucleotides 335-355). Whereas overexpression of PTB in several cell lines inhibited UNR IRES activity and UNR protein expression, depletion of endogenous PTB using RNAi increased UNR IRES activity. Moreover, a mutant version of the UNR IRES lacking the PTB binding site was more efficient at directing IRES-mediated translation. In conclusion, our results demonstrate that translation of the ITAF Unr can itself be regulated by an IRES that is downregulated by PTB. SN - 1362-4962 UR - https://www.unboundmedicine.com/medline/citation/15928332/UNR_translation_can_be_driven_by_an_IRES_element_that_is_negatively_regulated_by_polypyrimidine_tract_binding_protein_ L2 - https://academic.oup.com/nar/article-lookup/doi/10.1093/nar/gki611 DB - PRIME DP - Unbound Medicine ER -