The PITSLRE kinases belong to the large family of cyclin-dependent protein kinases. Their function has been related to cell-cycle regulation, splicing and apoptosis. We have previously shown that the open reading frame of the p110PITSLRE transcript contains an IRES (internal ribosome entry site) that allows the expression of a smaller p58PITSLRE isoform during the G2/M stage of the cell cycle. In the present study we investigated further the role of cis- and trans-acting factors in the regulation of the PITSLRE IRES. Progressive deletion analysis showed that both a purine-rich sequence and a Unr (upstream of N-ras) consensus binding site are essential for PITSLRE IRES activity. In line with these observations, we demonstrate that the PITSLRE IRES interacts with the Unr protein, which is more prominently expressed at the G2/M stage of the cell cycle. We also show that phosphorylation of the α-subunit of the canonical initiation factor eIF-2 is increased at G2/M. Interestingly, phosphorylation of eIF-2α has a permissive effect on the efficiency of both the PITSLRE IRES and the ornithine decarboxylase IRES, two cell cycle-dependent IRESs, in mediating internal initiation of translation, whereas this was not observed with the viral EMCV (encephalomyocarditis virus) and HRV (human rhinovirus) IRESs.
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Research Article|
December 14 2004
Regulation of the cell-cycle-dependent internal ribosome entry site of the PITSLRE protein kinase: roles of Unr (upstream of N-ras) protein and phosphorylated translation initiation factor eIF-2α
Sandrine A. TINTON;
Sandrine A. TINTON
1
1Unit of Molecular Signal Transduction in Inflammation, Department for Molecular Biomedical Research, VIB (Flanders Interuniversity Institute for Biotechnology)–Ghent University, Technologiepark 927, B-9052 Gent-Zwijnaarde, Belgium
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Bert SCHEPENS;
Bert SCHEPENS
1
1Unit of Molecular Signal Transduction in Inflammation, Department for Molecular Biomedical Research, VIB (Flanders Interuniversity Institute for Biotechnology)–Ghent University, Technologiepark 927, B-9052 Gent-Zwijnaarde, Belgium
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Yanik BRUYNOOGHE;
Yanik BRUYNOOGHE
1Unit of Molecular Signal Transduction in Inflammation, Department for Molecular Biomedical Research, VIB (Flanders Interuniversity Institute for Biotechnology)–Ghent University, Technologiepark 927, B-9052 Gent-Zwijnaarde, Belgium
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Rudi BEYAERT;
1Unit of Molecular Signal Transduction in Inflammation, Department for Molecular Biomedical Research, VIB (Flanders Interuniversity Institute for Biotechnology)–Ghent University, Technologiepark 927, B-9052 Gent-Zwijnaarde, Belgium
3To whom correspondence should be addressed (email rudi.beyaert@dmbr.ugent.be).
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Sigrid CORNELIS
Sigrid CORNELIS
2
1Unit of Molecular Signal Transduction in Inflammation, Department for Molecular Biomedical Research, VIB (Flanders Interuniversity Institute for Biotechnology)–Ghent University, Technologiepark 927, B-9052 Gent-Zwijnaarde, Belgium
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Publisher: Portland Press Ltd
Received:
June 08 2004
Revision Received:
August 10 2004
Accepted:
August 26 2004
Accepted Manuscript online:
August 26 2004
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London
2005
Biochem J (2005) 385 (1): 155–163.
Article history
Received:
June 08 2004
Revision Received:
August 10 2004
Accepted:
August 26 2004
Accepted Manuscript online:
August 26 2004
Citation
Sandrine A. TINTON, Bert SCHEPENS, Yanik BRUYNOOGHE, Rudi BEYAERT, Sigrid CORNELIS; Regulation of the cell-cycle-dependent internal ribosome entry site of the PITSLRE protein kinase: roles of Unr (upstream of N-ras) protein and phosphorylated translation initiation factor eIF-2α. Biochem J 1 January 2005; 385 (1): 155–163. doi: https://doi.org/10.1042/BJ20040963
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