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A physical and functional link between splicing factors promotes pre-mRNA 3' end processing.

Millevoi S, Decorsière A, Loulergue C, Iacovoni J, Bernat S, Antoniou M, Vagner S - Nucleic Acids Res. (2009)

Bottom Line: We identify PTB as the protein factor whose binding to the human beta-globin (HBB) 3' UTR is abrogated by a 3' end processing-inactivating mutation.We show that PTB promotes both in vitro 3' end cleavage and polyadenylation and recruits directly the splicing factor hnRNP H to G-rich sequences associated with several pA signals.Therefore, our results provide evidence of a concerted regulation of pA signal recognition by splicing factors bound to auxiliary polyadenylation sequence elements.

View Article: PubMed Central - PubMed

Affiliation: INSERM, U563, Toulouse, Université de Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan, Toulouse, F-31300, France. stefania.millevoi@inserm.fr

ABSTRACT
Polypyrimidine tract-binding protein (PTB) is a splicing regulator that also plays a positive role in pre-mRNA 3' end processing when bound upstream of the polyadenylation signal (pA signal). Here, we address the mechanism of PTB stimulatory function in mRNA 3' end formation. We identify PTB as the protein factor whose binding to the human beta-globin (HBB) 3' UTR is abrogated by a 3' end processing-inactivating mutation. We show that PTB promotes both in vitro 3' end cleavage and polyadenylation and recruits directly the splicing factor hnRNP H to G-rich sequences associated with several pA signals. Increased binding of hnRNP H results in stimulation of polyadenylation through a direct interaction with poly(A) polymerase. Therefore, our results provide evidence of a concerted regulation of pA signal recognition by splicing factors bound to auxiliary polyadenylation sequence elements.

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Eukaryotic conservation of the PTB-bound pyrimidine-rich element within the HBB 3′ UTR as demonstrated by multiple sequence alignment.
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Figure 7: Eukaryotic conservation of the PTB-bound pyrimidine-rich element within the HBB 3′ UTR as demonstrated by multiple sequence alignment.

Mentions: Our results highlight the importance of the PYR2 element for efficient HBB pre-mRNA 3′ end processing. The term+6 β-thalassemia causing mutation within this element reduces both the binding of PTB and 3′ end processing efficiency. A sequence alignment of the 3′ ends of vertebrate HBB genes revealed that the nucleotide affected by the β-thalassemia mutation and the sequence surrounding this base are highly conserved among higher vertebrates (Figure 7). The sequence surrounding the mutation is the pyrimidine-rich region (9 pyrimidines out of 10 nucleotides of the most strongly conserved element) with only two pyrimidine transitions. The upstream, conserved element is also positionally preserved. To gain insight into the possible involvement of this sequence in the control of 3′ end formation of other mRNAs, we analyzed if other human mRNAs contain the sequence [C/T]TTTC[C/T]TGCT upstream of the pA signal. We identified 60 genes that contain this element in their pA signal region. Interestingly, 56 out of the 60 identified genes contained at least one GGG downstream/upstream of the pA signal (Supplementary Table S1).Figure 7.


A physical and functional link between splicing factors promotes pre-mRNA 3' end processing.

Millevoi S, Decorsière A, Loulergue C, Iacovoni J, Bernat S, Antoniou M, Vagner S - Nucleic Acids Res. (2009)

Eukaryotic conservation of the PTB-bound pyrimidine-rich element within the HBB 3′ UTR as demonstrated by multiple sequence alignment.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2724285&req=5

Figure 7: Eukaryotic conservation of the PTB-bound pyrimidine-rich element within the HBB 3′ UTR as demonstrated by multiple sequence alignment.
Mentions: Our results highlight the importance of the PYR2 element for efficient HBB pre-mRNA 3′ end processing. The term+6 β-thalassemia causing mutation within this element reduces both the binding of PTB and 3′ end processing efficiency. A sequence alignment of the 3′ ends of vertebrate HBB genes revealed that the nucleotide affected by the β-thalassemia mutation and the sequence surrounding this base are highly conserved among higher vertebrates (Figure 7). The sequence surrounding the mutation is the pyrimidine-rich region (9 pyrimidines out of 10 nucleotides of the most strongly conserved element) with only two pyrimidine transitions. The upstream, conserved element is also positionally preserved. To gain insight into the possible involvement of this sequence in the control of 3′ end formation of other mRNAs, we analyzed if other human mRNAs contain the sequence [C/T]TTTC[C/T]TGCT upstream of the pA signal. We identified 60 genes that contain this element in their pA signal region. Interestingly, 56 out of the 60 identified genes contained at least one GGG downstream/upstream of the pA signal (Supplementary Table S1).Figure 7.

Bottom Line: We identify PTB as the protein factor whose binding to the human beta-globin (HBB) 3' UTR is abrogated by a 3' end processing-inactivating mutation.We show that PTB promotes both in vitro 3' end cleavage and polyadenylation and recruits directly the splicing factor hnRNP H to G-rich sequences associated with several pA signals.Therefore, our results provide evidence of a concerted regulation of pA signal recognition by splicing factors bound to auxiliary polyadenylation sequence elements.

View Article: PubMed Central - PubMed

Affiliation: INSERM, U563, Toulouse, Université de Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan, Toulouse, F-31300, France. stefania.millevoi@inserm.fr

ABSTRACT
Polypyrimidine tract-binding protein (PTB) is a splicing regulator that also plays a positive role in pre-mRNA 3' end processing when bound upstream of the polyadenylation signal (pA signal). Here, we address the mechanism of PTB stimulatory function in mRNA 3' end formation. We identify PTB as the protein factor whose binding to the human beta-globin (HBB) 3' UTR is abrogated by a 3' end processing-inactivating mutation. We show that PTB promotes both in vitro 3' end cleavage and polyadenylation and recruits directly the splicing factor hnRNP H to G-rich sequences associated with several pA signals. Increased binding of hnRNP H results in stimulation of polyadenylation through a direct interaction with poly(A) polymerase. Therefore, our results provide evidence of a concerted regulation of pA signal recognition by splicing factors bound to auxiliary polyadenylation sequence elements.

Show MeSH