Open AccessPTB Regulates the Processing of a 3′-Terminal Exon by Repressing both Splicing and Polyadenylation
Author(s) -
Caroline Sommer,
Michelle Lesimple,
Agnès Méreau,
Séverine Ménoret,
MarieRose Allo,
Serge Hardy
Publication year - 2005
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.25.21.9595-9607.2005
Subject(s) - biology , exon , minigene , polyadenylation , xenopus , rna splicing , alternative splicing , microbiology and biotechnology , gene knockdown , polypyrimidine tract binding protein , somite , genetics , messenger rna , gene , embryo , rna , embryogenesis
The polypyrimidine tract binding protein (PTB) has been described as a global repressor of regulated exons. To investigate PTB functions in a physiological context, we used a combination of morpholino-mediated knockdown and transgenic overexpression strategies inXenopus laevis embryos. We show that embryonic endoderm and skin deficient in PTB displayed a switch of the α-tropomyosin pre-mRNA 3′ end processing to the somite-specific pattern that results from the utilization of an upstream 3′-terminal exon designed exon 9A9′. Conversely, somitic targeted overexpression of PTB resulted in the repression of the somite-specific exon 9A9′ and a switch towards the nonmuscle pattern. These results validate PTB as a key physiological regulator of the 3′ end processing of the α-tropomyosin pre-mRNA. Moreover, using a minigene strategy in theXenopus oocyte, we show that in addition to repressing the splicing of exon 9A9′, PTB regulates the cleavage/polyadenylation of this 3′-terminal exon.