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Lookup NU author(s): Professor David Elliott
The human testis has almost as high a frequency of alternative splicing events as brain. While not as extensively studied as brain, a few candidate testis-specific splicing regulator proteins have been identified, including the nuclear RNA binding proteins RBMY and hnRNP G-T, which are germ cell-specific versions of the somatically expressed hnRNP G protein and are highly conserved in mammals. The splicing activator protein Tra2 beta is also highly expressed in the testis and physically interacts with these hnRNP G family proteins. In this study, we identified a novel testis-specific cassette exon TLE4-T within intron 6 of the human transducing-like enhancer of split 4 (TLE4) gene which makes a more transcriptionally repressive TLE4 protein isoform. TLE4-T splicing is normally repressed in somatic cells because of a weak 59 splice site and surrounding splicing-repressive intronic regions. TLE4-T RNA pulls down Tra2 beta and hnRNP G proteins which activate its inclusion. The germ cell-specific RBMY and hnRNP G-T proteins were more efficient in stimulating TLE4-T incorporation than somatically expressed hnRNP G protein. Tra2b bound moderately to TLE4-T RNA, but more strongly to upstream sites to potently activate an alternative 3' splice site normally weakly selected in the testis. Co-expression of Tra2 beta with either hnRNP G-T or RBMY re-established the normal testis physiological splicing pattern of this exon. Although they can directly bind pre-mRNA sequences around the TLE4-T exon, RBMY and hnRNP G-T function as efficient germ cell-specific splicing co-activators of TLE4-T. Our study indicates a delicate balance between the activity of positive and negative splicing regulators combinatorially controls physiological splicing inclusion of exon TLE4-T and leads to modulation of signalling pathways in the testis. In addition, we identified a high-affinity binding site for hnRNP G-T protein, showing it is also a sequence-specific RNA binding protein.
Author(s): Liu Y, Bourgeois CF, Pang S, Kudla M, Dreumont N, Kister L, Sun YH, Stevenin J, Elliott DJ
Publication type: Article
Publication status: Published
Journal: PLoS Genetics
Year: 2009
Volume: 5
Issue: 11
Date deposited: 29/01/2010
ISSN (print): 1553-7390
ISSN (electronic): 1553-7404
Publisher: Public Library of Science
URL: http://dx.doi.org/10.1371/journal.pgen.1000707
DOI: 10.1371/journal.pgen.1000707
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