Human Tra2 Proteins Are Sequence-Specific Activators of Pre-mRNA Splicing

Abstract

The RNA-binding protein Tra2 is an important regulator of sex determination in Drosophila. Recently, two mammalian Tra2 homologs of unknown function have been described. Here, we show that human Tra2 proteins are present in HeLa cell nuclear extracts and that they bind efficiently and specifically to a previously characterized pre-mRNA splicing enhancer element. Indeed, both purified proteins bound preferentially to RNA sequences containing GAA repeats, characteristic of many enhancer elements. Neither Tra2 protein functioned in constitutive splicing in vitro, but both activated enhancer-dependent splicing in a sequence-specific manner and restored it after inhibition with competitor RNA. Our findings indicate that mammalian Tra2 proteins are sequence-specific splicing activators that likely participate in the control of cell-specific splicing patterns.

Expression levels of hnRNP G and hTra2‐beta1 correlate with opposite outcomes in endometrial cancer biology

“…As it is well known that many alternative splicing factors, including hnRNP G and hTra2-beta1, are shuttling intracellularly between nucleus and cytoplasm, it is of large interest to further investigate the mechanism which influences or actively regulates cellular splicing factors shuttling. Both hnRNP G and hTra2-beta1 are sequence-specific splicing factors 21,25,37 and are potentially capable to exert opposite effects on expression of alternative spliced genes in a concentration-dependent manner. 25 HnRNP G preferentially regulates alternative exons where a AAGU or CC(A/C) containing motif is clustered.…”

“…25,37 A panel of tumor biological important genes are regulated through hTra2-beta1 mediated GAA-rich enhancer-dependent splicing. 21 CD44, ESRa, BRCA1, scr, Her2/neu are such genes regulated by hTra2-beta1, which play important roles especially in hormone-dependent malignancies such as breast and ovarian cancer. 6,23 So far, mechanism of these two factors influencing cancer biology remains unknown.…”

“…[13][14][15][16][17][18][19] HTra2-beta1 is one of the SR-like proteins, acting in a concentration-dependent and sequence-specific manner. [20][21][22] An increasing number of human hormone-dependent cancers including breast and ovarian cancer demonstrated pathologically induced expression levels of hTra2-beta1. 6,23 Yeast twohybrid screens and consecutive functional studies revealed that hnRNP G and hTra2-beta1 interact with each other, 24 and they exert antagonizing effects on alternative splicing with opposite splicing preference on human a s -tropomyosin gene as well as opposite consequences of mRNA processing of dystrophin pseudo-exon in muscle tissue.…”

Combinatorial control of a neuron-specific exon

“…In addition to the 39 splice site and the multiple elements of the downstream enhancer, there is another element affecting splicing of the N1 exon+ This sequence is at the 59 end of the N1 exon itself and includes the element GAGGAAGG+ Similar purine-rich elements act as exonic splicing enhancers in other exons (Lavigueur et al+, 1993;Sun et al+, 1993;Tian & Maniatis, 1993;Staknis & Reed, 1994;Ramchatesingh et al+, 1995;Yeakley et al+, 1996)+ When placed by itself in the test exon, this sequence had only a small effect on splicing+ However, activation of the test exon by an intronic enhancer always increased in the presence of this exonic element (Fig+ 7)+ This was most striking for clone 4-187, containing the triple GGGGGCUG repeat, in 3T3 and HEK293 cells (Fig+ 8)+ With this combination of exonic and intronic elements, splicing increased fourto fivefold over either element alone+ The identification of this N1 exonic element, which was missed in earlier mutagenesis studies of the c-src gene, underscores The combination of exonic and intronic enhancer elements has also been described in the regulation of exon 5 of the cardiac troponin T transcript (Ryan & Cooper, 1996)+ In this case again, the exonic element is a general splicing enhancer, whereas the intronic elements determine the tissue specificity+ The intronic GGGGGCUG element in the src transcript is thought to bind to hnRNPs H and F in vitro (Min et al+, 1997;Chou et al+, 1999), whereas the exonic element is similar to sequences known to bind to the proteins SF2/ASF and Tra-2 (Sun et al+, 1993;Tacke & Manley, 1995;Liu et al+, 1998;Tacke et al+, 1998)+ It is not clear whether the proteins bound to these two RNA elements directly contact each other or instead independently interact with components of the spliceosome to alter their assembly+ It will be interesting to examine the proteins binding to these src regulatory elements to determine their interactions with each other and to look at their effect on the assembly of other splicing factors+…”

Transformer 2β and miR-204 regulate apoptosis through competitive binding to 3′ UTR of BCL2 mRNA

“…1,2 The human TRA2β gene consists of 10 exons and generates five mRNA isoforms (TRA2β1-TRA2β5) through alternative splicing. 3 A functional, full-length Tra2β protein encoded by TRA2β1 mRNA contains two SR domains separated by one RNA recognition motif (RRM).…”