Human RNPS1 and Its Associated Factors: a Versatile Alternative Pre-mRNA Splicing Regulator In Vivo

Abstract

Human RNPS1 was originally purified and characterized as a pre-mRNA splicing activator, and its role in the postsplicing process has also been proposed recently. To search for factors that functionally interact with RNPS1, we performed a yeast two-hybrid screen with a human cDNA library. Four factors were identified: p54 (also called SRp54; a member of the SR protein family), human transformer 2␤ (hTra2␤; an exonic splicing enhancer-binding protein), hLucA (a potential component of U1 snRNP), and pinin (also called DRS and MemA; a protein localized in nuclear speckles). The N-terminal region containing the serine-rich (S) domain, the central RNA recognition motif (RRM), and the C-terminal arginine/serine/proline-rich (RS/P) domain of RNPS1 interact with p54, pinin, and hTra2␤, respectively. Protein-protein binding between RNPS1 and these factors was verified in vitro and in vivo. Overexpression of RNPS1 in HeLa cells induced exon skipping in a model ␤-globin pre-mRNA and a human tra-2␤ pre-mRNA. Coexpression of RNPS1 with p54 cooperatively stimulated exon inclusion in an ATP synthase ␥-subunit pre-mRNA. The RS/P domain and RRM are necessary for the exon-skipping activity, whereas the S domain is important for the cooperative effect with p54. RNPS1 appears to be a versatile factor that regulates alternative splicing of a variety of pre-mRNAs.Most pre-mRNAs in higher eukaryotes complete accurate splicing in the nucleus, as a prerequisite for carrying the correct genetic information to the cytoplasm for translation. Constitutive splicing is highly precise and is sensitive to mutations in critical signal sequences of the pre-mRNA. Indeed, human genetic diseases are often caused by point mutations that lie in 5Ј or 3Ј splice site elements or by creation of new ones at inappropriate locations, which result in splicing defects (reviewed in references 33 and 50). On the other hand, a subset of pre-mRNAs shows sufficient flexibility for alternative potential splice sites to be used, often in a regulated way in response to tissue-specific or developmentally regulated states (reviewed in references 24, 55, and 82). This process, called alternative splicing, is a basic strategy for the regulation of eukaryotic gene expression. An unexpectedly small set of protein-coding genes, at most 30,000 has recently been estimated in the human genome (51, 72, 79). Indeed, a higher prevalence of alternative splicing than earlier estimates is likely responsible for a larger number of, and more complex, protein products (51, 64).Pre-mRNA splicing takes place within a large complex, or spliceosome, which includes the small nuclear ribonucleoprotein particles (snRNPs) U1, U2, U4/U6, and U5, together with a large number of non-snRNP protein factors. Biochemical characterization of the spliceosome, together with genetic studies in fission and budding yeast, predicted that more than 50 proteins are essential for constitutive splicing (reviewed in references 15 and 73). The members of the serine/arginine-rich protein (SR protein) family are wel...

The Interaction between Cap-binding Complex and RNA Export Factor Is Required for Intronless mRNA Export

“…Exon junction complexes (EJCs), which are deposited on mRNAs at specific sites relative to the exon junction as a consequence of splicing, form the basis of this connection (7,8). The EJC consists of four core proteins, eIF4A3 (9 -11), Y14 (7), Magoh (12,13), and MLN51 (14), plus other auxiliary proteins including REF (7), UAP56 (15), RNPS1 (7), SRm160 (7), Pinin (16,17), Acinus L (18), SAP18 (18), and hUpf3 (8,19,20). The recruitment of REF during mRNA biogenesis is thought to be responsible for the increased export of spliced mRNA (21).…”

SR and SR-related proteins redistribute to segregated fibrillar components of nucleoli in a response to DNA damage

“…RNPS1 (a serine-rich splicing coactivator), 47,48 and hSlu7 (human Slu7; a homolog of yeast Slu7 and a second-step splicing factor). 49 These factors did not redistribute to the nucleolar periphery upon all, types of DNA-damaging agents, suggesting a specific class of DNA lesion.…”

Isolation, Sequence Identification and Tissue Expression Distribution of Three Novel Porcine Genes-UBC1, TRA2A and SH21A

“…(Jones et al, 2002). Recent reports described that UBCl is involved in cellular functions TRABA is a sequence-specific RNAbinding protein which participates in the control of pre-mRNA splicing (Sakashita et al, 2004). It also is reported to be involved *Corresponding author: E-mail: liuyg4567@163.com 33 i n t h e sex differentiation in drosophila (Shiraishi et al, 2004).…”