scholarly journals SR proteins: a conserved family of pre-mRNA splicing factors.

1992 ◽  
Vol 6 (5) ◽  
pp. 837-847 ◽  
Author(s):  
A M Zahler ◽  
W S Lane ◽  
J A Stolk ◽  
M B Roth
Keyword(s):  
Sr Proteins ◽  
Mrna Splicing ◽  
Splicing Factors

Multiple roles of arginine/serine-rich splicing factors in RNA processing

2005 ◽  
Vol 33 (3) ◽  
pp. 443-446 ◽  
Author(s):  
J.R. Sanford ◽  
J. Ellis ◽  
J.F. Cáceres
Keyword(s):  
Gene Expression ◽  
Rna Processing ◽  
Rna Metabolism ◽  
Sr Proteins ◽  
Mrna Splicing ◽  
Multiple Roles ◽  
Splicing Factors ◽  
Evolutionarily Conserved ◽  
Initial Characterization

SR proteins (serine- and arginine-rich proteins) are an evolutionarily conserved family consisting of essential pre-mRNA splicing factors. Since their discovery and initial characterization, roles of SR proteins in pre-mRNA splicing and in subsequent steps of post-transcriptional gene expression have expanded significantly. The current hypotheses suggest that SR proteins are multifunctional adaptor molecules that may couple distinct steps of RNA metabolism. In the present study, we will provide an overview of the roles of SR proteins in different steps of post-transcriptional gene expression.

scholarly journals A conserved epitope on a subset of SR proteins defines a larger family of Pre-mRNA splicing factors.

1995 ◽  
Vol 129 (4) ◽  
pp. 899-908 ◽  
Author(s):  
K M Neugebauer ◽  
J A Stolk ◽  
M B Roth
Keyword(s):  
Rna Polymerase Ii ◽  
Active Sites ◽  
Nuclear Extract ◽  
Sr Proteins ◽  
Mrna Splicing ◽  
Splicing Factors ◽  
Structural Element ◽  
Small Nuclear Ribonucleoprotein ◽  
Nuclear Ribonucleoprotein

The removal of introns from eukaryotic pre-mRNA occurs in a large ribonucleoprotein complex called the spliceosome. We have generated a monoclonal antibody (mAb 16H3) against four of the family of six SR proteins, known regulators of splice site selection and spliceosome assembly. In addition to the reactive SR proteins, SRp20, SRp40, SRp55, and SRp75, mAb 16H3 also binds approximately 20 distinct nuclear proteins in human, frog, and Drosophila extracts, whereas yeast do not detectably express the epitope. The antigens are shown to be nuclear, nonnucleolar, and concentrated at active sites of RNA polymerase II transcription which suggests their involvement in pre-mRNA processing. Indeed, most of the reactive proteins observed in nuclear extract are detected in spliceosomes (E and/or B complex) assembled in vitro, including the U1 70K component of the U1 small nuclear ribonucleoprotein particle and both subunits of U2AF. Interestingly, the 16H3 epitope was mapped to a 40-amino acid polypeptide composed almost exclusively of arginine alternating with glutamate and aspartate. All of the identified antigens, including the human homolog of yeast Prp22 (HRH1), contain a similar structural element characterized by arginine alternating with serine, glutamate, and/or aspartate. These results indicate that many more spliceosomal components contain such arginine-rich domains. Because it is conserved among metazoans, we propose that the "alternating arginine" domain recognized by mAb 16H3 may represent a common functional element of pre-mRNA splicing factors.

scholarly journals Serine Phosphorylation of SR Proteins Is Required for Their Recruitment to Sites of Transcription In Vivo

1998 ◽  
Vol 143 (2) ◽  
pp. 297-307 ◽  
Author(s):  
Tom Misteli ◽  
Javier F. Cáceres ◽  
Jade Q. Clement ◽  
Adrian R. Krainer ◽  
Miles F. Wilkinson ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Transcriptional Activation ◽  
Active Sites ◽  
Rna Binding ◽  
Sr Proteins ◽  
Mrna Splicing ◽  
Serine Phosphorylation ◽  
Splicing Factors ◽  
Nuclear Speckles

Expression of most RNA polymerase II transcripts requires the coordinated execution of transcription, splicing, and 3′ processing. We have previously shown that upon transcriptional activation of a gene in vivo, pre-mRNA splicing factors are recruited from nuclear speckles, in which they are concentrated, to sites of transcription (Misteli, T., J.F. Cáceres, and D.L. Spector. 1997. Nature. 387:523–527). This recruitment process appears to spatially coordinate transcription and pre-mRNA splicing within the cell nucleus. Here we have investigated the molecular basis for recruitment by analyzing the recruitment properties of mutant splicing factors. We show that multiple protein domains are required for efficient recruitment of SR proteins from nuclear speckles to nascent RNA. The two types of modular domains found in the splicing factor SF2/ ASF exert distinct functions in this process. In living cells, the RS domain functions in the dissociation of the protein from speckles, and phosphorylation of serine residues in the RS domain is a prerequisite for this event. The RNA binding domains play a role in the association of splicing factors with the target RNA. These observations identify a novel in vivo role for the RS domain of SR proteins and suggest a model in which protein phosphorylation is instrumental for the recruitment of these proteins to active sites of transcription in vivo.

scholarly journals Nuclear Relocalization of the Pre-mRNA Splicing Factor PSF during Apoptosis Involves Hyperphosphorylation, Masking of Antigenic Epitopes, and Changes in Protein Interactions

2001 ◽  
Vol 12 (8) ◽  
pp. 2328-2340 ◽  
Author(s):  
Yaron Shav-Tal ◽  
Michal Cohen ◽  
Smadar Lapter ◽  
Billy Dye ◽  
James G. Patton ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Nuclear Organization ◽  
Sr Proteins ◽  
Mrna Splicing ◽  
Regulatory Proteins ◽  
Splicing Factor ◽  
Splicing Factors ◽  
Nuclear Structures ◽  
Differential Phosphorylation ◽  
Antigenic Epitopes

The spatial nuclear organization of regulatory proteins often reflects their functional state. PSF, a factor essential for pre-mRNA splicing, is visualized by the B92 mAb as discrete nuclear foci, which disappeared during apoptosis. Because this mode of cell death entails protein degradation, it was considered that PSF, which like other splicing factors is sensitive to proteolysis, might be degraded. Nonetheless, during the apoptotic process, PSF remained intact and was N-terminally hyperphosphorylated on serine and threonine residues. Retarded gel migration profiles suggested differential phosphorylation of the molecule in mitosis vs. apoptosis and under-phosphorylation during blockage of cells at G1/S. Experiments with the use of recombinant GFP-tagged PSF provided evidence that in the course of apoptosis the antigenic epitopes of PSF are masked and that PSF reorganizes into globular nuclear structures. In apoptotic cells, PSF dissociated from PTB and bound new partners, including the U1–70K and SR proteins and therefore may acquire new functions.

Organization of transcription and pre-mRNA splicing within the mammalian cell nucleus

1995 ◽  
Vol 53 ◽  
pp. 768-769
Author(s):  
D.L. Spector ◽  
S. Huang ◽  
S. Kaurin
Keyword(s):  
Rna Polymerase Ii ◽  
Cell Nucleus ◽  
Functional Organization ◽  
Mrna Splicing ◽  
Splicing Factors ◽  
Interchromatin Granule Clusters ◽  
Interchromatin Granule ◽  
Nuclear Regions ◽  
Relationship Of ◽  
Perichromatin Fibrils

We have been interested in the organization of RNA polymerase II transcription and pre-mRNA splicing within the cell nucleus. Several models have been proposed for the functional organization of RNA within the eukaryotic nucleus and for the relationship of this organization to the distribution of pre-mRNA splicing factors. One model suggests that RNAs which must be spliced are capable of recruiting splicing factors to the sites of transcription from storage and/or reassembly sites. When one examines the organization of splicing factors in the nucleus in comparison to the sites of chromatin it is clear that splicing factors are not localized in coincidence with heterochromatin (Fig. 1). Instead, they are distributed in a speckled pattern which is composed of both perichromatin fibrils and interchromatin granule clusters. The perichromatin fibrils are distributed on the periphery of heterochromatin and on the periphery of interchromatin granule clusters as well as being diffusely distributed throughout the nucleoplasm. These nuclear regions have been previously shown to represent initial sites of incorporation of 3H-uridine.

scholarly journals Genetic Interactions WithCLF1Identify Additional Pre-mRNA Splicing Factors and a Link Between Activators of Yeast Vesicular Transport and Splicing

Genetics ◽  
2003 ◽  
Vol 164 (3) ◽  
pp. 895-907 ◽  
Author(s):  
Kevin Vincent ◽  
Qiang Wang ◽  
Steven Jay ◽  
Kathryn Hobbs ◽  
Brian C Rymond
Keyword(s):  
Mrna Splicing ◽  
Splicing Factors ◽  
Sequence Information ◽  
Specific Sequence ◽  
Synthetic Lethal ◽  
Growth Defects ◽  
Mrna Maturation ◽  
Assembly Factor ◽  
Gtpase Activation ◽  
Synthetic Growth

AbstractClf1 is a conserved spliceosome assembly factor composed predominately of TPR repeats. Here we show that the TPR elements are not functionally equivalent, with the amino terminus of Clf1 being especially sensitive to change. Deletion and add-back experiments reveal that the splicing defect associated with TPR removal results from the loss of TPR-specific sequence information. Twelve mutants were found that show synthetic growth defects when combined with an allele that lacks TPR2 (i.e., clf1Δ2). The identified genes encode the Mud2, Ntc20, Prp16, Prp17, Prp19, Prp22, and Syf2 splicing factors and four proteins without established contribution to splicing (Bud13, Cet1, Cwc2, and Rds3). Each synthetic lethal with clf1Δ2 (slc) mutant is splicing defective in a wild-type CLF1 background. In addition to the splicing factors, SSD1, BTS1, and BET4 were identified as dosage suppressors of clf1Δ2 or selected slc mutants. These results support Clf1 function through multiple stages of the spliceosome cycle, identify additional genes that promote cellular mRNA maturation, and reveal a link between Rab/Ras GTPase activation and the process of pre-mRNA splicing.

scholarly journals A Functional Interaction between the Carboxy-Terminal Domain of RNA Polymerase II and Pre-mRNA Splicing

1997 ◽  
Vol 136 (1) ◽  
pp. 5-18 ◽  
Author(s):  
Lei Du ◽  
Stephen L. Warren
Keyword(s):  
Rna Polymerase Ii ◽  
Mammalian Cells ◽  
Mrna Splicing ◽  
Splicing Factors ◽  
Functional Interaction ◽  
Carboxy Terminal Domain ◽  
Localization Signal ◽  
Nuclear Domains ◽  
Carboxy Terminal

In the preceding study we found that Sm snRNPs and SerArg (SR) family proteins co-immunoprecipitate with Pol II molecules containing a hyperphosphorylated CTD (Kim et al., 1997). The association between Pol IIo and splicing factors is maintained in the absence of pre-mRNA, and the polymerase need not be transcriptionally engaged (Kim et al., 1997). The latter findings led us to hypothesize that a phosphorylated form of the CTD interacts with pre-mRNA splicing components in vivo. To test this idea, a nested set of CTD-derived proteins was assayed for the ability to alter the nuclear distribution of splicing factors, and to interfere with splicing in vivo. Proteins containing heptapeptides 1-52 (CTD52), 1-32 (CTD32), 1-26 (CTD26), 1-13 (CTD13), 1-6 (CTD6), 1-3 (CTD3), or 1 (CTD1) were expressed in mammalian cells. The CTD-derived proteins become phosphorylated in vivo, and accumulate in the nucleus even though they lack a conventional nuclear localization signal. CTD52 induces a selective reorganization of splicing factors from discrete nuclear domains to the diffuse nucleoplasm, and significantly, it blocks the accumulation of spliced, but not unspliced, human β-globin transcripts. The extent of splicing factor disruption, and the degree of inhibition of splicing, are proportional to the number of heptapeptides added to the protein. The above results indicate a functional interaction between Pol II's CTD and pre-mRNA splicing.

scholarly journals Quantitative Imaging of Pre-mRNA Splicing Factors in Living Cells

2000 ◽  
Vol 11 (2) ◽  
pp. 413-418 ◽  
Author(s):  
Roland Eils ◽  
Daniel Gerlich ◽  
Wolfgang Tvaruskó ◽  
David L. Spector ◽  
Tom Misteli
Keyword(s):  
Quantitative Imaging ◽  
Living Cells ◽  
Mrna Splicing ◽  
Splicing Factors

scholarly journals Demonstration of a dynamic, transcription-dependent organization of pre-mRNA splicing factors in polytene nuclei.

1996 ◽  
Vol 133 (5) ◽  
pp. 929-941 ◽  
Author(s):  
G Baurén ◽  
W Q Jiang ◽  
K Bernholm ◽  
F Gu ◽  
L Wieslander
Keyword(s):  
Mrna Splicing ◽  
Splicing Factor ◽  
Splicing Factors ◽  
Chironomus Tentans ◽  
Transcription Inhibition ◽  
Physiological Conditions ◽  
Active Gene ◽  
U2 Snrnp ◽  
Tight Linkage ◽  
Polytene Nuclei

We describe the dynamic organization of pre-mRNA splicing factors in the intact polytene nuclei of the dipteran Chironomus tentans. The snRNPs and an SR non-snRNP splicing factor are present in excess, mainly distributed throughout the interchromatin. Approximately 10% of the U2 snRNP and an SR non-snRNP splicing factor are associated with the chromosomes, highly enriched in active gene loci where they are bound to RNA. We demonstrate that the splicing factors are specifically recruited to a defined gene upon induction of transcription during physiological conditions. Concomitantly, the splicing factors leave gene loci in which transcription is turned off. We also demonstrated that upon general transcription inhibition, the splicing factors redistribute from active gene loci to the interchromatin. Our findings demonstrate the dynamic intranuclear organization of splicing factors and a tight linkage between transcription and the intranuclear organization of the splicing machinery.

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