scholarly journals Differential effects of hyperphosphorylation on splicing factor SRp55

2003 ◽  
Vol 371 (3) ◽  
pp. 937-945 ◽  
Author(s):  
Ming-Chih LAI ◽  
Ru-Inn LIN ◽  
Woan-Yuh TARN
Keyword(s):  
Rna Polymerase Ii ◽  
Rna Binding ◽  
Sr Proteins ◽  
Binding Activity ◽  
Protein Family ◽  
Nuclear Speckles ◽  
Sr Protein ◽  
Rich Domain ◽  
First Time ◽  
Amino Acid Segment

Members of the serine/arginine-rich (SR) protein family play an important role in both constitutive and regulated splicing of precursor mRNAs. Phosphorylation of the arginine/serine dipeptide-rich domain (RS domain) can modulate the activity and the subcellular localization of SR proteins. However, whether the SR protein family members are individually regulated and how this is achieved remain unclear. In this report we show that 5,6-dichloro-1β-d-ribofuranosyl-benzimidazole (DRB), an inhibitor of RNA polymerase II-dependent transcription, specifically induced hyperphosphorylation of SRp55 but not that of any other SR proteins tested. Hyperphosphorylation of SRp55 occurs at the RS domain and appears to require the RNA-binding activity. Upon DRB treatment, hyperphosphorylated SRp55 relocates to enlarged nuclear speckles. Intriguingly, SRp55 is specifically targeted for degradation by the proteasome upon overexpression of the SR protein kinase Clk/Sty. Although a destabilization signal is mapped within the C-terminal 43-amino acid segment of SRp55, its adjacent lysine/serine-rich RS domain is nevertheless critical for the Clk/Sty-mediated degradation. We report for the first time that SRp55 can be hyperphosphorylated under different circumstances whereby its fate is differentially influenced.

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 Hypophosphorylated SR splicing factors transiently localize around active nucleolar organizing regions in telophase daughter nuclei

2004 ◽  
Vol 167 (1) ◽  
pp. 51-63 ◽  
Author(s):  
Paula A. Bubulya ◽  
Kannanganattu V. Prasanth ◽  
Thomas J. Deerinck ◽  
Daniel Gerlich ◽  
Joel Beaudouin ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Sr Proteins ◽  
Splicing Factors ◽  
Nuclear Speckles ◽  
Sr Protein ◽  
Nucleolar Organizing Regions ◽  
Transcription Sites ◽  
Nuclear Regions ◽  
Rna Polymerase Ii Transcription

Upon completion of mitosis, daughter nuclei assemble all of the organelles necessary for the implementation of nuclear functions. We found that upon entry into daughter nuclei, snRNPs and SR proteins do not immediately colocalize in nuclear speckles. SR proteins accumulated in patches around active nucleolar organizing regions (NORs) that we refer to as NOR-associated patches (NAPs), whereas snRNPs were enriched at other nuclear regions. NAPs formed transiently, persisting for 15–20 min before dissipating as nuclear speckles began to form in G1. In the absence of RNA polymerase II transcription, NAPs increased in size and persisted for at least 2 h, with delayed localization of SR proteins to nuclear speckles. In addition, SR proteins in NAPs are hypophosphorylated, and the SR protein kinase Clk/STY colocalizes with SR proteins in NAPs, suggesting that phosphorylation releases SR proteins from NAPs and their initial target is transcription sites. This work demonstrates a previously unrecognized role of NAPs in splicing factor trafficking and nuclear speckle biogenesis.

Identification of a putative RNA helicase (HRH1), a human homolog of yeast Prp22

1994 ◽  
Vol 14 (11) ◽  
pp. 7611-7620
Author(s):  
Y Ono ◽  
M Ohno ◽  
Y Shimura
Keyword(s):  
Pcr Primers ◽  
Rna Helicase ◽  
Protein Family ◽  
Temperature Sensitive ◽  
Human Homolog ◽  
Rna Helicases ◽  
Sr Protein ◽  
Yeast Saccharomyces Cerevisiae ◽  
Rich Domain

In the budding yeast Saccharomyces cerevisiae, a number of PRP genes known to be involved in pre-mRNA processing have been genetically identified and cloned. Three PRP genes (PRP2, PRP16, and PRP22) were shown to encode putative RNA helicases of the family of proteins with DEAH boxes. However, any such splicing factor containing the helicase motifs in vertebrates has not been identified. To identify human homologs of this family, we designed PCR primers corresponding to the highly conserved region of the DEAH box protein family and successfully amplified five cDNA fragments, using HeLa poly(A)+ RNA as a substrate. One fragment, designated HRH1 (human RNA helicase 1), is highly homologous to Prp22, which was previously shown to be involved in the release of spliced mRNAs from the spliceosomes. Expression of HRH1 in a S. cerevisiae prp22 mutant can partially rescue its temperature-sensitive phenotype. These results strongly suggest that HRH1 is a functional human homolog of the yeast Prp22 protein. Interestingly, HRH1 but not Prp22 contains an arginine- and serine-rich domain (RS domain) which is characteristic of some splicing factors, such as members of the SR protein family. We could show that HRH1 can interact in vitro and in the yeast two-hybrid system with members of the SR protein family through its RS domain. We speculate that HRH1 might be targeted to the spliceosome through this interaction.

scholarly journals Ser7 of RNAPII-CTD facilitates heterochromatin formation by linking ncRNA to RNAi

2017 ◽  
Vol 114 (52) ◽  
pp. E11208-E11217 ◽  
Author(s):  
Takuya Kajitani ◽  
Hiroaki Kato ◽  
Yuji Chikashige ◽  
Chihiro Tsutsumi ◽  
Yasushi Hiraoka ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Chromatin Structure ◽  
Molecular Basis ◽  
Rna Binding ◽  
Noncoding Rnas ◽  
Transcriptional Silencing ◽  
Binding Activity ◽  
Dependent Manner ◽  
Heterochromatin Formation ◽  
A Subunit

Some long noncoding RNAs (ncRNAs) transcribed by RNA polymerase II (RNAPII) are retained on chromatin, where they regulate RNAi and chromatin structure. The molecular basis of this retention remains unknown. We show that in fission yeast serine 7 (Ser7) of the C-terminal domain (CTD) of RNAPII is required for efficient siRNA generation for RNAi-dependent heterochromatin formation. Surprisingly, Ser7 facilitates chromatin retention of nascent heterochromatic RNAs (hRNAs). Chromatin retention of hRNAs and siRNA generation requires both Ser7 and an RNA-binding activity of the chromodomain of Chp1, a subunit of the RNA-induced transcriptional silencing (RITS) complex. Furthermore, RITS associates with RNAPII in a Ser7-dependent manner. We propose that Ser7 promotes cotranscriptional chromatin retention of hRNA by recruiting the RNA-chromatin connector protein Chp1, which facilitates RNAi-dependent heterochromatin formation. Our findings reveal a function of the CTD code: linking ncRNA transcription to RNAi for heterochromatin formation.

scholarly journals A Conserved DrosophilaTransportin-Serine/Arginine-rich (SR) Protein Permits Nuclear Import ofDrosophila SR Protein Splicing Factors and Their Antagonist Repressor Splicing Factor 1

2002 ◽  
Vol 13 (7) ◽  
pp. 2436-2447 ◽  
Author(s):  
Eric Allemand ◽  
Svetlana Dokudovskaya ◽  
Rémy Bordonné ◽  
Jamal Tazi
Keyword(s):  
Nuclear Import ◽  
Direct Interaction ◽  
Sr Proteins ◽  
Splicing Factor ◽  
Nuclear Speckles ◽  
Sr Protein ◽  
Nuclear Factors ◽  
Localization Signal ◽  
Import Receptors ◽  
Splicing Factor 1

Members of the highly conserved serine/arginine-rich (SR) protein family are nuclear factors involved in splicing of metazoan mRNA precursors. In mammals, two nuclear import receptors, transportin (TRN)-SR1 and TRN-SR2, are responsible for targeting SR proteins to the nucleus. Distinctive features in the nuclear localization signal between Drosophila and mammalian SR proteins prompted us to examine the mechanism by whichDrosophila SR proteins and their antagonist repressor splicing factor 1 (RSF1) are imported into nucleus. Herein, we report the identification and characterization of a Drosophilaimportin β-family protein (dTRN-SR), homologous to TRN-SR2, that specifically interacts with both SR proteins and RSF1. dTRN-SR has a broad localization in the cytoplasm and the nucleus, whereas an N-terminal deletion mutant colocalizes with SR proteins in nuclear speckles. Far Western experiments established that the RS domain of SR proteins and the GRS domain of RSF1 are required for the direct interaction with dTRN-SR, an interaction that can be modulated by phosphorylation. Using the yeast model system in which nuclear import of Drosophila SR proteins and RSF1 is impaired, we demonstrate that complementation with dTRN-SR is sufficient to target these proteins to the nucleus. Together, the results imply that the mechanism by which SR proteins are imported to the nucleus is conserved between Drosophila and humans.

The SR protein family of splicing factors: master regulators of gene expression

2008 ◽  
Vol 417 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Jennifer C. Long ◽  
Javier F. Caceres
Keyword(s):  
Gene Expression ◽  
Nuclear Export ◽  
Mrna Translation ◽  
Sr Proteins ◽  
Protein Family ◽  
Sr Protein ◽  
Developmental Defects ◽  
Master Regulators ◽  
Mrna Metabolism ◽  
Nonsense Mediated Mrna Decay

The SR protein family comprises a number of phylogenetically conserved and structurally related proteins with a characteristic domain rich in arginine and serine residues, known as the RS domain. They play significant roles in constitutive pre-mRNA splicing and are also important regulators of alternative splicing. In addition they participate in post-splicing activities, such as mRNA nuclear export, nonsense-mediated mRNA decay and mRNA translation. These wide-ranging roles of SR proteins highlight their importance as pivotal regulators of mRNA metabolism, and if these functions are disrupted, developmental defects or disease may result. Furthermore, animal models have shown a highly specific, non-redundant role for individual SR proteins in the regulation of developmental processes. Here, we will review the current literature to demonstrate how SR proteins are emerging as one of the master regulators of gene expression.

scholarly journals Identification of a putative RNA helicase (HRH1), a human homolog of yeast Prp22.

1994 ◽  
Vol 14 (11) ◽  
pp. 7611-7620 ◽  
Author(s):  
Y Ono ◽  
M Ohno ◽  
Y Shimura
Keyword(s):  
Pcr Primers ◽  
Rna Helicase ◽  
Protein Family ◽  
Temperature Sensitive ◽  
Human Homolog ◽  
Rna Helicases ◽  
Sr Protein ◽  
Yeast Saccharomyces Cerevisiae ◽  
Rich Domain

In the budding yeast Saccharomyces cerevisiae, a number of PRP genes known to be involved in pre-mRNA processing have been genetically identified and cloned. Three PRP genes (PRP2, PRP16, and PRP22) were shown to encode putative RNA helicases of the family of proteins with DEAH boxes. However, any such splicing factor containing the helicase motifs in vertebrates has not been identified. To identify human homologs of this family, we designed PCR primers corresponding to the highly conserved region of the DEAH box protein family and successfully amplified five cDNA fragments, using HeLa poly(A)+ RNA as a substrate. One fragment, designated HRH1 (human RNA helicase 1), is highly homologous to Prp22, which was previously shown to be involved in the release of spliced mRNAs from the spliceosomes. Expression of HRH1 in a S. cerevisiae prp22 mutant can partially rescue its temperature-sensitive phenotype. These results strongly suggest that HRH1 is a functional human homolog of the yeast Prp22 protein. Interestingly, HRH1 but not Prp22 contains an arginine- and serine-rich domain (RS domain) which is characteristic of some splicing factors, such as members of the SR protein family. We could show that HRH1 can interact in vitro and in the yeast two-hybrid system with members of the SR protein family through its RS domain. We speculate that HRH1 might be targeted to the spliceosome through this interaction.

scholarly journals HP1γ binding pre-mRNA at intronic repeats increases splicing fidelity and regulates alternative exon usage

2019 ◽  
Author(s):  
Christophe Rachez ◽  
Rachel Legendre ◽  
Mickaël Costallat ◽  
Hugo Varet ◽  
Jia Yi ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Activity ◽  
Rna Motifs ◽  
Exon Usage ◽  
Cryptic Splice Sites ◽  
The Relationship ◽  
Hp1 Proteins

ABSTRACTHP1 proteins are best known as markers of heterochromatin and gene silencing. Yet, they are also RNA-binding proteins and the HP1γ/Cbx3 family member is present on transcribed genes together with RNA polymerase II, where it regulates co-transcriptional processes such as alternative splicing. To gain insight in the role of the RNA binding activity of HP1γ in transcriptionally active chromatin, we have captured and analyzed RNAs associated with this protein. We find that HP1γ specifically recognizes hexameric RNA motifs and coincidentally transposable elements of the SINE family. As these elements are abundant in introns, while essentially absent from exons, the HP1γ RNA binding activity tethers unspliced pre-mRNA to chromatin via the intronic region and limits the usage of intronic cryptic splice sites. Thus, our data unveil novel determinants in the relationship between chromatin and co-transcriptional splicing.

scholarly journals Mobilization of a splicing factor through a nuclear kinase–kinase complex

2018 ◽  
Vol 475 (3) ◽  
pp. 677-690 ◽  
Author(s):  
Brandon E. Aubol ◽  
Malik M. Keshwani ◽  
Laurent Fattet ◽  
Joseph A. Adams
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
Sr Proteins ◽  
Splicing Factor ◽  
Nuclear Speckles ◽  
Down Regulation ◽  
Sr Protein ◽  
Protein Activation

The splicing of mRNA is dependent on serine-arginine (SR) proteins that are mobilized from membrane-free, nuclear speckles to the nucleoplasm by the Cdc2-like kinases (CLKs). This movement is critical for SR protein-dependent assembly of the macromolecular spliceosome. Although CLK1 facilitates such trafficking through the phosphorylation of serine-proline dipeptides in the prototype SR protein SRSF1, an unrelated enzyme known as SR protein kinase 1 (SRPK1) performs the same function but does not efficiently modify these dipeptides in SRSF1. We now show that the ability of SRPK1 to mobilize SRSF1 from speckles to the nucleoplasm is dependent on active CLK1. Diffusion from speckles is promoted by the formation of an SRPK1–CLK1 complex that facilitates dissociation of SRSF1 from CLK1 and enhances the phosphorylation of several serine-proline dipeptides in this SR protein. Down-regulation of either kinase blocks EGF-stimulated mobilization of nuclear SRSF1. These findings establish a signaling pathway that connects SRPKs to SR protein activation through the associated CLK family of kinases.

scholarly journals Unexpected Role for a Serine/Threonine-Rich Domain in the Candida albicans Iff Protein Family

2011 ◽  
Vol 10 (10) ◽  
pp. 1317-1330 ◽  
Author(s):  
Anita Boisramé ◽  
Amandine Cornu ◽  
Grégory Da Costa ◽  
Mathias L. Richard
Keyword(s):  
Candida Albicans ◽  
Cell Surface ◽  
Protein Localization ◽  
Protein Family ◽  
Content Type ◽  
Rich Domain ◽  
C Terminus ◽  
The Family ◽  
Localization Signal ◽  
First Time

ABSTRACTGlycosylphosphatidylinositol (GPI)-anchored proteins are an important class of cell wall proteins inCandida albicansbecause of their localization and their function, even if more than half of them have no characterized homolog in the databases. In this study, we focused on the IFF protein family, investigating their exposure on the cell surface and the sequences that determine their subcellular localization. Protein localization and surface exposure were monitored by the addition of a V5 tag on all members of the family. The data obtained using the complete proteins showed for Iff3 (or -9), Iff5, Iff6, and Iff8 a covalent linkage to the β-1,6-glucan network but, remarkably, showed that Iff2/Hyr3 was linked through disulfide bridges or NaOH-labile bonds. However, since some proteins of the Iff family were undetectable, we designed chimeric constructions using the last 60 amino acids of these proteins to test the localization signal. These constructions showed a β-1,6-glucan linkage for Iff1/Rbr3, Iff2/Hyr3, Iff4 and Iff7/Hyr4 C-terminal–Iff5 fusion proteins, and a membrane localization for the Iff10/Flo9 C terminus-Iff5 fusion protein. Immunofluorescence analyses coupled to these cell fraction data confirmed the importance of the length of the central serine/threonine-rich region for cell surface exposure. Further analysis of the Iff2/Hyr3 linkage to the cell surface showed for the first time that a serine/threonine central region of a GPI-anchored protein may be responsible for the disulfide and the NaOH bonds to the glucan and glycoproteins network and may also override the signal of the proximal ω site region.

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