scholarly journals Interactions between two fission yeast serine/arginine-rich proteins and their modulation by phosphorylation

2002 ◽  
Vol 368 (2) ◽  
pp. 527-534 ◽  
Author(s):  
Zhaohua TANG ◽  
Norbert F. KÄUFER ◽  
Ren-Jang LIN
Keyword(s):  
Alternative Splicing ◽  
Protein Phosphorylation ◽  
Fission Yeast ◽  
Protein Function ◽  
Sr Proteins ◽  
Specific Protein ◽  
Glutathione S Transferase ◽  
Sr Protein ◽  
Random Screen ◽  
Related Proteins

The unexpected low number of genes in the human genome has triggered increasing attention to alternative pre-mRNA splicing, and serine/arginine-rich (SR) proteins have been correlated with the complex alternative splicing that is a characteristic of metazoans. SR proteins interact with RNA and splicing protein factors, and they also undergo reversible phosphorylation, thereby regulating constitutive and alternative splicing in mammals and Drosophila. However, it is not clear whether the features of SR proteins and alternative splicing are present in simple and genetically tractable organisms, such as yeasts. In the present study, we show that the SR-like proteins Srp1 and Srp2, found in the fission yeast Schizosaccharomyces pombe, interact with each other and the interaction is modulated by protein phosphorylation. By using Srp1 as bait in a yeast two-hybrid analysis, we specifically isolated Srp2 from a random screen. This Srp interaction was confirmed by a glutathione-S-transferase pull-down assay. We also found that the Srp1—Srp2 complex was phosphorylated at a reduced efficiency by a fission yeast SR-specific kinase, Dis1-suppression kinase (Dsk1). Conversely, Dsk1-mediated phosphorylation inhibited the formation of the Srp complex. These findings offer the first example in fission yeast for interactions between SR-related proteins and the modulation of the interactions by specific protein phosphorylation, suggesting that a mammalian-like SR protein function may exist in fission yeast.

scholarly journals Dsk1p kinase phosphorylates SR proteins and regulates their cellular localization in fission yeast

2007 ◽  
Vol 405 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Zhaohua Tang ◽  
Amy Tsurumi ◽  
Sarah Alaei ◽  
Christopher Wilson ◽  
Cathleen Chiu ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Fission Yeast ◽  
Cellular Localization ◽  
Sr Proteins ◽  
Regulatory Function ◽  
General Mechanism ◽  
Nuclear Targeting ◽  
Sr Protein ◽  
Eukaryotic Organism

Evolutionarily conserved SR proteins (serine/arginine-rich proteins) are important factors for alternative splicing and their activity is modulated by SRPKs (SR protein-specific kinases). We previously identified Dsk1p (dis1-suppressing protein kinase) as the orthologue of human SRPK1 in fission yeast. In addition to its similarity of gene structure to higher eukaryotes, fission yeast Schizosaccharomyces pombe is a unicellular eukaryotic organism in which alternative splicing takes place. In the present study, we have revealed for the first time that SR proteins, Srp1p and Srp2p, are the in vivo substrates of Dsk1p in S. pombe. Moreover, the cellular localization of the SR proteins and Prp2p splicing factor is dependent on dsk1+: Dsk1p is required for the efficient nuclear localization of Srp2p and Prp2p, while it promotes the cytoplasmic distribution of Srp1p, thereby differentially influencing the destinations of these proteins in the cell. The present study offers the first biochemical and genetic evidence for the in vivo targets of the SRPK1 orthologue, Dsk1p, in S. pombe and the significant correlation between Dsk1p-mediated phosphorylation and the cellular localization of the SR proteins, providing information about the physiological functions of Dsk1p. Furthermore, the results demonstrate that the regulatory function of SRPKs in the nuclear targeting of SR proteins is conserved from fission yeast to human, indicating a general mechanism of reversible phosphorylation to control the activities of SR proteins in RNA metabolism through cellular partitioning.

scholarly journals Akt2 Regulation of Cdc2-Like Kinases (Clk/Sty), Serine/Arginine-Rich (SR) Protein Phosphorylation, and Insulin-Induced Alternative Splicing of PKCβII Messenger Ribonucleic Acid

Endocrinology ◽  
2008 ◽  
Vol 150 (5) ◽  
pp. 2087-2097 ◽  
Author(s):  
Kun Jiang ◽  
Niketa A. Patel ◽  
James E. Watson ◽  
Hercules Apostolatos ◽  
Eden Kleiman ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Protein Phosphorylation ◽  
Kinase Inhibitors ◽  
Sr Proteins ◽  
Null Mouse ◽  
Phosphatidylinositol 3 Kinase ◽  
Sr Protein ◽  
Messenger Ribonucleic Acid ◽  
Extracellular Signals ◽  
Mouse Tissues

Serine/arginine-rich (SR) proteins play essential roles in the constitutive and regulated splicing of precursor mRNAs. Phosphorylation of the arginine/serine dipeptide-rich (RS) domain by SR protein kinases such as Cdc2-like kinases (Clk/Sty) modulates their subcellular localization and activation. However, it remains unclear how these kinases and their target SR proteins are regulated by extracellular signals. Regulation of protein kinase C βII (PKCβII) pre-mRNA alternative splicing via exon inclusion by Akt2, a central kinase in insulin action, involves phosphorylation of SR proteins. Here we showed that Akt2, in response to insulin, resulted in phosphorylation of Clk/Sty, which then altered SR protein phosphorylation in concert with Akt2. Insulin-stimulated PKCβII pre-mRNA splicing was blocked by Clk/Sty and phosphatidylinositol-3-kinase inhibitors, and diabetic Akt2-null mouse tissues had impaired phospho-Clk/Sty, SR protein phosphorylation, and PKCβII expression. Furthermore, we observed that Akt2 phosphorylated several SR proteins distinct from Clk/Sty in response to insulin. Akt2-catalyzed phosphorylation of Clk/Sty and SR proteins revealed a role for both kinases in splicing regulation indicating dual functions for Akt2 in response to insulin in this pathway.

scholarly journals Functional properties of p54, a novel SR protein active in constitutive and alternative splicing.

1996 ◽  
Vol 16 (10) ◽  
pp. 5400-5408 ◽  
Author(s):  
W J Zhang ◽  
J Y Wu
Keyword(s):  
Alternative Splicing ◽  
Splice Site ◽  
Sr Proteins ◽  
Dependent Manner ◽  
Sr Protein ◽  
Protein Protein Interaction ◽  
Small Nuclear Ribonucleoprotein ◽  
S100 Extract ◽  
U2 Auxiliary Factor ◽  
Auxiliary Factor

The p54 protein was previously identified by its reactivity with an autoantiserum. We report here that p54 is a new member of the SR family of splicing factors, as judged from its structural, antigenic, and functional characteristics. Consistent with its identification as an SR protein, p54 can function as a constitutive splicing factor in complementing splicing-deficient HeLa cell S100 extract. However, p54 also shows properties distinct from those of other SR family members, p54 can directly interact with the 65-kDa subunit of U2 auxiliary factor (U2AF65), a protein associated with the 3' splice site. In addition, p54 interacts with other SR proteins but does not interact with the U1 small nuclear ribonucleoprotein U1-70K or the 35-kDa subunit of U2 auxiliary factor (U2AF35). This protein-protein interaction profile is different from those of prototypical SR proteins SC35 and ASF/SF2, both of which interact with U1-70K and U2AF35 but not with U2AF65. p54 promotes the use of the distal 5' splice site in E1A pre-mRNA alternative splicing, while the same site is suppressed by ASF/SF2 and SC35. These findings and the differential tissue distribution of p54 suggest that this novel SR protein may participate in regulation of alternative splicing in a tissue- and substrate-dependent manner.

Abstract 805: Differential Regulation Of Cytokine-induced Alternative Splicing Of The TF Gene By Serine/Arginine Rich Protein Kinases

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Ursula Rauch ◽  
Andreas Eisenreich ◽  
Wolfgang Poller ◽  
Heinz-Peter Schultheiss
Keyword(s):  
Alternative Splicing ◽  
Protein Phosphorylation ◽  
Mrna Expression ◽  
Tissue Factor ◽  
Splice Variant ◽  
Sr Protein ◽  
Phosphorylation State ◽  
Post Induction ◽  
Tnf Α ◽  
Tf Gene

Background: Higher eukaryotes control gene expression and increase protein diversity by alternative splicing of pre-mRNA. The Cdc2-like kinase (Clk) family, DNA topoisomerase I (DNA topo I) or Akt kinase are involved in splicing control by regulating the phosphorylation state of serine/arginine rich (SR) proteins. We recently showed that alternatively spliced human tissue factor (asHTF), a soluble isoform of tissue factor (TF), the primary initiator of coagulation, is expressed in HUVECs in response to inflammatory cytokines. This study investigated the role of Clks, DNA topo I and the PI3K-Pathway in regulation of TF-splicing in TNF-α induced HUVECs. Methods: HUVECs were incubated with inhibitors of Clks, DNA-topo I or PI3K and were then stimulated with TNF-α. The SR protein phosphorylation state was determined 2 min post induction. The full length (fl) TF and asHTF mRNA were assessed 60 min post induction by Real-Time PCR. Proteins were measured 5 and 8 hours after stimulation by Western blots and the cell thrombogenicity was analyzed via a chromogenic assay. Results: TNF-α inceased the mRNA expression of asHTF and flTF in HUVECs. The Clk-inhibitor completely inhibited the TNF-α induced expression of asHTF and reduced flTF by 30 %. Inhibition of DNA topo I increased asHTF expression and reduced the flTF expression. Inhibition of the PI3K/Akt-pathway had no effect on TF mRNA expression. Reduced Clk-inhibition the TF activity by 50 % whereas DNA topo I inhibition significantly decreased the procoagulant TF activity 8 hours post TNF-α induction. The Clk- and DNA-topo I-inhibitors altered the SR-protein phosphorylation pattern post TNF-α-induction. Additionally resulted inhibition of Clks in the generation of a third TF mRNA-splice variant, TF-A. Conclusion: Selective inhibition of Clks or DNA topo I leads to alterations of SR-protein phosphorylation and affects the differential expression of TF isoforms, thereby modulating the thrombogenicity of HUVECs. The inhibition of Clks contributes to the generation of a third TF splice variant. The inhibition of these kinases gives new insights into the regulation of the TF gene splicing process, which may result in new therapeutic strategies for modulating cellular thrombogenicity.

scholarly journals Characterization and comparison of four serine- and arginine-rich (SR) protein kinases

1997 ◽  
Vol 326 (3) ◽  
pp. 693-700 ◽  
Author(s):  
Oliver NAYLER ◽  
Stefan STAMM ◽  
Axel ULLRICH
Keyword(s):  
Alternative Splicing ◽  
Catalytic Domain ◽  
Expression Patterns ◽  
Sr Proteins ◽  
Amino Acid Sequences ◽  
Sr Protein ◽  
High Sequence Identity ◽  
Mouse Tissues ◽  
Transformed Cell Lines

Phosphorylated serine- and arginine-rich (SR) proteins are components of the spliceosomal complex, and have been implicated in the control of alternative splicing. Kinases that regulate the phosphorylation and possibly the intranuclear distribution of SR proteins may therefore contribute to changes in choice of splice site. We have cloned three mouse cDNAs with high sequence identity to the family of LAMMER kinases (i.e. kinases carrying the conserved signature EHLAMMERILG in the catalytic domain). A comparison of their amino acid sequences revealed two related subfamilies with high evolutionary conservation. We have compared the expression patterns of these proteins in mouse tissues and transformed cell lines with that of a previously cloned family member (mCLK1/STY), and detected various transcripts for each gene. This underlines previous findings of alternative splicing of mclk1/STY. Our results suggest that the proportions of products for each gene are regulated independently. We further demonstrate that all variants encode autophosphorylating proteins that can phosphorylate several biochemically purified SR proteins in vitro, leading to hyperphosphorylation of at least one SR protein in vivo. The observed tissue distributions and substrate specificities suggest that these kinases may all be constituents of a network of regulatory mechanisms that enable SR proteins to control RNA splicing.

scholarly journals Regulation of Alternative Splicing by SRrp86 and Its Interacting Proteins

2003 ◽  
Vol 23 (21) ◽  
pp. 7437-7447 ◽  
Author(s):  
Jun Li ◽  
Ian C. Hawkins ◽  
Christopher D. Harvey ◽  
Jennifer L. Jennings ◽  
Andrew J. Link ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Sr Proteins ◽  
Splicing Factors ◽  
Rna Recognition Motif ◽  
Rna Recognition ◽  
Protein Activity ◽  
Splice Site Selection ◽  
Sr Protein ◽  
Library Screen ◽  
Specific Proteins

ABSTRACT SRrp86 is a unique member of the SR protein superfamily containing one RNA recognition motif and two serine-arginine (SR)-rich domains separated by an unusual glutamic acid-lysine (EK)-rich region. Previously, we showed that SRrp86 could regulate alternative splicing by both positively and negatively modulating the activity of other SR proteins and that the unique EK domain could inhibit both constitutive and alternative splicing. These functions were most consistent with the model in which SRrp86 functions by interacting with and thereby modulating the activity of target proteins. To identify the specific proteins that interact with SRrp86, we used a yeast two-hybrid library screen and immunoprecipitation coupled to mass spectrometry. We show that SRrp86 interacts with all of the core SR proteins, as well as a subset of other splicing regulatory proteins, including SAF-B, hnRNP G, YB-1, and p72. In contrast to previous results that showed activation of SRp20 by SRrp86, we now show that SAF-B, hnRNP G, and 9G8 all antagonize the activity of SRrp86. Overall, we conclude that not only does SRrp86 regulate SR protein activity but that it is, in turn, regulated by other splicing factors to control alternative splice site selection.

scholarly journals Biochemical and Genetic Conservation of Fission Yeast Dsk1 and Human SR Protein-Specific Kinase 1

2000 ◽  
Vol 20 (3) ◽  
pp. 816-824 ◽  
Author(s):  
Zhaohua Tang ◽  
Tiffany Kuo ◽  
Jenny Shen ◽  
Ren-Jang Lin
Keyword(s):  
Fission Yeast ◽  
Mammalian Cells ◽  
Specific Protein ◽  
Biochemical Properties ◽  
Growth Defect ◽  
Sr Protein ◽  
Kinase Gene ◽  
Control Circuits

ABSTRACT Arginine/serine-rich (RS) domain-containing proteins and their phosphorylation by specific protein kinases constitute control circuits to regulate pre-mRNA splicing and coordinate splicing with transcription in mammalian cells. We present here the finding that similar SR networks exist in Schizosaccharomyces pombe. We previously showed that Dsk1 protein, originally described as a mitotic regulator, displays high activity in phosphorylating S. pombe Prp2 protein (spU2AF59), a homologue of human U2AF65. We now demonstrate that Dsk1 also phosphorylates two recently identified fission yeast proteins with RS repeats, Srp1 and Srp2, in vitro. The phosphorylated proteins bear the same phosphoepitope found in mammalian SR proteins. Consistent with its substrate specificity, Dsk1 forms kinase-competent complexes with those proteins. Furthermore,dsk1 + gene determines the phenotype ofprp2 + overexpression, providing in vivo evidence that Prp2 is a target for Dsk1. The dsk1-null mutant strain became severely sick with the additional deletion of a related kinase gene. Significantly, human SR protein-specific kinase 1 (SRPK1) complements the growth defect of the double-deletion mutant. In conjunction with the resemblance of dsk1 + andSRPK1 in sequence homology, biochemical properties, and overexpression phenotypes, the complementation result indicates that SRPK1 is a functional homologue of Dsk1. Collectively, our studies illustrate the conserved SR networks in S. pombe consisting of RS domain-containing proteins and SR protein-specific kinases and thus establish the importance of the networks in eucaryotic organisms.

Human papillomavirus regulation of SR proteins

2010 ◽  
Vol 38 (4) ◽  
pp. 1116-1121 ◽  
Author(s):  
Melanie McFarlane ◽  
Sheila V. Graham
Keyword(s):  
Human Papillomavirus ◽  
Alternative Splicing ◽  
Sr Proteins ◽  
Hpv Infection ◽  
Splicing Factor ◽  
Sr Protein ◽  
Splicing Regulators ◽  
Constitutive Splicing ◽  
Rna Biogenesis ◽  
Specific Alternative

Splicing is a cellular process essential for mRNA biogenesis. There are two types of splicing: constitutive and alternative splicing. During constitutive splicing, non-coding intron sequences are removed and exonic coding sequences are spliced together to form mature mRNAs. Alternative splicing can maximize the coding capacity of the genome by specific alternative selection of exons from multi-exon metazoan pre-mRNAs. Splicing is a tightly regulated process, so when control is lost disease may occur. SR proteins (serine/arginine-rich proteins) are a family of highly conserved splicing regulators that are also involved in other steps in RNA biogenesis and expression. Many viruses have evolved to utilize the cellular splicing machinery to enhance their proteome from a limited number of genes. HPV (human papillomavirus) is an example of one such virus. The HPV transcription/replication factor E2 (early 2) specifically up-regulates expression of the SR proteins SF2/ASF (splicing factor 2/alternative splicing factor), SRp20 and SC35 in infected epithelial cells. These SR proteins are essential for viral RNA processing. SF2/ASF is a proto-oncogene that is also up-regulated in a number of cancers. For example, SF2/ASF, together with SRp20 and SC35 is selectively up-regulated in cervical tumours caused by persistent oncogenic HPV infection. However, the mode of SR protein up-regulation in tumours is different to the E2-directed transcriptional regulation in normal transient HPV infection. SR proteins could provide excellent targets for HPV antiviral therapy as well as anticancer therapy.

scholarly journals Central role of Akt in regulating Clk/Sty, serine/arginine‐rich (SR) protein phosphorylation and alternative splicing

2006 ◽  
Vol 20 (4) ◽  
Author(s):  
Denise R. Cooper ◽  
Karen D. Corbin ◽  
James E. Watson ◽  
Masatoshi Hagiwara ◽  
Niketa A. Patel ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Protein Phosphorylation ◽  
Sr Protein

scholarly journals Molecular Mechanism of SR Protein Kinase 1 Inhibition by the Herpes Virus Protein ICP27

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Richard B. Tunnicliffe ◽  
William K. Hu ◽  
Michele Y. Wu ◽  
Colin Levy ◽  
A. Paul Mould ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Alternative Splicing ◽  
Herpes Simplex ◽  
Protein Kinase ◽  
Molecular Mechanism ◽  
Sr Proteins ◽  
Sr Protein ◽  
High Affinity ◽  
Simplex Virus

ABSTRACT Serine-arginine (SR) protein kinase 1 (SRPK1) catalyzes the phosphorylation of SR proteins, which are a conserved family of splicing factors that contain a domain rich in arginine and serine repeats. SR proteins play important roles in constitutive pre-mRNA splicing and are also important regulators of alternative splicing. During herpes simplex virus infection, SRPK1 is inactivated and its cellular distribution is markedly altered by interaction with the viral protein ICP27, resulting in hypophosphorylation of SR proteins. Mutational analysis previously showed that the RGG box motif of ICP27 is required for interaction with SRPK1; however, the mechanism for the inhibition and the exact role of the RGG box was unknown. Here, we used solution nuclear magnetic resonance (NMR) spectroscopy and isothermal titration calorimetry (ITC) to demonstrate that the isolated peptide comprising the RGG box of ICP27 binds to SRPK1 with high affinity, competing with a native substrate, the SR repeat region of SR protein SRSF1. We determined the crystal structure of the complex between SRPK1 and an RGG box peptide, which revealed that the viral peptide binds to the substrate docking groove, mimicking the interactions of SR repeats. Site-directed mutagenesis within the RGG box further confirmed the importance of selected arginine residues for interaction, relocalization, and inhibition of SRPK1 in vivo. Together these data reveal the molecular mechanism of the competitive inhibition of cellular SRPK1 by viral ICP27, which modulates SRPK1 activity. IMPORTANCE Serine arginine (SR) proteins are a family of mRNA regulatory proteins that can modulate spliceosome association with different splice sites and therefore regulate alternative splicing. Phosphorylation within SR proteins is necessary for splice-site recognition, and this is catalyzed by SR protein kinase 1 (SRPK1). The herpes simplex virus (HSV-1) protein ICP27 has been shown previously to interact with and downregulate SRPK1 activity in vivo; however, the molecular mechanism for this interaction and inhibition was unknown. Here, we demonstrate that the isolated peptide fragment of ICP27 containing RGG box binds to SRPK1 with high affinity, and competes with a native cellular substrate. Elucidation of the SRPK1-RGG box crystal structure further showed that a short palindromic RGRRRGR sequence binds in the substrate docking groove of SRPK1, mimicking the binding of SR repeats of substrates. These data reveal how the viral protein ICP27 inactivates SRPK1, promoting hypophosphorylation of proteins regulating splicing.

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