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

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 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 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 Study of the Role of Splicing Factor SRRM2 in Cytarabine Treatment Resistance in Acute Myeloid Leukemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 8-9
Author(s):  
María Luz Morales ◽  
Roberto Garcia-Vicente ◽  
Noemí Álvarez Sánchez-Redondo ◽  
Alba Rodríguez García ◽  
Alejandra Ortiz-Ruiz ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Protein Phosphorylation ◽  
Myeloid Leukemia ◽  
Treatment Resistance ◽  
Sr Proteins ◽  
Sr Protein ◽  
Paired Samples ◽  
Public Data ◽  
Acute Myeloid

Introduction. Acute myeloid leukemia (AML) is a very complex and dynamic disease, characterized by clonal expansion of aberrantly differentiated myeloid lineage blasts. Although in recent years the molecular mechanisms involved in the development of the disease have been deeply studied, and as result many new targets have emerged, the treatment has not changed substantially. 7+3 chemotherapy regimens remains as the treatment of choice in most cases. Refractoriness and relapse after reaching complete remission are the main cause of death in the disease. Therefore, to improve current treatments it is crucial not only to know the molecular profile of patients at diagnosis, but also to know the mechanisms of pharmacological resistance that may be developed, in order to propose more appropriate and personalized treatments. Methods. The analysis of the proteomic profile associated to cytarabine treatment resistance of paired samples from 3 patients with AML was performed by LC-MSMS after IMAC enrichment. The OCI-AML3 cell line was used to generate a model of cytarabine resistance through sustained exposure to increasing doses of the drug, thus generating the OCI-AML3_R line (Figure 1A). Gene expression levels ofSRRM2were studied in the cell model (n=3), as well as in paired samples of AML patients (n=7) by qPCR; in addition to data deposited in public repositories from the TCGA-LAML and GTEx-BM projects. Finally, SR protein phosphorylation levels were studied in paired bone marrow smears by immunohistochemistry (n=7). Results. Proteomic analysis of paired samples from AML patients has identified an increased in the phosphorylation of SRRM2, among other SR proteins, at the time of cytarabine resistance. Analysis of public data has revealed several mutations and copy number variations in genes related to the spliceosome. However, these studies, as well asin vitroanalysis, have rejected that changes in SRRM2 phosphorylation are due to changes in gene or protein expression (Figure 1B and 1C). Otherwise a significant increase in SR protein phosphorylation has been detected after the development of cytarabine resistance by immunohistochemistry (Figure 1D). This increase in phosphorylation is prominent at the time of diagnosis in patients showing treatment refractoriness. Conclusions.The results obtained in this study show the involvement of the splicing pathway in AML and in cytarabine resistance. In addition, the immunohistochemistry analysis suggests a role of the phosphorylation levels of SR proteins as a possible predictive biomarker of response to cytarabine treatment. Disclosures No relevant conflicts of interest to declare.

SR protein kinases: the splice of life

1999 ◽  
Vol 77 (4) ◽  
pp. 293-298 ◽  
Author(s):  
David F Stojdl ◽  
John C Bell
Keyword(s):  
Alternative Splicing ◽  
Splice Site ◽  
Site Selection ◽  
Developmental Process ◽  
Messenger Rnas ◽  
Splice Site Selection ◽  
Sr Protein ◽  
Specific Alternative ◽  
Mature Mrnas

The eukaryotic genome codes for most of its proteins though discontinuous coding sequences called exons, which are separated by noncoding sequences known as introns. Following transcription of a gene, these exons must be spliced precisely, removing the intervening introns, to form meaningful mature messenger RNAs (mRNA) that are transported to the cytoplasm and translated by the ribosomal machinery. To add yet another level of complexity, a process known as alternative splicing exists, whereby a single pre-mRNA can give rise to two or more mature mRNAs depending on the combination of exons spliced together. Alternative splicing of pre-mRNAs is emerging as an important mechanism for gene regulation in many organisms. The classic example of splicing as a regulator of genetic information during a developmental process is sex determination in Drosophila. The now well-characterized cascade of sex-specific alternative splicing events demonstrates nicely how the control of splice site selection during pre-mRNA processing can have a profound effect on the development of an organism. The factors involved in pre-mRNA splicing and alternative splice site selection have been the subject of active study in recent years. Emerging from these studies is a picture of regulation based on protein-protein, protein-RNA, and RNA-RNA interactions. How the interaction of the various splicing constituents is controlled, however, is still poorly understood. One of the mechanisms of regulation that has received attention recently is that of posttranslational phosphorylation. In the following article, we cite the evidence for a role of phosphorylation in constitutive and alternative splicing and discuss some of the recent information on the biochemistry and biology of the enzymes involved.Key words: phosphorylation, splicing, spliceosome, Clk kinases, SR proteins.

scholarly journals PPM1G promotes the progression of hepatocellular carcinoma via phosphorylation regulation of alternative splicing protein SRSF3

2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Dawei Chen ◽  
Zhenguo Zhao ◽  
Lu Chen ◽  
Qinghua Li ◽  
Jixue Zou ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Alternative Splicing ◽  
Protein Function ◽  
Vital Role ◽  
Normal Tissues ◽  
Mechanistic Analysis ◽  
Highly Correlated ◽  
Splicing Patterns

AbstractEmerging evidence has demonstrated that alternative splicing has a vital role in regulating protein function, but how alternative splicing factors can be regulated remains unclear. We showed that the PPM1G, a protein phosphatase, regulated the phosphorylation of SRSF3 in hepatocellular carcinoma (HCC) and contributed to the proliferation, invasion, and metastasis of HCC. PPM1G was highly expressed in HCC tissues compared to adjacent normal tissues, and higher levels of PPM1G were observed in adverse staged HCCs. The higher levels of PPM1G were highly correlated with poor prognosis, which was further validated in the TCGA cohort. The knockdown of PPM1G inhibited the cell growth and invasion of HCC cell lines. Further studies showed that the knockdown of PPM1G inhibited tumor growth in vivo. The mechanistic analysis showed that the PPM1G interacted with proteins related to alternative splicing, including SRSF3. Overexpression of PPM1G promoted the dephosphorylation of SRSF3 and changed the alternative splicing patterns of genes related to the cell cycle, the transcriptional regulation in HCC cells. In addition, we also demonstrated that the promoter of PPM1G was activated by multiple transcription factors and co-activators, including MYC/MAX and EP300, MED1, and ELF1. Our study highlighted the essential role of PPM1G in HCC and shed new light on unveiling the regulation of alternative splicing in malignant transformation.

scholarly journals LncRNA CRNDE attenuates chemoresistance in gastric cancer via SRSF6-regulated alternative splicing of PICALM

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Feifei Zhang ◽  
Hui Wang ◽  
Jiang Yu ◽  
Xueqing Yao ◽  
Shibin Yang ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Alternative Splicing ◽  
Noncoding Rna ◽  
De Novo ◽  
Acquired Resistance ◽  
Genetic Alterations ◽  
Clinical Samples ◽  
Autophagy Flux ◽  
Resistance To Chemotherapy

AbstractDe novo and acquired resistance, which are mainly mediated by genetic alterations, are barriers to effective routine chemotherapy. However, the mechanisms underlying gastric cancer (GC) resistance to chemotherapy are still unclear. We showed that the long noncoding RNA CRNDE was related to the chemosensitivity of GC in clinical samples and a PDX model. CRNDE was decreased and inhibited autophagy flux in chemoresistant GC cells. CRNDE directly bound to splicing protein SRSF6 to reduce its protein stability and thus regulate alternative splicing (AS) events. We determined that SRSF6 regulated the PICALM exon 14 skip splice variant and triggered a significant S-to-L isoform switch, which contributed to the expression of the long isoform of PICALM (encoding PICALML). Collectively, our findings reveal the key role of CRNDE in autophagy regulation, highlighting the significance of CRNDE as a potential prognostic marker and therapeutic target against chemoresistance in GC.

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