1
|
Habib EB, Mathavarajah S, Dellaire G. Tinker, Tailor, Tumour Suppressor: The Many Functions of PRP4K. Front Genet 2022; 13:839963. [PMID: 35281802 PMCID: PMC8912934 DOI: 10.3389/fgene.2022.839963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 01/28/2022] [Indexed: 11/13/2022] Open
Abstract
Pre-mRNA processing factor 4 kinase (PRP4K, also known as PRPF4B) is an essential kinase first identified in the fission yeast Schizosaccharomyces pombe that is evolutionarily conserved from amoebae to animals. During spliceosomal assembly, PRP4K interacts with and phosphorylates PRPF6 and PRPF31 to facilitate the formation of the spliceosome B complex. However, over the past decade additional evidence has emerged that PRP4K has many diverse cellular roles beyond splicing that contribute to tumour suppression and chemotherapeutic responses in mammals. For example, PRP4K appears to play roles in regulating transcription and the spindle assembly checkpoint (SAC), a key pathway in maintaining chromosomes stability and the response of cancer cells to taxane-based chemotherapy. In addition, PRP4K has been revealed to be a haploinsufficient tumour suppressor that promotes aggressive cancer phenotypes when partially depleted. PRP4K is regulated by both the HER2 and estrogen receptor, and its partial loss increases resistance to the taxanes in multiple malignancies including cervical, breast and ovarian cancer. Moreover, ovarian and triple negative breast cancer patients harboring tumours with low PRP4K expression exhibit worse overall survival. The depletion of PRP4K also enhances both Yap and epidermal growth factor receptor (EGFR) signaling, the latter promoting anoikis resistance in breast and ovarian cancer. Finally, PRP4K is negatively regulated during epithelial-to-mesenchymal transition (EMT), a process that promotes increased cell motility, drug resistance and cancer metastasis. Thus, as we discuss in this review, PRP4K likely plays evolutionarily conserved roles not only in splicing but in a number of cellular pathways that together contribute to tumour suppression.
Collapse
Affiliation(s)
- Elias B. Habib
- Dalhousie University, Department of Pathology, Halifax, NS, Canada
| | | | - Graham Dellaire
- Dalhousie University, Department of Pathology, Halifax, NS, Canada
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada
- Beatrice Hunter Cancer Research Institute, Halifax, NS, Canada
- *Correspondence: Graham Dellaire,
| |
Collapse
|
2
|
PRP4 Promotes Skin Cancer by Inhibiting Production of Melanin, Blocking Influx of Extracellular Calcium, and Remodeling Cell Actin Cytoskeleton. Int J Mol Sci 2021; 22:ijms22136992. [PMID: 34209674 PMCID: PMC8268783 DOI: 10.3390/ijms22136992] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 11/16/2022] Open
Abstract
Pre-mRNA processing factor 4B (PRP4) has previously been shown to induce epithelial-mesenchymal transition (EMT) and drug resistance in cancer cell lines. As melanin plays an important photoprotective role in the risk of sun-induced skin cancers, we have investigated whether PRP4 can induce drug resistance and regulate melanin biosynthesis in a murine melanoma (B16F10) cell line. Cells were incubated with a crucial melanogenesis stimulator, alpha-melanocyte-stimulating hormone, followed by transfection with PRP4. This resulted in the inhibition of the production of melanin via the downregulation of adenylyl cyclase-cyclic adenosine 3′,5′-monophosphate (AC)–(cAMP)–tyrosinase synthesis signaling pathway. Inhibition of melanin production by PRP4 leads to the promotion of carcinogenesis and induced drug resistance in B16F10 cells. Additionally, PRP4 overexpression upregulated the expression of β-arrestin 1 and desensitized the extracellular calcium-sensing receptor (CaSR), which in turn, inhibited the influx of extracellular Ca2+ ions. The decreased influx of Ca2+ was confirmed by a decreased expression level of calmodulin. We have demonstrated that transient receptor potential cation channel subfamily C member 1 was involved in the influx of CaSR-induced Ca2+ via a decreasing level of its expression. Furthermore, PRP4 overexpression downregulated the expression of AC, decreased the synthesis of cAMP, and modulated the actin cytoskeleton by inhibiting the expression of Ras homolog family member A (RhoA). Our investigation suggests that PRP4 inhibits the production of melanin in B16F10 cells, blocks the influx of Ca2+ through desensitization of CaSR, and modulates the actin cytoskeleton through downregulating the AC–cAMP pathway; taken together, these observations collectively lead to the promotion of skin carcinogenesis.
Collapse
|
3
|
Pastor F, Shkreta L, Chabot B, Durantel D, Salvetti A. Interplay Between CMGC Kinases Targeting SR Proteins and Viral Replication: Splicing and Beyond. Front Microbiol 2021; 12:658721. [PMID: 33854493 PMCID: PMC8040976 DOI: 10.3389/fmicb.2021.658721] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/04/2021] [Indexed: 12/27/2022] Open
Abstract
Protein phosphorylation constitutes a major post-translational modification that critically regulates the half-life, intra-cellular distribution, and activity of proteins. Among the large number of kinases that compose the human kinome tree, those targeting RNA-binding proteins, in particular serine/arginine-rich (SR) proteins, play a major role in the regulation of gene expression by controlling constitutive and alternative splicing. In humans, these kinases belong to the CMGC [Cyclin-dependent kinases (CDKs), Mitogen-activated protein kinases (MAPKs), Glycogen synthase kinases (GSKs), and Cdc2-like kinases (CLKs)] group and several studies indicate that they also control viral replication via direct or indirect mechanisms. The aim of this review is to describe known and emerging activities of CMGC kinases that share the common property to phosphorylate SR proteins, as well as their interplay with different families of viruses, in order to advance toward a comprehensive knowledge of their pro- or anti-viral phenotype and better assess possible translational opportunities.
Collapse
Affiliation(s)
- Florentin Pastor
- International Center for Infectiology Research (CIRI), INSERM U1111, CNRS UMR5308, Université de Lyon (UCBL1), Lyon, France
| | - Lulzim Shkreta
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Benoit Chabot
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - David Durantel
- International Center for Infectiology Research (CIRI), INSERM U1111, CNRS UMR5308, Université de Lyon (UCBL1), Lyon, France
| | - Anna Salvetti
- International Center for Infectiology Research (CIRI), INSERM U1111, CNRS UMR5308, Université de Lyon (UCBL1), Lyon, France
| |
Collapse
|
4
|
Märker R, Blank-Landeshammer B, Beier-Rosberger A, Sickmann A, Kück U. Phosphoproteomic analysis of STRIPAK mutants identifies a conserved serine phosphorylation site in PAK kinase CLA4 to be important in fungal sexual development and polarized growth. Mol Microbiol 2020; 113:1053-1069. [PMID: 32022307 DOI: 10.1111/mmi.14475] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 01/16/2020] [Accepted: 01/20/2020] [Indexed: 02/06/2023]
Abstract
The highly conserved striatin-interacting phosphatases and kinases (STRIPAK) complex regulates phosphorylation/dephosphorylation of developmental proteins in eukaryotic microorganisms, animals and humans. To first identify potential targets of STRIPAK, we performed extensive isobaric tags for relative and absolute quantification-based proteomic and phosphoproteomic analyses in the filamentous fungus Sordaria macrospora. In total, we identified 4,193 proteins and 2,489 phosphoproteins, which are represented by 10,635 phosphopeptides. By comparing phosphorylation data from wild type and mutants, we identified 228 phosphoproteins to be regulated in all three STRIPAK mutants, thus representing potential targets of STRIPAK. To provide an exemplarily functional analysis of a STRIPAK-dependent phosphorylated protein, we selected CLA4, a member of the conserved p21-activated kinase family. Functional characterization of the ∆cla4 deletion strain showed that CLA4 controls sexual development and polarized growth. To determine the functional relevance of CLA4 phosphorylation and the impact of specific phosphorylation sites on development, we next generated phosphomimetic and -deficient variants of CLA4. This analysis identified (de)phosphorylation of a highly conserved serine (S685) residue in the catalytic domain of CLA4 as being important for fungal cellular development. Collectively, these analyses significantly contribute to the understanding of the mechanistic function of STRIPAK as a phosphatase and kinase signaling complex.
Collapse
Affiliation(s)
- Ramona Märker
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität, Bochum, Germany
| | | | - Anna Beier-Rosberger
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität, Bochum, Germany
| | - Albert Sickmann
- Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Dortmund, Germany
| | - Ulrich Kück
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität, Bochum, Germany
| |
Collapse
|
5
|
PRPF overexpression induces drug resistance through actin cytoskeleton rearrangement and epithelial-mesenchymal transition. Oncotarget 2017; 8:56659-56671. [PMID: 28915620 PMCID: PMC5593591 DOI: 10.18632/oncotarget.17855] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 04/12/2017] [Indexed: 11/25/2022] Open
Abstract
Pre-mRNA processing factor (PRPF) 4B kinase belongs to the CDK-like kinase family, and is involved in pre-mRNA splicing, and in signal transduction. In this study, we observed that PRPF overexpression decreased the intracellular levels of reactive oxygen species, and inhibited resveratrol-induced apoptosis by activating the cell survival signaling proteins NFκB, ERK, and c-MYC in HCT116 human colon cancer cells. PRPF overexpression altered cellular morphology, and rearranged the actin cytoskeleton, by regulating the activity of Rho family proteins. Moreover, it decreased the activity of RhoA, but increased the expression of Rac1. In addition, PRPF triggered the epithelial-mesenchymal transition (EMT), and decreased the invasiveness of HCT116, PC3 human prostate, and B16-F10 melanoma cells. The loss of E-cadherin, a hallmark of EMT, was observed in HCT116 cells overexpressing PRPF. Taken together, these results indicate that PRPF blocks the apoptotic effects of resveratrol by activating cell survival signaling pathways, rearranging the actin cytoskeleton, and inducing EMT. The elucidation of the mechanisms that underlie anticancer drug resistance and the anti-apoptosis effect of PRPF may provide a therapeutic basis for inhibiting tumor growth and preventing metastasis in various cancers.
Collapse
|
6
|
Vijaykrishna N, Melangath G, Kumar R, Khandelia P, Bawa P, Varadarajan R, Vijayraghavan U. The Fission Yeast Pre-mRNA-processing Factor 18 (prp18+) Has Intron-specific Splicing Functions with Links to G1-S Cell Cycle Progression. J Biol Chem 2016; 291:27387-27402. [PMID: 27875300 DOI: 10.1074/jbc.m116.751289] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 11/11/2016] [Indexed: 12/24/2022] Open
Abstract
The fission yeast genome, which contains numerous short introns, is an apt model for studies on fungal splicing mechanisms and splicing by intron definition. Here we perform a domain analysis of the evolutionarily conserved Schizosaccharomyces pombe pre-mRNA-processing factor, SpPrp18. Our mutational and biophysical analyses of the C-terminal α-helical bundle reveal critical roles for the conserved region as well as helix five. We generate a novel conditional missense mutant, spprp18-5 To assess the role of SpPrp18, we performed global splicing analyses on cells depleted of prp18+ and the conditional spprp18-5 mutant, which show widespread but intron-specific defects. In the absence of functional SpPrp18, primer extension analyses on a tfIId+ intron 1-containing minitranscript show accumulated pre-mRNA, whereas the lariat intron-exon 2 splicing intermediate was undetectable. These phenotypes also occurred in cells lacking both SpPrp18 and SpDbr1 (lariat debranching enzyme), a genetic background suitable for detection of lariat RNAs. These data indicate a major precatalytic splicing arrest that is corroborated by the genetic interaction between spprp18-5 and spprp2-1, a mutant in the early acting U2AF59 protein. Interestingly, SpPrp18 depletion caused cell cycle arrest before S phase. The compromised splicing of transcripts coding for G1-S regulators, such as Res2, a transcription factor, and Skp1, a regulated proteolysis factor, are shown. The cumulative effects of SpPrp18-dependent intron splicing partly explain the G1 arrest upon the loss of SpPrp18. Our study using conditional depletion of spprp18+ and the spprp18-5 mutant uncovers an intron-specific splicing function and early spliceosomal interactions and suggests links with cell cycle progression.
Collapse
Affiliation(s)
| | | | - Rakesh Kumar
- From the Department of Microbiology and Cell Biology and
| | | | | | - Raghavan Varadarajan
- the Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | | |
Collapse
|
7
|
Sesma A. RNA metabolism and regulation of virulence programs in fungi. Semin Cell Dev Biol 2016; 57:120-127. [DOI: 10.1016/j.semcdb.2016.03.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/21/2016] [Accepted: 03/23/2016] [Indexed: 01/16/2023]
|
8
|
Effenberger KA, Urabe VK, Jurica MS. Modulating splicing with small molecular inhibitors of the spliceosome. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 8. [PMID: 27440103 DOI: 10.1002/wrna.1381] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 06/06/2016] [Accepted: 06/28/2016] [Indexed: 12/23/2022]
Abstract
Small molecule inhibitors that target components of the spliceosome have great potential as tools to probe splicing mechanism and dissect splicing regulatory networks in cells. These compounds also hold promise as drug leads for diseases in which splicing regulation plays a critical role, including many cancers. Because the spliceosome is a complicated and dynamic macromolecular machine comprised of many RNA and protein components, a variety of compounds that interfere with different aspects of spliceosome assembly is needed to probe its function. By screening chemical libraries with high-throughput splicing assays, several labs have added to the collection of splicing inhibitors, although the mechanistic insight into splicing yielded from the initial compound hits is somewhat limited so far. In contrast, SF3B1 inhibitors stand out as a great example of what can be accomplished with small molecule tools. This group of compounds were first discovered as natural products that are cytotoxic to cancer cells, and then later shown to target the core spliceosome protein SF3B1. The inhibitors have since been used to uncover details of SF3B1 mechanism in the spliceosome and its impact on gene expression in cells. Continuing structure activity relationship analysis of the compounds is also making progress in identifying chemical features key to their function, which is critical in understanding the mechanism of SF3B1 inhibition. The knowledge is also important for the design of analogs with new and useful features for both splicing researchers and clinicians hoping to exploit splicing as pressure point to target in cancer therapy. WIREs RNA 2017, 8:e1381. doi: 10.1002/wrna.1381 For further resources related to this article, please visit the WIREs website.
Collapse
Affiliation(s)
- Kerstin A Effenberger
- Department of Molecular Cell and Developmental Biology, University of California, Santa Cruz, CA, USA.,Center for Molecular Biology of RNA, University of California, Santa Cruz, CA, USA
| | - Veronica K Urabe
- Department of Molecular Cell and Developmental Biology, University of California, Santa Cruz, CA, USA.,Center for Molecular Biology of RNA, University of California, Santa Cruz, CA, USA
| | - Melissa S Jurica
- Department of Molecular Cell and Developmental Biology, University of California, Santa Cruz, CA, USA.,Center for Molecular Biology of RNA, University of California, Santa Cruz, CA, USA
| |
Collapse
|
9
|
Gao X, Jin Q, Jiang C, Li Y, Li C, Liu H, Kang Z, Xu JR. FgPrp4 Kinase Is Important for Spliceosome B-Complex Activation and Splicing Efficiency in Fusarium graminearum. PLoS Genet 2016; 12:e1005973. [PMID: 27058959 PMCID: PMC4825928 DOI: 10.1371/journal.pgen.1005973] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 03/11/2016] [Indexed: 12/23/2022] Open
Abstract
PRP4 encodes the only kinase among the spliceosome components. Although it is an essential gene in the fission yeast and other eukaryotic organisms, the Fgprp4 mutant was viable in the wheat scab fungus Fusarium graminearum. Deletion of FgPRP4 did not block intron splicing but affected intron splicing efficiency in over 60% of the F. graminearum genes. The Fgprp4 mutant had severe growth defects and produced spontaneous suppressors that were recovered in growth rate. Suppressor mutations were identified in the PRP6, PRP31, BRR2, and PRP8 orthologs in nine suppressor strains by sequencing analysis with candidate tri-snRNP component genes. The Q86K mutation in FgMSL1 was identified by whole genome sequencing in suppressor mutant S3. Whereas two of the suppressor mutations in FgBrr2 and FgPrp8 were similar to those characterized in their orthologs in yeasts, suppressor mutations in Prp6 and Prp31 orthologs or FgMSL1 have not been reported. Interestingly, four and two suppressor mutations identified in FgPrp6 and FgPrp31, respectively, all are near the conserved Prp4-phosphorylation sites, suggesting that these mutations may have similar effects with phosphorylation by Prp4 kinase. In FgPrp31, the non-sense mutation at R464 resulted in the truncation of the C-terminal 130 aa region that contains all the conserved Prp4-phosphorylation sites. Deletion analysis showed that the N-terminal 310-aa rich in SR residues plays a critical role in the localization and functions of FgPrp4. We also conducted phosphoproteomics analysis with FgPrp4 and identified S289 as the phosphorylation site that is essential for its functions. These results indicated that FgPrp4 is critical for splicing efficiency but not essential for intron splicing, and FgPrp4 may regulate pre-mRNA splicing by phosphorylation of other components of the tri-snRNP although itself may be activated by phosphorylation at S289.
Collapse
Affiliation(s)
- Xuli Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Qiaojun Jin
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Cong Jiang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Dept. of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Yang Li
- Dept. of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Chaohui Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Jin-Rong Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Dept. of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
| |
Collapse
|
10
|
Eckert D, Andrée N, Razanau A, Zock-Emmenthal S, Lützelberger M, Plath S, Schmidt H, Guerra-Moreno A, Cozzuto L, Ayté J, Käufer NF. Prp4 Kinase Grants the License to Splice: Control of Weak Splice Sites during Spliceosome Activation. PLoS Genet 2016; 12:e1005768. [PMID: 26730850 PMCID: PMC4701394 DOI: 10.1371/journal.pgen.1005768] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 12/03/2015] [Indexed: 12/02/2022] Open
Abstract
The genome of the fission yeast Schizosaccharomyces pombe encodes 17 kinases that are essential for cell growth. These include the cell-cycle regulator Cdc2, as well as several kinases that coordinate cell growth, polarity, and morphogenesis during the cell cycle. In this study, we further characterized another of these essential kinases, Prp4, and showed that the splicing of many introns is dependent on Prp4 kinase activity. For detailed characterization, we chose the genes res1 and ppk8, each of which contains one intron of typical size and position. Splicing of the res1 intron was dependent on Prp4 kinase activity, whereas splicing of the ppk8 intron was not. Extensive mutational analyses of the 5’ splice site of both genes revealed that proper transient interaction with the 5’ end of snRNA U1 governs the dependence of splicing on Prp4 kinase activity. Proper transient interaction between the branch sequence and snRNA U2 was also important. Therefore, the Prp4 kinase is required for recognition and efficient splicing of introns displaying weak exon1/5’ splice sites and weak branch sequences. Prp4 is an essential protein kinase that is involved in the splicing of some introns. Using a conditional mutant of Prp4, we showed that a subset of genes, including several cell cycle–regulatory genes, are dependent on Prp4 for splicing. Furthermore, we could convert genes between Prp4-dependent and -independent states by introducing single-nucleotide mutations in the exon1/5’ splice sites and branch sequence of introns. This work shows that Prp4 activity is required for splicing surveillance in a subset of mRNAs.
Collapse
Affiliation(s)
- Daniela Eckert
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Nicole Andrée
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Aleh Razanau
- Department of Physiology and Pathophysiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
| | | | - Martin Lützelberger
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Susann Plath
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Henning Schmidt
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Angel Guerra-Moreno
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
| | - Luca Cozzuto
- CRG Bioinformatics Core, Centre de Regulació Genòmica (CRG), and Universitat Pompeu Fabra, Barcelona, Spain
| | - José Ayté
- Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain
- * E-mail: (JA); (NFK)
| | - Norbert F. Käufer
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
- * E-mail: (JA); (NFK)
| |
Collapse
|
11
|
Curcumin induces radiosensitivity of in vitro and in vivo cancer models by modulating pre-mRNA processing factor 4 (Prp4). Chem Biol Interact 2013; 206:394-402. [PMID: 24144778 DOI: 10.1016/j.cbi.2013.10.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 09/20/2013] [Accepted: 10/08/2013] [Indexed: 12/21/2022]
Abstract
Radiation therapy plays a central role in adjuvant strategies for the treatment of both pre- and post-operative human cancers. However, radiation therapy has low efficacy against cancer cells displaying radio-resistant phenotypes. Ionizing radiation has been shown to enhance ROS generation, which mediates apoptotic cell death. Further, concomitant use of sensitizers with radiation improves the efficiency of radiotherapy against a variety of human cancers. Here, the radio-sensitizing effect of curcumin (a derivative of turmeric) was investigated against growth of HCT-15 cells and tumor induction in C57BL/6J mice. Ionizing radiation induced apoptosis through ROS generation and down-regulation of Prp4K, which was further potentiated by curcumin treatment. Flow cytometry revealed a dose-dependent response for radiation-induced cell death, which was remarkably reversed by transfection of cells with Prp4K clone. Over-expression of Prp4K resulted in a significant decrease in ROS production possibly through activation of an anti-oxidant enzyme system. To elucidate an integrated mechanism, Prp4K knockdown by siRNA ultimately restored radiation-induced ROS generation. Furthermore, B16F10 xenografts in C57BL/6J mice were established in order to investigate the radio-sensitizing effect of curcumin in vivo. Curcumin significantly enhanced the efficacy of radiation therapy and reduced tumor growth as compared to control or radiation alone. Collectively, these results suggest a novel mechanism for curcumin-mediated radio-sensitization of cancer based on ROS generation and down-regulation of Prp4K.
Collapse
|
12
|
Gao Q, Mechin I, Kothari N, Guo Z, Deng G, Haas K, McManus J, Hoffmann D, Wang A, Wiederschain D, Rocnik J, Czechtizky W, Chen X, McLean L, Arlt H, Harper D, Liu F, Majid T, Patel V, Lengauer C, Garcia-Echeverria C, Zhang B, Cheng H, Dorsch M, Huang SMA. Evaluation of cancer dependence and druggability of PRP4 kinase using cellular, biochemical, and structural approaches. J Biol Chem 2013; 288:30125-30138. [PMID: 24003220 DOI: 10.1074/jbc.m113.473348] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
PRP4 kinase is known for its roles in regulating pre-mRNA splicing and beyond. Therefore, a wider spectrum of PRP4 kinase substrates could be expected. The role of PRP4 kinase in cancer is also yet to be fully elucidated. Attaining specific and potent PRP4 inhibitors would greatly facilitate the study of PRP4 biological function and its validation as a credible cancer target. In this report, we verified the requirement of enzymatic activity of PRP4 in regulating cancer cell growth and identified an array of potential novel substrates through orthogonal proteomics approaches. The ensuing effort in structural biology unveiled for the first time unique features of PRP4 kinase domain and its potential mode of interaction with a low molecular weight inhibitor. These results provide new and important information for further exploration of PRP4 kinase function in cancer.
Collapse
Affiliation(s)
- Qiang Gao
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Ingrid Mechin
- Tucson Research Center, Sanofi, Tucson, Arizona 85755
| | - Nayantara Kothari
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Zhuyan Guo
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Gejing Deng
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Kimberly Haas
- Lead Generation and Candidate Realization, Sanofi, Bridgewater, New Jersey 08807, and
| | - Jessica McManus
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Dietmar Hoffmann
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Anlai Wang
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Dmitri Wiederschain
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Jennifer Rocnik
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Werngard Czechtizky
- Lead Generation and Candidate Realization, Sanofi, Industriepark Höchst, 65926 Frankfurt, Germany
| | - Xin Chen
- Lead Generation and Candidate Realization, Sanofi, Bridgewater, New Jersey 08807, and
| | - Larry McLean
- Lead Generation and Candidate Realization, Sanofi, Bridgewater, New Jersey 08807, and
| | - Heike Arlt
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - David Harper
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Feng Liu
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Tahir Majid
- Lead Generation and Candidate Realization, Sanofi, Waltham, Massachusetts 02451
| | - Vinod Patel
- Lead Generation and Candidate Realization, Sanofi, Waltham, Massachusetts 02451
| | - Christoph Lengauer
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Carlos Garcia-Echeverria
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Bailin Zhang
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Hong Cheng
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Marion Dorsch
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France
| | - Shih-Min A Huang
- From Discovery and Early Development, Sanofi Oncology, Cambridge, Massachusetts 02139 and 94400 Vitry-sur-Seine Cedex, France,.
| |
Collapse
|
13
|
Shehzad A, Lee J, Huh TL, Lee YS. Curcumin induces apoptosis in human colorectal carcinoma (HCT-15) cells by regulating expression of Prp4 and p53. Mol Cells 2013; 35:526-32. [PMID: 23686430 PMCID: PMC3887881 DOI: 10.1007/s10059-013-0038-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 03/13/2013] [Accepted: 03/28/2013] [Indexed: 12/30/2022] Open
Abstract
Curcumin (diferuloylmethane), the yellow pigment of turmeric, is one of the most commonly used and extensively studied phytochemicals due to its pleiotropic effects in several human cancers. In the current study, the therapeutic efficacy of curcumin was investigated in human colorectal carcinoma HCT-15 cells. Curcumin inhibited HCT-15 cells proliferation and induced apoptosis in a dose- and time-dependent manner. Hoechst 33342 and DCFHDA staining revealed morphological and biochemical features of apoptosis as well as ROS generation in HCT-15 cells treated with 30 and 50 μM curcumin. Over-expression of pre-mRNA processing factor 4B (Prp4B) and p53 mutations have been reported as hallmarks of cancer cells. Western blot analysis revealed that curcumin treatment activated caspase-3 and decreased expression of p53 and Prp4B in a time-dependent manner. Transfection of HCT-15 cells with Prp4B clone perturbed the growth inhibition induced by 30 μM curcumin. Fractionation of cells revealed increased accumulation of Prp4B in the nucleus, following its translocation from the cytoplasm. To further evaluate the underlying mechanism and survival effect of Prp4B, we generated siRNA-Prp4B HCT15 clones. Knockdown of Prp4B with siRNA diminished the protective effects of Prp4B against curcumin-induced apoptosis. These results suggest a possible underlying molecular mechanism in which Prp4B over-expression and activity are closely associated with the survival and regulation of apoptotic events in human colon cancer HCT-15 cells.
Collapse
Affiliation(s)
- Adeeb Shehzad
- School of Life Sciences, College of Natural Sciences, Kyungpook National University
| | | | - Tae-Lin Huh
- School of Life Sciences, College of Natural Sciences, Kyungpook National University
| | - Young Sup Lee
- School of Life Sciences, College of Natural Sciences, Kyungpook National University
| |
Collapse
|
14
|
Fleißner A. Turning the switch: using chemical genetics to elucidate protein kinase functions in filamentous fungi. FUNGAL BIOL REV 2013. [DOI: 10.1016/j.fbr.2013.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
15
|
Abstract
The filamentous fungi are an ecologically important group of organisms which also have important industrial applications but devastating effects as pathogens and agents of food spoilage. Protein kinases have been implicated in the regulation of virtually all biological processes but how they regulate filamentous fungal specific processes is not understood. The filamentous fungus Aspergillus nidulans has long been utilized as a powerful molecular genetic system and recent technical advances have made systematic approaches to study large gene sets possible. To enhance A. nidulans functional genomics we have created gene deletion constructs for 9851 genes representing 93.3% of the encoding genome. To illustrate the utility of these constructs, and advance the understanding of fungal kinases, we have systematically generated deletion strains for 128 A. nidulans kinases including expanded groups of 15 histidine kinases, 7 SRPK (serine-arginine protein kinases) kinases and an interesting group of 11 filamentous fungal specific kinases. We defined the terminal phenotype of 23 of the 25 essential kinases by heterokaryon rescue and identified phenotypes for 43 of the 103 non-essential kinases. Uncovered phenotypes ranged from almost no growth for a small number of essential kinases implicated in processes such as ribosomal biosynthesis, to conditional defects in response to cellular stresses. The data provide experimental evidence that previously uncharacterized kinases function in the septation initiation network, the cell wall integrity and the morphogenesis Orb6 kinase signaling pathways, as well as in pathways regulating vesicular trafficking, sexual development and secondary metabolism. Finally, we identify ChkC as a third effector kinase functioning in the cellular response to genotoxic stress. The identification of many previously unknown functions for kinases through the functional analysis of the A. nidulans kinome illustrates the utility of the A. nidulans gene deletion constructs.
Collapse
|
16
|
Discovery of a splicing regulator required for cell cycle progression. PLoS Genet 2013; 9:e1003305. [PMID: 23437009 PMCID: PMC3578776 DOI: 10.1371/journal.pgen.1003305] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 12/19/2012] [Indexed: 01/30/2023] Open
Abstract
In the G1 phase of the cell division cycle, eukaryotic cells prepare many of the resources necessary for a new round of growth including renewal of the transcriptional and protein synthetic capacities and building the machinery for chromosome replication. The function of G1 has an early evolutionary origin and is preserved in single and multicellular organisms, although the regulatory mechanisms conducting G1 specific functions are only understood in a few model eukaryotes. Here we describe a new G1 mutant from an ancient family of apicomplexan protozoans. Toxoplasma gondii temperature-sensitive mutant 12-109C6 conditionally arrests in the G1 phase due to a single point mutation in a novel protein containing a single RNA-recognition-motif (TgRRM1). The resulting tyrosine to asparagine amino acid change in TgRRM1 causes severe temperature instability that generates an effective null phenotype for this protein when the mutant is shifted to the restrictive temperature. Orthologs of TgRRM1 are widely conserved in diverse eukaryote lineages, and the human counterpart (RBM42) can functionally replace the missing Toxoplasma factor. Transcriptome studies demonstrate that gene expression is downregulated in the mutant at the restrictive temperature due to a severe defect in splicing that affects both cell cycle and constitutively expressed mRNAs. The interaction of TgRRM1 with factors of the tri-SNP complex (U4/U6 & U5 snRNPs) indicate this factor may be required to assemble an active spliceosome. Thus, the TgRRM1 family of proteins is an unrecognized and evolutionarily conserved class of splicing regulators. This study demonstrates investigations into diverse unicellular eukaryotes, like the Apicomplexa, have the potential to yield new insights into important mechanisms conserved across modern eukaryotic kingdoms. The study of eukaryotic cell division has overwhelmingly focused on cells from two branches of evolution, fungal and metazoan, with more distant eukaryotes rarely studied. One exception is apicomplexan pathogens where in the last two decades development of genetic models has been rapid. While not a perfect solution to fill the missing evolutionary diversity, Apicomplexans represent one of the oldest eukaryotic lineages possibly pre-dating the divergence of plant and animal kingdoms. A key to uncovering novel and conserved cell cycle mechanisms in these protists was the development of forward genetic approaches that permit unbiased discovery of essential growth factors. The apicomplexan, Toxoplasma has provided the best resource so far with ∼60,000 chemical mutants yielding a collection of 165 temperature-sensitive isolates that arrest in all phases of the parasite cell cycle. Efforts to identify the defective genes in this model are providing insights into the regulatory factors possibly active in the original eukaryote cell cycle, like the mRNA splicing factor discovered in this study.
Collapse
|
17
|
Wang C, Zhang S, Hou R, Zhao Z, Zheng Q, Xu Q, Zheng D, Wang G, Liu H, Gao X, Ma JW, Kistler HC, Kang Z, Xu JR. Functional analysis of the kinome of the wheat scab fungus Fusarium graminearum. PLoS Pathog 2011; 7:e1002460. [PMID: 22216007 PMCID: PMC3245316 DOI: 10.1371/journal.ppat.1002460] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Accepted: 11/11/2011] [Indexed: 02/04/2023] Open
Abstract
As in other eukaryotes, protein kinases play major regulatory roles in filamentous fungi. Although the genomes of many plant pathogenic fungi have been sequenced, systematic characterization of their kinomes has not been reported. The wheat scab fungus Fusarium graminearum has 116 protein kinases (PK) genes. Although twenty of them appeared to be essential, we generated deletion mutants for the other 96 PK genes, including 12 orthologs of essential genes in yeast. All of the PK mutants were assayed for changes in 17 phenotypes, including growth, conidiation, pathogenesis, stress responses, and sexual reproduction. Overall, deletion of 64 PK genes resulted in at least one of the phenotypes examined, including three mutants blocked in conidiation and five mutants with increased tolerance to hyperosmotic stress. In total, 42 PK mutants were significantly reduced in virulence or non-pathogenic, including mutants deleted of key components of the cAMP signaling and three MAPK pathways. A number of these PK genes, including Fg03146 and Fg04770 that are unique to filamentous fungi, are dispensable for hyphal growth and likely encode novel fungal virulence factors. Ascospores play a critical role in the initiation of wheat scab. Twenty-six PK mutants were blocked in perithecia formation or aborted in ascosporogenesis. Additional 19 mutants were defective in ascospore release or morphology. Interestingly, F. graminearum contains two aurora kinase genes with distinct functions, which has not been reported in fungi. In addition, we used the interlog approach to predict the PK-PK and PK-protein interaction networks of F. graminearum. Several predicted interactions were verified with yeast two-hybrid or co-immunoprecipitation assays. To our knowledge, this is the first functional characterization of the kinome in plant pathogenic fungi. Protein kinase genes important for various aspects of growth, developmental, and infection processes in F. graminearum were identified in this study. Fusarium head blight caused by Fusarium graminearum is one of the most important diseases on wheat and barley. Although protein kinases are known to play major regulatory roles in fungi, systematic characterization of fungal kinomes has not been reported in plant pathogens. In this study we generated deletion mutants for 96 protein kinase genes. All of the resulting knockout mutants were assayed for changes in 17 phenotypes, including growth, reproduction, stress responses, and plant infection. Overall, deletion of 64 kinase genes resulted in at least one of the phenotypes examined. In total, 42 kinase mutants were significantly reduced in virulence or non-pathogenic. A number of these protein kinase genes, including two that are unique to filamentous fungi, are dispensable for hyphal growth and likely encode novel fungal virulence factors. Ascospores are the primary inoculum for wheat scab. We identified 26 mutants blocked in ascospore. We also used the in silico approach to predict the kinase-kinase interactions and verified some of them by yeast two-hybrid or co-IP assays. Overall, in this study we functionally characterize the kinome of F. graminearum. Protein kinase genes that are important for various aspects of growth, developmental, and plant infection processes were identified.
Collapse
Affiliation(s)
- Chenfang Wang
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - Shijie Zhang
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - Rui Hou
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - Zhongtao Zhao
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - Qian Zheng
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - Qijun Xu
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - Dawei Zheng
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - Guanghui Wang
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Huiquan Liu
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - Xuli Gao
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - Ji-Wen Ma
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - H. Corby Kistler
- USDA ARS Cereal Disease Laboratory, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Zhensheng Kang
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
- * E-mail: (JRX); (ZK)
| | - Jin-Rong Xu
- Purdue-NWAFU Joint Research Center and State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail: (JRX); (ZK)
| |
Collapse
|
18
|
Schneider M, Hsiao HH, Will CL, Giet R, Urlaub H, Lührmann R. Human PRP4 kinase is required for stable tri-snRNP association during spliceosomal B complex formation. Nat Struct Mol Biol 2010; 17:216-21. [PMID: 20118938 DOI: 10.1038/nsmb.1718] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Accepted: 10/09/2009] [Indexed: 11/09/2022]
Abstract
Reversible protein phosphorylation has an essential role during pre-mRNA splicing. Here we identify two previously unidentified phosphoproteins in the human spliceosomal B complex, namely the pre-mRNA processing factors PRP6 and PRP31, both components of the U4/U6-U5 tri-small nuclear ribonucleoprotein (snRNP). We provide evidence that PRP6 and PRP31 are directly phosphorylated by human PRP4 kinase (PRP4K) concomitant with their incorporation into B complexes. Immunodepletion and complementation studies with HeLa splicing extracts revealed that active human PRP4K is required for the phosphorylation of PRP6 and PRP31 and for the assembly of stable, functional B complexes. Thus, the phosphorylation of PRP6 and PRP31 is likely to have a key role during spliceosome assembly. Our data provide new insights into the molecular mechanism by which PRP4K contributes to splicing. They further indicate that numerous phosphorylation events contribute to spliceosome assembly and, thus, that splicing can potentially be modulated at multiple regulatory checkpoints.
Collapse
Affiliation(s)
- Marc Schneider
- Department of Cellular Biochemistry, Max Planck Institute of Biophysical Chemistry, Göttingen, Germany
| | | | | | | | | | | |
Collapse
|
19
|
Lützelberger M, Bottner CA, Schwelnus W, Zock-Emmenthal S, Razanau A, Käufer NF. The N-terminus of Prp1 (Prp6/U5-102 K) is essential for spliceosome activation in vivo. Nucleic Acids Res 2009; 38:1610-22. [PMID: 20007600 PMCID: PMC2836577 DOI: 10.1093/nar/gkp1155] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The spliceosomal protein Prp1 (Prp6/U5-102 K) is necessary for the integrity of pre-catalytic spliceosomal complexes. We have identified a novel regulatory function for Prp1. Expression of mutations in the N-terminus of Prp1 leads to the accumulation of pre-catalytic spliceosomal complexes containing the five snRNAs U1, U2, U5 and U4/U6 and pre-mRNAs. The mutations in the N-terminus, which prevent splicing to occur, include in vitro and in vivo identified phosphorylation sites of Prp4 kinase. These sites are highly conserved in the human ortholog U5-102 K. The results presented here demonstrate that structural integrity of the N-terminus is required to mediate a splicing event, but is not necessary for the assembly of spliceosomes.
Collapse
Affiliation(s)
- Martin Lützelberger
- Institute of Genetics, University of Braunschweig TU, Spielmannstr. 7, 38106 Braunschweig, Germany
| | | | | | | | | | | |
Collapse
|
20
|
Newo ANS, Lützelberger M, Bottner CA, Wehland J, Wissing J, Jänsch L, Käufer NF. Proteomic analysis of the U1 snRNP of Schizosaccharomyces pombe reveals three essential organism-specific proteins. Nucleic Acids Res 2007; 35:1391-401. [PMID: 17264129 PMCID: PMC1865046 DOI: 10.1093/nar/gkl1144] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Characterization of spliceosomal complexes in the fission yeast Schizosaccharomyces pombe revealed particles sedimenting in the range of 30-60S, exclusively containing U1 snRNA. Here, we report the tandem affinity purification (TAP) of U1-specific protein complexes. The components of the complexes were identified using (LC-MS/MS) mass spectrometry. The fission yeast U1 snRNP contains 16 proteins, including the 7 Sm snRNP core proteins. In both fission and budding yeast, the U1 snRNP contains 9 and 10 U1 specific proteins, respectively, whereas the U1 particle found in mammalian cells contains only 3. Among the U1-specific proteins in S. pombe, three are homolog to the mammalian and six to the budding yeast Saccharomyces cerevisiae U1-specific proteins, whereas three, called U1H, U1J and U1L, are proteins specific to S. pombe. Furthermore, we demonstrate that the homolog of U1-70K and the three proteins specific to S. pombe are essential for growth. We will discuss the differences between the U1 snRNPs with respect to the organism-specific proteins found in the two yeasts and the resulting effect it has on pre-mRNA splicing.
Collapse
Affiliation(s)
- Alain N. S. Newo
- Institute of Genetics, Technical University of Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany and Helmholtz Center for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany
| | - Martin Lützelberger
- Institute of Genetics, Technical University of Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany and Helmholtz Center for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany
| | - Claudia A. Bottner
- Institute of Genetics, Technical University of Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany and Helmholtz Center for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany
| | - Jürgen Wehland
- Institute of Genetics, Technical University of Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany and Helmholtz Center for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany
| | - Josef Wissing
- Institute of Genetics, Technical University of Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany and Helmholtz Center for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany
| | - Lothar Jänsch
- Institute of Genetics, Technical University of Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany and Helmholtz Center for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany
| | - Norbert F. Käufer
- Institute of Genetics, Technical University of Braunschweig, Spielmannstr. 7, 38106 Braunschweig, Germany and Helmholtz Center for Infection Research, Inhoffenstr. 7, 38124 Braunschweig, Germany
- *To whom correspondence should be addressed. +49 531 391 5774+49 531 391 5765
| |
Collapse
|
21
|
Bottner CA, Schmidt H, Vogel S, Michele M, Käufer NF. Multiple genetic and biochemical interactions of Brr2, Prp8, Prp31, Prp1 and Prp4 kinase suggest a function in the control of the activation of spliceosomes in Schizosaccharomyces pombe. Curr Genet 2005; 48:151-61. [PMID: 16133344 DOI: 10.1007/s00294-005-0013-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 07/05/2005] [Accepted: 07/12/2005] [Indexed: 10/25/2022]
Abstract
The spliceosomal component Prp1 (U5-102 kD) is found in Schizosaccharomyces pombe, a physiological substrate of Prp4 kinase. Here, we identify, spp41-1, a previously isolated extragenic suppressor of Prp4 kinase. The gene encodes an ATP-dependent RNA helicase homologous to the splicing factor Brr2 of Saccharomyces cerevisiae and U5-200 kD of mammalia. The suppressor allele, spp41-1, interacts genetically with alleles of prp1. We show that Prp1 and Brr2 are complexed in vivo with spliceosomal particles containing the five snRNAs U1, U2, U5, and base-paired U4/U6. Prp1 was found exclusively in small ribonucleoprotein particle (snRNP) complexes sedimenting in the range of 30S-60S, whereas Brr2 was also found sedimenting lower than 30S and free of snRNAs. Moreover, we find that the splicing factor Prp31 is complexed with Prp1 in the same spliceosomal particles containing the five snRNAs. These data indicate that in fission yeast spliceosomal particles larger than 30S exist, which can be considered as pre-catalytic spliceosomes. In addition, we show that S. pombe cells lacking Prp1 still contain these large pre-catalytic spliceosomal particles associated with Prp31. These data are consistent with the notion that in fission yeast phosphorylation of Prp1 by Prp4 kinase is involved in the activation of pre-catalytic spliceosomes.
Collapse
Affiliation(s)
- Claudia A Bottner
- Institute of Genetics, Technical University of Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | | | | | | | | |
Collapse
|
22
|
Makarova OV, Makarov EM, Urlaub H, Will CL, Gentzel M, Wilm M, Lührmann R. A subset of human 35S U5 proteins, including Prp19, function prior to catalytic step 1 of splicing. EMBO J 2004; 23:2381-91. [PMID: 15175653 PMCID: PMC423283 DOI: 10.1038/sj.emboj.7600241] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Accepted: 04/27/2004] [Indexed: 11/09/2022] Open
Abstract
During catalytic activation of the spliceosome, snRNP remodeling events occur, leading to the formation of a 35S U5 snRNP that contains a large group of proteins, including Prp19 and CDC5, not found in 20S U5 snRNPs. To investigate the function of 35S U5 proteins, we immunoaffinity purified human spliceosomes that had not yet undergone catalytic activation (designated BDeltaU1), which contained U2, U4, U5, and U6, but lacked U1 snRNA. Comparison of the protein compositions of BDeltaU1 and activated B* spliceosomes revealed that, whereas U4/U6 snRNP proteins are stably associated with BDeltaU1 spliceosomes, 35S U5-associated proteins (which are present in B*) are largely absent, suggesting that they are dispensable for complex B formation. Indeed, immunodepletion/complementation experiments demonstrated that a subset of 35S U5 proteins including Prp19, which form a stable heteromeric complex, are required prior to catalytic step 1 of splicing, but not for stable integration of U4/U6.U5 tri-snRNPs. Thus, comparison of the proteomes of spliceosomal complexes at defined stages can provide information as to which proteins function as a group at a particular step of splicing.
Collapse
Affiliation(s)
- Olga V Makarova
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Evgeny M Makarov
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Henning Urlaub
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Cindy L Will
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Marc Gentzel
- EMBL, Bioanalytical Research Group, Heidelberg, Germany
| | - Matthias Wilm
- EMBL, Bioanalytical Research Group, Heidelberg, Germany
| | - Reinhard Lührmann
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany. Tel.: +49 551 201 1407; Fax: +49 551 201 1197; E-mail:
| |
Collapse
|
23
|
Sun X, Zhang H, Wang D, Ma D, Shen Y, Shang Y. DLP, a novel Dim1 family protein implicated in pre-mRNA splicing and cell cycle progression. J Biol Chem 2004; 279:32839-47. [PMID: 15161931 DOI: 10.1074/jbc.m402522200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In eukaryotes, primary transcripts undergo a splicing process that removes intronic sequences by a macromolecular enzyme known as the spliceosome. Both genetic and biochemical studies have revealed that essential components of the spliceosome include five small RNAs, U1, U2, U4, U5, and U6, and as many as 300 distinct proteins. Here we report the molecular cloning and functional analysis of a novel cDNA encoding for a protein of 149 amino acids. This protein has 38% amino acid sequence identity with and is evolutionally related to yeast Dim1 protein. Hence we named this protein DLP for Dim1-like protein. We showed that DLP is required for S/G(2) transition. We also demonstrated that DLP functions in cell nucleus and interacts with the U5-102-kDa protein subunit of the spliceosome, and blocking DLP protein activity led to an insufficient pre-mRNA splicing, suggesting that DLP is yet another protein component involved in pre-mRNA splicing. Collectively, our experiments indicated that DLP is implicated in not only cell cycle progression but also in a more specific molecular process such as pre-mRNA splicing.
Collapse
MESH Headings
- Alternative Splicing
- Amino Acid Sequence
- Base Sequence
- Blotting, Northern
- Blotting, Western
- Cell Cycle
- Cell Cycle Proteins/chemistry
- Cell Cycle Proteins/metabolism
- Cell Division
- Cell Line, Tumor
- Cell Nucleus/metabolism
- Cloning, Molecular
- Computational Biology
- DNA, Complementary/metabolism
- Genome
- Glutathione Transferase/metabolism
- HeLa Cells
- Humans
- Microscopy, Confocal
- Microscopy, Fluorescence
- Models, Genetic
- Molecular Sequence Data
- Nuclear Proteins
- Phylogeny
- Plasmids/metabolism
- Precipitin Tests
- Protein Binding
- RNA/metabolism
- RNA Splicing
- RNA, Messenger/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Amino Acid
- Spliceosomes/metabolism
- Transfection
- Two-Hybrid System Techniques
Collapse
Affiliation(s)
- Xiaojing Sun
- Department of Biochemistry and Molecular Biology, Peking University Health Science Center, 38 Xue Yuan Road, Beijing 100083, China
| | | | | | | | | | | |
Collapse
|
24
|
Kuhn AN, Käufer NF. Pre-mRNA splicing in Schizosaccharomyces pombe: regulatory role of a kinase conserved from fission yeast to mammals. Curr Genet 2003; 42:241-51. [PMID: 12589463 DOI: 10.1007/s00294-002-0355-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2002] [Revised: 11/05/2002] [Accepted: 11/05/2002] [Indexed: 11/28/2022]
Abstract
Most primary messenger RNA transcripts (pre-mRNAs) in eukaryotes contain intervening sequences that must be precisely removed to generate a functional mRNA. The excision of the intervening sequences, the introns, from a pre-mRNA and the concomitant joining of the flanking sequences, the exons, is called pre-mRNA splicing. Pre-mRNA splicing takes place in large ribonucleoprotein machinery, the spliceosome. Although the function and components of this machinery appear to be highly conserved between organisms, many distinct differences between budding yeast, Saccharomyces cerevisiae, and fission yeast, Schizosaccharomyces pombe, have been found, emphasizing their evolutionary distance. Most interestingly, fission yeast appears to reflect the more conservative evolutionary development regarding pre-mRNA splicing. Many spliceosomal components, including the five small nuclear RNAs, which most likely form the catalytic core of the spliceosome, show a higher degree of similarity with the components of the splicing machinery found in mammals. In addition, several regulatory components of the spliceosome detected in mammals are absent in Sac. cerevisiae, but present in Sch. pombe. Here, we review recent progress made in our understanding of the control of pre-mRNA splicing in Sch. pombe. The focus is on Prp4p kinase, first discovered in fission yeast and also present in mammals, but absent in Sac. cerevisiae. Results from both mammals and Sch. pombe suggest that Prp4p plays a key role in regulating pre-mRNA splicing and in connecting this process with the cell cycle.
Collapse
Affiliation(s)
- Andreas N Kuhn
- Institut für Genetik-Biozentrum, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany.
| | | |
Collapse
|
25
|
Ajuh P, Chusainow J, Ryder U, Lamond AI. A novel function for human factor C1 (HCF-1), a host protein required for herpes simplex virus infection, in pre-mRNA splicing. EMBO J 2002; 21:6590-602. [PMID: 12456665 PMCID: PMC136956 DOI: 10.1093/emboj/cdf652] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Human factor C1 (HCF-1) is needed for the expression of herpes simplex virus 1 (HSV-1) immediate-early genes in infected mammalian cells. Here, we provide evidence that HCF-1 is required for spliceosome assembly and splicing in mammalian nuclear extracts. HCF-1 interacts with complexes containing splicing snRNPs in uninfected mammalian cells and is a stable component of the spliceosome complex. We show that a missense mutation in HCF-1 in the BHK21 hamster cell line tsBN67, at the non-permissive temperature, inhibits the protein's interaction with U1 and U5 splicing snRNPs, causes inefficient spliceosome assembly and inhibits splicing. Transient expression of wild-type HCF-1 in tsBN67 cells restores splicing at the non-permissive temperature. The inhibition of splicing in tsBN67 cells correlates with the temperature-sensitive cell cycle arrest phenotype, suggesting that HCF-1-dependent splicing events may be required for cell cycle progression.
Collapse
Affiliation(s)
| | | | | | - Angus I. Lamond
- School of Life Sciences, The University of Dundee, Dow Street, Dundee DD1 5EH, UK
Corresponding author e-mail:
| |
Collapse
|
26
|
Steen BR, Lian T, Zuyderduyn S, MacDonald WK, Marra M, Jones SJM, Kronstad JW. Temperature-regulated transcription in the pathogenic fungus Cryptococcus neoformans. Genome Res 2002; 12:1386-400. [PMID: 12213776 PMCID: PMC186651 DOI: 10.1101/gr.80202] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The basidiomycete fungus Cryptococcus neoformans is an opportunistic pathogen of worldwide importance that causes meningitis, leading to death in immunocompromised individuals. Unlike many basidiomycete fungi, C. neoformans is thermotolerant, and its ability to grow at 37 degrees C is considered to be a virulence factor. We used serial analysis of gene expression (SAGE) to characterize the transcriptomes of C. neoformans strains that represent two varieties with different polysaccharide capsule serotypes. These include a serotype D strain of the C. neoformans variety neoformans and a serotype A strain of variety grubii. In this report, we describe the construction and characterization of SAGE libraries from each strain grown at 25 degrees C and 37 degrees C. The SAGE data reveal transcriptome differences between the two strains, even at this early stage of analysis, and identify sets of genes with higher transcript levels at 25 degrees C or 37 degrees C. Notably, growth at the lower temperature increased transcript levels for histone genes, indicating a general influence of temperature on chromatin structure. At 37 degrees C, we noted elevated transcript levels for several genes encoding heat shock proteins and translation machinery. Some of these genes may play a role in temperature-regulated phenotypes in C. neoformans, such as the adaptation of the fungus to growth in the host and the dimorphic transition between budding and filamentous growth. Overall, this work provides the most comprehensive gene expression data available for C. neoformans; this information will be a critical resource both for gene discovery and genome annotation in this pathogen.
Collapse
Affiliation(s)
- Barbara R Steen
- Biotechnology Laboratory, Department of Microbiology and Immunology, and Faculty of Agricultural Sciences, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | | | | | | | | | | | | |
Collapse
|
27
|
Chung S, Zhou Z, Huddleston KA, Harrison DA, Reed R, Coleman TA, Rymond BC. Crooked neck is a component of the human spliceosome and implicated in the splicing process. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1576:287-97. [PMID: 12084575 DOI: 10.1016/s0167-4781(02)00368-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Drosophila crooked neck (crn) gene is essential for embryogenesis and has been implicated in cell cycle progression and in pre-mRNA splicing although a direct role in either process has not been established. Here we report isolation of the human crooked neck homolog, HCRN, and provide evidence for its function in splicing. HCRN encodes an unusual protein composed largely of tetratricopeptide repeat (TPR) elements. The crooked neck protein co-localizes with the SR and Sm protein splicing factors in discrete subnuclear domains implicated in snRNP biogenesis. In vitro assembly experiments show that an 83 kDa hcrn isoform is stably recruited to splicing complexes coincident with the addition of the U4/U6.U5 tri-snRNP particle. Crooked neck activity appears essential as extracts depleted of hcrn fail to splice pre-mRNA. These and related data support the view that crooked neck is a phylogenetically conserved pre-mRNA splicing factor.
Collapse
Affiliation(s)
- Seyung Chung
- T.H. Morgan School of Biological Sciences, University of Kentucky, Lexington, KY 40506, USA
| | | | | | | | | | | | | |
Collapse
|
28
|
Dellaire G, Makarov EM, Cowger JJM, Longman D, Sutherland HGE, Lührmann R, Torchia J, Bickmore WA. Mammalian PRP4 kinase copurifies and interacts with components of both the U5 snRNP and the N-CoR deacetylase complexes. Mol Cell Biol 2002; 22:5141-56. [PMID: 12077342 PMCID: PMC139773 DOI: 10.1128/mcb.22.14.5141-5156.2002] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
A growing body of evidence supports the coordination of pre-mRNA processing and transcriptional regulation. We demonstrate here that mammalian PRP4 kinase (PRP4K) is associated with complexes involved in both of these processes. PRP4K is implicated in pre-mRNA splicing as the homologue of the Schizosaccharomyces pombe pre-mRNA splicing kinase Prp4p, and it is enriched in SC35-containing nuclear splicing speckles. RNA interference of Caenorhabditis elegans PRP4K indicates that it is essential in metazoans. In support of a role for PRP4K in pre-mRNA splicing, we identified PRP6, SWAP, and pinin as interacting proteins and demonstrated that PRP4K is a U5 snRNP-associated kinase. In addition, BRG1 and N-CoR, components of nuclear hormone coactivator and corepressor complexes, also interact with PRP4K. PRP4K coimmunoprecipitates with N-CoR, BRG1, pinin, and PRP6, and we present data suggesting that PRP6 and BRG1 are substrates of this kinase. Lastly, PRP4K, BRG1, and PRP6 can be purified as components of the N-CoR-2 complex, and affinity-purified PRP4K/N-CoR complexes exhibit deacetylase activity. We suggest that PRP4K is an essential kinase that, in association with the both U5 snRNP and N-CoR deacetylase complexes, demonstrates a possible coordination of pre-mRNA splicing with chromatin remodeling events involved in transcriptional regulation.
Collapse
Affiliation(s)
- Graham Dellaire
- MRC-Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, Scotland, UK
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Dagher SF, Fu XD. Evidence for a role of Sky1p-mediated phosphorylation in 3' splice site recognition involving both Prp8 and Prp17/Slu4. RNA (NEW YORK, N.Y.) 2001; 7:1284-97. [PMID: 11565750 PMCID: PMC1370172 DOI: 10.1017/s1355838201016077] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The SRPK family of kinases is specific for RS domain-containing splicing factors and known to play a critical role in protein-protein interaction and intracellular distribution of their substrates in both yeast and mammalian cells. However, the function of these kinases in pre-mRNA splicing remains unclear. Here we report that SKY1, a SRPK family member in Saccharomyces cerevisiae, genetically interacts with PRP8 and PRP17/SLU4, both of which are involved in splice site selection during pre-mRNA splicing. Prp8 is essential for splicing and is known to interact with both 5' and 3' splice sites in the spliceosomal catalytic center, whereas Prp17/Slu4 is nonessential and is required only for efficient recognition of the 3' splice site. Interestingly, deletion of SKY1 was synthetically lethal with all prp17 mutants tested, but only with specific prp8 alleles in a domain implicated in governing fidelity of 3'AG recognition. Indeed, deletion of SKY1 specifically suppressed 3'AG mutations in ACT1-CUP1 splicing reporters. These results suggest for the first time that 3' AG recognition may be subject to phosphorylation regulation by Sky1p during pre-mRNA splicing.
Collapse
Affiliation(s)
- S F Dagher
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla 92093-0651, USA
| | | |
Collapse
|
30
|
Kojima T, Zama T, Wada K, Onogi H, Hagiwara M. Cloning of human PRP4 reveals interaction with Clk1. J Biol Chem 2001; 276:32247-56. [PMID: 11418604 DOI: 10.1074/jbc.m103790200] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prp4 is a protein kinase of Schizosaccharomyces pombe identified through its role in pre-mRNA splicing, and belongs to a kinase family including mammalian serine/arginine-rich protein-specific kinases and Clks, whose substrates are serine/arginine-rich proteins. We cloned human PRP4 (hPRP4) full-length cDNA and the antiserum raised against a partial peptide of hPRP4 recognized 170-kDa polypeptide in HeLa S3 cell extracts. Northern blot analysis revealed that hPRP4 mRNA was ubiquitously expressed in multiple tissues. The extended NH(2)-terminal region of hPRP4 contains an arginine/serine-rich domain and putative nuclear localization signals. hPRP4 phosphorylated and interacted with SF2/ASF, one of the essential splicing factors. Indirect immunofluorescence analysis revealed that endogenous hPRP4 was distributed in a nuclear speckled pattern and colocalized with SF2/ASF in HeLa S3 cells. Furthermore, hPRP4 interacted directly with Clk1 on its COOH terminus, and the arginine/serine-rich domain of hPRP4 was phosphorylated by Clk1 in vitro. Overexpression of Clk1 caused redistribution of hPRP4, from the speckled to the diffuse pattern in nucleoplasm, whereas inactive mutant of Clk1 caused no change of hPRP4 localization. These findings suggest that the NH(2)-terminal region of hPRP4 may play regulatory roles under an unidentified signal transduction pathway through Clk1.
Collapse
Affiliation(s)
- T Kojima
- Department of Functional Genomics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | | | | | | | | |
Collapse
|
31
|
Current Awareness. Yeast 2001. [DOI: 10.1002/yea.685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
|