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Zhu X, Ni P, Sturrock M, Wang Y, Ding J, Chang Y, Hu J, Bao Z. Fine-mapping and association analysis of candidate genes for papilla number in sea cucumber, Apostichopus japonicus. MARINE LIFE SCIENCE & TECHNOLOGY 2022; 4:343-355. [PMID: 37073167 PMCID: PMC10077181 DOI: 10.1007/s42995-022-00139-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 06/03/2022] [Indexed: 05/03/2023]
Abstract
The papilla number is one of the most economically important traits of sea cucumber in the China marketing trade. However, the genetic basis for papilla number diversity in holothurians is still scarce. In the present study, we conducted genome-wide association studies (GWAS) for the trait papilla number of sea cucumbers utilizing a set of 400,186 high-quality SNPs derived from 200 sea cucumbers. Two significant trait-associated SNPs that passed Bonferroni correction (P < 1.25E-7) were located in the intergenic region near PATS1 and the genic region of EIF4G, which were reported to play a pivotal role in cell growth and proliferation. The fine-mapping regions around the top two lead SNPs provided precise causative loci/genes related to papilla formation and cellular activity, including PPP2R3C, GBP1, and BCAS3. Potential SNPs with P < 1E-4 were acquired for the following GO and KEGG enrichment analysis. Moreover, the two lead SNPs were verified in another population of sea cucumber, and the expressive detection of three potential candidate genes PATS1, PPP2R3C, and EIF4G that near or cover the two lead SNPs was conducted in papilla tissue of TG (Top papilla number group) and BG (Bottom papilla number group) by qRT-PCR. We found the significantly higher expression profile of PATS1 (3.34-fold), PPP2R3C (4.90-fold), and EIF4G (4.23-fold) in TG, implying their potential function in papilla polymorphism. The present results provide valuable information to decipher the phenotype differences of the papilla trait and will provide a scientific basis for selective breeding in sea cucumbers. Supplementary Information The online version contains supplementary material available at 10.1007/s42995-022-00139-w.
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Affiliation(s)
- Xinghai Zhu
- Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003 China
| | - Ping Ni
- Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003 China
| | - Marc Sturrock
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, D02 YN77 Ireland
| | - Yangfan Wang
- Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003 China
| | - Jun Ding
- College of Fisheries and Life Science, Dalian Ocean University, Dalian, 116023 China
| | - Yaqing Chang
- College of Fisheries and Life Science, Dalian Ocean University, Dalian, 116023 China
| | - Jingjie Hu
- Laboratory of Tropical Marine Germplasm Resources and Breeding Engineering, Sanya Oceanographic Institution, Ocean University of China, Sanya, 572000 China
| | - Zhenmin Bao
- Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003 China
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Altunoglu U, Börklü E, Shukla A, Escande-Beillard N, Ledig S, Azaklı H, Nayak SS, Eraslan S, Girisha KM, Kennerknecht I, Kayserili H. Expanding the spectrum of syndromic PPP2R3C-related XY gonadal dysgenesis to XX gonadal dysgenesis. Clin Genet 2021; 101:221-232. [PMID: 34750818 DOI: 10.1111/cge.14086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/20/2021] [Accepted: 11/04/2021] [Indexed: 01/09/2023]
Abstract
Homozygous variants in PPP2R3C have been reported to cause a syndromic 46,XY complete gonadal dysgenesis phenotype with extragonadal manifestations (GDRM, MIM# 618419) in patients from four unrelated families, whereas heterozygous variants have been linked to reduced fertility with teratozoospermia (SPGF36, MIM# 618420) in male carriers. We present eight patients from four unrelated families of Turkish and Indian descent with three different germline homozygous PPP2R3C variants including a novel in-frame duplication (c.639_647dupTTTCTACTC, p.Ser216_Tyr218dup). All patients exhibit recognizable facial dysmorphisms allowing gestalt diagnosis. In two 46,XX patients with hypergonadotropic hypogonadism and nonvisualized gonads, primary amenorrhea along with absence of secondary sexual characteristics and/or unique facial gestalt led to the diagnosis. 46,XY affected individuals displayed a spectrum of external genital phenotypes from ambiguous genitalia to complete female. We expand the spectrum of syndromic PPP2R3C-related XY gonadal dysgenesis to both XY and XX gonadal dysgenesis. Our findings supported neither ocular nor muscular involvement as major criteria of the syndrome. We also did not encounter infertility problems in the carriers. Since both XX and XY individuals were affected, we hypothesize that PPP2R3C is essential in the early signaling cascades controlling sex determination in humans.
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Affiliation(s)
- Umut Altunoglu
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey.,Medical Genetics Department, Istanbul University Istanbul Medical School, Istanbul, Turkey
| | - Esra Börklü
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Nathalie Escande-Beillard
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey.,Institute of Medical Biology, A*STAR, Singapore, Singapore
| | - Susanne Ledig
- Institut für Humangenetik, Westfaelische Wilhelms-Universitaet Muenster, Muenster, Germany
| | - Hülya Azaklı
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey
| | - Shalini S Nayak
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Serpil Eraslan
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey
| | - Katta Mohan Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Ingo Kennerknecht
- Institut für Humangenetik, Westfaelische Wilhelms-Universitaet Muenster, Muenster, Germany
| | - Hülya Kayserili
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey.,Medical Genetics Department, Istanbul University Istanbul Medical School, Istanbul, Turkey
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Dörner MF, Boknik P, Köpp F, Buchwalow IB, Neumann J, Gergs U. Mechanisms of Systolic Cardiac Dysfunction in PP2A, PP5 and PP2AxPP5 Double Transgenic Mice. Int J Mol Sci 2021; 22:ijms22179448. [PMID: 34502355 PMCID: PMC8431312 DOI: 10.3390/ijms22179448] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 12/15/2022] Open
Abstract
As part of our ongoing studies on the potential pathophysiological role of serine/threonine phosphatases (PP) in the mammalian heart, we have generated transgenic mice with cardiac muscle cell-specific overexpression of PP2Acα (PP2A) and PP5 (PP5). For further studies we crossbred PP2A and PP5 mice to obtain PP2AxPP5 double transgenic mice (PP2AxPP5, DT) and compared them with littermate wild-type mice (WT) serving as a control. The mortality of DT mice was greatly enhanced vs. other genotypes. Cardiac fibrosis was noted histologically and mRNA levels of collagen 1α, collagen 3α and fibronectin 1 were augmented in DT. DT and PP2A mice exhibited an increase in relative heart weight. The ejection fraction (EF) was reduced in PP2A and DT but while the EF of PP2A was nearly normalized after β-adrenergic stimulation by isoproterenol, it was almost unchanged in DT. Moreover, left atrial preparations from DT were less sensitive to isoproterenol treatment both under normoxic conditions and after hypoxia. In addition, levels of the hypertrophy markers atrial natriuretic peptide and B-type natriuretic peptide as well as the inflammation markers interleukin 6 and nuclear factor kappa B were increased in DT. PP2A enzyme activity was enhanced in PP2A vs. WT but similar to DT. This was accompanied by a reduced phosphorylation state of phospholamban at serine-16. Fittingly, the relaxation times in left atria from DT were prolonged. In summary, cardiac co-overexpression of PP2A and PP5 were detrimental to animal survival and cardiac function, and the mechanism may involve dephosphorylation of important regulatory proteins but also fibrosis and inflammation.
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Affiliation(s)
- Mara-Francine Dörner
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097 Halle, Germany; (M.-F.D.); (F.K.); (J.N.)
- Mibe GmbH Arzneimittel, D-06796 Brehna, Germany
| | - Peter Boknik
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Westfälische Wilhelms-Universität, D-48149 Münster, Germany;
| | - Friedrich Köpp
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097 Halle, Germany; (M.-F.D.); (F.K.); (J.N.)
| | - Igor B. Buchwalow
- Institute for Hematopathology, Fangdieckstr. 75a, D-22547 Hamburg, Germany;
| | - Joachim Neumann
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097 Halle, Germany; (M.-F.D.); (F.K.); (J.N.)
| | - Ulrich Gergs
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097 Halle, Germany; (M.-F.D.); (F.K.); (J.N.)
- Correspondence: ; Tel.: +49-345-557-4093
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Protein Phosphatase 2A (PP2A) mutations in brain function, development, and neurologic disease. Biochem Soc Trans 2021; 49:1567-1588. [PMID: 34241636 DOI: 10.1042/bst20201313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/09/2021] [Accepted: 06/11/2021] [Indexed: 12/15/2022]
Abstract
By removing Ser/Thr-specific phosphorylations in a multitude of protein substrates in diverse tissues, Protein Phosphatase type 2A (PP2A) enzymes play essential regulatory roles in cellular signalling and physiology, including in brain function and development. Here, we review current knowledge on PP2A gene mutations causally involved in neurodevelopmental disorders and intellectual disability, focusing on PPP2CA, PPP2R1A and PPP2R5D. We provide insights into the impact of these mutations on PP2A structure, substrate specificity and potential function in neurobiology and brain development.
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Neumann J, Boknik P, Kirchhefer U, Gergs U. The role of PP5 and PP2C in cardiac health and disease. Cell Signal 2021; 85:110035. [PMID: 33964402 DOI: 10.1016/j.cellsig.2021.110035] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/16/2021] [Accepted: 05/03/2021] [Indexed: 02/08/2023]
Abstract
Protein phosphatases are important, for example, as functional antagonists of β-adrenergic stimulation of the mammalian heart. While β-adrenergic stimulations increase the phosphorylation state of regulatory proteins and therefore force of contraction in the heart, these phosphorylations are reversed and thus force is reduced by the activity of protein phosphatases. In this context the role of PP5 and PP2C is starting to unravel. They do not belong to the same family of phosphatases with regard to sequence homology, many similarities with regard to location, activation by lipids and putative substrates have been worked out over the years. We also suggest which pathways for regulation of PP5 and/or PP2C described in other tissues and not yet in the heart might be useful to look for in cardiac tissue. Both phosphatases might play a role in signal transduction of sarcolemmal receptors in the heart. Expression of PP5 and PP2C can be increased by extracellular stimuli in the heart. Because PP5 is overexpressed in failing animal and human hearts, and because overexpression of PP5 or PP2C leads to cardiac hypertrophy and KO of PP5 leads to cardiac hypotrophy, one might argue for a role of PP5 and PP2C in heart failure. Because PP5 and PP2C can reduce, at least in vitro, the phosphorylation state of proteins thought to be relevant for cardiac arrhythmias, a role of these phosphatases for cardiac arrhythmias is also probable. Thus, PP5 and PP2C might be druggable targets to treat important cardiac diseases like heart failure, cardiac hypertrophy and cardiac arrhythmias.
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Affiliation(s)
- Joachim Neumann
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Magdeburger Str. 4, D-06097 Halle, Germany.
| | - Peter Boknik
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Westfälische Wilhelms-Universität, Domagkstraße 12, D-48149 Münster, Germany.
| | - Uwe Kirchhefer
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Westfälische Wilhelms-Universität, Domagkstraße 12, D-48149 Münster, Germany.
| | - Ulrich Gergs
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Magdeburger Str. 4, D-06097 Halle, Germany.
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Elias AE, Kun B, Sabula IMC, Golomb-Mello G, Cespedes Zablah A, Kreiling JA. The mir-465 family is upregulated with age and attenuates growth hormone signaling in mouse liver. Aging Cell 2019; 18:e12892. [PMID: 30637918 PMCID: PMC6413667 DOI: 10.1111/acel.12892] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/13/2018] [Accepted: 11/27/2018] [Indexed: 12/13/2022] Open
Abstract
We analyzed the small RNA transcriptome from 5‐month‐old, 24‐month‐old, and 36‐month‐old mouse liver and found 56 miRNAs that changed their expression profile with age. Among these is a cluster of 18 miRNAs that are upregulated between 50‐ and 1,000‐fold at 24 and 36 months of age. This cluster is located in a 60‐kb region of the X‐chromosome that is devoid of other coding sequences and is part of a lamin‐associated domain. Potential targets of the miRNAs in the cluster suggest they may regulate several pathways altered in aging, including the PI3K‐Akt pathway. Total transcriptome analyses indicate that expression of several potential genes in the PI3K‐Akt pathway that may be targeted by the mir‐465 family (mmu‐mir‐465a, mmu‐mir‐465b, and mmu‐mir‐465c) is downregulated with age. Transfection of the liver cell line AML12 with mir‐465 family members leads to a reduction of three of these potential targets at the mRNA level: a 40% reduction of the growth hormone receptor (GHR), and a 25% reduction in Kitl and PPP2R3C. Further investigation of the GHR 3′UTR revealed that the mir‐465 family directly targets the GHR mRNA. Cells transfected with mir‐465 showed a reduction of JAK2 and STAT5 phosphorylation upon growth hormone (GH) stimulation, resulting in a reduction in insulin‐like growth factor 1 (IGF‐1) and IGF‐1‐binding protein 3 expression. With age, GH signaling falls and there is a reduction in circulating IGF‐1. Our data suggest that an increase in expression of the mir‐465 family with age may contribute to the reduction in the GH signaling.
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Affiliation(s)
- Amy E. Elias
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown Center on the Biology of Aging; Brown University; Providence Rhode Island
| | - Bianca Kun
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown Center on the Biology of Aging; Brown University; Providence Rhode Island
| | - Ian M. C. Sabula
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown Center on the Biology of Aging; Brown University; Providence Rhode Island
| | - Gail Golomb-Mello
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown Center on the Biology of Aging; Brown University; Providence Rhode Island
| | - Andrea Cespedes Zablah
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown Center on the Biology of Aging; Brown University; Providence Rhode Island
| | - Jill A. Kreiling
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown Center on the Biology of Aging; Brown University; Providence Rhode Island
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Physiologic functions of PP2A: Lessons from genetically modified mice. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:31-50. [DOI: 10.1016/j.bbamcr.2018.07.010] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 07/11/2018] [Accepted: 07/14/2018] [Indexed: 01/03/2023]
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8
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Alvarado ME, Rubiano C, Sánchez W, Díaz A, Wasserman M. Calcium-binding proteins that are type B″ regulatory subunits of phosphatase 2A in Giardia intestinalis. Parasitol Res 2018; 117:3205-3214. [PMID: 30043281 DOI: 10.1007/s00436-018-6019-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/17/2018] [Indexed: 10/28/2022]
Abstract
Giardia intestinalis is a protozoan parasite that colonizes the upper part of the small intestine of its mammalian hosts. The trophozoite, which is the replicative stage, has a complex cytoskeleton that allows it to move and adhere to intestinal cells. It has been proposed that protein phosphatase 2A (PP2A) participates in the regulation of changes to the parasite cytoskeleton during its life cycle. However, how PP2A is involved in this regulation remains unclear since its substrates and regulators have not been characterized. In this work, we report the bioinformatic and experimental analysis of two potential regulatory B″ subunits of PP2A in Giardia, both of which are calcium-binding proteins. In this work, in silico and experimental evidence of the binding of both proteins to calcium is presented; the proteins are shown to interact with the catalytic PP2A subunit in the trophozoite stage, and they exhibit different subcellular localization patterns. Because PP2A is a heterotrimer, homology analysis of the different subunits of PP2A indicates that fewer holoenzyme combinations can be formed in this parasite than in other organisms. Our results suggest that the localization of PP2A may be associated with calcium-dependent signaling through its B″ type regulatory subunits.
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Affiliation(s)
- Magda E Alvarado
- Laboratorio de Investigaciones Básicas en Bioquímica - LIBBIQ, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia.
| | - Claudia Rubiano
- Laboratorio de Investigaciones Básicas en Bioquímica - LIBBIQ, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
| | - William Sánchez
- Laboratorio de Investigaciones Básicas en Bioquímica - LIBBIQ, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Andrea Díaz
- Laboratorio de Investigaciones Básicas en Bioquímica - LIBBIQ, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Moisés Wasserman
- Laboratorio de Investigaciones Básicas en Bioquímica - LIBBIQ, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
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Sakaguchi N, Maeda K. Germinal Center B-Cell-Associated Nuclear Protein (GANP) Involved in RNA Metabolism for B Cell Maturation. Adv Immunol 2016; 131:135-86. [PMID: 27235683 DOI: 10.1016/bs.ai.2016.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Germinal center B-cell-associated nuclear protein (GANP) is upregulated in germinal center B cells against T-cell-dependent antigens in mice and humans. In mice, GANP depletion in B cells impairs antibody affinity maturation. Conversely, its transgenic overexpression augments the generation of high-affinity antigen-specific B cells. GANP associates with AID in the cytoplasm, shepherds AID into the nucleus, and augments its access to the rearranged immunoglobulin (Ig) variable (V) region of the genome in B cells, thereby precipitating the somatic hypermutation of V region genes. GANP is also upregulated in human CD4(+) T cells and is associated with APOBEC3G (A3G). GANP interacts with A3G and escorts it to the virion cores to potentiate its antiretroviral activity by inactivating HIV-1 genomic cDNA. Thus, GANP is characterized as a cofactor associated with AID/APOBEC cytidine deaminase family molecules in generating diversity of the IgV region of the genome and genetic alterations of exogenously introduced viral targets. GANP, encoded by human chromosome 21, as well as its mouse equivalent on chromosome 10, contains a region homologous to Saccharomyces Sac3 that was characterized as a component of the transcription/export 2 (TREX-2) complex and was predicted to be involved in RNA export and metabolism in mammalian cells. The metabolism of RNA during its maturation, from the transcription site at the chromosome within the nucleus to the cytoplasmic translation apparatus, needs to be elaborated with regard to acquired and innate immunity. In this review, we summarize the current knowledge on GANP as a component of TREX-2 in mammalian cells.
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Affiliation(s)
- N Sakaguchi
- WPI Immunology Frontier Research Center (IFReC), Osaka University, Suita, Osaka, Japan; Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
| | - K Maeda
- WPI Immunology Frontier Research Center (IFReC), Osaka University, Suita, Osaka, Japan; Laboratory of Host Defense, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
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Kitabatake M, Soma M, Zhang T, Kuwahara K, Fukushima Y, Nojima T, Kitamura D, Sakaguchi N. JNK regulatory molecule G5PR induces IgG autoantibody-producing plasmablasts from peritoneal B1a cells. THE JOURNAL OF IMMUNOLOGY 2015; 194:1480-8. [PMID: 25601926 DOI: 10.4049/jimmunol.1401127] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Peritoneal B1a cells expressing CD5 and CD11b generate autoantibody-producing precursors in autoimmune-prone mice. Previous studies show reduced JNK signaling in peritoneal B1a cells of female New Zealand Black mice and an abnormal increase of protein phosphatase 2A subunit G5PR that regulates BCR-mediated JNK signaling as a cause of autoimmunity. To investigate the mechanism regulating B1a differentiation into autoantibody-secreting plasmablasts (PBs), we applied an in vitro culture system that supports long-term growth of germinal center (GC) B cells (iGB) with IL-4, CD40L, and BAFF. Compared with spleen B2 cells, B1a cells differentiated into GC-like B cells, but more markedly into PBs, and underwent class switching toward IgG1. During iGB culture, B1a cells expressed GC-associated aicda, g5pr, and bcl6, and markedly PB-associated prdm1, irf4, and xbp1. B1a-derived iGB cells from New Zealand Black × New Zealand White F1 mice highly differentiated into autoantibody-secreting PBs in vitro and localized to the GC area in vivo. In iGB culture, JNK inhibitor SP600125 augmented the differentiation of C57BL/6 B1a cells into PBs. Furthermore, B1a cells from G5PR transgenic mice markedly differentiated into IgM and IgG autoantibody-secreting PBs. In conclusion, JNK regulation is critical to suppress autoantibody-secreting PBs from peritoneal B1a cells.
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Affiliation(s)
- Masahiro Kitabatake
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Miho Soma
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Tianli Zhang
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Kazuhiko Kuwahara
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Yoshimi Fukushima
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Takuya Nojima
- Division of Molecular Biology, Research Institute for Biomedical Sciences, Tokyo University of Science, Chiba 278-0022, Japan; and
| | - Daisuke Kitamura
- Division of Molecular Biology, Research Institute for Biomedical Sciences, Tokyo University of Science, Chiba 278-0022, Japan; and
| | - Nobuo Sakaguchi
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
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Abstract
Protein phosphatases of the type 2A family (PP2A) represent a major fraction of cellular Ser/Thr phosphatase activity in any given human tissue. In this review, we describe how the holoenzymic nature of PP2A and the existence of several distinct PP2A composing subunits allow for the generation of multiple structurally and functionally different PP2A complexes, explaining why PP2A is involved in the regulation of so many diverse cell biological and physiological processes. Moreover, in human disease, most notably in several cancers and Alzheimer's Disease, PP2A expression and/or activity have been found significantly decreased, underscoring its important functions as a major tumor suppressor and tau phosphatase. Hence, several recent preclinical studies have demonstrated that pharmacological restoration of PP2A activity, as well as pharmacological PP2A inhibition, under certain conditions, may be of significant future therapeutic value.
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12
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Poole E, Bain M, Teague L, Takei Y, Laskey R, Sinclair J. The cellular protein MCM3AP is required for inhibition of cellular DNA synthesis by the IE86 protein of human cytomegalovirus. PLoS One 2012; 7:e45686. [PMID: 23094019 PMCID: PMC3477159 DOI: 10.1371/journal.pone.0045686] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 08/24/2012] [Indexed: 11/18/2022] Open
Abstract
Like all DNA viruses, human cytomegalovirus (HCMV) infection is known to result in profound effects on host cell cycle. Infection of fibroblasts with HCMV is known to induce an advance in cell cycle through the G0-G1 phase and then a subsequent arrest of cell cycle in early S-phase, presumably resulting in a cellular environment optimum for high levels of viral DNA replication whilst precluding replication of cellular DNA. Although the exact mechanisms used to arrest cell cycle by HCMV are unclear, they likely involve a number of viral gene products and evidence points to the ability of the virus to prevent licensing of cellular DNA synthesis. One viral protein known to profoundly alter cell cycle is the viral immediate early 86 (IE86) protein - an established function of which is to initially drive cells into early S phase but then inhibit cellular DNA synthesis. Here we show that, although IE86 interacts with the cellular licensing factor Cdt1, it does not inhibit licensing of cellular origins. Instead, IE86-mediated inhibition of cellular DNA synthesis requires mini-chromosome-maintenance 3 (MCM3) associated protein (MCM3AP), which can cause subsequent inhibition of initiation of cellular DNA synthesis in a licensing-independent manner.
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Affiliation(s)
- Emma Poole
- Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Mark Bain
- Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Linda Teague
- Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Yoshinori Takei
- Hutchison/MRC Research Centre, University of Cambridge, Cambridge, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Ron Laskey
- Hutchison/MRC Research Centre, University of Cambridge, Cambridge, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - John Sinclair
- Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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Kitabatake M, Toda T, Kuwahara K, Igarashi H, Ohtsuji M, Tsurui H, Hirose S, Sakaguchi N. Transgenic overexpression of G5PR that is normally augmented in centrocytes impairs the enrichment of high-affinity antigen-specific B cells, increases peritoneal B-1a cells, and induces autoimmunity in aged female mice. THE JOURNAL OF IMMUNOLOGY 2012; 189:1193-201. [PMID: 22753944 DOI: 10.4049/jimmunol.1102774] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To investigate signals that control B cell selection, we examined expression of G5PR, a regulatory subunit of the serine/threonine protein phosphatase 2A, which suppresses JNK phosphorylation. G5PR is upregulated in activated B cells, in Ki67-negative centrocytes at germinal centers (GCs), and in purified B220(+)Fas(+)GL7(+) mature GC B cells following Ag immunization. G5PR rescues transformed B cells from BCR-mediated activation-induced cell death by suppression of late-phase JNK activation. In G5PR-transgenic (G5PR(Tg)) mice, G5PR overexpression leads to an augmented generation of GC B cells via an increase in non-Ag-specific B cells and a consequent reduction in the proportion of Ag-specific B cells and high-affinity Ab production after immunization with nitrophenyl-conjugated chicken γ-globulin. G5PR overexpression impaired the affinity-maturation of Ag-specific B cells, presumably by diluting the numbers of high-affinity B cells. However, aged nonimmunized female G5PR(Tg) mice showed an increase in the numbers of peritoneal B-1a cells and the generation of autoantibodies. G5PR overexpression did not affect the proliferation of B-1a and B-2 cells but rescued B-1a cells from activation-induced cell death in vitro. G5PR might play a pivotal role in B cell selection not only for B-2 cells but also for B-1 cells in peripheral lymphoid organs.
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Affiliation(s)
- Masahiro Kitabatake
- Department of Immunology, Graduate School of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
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14
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Kurimchak A, Graña X. PP2A holoenzymes negatively and positively regulate cell cycle progression by dephosphorylating pocket proteins and multiple CDK substrates. Gene 2012; 499:1-7. [PMID: 22387205 DOI: 10.1016/j.gene.2012.02.015] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/04/2012] [Accepted: 02/13/2012] [Indexed: 12/11/2022]
Abstract
Cell cycle progression is negatively regulated by the retinoblastoma family of pocket proteins and CDK inhibitors (CKIs). In contrast, CDKs promote progression through multiple phases of the cell cycle. One prominent way by which CDKs promote cell cycle progression is by inactivation of pocket proteins via hyperphosphorylation. Reactivation of pocket proteins to halt cell cycle progression requires dephosphorylation of multiple CDK-phosphorylated sites and is accomplished by PP2A and PP1 serine/threonine protein phosphatases. The same phosphatases are also implicated in dephosphorylation of multiple CDK substrates as cells exit mitosis and reenter the G1 phase of the cell cycle. This review is primarily focused on the role of PP2A and PP1 in the activation of pocket proteins during the cell cycle and in response to signaling cues that trigger cell cycle exit. Other functions of PP2A during the cell cycle will be discussed in brief, as comprehensive reviews on this topic have been published recently (De Wulf et al., 2009; Wurzenberger and Gerlich, 2011).
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Affiliation(s)
- Alison Kurimchak
- Fels Institute for Cancer Research and Molecular Biology, Philadelphia, PA 19140, USA
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15
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Phosphorylation-dependent association of the G4-1/G5PR regulatory subunit with IKKβ negatively modulates NF-κB activation through recruitment of protein phosphatase 5. Biochem J 2010; 433:187-96. [DOI: 10.1042/bj20100247] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The transcription factor NF-κB (nuclear factor κB) co-ordinates various gene expressions in response to diverse signals and is a critical regulator of inflammation and innate immunity. Several negative regulators of NF-κB have been identified as downstream targets of NF-κB and function as a feedback control of NF-κB activation. A few protein phosphatases have also been shown to inactivate NF-κB activation. However, little is known about how protein phosphatases detect and respond to NF-κB activation. In the present study, we report a regulatory subunit of PP5 (protein phosphatase 5), G4-1, that physically interacts with IKKβ [IκB (inhibitor of NF-κB) kinase β] and negatively regulates NF-κB activation. The association of G4-1 with IKKβ depends on the kinase activity of IKKβ. Mapping of the G4-1-binding domain of IKKβ reveals that the serine-rich domain in the C-terminus of IKKβ is required for G4-1 binding. When seven autophosphorylated serine residues in this domain were mutated to alanine, the mutant form of IKKβ lost its ability to bind G4-1 and was more potent than the wild-type kinase to activate NF-κB. Knockdown of G4-1 enhanced TNFα (tumour necrosis factor α)-induced NF-κB activity, and knockdown of PP5 totally abolished the inhibitory activity of G4-1 on NF-κB activation. The results of the present study suggest that G4-1 functions as an adaptor to recruit PP5 to the phosphorylated C-terminus of activated IKKβ and to down-regulate the activation of IKKβ.
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16
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Escobar J, Pereda J, Arduini A, Sandoval J, Sabater L, Aparisi L, López-Rodas G, Sastre J. Protein phosphatases and chromatin modifying complexes in the inflammatory cascade in acute pancreatitis. World J Gastrointest Pharmacol Ther 2010; 1:75-80. [PMID: 21577300 PMCID: PMC3091150 DOI: 10.4292/wjgpt.v1.i3.75] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 02/10/2010] [Accepted: 02/17/2010] [Indexed: 02/05/2023] Open
Abstract
Acute pancreatitis is an inflammation of the pancreas that may lead to systemic inflammatory response syndrome and death due to multiple organ failure. Acinar cells, together with leukocytes, trigger the inflammatory cascade in response to local damage of the pancreas. Amplification of the inflammatory cascade requires up-regulation of pro-inflammatory cytokines and this process is mediated not only by nuclear factor κB but also by chromatin modifying complexes and chromatin remodeling. Among the different families of histone acetyltransferases, the p300/CBP family seems to be particularly associated with the inflammatory process. cAMP activates gene expression via the cAMP-responsive element (CRE) and the transcription factor CRE-binding protein (CREB). CREB can be phosphorylated and activated by different kinases, such as protein kinase A and MAPK, and then it recruits the histone acetyltransferase co-activator CREB-binding protein (CBP) and its homologue p300. The recruitment of CBP/p300 and changes in the level of histone acetylation are required for transcription activation. Transcriptional repression is also a dynamic and essential mechanism of down-regulation of genes for resolution of inflammation, which seems to be mediated mainly by protein phosphatases (PP1, PP2A and MKP1) and histone deacetylases (HDACs). Class II HDACs are key transcriptional regulators whose activities are controlled via phosphorylation-dependent nucleo/cytoplasmic shuttling. PP2A is responsible for dephosphorylation of class II HDACs, triggering nuclear localization and repression of target genes, whereas phosphorylation triggers cytoplasmic localization leading to activation of target genes. The potential benefit from treatment with phosphodiesterase inhibitors and histone deacetylase inhibitors is discussed.
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Affiliation(s)
- Javier Escobar
- Javier Escobar, Javier Pereda, Alessandro Arduini, Juan Sastre, Department of Physiology, University of Valencia, 46100 Burjasot (Valencia), Spain
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17
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Zwaenepoel K, Goris J, Erneux C, Parker PJ, Janssens V. Protein phosphatase 2A PR130/B''alpha1 subunit binds to the SH2 domain-containing inositol polyphosphate 5-phosphatase 2 and prevents epidermal growth factor (EGF)-induced EGF receptor degradation sustaining EGF-mediated signaling. FASEB J 2009; 24:538-47. [PMID: 19825976 DOI: 10.1096/fj.09-140228] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
To elucidate novel cell biological functions of specific protein phosphatase 2A (PP2A) holoenzymes, we identified and biochemically characterized a complex between the Src homology 2 (SH2) domain-containing inositol polyphosphate 5-phosphatase 2 (SHIP2) and a PP2A holoenzyme comprising PR130/B''alpha1 as a regulatory subunit (PP2A(T130)) in several mammalian cell lines. PR130/B''alpha1 and SHIP2 partially colocalize in untreated HeLa cells, and both translocate to the cell membrane on epidermal growth factor (EGF) stimulation. Concomitantly, a transient EGF-dependent interaction of PR130/B''alpha1 with the EGF receptor (EGFR) was observed, whereas the SHIP2-PR130 interaction remained constitutive. As previously reported for SHIP2, RNA interference-mediated knockdown of PR130 in COS-7 cells resulted in increased EGF-induced proteasome-dependent EGFR degradation, and an increased interaction of EGFR with the E3 ligase c-Cbl. In concordance with faster EGFR clearance or desensitization, intrinsic EGFR kinase activity (phospho-Tyr-1068) and downstream protein kinase B and extracellular signal-regulated kinase/mitogen-activated protein kinase pathways were more rapidly inactivated in PR130-knockdown cells. Notably, these effects could be rescued by reintroduction of RNA interference-resistant Myc-PR130, excluding any off-target effect. These data highlight a novel biological role of the PP2A(T130) holoenzyme in EGF signaling through interaction with EGFR and the phosphatidylinositol (3,4,5)-trisphosphate 5-phosphatase SHIP2. This interaction may be of clinical relevance as dysfunction of EGF-mediated signaling has been linked to various human cancers.
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Affiliation(s)
- Karen Zwaenepoel
- Protein Phosphorylation and Proteomics Laboratory, Dept. of Molecular Cell Biology, Faculty of Medicine, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
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18
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Zwaenepoel K, Louis JV, Goris J, Janssens V. Diversity in genomic organisation, developmental regulation and distribution of the murine PR72/B" subunits of protein phosphatase 2A. BMC Genomics 2008; 9:393. [PMID: 18715506 PMCID: PMC2529318 DOI: 10.1186/1471-2164-9-393] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Accepted: 08/20/2008] [Indexed: 01/03/2023] Open
Abstract
Background Protein phosphatase 2A (PP2A) is a serine/threonine-specific phosphatase displaying vital functions in growth and development through its role in various signalling pathways. PP2A holoenzymes comprise a core dimer composed of a catalytic C and a structural A subunit, which can associate with a variable B-type subunit. The importance of the B-type subunits for PP2A regulation cannot be overestimated as they determine holoenzyme localisation, activity and substrate specificity. Three B-type subunit families have been identified: PR55/B, PR61/B' and PR72/B", of which the latter is currently the least characterised. Results We deduced the sequences and genomic organisation of the different murine PR72/B" isoforms: three genes encode nine isoforms, five of which are abundantly expressed and give rise to genuine PP2A subunits. Thereby, one novel subunit was identified. Using Northern blotting, we examined the tissue-specific and developmental expression of these subunits. All subunits are highly expressed in heart, suggesting an important cardiac function. Immunohistochemical analysis revealed a striated expression pattern of PR72 and PR130 in heart and skeletal muscle, but not in bladder smooth muscle. The subcellular localisation and cell cycle regulatory ability of several PR72/B" isoforms were determined, demonstrating differences as well as similarities. Conclusion In contrast to PR55/B and PR61/B', the PR72/B" family seems evolutionary more divergent, as only two of the murine genes have a human orthologue. We have integrated these results in a more consistent nomenclature of both human and murine PR72/B" genes and their transcripts/proteins. Our results provide a platform for the future generation of PR72/B" knockout mice.
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Affiliation(s)
- Karen Zwaenepoel
- Protein Phosphorylation and Proteomics Group, Dept, Molecular Cell Biology, Faculty of Medicine, K,U, Leuven, Gasthuisberg O&N1, Herestraat 49 box 901, B-3000 Leuven, Belgium.
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19
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Eichhorn PJA, Creyghton MP, Bernards R. Protein phosphatase 2A regulatory subunits and cancer. Biochim Biophys Acta Rev Cancer 2008; 1795:1-15. [PMID: 18588945 DOI: 10.1016/j.bbcan.2008.05.005] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 05/20/2008] [Accepted: 05/21/2008] [Indexed: 01/06/2023]
Abstract
The serine/threonine protein phosphatase (PP2A) is a trimeric holoenzyme that plays an integral role in the regulation of a number of major signaling pathways whose deregulation can contribute to cancer. The specificity and activity of PP2A are highly regulated through the interaction of a family of regulatory B subunits with the substrates. Accumulating evidence indicates that PP2A acts as a tumor suppressor. In this review we summarize the known effects of specific PP2A holoenzymes and their roles in cancer relevant pathways. In particular we highlight PP2A function in the regulation of MAPK and Wnt signaling.
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Affiliation(s)
- Pieter J A Eichhorn
- Division of Molecular Carcinogenesis, Center for Cancer Genomics and Center for Biomedical Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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20
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Janssens V, Longin S, Goris J. PP2A holoenzyme assembly: in cauda venenum (the sting is in the tail). Trends Biochem Sci 2008; 33:113-21. [PMID: 18291659 DOI: 10.1016/j.tibs.2007.12.004] [Citation(s) in RCA: 307] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 12/20/2007] [Accepted: 12/21/2007] [Indexed: 01/22/2023]
Abstract
Protein phosphatase 2A (PP2A), a major phospho-serine/threonine phosphatase, is conserved throughout eukaryotes. It dephosphorylates a plethora of cellular proteins, including kinases and other signaling molecules involved in cell division, gene regulation, protein synthesis and cytoskeleton organization. PP2A enzymes typically exist as heterotrimers comprising catalytic C-, structural A- and regulatory B-type subunits. The B-type subunits function as targeting and substrate-specificity factors; hence, holoenzyme assembly with the appropriate B-type subunit is crucial for PP2A specificity and regulation. Recently, several biochemical and structural determinants have been described that affect PP2A holoenzyme assembly. Moreover, the effects of specific post-translational modifications of the C-terminal tail of the catalytic subunit indicate that a 'code' might regulate dynamic exchange of regulatory B-type subunits, thus affecting the specificity of PP2A.
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Affiliation(s)
- Veerle Janssens
- Protein Phosphorylation and Proteomics Laboratory, Department of Molecular Cell Biology, Faculty of Medicine, K.U. Leuven, Leuven, Belgium
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21
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Protein phosphatase subunit G5PR that regulates the JNK-mediated apoptosis signal is essential for the survival of CD4 and CD8 double-positive thymocytes. Mol Immunol 2008; 45:2028-37. [DOI: 10.1016/j.molimm.2007.10.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2007] [Revised: 10/11/2007] [Accepted: 10/12/2007] [Indexed: 11/22/2022]
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22
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Huq Ronny FM, Igarashi H, Sakaguchi N. BCR-crosslinking induces a transcription of protein phosphatase component G5PR that is required for mature B-cell survival. Biochem Biophys Res Commun 2006; 340:338-46. [PMID: 16343422 DOI: 10.1016/j.bbrc.2005.11.169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Accepted: 11/23/2005] [Indexed: 10/25/2022]
Abstract
BCR-crosslinking triggers activation-induced cell death (AICD) selectively in the restricted stage of B-cell differentiation. We examined the transcription of a protein phosphatase subunit G5PR in immature and mature B-cells, because absence of this factor augmented cell sensitivity to AICD, associated with increased activation of JNK and Bim. BCR-crosslinking-induced G5pr transcription in AICD-resistant mature splenic IgM(lo)IgD(hi) B-cells but not in AICD susceptible immature IgM(hi)IgD(lo) B-cells. Thus, G5pr induction correlated with the prevention of AICD; High in mature splenic CD23(hi) B-cells but low in immature B-cells of neonatal mice, sub-lethally irradiated mice, or xid mice. Lack of G5pr upregulation was associated with the prolonged activation of JNK. The G5pr cDNA transfection protected an immature B-cell line WEHI-231 from BCR-mediated AICD. The differential expression of G5PR might be responsible for the antigen-dependent selection of B-cells.
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Affiliation(s)
- Faisal Mahmudul Huq Ronny
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan
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23
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Xing Y, Igarashi H, Wang X, Sakaguchi N. Protein phosphatase subunit G5PR is needed for inhibition of B cell receptor-induced apoptosis. ACTA ACUST UNITED AC 2005; 202:707-19. [PMID: 16129705 PMCID: PMC2212881 DOI: 10.1084/jem.20050637] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
B cell receptor (BCR) cross-linking induces B cell proliferation and sustains survival through the phosphorylation-dependent signals. We report that a loss of the protein phosphatase component G5PR increased the activation-induced cell death (AICD) and thus impaired B cell survival. G5PR associates with GANP, whose expression is up-regulated in mature B cells of the peripheral lymphoid organs. To study G5PR function, the G5pr gene was conditionally targeted with the CD19-Cre combination (G5pr−/− mice). The G5pr−/− mice had a decreased number of splenic B cells (60% of the controls). G5pr−/− B cells showed a normal proliferative response to lipopolysaccharide or anti-CD40 antibody stimulation but not to BCR cross-linking with or without IL-4 in vitro. G5pr−/− B cells did not show abnormalities in the BCR-mediated activation of Erks and NF-κB, cyclin D2 induction, or Akt activation. However, G5pr−/− B cells were sensitive to AICD caused by BCR cross-linking. This was associated with an increased depolarization of the mitochondrial membrane and the enhanced activation of c-Jun NH2-terminal protein kinase and Bim. These results suggest that G5PR is required for the BCR-mediated proliferation associated with the prevention of AICD in mature B cells.
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Affiliation(s)
- Yan Xing
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Japan
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24
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Sakaguchi N, Kimura T, Matsushita S, Fujimura S, Shibata J, Araki M, Sakamoto T, Minoda C, Kuwahara K. Generation of high-affinity antibody against T cell-dependent antigen in the Ganp gene-transgenic mouse. THE JOURNAL OF IMMUNOLOGY 2005; 174:4485-94. [PMID: 15814669 DOI: 10.4049/jimmunol.174.8.4485] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Generation of high-affinity Ab is impaired in mice lacking germinal center-associated DNA primase (GANP) in B cells. In this study, we examined the effect of its overexpression in ganp transgenic C57BL/6 mice (Ganp(Tg)). Ganp(Tg) displayed normal phenotype in B cell development, serum Ig levels, and responses against T cell-independent Ag; however, it generated the Ab with much higher affinity against nitrophenyl-chicken gammaglobulin in comparison with C57BL/6. To further examine the affinity increase, we established hybridomas producing high-affinity mAbs and compared their affinities using BIAcore. C57BL/6 generated high-affinity anti-nitrophenyl mAbs (K(D) approximately 2.50 x 10(-7) M) of IgG1/lambda1 and contained the V(H)186.2 region with W33L mutation. Ganp(Tg) generated much higher affinity (K(D) > 1.57 x 10(-9) M) by usage of V(H)186.2 as well as noncanonical V(H)7183 regions. Ganp(Tg) also generated exceptionally high-affinity anti-HIV-1 (V3 peptide) mAbs (K(D) > 9.90 x 10(-11) M) with neutralizing activity. These results demonstrated that GANP is involved in V region alteration generating high-affinity Ab.
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Affiliation(s)
- Nobuo Sakaguchi
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Kumamoto, Japan.
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25
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Kutuzov MA, Andreeva AV, Voyno-Yasenetskaya TA. Regulation of apoptosis signal-regulating kinase 1 (ASK1) by polyamine levels via protein phosphatase 5. J Biol Chem 2005; 280:25388-95. [PMID: 15890660 PMCID: PMC1314983 DOI: 10.1074/jbc.m413202200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent evidence has implicated the protein phosphatase PP5 in a variety of signaling pathways. Whereas several proteins have been identified that interact with PP5 and regulate its activity, a possibility of its regulation by second messengers remains speculative. Activation of PP5 in vitro by polyunsaturated fatty acids (e.g. arachidonic acid) and fatty acyl-CoA esters (e.g. arachidonoyl-CoA) has been reported. We report here that PP5 is strongly inhibited by micromolar concentrations of a natural polyamine spermine. This inhibition was observed both in assays with a low molecular weight substrate p-nitrophenyl phosphate as well as phosphocasein and apoptosis signal-regulating kinase 1 (ASK1), thought to be a physiological substrate of PP5. Furthermore, a decrease in polyamine levels in COS-7 cells induced by alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase, led to accelerated dephosphorylation of oxidative stress-activated ASK1. This effect was suppressed by okadaic acid and by siRNA-mediated PP5 depletion, indicating that the effect of polyamine levels on ASK1 dephosphorylation was mediated by PP5. In line with the decreased ASK1 activation, polyamine depletion in COS-7 cells abrogated oxidative stress-induced activation of caspase-3, which executes ASK1-induced apoptosis, as well as caspase-3 activation induced by ASK1 overexpression, but had no effect on basal caspase-3 activity. These results implicate polyamines, emerging intracellular signaling molecules, as potential physiological regulators of PP5. Our findings also suggest a novel mechanism of the anti-apoptotic action of a decrease in polyamine levels via de-inhibition of PP5 and accelerated dephosphorylation and deactivation of ASK1.
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Affiliation(s)
| | | | - Tatyana A. Voyno-Yasenetskaya
- Address correspondence to: Tatyana Voyno-Yasenetskaya, University of Illinois, Department of Pharmacology (MC 868), 835 S. Wolcott Ave, Chicago, IL 60612, Phone: (312) 996-9823; Fax: (312) 996-1225; E-mail:
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Begley GS, Horvath AR, Taylor JC, Higgins CF. Cytoplasmic domains of the transporter associated with antigen processing and P-glycoprotein interact with subunits of the proteasome. Mol Immunol 2005; 345:124-31. [PMID: 15488952 DOI: 10.1016/j.canlet.2013.12.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 11/27/2013] [Accepted: 12/01/2013] [Indexed: 02/06/2023]
Abstract
The proteasome is a multi-protein complex that degrades cellular proteins as well as foreign proteins destined for antigen presentation. The latter function involves the immunoproteasome, in which several proteasome subunits are exchanged for gamma-interferon-induced subunits. The transporter associated with antigen processing (TAP) transports proteasome-generated peptides across the membrane of the endoplasmic reticulum (ER) prior to presentation on the plasma membrane. We demonstrate interactions between the cytoplasmic domains of TAP subunits and subunits of both the proteasome and the immunoproteasome, suggesting direct targeting of antigenic peptides to the ER via a TAP-proteasome association. We also show interaction between one of the cytoplasmic domains of P-glycoprotein and a proteasome subunit, but not the corresponding immunoproteasome subunit, suggesting a possible role for P-glycoprotein in the transport of proteasome-derived peptides.
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Affiliation(s)
- Gail S Begley
- Biology Department, Northeastern University, 330 Huntington Avenue, Boston, MA 02115, USA.
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27
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Huang S, Shu L, Easton J, Harwood FC, Germain GS, Ichijo H, Houghton PJ. Inhibition of Mammalian Target of Rapamycin Activates Apoptosis Signal-regulating Kinase 1 Signaling by Suppressing Protein Phosphatase 5 Activity. J Biol Chem 2004; 279:36490-6. [PMID: 15218033 DOI: 10.1074/jbc.m401208200] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Under serum-free conditions, rapamycin, an inhibitor of mammalian target of rapamycin (mTOR), induces a cellular stress response characterized by rapid and sustained activation of the apoptosis signal-regulating kinase 1 (ASK1) signaling pathway and selective apoptosis of cells lacking functional p53. Here we have investigated how mTOR regulates ASK1 signaling using p53-mutant rhabdomyosarcoma cells. In Rh30 cells, ASK1 was found to physically interact with protein phosphatase 5 (PP5), previously identified as a negative regulator of ASK1. Rapamycin did not affect either protein level of PP5 or association of PP5 with ASK1. Instead, rapamycin caused rapid dissociation of the PP2A-B" regulatory subunit (PR72) from the PP5-ASK1 complex, which was associated with reduced phosphatase activity of PP5. This effect was dependent on expression of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). Down-regulation of PP5 activity by rapamycin coordinately activated ASK1, leading to elevated phosphorylation of c-Jun. Amino acid deprivation, which like rapamycin inhibits mTOR signaling, also inhibited PP5 activity, caused rapid dissociation of PR72, and activated ASK1 signaling. Overexpression of PP5, but not the PP2A catalytic subunit, blocked rapamycin-induced phosphorylation of c-Jun, and protected cells from rapamycin-induced apoptosis. The results suggest that PP5 is downstream of mTOR, and positively regulated by the mTOR pathway. The findings suggest that in the absence of serum factors, mTOR signaling suppresses apoptosis through positive regulation of PP5 activity and suppression of cellular stress.
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Affiliation(s)
- Shile Huang
- Department of Molecular Pharmacology, St. Jude Children's Research Hospital, 332 Lauderdale, Memphis, TN 38105-2794, USA
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28
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Mirnics ZK, Caudell E, Gao Y, Kuwahara K, Sakaguchi N, Kurosaki T, Burnside J, Mirnics K, Corey SJ. Microarray analysis of Lyn-deficient B cells reveals germinal center-associated nuclear protein and other genes associated with the lymphoid germinal center. THE JOURNAL OF IMMUNOLOGY 2004; 172:4133-41. [PMID: 15034025 DOI: 10.4049/jimmunol.172.7.4133] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Lyn is the only member of the Src family expressed in DT40 B cells, which provide a unique model to study the singular contribution of this protein tyrosine kinase (PTK) family to cell signaling. In these cells, gene ablation of Lyn leads to defective B cell receptor signaling. Complementary DNA array analysis of Lyn-deficient DT40 cells shows that the absence of Lyn leads to down-regulation of numerous genes encoding proteins involved in B cell receptor signaling, proliferation, control of transcription, immunity/inflammation response, and cytoskeletal organization. Most of these expression changes have not been previously associated with Lyn PTK signaling. They include alterations in mRNA levels of germinal center-associated nuclear protein (germinal center-associated DNA primase) (GANP), CD74, CD22, NF-kappaB, elongation factor 1alpha, CD79b, octamer binding factor 1, Ig H chain, stathmin, and gamma-actin. Changes in GANP expression were also confirmed in Lyn-deficient mice, suggesting that Lyn PTK has a unique function not compensated for by other Src kinases. Because Lyn-deficient mice have impaired development of germinal centers in spleen, the decreased expression of GANP in the Lyn-deficient DT40 cell line and Lyn-deficient mice suggests that Lyn controls the formation and proliferation of germinal centers via GANP. GANP promoter activity was higher in wild-type vs Lyn-deficient cells. Mutation of the PU.1 binding site reduced activity in wild-type cells and had no effect in Lyn-deficient cells. The presence of Lyn enhanced PU.1 expression in a Northern blot. Thus, the following new signaling pathway has been described: Lyn-->PU.1-->GANP.
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Affiliation(s)
- Zeljka Korade Mirnics
- Department of Pediatrics, University of Pittsburgh, School of Medicine, Children's Hospital of Pittsburgh, Pittsburgh, PA 15213, USA
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Janssens V, Jordens J, Stevens I, Van Hoof C, Martens E, De Smedt H, Engelborghs Y, Waelkens E, Goris J. Identification and functional analysis of two Ca2+-binding EF-hand motifs in the B"/PR72 subunit of protein phosphatase 2A. J Biol Chem 2003; 278:10697-706. [PMID: 12524438 DOI: 10.1074/jbc.m211717200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Protein phosphatase 2A (PP2A) is a multifunctional serine/threonine phosphatase that is critical to many cellular processes including cell cycle regulation and signal transduction. PP2A is a heterotrimer containing a structural (A) and catalytic (C) subunit, associated with one variable regulatory or targeting B-type subunit, of which three families have been described to date (B/PR55, B'/PR61, and B"/PR72). We identified two functional and highly conserved Ca(2+)-binding EF-hand motifs in human B"/PR72 (denoted EF1 and EF2), demonstrating for the first time the ability of Ca(2+) to interact directly with and regulate PP2A. EF1 and EF2 apparently bind Ca(2+) with different affinities. Ca(2+) induces a significant conformational change, which is dependent on the integrity of the motifs. We have further evaluated the effects of Ca(2+) on subunit composition, subcellular targeting, catalytic activity, and function during the cell cycle of a PR72-containing PP2A trimer (PP2A(T72)) by site-directed mutagenesis of either or both motifs. The results suggest that integrity of EF2 is required for A/PR65 subunit interaction and proper nuclear targeting of PR72, whereas EF1 might mediate the effects of Ca(2+) on PP2A(T72) activity in vitro and is at least partially required for the ability of PR72 to alter cell cycle progression upon forced expression.
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Affiliation(s)
- Veerle Janssens
- Division of Biochemistry, Faculty of Medicine, Katholieke Universiteit Leuven, Herestraat 49, Belgium
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