1
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Jing S, Yi X. Exome sequencing reveals PPEF2 variant associated with high myopia. Gene 2024; 897:148091. [PMID: 38110044 DOI: 10.1016/j.gene.2023.148091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 12/08/2023] [Accepted: 12/14/2023] [Indexed: 12/20/2023]
Abstract
High myopia (HM) is a serious blinding eye disease, and genetic factors play an important role in the development of HM. In this study, whole exome sequencing (WES) was used to identify a novel variant c.A875G of the PPEF2 for a large Uyghur family with nonsyndromic HM. The variant was verified to cosegregate with HM in the family using Sanger sequencing. Another novel variant c.1959C > G in PPEF2 was identified in one of 100 sporadic cases of HM by multiplex PCR targeted amplicon sequencing (MTA-seq). The Ppef2 was verified that mainly expressed in the retinal pigment epithelium (RPE), choroid and retina tissues. Immunofluorescence (IF) and immunohistochemistry (IHC) assays showed that the PPEF2 was strongly expressed in the inner segment layer formed by photoreceptor protrusions, as well as in the outer nuclear layer. Compared with the wild-type, the c.A875G resulted in reduced protein levels but had no effect on protein subcellular localization in cells. In addition, the c.A875G variant resulted in a decreased migratory and proliferative capacity but promoted apoptosis in cells. In summary, PPEF2 was identified as a novel HM-causing gene, and this variant in PPEF2 might cause HM by regulating the migration, proliferation and apoptosis of myopia-related cells.
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Affiliation(s)
- Sili Jing
- Shaanxi Eye Hospital, Xi'an People's Hospital (Xi'an Fourth Hospital), Affiliated People's Hospital of Northwest University, Xian, 710004, China; Ophthalmology, Xinjiang Medical University Affiliated First Hospital, Urumqi, Xinjiang, China
| | - Xianglong Yi
- Ophthalmology, Xinjiang Medical University Affiliated First Hospital, Urumqi, Xinjiang, China.
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2
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Saini LK, Bheri M, Pandey GK. Protein phosphatases and their targets: Comprehending the interactions in plant signaling pathways. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 134:307-370. [PMID: 36858740 DOI: 10.1016/bs.apcsb.2022.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Protein phosphorylation is a vital reversible post-translational modification. This process is established by two classes of enzymes: protein kinases and protein phosphatases. Protein kinases phosphorylate proteins while protein phosphatases dephosphorylate phosphorylated proteins, thus, functioning as 'critical regulators' in signaling pathways. The eukaryotic protein phosphatases are classified as phosphoprotein phosphatases (PPP), metallo-dependent protein phosphatases (PPM), protein tyrosine (Tyr) phosphatases (PTP), and aspartate (Asp)-dependent phosphatases. The PPP and PPM families are serine (Ser)/threonine (Thr) specific phosphatases (STPs) that dephosphorylate Ser and Thr residues. The PTP family dephosphorylates Tyr residues while dual-specificity phosphatases (DsPTPs/DSPs) dephosphorylate Ser, Thr, and Tyr residues. The composition of these enzymes as well as their substrate specificity are important determinants of their functional significance in a number of cellular processes and stress responses. Their role in animal systems is well-understood and characterized. The functional characterization of protein phosphatases has been extensively covered in plants, although the comprehension of their mechanistic basis is an ongoing pursuit. The nature of their interactions with other key players in the signaling process is vital to our understanding. The substrates or targets determine their potential as well as magnitude of the impact they have on signaling pathways. In this article, we exclusively overview the various substrates of protein phosphatases in plant signaling pathways, which are a critical determinant of the outcome of various developmental and stress stimuli.
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Affiliation(s)
- Lokesh K Saini
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India
| | - Malathi Bheri
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India
| | - Girdhar K Pandey
- Department of Plant Molecular Biology, University of Delhi South Campus, Dhaula Kuan, New Delhi, India.
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3
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Smylla TK, Wagner K, Huber A. The Role of Reversible Phosphorylation of Drosophila Rhodopsin. Int J Mol Sci 2022; 23:ijms232314674. [PMID: 36499010 PMCID: PMC9740569 DOI: 10.3390/ijms232314674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/18/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022] Open
Abstract
Vertebrate and fly rhodopsins are prototypical GPCRs that have served for a long time as model systems for understanding GPCR signaling. Although all rhodopsins seem to become phosphorylated at their C-terminal region following activation by light, the role of this phosphorylation is not uniform. Two major functions of rhodopsin phosphorylation have been described: (1) inactivation of the activated rhodopsin either directly or by facilitating binding of arrestins in order to shut down the visual signaling cascade and thus eventually enabling a high-temporal resolution of the visual system. (2) Facilitating endocytosis of activated receptors via arrestin binding that in turn recruits clathrin to the membrane for clathrin-mediated endocytosis. In vertebrate rhodopsins the shutdown of the signaling cascade may be the main function of rhodopsin phosphorylation, as phosphorylation alone already quenches transducin activation and, in addition, strongly enhances arrestin binding. In the Drosophila visual system rhodopsin phosphorylation is not needed for receptor inactivation. Its role here may rather lie in the recruitment of arrestin 1 and subsequent endocytosis of the activated receptor. In this review, we summarize investigations of fly rhodopsin phosphorylation spanning four decades and contextualize them with regard to the most recent insights from vertebrate phosphorylation barcode theory.
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Liang QL, Nie LB, Li TT, Elsheikha HM, Sun LX, Zhang ZW, Zhao DY, Zhu XQ, Wang JL. Functional Characterization of 17 Protein Serine/Threonine Phosphatases in Toxoplasma gondii Using CRISPR-Cas9 System. Front Cell Dev Biol 2022; 9:738794. [PMID: 35083211 PMCID: PMC8785970 DOI: 10.3389/fcell.2021.738794] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 11/24/2021] [Indexed: 11/13/2022] Open
Abstract
Protein serine/threonine phosphatases (PSPs), found in various plants and protozoa, are involved in the regulation of various biological processes. However, very little is known about the role of PSPs in the pathogenicity of the apicomplexan protozoan Toxoplasma gondii. Herein, the subcellular localization of 17 PSPs (PP5, PP7, EFPP, SLP, PPM3F, PPM4, PPM5A, PPM5B, PPM6, PPM8, PPM9, PPM12, PPM14, PPM18, CTD1, CTD2, and CTD3) was examined by 6× HA tagging of endogenous genes in C-terminal. The PSPs were detected in the cytoplasm (PP5, EFPP, PPM8, and CTD2), dense granules (SLP), nucleus (PPM4 and PPM9), inner membrane complex (PPM12), basal complex (CTD3), and apical pole (PP7). The remaining PSPs exhibited low or undetectable level of expression. To characterize the contribution of these genes to the infectivity of T. gondii, knock-out (KO) strains of type I RH strain deficient in the 17 psp genes and KO type II Pru strain deficient in pp7 and slp genes were constructed. The pathogenicity of individual RHΔpsp mutants was characterized in vitro using plaque, egress, and intracellular replication assays, and mouse infection, while pathogenicity of PruΔpp7 and PruΔslp mutant strains was evaluated by examining the parasite lytic cycle in vitro and assessment of brain cyst burden in mice. No significant differences were observed between 16 RHΔpsp strains and wild-type (WT) RH strain. However, RHΔpp7 exhibited significantly lower invasion efficiency and parasitophorous vacuole formation in vitro, and less virulence in mice compared with other RHΔpsp and WT strains. In addition, PruΔpp7 exhibited marked attenuation of virulence and significant reduction in the brain cyst burden in mice compared with PruΔslp and WT strains, suggesting the key role of PP7 in the virulence of T. gondii. Comparative transcriptomic profiling of the 17 psp genes showed that they may play different roles in the pathogenesis of different genotypes or life cycle stages of T. gondii. These findings provide new insight into the role of PSPs in the pathogenesis of T. gondii.
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Affiliation(s)
- Qin-Li Liang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Lan-Bi Nie
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Ting-Ting Li
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Hany M. Elsheikha
- Faculty of Medicine and Health Sciences, School of Veterinary Medicine and Science, University of Nottingham, Loughborough, United Kingdom
| | - Li-Xiu Sun
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Zhi-Wei Zhang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Dan-Yu Zhao
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Xing-Quan Zhu
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
- College of Veterinary Medicine, Shanxi Agricultural University, Taigu, China
- Key Laboratory of Veterinary Public Health of Higher Education of Yunnan Province, College of Veterinary Medicine, Yunnan Agricultural University, Kunming, China
| | - Jin-Lei Wang
- State Key Laboratory of Veterinary Etiological Biology, Key Laboratory of Veterinary Parasitology of Gansu Province, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
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5
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Kerk D, Mattice JF, Valdés-Tresanco ME, Noskov SY, Ng KKS, Moorhead GB. The origin and radiation of the phosphoprotein phosphatase (PPP) enzymes of Eukaryotes. Sci Rep 2021; 11:13681. [PMID: 34211082 PMCID: PMC8249667 DOI: 10.1038/s41598-021-93206-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 06/22/2021] [Indexed: 11/18/2022] Open
Abstract
Phosphoprotein phosphatase (PPP) enzymes are ubiquitous proteins involved in cellular signaling pathways and other functions. Here we have traced the origin of the PPP sequences of Eukaryotes and their radiation. Using a bacterial PPP Hidden Markov Model (HMM) we uncovered "BacterialPPP-Like" sequences in Archaea. A HMM derived from eukaryotic PPP enzymes revealed additional, unique sequences in Archaea and Bacteria that were more like the eukaryotic PPP enzymes then the bacterial PPPs. These sequences formed the basis of phylogenetic tree inference and sequence structural analysis allowing the history of these sequence types to be elucidated. Our phylogenetic tree data strongly suggest that eukaryotic PPPs ultimately arose from ancestors in the Asgard archaea. We have clarified the radiation of PPPs within Eukaryotes, substantially expanding the range of known organisms with PPP subtypes (Bsu1, PP7, PPEF/RdgC) previously thought to have a more restricted distribution. Surprisingly, sequences from the Methanosarcinaceae (Euryarchaeota) form a strongly supported sister group to eukaryotic PPPs in our phylogenetic analysis. This strongly suggests an intimate association between an Asgard ancestor and that of the Methanosarcinaceae. This is highly reminiscent of the syntrophic association recently demonstrated between the cultured Lokiarchaeal species Prometheoarchaeum and a methanogenic bacterial species.
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Affiliation(s)
- David Kerk
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada
| | - Jordan F Mattice
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada
| | - Mario E Valdés-Tresanco
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada
| | - Sergei Yu Noskov
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada
| | - Kenneth K-S Ng
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada
| | - Greg B Moorhead
- Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada.
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6
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Zhang Q, Fan Z, Zhang L, You Q, Wang L. Strategies for Targeting Serine/Threonine Protein Phosphatases with Small Molecules in Cancer. J Med Chem 2021; 64:8916-8938. [PMID: 34156850 DOI: 10.1021/acs.jmedchem.1c00631] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Among numerous posttranslational regulation patterns, phosphorylation is reversibly controlled by the balance of kinases and phosphatases. The major form of cellular signaling involves the reversible phosphorylation of proteins on tyrosine, serine, or threonine residues. However, altered phosphorylation levels are found in diverse diseases, including cancer, making kinases and phosphatases ideal drug targets. In contrast to the success of prosperous kinase inhibitors, design of small molecules targeting phosphatase is struggling due to past bias and difficulty. This is especially true for serine/threonine phosphatases, one of the largest phosphatase families. From this perspective, we aim to provide insights into serine/threonine phosphatases and the small molecules targeting these proteins for drug development, especially in cancer. Through highlighting the modulation strategies, we aim to provide basic principles for the design of small molecules and future perspectives for the application of drugs targeting serine/threonine phosphatases.
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Affiliation(s)
- Qiuyue Zhang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Zhongjiao Fan
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Lianshan Zhang
- Shanghai Hengrui Pharmaceutical Co., Ltd., Shanghai 200245, China
| | - Qidong You
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Lei Wang
- State Key Laboratory of Natural Medicines and Jiangsu Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing 210009, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
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7
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Lavoie-Ouellet C, Clark MÈ, Ruiz J, Saindon AA, Leclerc P. The protein phosphatase with EF-hand domain 1 is a calmodulin-binding protein that interacts with proteins involved in sperm capacitation, binding to the zona pellucida, and motility. Mol Reprod Dev 2021; 88:302-317. [PMID: 33783058 DOI: 10.1002/mrd.23467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 11/12/2022]
Abstract
Spermatozoa are highly specialized cells whose fertilizing and motility functions highly depend on intracellular Ca2+ -mediated events and protein posttranslational modifications like phosphorylation. Our group previously identified PPEF1, the Ser/Thr phosphatase with EF-hand domain 1, among calmodulin-affinity pulled down sperm proteins. As the mammalian ortholog of the Drosophila phosphatase rdgC that dephosphorylates rhodopsin, PPEF1 has been studied mostly in the retina. The presence and importance of this Ca2+ /calmodulin-binding protein phosphatase has not been studied in sperm or testicular functions despite its high expression level. In this study, we show that PPEF1 is present in testicular germ cells, and in mouse, human and bull spermatozoa where it is localized predominantly in the neck and acrosome areas. Different transcript variants encoding four predicted isoforms were detected by reverse transcription polymerase chain reaction in bull testis, spermatocytes and spermatids. Phosphatase activity of immunoprecipitated sperm PPEF1 was detected using the substrate pNPP and analysis of the coimmunoprecipitated proteins reveal an enrichment in the biological processes of sperm capacitation, binding to the zona pellucida and motility. Although this is the first demonstration of the presence of PPEF1 in sperm and testicular germ cells, its involvement in sperm fertilizing ability and motility, and the mechanisms regulating its activity remain to be further investigated.
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Affiliation(s)
- Camille Lavoie-Ouellet
- Département d'Obstétrique, gynécologie et reproduction, Centre de recherche en reproduction, développement et santé intergénérationnelle, Université Laval, Axe reproduction, santé de la mère et de l'enfant, Centre de recherche du CHU de Québec-Université Laval, Quebec City, Québec, Canada
| | - Marie-Ève Clark
- Département d'Obstétrique, gynécologie et reproduction, Centre de recherche en reproduction, développement et santé intergénérationnelle, Université Laval, Axe reproduction, santé de la mère et de l'enfant, Centre de recherche du CHU de Québec-Université Laval, Quebec City, Québec, Canada
| | - Juliana Ruiz
- Département d'Obstétrique, gynécologie et reproduction, Centre de recherche en reproduction, développement et santé intergénérationnelle, Université Laval, Axe reproduction, santé de la mère et de l'enfant, Centre de recherche du CHU de Québec-Université Laval, Quebec City, Québec, Canada
| | - Andrée-Anne Saindon
- Département d'Obstétrique, gynécologie et reproduction, Centre de recherche en reproduction, développement et santé intergénérationnelle, Université Laval, Axe reproduction, santé de la mère et de l'enfant, Centre de recherche du CHU de Québec-Université Laval, Quebec City, Québec, Canada
| | - Pierre Leclerc
- Département d'Obstétrique, gynécologie et reproduction, Centre de recherche en reproduction, développement et santé intergénérationnelle, Université Laval, Axe reproduction, santé de la mère et de l'enfant, Centre de recherche du CHU de Québec-Université Laval, Quebec City, Québec, Canada
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8
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Bheri M, Mahiwal S, Sanyal SK, Pandey GK. Plant protein phosphatases: What do we know about their mechanism of action? FEBS J 2020; 288:756-785. [PMID: 32542989 DOI: 10.1111/febs.15454] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 05/27/2020] [Accepted: 06/09/2020] [Indexed: 12/30/2022]
Abstract
Protein phosphorylation is a major reversible post-translational modification. Protein phosphatases function as 'critical regulators' in signaling networks through dephosphorylation of proteins, which have been phosphorylated by protein kinases. A large understanding of their working has been sourced from animal systems rather than the plant or the prokaryotic systems. The eukaryotic protein phosphatases include phosphoprotein phosphatases (PPP), metallo-dependent protein phosphatases (PPM), protein tyrosine (Tyr) phosphatases (PTP), and aspartate (Asp)-dependent phosphatases. The PPP and PPM families are serine(Ser)/threonine(Thr)-specific phosphatases (STPs), while PTP family is Tyr specific. Dual-specificity phosphatases (DsPTPs/DSPs) dephosphorylate Ser, Thr, and Tyr residues. PTPs lack sequence homology with STPs, indicating a difference in catalytic mechanisms, while the PPP and PPM families share a similar structural fold indicating a common catalytic mechanism. The catalytic cysteine (Cys) residue in the conserved HCX5 R active site motif of the PTPs acts as a nucleophile during hydrolysis. The PPP members require metal ions, which coordinate the phosphate group of the substrate, followed by a nucleophilic attack by a water molecule and hydrolysis. The variable holoenzyme assembly of protein phosphatase(s) and the overlap with other post-translational modifications like acetylation and ubiquitination add to their complexity. Though their functional characterization is extensively reported in plants, the mechanistic nature of their action is still being explored by researchers. In this review, we exclusively overview the plant protein phosphatases with an emphasis on their mechanistic action as well as structural characteristics.
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Affiliation(s)
- Malathi Bheri
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
| | - Swati Mahiwal
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
| | - Sibaji K Sanyal
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
| | - Girdhar K Pandey
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, India
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9
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Brautigan DL, Shenolikar S. Protein Serine/Threonine Phosphatases: Keys to Unlocking Regulators and Substrates. Annu Rev Biochem 2019; 87:921-964. [PMID: 29925267 DOI: 10.1146/annurev-biochem-062917-012332] [Citation(s) in RCA: 110] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protein serine/threonine phosphatases (PPPs) are ancient enzymes, with distinct types conserved across eukaryotic evolution. PPPs are segregated into types primarily on the basis of the unique interactions of PPP catalytic subunits with regulatory proteins. The resulting holoenzymes dock substrates distal to the active site to enhance specificity. This review focuses on the subunit and substrate interactions for PPP that depend on short linear motifs. Insights about these motifs from structures of holoenzymes open new opportunities for computational biology approaches to elucidate PPP networks. There is an expanding knowledge base of posttranslational modifications of PPP catalytic and regulatory subunits, as well as of their substrates, including phosphorylation, acetylation, and ubiquitination. Cross talk between these posttranslational modifications creates PPP-based signaling. Knowledge of PPP complexes, signaling clusters, as well as how PPPs communicate with each other in response to cellular signals should unlock the doors to PPP networks and signaling "clouds" that orchestrate and coordinate different aspects of cell physiology.
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Affiliation(s)
- David L Brautigan
- Center for Cell Signaling and Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA;
| | - Shirish Shenolikar
- Signature Research Programs in Cardiovascular and Metabolic Disorders and Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore 169857
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10
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Zwick M, Ulas T, Cho YL, Ried C, Grosse L, Simon C, Bernhard C, Busch DH, Schultze JL, Buchholz VR, Stutte S, Brocker T. Expression of the Phosphatase Ppef2 Controls Survival and Function of CD8 + Dendritic Cells. Front Immunol 2019; 10:222. [PMID: 30809231 PMCID: PMC6379467 DOI: 10.3389/fimmu.2019.00222] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 01/25/2019] [Indexed: 11/25/2022] Open
Abstract
Apoptotic cell death of Dendritic cells (DCs) is critical for immune homeostasis. Although intrinsic mechanisms controlling DC death have not been fully characterized up to now, experimentally enforced inhibition of DC-death causes various autoimmune diseases in model systems. We have generated mice deficient for Protein Phosphatase with EF-Hands 2 (Ppef2), which is selectively expressed in CD8+ DCs, but not in other related DC subtypes such as tissue CD103+ DCs. Ppef2 is down-regulated rapidly upon maturation of DCs by toll-like receptor stimuli, but not upon triggering of CD40. Ppef2-deficient CD8+ DCs accumulate the pro-apoptotic Bcl-2-like protein 11 (Bim) and show increased apoptosis and reduced competitve repopulation capacities. Furthermore, Ppef2−/− CD8+ DCs have strongly diminished antigen presentation capacities in vivo, as CD8+ T cells primed by Ppef2−/− CD8+ DCs undergo reduced expansion. In conclusion, our data suggests that Ppef2 is crucial to support survival of immature CD8+ DCs, while Ppef2 down-regulation during DC-maturation limits T cell responses.
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Affiliation(s)
- Markus Zwick
- Faculty of Medicine, Biomedical Center (BMC), Institute for Immunology, LMU Munich, Planegg-Martinsried, Germany
| | - Thomas Ulas
- Life and Medical Sciences Institute, Bonn, Germany
| | - Yi-Li Cho
- Institute for Medical Microbiology, Immunology and Hygiene, Technische Universität München, Munich, Germany
| | - Christine Ried
- Faculty of Medicine, Biomedical Center (BMC), Institute for Immunology, LMU Munich, Planegg-Martinsried, Germany
| | - Leonie Grosse
- Faculty of Medicine, Biomedical Center (BMC), Institute for Immunology, LMU Munich, Planegg-Martinsried, Germany
| | - Charlotte Simon
- Faculty of Medicine, Biomedical Center (BMC), Institute for Immunology, LMU Munich, Planegg-Martinsried, Germany
| | - Caroline Bernhard
- Faculty of Medicine, Biomedical Center (BMC), Institute for Immunology, LMU Munich, Planegg-Martinsried, Germany
| | - Dirk H Busch
- Institute for Medical Microbiology, Immunology and Hygiene, Technische Universität München, Munich, Germany
| | - Joachim L Schultze
- Life and Medical Sciences Institute, Bonn, Germany.,PRECISE-Platform for Single Cell Genomics and Epigenomics at the German Center for Neurodegenerative Diseases (DZNE) and the University of Bonn, Bonn, Germany
| | - Veit R Buchholz
- Institute for Medical Microbiology, Immunology and Hygiene, Technische Universität München, Munich, Germany
| | - Susanne Stutte
- Faculty of Medicine, Biomedical Center (BMC), Institute for Immunology, LMU Munich, Planegg-Martinsried, Germany
| | - Thomas Brocker
- Faculty of Medicine, Biomedical Center (BMC), Institute for Immunology, LMU Munich, Planegg-Martinsried, Germany
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11
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Swingle MR, Honkanen RE. Inhibitors of Serine/Threonine Protein Phosphatases: Biochemical and Structural Studies Provide Insight for Further Development. Curr Med Chem 2019; 26:2634-2660. [PMID: 29737249 PMCID: PMC10013172 DOI: 10.2174/0929867325666180508095242] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 02/05/2018] [Accepted: 03/29/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND The reversible phosphorylation of proteins regulates many key functions in eukaryotic cells. Phosphorylation is catalyzed by protein kinases, with the majority of phosphorylation occurring on side chains of serine and threonine residues. The phosphomonoesters generated by protein kinases are hydrolyzed by protein phosphatases. In the absence of a phosphatase, the half-time for the hydrolysis of alkyl phosphate dianions at 25º C is over 1 trillion years; knon ~2 x 10-20 sec-1. Therefore, ser/thr phosphatases are critical for processes controlled by reversible phosphorylation. METHODS This review is based on the literature searched in available databases. We compare the catalytic mechanism of PPP-family phosphatases (PPPases) and the interactions of inhibitors that target these enzymes. RESULTS PPPases are metal-dependent hydrolases that enhance the rate of hydrolysis ([kcat/kM]/knon ) by a factor of ~1021, placing them among the most powerful known catalysts on earth. Biochemical and structural studies indicate that the remarkable catalytic proficiencies of PPPases are achieved by 10 conserved amino acids, DXH(X)~26DXXDR(X)~20- 26NH(X)~50H(X)~25-45R(X)~30-40H. Six act as metal-coordinating residues. Four position and orient the substrate phosphate. Together, two metal ions and the 10 catalytic residues position the phosphoryl group and an activated bridging water/hydroxide nucleophile for an inline attack upon the substrate phosphorous atom. The PPPases are conserved among species, and many structurally diverse natural toxins co-evolved to target these enzymes. CONCLUSION Although the catalytic site is conserved, opportunities for the development of selective inhibitors of this important group of metalloenzymes exist.
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Affiliation(s)
- Mark R Swingle
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile AL 36688, United States
| | - Richard E Honkanen
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile AL 36688, United States
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12
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Strauch L, Pfannstiel J, Huber A, Voolstra O. Solubility and subcellular localization of the three Drosophila RDGC phosphatase variants are determined by acylation. FEBS Lett 2018; 592:2403-2413. [PMID: 29920663 DOI: 10.1002/1873-3468.13163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 06/06/2018] [Accepted: 06/11/2018] [Indexed: 01/26/2023]
Abstract
Protein phosphorylation is an abundant molecular switch that regulates a multitude of cellular processes. In contrast to other subfamilies of phosphoprotein phosphatases, the PPEF subfamily is only poorly investigated. Drosophila retinal degeneration C (RDGC) constitutes the founding member of the PPEF subfamily. RDGC dephosphorylates the visual pigment rhodopsin and the ion channel TRP.However, rdgC null mutant flies exhibit rhodopsin and TRP hyperphosphorylation, altered photoreceptor physiology, and retinal degeneration. Here, we report the identification of a third RDGC protein variant and show that the three RDGC isoforms harbor different N-termini that determine solubility and subcellular targeting due to fatty acylation. Taken together, solubility and subcellular targeting of RDGC splice variants are determined by their N-termini.
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Affiliation(s)
- Lisa Strauch
- Department of Biosensorics, Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Jens Pfannstiel
- Core Facility, Mass Spectrometry Unit, University of Hohenheim, Stuttgart, Germany
| | - Armin Huber
- Department of Biosensorics, Institute of Physiology, University of Hohenheim, Stuttgart, Germany
| | - Olaf Voolstra
- Department of Biosensorics, Institute of Physiology, University of Hohenheim, Stuttgart, Germany
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13
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Yang C, Arrizabalaga G. The serine/threonine phosphatases of apicomplexan parasites. Mol Microbiol 2017; 106:1-21. [PMID: 28556455 DOI: 10.1111/mmi.13715] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2017] [Indexed: 12/21/2022]
Abstract
The balance between phosphorylation and de-phosphorylation, which is delicately regulated by protein kinases and phosphatases, is critical for nearly all biological processes. The Apicomplexa are a large phylum which contains various parasitic protists, including human pathogens, such as Plasmodium, Toxoplasma, Cryptosporidium and Babesia species. The diverse life cycles of these parasites are highly complex and, not surprisingly, many of their key steps are exquisitely regulated by phosphorylation. Interestingly, many of the kinases and phosphatases, as well as the substrates involved in these events are unique to the parasites and therefore phosphorylation constitutes a viable target for antiparasitic intervention. Most progress on this realm has come from studies in Toxoplasma and Plasmodium of their respective kinomes and phosphoproteomes. Nonetheless, given their likely importance, phosphatases have recently become the focus of research within the apicomplexan parasites. In this review, we concentrate on serine/threonine phosphatases in apicomplexan parasites, with the focus on comprehensively identifying and naming protein phosphatases in available apicomplexan genomes, and summarizing the progress of their functional analyses in recent years.
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Affiliation(s)
- Chunlin Yang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Gustavo Arrizabalaga
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, USA
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14
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Dees MW, Lysøe E, Alsheikh M, Davik J, Brurberg MB. Resistance to Streptomyces turgidiscabies in potato involves an early and sustained transcriptional reprogramming at initial stages of tuber formation. MOLECULAR PLANT PATHOLOGY 2016; 17:703-13. [PMID: 26416294 PMCID: PMC6638500 DOI: 10.1111/mpp.12323] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Common scab, caused by species from the bacterial genus Streptomyces, is an important disease of potato (Solanum tuberosum) crops worldwide. Early tuberization is a critical period for pathogen infection; hence, studies of host gene expression responses during this developmental stage can be important to expand our understanding of the infection process and to identify putative resistance genes. In an infection experiment with the highly susceptible potato cultivar Saturna and the relatively resistant cultivar Beate, transcription profiles were obtained by RNA sequencing at two developmental stages: the early hook stage and the early tuber formation stage. Our results indicate that 'Beate' mounts an early and sustained response to infection by S. turgidiscabies, whereas the defence response by 'Saturna' ceases before the early tuber formation stage. Most pronounced were the putative candidate defence-associated genes uniquely expressed in 'Beate'. We observed an increase in alternative splicing on pathogen infection at the early hook stage for both cultivars. A significant down-regulation of genes involved in the highly energy-demanding process of ribosome biogenesis was observed for the infected 'Beate' plants at the early hook stage, which may indicate an allocation of resources that favours the expression of defence-related genes.
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Affiliation(s)
- Merete Wiken Dees
- NIBIO, The Norwegian Institute of Bioeconomy Research, 1430, Ås, Norway
| | - Erik Lysøe
- NIBIO, The Norwegian Institute of Bioeconomy Research, 1430, Ås, Norway
| | - Muath Alsheikh
- Graminor Breeding Ltd, 2322, Ridabu, Norway
- Department of Plant Sciences, Norwegian University of Life Sciences, 1430, Ås, Norway
| | - Jahn Davik
- NIBIO, The Norwegian Institute of Bioeconomy Research, 1430, Ås, Norway
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15
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Abstract
Reversible protein phosphorylation is an essential posttranslational modification mechanism executed by opposing actions of protein phosphatases and protein kinases. About 1,000 predicted kinases in Arabidopsis thaliana kinome predominate the number of protein phosphatases, of which there are only ~150 members in Arabidopsis. Protein phosphatases were often referred to as "housekeeping" enzymes, which act to keep eukaryotic systems in balance by counteracting the activity of protein kinases. However, recent investigations reveal the crucial and specific regulatory functions of phosphatases in cell signaling. Phosphatases operate in a coordinated manner with the protein kinases, to execute their important function in determining the cellular response to a physiological stimulus. Closer examination has established high specificity of phosphatases in substrate recognition and important roles in plant signaling pathways, such as pathogen defense and stress regulation, light and hormonal signaling, cell cycle and differentiation, metabolism, and plant growth. In this minireview we provide a compact overview about Arabidopsis protein phosphatase families, as well as members of phosphoglucan and lipid phosphatases, and highlight the recent discoveries in phosphatase research.
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Affiliation(s)
- Alois Schweighofer
- Institute of Biotechnology, University of Vilnius, V. Graičiūno 8, 02241, Vilnius, Lithuania,
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16
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Uhrig RG, Labandera AM, Moorhead GB. Arabidopsis PPP family of serine/threonine protein phosphatases: many targets but few engines. TRENDS IN PLANT SCIENCE 2013; 18:505-13. [PMID: 23790269 DOI: 10.1016/j.tplants.2013.05.004] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/14/2013] [Accepted: 05/17/2013] [Indexed: 05/20/2023]
Abstract
The major plant serine/threonine protein phosphatases belong to the phosphoprotein phosphatase (PPP) family. Over the past few years the complement of Arabidopsis thaliana PPP family of catalytic subunits has been cataloged and many regulatory subunits identified. Specific roles for PPPs have been characterized, including roles in auxin and brassinosteroid signaling, in phototropism, in regulating the target of rapamycin pathway, and in cell stress responses. In this review, we provide a framework for understanding the PPP family by exploring the fundamental role of the phosphatase regulatory subunits that drive catalytic engine specificity. Although there are fewer plant protein phosphatases compared with their protein kinase partners, their function is now recognized to be as dynamic and as regulated as that of protein kinases.
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Affiliation(s)
- R Glen Uhrig
- Department of Biological Sciences, University of Calgary, Canada
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17
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Wolc A, Arango J, Jankowski T, Settar P, Fulton JE, O'Sullivan NP, Fernando R, Garrick DJ, Dekkers JCM. Genome-wide association study for Marek's disease mortality in layer chickens. Avian Dis 2013; 57:395-400. [PMID: 23901752 DOI: 10.1637/10409-100312-reg.1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A genome-wide association study (GWAS) using Bayesian variable selection was performed to determine genomic regions associated with mortality due to Marek's disease virus (MDV) infection in layers. Mortality (%) under experimental disease challenge (500 plaque-forming units of a very virulent plus MDV strain) was recorded for progeny groups (average 15.5 birds; range 3 to 30) of 253 genotyped sires from four generations of a brown-egg layer line. An additional generation of 43 sires with progeny data was used to validate results. Sires were genotyped with a 42K Illumina single-nucleotide polymorphism (SNP) chip. Methods BayesB (pi = 0.995) and BayesCpi, with or without weighting residuals by the size of progeny groups were applied. The proportion of genetic variance contributed by SNPs within each 1-megabase (Mb) genomic region was quantified. Average mortality was 33% but differed significantly between generations. Genetic markers explained about 11% of phenotypic variation in mortality. Correlations between genomic estimated breeding values and percentage of progeny mortality for the validation generation (sons of individuals in training) were 0.12, 0.17, 0.02, and 0.16 for BayesB, weighted BayesB, BayesCpi, and weighted BayesCpi, respectively, when using the whole genome, and 0.03, 0.20, -0.06, and 0.14, when using only SNP from the 10, 1-Mb regions, explaining the largest proportion of genetic variance according to each method. Results suggest that regions on chromosomes 2, 3, 4, 9, 15, 18, and 21 are associated with Marek's disease resistance and can be used for selection and that accounting for the size of progeny groups has a large impact on correct localization of such genomic regions.
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Affiliation(s)
- Anna Wolc
- Department of Genetic and Animal Breeding, Poznan University of Life Sciences, Wolynska Street 33, 60-637 Poznan, Poland.
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18
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Protein phosphatase 2A dephosphorylates SNAP-25 through two distinct mechanisms in mouse brain synaptosomes. Neurosci Res 2013; 75:184-9. [DOI: 10.1016/j.neures.2013.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 01/07/2013] [Accepted: 01/07/2013] [Indexed: 01/03/2023]
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Butler T, Paul J, Europe-Finner N, Smith R, Chan EC. Role of serine-threonine phosphoprotein phosphatases in smooth muscle contractility. Am J Physiol Cell Physiol 2013; 304:C485-504. [PMID: 23325405 DOI: 10.1152/ajpcell.00161.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The degree of phosphorylation of myosin light chain 20 (MLC20) is a major determinant of force generation in smooth muscle. Myosin phosphatases (MPs) contain protein phosphatase (PP) 1 as catalytic subunits and are the major enzymes that dephosphorylate MLC20. MP regulatory targeting subunit 1 (MYPT1), the main regulatory subunit of MP in all smooth muscles, is a key convergence point of contractile and relaxatory pathways. Combinations of regulatory mechanisms, including isoform splicing, multiple phosphorylation sites, and scaffolding proteins, modulate MYPT1 activity with tissue and agonist specificities to affect contraction and relaxation. Other members of the PP1 family that do not target myosin, as well as PP2A and PP2B, dephosphorylate a range of proteins that affect smooth muscle contraction. This review discusses the role of phosphatases in smooth muscle contractility with a focus on MYPT1 in uterine smooth muscle. Myometrium shares characteristics of vascular and other visceral smooth muscles yet, during healthy pregnancy, undergoes hypertrophy, hyperplasia, quiescence, and labor as physiological processes. Myometrium presents an accessible model for the study of normal and pathological smooth muscle function, and a better understanding of myometrial physiology may allow the development of novel therapeutics for the many disorders of myometrial physiology from preterm labor to dysmenorrhea.
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Affiliation(s)
- Trent Butler
- Mothers and Babies Research Centre, Faculty of Health, University of Newcastle, Callaghan, NSW 2308, Australia
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20
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Muñoz C, Pérez M, Orrego PR, Osorio L, Gutiérrez B, Sagua H, Castillo JL, Martínez-Oyanedel J, Arroyo R, Meza-Cervantez P, da Silveira JF, Midlej V, Benchimol M, Cordero E, Morales P, Araya JE, González J. A protein phosphatase 1 gamma (PP1γ) of the human protozoan parasite Trichomonas vaginalis is involved in proliferation and cell attachment to the host cell. Int J Parasitol 2012; 42:715-27. [PMID: 22713760 DOI: 10.1016/j.ijpara.2012.03.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 02/16/2012] [Accepted: 03/16/2012] [Indexed: 02/07/2023]
Abstract
In this work, evidence for a critical role of Trichomonas vaginalis protein phosphatase 1 gamma (TvPP1γ) in proliferation and attachment of the parasite to the mammalian cell is provided. Firstly, proliferation and attachment of T. vaginalis parasites to HeLa cells was blocked by calyculin A (CA), a potent PP1 inhibitor. Secondly, it was demonstrated that the enzyme activity of native and recombinant TvPP1γ proteins was inhibited by CA. Thirdly, reverse genetic studies confirmed that antisense oligonucleotides targeted to PP1γ but not PP1α or β inhibited proliferation and attachment of trichomonads CA-treated parasites underwent cytoskeletal modifications, including a lack of axostyle typical labelling, suggesting that cytoskeletal phosphorylation could be regulated by a CA-sensitive phosphatase where the role of PP1γ could not be ruled out. Analysis of subcellular distribution of TvPP1γ by cell fractionation and electron microscopy demonstrated the association between TvPP1γ and the cytoskeleton. The expression of adhesins, AP120 and AP65, at the cell surface was also inhibited by CA. The concomitant inhibition of expression of adhesins and changes in the cytoskeleton in CA-treated parasites suggest a specific role for PP1γ -dependent dephosphorylation in the early stages of the host-parasite interaction. Molecular modelling of TvPP1γ showed the conservation of residues critical for maintaining proper folding into the gross structure common to PP1 proteins. Taken together, these results suggest that TvPP1γ could be considered a potential novel drug target for treatment of trichomoniasis.
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Affiliation(s)
- Christian Muñoz
- Department of Medical Technology, University of Antofagasta, Antofagasta, P.O. Box 170, Chile
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21
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Abstract
Cell death is regulated by a myriad of intracellular molecular pathways, with many involving protein phosphorylation and dephosphorylation. In this review, we will focus on Ser/Thr phosphatases-mediated regulation in cell apoptosis as well as on their potential roles in cell necrosis. The emerging functional importance of Ser/Thr protein phosphatases in cell death regulation adds new dimension to the signaling mechanisms of cellular function, physiology, and diseases.
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Affiliation(s)
- Haipeng Sun
- Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Department of Pathophysiology, Shanghai Jiaotong University School of Medicine, Shanghai, China
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22
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Kinases, phosphatases and proteases during sperm capacitation. Cell Tissue Res 2012; 349:765-82. [DOI: 10.1007/s00441-012-1370-3] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 02/07/2012] [Indexed: 12/17/2022]
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23
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Fardilha M, Esteves SLC, Korrodi-Gregório L, Pelech S, da Cruz E Silva OAB, da Cruz E Silva E. Protein phosphatase 1 complexes modulate sperm motility and present novel targets for male infertility. Mol Hum Reprod 2011; 17:466-77. [PMID: 21257602 DOI: 10.1093/molehr/gar004] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Infertility is a growing concern in modern society, with 30% of cases being due to male factors, namely reduced sperm concentration, decreased motility and abnormal morphology. Sperm cells are highly compartmentalized, almost devoid of transcription and translation consequently processes such as protein phosphorylation provide a key general mechanism for regulating vital cellular functions, more so than for undifferentiated cells. Reversible protein phosphorylation is the principal mechanism regulating most physiological processes in eukaryotic cells. To date, hundreds of protein kinases have been identified, but significantly fewer phosphatases (PPs) are responsible for counteracting their action. This discrepancy can be explained in part by the mechanism used to control phosphatase activity, which is based on regulatory interacting proteins. This is particularly true for PP1, a major serine/threonine-PP, for which >200 interactors (PP1 interacting proteins-PIPs) have been indentified that control its activity, subcellular location and substrate specificity. For PP1, several isoforms have been described, among them PP1γ2, a testis/sperm-enriched PP1 isoform. Recent findings support our hypothesis that PP1γ2 is involved in the regulation of sperm motility. This review summarizes the known sperm-specific PP1-PIPs, involved in the acquisition of mammalian sperm motility. The complexes that PP1 routinely forms with different proteins are addressed and the role of PP1/A-kinase anchoring protein complexes in sperm motility is considered. Furthermore, the potential relevance of targeting PP1-PIPs complexes to infertility diagnostics and therapeutics as well as to male contraception is also discussed.
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Affiliation(s)
- Margarida Fardilha
- Signal Transduction Laboratory, Centre for Cell Biology, Health Sciences Department and Biology Department, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
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Kutuzov MA, Bennett N, Andreeva AV. Protein phosphatase with EF-hand domains 2 (PPEF2) is a potent negative regulator of apoptosis signal regulating kinase-1 (ASK1). Int J Biochem Cell Biol 2010; 42:1816-22. [PMID: 20674765 DOI: 10.1016/j.biocel.2010.07.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 07/09/2010] [Accepted: 07/21/2010] [Indexed: 11/28/2022]
Abstract
The function of protein phosphatases with EF-hand domains (PPEF) in mammals is not known. Large-scale expression profiling experiments suggest that PPEF expression may correlate with stress protective responses, cell survival, growth, proliferation, or neoplastic transformation. Apoptosis signal regulating kinase-1 (ASK1) is a MAP kinase kinase kinase implicated in cancer, cardiovascular and neurodegenerative diseases. ASK1 is activated by oxidative stress and induces pro-apoptotic or inflammatory signalling, largely via sustained activation of MAP kinases p38 and/or JNK. We identify human PPEF2 as a novel interacting partner and a negative regulator of ASK1. In COS-7 or HEK 293A cells treated with H(2)O(2), expression of PPEF2 abrogated sustained activation of p38 and one of the JNK p46 isoforms, and prevented ASK1-dependent caspase-3 cleavage and activation. PPEF2 efficiently suppressed H(2)O(2)-induced activation of ASK1. Overexpessed as well as endogenous ASK1 co-immunoprecipitated with PPEF2. PPEF2 was considerably more potent both as a suppressor of ASK1 activation and as its interacting partner as compared to protein phosphatase 5 (PP5), a well-known negative regulator of ASK1. PPEF2 was found to form complexes with endogenous Hsp70 and to a lesser extent Hsp90, which are also known interacting partners of PP5. These data identify, for the first time, a possible downstream signalling partner of a mammalian PPEF phosphatase, and suggest that, despite structural divergence, PPEF and PP5 phosphatases may share common interacting partners and functions.
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Affiliation(s)
- Mikhail A Kutuzov
- Department of Pharmacology (MC 868), University of Illinois at Chicago, Chicago, IL 60612, USA.
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