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Monagas-Valentin P, Bridger R, Chandel I, Koff M, Novikov B, Schroeder P, Wells L, Panin V. Protein tyrosine phosphatase 69D is a substrate of protein O-mannosyltransferases 1-2 that is required for the wiring of sensory axons in Drosophila. J Biol Chem 2023; 299:102890. [PMID: 36634851 PMCID: PMC9950532 DOI: 10.1016/j.jbc.2023.102890] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 12/29/2022] [Accepted: 12/30/2022] [Indexed: 01/11/2023] Open
Abstract
Mutations in protein O-mannosyltransferases (POMTs) result in severe brain defects and congenital muscular dystrophies characterized by abnormal glycosylation of α-dystroglycan (α-Dg). However, neurological phenotypes of POMT mutants are not well understood, and the functional substrates of POMTs other than α-Dg remain unknown. Using a Drosophila model, here we reveal that Dg alone cannot account for the phenotypes of POMT mutants, and identify Protein tyrosine phosphatase 69D (PTP69D) as a gene interacting with POMTs in producing the abdomen rotation phenotype. Using RNAi-mediated knockdown, mutant alleles, and a dominant-negative form of PTP69D, we reveal that PTP69D is required for the wiring of larval sensory axons. We also found that PTP69D and POMT genes interact in this process, and that their interactions lead to complex synergistic or antagonistic effects on axon wiring phenotypes, depending on the mode of genetic manipulation. Using glycoproteomic approaches, we further characterized the glycosylation of the PTP69D transgenic construct expressed in genetic strains with different levels of POMT activity. We found that the PTP69D construct carries many O-linked mannose modifications when expressed in Drosophila with wild-type or ectopically upregulated expression of POMTs. These modifications were absent in POMT mutants, suggesting that PTP69D is a substrate of POMT-mediated O-mannosylation. Taken together, our results indicate that PTP69D is a novel functional substrate of POMTs that is required for axon connectivity. This mechanism of POMT-mediated regulation of receptor-type protein tyrosine phosphatase functions could potentially be conserved in mammals and may shed new light on the etiology of neurological defects in muscular dystrophies.
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Affiliation(s)
- Pedro Monagas-Valentin
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, Texas, USA
| | - Robert Bridger
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - Ishita Chandel
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, Texas, USA
| | - Melissa Koff
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, Texas, USA
| | - Boris Novikov
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, Texas, USA
| | - Patrick Schroeder
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, Texas, USA
| | - Lance Wells
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, USA
| | - Vladislav Panin
- Department of Biochemistry and Biophysics, AgriLife Research, Texas A&M University, College Station, Texas, USA.
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2
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Ma W, Zhu L, Song S, Liu B, Gu J. Identification and Validation of Glycosyltransferases Correlated with Cuproptosis as a Prognostic Model for Colon Adenocarcinoma. Cells 2022; 11:cells11233728. [PMID: 36496988 PMCID: PMC9737711 DOI: 10.3390/cells11233728] [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: 10/31/2022] [Revised: 11/14/2022] [Accepted: 11/18/2022] [Indexed: 11/24/2022] Open
Abstract
Cuproptosis is a newly defined programmed cell death pattern and is believed to play an important role in tumorigenesis and progression. In addition, many studies have shown that glycosylation modification is of vital importance in tumor progression. However, it remains unclear whether glycosyltransferases, the most critical enzymes involved in glycosylation modification, are associated with cuproptosis. In this study, we used bioinformatic methods to construct a signature of cuproptosis-related glycosyltransferases to predict the prognosis of colon adenocarcinoma patients. We found that cuproptosis was highly correlated with four glycosyltransferases in COAD, and our model predicted the prognosis of COAD patients. Further analysis of related functions revealed the possibility that cuproptosis-related glycosyltransferase Exostosin-like 2 (EXTL2) participated in tumor immunity.
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Affiliation(s)
| | | | | | - Bo Liu
- Correspondence: (S.S.); (B.L.)
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3
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Chen XY, Song DY, Jiang L, Tan DD, Liu YD, Liu JY, Chang XZ, Xing GG, Toda T, Xiong H. Phenotype and Genotype Study of Chinese POMT2-Related α-Dystroglycanopathy. Front Genet 2021; 12:692479. [PMID: 34413876 PMCID: PMC8370027 DOI: 10.3389/fgene.2021.692479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 07/09/2021] [Indexed: 11/25/2022] Open
Abstract
Objective Alpha-dystroglycanopathy (α-DGP) is a subtype of muscular dystrophy caused by defects in the posttranslational glycosylation of α-dystroglycan (α-DG). Our study aimed to summarize the clinical and genetic features of POMT2-related α-DGP in a cohort of patients in China. Methods Pedigrees, clinical data, and laboratory tests of patients diagnosed with POMT2-related α-DGP were analyzed retrospectively. The pathogenicity of variants in POMT2 were predicted by bioinformatics software. The variants with uncertain significance were verified by further analysis. Results The 11 patients, comprising eight males and three females, were from nine non-consanguineous families. They exhibited different degrees of muscle weakness, ambulation, and intellectual impairment. Among them, three had a muscle-eye-brain disease (MEB)-like phenotype, five presented congenital muscular dystrophy with intellectual disability (CMD-ID), and three presented limb-girdle muscular dystrophy (LGMD). Overall, nine novel variants of POMT2, including two non-sense, one frameshift and six missense variants, were identified. The pathogenicity of two missense variants, c.1891G > C and c.874G > C, was uncertain based on bioinformatics software prediction. In vitro minigene analysis showed that c.1891G > C affects the splicing of POMT2. Immunofluorescence staining with the IIH6C4 antibody of muscle biopsy from the patient carrying the c.874G > C variant showed an apparent lack of expression. Conclusion This study summarizes the clinical and genetic characteristics of a cohort of POMT2-related α-DGP patients in China for the first time, expanding the mutational spectrum of the disease. Further study of the pathogenicity of some missense variants based on enzyme activity detection is needed.
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Affiliation(s)
- Xiao-Yu Chen
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Dan-Yu Song
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Li Jiang
- Department of Neurology, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Dan-Dan Tan
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yi-Dan Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Jie-Yu Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xing-Zhi Chang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Guo-Gang Xing
- Department of Neurobiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Tatsushi Toda
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hui Xiong
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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4
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Wen Z, Tian H, Xia Y, Jin K. MaPmt1, a protein O-mannosyltransferase, contributes to virulence through governing the appressorium turgor pressure in Metarhizium acridum. Fungal Genet Biol 2020; 145:103480. [DOI: 10.1016/j.fgb.2020.103480] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 10/19/2020] [Accepted: 10/23/2020] [Indexed: 12/24/2022]
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5
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Ferent J, Zaidi D, Francis F. Extracellular Control of Radial Glia Proliferation and Scaffolding During Cortical Development and Pathology. Front Cell Dev Biol 2020; 8:578341. [PMID: 33178693 PMCID: PMC7596222 DOI: 10.3389/fcell.2020.578341] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/08/2020] [Indexed: 01/14/2023] Open
Abstract
During the development of the cortex, newly generated neurons migrate long-distances in the expanding tissue to reach their final positions. Pyramidal neurons are produced from dorsal progenitors, e.g., radial glia (RGs) in the ventricular zone, and then migrate along RG processes basally toward the cortex. These neurons are hence dependent upon RG extensions to support their migration from apical to basal regions. Several studies have investigated how intracellular determinants are required for RG polarity and subsequent formation and maintenance of their processes. Fewer studies have identified the influence of the extracellular environment on this architecture. This review will focus on extracellular factors which influence RG morphology and pyramidal neuronal migration during normal development and their perturbations in pathology. During cortical development, RGs are present in different strategic positions: apical RGs (aRGs) have their cell bodies located in the ventricular zone with an apical process contacting the ventricle, while they also have a basal process extending radially to reach the pial surface of the cortex. This particular conformation allows aRGs to be exposed to long range and short range signaling cues, whereas basal RGs (bRGs, also known as outer RGs, oRGs) have their cell bodies located throughout the cortical wall, limiting their access to ventricular factors. Long range signals impacting aRGs include secreted molecules present in the embryonic cerebrospinal fluid (e.g., Neuregulin, EGF, FGF, Wnt, BMP). Secreted molecules also contribute to the extracellular matrix (fibronectin, laminin, reelin). Classical short range factors include cell to cell signaling, adhesion molecules and mechano-transduction mechanisms (e.g., TAG1, Notch, cadherins, mechanical tension). Changes in one or several of these components influencing the RG extracellular environment can disrupt the development or maintenance of RG architecture on which neuronal migration relies, leading to a range of cortical malformations. First, we will detail the known long range signaling cues impacting RG. Then, we will review how short range cell contacts are also important to instruct the RG framework. Understanding how RG processes are structured by their environment to maintain and support radial migration is a critical part of the investigation of neurodevelopmental disorders.
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Affiliation(s)
- Julien Ferent
- Inserm, U 1270, Paris, France.,Sorbonne University, UMR-S 1270, IFM, Paris, France.,Institut du Fer á Moulin, Paris, France
| | - Donia Zaidi
- Inserm, U 1270, Paris, France.,Sorbonne University, UMR-S 1270, IFM, Paris, France.,Institut du Fer á Moulin, Paris, France
| | - Fiona Francis
- Inserm, U 1270, Paris, France.,Sorbonne University, UMR-S 1270, IFM, Paris, France.,Institut du Fer á Moulin, Paris, France
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6
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Mahjoub G, Faghihi MA, Taghdiri M. Reporting one very rare pathogenic variation c.1106G>A in POMT2 gene. Intractable Rare Dis Res 2020; 9:104-108. [PMID: 32494558 PMCID: PMC7263986 DOI: 10.5582/irdr.2020.03013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Dystroglycan (DG) is a major cell membrane glycoprotein, which is encoded by the DAG1 gene. α-DG is one of DG subunits, belongs to O-mannosylated protein of mammals and was identified in brain, peripheral nerves and muscle. Dystroglycanopathies are a group of heterogeneous congenital muscular dystrophies, which can result from defective α-DG mannosylation. First line of α-DG glycosylation is catalyzed by protein O-mannosyltransferase family (PMT). In this study, the mutation was identified in the POMT2 gene, which encodes O-mannosyltransferase 2 protein and its mutations can be contributed to dystroglycanopathies. A very rare missense mutation in the POMT2 gene (NM_013382: exon9: c. 1106G>A) was identified by next generation sequencing (NGS) and was subsequently confirmed using Sanger sequencing in both affected siblings. There was no report of this mutation in the literature, therefore, the significance was uncertain. Our findings confirmed the pathogenicity of mutation and expanded the mutation spectrum of POMT2, which will be helpful in further molecular evaluations of muscular diseases.
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Affiliation(s)
- Ghazale Mahjoub
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Ali Faghihi
- Persian BayanGene Research and Training Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Center for Therapeutic Innovation, Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Miami, USA
| | - Maryam Taghdiri
- Genetic Counseling Center, Shiraz Welfare Organization, Shiraz, Iran
- Comprehensive Medical Genetic Center, Shiraz University of Medical Sciences, Shiraz, Iran
- Address correspondence to:Maryam Taghdiri, Genetic Counseling Center, Shiraz Welfare Organization, Shiraz, Iran and Comprehensive Medical Genetic Center, Shiraz University of Medical Sciences, Shiraz, Iran. E-mail:
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Castells-Ballester J, Rinis N, Kotan I, Gal L, Bausewein D, Kats I, Zatorska E, Kramer G, Bukau B, Schuldiner M, Strahl S. Translational Regulation of Pmt1 and Pmt2 by Bfr1 Affects Unfolded Protein O-Mannosylation. Int J Mol Sci 2019; 20:ijms20246220. [PMID: 31835530 PMCID: PMC6940804 DOI: 10.3390/ijms20246220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/05/2019] [Accepted: 12/06/2019] [Indexed: 12/15/2022] Open
Abstract
O-mannosylation is implicated in protein quality control in Saccharomyces cerevisiae due to the attachment of mannose to serine and threonine residues of un- or misfolded proteins in the endoplasmic reticulum (ER). This process also designated as unfolded protein O-mannosylation (UPOM) that ends futile folding cycles and saves cellular resources is mainly mediated by protein O-mannosyltransferases Pmt1 and Pmt2. Here we describe a genetic screen for factors that influence O-mannosylation in yeast, using slow-folding green fluorescent protein (GFP) as a reporter. Our screening identifies the RNA binding protein brefeldin A resistance factor 1 (Bfr1) that has not been linked to O-mannosylation and ER protein quality control before. We find that Bfr1 affects O-mannosylation through changes in Pmt1 and Pmt2 protein abundance but has no effect on PMT1 and PMT2 transcript levels, mRNA localization to the ER membrane or protein stability. Ribosome profiling reveals that Bfr1 is a crucial factor for Pmt1 and Pmt2 translation thereby affecting unfolded protein O-mannosylation. Our results uncover a new level of regulation of protein quality control in the secretory pathway.
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Affiliation(s)
- Joan Castells-Ballester
- Centre for Organismal Studies (COS), Glycobiology, Heidelberg University, D-69120 Heidelberg, Germany; (J.C.-B.); (N.R.); (D.B.); (E.Z.)
| | - Natalie Rinis
- Centre for Organismal Studies (COS), Glycobiology, Heidelberg University, D-69120 Heidelberg, Germany; (J.C.-B.); (N.R.); (D.B.); (E.Z.)
| | - Ilgin Kotan
- Center for Molecular Biology of Heidelberg University (ZMBH), German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance, D-69120 Heidelberg, Germany; (I.K.); (I.K.); (G.K.); (B.B.)
| | - Lihi Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel; (L.G.); (M.S.)
| | - Daniela Bausewein
- Centre for Organismal Studies (COS), Glycobiology, Heidelberg University, D-69120 Heidelberg, Germany; (J.C.-B.); (N.R.); (D.B.); (E.Z.)
- spm—Safety Projects & More GmbH, D-69493 Hirschberg a. d. Bergstraße, Germany
| | - Ilia Kats
- Center for Molecular Biology of Heidelberg University (ZMBH), German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance, D-69120 Heidelberg, Germany; (I.K.); (I.K.); (G.K.); (B.B.)
| | - Ewa Zatorska
- Centre for Organismal Studies (COS), Glycobiology, Heidelberg University, D-69120 Heidelberg, Germany; (J.C.-B.); (N.R.); (D.B.); (E.Z.)
| | - Günter Kramer
- Center for Molecular Biology of Heidelberg University (ZMBH), German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance, D-69120 Heidelberg, Germany; (I.K.); (I.K.); (G.K.); (B.B.)
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University (ZMBH), German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance, D-69120 Heidelberg, Germany; (I.K.); (I.K.); (G.K.); (B.B.)
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel; (L.G.); (M.S.)
| | - Sabine Strahl
- Centre for Organismal Studies (COS), Glycobiology, Heidelberg University, D-69120 Heidelberg, Germany; (J.C.-B.); (N.R.); (D.B.); (E.Z.)
- Correspondence: ; Tel.: +49-6221-54-6286
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8
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Khawar MB, Gao H, Li W. Mechanism of Acrosome Biogenesis in Mammals. Front Cell Dev Biol 2019; 7:195. [PMID: 31620437 PMCID: PMC6759486 DOI: 10.3389/fcell.2019.00195] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/29/2019] [Indexed: 11/13/2022] Open
Abstract
During sexual reproduction, two haploid gametes fuse to form the zygote, and the acrosome is essential to this fusion process (fertilization) in animals. The acrosome is a special kind of organelle with a cap-like structure that covers the anterior portion of the head of the spermatozoon. The acrosome is derived from the Golgi apparatus and contains digestive enzymes. With the progress of our understanding of acrosome biogenesis, a number of models have been proposed to address the origin of the acrosome. The acrosome has been regarded as a lysosome-related organelle, and it has been proposed to have originated from the lysosome or the autolysosome. Our review will provide a brief historical overview and highlight recent findings on acrosome biogenesis in mammals.
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Affiliation(s)
- Muhammad Babar Khawar
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hui Gao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Wei Li
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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9
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Li S, Sun P, Gong X, Chang S, Li E, Xu Y, Wu J, Liu B. Engineering O-glycosylation in modified N-linked oligosaccharide (Man 12GlcNAc 2∼Man 16GlcNAc 2) Pichia pastoris strains. RSC Adv 2019; 9:8246-8252. [PMID: 35518704 PMCID: PMC9061240 DOI: 10.1039/c8ra08121b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 02/19/2019] [Indexed: 11/24/2022] Open
Abstract
Yeast have been engineered for the production of therapeutic glycoproteins with humanized N-linked oligosaccharides. Both N- and O-linked oligosaccharides engineered yeast have been attractive prospects, since yeast-specific O-mannosylated proteins were reported to induce an aberrant immune response and alter pharmacokinetics in vivo. In the present study, we genetically manipulated O-glycosylation by disrupting O-mannosyltransferase PMT1 and PMT5 in a low-mannose type N-linked oligosaccharide (Man12GlcNAc2∼Man16GlcNAc2) engineered Pichia pastoris strain to produce therapeutic glycoproteins. The O-mannosyltransferase PMT1 mutant produces anti-Her-2 antibodies with reduced O-linked oligosaccharides and protein degradation, but this strain exhibited growth defects. However, the deletion of O-mannosyltransferase PMT5 individually has a minimal effect on O-glycosylation, degradation of the anti-Her-2 antibody, and strain growth. Thus, by disrupting O-mannosyltransferase PMT1 in an N-glycosylation engineered Pichia pastoris strain, we generated an effective glycoengineered Pichia pastoris strain to effectively produce therapeutic glycoproteins with both engineered N- and O-linked oligosaccharides.
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Affiliation(s)
- Siqiang Li
- Beijing Institute of Biotechnology Beijing 100071 China +861063833521
- School of Biological and Food Engineering, Huanghuai University Zhumadian 463000 China
| | - Peng Sun
- Beijing Institute of Biotechnology Beijing 100071 China +861063833521
| | - Xin Gong
- Beijing Institute of Biotechnology Beijing 100071 China +861063833521
| | - Shaohong Chang
- Beijing Institute of Biotechnology Beijing 100071 China +861063833521
| | - Enzhong Li
- School of Biological and Food Engineering, Huanghuai University Zhumadian 463000 China
| | - Yuanhong Xu
- School of Biological and Food Engineering, Huanghuai University Zhumadian 463000 China
| | - Jun Wu
- Beijing Institute of Biotechnology Beijing 100071 China +861063833521
| | - Bo Liu
- Beijing Institute of Biotechnology Beijing 100071 China +861063833521
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10
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Le THT, Oki A, Goto M, Shimizu K. Protein O-mannosyltransferases are required for sterigmatocystin production and developmental processes in Aspergillus nidulans. Curr Genet 2018; 64:1043-1056. [DOI: 10.1007/s00294-018-0816-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 02/19/2018] [Accepted: 02/20/2018] [Indexed: 12/19/2022]
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O-mannosylation and N-glycosylation: two coordinated mechanisms regulating the tumour suppressor functions of E-cadherin in cancer. Oncotarget 2018; 7:65231-65246. [PMID: 27533452 PMCID: PMC5323151 DOI: 10.18632/oncotarget.11245] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 08/01/2016] [Indexed: 11/25/2022] Open
Abstract
Dysregulation of tumor suppressor protein E-cadherin is an early molecular event in cancer. O-mannosylation profile of E-cadherin is a newly-described post-translational modification crucial for its adhesive functions in homeostasis. However, the role of O-mannosyl glycans in E-cadherin-mediated cell adhesion in cancer and their interplay with N-glycans remains largely unknown. We herein demonstrated that human gastric carcinomas exhibiting a non-functional E-cadherin display a reduced expression of O-mannosyl glycans concomitantly with increased modification with branched complex N-glycans. Accordingly, overexpression of MGAT5-mediated branched N-glycans both in gastric cancer cells and transgenic mice models led to a significant decrease of O-mannosyl glycans attached to E-cadherin that was associated with impairment of its tumour suppressive functions. Importantly, overexpression of protein O-mannosyltransferase 2 (POMT2) induced a reduced expression of branched N-glycans which led to a protective effect of E-cadherin biological functions. Overall, our results reveal a newly identified mechanism of (dys)regulation of E-cadherin that occur through the interplay between O-mannosylation and N-glycosylation pathway.
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12
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Discovery of an O-mannosylation pathway selectively serving cadherins and protocadherins. Proc Natl Acad Sci U S A 2017; 114:11163-11168. [PMID: 28973932 DOI: 10.1073/pnas.1708319114] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The cadherin (cdh) superfamily of adhesion molecules carry O-linked mannose (O-Man) glycans at highly conserved sites localized to specific β-strands of their extracellular cdh (EC) domains. These O-Man glycans do not appear to be elongated like O-Man glycans found on α-dystroglycan (α-DG), and we recently demonstrated that initiation of cdh/protocadherin (pcdh) O-Man glycosylation is not dependent on the evolutionary conserved POMT1/POMT2 enzymes that initiate O-Man glycosylation on α-DG. Here, we used a CRISPR/Cas9 genetic dissection strategy combined with sensitive and quantitative O-Man glycoproteomics to identify a homologous family of four putative protein O-mannosyltransferases encoded by the TMTC1-4 genes, which were found to be imperative for cdh and pcdh O-Man glycosylation. KO of all four TMTC genes in HEK293 cells resulted in specific loss of cdh and pcdh O-Man glycosylation, whereas combined KO of TMTC1 and TMTC3 resulted in selective loss of O-Man glycans on specific β-strands of EC domains, suggesting that each isoenzyme serves a different function. In addition, O-Man glycosylation of IPT/TIG domains of plexins and hepatocyte growth factor receptor was not affected in TMTC KO cells, suggesting the existence of yet another O-Man glycosylation machinery. Our study demonstrates that regulation of O-mannosylation in higher eukaryotes is more complex than envisioned, and the discovery of the functions of TMTCs provide insight into cobblestone lissencephaly caused by deficiency in TMTC3.
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13
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Analysis of phenotype, enzyme activity and genotype of Chinese patients with POMT1 mutation. J Hum Genet 2016; 61:753-9. [PMID: 27193224 DOI: 10.1038/jhg.2016.42] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 03/04/2016] [Accepted: 03/30/2016] [Indexed: 01/20/2023]
Abstract
Protein O-mannosyltransferase 1 (POMT1) is a glycosyltransferase involved in α-dystroglycan glycosylation. POMT1 mutations cause a wide spectrum of clinical conditions from Walker-Warburg syndrome (WWS), which involves muscle, eye and brain abnormalities, to mild forms of limb-girdle muscular dystrophy with mental retardation. We aimed to elucidate the impact of different POMT1 mutations on the clinical phenotype. We report five Chinese patients with POMT1 mutations: one had a typical clinical manifestation of WWS, and the other four were diagnosed with congenital muscular dystrophy with mental retardation of varying severity. We analyzed the influence of the POMT1 mutations on POMT activity by assaying the patients' muscles and cultured skin fibroblasts. We demonstrated different levels of decreased POMT activity that correlated highly with decreased α-dystroglycan glycosylation. Our results suggest that POMT activity is inversely proportional to clinical severity, and demonstrate that skin fibroblasts can be used for differential diagnosis of patients with α-dystroglycanopathies. We have provided clinical, histological, enzymatic and genetic evidence of POMT1 involvement in five unrelated Chinese patients.
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Abstract
The dystrophin complex stabilizes the plasma membrane of striated muscle cells. Loss of function mutations in the genes encoding dystrophin, or the associated proteins, trigger instability of the plasma membrane, and myofiber loss. Mutations in dystrophin have been extensively cataloged, providing remarkable structure-function correlation between predicted protein structure and clinical outcomes. These data have highlighted dystrophin regions necessary for in vivo function and fueled the design of viral vectors and now, exon skipping approaches for use in dystrophin restoration therapies. However, dystrophin restoration is likely more complex, owing to the role of the dystrophin complex as a broad cytoskeletal integrator. This review will focus on dystrophin restoration, with emphasis on the regions of dystrophin essential for interacting with its associated proteins and discuss the structural implications of these approaches.
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Affiliation(s)
- Quan Q Gao
- Committee on Development, Regeneration and Stem Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Elizabeth M McNally
- Center for Genetic Medicine, Northwestern University, Chicago, Chicago, Illinois, USA
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15
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Xu C, Ng DTW. Glycosylation-directed quality control of protein folding. Nat Rev Mol Cell Biol 2015; 16:742-52. [PMID: 26465718 DOI: 10.1038/nrm4073] [Citation(s) in RCA: 255] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Membrane-bound and soluble proteins of the secretory pathway are commonly glycosylated in the endoplasmic reticulum. These adducts have many biological functions, including, notably, their contribution to the maturation of glycoproteins. N-linked glycans are of oligomeric structure, forming configurations that provide blueprints to precisely instruct the folding of protein substrates and the quality control systems that scrutinize it. O-linked mannoses are simpler in structure and were recently found to have distinct functions in protein quality control that do not require the complex structure of N-linked glycans. Together, recent studies reveal the breadth and sophistication of the roles of these glycan-directed modifications in protein biogenesis.
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Affiliation(s)
- Chengchao Xu
- Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604.,Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543
| | - Davis T W Ng
- Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604.,Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543.,Duke University-National University of Singapore Graduate Medical School, 8 College Road, Singapore 169857
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16
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Kim H, Thak EJ, Lee DJ, Agaphonov MO, Kang HA. Hansenula polymorpha Pmt4p Plays Critical Roles in O-Mannosylation of Surface Membrane Proteins and Participates in Heteromeric Complex Formation. PLoS One 2015; 10:e0129914. [PMID: 26134523 PMCID: PMC4489896 DOI: 10.1371/journal.pone.0129914] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/14/2015] [Indexed: 01/09/2023] Open
Abstract
O-mannosylation, the addition of mannose to serine and threonine residues of secretory proteins, is a highly conserved post-translational modification found in organisms ranging from bacteria to humans. Here, we report the functional and molecular characterization of the HpPMT4 gene encoding a protein O-mannosyltransferase in the thermotolerant methylotrophic yeast Hansenula polymorpha, an emerging host for the production of therapeutic recombinant proteins. Compared to the deletion of HpPMT1, deletion of another major PMT gene, HpPMT4, resulted in more increased sensitivity to the antibiotic hygromycin B, caffeine, and osmotic stresses, but did not affect the thermotolerance of H. polymorpha. Notably, the deletion of HpPMT4 generated severe defects in glycosylation of the surface sensor proteins HpWsc1p and HpMid2p, with marginal effects on secreted glycoproteins such as chitinase and HpYps1p lacking a GPI anchor. However, despite the severely impaired mannosylation of surface sensor proteins in the Hppmt4∆ mutant, the phosphorylation of HpMpk1p and HpHog1p still showed a high increase upon treatment with cell wall disturbing agents or high concentrations of salts. The conditional Hppmt1pmt4∆ double mutant strains displayed severely impaired growth, enlarged cell size, and aberrant cell separation, implying that the loss of HpPMT4 function might be lethal to cells in the absence of HpPmt1p. Moreover, the HpPmt4 protein was found to form not only a homomeric complex but also a heteromeric complex with either HpPmt1p or HpPmt2p. Altogether, our results support the function of HpPmt4p as a key player in O-mannosylation of cell surface proteins and its participation in the formation of heterodimers with other PMT members, besides homodimer formation, in H. polymorpha.
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Affiliation(s)
- Hyunah Kim
- Department of Life Science, Chung-Ang University, Seoul 156–756, Korea
| | - Eun Jung Thak
- Department of Life Science, Chung-Ang University, Seoul 156–756, Korea
| | - Dong-Jik Lee
- Department of Life Science, Chung-Ang University, Seoul 156–756, Korea
| | - Michael O. Agaphonov
- A.N. Bach Institute of Biochemistry of the Russian Academy of Sciences, Moscow, Russia
| | - Hyun Ah Kang
- Department of Life Science, Chung-Ang University, Seoul 156–756, Korea
- * E-mail:
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17
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Xu C, Ng DT. O-mannosylation: The other glycan player of ER quality control. Semin Cell Dev Biol 2015; 41:129-34. [DOI: 10.1016/j.semcdb.2015.01.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 01/30/2015] [Indexed: 01/07/2023]
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18
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Abstract
Most proteins are modified by glycans, which can modulate the biological properties and functions of glycoproteins. The major glycans can be classified into N-glycans and O-glycans according to their glycan-peptide linkage. This review will provide an overview of the O-mannosyl glycans, one subtype of O-glycans. Originally, O-mannosyl glycan was only known to be present on a limited number of glycoproteins, especially α-dystroglycan (α-DG). However, once a clear relationship was established between O-mannosyl glycan and the pathological mechanisms of some congenital muscular dystrophies in humans, research on the biochemistry and pathology of O-mannosyl glycans has been expanding. Because α-DG glycosylation is defective in congenital muscular dystrophies, which also feature abnormal neuronal migration, these disorders are collectively called α-dystroglycanopathies. In this article, I will describe the structure, biosynthesis and pathology of O-mannosyl glycans.
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Affiliation(s)
- Tamao Endo
- Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo 173-0015, Japan
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19
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González M, Brito N, González C. Identification of glycoproteins secreted by wild-type Botrytis cinerea and by protein O-mannosyltransferase mutants. BMC Microbiol 2014; 14:254. [PMID: 25305780 PMCID: PMC4197228 DOI: 10.1186/s12866-014-0254-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 09/24/2014] [Indexed: 11/10/2022] Open
Abstract
Background Botrytis cinerea secretes a high number of proteins that are predicted to have numerous O-glycosylation sites, frequently grouped in highly O-glycosylated regions, and analysis of mutants affected in O-glycosylation has shown, in B. cinerea and in other phytopathogenic fungi, that this process is important for fungal biology and virulence. Results We report here the purification of glycoproteins from the culture medium, for a wild-type strain of B. cinerea and for three mutants affected in the first step of O-glycosylation, and the identification of components in the purified protein samples. Overall, 158 proteins were identified belonging to a wide diversity of protein families, which possess Ser/Thr-rich regions (presumably highly O-glycosylated) twice as frequently as the whole secretome. Surprisingly, proteins predicted to be highly O-glycosylated tend to be more abundant in the secretomes of the mutants affected in O-glycosylation than in the wild type, possibly because a correct glycosylation of these proteins helps keep them in the cell wall or extracellular matrix. Overexpression of three proteins predicted to be O-glycosylated in various degrees allowed to confirm the presence of mannose α1-2 and/or α1-3 bonds, but no mannose α1-6 bonds, and resulted in an enhanced activity of the culture medium to elicit plant defenses. Conclusions Glycosylation of secretory proteins is very prevalent in B. cinerea and affects members of diverse protein families. O-glycosylated proteins play a role in the elicitation of plant defenses. Electronic supplementary material The online version of this article (doi:10.1186/s12866-014-0254-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Mario González
- U.D. Bioquímica y Biología Molecular, Universidad de La Laguna, 38206, La Laguna (Tenerife), Spain.
| | - Nélida Brito
- U.D. Bioquímica y Biología Molecular, Universidad de La Laguna, 38206, La Laguna (Tenerife), Spain.
| | - Celedonio González
- U.D. Bioquímica y Biología Molecular, Universidad de La Laguna, 38206, La Laguna (Tenerife), Spain.
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20
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Townsend D. Finding the sweet spot: assembly and glycosylation of the dystrophin-associated glycoprotein complex. Anat Rec (Hoboken) 2014; 297:1694-705. [PMID: 25125182 PMCID: PMC4135523 DOI: 10.1002/ar.22974] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/27/2014] [Indexed: 01/12/2023]
Abstract
The dystrophin-associated glycoprotein complex (DGC) is a collection of glycoproteins that are essential for the normal function of striated muscle and many other tissues. Recent genetic studies have implicated the components of this complex in over a dozen forms of muscular dystrophy. Furthermore, disruption of the DGC has been implicated in many forms of acquired disease. This review aims to summarize the current state of knowledge regarding the processing and assembly of dystrophin-associated proteins with a focus primarily on the dystroglycan heterodimer and the sarcoglycan complex. These proteins form the transmembrane portion of the DGC and undergo a complex multi-step processing with proteolytic cleavage, differential assembly, and both N- and O-glycosylation. The enzymes responsible for this processing and a model describing the sequence and subcellular localization of these events are discussed.
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Affiliation(s)
- Dewayne Townsend
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota
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21
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Comparative Analysis of Protein Glycosylation Pathways in Humans and the Fungal Pathogen Candida albicans. Int J Microbiol 2014; 2014:267497. [PMID: 25104959 PMCID: PMC4106090 DOI: 10.1155/2014/267497] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/06/2014] [Indexed: 11/30/2022] Open
Abstract
Protein glycosylation pathways are present in all kingdoms of life and are metabolic pathways found in all the life kingdoms. Despite sharing commonalities in their synthesis, glycans attached to glycoproteins have species-specific structures generated by the presence of different sets of enzymes and acceptor substrates in each organism. In this review, we present a comparative analysis of the main glycosylation pathways shared by humans and the fungal pathogen Candida albicans: N-linked glycosylation, O-linked mannosylation and glycosylphosphatidylinositol-anchorage. The knowledge of similarities and divergences between these metabolic pathways could help find new pharmacological targets for C. albicans infection.
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22
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Goddeeris MM, Wu B, Venzke D, Yoshida-Moriguchi T, Saito F, Matsumura K, Moore SA, Campbell KP. LARGE glycans on dystroglycan function as a tunable matrix scaffold to prevent dystrophy. Nature 2013; 503:136-40. [PMID: 24132234 DOI: 10.1038/nature12605] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 08/27/2013] [Indexed: 01/11/2023]
Abstract
The dense glycan coat that surrounds every cell is essential for cellular development and physiological function, and it is becoming appreciated that its composition is highly dynamic. Post-translational addition of the polysaccharide repeating unit [-3-xylose-α1,3-glucuronic acid-β1-]n by like-acetylglucosaminyltransferase (LARGE) is required for the glycoprotein dystroglycan to function as a receptor for proteins in the extracellular matrix. Reductions in the amount of [-3-xylose-α1,3-glucuronic acid-β1-]n (hereafter referred to as LARGE-glycan) on dystroglycan result in heterogeneous forms of muscular dystrophy. However, neither patient nor mouse studies has revealed a clear correlation between glycosylation status and phenotype. This disparity can be attributed to our lack of knowledge of the cellular function of the LARGE-glycan repeat. Here we show that coordinated upregulation of Large and dystroglycan in differentiating mouse muscle facilitates rapid extension of LARGE-glycan repeat chains. Using synthesized LARGE-glycan repeats we show a direct correlation between LARGE-glycan extension and its binding capacity for extracellular matrix ligands. Blocking Large upregulation during muscle regeneration results in the synthesis of dystroglycan with minimal LARGE-glycan repeats in association with a less compact basement membrane, immature neuromuscular junctions and dysfunctional muscle predisposed to dystrophy. This was consistent with the finding that patients with increased clinical severity of disease have fewer LARGE-glycan repeats. Our results reveal that the LARGE-glycan of dystroglycan serves as a tunable extracellular matrix protein scaffold, the extension of which is required for normal skeletal muscle function.
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Affiliation(s)
- Matthew M Goddeeris
- 1] Howard Hughes Medical Institute, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA [2] Department of Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa 52242, USA
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23
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Sharpe KM, Premsukh MD, Townsend D. Alterations of dystrophin-associated glycoproteins in the heart lacking dystrophin or dystrophin and utrophin. J Muscle Res Cell Motil 2013; 34:395-405. [PMID: 24096570 DOI: 10.1007/s10974-013-9362-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/26/2013] [Indexed: 11/26/2022]
Abstract
Heart disease is a leading cause of death in patients with Duchenne muscular dystrophy (DMD). Patients with DMD lack the protein dystrophin, which is widely expressed in striated muscle. In skeletal muscle, the loss of dystrophin results in dramatically decreased expression of the dystrophin associated glycoprotein complex (DGC). Interestingly, in the heart the DGC is normally expressed without dystrophin; this has been attributed to presence of the dystrophin homologue utrophin. We demonstrate here that neither utrophin nor dystrophin are required for the expression of the cardiac DGC. However, alpha-dystroglycan (α-DG), a major component of the DGC, is differentially glycosylated in dystrophin-(mdx) and dystrophin-/utrophin-(dko) deficient mouse hearts. In both models the altered α-DG retains laminin binding activity, but has an altered localization at the sarcolemma. In hearts lacking both dystrophin and utrophin, the alterations in α-DG glycosylation are even more dramatic with changes in gel migration equivalent to 24 ± 3 kDa. These data show that the absence of dystrophin and utrophin alters the processing of α-DG; however it is not clear if these alterations are a consequence of the loss of a direct interaction with dystrophin/utrophin or results from an indirect response to the presence of severe pathology. Recently there have been great advances in our understanding of the glycosylation of α-DG regarding its role as a laminin receptor. Here we present data that alterations in glycosylation occur in the hearts of animal models of DMD, but these changes do not affect laminin binding. The physiological consequences of these alterations remain unknown, but may have significant implications for the development of therapies for DMD.
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Affiliation(s)
- Katharine M Sharpe
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, MN, 55455, USA
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24
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Martinez HR, Craigen WJ, Ummat M, Adesina AM, Lotze TE, Jefferies JL. Novel cardiovascular findings in association with a POMT2 mutation: three siblings with α-dystroglycanopathy. Eur J Hum Genet 2013; 22:486-91. [PMID: 24002165 DOI: 10.1038/ejhg.2013.165] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 06/20/2013] [Accepted: 06/26/2013] [Indexed: 11/09/2022] Open
Abstract
Dystroglycanopathies are a genetically heterogeneous subset of congenital muscular dystrophies that exhibit autosomal recessive inheritance and are characterized by abnormal glycosylation of α-dystroglycan. In particular, POMT2 (protein O-mannosyltransferase-2) mutations have been identified in congenital muscular dystrophy patients with a wide range of clinical involvement, ranging from the severe muscle-eye-brain disease and Walker-Warburg syndrome to limb girdle muscular dystrophy without structural brain or ocular involvement. Cardiovascular disease is thought to be uncommon in congenital muscular dystrophy, with rare reports of cardiac involvement. We describe three brothers aged 21, 19, and 17 years with an apparently homozygous POMT2 mutation who all presented with congenital muscular dystrophy, intellectual disabilities, and distinct cardiac abnormalities. All three brothers were homozygous for a p.Tyr666Cys missense mutation in exon 19 of the POMT2 gene. On screening echocardiograms, all siblings demonstrated significant dilatation of the aortic root and depressed left ventricular systolic function and/or left ventricular wall motion abnormalities. Our report is the first to document an association between POMT2 mutations and aortopathy with concomitant depressed left ventricular systolic function. On the basis of our findings, we suggest patients with POMT2 gene mutations be screened not only for myocardial dysfunction but also for aortopathy. In addition, given the potential for progression of myocardial dysfunction and/or aortic dilatation, longitudinal surveillance imaging is recommended both for patients with disease as well as those that have normal baseline imaging.
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Affiliation(s)
- Hugo R Martinez
- Section of Pediatrics, University of Texas Medical Branch, Houston, TX, USA
| | - William J Craigen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Monika Ummat
- Section of Pediatric Neurology, Texas Children's Hospital, Houston, TX, USA
| | | | - Timothy E Lotze
- Section of Pediatric Neurology, Texas Children's Hospital, Houston, TX, USA
| | - John L Jefferies
- Heart Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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25
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Functional and molecular characterization of novel Hansenula polymorpha genes, HpPMT5 and HpPMT6, encoding protein O-mannosyltransferases. Fungal Genet Biol 2013; 58-59:10-24. [DOI: 10.1016/j.fgb.2013.08.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 07/20/2013] [Accepted: 08/01/2013] [Indexed: 02/02/2023]
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26
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González M, Brito N, Frías M, González C. Botrytis cinerea protein O-mannosyltransferases play critical roles in morphogenesis, growth, and virulence. PLoS One 2013; 8:e65924. [PMID: 23762450 PMCID: PMC3675079 DOI: 10.1371/journal.pone.0065924] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 04/30/2013] [Indexed: 12/22/2022] Open
Abstract
Protein O-glycosylation is crucial in determining the structure and function of numerous secreted and membrane-bound proteins. In fungi, this process begins with the addition of a mannose residue by protein O-mannosyltransferases (PMTs) in the lumen side of the ER membrane. We have generated mutants of the three Botrytis cinerea pmt genes to study their role in the virulence of this wide-range plant pathogen. B. cinerea PMTs, especially PMT2, are critical for the stability of the cell wall and are necessary for sporulation and for the generation of the extracellular matrix. PMTs are also individually required for full virulence in a variety of hosts, with a special role in the penetration of intact plant leaves. The most significant case is that of grapevine leaves, whose penetration requires the three functional PMTs. Furthermore, PMT2 also contributes significantly to fungal adherence on grapevine and tobacco leaves. Analysis of extracellular and membrane proteins showed significant changes in the pattern of protein secretion and glycosylation by the pmt mutants, and allowed the identification of new protein substrates putatively glycosylated by specific PMTs. Since plants do no possess these enzymes, PMTs constitute a promising target in the development of novel control strategies against B. cinerea.
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Affiliation(s)
- Mario González
- Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, La Laguna (Tenerife), Spain
| | - Nélida Brito
- Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, La Laguna (Tenerife), Spain
| | - Marcos Frías
- Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, La Laguna (Tenerife), Spain
| | - Celedonio González
- Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, La Laguna (Tenerife), Spain
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27
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Marshall JL, Kwok Y, McMorran BJ, Baum LG, Crosbie-Watson RH. The potential of sarcospan in adhesion complex replacement therapeutics for the treatment of muscular dystrophy. FEBS J 2013; 280:4210-29. [PMID: 23601082 DOI: 10.1111/febs.12295] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 04/12/2013] [Indexed: 12/23/2022]
Abstract
Three adhesion complexes span the sarcolemma and facilitate critical connections between the extracellular matrix and the actin cytoskeleton: the dystrophin- and utrophin-glycoprotein complexes and α7β1 integrin. Loss of individual protein components results in a loss of the entire protein complex and muscular dystrophy. Muscular dystrophy is a progressive, lethal wasting disease characterized by repetitive cycles of myofiber degeneration and regeneration. Protein-replacement therapy offers a promising approach for the treatment of muscular dystrophy. Recently, we demonstrated that sarcospan facilitates protein-protein interactions amongst the adhesion complexes and is an important potential therapeutic target. Here, we review current protein-replacement strategies, discuss the potential benefits of sarcospan expression, and identify important experiments that must be addressed for sarcospan to move to the clinic.
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Affiliation(s)
- Jamie L Marshall
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA
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28
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Loibl M, Strahl S. Protein O-mannosylation: what we have learned from baker's yeast. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2438-46. [PMID: 23434682 DOI: 10.1016/j.bbamcr.2013.02.008] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 02/05/2013] [Accepted: 02/10/2013] [Indexed: 01/06/2023]
Abstract
BACKGROUND Protein O-mannosylation is a vital type of glycosylation that is conserved among fungi, animals, and humans. It is initiated in the endoplasmic reticulum (ER) where the synthesis of the mannosyl donor substrate and the mannosyltransfer to proteins take place. O-mannosylation defects interfere with cell wall integrity and ER homeostasis in yeast, and define a pathomechanism of severe neuromuscular diseases in humans. SCOPE OF REVIEW On the molecular level, the O-mannosylation pathway and the function of O-mannosyl glycans have been characterized best in the eukaryotic model yeast Saccharomyces cerevisiae. In this review we summarize general features of protein O-mannosylation, including biosynthesis of the mannosyl donor, characteristics of acceptor substrates, and the protein O-mannosyltransferase machinery in the yeast ER. Further, we discuss the role of O-mannosyl glycans and address the question why protein O-mannosylation is essential for viability of yeast cells. GENERAL SIGNIFICANCE Understanding of the molecular mechanisms of protein O-mannosylation in yeast could lead to the development of novel antifungal drugs. In addition, transfer of the knowledge from yeast to mammals could help to develop diagnostic and therapeutic approaches in the frame of neuromuscular diseases. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
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29
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Dobson CM, Hempel SJ, Stalnaker SH, Stuart R, Wells L. O-Mannosylation and human disease. Cell Mol Life Sci 2012; 70:2849-57. [PMID: 23115008 DOI: 10.1007/s00018-012-1193-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 10/02/2012] [Accepted: 10/08/2012] [Indexed: 12/21/2022]
Abstract
Glycosylation of proteins is arguably the most prevalent co- and post-translational modification. It is responsible for increased heterogeneity and functional diversity of proteins. Here we discuss the importance of one type of glycosylation, specifically O-mannosylation and its relationship to a number of human diseases. The most widely studied O-mannose modified protein is alpha-dystroglycan (α-DG). Recent studies have focused intensely on α-DG due to the severity of diseases associated with its improper glycosylation. O-mannosylation of α-DG is involved in cancer metastasis, arenavirus entry, and multiple forms of congenital muscular dystrophy [1, 2]. In this review, we discuss the structural and functional characteristics of O-mannose-initiated glycan structures on α-DG, enzymes involved in the O-mannosylation pathway, and the diseases that are a direct result of disruptions within this pathway.
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Affiliation(s)
- Christina M Dobson
- Department of Biochemistry and Molecular Biology, Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
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30
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Tanner W, Lehle L. More than 40 years of glycobiology in Regensburg. Biochem Biophys Res Commun 2012; 425:578-582. [PMID: 22925677 DOI: 10.1016/j.bbrc.2012.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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31
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Beedle AM, Turner AJ, Saito Y, Lueck JD, Foltz SJ, Fortunato MJ, Nienaber PM, Campbell KP. Mouse fukutin deletion impairs dystroglycan processing and recapitulates muscular dystrophy. J Clin Invest 2012; 122:3330-42. [PMID: 22922256 DOI: 10.1172/jci63004] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 06/21/2012] [Indexed: 11/17/2022] Open
Abstract
Dystroglycan is a transmembrane glycoprotein that links the extracellular basement membrane to cytoplasmic dystrophin. Disruption of the extensive carbohydrate structure normally present on α-dystroglycan causes an array of congenital and limb girdle muscular dystrophies known as dystroglycanopathies. The essential role of dystroglycan in development has hampered elucidation of the mechanisms underlying dystroglycanopathies. Here, we developed a dystroglycanopathy mouse model using inducible or muscle-specific promoters to conditionally disrupt fukutin (Fktn), a gene required for dystroglycan processing. In conditional Fktn-KO mice, we observed a near absence of functionally glycosylated dystroglycan within 18 days of gene deletion. Twenty-week-old KO mice showed clear dystrophic histopathology and a defect in glycosylation near the dystroglycan O-mannose phosphate, whether onset of Fktn excision driven by muscle-specific promoters occurred at E8 or E17. However, the earlier gene deletion resulted in more severe phenotypes, with a faster onset of damage and weakness, reduced weight and viability, and regenerating fibers of smaller size. The dependence of phenotype severity on the developmental timing of muscle Fktn deletion supports a role for dystroglycan in muscle development or differentiation. Moreover, given that this conditional Fktn-KO mouse allows the generation of tissue- and timing-specific defects in dystroglycan glycosylation, avoids embryonic lethality, and produces a phenotype resembling patient pathology, it is a promising new model for the study of secondary dystroglycanopathy.
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Affiliation(s)
- Aaron M Beedle
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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32
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Matsuzawa T, Ohashi T, Nakase M, Yoritsune KI, Takegawa K. Galactose-Specific Recognition System in the Fission Yeast Schizosaccharomyces pombe. TRENDS GLYCOSCI GLYC 2012. [DOI: 10.4052/tigg.24.24] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Tomohiko Matsuzawa
- Department of Bioscience & Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan
| | - Takao Ohashi
- Department of Bioscience & Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan
| | - Mai Nakase
- Department of Bioscience & Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan
| | - Ken-ichi Yoritsune
- Department of Bioscience & Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan
| | - Kaoru Takegawa
- Department of Bioscience & Biotechnology, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan
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Protein Glycosylation in Aspergillus fumigatus Is Essential for Cell Wall Synthesis and Serves as a Promising Model of Multicellular Eukaryotic Development. Int J Microbiol 2011; 2012:654251. [PMID: 21977037 PMCID: PMC3184424 DOI: 10.1155/2012/654251] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 07/19/2011] [Indexed: 02/05/2023] Open
Abstract
Glycosylation is a conserved posttranslational modification that is found in all eukaryotes, which helps generate proteins with multiple functions. Our knowledge of glycosylation mainly comes from the investigation of the yeast Saccharomyces cerevisiae and mammalian cells. However, during the last decade, glycosylation in the human pathogenic mold Aspergillus fumigatus has drawn significant attention. It has been revealed that glycosylation in A. fumigatus is crucial for its growth, cell wall synthesis, and development and that the process is more complicated than that found in the budding yeast S. cerevisiae. The present paper implies that the investigation of glycosylation in A. fumigatus is not only vital for elucidating the mechanism of fungal cell wall synthesis, which will benefit the design of new antifungal therapies, but also helps to understand the role of protein glycosylation in the development of multicellular eukaryotes. This paper describes the advances in functional analysis of protein glycosylation in A. fumigatus.
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Lommel M, Schott A, Jank T, Hofmann V, Strahl S. A conserved acidic motif is crucial for enzymatic activity of protein O-mannosyltransferases. J Biol Chem 2011; 286:39768-75. [PMID: 21956107 DOI: 10.1074/jbc.m111.281196] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein O-mannosylation is an essential modification in fungi and mammals. It is initiated at the endoplasmic reticulum by a conserved family of dolichyl phosphate mannose-dependent protein O-mannosyltransferases (PMTs). PMTs are integral membrane proteins with two hydrophilic loops (loops 1 and 5) facing the endoplasmic reticulum lumen. Formation of dimeric PMT complexes is crucial for mannosyltransferase activity, but the direct cause is not known to date. In bakers' yeast, O-mannosylation is catalyzed largely by heterodimeric Pmt1p-Pmt2p and homodimeric Pmt4p complexes. To further characterize Pmt1p-Pmt2p complexes, we developed a photoaffinity probe based on the artificial mannosyl acceptor substrate Tyr-Ala-Thr-Ala-Val. The photoreactive probe was preferentially cross-linked to Pmt1p, and deletion of the loop 1 (but not loop 5) region abolished this interaction. Analysis of Pmt1p loop 1 mutants revealed that especially Glu-78 is crucial for binding of the photoreactive probe. Glu-78 belongs to an Asp-Glu motif that is highly conserved among PMTs. We further demonstrate that single amino acid substitutions in this motif completely abolish activity of Pmt4p complexes. In contrast, both acidic residues need to be exchanged to eliminate activity of Pmt1p-Pmt2p complexes. On the basis of our data, we propose that the loop 1 regions of dimeric complexes form part of the catalytic site.
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Affiliation(s)
- Mark Lommel
- Centre for Organismal Studies Heidelberg, University of Heidelberg, D-69120 Heidelberg, Germany
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35
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Stalnaker SH, Stuart R, Wells L. Mammalian O-mannosylation: unsolved questions of structure/function. Curr Opin Struct Biol 2011; 21:603-9. [PMID: 21945038 DOI: 10.1016/j.sbi.2011.09.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 08/31/2011] [Accepted: 09/01/2011] [Indexed: 11/29/2022]
Abstract
Post-translational modification of polypeptides with glycans increases the diversity of the structures of proteins and imparts increased functional diversity. Here, we review the current literature on a relatively new O-glycosylation pathway, the mammalian O-mannosylation pathway. The importance of O-mannosylation is illustrated by the fact that O-mannose glycan structures play roles in a variety of processes including viral entry into cells, metastasis, cell adhesion, and neuronal development. Furthermore, mutations in the enzymes of this pathway are causal for a variety of congenital muscular dystrophies. Here we highlight the protein substrates, glycan structures, and enzymes involved in O-mannosylation as well as our gaps in understanding structure/function relationships in this biosynthetic pathway.
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Affiliation(s)
- Stephanie H Stalnaker
- University of Georgia, Complex Carbohydrate Research Center, Athens, GA, United States
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36
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Godfrey C, Clement E, Abbs S, Muntoni F. Exclusion of WWP1
mutations in a cohort of dystroglycanopathy patients. Muscle Nerve 2011; 44:388-92. [DOI: 10.1002/mus.22068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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37
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Hu H, Li J, Gagen CS, Gray NW, Zhang Z, Qi Y, Zhang P. Conditional knockout of protein O-mannosyltransferase 2 reveals tissue-specific roles of O-mannosyl glycosylation in brain development. J Comp Neurol 2011; 519:1320-37. [PMID: 21452199 DOI: 10.1002/cne.22572] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The meninges produce essential signaling molecules and major protein components of the pial basement membrane during normal brain development. Disruptions in the pial basement membrane underlie neural ectopia seen in those congenital muscular dystrophies (CMDs) caused by mutations in genes involved in O-mannosyl glycosylation. In mammals, biosynthesis of O-mannosyl glycans is initiated by a complex of mutually indispensable protein O-mannosyltransferases 1 and 2 (POMT1 and 2). To study the roles of O-mannosylation in brain development we generated a conditional allele of POMT2. POMT2 nulllizygosity resulted in embryonic lethality because of a defective Reichert's membrane. Brain-specific deletion of POMT2 resulted in hypoglycosylation of α-dystroglycan (DG) and abolished laminin binding activity. The effect of POMT2 deletion on brain development was dependent on timing, as earlier deletion resulted in more severe phenotypes. Multiple brain malformations including overmigration of neocortical neurons and migration failure of granule cells in the cerebellum were observed. Immunofluorescence staining and transmission electron microscopy revealed that these migration defects were closely associated with disruptions in the pial basement membrane. Interestingly, POMT2 deletion in the meninges (and blood vessels) did not disrupt the development of the neocortex. Thus, normal brain development requires protein O-mannosylation activity in neural tissue but not the meninges. These results suggest that gene therapy should be directed to the neural tissue instead of the meninges.
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Affiliation(s)
- Huaiyu Hu
- Department of Neuroscience and Physiology, Upstate Medical University, Syracuse, New York 13210, USA.
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38
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Avsar-Ban E, Ishikawa H, Manya H, Watanabe M, Akiyama S, Miyake H, Endo T, Tamaru Y. Protein O-mannosylation is necessary for normal embryonic development in zebrafish. Glycobiology 2010; 20:1089-102. [PMID: 20466645 DOI: 10.1093/glycob/cwq069] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Two distinct cDNAs corresponding to two zebrafish protein O-mannosyltransferase genes, zPOMT1 and zPOMT2, were cloned from early developmental embryos. Gene expression analysis revealed that zPOMT1 and zPOMT2 were expressed in similar patterns during early embryonic development and in all adult tissues. To study the regulation of zPOMT1 and zPOMT2 mRNA distribution during zebrafish embryogenesis, we injected enhanced green fluorescent protein (EGFP) mRNA fused to the 3'untranslated regions of each zPOMT gene. The distribution of EGFP resulting from the two constructs was similar. Injection of antisense morpholino oligonucleotides of zPOMT1 and zPOMT2 resulted in several severe phenotypes-including bended body, edematous pericaridium and abnormal eye pigmentation. Immunohistochemistry using anti-glycosylated alpha-dystroglycan antibody (IIH6) and morphological analysis revealed that the phenotypes of zPOMT2 knockdown were more severe than those of zPOMT1 knockdown, even though the IIH6 reactivity was lost in both zPOMT1 and zPOMT2 morphants. Finally, only when both zPOMT1 and zPOMT2 were expressed in human embryonic kidney 293T cells were high levels of protein O-mannosyltransferase activity detected, indicating that both zPOMT1 and zPOMT2 were required for full enzymatic activity. Moreover, either heterologous combination, zPOMT1 and human POMT2 (hPOMT2) or hPOMT1 and zPOMT2, resulted in enzymatic activity in cultured cells. These results indicate that the protein O-mannosyltransferase machinery in zebrafish and humans is conserved and suggest that zebrafish may be useful for functional studies of protein O-mannosylation.
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Affiliation(s)
- Eriko Avsar-Ban
- Department of Life Science, Mie University Graduate School of Bioresources, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japan
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Mouyna I, Kniemeyer O, Jank T, Loussert C, Mellado E, Aimanianda V, Beauvais A, Wartenberg D, Sarfati J, Bayry J, Prévost MC, Brakhage AA, Strahl S, Huerre M, Latgé JP. Members of protein O-mannosyltransferase family in Aspergillus fumigatus differentially affect growth, morphogenesis and viability. Mol Microbiol 2010; 76:1205-21. [PMID: 20398215 DOI: 10.1111/j.1365-2958.2010.07164.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
O-mannosylation is an essential protein modification in eukaryotes. It is initiated at the endoplasmic reticulum by O-mannosyltransferases (PMT) that are evolutionary conserved from yeast to humans. The PMT family is phylogenetically classified into PMT1, PMT2 and PMT4 subfamilies, which differ in protein substrate specificity and number of genes per subfamily. In this study, we characterized for the first time the whole PMT family of a pathogenic filamentous fungus, Aspergillus fumigatus. Genome analysis showed that only one member of each subfamily is present in A. fumigatus, PMT1, PMT2 and PMT4. Despite the fact that all PMTs are transmembrane proteins with conserved peptide motifs, the phenotype of each PMT deletion mutant was very different in A. fumigatus. If disruption of PMT1 did not reveal any phenotype, deletion of PMT2 was lethal. Disruption of PMT4 resulted in abnormal mycelial growth and highly reduced conidiation associated to significant proteomic changes. The double pmt1pmt4 mutant was lethal. The single pmt4 mutant exhibited an exquisite sensitivity to echinocandins that is associated to major changes in the expression of signal transduction cascade genes. These results indicate that the PMT family members play a major role in growth, morphogenesis and viability of A. fumigatus.
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Affiliation(s)
- Isabelle Mouyna
- Unité des Aspergillus, Institut Pasteur, 25 rue du Docteur Roux 75724 Paris Cedex 15, France.
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Nakamura N, Lyalin D, Panin VM. Protein O-mannosylation in animal development and physiology: from human disorders to Drosophila phenotypes. Semin Cell Dev Biol 2010; 21:622-30. [PMID: 20362685 DOI: 10.1016/j.semcdb.2010.03.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 03/10/2010] [Accepted: 03/25/2010] [Indexed: 12/13/2022]
Abstract
Protein O-mannosylation has a profound effect on the development and physiology of mammalian organisms. Mutations in genes affecting O-mannosyl glycan biosynthesis result in congenital muscular dystrophies. The main pathological mechanism triggered by O-mannosylation defects is a compromised interaction of cells with the extracellular matrix due to abnormal glycosylation of alpha-dystroglycan. Hypoglycosylation of alpha-dystroglycan impairs its ligand-binding activity and results in muscle degeneration and failure of neuronal migration. Recent experiments revealed the existence of compensatory mechanisms that could ameliorate defects of O-mannosylation. However, these mechanisms remain poorly understood. O-mannosylation and dystroglycan pathway genes show remarkable evolutionary conservation in a wide range of metazoans. Mutations and downregulation of these genes in zebrafish and Drosophila result in muscle defects and degeneration, also causing neurological phenotypes, which suggests that O-mannosylation has similar functions in mammals and lower animals. Thus, future studies in genetically tractable model organisms, such as zebrafish and Drosophila, should help to reveal molecular and genetic mechanisms of mammalian O-mannosylation and its role in the regulation of dystroglycan function.
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Affiliation(s)
- Naosuke Nakamura
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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42
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Fang W, Ding W, Wang B, Zhou H, Ouyang H, Ming J, Jin C. Reduced expression of the O-mannosyltransferase 2 (AfPmt2) leads to deficient cell wall and abnormal polarity in Aspergillus fumigatus. Glycobiology 2010; 20:542-52. [PMID: 20053626 DOI: 10.1093/glycob/cwp206] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Protein O-mannosyltransferases (PMTs) initiate O-mannosylation of secretory proteins, which are of fundamental importance in eukaryotes. The human fungal pathogen Aspergillus fumigatus possesses three genes encoding for PMTs, namely, Afpmt1, Afpmt2 and Afpmt4. We have previously shown that lack of AfPmt1 leads to a temperature-sensitive phenotype featured with severe defects in hyphal growth, conidiation, cell wall integrity and morphology at elevated temperatures. In this study, a conditional mutant P2 was constructed by replacing the native promoter of the Afpmt2 with the Aspergillus nidulans alcA promoter. Reduced expression of the Afpmt2 gene led to a lagged germination, retarded hyphal growth, reduced conidiation and defect in cell wall integrity; however, no temperature-sensitive growth was observed. Further analysis revealed that reduced expression of the Afpmt2 caused a failure of the actin re-arrangement. Our results suggest that Afpmt2 gene was required for growth and played a role distinct from that of the Afpmt1 in A. fumigatus.
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Affiliation(s)
- Wenxia Fang
- Key Laboratory of Systematic Mycology and Lichenology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
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44
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Hewitt JE. Abnormal glycosylation of dystroglycan in human genetic disease. Biochim Biophys Acta Mol Basis Dis 2009; 1792:853-61. [DOI: 10.1016/j.bbadis.2009.06.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 06/05/2009] [Accepted: 06/10/2009] [Indexed: 10/20/2022]
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45
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Willger SD, Ernst JF, Alspaugh JA, Lengeler KB. Characterization of the PMT gene family in Cryptococcus neoformans. PLoS One 2009; 4:e6321. [PMID: 19633715 PMCID: PMC2711527 DOI: 10.1371/journal.pone.0006321] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 06/23/2009] [Indexed: 12/15/2022] Open
Abstract
Background Protein-O-mannosyltransferases (Pmt's) catalyze the initial step of protein-O-glycosylation, the addition of mannose residues to serine or threonine residues of target proteins. Methodology/Principal Findings Based on protein similarities, this highly conserved protein family can be divided into three subfamilies: the Pmt1 sub-family, the Pmt2 sub-family and the Pmt4 sub-family. In contrast to Saccharomyces cerevisiae and Candida albicans, but similar to filamentous fungi, three putative PMT genes (PMT1, PMT2, and PMT4) were identified in the genome of the human fungal pathogen Cryptococcus neoformans. Similar to Schizosaccharomyces pombe and C. albicans, C. neoformans PMT2 is an essential gene. In contrast, the pmt1 and pmt4 single mutants are viable; however, the pmt1/pmt4 deletions are synthetically lethal. Mutation of PMT1 and PMT4 resulted in distinct defects in cell morphology and cell integrity. The pmt1 mutant was more susceptible to SDS medium than wild-type strains and the mutant cells were enlarged. The pmt4 mutant grew poorly on high salt medium and demonstrated abnormal septum formation and defects in cell separation. Interestingly, the pmt1 and pmt4 mutants demonstrated variety-specific differences in the levels of susceptibility to osmotic and cell wall stress. Delayed melanin production in the pmt4 mutant was the only alteration of classical virulence-associated phenotypes. However, the pmt1 and pmt4 mutants showed attenuated virulence in a murine inhalation model of cryptococcosis. Conclusion/Significance These findings suggest that C. neoformans protein-O-mannosyltransferases play a crucial role in maintaining cell morphology, and that reduced protein-O-glycosylation leads to alterations in stress resistance, cell wall composition, cell integrity, and survival within the host.
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Affiliation(s)
- Sven D Willger
- Institut für Mikrobiologie, Molekulare Mykologie, Heinrich-Heine-Universität, Düsseldorf, Germany.
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Production of heterologous proteins using the fission-yeast (Schizosaccharomyces pombe) expression system. Biotechnol Appl Biochem 2009; 53:227-35. [PMID: 19531030 DOI: 10.1042/ba20090048] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The fission yeast Schizosaccharomyces pombe is a particularly useful model for studying the function and regulation of genes from higher eukaryotes. The genome of Sc. pombe has been sequenced, and DNA microarray, proteome and transcriptome analyses have been carried out. Among the well-characterized yeast species, Sc. pombe is considered an attractive host for the production of heterologous proteins. Expression vectors for high-level expression in Sc. pombe have been developed and many foreign proteins have been successfully expressed. However, further improvements in the protein-expressing host systems are still required for the production of heterologous proteins involved in post-translational modification, metabolism and intracellular trafficking. This minireview focuses on recent advances in heterologous protein production by use of engineered fission-yeast strains.
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47
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Abstract
Protein O-mannosylation is an essential modification in fungi and animals. Different from most other types of O-glycosylation, protein O-mannosylation is initiated in the endoplasmic reticulum by the transfer of mannose from dolichol monophosphate-activated mannose to serine and threonine residues of secretory proteins. In recent years, it has emerged that even bacteria are capable of O-mannosylation and that the biosynthetic pathway of O-mannosyl glycans is conserved between pro- and eukaryotes. In this review, we summarize the observations that have opened up the field and highlight characteristics of O-mannosylation in the different domains/kingdoms of life.
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Affiliation(s)
- Mark Lommel
- Department V Cell Chemistry, Heidelberg Institute for Plant Sciences, University of Heidelberg, Heidelberg, Germany
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48
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Ikeda Y, Ohashi T, Tanaka N, Takegawa K. Identification and characterization of a gene required for α1,2-mannose extension in theO-linked glycan synthesis pathway inSchizosaccharomyces pombe. FEMS Yeast Res 2009; 9:115-25. [DOI: 10.1111/j.1567-1364.2008.00458.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Murakami-Sekimata A, Sato K, Sato K, Takashima A, Nakano A. O-Mannosylation is required for the solubilization of heterologously expressed human β-amyloid precursor protein inSaccharomyces cerevisiae. Genes Cells 2009; 14:205-15. [DOI: 10.1111/j.1365-2443.2008.01263.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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50
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Maeda Y, Kinoshita T. Dolichol-phosphate mannose synthase: Structure, function and regulation. Biochim Biophys Acta Gen Subj 2008; 1780:861-8. [DOI: 10.1016/j.bbagen.2008.03.005] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Revised: 02/11/2008] [Accepted: 03/06/2008] [Indexed: 11/30/2022]
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