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Whole exome sequencing identified a novel homozygous ARV1 mutation in an Iranian family with developmental and epileptic encephalopathy-38. Meta Gene 2021. [DOI: 10.1016/j.mgene.2021.100953] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Gutiérrez-García L, Arró M, Altabella T, Ferrer A, Boronat A. Structural and functional analysis of tomato sterol C22 desaturase. BMC PLANT BIOLOGY 2021; 21:141. [PMID: 33731007 PMCID: PMC7972189 DOI: 10.1186/s12870-021-02898-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/21/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Sterols are structural and functional components of eukaryotic cell membranes. Plants produce a complex mixture of sterols, among which β-sitosterol, stigmasterol, campesterol, and cholesterol in some Solanaceae, are the most abundant species. Many reports have shown that the stigmasterol to β-sitosterol ratio changes during plant development and in response to stresses, suggesting that it may play a role in the regulation of these processes. In tomato (Solanum lycopersicum), changes in the stigmasterol to β-sitosterol ratio correlate with the induction of the only gene encoding sterol C22-desaturase (C22DES), the enzyme specifically involved in the conversion of β-sitosterol to stigmasterol. However, despite the biological interest of this enzyme, there is still a lack of knowledge about several relevant aspects related to its structure and function. RESULTS In this study we report the subcellular localization of tomato C22DES in the endoplasmic reticulum (ER) based on confocal fluorescence microscopy and cell fractionation analyses. Modeling studies have also revealed that C22DES consists of two well-differentiated domains: a single N-terminal transmembrane-helix domain (TMH) anchored in the ER-membrane and a globular (or catalytic) domain that is oriented towards the cytosol. Although TMH is sufficient for the targeting and retention of the enzyme in the ER, the globular domain may also interact and be retained in the ER in the absence of the N-terminal transmembrane domain. The observation that a truncated version of C22DES lacking the TMH is enzymatically inactive revealed that the N-terminal membrane domain is essential for enzyme activity. The in silico analysis of the TMH region of plant C22DES revealed several structural features that could be involved in substrate recognition and binding. CONCLUSIONS Overall, this study contributes to expand the current knowledge on the structure and function of plant C22DES and to unveil novel aspects related to plant sterol metabolism.
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Affiliation(s)
- Laura Gutiérrez-García
- Center for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Barcelona, Spain
| | - Montserrat Arró
- Center for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Barcelona, Spain
- Department of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, University of Barcelona, 08028, Barcelona, Spain
| | - Teresa Altabella
- Center for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Barcelona, Spain
- Department of Biology, Healthcare and the Environment, Faculty of Pharmacy and Food Sciences, University of Barcelona, 08028, Barcelona, Spain
| | - Albert Ferrer
- Center for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Barcelona, Spain
- Department of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, University of Barcelona, 08028, Barcelona, Spain
| | - Albert Boronat
- Center for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Barcelona, Spain.
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, 08028, Barcelona, Spain.
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Wickramatunga PGTS, Gunawardene YINS, Wijesinghe KJ, Ellepola ANB, Dassanayake RS. RNAi-mediated silencing of ARV1 in Setaria digitata impairs in-vitro microfilariae release, embryogenesis and adult parasite viability. Vet Parasitol 2020; 284:109189. [PMID: 32739751 DOI: 10.1016/j.vetpar.2020.109189] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 07/15/2020] [Accepted: 07/16/2020] [Indexed: 02/01/2023]
Abstract
Setaria digitata is a nematode that resides in the peritoneal cavity of ruminants causing cerebrospinal nematodiasis disease affecting livestock and inflicting significant economic forfeitures in Asia. Further, this nematode can infect humans, causing abscesses, allergic reactions, enlarged lymph nodes, eye lesions and inflammation of the lungs. The 'ARE2 required for viability1' (ARV1) encodes for putative lipid transporter localized in the endoplasmic reticulum (ER) and Golgi complex membrane in humans and yeast. In the present study, the functional role of S. digitata ARV1 (SD-ARV1) was investigated using RNA interference (RNAi) reverse genetic tool. The targeted silencing SD-ARV1 transcripts by siRNA mediated RNAi resulted in a dramatic reduction of SD-ARV1 gene and protein expressions in S. digitata, which in turn modulated the parasitic motility, its production of eggs and microfilaria viability. Further, the same silencing caused severe phenotypic deformities such as distortion of eggs and embryonic development arrest in the intrauterine stages of adult female S. digitata. These results suggest that SD-ARV1 plays a pivotal role in worm embryogenesis, adult parasite motility and microfilariae viability. Finally, the ubiquitous presence of ARV1 in human filarial nematodes, its crucial functional roles in nematode biology and its remarkable diversity in primary protein structure compared to homologues in their hosts warrants further investigations to ascertain its candidacy in anthelmintic drug development.
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Affiliation(s)
| | | | - Kaveesha Jayani Wijesinghe
- Department of Chemistry, Faculty of Science, University of Colombo, PO 1490, Kumaratunga Munidasa Mawatha, Colombo, 00300, Sri Lanka
| | - Arjuna N B Ellepola
- Division of Oral Microbiology, Faculty of Dentistry, Health Sciences Center, Kuwait University, Kuwait
| | - Ranil Samantha Dassanayake
- Department of Chemistry, Faculty of Science, University of Colombo, PO 1490, Kumaratunga Munidasa Mawatha, Colombo, 00300, Sri Lanka.
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An Erg11 lanosterol 14-α-demethylase-Arv1 complex is required for Candida albicans virulence. PLoS One 2020; 15:e0235746. [PMID: 32678853 PMCID: PMC7367482 DOI: 10.1371/journal.pone.0235746] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 06/23/2020] [Indexed: 02/07/2023] Open
Abstract
Azole resistant fungal infections remain a health problem for the immune compromised. Current therapies are limited due to rises in new resistance mechanisms. Therefore, it is important to identify new drug targets for drug discovery and novel therapeutics. Arv1 (are1 are2required for viability 1) function is highly conserved between multiple pathogenic fungal species. Candida albicans (C. albicans) cells lacking CaArv1 are azole hypersusceptible and lack virulence. Saccharomyces cerevisiae (S. cerevisiae) Scarv1 cells are also azole hypersusceptible, a phenotype reversed by expression of CaArv1, indicating conservation in the molecular mechanism for azole susceptibility. To define the relationship between Arv1 function and azole susceptibility, we undertook a structure/function analysis of ScArv1. We identified several conserved amino acids within the ScArv1 homology domain (ScAhd) required for maintaining normal azole susceptibility. Erg11 lanosterol 14-α-demethylase is the rate-limiting enzyme in sterol biosynthesis and is the direct target of azole antifungals, so we used our ScArv1 mutants in order to explore the relationship between ScArv1 and ScErg11. Specific ScArv1 mutants ectopically expressed from a low copy plasmid were unable to restore normal azole susceptibility to Scarv1 cells and had reduced Erg11 protein levels. Erg11 protein stability depended on its ability to form a heterodimeric complex with Arv1. Complex formation was required for maintaining normal azole susceptibility. Scarv1 cells expressing orthologous CaArv1 mutants also had reduced CaErg11 levels, were unable to form a CaArv1-CaErg11 complex, and were azole hypersusceptible. Scarv1 cells expressing CaArv1 mutants unable to interact with CaErg11 could not sustain proper levels of the azole resistant CaErg11Y132F F145L protein. Caarv1/Caarv1 cells expressing CaArv1 mutants unable to interact with CaErg11 were found to lack virulence using a disseminated candidiasis mouse model. Expressing CaErg11Y132F F145L did not reverse the lack of virulence. We hypothesize that the role of Arv1 in Erg11-dependent azole resistance is to stabilize Erg11 protein level. Arv1 inhibition may represent an avenue for treating azole resistance.
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Davids M, Menezes M, Guo Y, McLean SD, Hakonarson H, Collins F, Worgan L, Billington CJ, Maric I, Littlejohn RO, Onyekweli T, Adams DR, Tifft CJ, Gahl WA, Wolfe LA, Christodoulou J, Malicdan MCV. Homozygous splice-variants in human ARV1 cause GPI-anchor synthesis deficiency. Mol Genet Metab 2020; 130:49-57. [PMID: 32165008 PMCID: PMC7303973 DOI: 10.1016/j.ymgme.2020.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/15/2020] [Accepted: 02/07/2020] [Indexed: 10/25/2022]
Abstract
BACKGROUND Mutations in the ARV1 Homolog, Fatty Acid Homeostasis Modulator (ARV1), have recently been described in association with early infantile epileptic encephalopathy 38. Affected individuals presented with epilepsy, ataxia, profound intellectual disability, visual impairment, and central hypotonia. In S. cerevisiae, Arv1 is thought to be involved in sphingolipid metabolism and glycophosphatidylinositol (GPI)-anchor synthesis. The function of ARV1 in human cells, however, has not been elucidated. METHODS Mutations were discovered through whole exome sequencing and alternate splicing was validated on the cDNA level. Expression of the variants was determined by qPCR and Western blot. Expression of GPI-anchored proteins on neutrophils and fibroblasts was analyzed by FACS and immunofluorescence microscopy, respectively. RESULTS Here we describe seven patients from two unrelated families with biallelic splice mutations in ARV1. The patients presented with early onset epilepsy, global developmental delays, profound hypotonia, delayed speech development, cortical visual impairment, and severe generalized cerebral and cerebellar atrophy. The splice variants resulted in decreased ARV1 expression and significant decreases in GPI-anchored protein on the membranes of neutrophils and fibroblasts, indicating that the loss of ARV1 results in impaired GPI-anchor synthesis. CONCLUSION Loss of GPI-anchored proteins on our patients' cells confirms that the yeast Arv1 function of GPI-anchor synthesis is conserved in humans. Overlap between the phenotypes in our patients and those reported for other GPI-anchor disorders suggests that ARV1-deficiency is a GPI-anchor synthesis disorder.
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Affiliation(s)
- Mariska Davids
- NIH Undiagnosed Diseases Program, Common Fund, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Minal Menezes
- Genetic Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Child and Adolescent Health and Genomic Medicine, Sydney Medical School, Sydney University, Sydney, NSW, Australia
| | - Yiran Guo
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Scott D McLean
- Department of Clinical Genetics, The Children's Hospital of San Antonio, San Antonio, TX, USA
| | - Hakon Hakonarson
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Felicity Collins
- Discipline of Child and Adolescent Health and Genomic Medicine, Sydney Medical School, Sydney University, Sydney, NSW, Australia; Department of Clinical Genetics, Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Lisa Worgan
- Department of Clinical Genetics, Liverpool Hospital, Liverpool, NSW, Australia
| | - Charles J Billington
- NIH Undiagnosed Diseases Program, Common Fund, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Irina Maric
- Hematology Service, Clinical Center, NIH, Bethesda, MD, USA
| | | | - Tito Onyekweli
- NIH Undiagnosed Diseases Program, Common Fund, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - David R Adams
- NIH Undiagnosed Diseases Program, Common Fund, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA; Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Cynthia J Tifft
- NIH Undiagnosed Diseases Program, Common Fund, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA; Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - William A Gahl
- NIH Undiagnosed Diseases Program, Common Fund, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA; Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA; Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Lynne A Wolfe
- NIH Undiagnosed Diseases Program, Common Fund, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA; Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - John Christodoulou
- Genetic Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Child and Adolescent Health and Genomic Medicine, Sydney Medical School, Sydney University, Sydney, NSW, Australia; Murdoch Children's Research Institute, Melbourne, VIC, Australia; Department of Pediatrics, Melbourne Medical School, University of Melbourne, Melbourne, VIC, Australia.
| | - May Christine V Malicdan
- NIH Undiagnosed Diseases Program, Common Fund, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA; Office of the Clinical Director, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA; Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.
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Lara JA, Burciaga-Monge A, Chávez A, Revés M, Lavilla R, Arró M, Boronat A, Altabella T, Ferrer A. Identification and Characterization of Sterol Acyltransferases Responsible for Steryl Ester Biosynthesis in Tomato. FRONTIERS IN PLANT SCIENCE 2018; 9:588. [PMID: 29868054 PMCID: PMC5952233 DOI: 10.3389/fpls.2018.00588] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 04/16/2018] [Indexed: 05/17/2023]
Abstract
Steryl esters (SEs) serve as a storage pool of sterols that helps to maintain proper levels of free sterols (FSs) in cell membranes throughout plant growth and development, and participates in the recycling of FSs and fatty acids released from cell membranes in aging tissues. SEs are synthesized by sterol acyltransferases, a family of enzymes that catalyze the transfer of fatty acil groups to the hydroxyl group at C-3 position of the sterol backbone. Sterol acyltransferases are categorized into acyl-CoA:sterol acyltransferases (ASAT) and phospholipid:sterol acyltransferases (PSAT) depending on whether the fatty acyl donor substrate is a long-chain acyl-CoA or a phospolipid. Until now, only Arabidopsis ASAT and PSAT enzymes (AtASAT1 and AtPSAT1) have been cloned and characterized in plants. Here we report the identification, cloning, and functional characterization of the tomato (Solanum lycopersicum cv. Micro-Tom) orthologs. SlPSAT1 and SlASAT1 were able to restore SE to wild type levels in the Arabidopsis psat1-2 and asat1-1 knock-out mutants, respectively. Expression of SlPSAT1 in the psat1-2 background also prevented the toxicity caused by an external supply of mevalonate and the early senescence phenotype observed in detached leaves of this mutant, whereas expression of SlASAT1 in the asat1-1 mutant revealed a clear substrate preference of the tomato enzyme for the sterol precursors cycloartenol and 24-methylene cycloartanol. Subcellular localization studies using fluorescently tagged SlPSAT1 and SlASAT1 proteins revealed that SlPSAT1 localize in cytoplasmic lipid droplets (LDs) while, in contrast to the endoplasmic reticulum (ER) localization of AtASAT1, SlASAT1 resides in the plasma membrane (PM). The possibility that PM-localized SlASAT1 may act catalytically in trans on their sterol substrates, which are presumably embedded in the ER membrane, is discussed. The widespread expression of SlPSAT1 and SlASAT1 genes in different tomato organs together with their moderate transcriptional response to several stresses suggests a dual role of SlPSAT1 and SlASAT1 in tomato plant and fruit development and the adaptive responses to stress. Overall, this study contributes to enlarge the current knowledge on plant sterol acyltransferases and set the basis for further studies aimed at understanding the role of SE metabolism in tomato plant growth and development.
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Affiliation(s)
- Juan A. Lara
- Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (CRAG) (CSIC-IRTA-UAB-UB), Campus Autonomous University of Barcelona, Cerdanyola del Vallès, Spain
- Present address: Juan A. Lara, School of Agritechnological Sciences (Extensión Cuauhtémoc), Autonomous University of Chihuahua, Chihuahua, Mexico
| | - Alma Burciaga-Monge
- Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (CRAG) (CSIC-IRTA-UAB-UB), Campus Autonomous University of Barcelona, Cerdanyola del Vallès, Spain
| | - Angel Chávez
- Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (CRAG) (CSIC-IRTA-UAB-UB), Campus Autonomous University of Barcelona, Cerdanyola del Vallès, Spain
| | - Marc Revés
- Laboratory of Medicinal Chemistry, Institute of Biomedicine University of Barcelona, Faculty of Pharmacy and Food Sciences, University of Barcelona, Barcelona, Spain
| | - Rodolfo Lavilla
- Laboratory of Medicinal Chemistry, Institute of Biomedicine University of Barcelona, Faculty of Pharmacy and Food Sciences, University of Barcelona, Barcelona, Spain
| | - Monserrat Arró
- Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (CRAG) (CSIC-IRTA-UAB-UB), Campus Autonomous University of Barcelona, Cerdanyola del Vallès, Spain
- Department of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, University of Barcelona, Barcelona, Spain
| | - Albert Boronat
- Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (CRAG) (CSIC-IRTA-UAB-UB), Campus Autonomous University of Barcelona, Cerdanyola del Vallès, Spain
- Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Teresa Altabella
- Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (CRAG) (CSIC-IRTA-UAB-UB), Campus Autonomous University of Barcelona, Cerdanyola del Vallès, Spain
- Department of Biology, Healthcare, and the Environment, Faculty of Pharmacy and Food Sciences, University of Barcelona, Barcelona, Spain
- *Correspondence: Teresa Altabella, Albert Ferrer,
| | - Albert Ferrer
- Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics (CRAG) (CSIC-IRTA-UAB-UB), Campus Autonomous University of Barcelona, Cerdanyola del Vallès, Spain
- Department of Biochemistry and Physiology, Faculty of Pharmacy and Food Sciences, University of Barcelona, Barcelona, Spain
- *Correspondence: Teresa Altabella, Albert Ferrer,
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Proper Sterol Distribution Is Required for Candida albicans Hyphal Formation and Virulence. G3-GENES GENOMES GENETICS 2016; 6:3455-3465. [PMID: 27587298 PMCID: PMC5100844 DOI: 10.1534/g3.116.033969] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Candida albicans is an opportunistic fungus responsible for the majority of systemic fungal infections. Multiple factors contribute to C. albicans pathogenicity. C. albicans strains lacking CaArv1 are avirulent. Arv1 has a conserved Arv1 homology domain (AHD) that has a zinc-binding domain containing two cysteine clusters. Here, we explored the role of the CaAHD and zinc-binding motif in CaArv1-dependent virulence. Overall, we found that the CaAHD was necessary but not sufficient for cells to be virulent, whereas the zinc-binding domain was essential, as Caarv1/Caarv1 cells expressing the full-length zinc-binding domain mutants, Caarv1C3S and Caarv1C28S, were avirulent. Phenotypically, we found a direct correlation between the avirulence of Caarv1/Caarv1, Caarrv1AHD, Caarv1C3S, and Caarv1C28S cells and defects in bud site selection, septa formation and localization, and hyphal formation and elongation. Importantly, all avirulent mutant strains lacked the ability to maintain proper sterol distribution. Overall, our results have established the importance of the AHD and zinc-binding domain in fungal invasion, and have correlated an avirulent phenotype with the inability to maintain proper sterol distribution.
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Palmer EE, Jarrett KE, Sachdev RK, Al Zahrani F, Hashem MO, Ibrahim N, Sampaio H, Kandula T, Macintosh R, Gupta R, Conlon DM, Billheimer JT, Rader DJ, Funato K, Walkey CJ, Lee CS, Loo C, Brammah S, Elakis G, Zhu Y, Buckley M, Kirk EP, Bye A, Alkuraya FS, Roscioli T, Lagor WR. Neuronal deficiency of ARV1 causes an autosomal recessive epileptic encephalopathy. Hum Mol Genet 2016; 25:3042-3054. [PMID: 27270415 DOI: 10.1093/hmg/ddw157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/29/2016] [Accepted: 05/18/2016] [Indexed: 12/21/2022] Open
Abstract
We report an individual who presented with severe neurodevelopmental delay and an intractable infantile-onset seizure disorder. Exome sequencing identified a homozygous single nucleotide change that abolishes a splice donor site in the ARV1 gene (c.294 + 1G > A homozygous). This variant completely prevented splicing in minigene assays, and resulted in exon skipping and an in-frame deletion of 40 amino acids in primary human fibroblasts (NP_073623.1: p.(Lys59_Asn98del). The p.(Lys59_Asn98del) and previously reported p.(Gly189Arg) ARV1 variants were evaluated for protein expression and function. The p.(Gly189Arg) variant partially rescued the temperature-dependent growth defect in arv1Δ yeast, while p.(Lys59-Asn98del) completely failed to rescue at restrictive temperature. In contrast to wild type human ARV1, neither variant expressed detectable levels of protein in mammalian cells. Mice with a neuronal deletion of Arv1 recapitulated the human phenotype, exhibiting seizures and a severe survival defect in adulthood. Our data support ARV1 deficiency as a cause of autosomal recessive epileptic encephalopathy.
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Affiliation(s)
- Elizabeth E Palmer
- Department of Women and Children's Health, Randwick Campus, University of New South Wales, NSW 2031, Australia.,Genetics of Learning Disability Service, Waratah, NSW 2298, Australia
| | - Kelsey E Jarrett
- Department of Molecular Physiology and Biophysics.,Integrative Molecular and Biomedical Sciences Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA
| | - Rani K Sachdev
- Department of Women and Children's Health, Randwick Campus, University of New South Wales, NSW 2031, Australia.,Sydney Children's Hospital, Randwick, NSW 2031, Australia
| | - Fatema Al Zahrani
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia
| | - Mais Omar Hashem
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia
| | - Niema Ibrahim
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia
| | - Hugo Sampaio
- Department of Women and Children's Health, Randwick Campus, University of New South Wales, NSW 2031, Australia.,Sydney Children's Hospital, Randwick, NSW 2031, Australia
| | - Tejaswi Kandula
- Department of Women and Children's Health, Randwick Campus, University of New South Wales, NSW 2031, Australia.,Sydney Children's Hospital, Randwick, NSW 2031, Australia
| | | | - Rajat Gupta
- Department of Molecular Physiology and Biophysics
| | - Donna M Conlon
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jeffrey T Billheimer
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Daniel J Rader
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kouichi Funato
- Department of Biofunctional Science and Technology, Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyam, Higashi-Hiroshima 739-8528, Japan
| | - Christopher J Walkey
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Christine Loo
- Department of Women and Children's Health, Randwick Campus, University of New South Wales, NSW 2031, Australia.,SEALS pathology, Randwick, NSW 2031, Australia
| | - Susan Brammah
- Electron Microscope Unit, Concord Repatriation General Hospital, Concord, NSW 2139, Australia
| | | | - Ying Zhu
- Genetics of Learning Disability Service, Waratah, NSW 2298, Australia.,SEALS pathology, Randwick, NSW 2031, Australia
| | | | - Edwin P Kirk
- Department of Women and Children's Health, Randwick Campus, University of New South Wales, NSW 2031, Australia.,Sydney Children's Hospital, Randwick, NSW 2031, Australia.,SEALS pathology, Randwick, NSW 2031, Australia
| | - Ann Bye
- Department of Women and Children's Health, Randwick Campus, University of New South Wales, NSW 2031, Australia.,Sydney Children's Hospital, Randwick, NSW 2031, Australia
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Saudi Arabia
| | - Tony Roscioli
- Sydney Children's Hospital, Randwick, NSW 2031, Australia.,Kinghorn Centre for Clinical Genomics, Garvan Institute, 370 Victoria St Darlinghurst, Sydney, Australia.,St Vincent's Clinical School, University of New South Wales, Sydney, Australia
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Ikeda A, Kajiwara K, Iwamoto K, Makino A, Kobayashi T, Mizuta K, Funato K. Complementation analysis reveals a potential role of human ARV1 in GPI anchor biosynthesis. Yeast 2015; 33:37-42. [PMID: 26460143 DOI: 10.1002/yea.3138] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 10/01/2015] [Accepted: 10/02/2015] [Indexed: 01/20/2023] Open
Abstract
ARV1 is involved in regulating lipid homeostasis but also in the biosynthesis of glycosylphosphatidylinositol (GPI) in Saccharomyces cerevisiae. Here, we examined whether human ARV1 can complement the role of yeast ARV1 in GPI biosynthesis. Overexpression of human ARV1 could rescue the phenotypes associated with GPI anchor synthesis defect in the yeast arv1Δ mutant. The results suggest that Arv1 function in GPI biosynthesis may be conserved in all eukaryotes, from yeast to humans.
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Affiliation(s)
- Atsuko Ikeda
- Department of Biofunctional Science and Technology, Graduate School of Biosphere Science, Hiroshima University, Japan
| | - Kentaro Kajiwara
- Department of Biofunctional Science and Technology, Graduate School of Biosphere Science, Hiroshima University, Japan
| | | | - Asami Makino
- Lipid Biology Laboratory and RIKEN, Saitama, Japan
| | | | - Keiko Mizuta
- Department of Biofunctional Science and Technology, Graduate School of Biosphere Science, Hiroshima University, Japan
| | - Kouichi Funato
- Department of Biofunctional Science and Technology, Graduate School of Biosphere Science, Hiroshima University, Japan
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10
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Lagor WR, Tong F, Jarrett KE, Lin W, Conlon DM, Smith M, Wang MY, Yenilmez BO, McCoy MG, Fields DW, O'Neill SM, Gupta R, Kumaravel A, Redon V, Ahima RS, Sturley SL, Billheimer JT, Rader DJ. Deletion of murine Arv1 results in a lean phenotype with increased energy expenditure. Nutr Diabetes 2015; 5:e181. [PMID: 26479315 PMCID: PMC4631934 DOI: 10.1038/nutd.2015.32] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Accepted: 06/28/2015] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND ACAT-related enzyme 2 required for viability 1 (ARV1) is a putative lipid transporter of the endoplasmic reticulum that is conserved across eukaryotic species. The ARV1 protein contains a conserved N-terminal cytosolic zinc ribbon motif known as the ARV1 homology domain, followed by multiple transmembrane regions anchoring it in the ER. Deletion of ARV1 in yeast results in defective sterol trafficking, aberrant lipid synthesis, ER stress, membrane disorganization and hypersensitivity to fatty acids (FAs). We sought to investigate the role of Arv1 in mammalian lipid metabolism. METHODS Homologous recombination was used to disrupt the Arv1 gene in mice. Animals were examined for alterations in lipid and lipoprotein levels, body weight, body composition, glucose tolerance and energy expenditure. RESULTS Global loss of Arv1 significantly decreased total cholesterol and high-density lipoprotein cholesterol levels in the plasma. Arv1 knockout mice exhibited a dramatic lean phenotype, with major reductions in white adipose tissue (WAT) mass and body weight on a chow diet. This loss of WAT is accompanied by improved glucose tolerance, higher adiponectin levels, increased energy expenditure and greater rates of whole-body FA oxidation. CONCLUSIONS This work identifies Arv1 as an important player in mammalian lipid metabolism and whole-body energy homeostasis.
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Affiliation(s)
- W R Lagor
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - F Tong
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - K E Jarrett
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - W Lin
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - D M Conlon
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M Smith
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M Y Wang
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - B O Yenilmez
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M G McCoy
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - D W Fields
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - S M O'Neill
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - R Gupta
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - A Kumaravel
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - V Redon
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - R S Ahima
- Division of Endocrinology, Diabetes and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - S L Sturley
- Department of Pediatrics, Columbia University Medical Center, New York, NY, USA
| | - J T Billheimer
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - D J Rader
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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11
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Ruggles KV, Garbarino J, Liu Y, Moon J, Schneider K, Henneberry A, Billheimer J, Millar JS, Marchadier D, Valasek MA, Joblin-Mills A, Gulati S, Munkacsi AB, Repa JJ, Rader D, Sturley SL. A functional, genome-wide evaluation of liposensitive yeast identifies the "ARE2 required for viability" (ARV1) gene product as a major component of eukaryotic fatty acid resistance. J Biol Chem 2013; 289:4417-31. [PMID: 24273168 DOI: 10.1074/jbc.m113.515197] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The toxic subcellular accumulation of lipids predisposes several human metabolic syndromes, including obesity, type 2 diabetes, and some forms of neurodegeneration. To identify pathways that prevent lipid-induced cell death, we performed a genome-wide fatty acid sensitivity screen in Saccharomyces cerevisiae. We identified 167 yeast mutants as sensitive to 0.5 mm palmitoleate, 45% of which define pathways that were conserved in humans. 63 lesions also impacted the status of the lipid droplet; however, this was not correlated to the degree of fatty acid sensitivity. The most liposensitive yeast strain arose due to deletion of the "ARE2 required for viability" (ARV1) gene, encoding an evolutionarily conserved, potential lipid transporter that localizes to the endoplasmic reticulum membrane. Down-regulation of mammalian ARV1 in MIN6 pancreatic β-cells or HEK293 cells resulted in decreased neutral lipid synthesis, increased fatty acid sensitivity, and lipoapoptosis. Conversely, elevated expression of human ARV1 in HEK293 cells or mouse liver significantly increased triglyceride mass and lipid droplet number. The ARV1-induced hepatic triglyceride accumulation was accompanied by up-regulation of DGAT1, a triglyceride synthesis gene, and the fatty acid transporter, CD36. Furthermore, ARV1 was identified as a transcriptional of the protein peroxisome proliferator-activated receptor α (PPARα), a key regulator of lipid homeostasis whose transcriptional targets include DGAT1 and CD36. These results implicate ARV1 as a protective factor in lipotoxic diseases due to modulation of fatty acid metabolism. In conclusion, a lipotoxicity-based genetic screen in a model microorganism has identified 75 human genes that may play key roles in neutral lipid metabolism and disease.
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12
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Gallo-Ebert C, McCourt PC, Donigan M, Villasmil ML, Chen W, Pandya D, Franco J, Romano D, Chadwick SG, Gygax SE, Nickels JT. Arv1 lipid transporter function is conserved between pathogenic and nonpathogenic fungi. Fungal Genet Biol 2011; 49:101-13. [PMID: 22142782 DOI: 10.1016/j.fgb.2011.11.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 11/10/2011] [Accepted: 11/16/2011] [Indexed: 10/14/2022]
Abstract
The lipid transporter Arv1 regulates sterol trafficking, and glycosylphosphatidylinositol and sphingolipid biosyntheses in Saccharomyces cerevisiae. ScArv1 contains an Arv1 homology domain (AHD) that is conserved at the amino acid level in the pathogenic fungal species, Candida albicans and Candida glabrata. Here we show S. cerevisiae cells lacking Arv1 are highly susceptible to antifungal drugs. In the presence of drug, Scarv1 cells are unable to induce ERG gene expression, have an altered pleiotrophic drug response, and are defective in multi-drug resistance efflux pump expression. All phenotypes are remediated by ectopic expression of CaARV1 or CgARV1. The AHDs of these pathogenic fungi are required for specific drug tolerance, demonstrating conservation of function. In order to understand how Arv1 regulates antifungal susceptibility, we examined sterol trafficking. CaARV1/CgARV1 expression suppressed the sterol trafficking defect of Scarv1 cells. Finally, we show that C. albicansarv1/arv1 cells are avirulent using a BALB/c disseminated mouse model. We suggest that overall cell survival in response to antifungal treatment requires the lipid transporter function of Arv1.
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13
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The putative lipid transporter, Arv1, is required for activating pheromone-induced MAP kinase signaling in Saccharomyces cerevisiae. Genetics 2010; 187:455-65. [PMID: 21098723 DOI: 10.1534/genetics.110.120725] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Saccharomyces cerevisiae haploid cells respond to extrinsic mating signals by forming polarized projections (shmoos), which are necessary for conjugation. We have examined the role of the putative lipid transporter, Arv1, in yeast mating, particularly the conserved Arv1 homology domain (AHD) within Arv1 and its role in this process. Previously it was shown that arv1 cells harbor defects in sphingolipid and glycosylphosphatidylinositol (GPI) biosyntheses and may harbor sterol trafficking defects. Here we demonstrate that arv1 cells are mating defective and cannot form shmoos. They lack the ability to initiate pheromone-induced G1 cell cycle arrest, due to failure to polarize PI(4,5)P(2) and the Ste5 scaffold, which results in weakened MAP kinase signaling activity. A mutant Ste5, Ste5(Q59L), which binds more tightly to the plasma membrane, suppresses the MAP kinase signaling defects of arv1 cells. Filipin staining shows arv1 cells contain altered levels of various sterol microdomains that persist throughout the mating process. Data suggest that the sterol trafficking defects of arv1 affect PI(4,5)P(2) polarization, which causes a mislocalization of Ste5, resulting in defective MAP kinase signaling and the inability to mate. Importantly, our studies show that the AHD of Arv1 is required for mating, pheromone-induced G1 cell cycle arrest, and for sterol trafficking.
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14
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Busquets A, Keim V, Closa M, del Arco A, Boronat A, Arró M, Ferrer A. Arabidopsis thaliana contains a single gene encoding squalene synthase. PLANT MOLECULAR BIOLOGY 2008; 67:25-36. [PMID: 18236008 DOI: 10.1007/s11103-008-9299-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Accepted: 01/16/2008] [Indexed: 05/21/2023]
Abstract
Squalene synthase (SQS) catalyzes the condensation of two molecules of farnesyl diphosphate (FPP) to produce squalene (SQ), the first committed precursor for sterol, brassinosteroid, and triterpene biosynthesis. Arabidopsis thaliana contains two SQS-annotated genomic sequences, At4g34640 (SQS1) and At4g34650 (SQS2), organized in a tandem array. Here we report that the SQS1 gene is widely expressed in all tissues throughout plant development, whereas SQS2 is primarily expressed in the vascular tissue of leaf and cotyledon petioles, and the hypocotyl of seedlings. Neither the complete A. thaliana SQS2 protein nor the chimeric SQS resulting from the replacement of the 69 C-terminal residues of SQS2 by the 111 C-terminal residues of the Schizosaccharomyces pombe SQS were able to confer ergosterol prototrophy to a Saccharomyces cerevisiae erg9 mutant strain lacking SQS activity. A soluble form of SQS2 expressed in Escherichia coli and purified was unable to synthesize SQ from FPP in the presence of NADPH and either Mg2+ or Mn2+. These results demonstrated that SQS2 has no SQS activity, so that SQS1 is the only functional SQS in A. thaliana. Mutational studies revealed that the lack of SQS activity of SQS2 cannot be exclusively attributed to the presence of an unusual Ser replacing the highly conserved Phe at position 287. Expression of green fluorescent protein (GFP)-tagged versions of SQS1 in onion epidermal cells demonstrated that SQS1 is targeted to the endoplasmic reticulum (ER) membrane and that this location is exclusively dependent on the presence of the SQS1 C-terminal hydrophobic trans-membrane domain.
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Affiliation(s)
- Antoni Busquets
- Departament de Bioquímica i Biologia Molecular, Facultat de Farmàcia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, Spain
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15
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Kajiwara K, Watanabe R, Pichler H, Ihara K, Murakami S, Riezman H, Funato K. Yeast ARV1 is required for efficient delivery of an early GPI intermediate to the first mannosyltransferase during GPI assembly and controls lipid flow from the endoplasmic reticulum. Mol Biol Cell 2008; 19:2069-82. [PMID: 18287539 DOI: 10.1091/mbc.e07-08-0740] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Glycosylphosphatidylinositol (GPI), covalently attached to many eukaryotic proteins, not only acts as a membrane anchor but is also thought to be a sorting signal for GPI-anchored proteins that are associated with sphingolipid and sterol-enriched domains. GPI anchors contain a core structure conserved among all species. The core structure is synthesized in two topologically distinct stages on the leaflets of the endoplasmic reticulum (ER). Early GPI intermediates are assembled on the cytoplasmic side of the ER and then are flipped into the ER lumen where a complete GPI precursor is synthesized and transferred to protein. The flipping process is predicted to be mediated by a protein referred as flippase; however, its existence has not been proven. Here we show that yeast Arv1p is an important protein required for the delivery of an early GPI intermediate, GlcN-acylPI, to the first mannosyltransferase of GPI synthesis in the ER lumen. We also provide evidence that ARV1 deletion and mutations in other proteins involved in GPI anchor synthesis affect inositol phosphorylceramide synthesis as well as the intracellular distribution and amounts of sterols, suggesting a role of GPI anchor synthesis in lipid flow from the ER.
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Affiliation(s)
- Kentaro Kajiwara
- Department of Bioresource Science and Technology, Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan
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