1
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Flannery KP, Safwat S, Matsell E, Battula N, Hamed AAA, Mohamed IN, Elseed MA, Koko M, Abubaker R, Abozar F, Elsayed LEO, Bhise V, Molday RS, Salih MA, Yahia A, Manzini MC. A novel missense variant in the ATPase domain of ATP8A2 and review of phenotypic variability of ATP8A2-related disorders caused by missense changes. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.05.15.24306843. [PMID: 38798571 PMCID: PMC11118633 DOI: 10.1101/2024.05.15.24306843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
ATPase, class 1, type 8A, member 2 (ATP8A2) is a P4-ATPase with a critical role in phospholipid translocation across the plasma membrane. Pathogenic variants in ATP8A2 are known to cause cerebellar ataxia, mental retardation, and disequilibrium syndrome 4 (CAMRQ4) which is often associated with encephalopathy, global developmental delay, and severe motor deficits. Here, we present a family with two siblings presenting with global developmental delay, intellectual disability, spasticity, ataxia, nystagmus, and thin corpus callosum. Whole exome sequencing revealed a homozygous missense variant in the nucleotide binding domain of ATP8A2 (p.Leu538Pro) that results in near complete loss of protein expression. This is in line with other missense variants in the same domain leading to protein misfolding and loss of ATPase function. In addition, by performing diffusion-weighted imaging, we identified bilateral hyperintensities in the posterior limbs of the internal capsule suggesting possible microstructural changes in axon tracts that had not been appreciated before and could contribute to the sensorimotor deficits in these individuals.
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Affiliation(s)
- Kyle P. Flannery
- Department of Neuroscience & Cell Biology, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08901
| | - Sylvia Safwat
- Department of Neuroscience & Cell Biology, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08901
- Department of Human Genetics, Medical Research Institute, Alexandria University, Alexandria, Egypt
| | - Eli Matsell
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
| | - Namarata Battula
- Department of Neuroscience & Cell Biology, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08901
| | | | | | - Maha A. Elseed
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | - Mahmoud Koko
- Institute of Endemic Diseases, University of Khartoum, Khartoum, Sudan
| | - Rayan Abubaker
- Sudanese Neurogenetics Research group, Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | - Fatima Abozar
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | - Liena E. O. Elsayed
- Department of Basic Sciences, College of Medicine, Princess Nourah bint Abdulrahman University, Riyadh, P.O.Box 84428, Riyadh 11671, Saudi Arabia
| | - Vikram Bhise
- Department of Pediatrics and Neurology, Rutgers – Robert Wood Johnson Medical School, New Brunswick, NJ, USA
| | - Robert S. Molday
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
| | - Mustafa A. Salih
- Consultant Pediatric Neurologist, Health Sector, King Abdulaziz City for Science and Technology, Riyadh 11442, Saudi Arabia
| | - Ashraf Yahia
- Department of Biochemistry, Faculty of Medicine, University of Khartoum, Khartoum, Sudan
- Center of Neurodevelopmental Disorders (KIND), Centre for Psychiatry Research, Department of Women’s and Children’s Health, Karolinska Institutet and Stockholm Health Care Services, Region Stockholm, Stockholm, Sweden
- Astrid Lindgren Children’s Hospital, Karolinska University Hospital, Solna, Sweden
| | - M. Chiara Manzini
- Department of Neuroscience & Cell Biology, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ 08901
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2
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Teov B, Janchevska A, Beqiri-Jasari A, Tasic V, Kungulovski G, Gucev Z. Compound Heterozygosity in Cerebellar Ataxia, Mental Retardation, and Disequilibrium Syndrome Type 4. Pril (Makedon Akad Nauk Umet Odd Med Nauki) 2023; 44:85-90. [PMID: 38109455 DOI: 10.2478/prilozi-2023-0051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Cerebellar ataxia, mental retardation, and disequilibrium syndrome (CAMRQ) is a genetically and clinically heterogeneous disorder with four described subtypes. Autosomal recessive syndrome of cerebellar ataxia, mental retardation, and disequilibrium type 4 (CAMRQ4) is caused by mutations in the ATP8A2 gene. We report an 8-year-old boy with choreoathetosis, hypotonia, without the ability to keep his head up and profound mental retardation. There was quadrupedal locomotion, as well. MRI of the brain revealed a hypotrophy of the corpus callosum, diffuse white matter reduction, widespread delayed myelination and ventriculomegaly. Trio whole-exome sequencing revealed compound heterozygosity in the ATP8A2 gene consisting of a known variant c.1756C>T (p.Arg586*) inherited from the mother and a novel variant c.691_701delCTGATGAAGTT (p.Leu231fs) inherited from the father. CAMRQ type 4 has been found in about 50 patients. To the best of our knowledge, this is the first reported patient with CAMRQ4 with these gene variants. The clinical presentation is severe.
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Affiliation(s)
- Bojan Teov
- 1University Children's Hospital, Medical Faculty Skopje, North Macedonia
| | | | | | - Velibor Tasic
- 1University Children's Hospital, Medical Faculty Skopje, North Macedonia
| | | | - Zoran Gucev
- 1University Children's Hospital, Medical Faculty Skopje, North Macedonia
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3
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Alves Corazza L, Lopes Braga V, Yoshinaga Tonholo Silva T, Moura Rezende Filho F, Ferraz Sallum JM, Graziani Povoas Barsottini O, Pedroso JL. ATP8A2-Related Disorder: Beyond Cerebellar Ataxia. Mov Disord Clin Pract 2023; 10:1215-1216. [PMID: 37635783 PMCID: PMC10450237 DOI: 10.1002/mdc3.13820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/17/2023] [Accepted: 06/11/2023] [Indexed: 08/29/2023] Open
Affiliation(s)
- Luíza Alves Corazza
- Department of Neurology and Neurosurgery, Escola Paulista de MedicinaUniversidade Federal de São Paulo (UNIFESP)São PauloBrazil
| | - Vinícius Lopes Braga
- Department of Neurology and Neurosurgery, Escola Paulista de MedicinaUniversidade Federal de São Paulo (UNIFESP)São PauloBrazil
| | - Thiago Yoshinaga Tonholo Silva
- Department of Neurology and Neurosurgery, Escola Paulista de MedicinaUniversidade Federal de São Paulo (UNIFESP)São PauloBrazil
| | - Flávio Moura Rezende Filho
- Department of Neurology and Neurosurgery, Escola Paulista de MedicinaUniversidade Federal de São Paulo (UNIFESP)São PauloBrazil
| | - Juliana Maria Ferraz Sallum
- Department of Neurology and Neurosurgery, Escola Paulista de MedicinaUniversidade Federal de São Paulo (UNIFESP)São PauloBrazil
| | | | - José Luiz Pedroso
- Department of Neurology and Neurosurgery, Escola Paulista de MedicinaUniversidade Federal de São Paulo (UNIFESP)São PauloBrazil
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4
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Sun Q, Zhang X, Zhan P, Tian W, Wang Y, Yang X. Analysis of 2 men with t(8;22)(q13;q13) and t(8;14)(q13;q22) chromosomal translocation karyotypes. Medicine (Baltimore) 2022; 101:e31091. [PMID: 36254019 PMCID: PMC9575810 DOI: 10.1097/md.0000000000031091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Male infertility is a multifactorial condition that is closely associated with chromosomal abnormalities. Reciprocal chromosomal translocation (RCT) is a significant structural genetic abnormality. The specific mechanisms of forms of RCT affecting male infertility include the product of chromosomally unbalanced gametes, thereby disrupting the structure and function of important genes responsible for spermatogenesis. RCT breakpoints have been found to disrupt gene structure and function in many medical fields However, the relationship between RCT breakpoints and male infertility remains to be determined. The purpose of this study is to describe 2 male carriers of RCTs 46,XY,t(8;22)(q13;q13) and 46,XY,t(8;14)(q13;q22). Both patients were collected from the second hospital of Jilin University. Semen parameters were detected using the computer-aided semen analysis system. Cytogenetic analysis was performed using standard operating procedure. Related genes on chromosomal breakpoints were searched using Online Mendelian Inheritance in Man. One man had semen parameters within the normal range, but the couple was infertile after 5 years of marriage. The other man showed normal semen parameters, and his wife had experienced 2 spontaneous miscarriages. Using a literature search, the association between chromosome 22q13 breakpoint and fertility were investigated. The results suggest that physicians should focus on the clinical phenotype of the patients and the breakpoints of RCT in genetic counseling. An important gene related to human male infertility is clearly located in chromosome region 22q13, and its function is worthy of further study.
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Affiliation(s)
- Qijia Sun
- Department of Urology, The Second Hospital of Jilin University, Changchun, China
| | - Xiaoyu Zhang
- Department of Urology, The Second Hospital of Jilin University, Changchun, China
| | - Peng Zhan
- Department of Urology, The Second Hospital of Jilin University, Changchun, China
- * Correspondence: Peng Zhan, Department of Urology, The Second Hospital of Jilin University, 218 Ziqiang Street, Nanguan District, Changchun, Jilin Province 130041, China (e-mail: )
| | - Wenjie Tian
- Department of Urology, The Second Hospital of Jilin University, Changchun, China
| | - Yanli Wang
- Department of Urology, The Second Hospital of Jilin University, Changchun, China
| | - Xiao Yang
- Department of Urology, The Second Hospital of Jilin University, Changchun, China
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5
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Shin HW, Takatsu H. Regulatory Roles of N- and C-Terminal Cytoplasmic Regions of P4-ATPases. Chem Pharm Bull (Tokyo) 2022; 70:524-532. [DOI: 10.1248/cpb.c22-00042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hye-Won Shin
- Graduate School of Pharmaceutical Sciences, Kyoto University
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6
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Annexin A5 as a targeting agent for cancer treatment. Cancer Lett 2022; 547:215857. [DOI: 10.1016/j.canlet.2022.215857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 11/19/2022]
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7
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Lipid Dyshomeostasis and Inherited Cerebellar Ataxia. Mol Neurobiol 2022; 59:3800-3828. [PMID: 35420383 PMCID: PMC9148275 DOI: 10.1007/s12035-022-02826-2] [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: 03/29/2021] [Accepted: 04/01/2022] [Indexed: 12/04/2022]
Abstract
Cerebellar ataxia is a form of ataxia that originates from dysfunction of the cerebellum, but may involve additional neurological tissues. Its clinical symptoms are mainly characterized by the absence of voluntary muscle coordination and loss of control of movement with varying manifestations due to differences in severity, in the site of cerebellar damage and in the involvement of extracerebellar tissues. Cerebellar ataxia may be sporadic, acquired, and hereditary. Hereditary ataxia accounts for the majority of cases. Hereditary ataxia has been tentatively divided into several subtypes by scientists in the field, and nearly all of them remain incurable. This is mainly because the detailed mechanisms of these cerebellar disorders are incompletely understood. To precisely diagnose and treat these diseases, studies on their molecular mechanisms have been conducted extensively in the past. Accumulating evidence has demonstrated that some common pathogenic mechanisms exist within each subtype of inherited ataxia. However, no reports have indicated whether there is a common mechanism among the different subtypes of inherited cerebellar ataxia. In this review, we summarize the available references and databases on neurological disorders characterized by cerebellar ataxia and show that a subset of genes involved in lipid homeostasis form a new group that may cause ataxic disorders through a common mechanism. This common signaling pathway can provide a valuable reference for future diagnosis and treatment of ataxic disorders.
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Narishige Y, Yaoita H, Shibuya M, Ikeda M, Kodama K, Kawahima A, Okubo Y, Endo W, Inui T, Togashi N, Tanaka S, Kobayashi Y, Onuma A, Takayama J, Tamiya G, Kikuchi A, Kure S, Haginoya K. Two Siblings with Cerebellar Ataxia, Mental Retardation, and Disequilibrium Syndrome 4 and a Novel Variant of ATP8A2. TOHOKU J EXP MED 2022; 256:321-326. [PMID: 35321980 DOI: 10.1620/tjem.2022.j010] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Yuta Narishige
- Department of Pediatric Neurology, Miyagi Children's Hospital
| | - Hisao Yaoita
- Department of Pediatrics, Tohoku University School of Medicine
| | - Moriei Shibuya
- Department of Pediatric Neurology, Miyagi Children's Hospital
| | - Miki Ikeda
- Department of Pediatric Neurology, Miyagi Children's Hospital
| | - Kaori Kodama
- Department of Pediatric Neurology, Miyagi Children's Hospital
| | | | - Yukimune Okubo
- Department of Pediatric Neurology, Miyagi Children's Hospital
| | - Wakaba Endo
- Department of Pediatric Neurology, Miyagi Children's Hospital
| | - Takehiko Inui
- Department of Pediatric Neurology, Miyagi Children's Hospital
| | - Noriko Togashi
- Department of Pediatric Neurology, Miyagi Children's Hospital
| | - Soichiro Tanaka
- Department of Pediatric Neurology, Miyagi Children's Hospital.,Department of Pediatric Neurology, Takuto Rehabilitation Center for Children
| | - Yasuko Kobayashi
- Department of Pediatric Neurology, Takuto Rehabilitation Center for Children
| | - Akira Onuma
- Department of Pediatric Neurology, Takuto Rehabilitation Center for Children
| | - Jun Takayama
- Tohoku University Graduate School of Medicine.,Tohoku Medical Megabank Organization, Tohoku University.,Statistical Genetics Team, RIKEN Center for Advanced Intelligence Project
| | - Gen Tamiya
- Tohoku University Graduate School of Medicine.,Tohoku Medical Megabank Organization, Tohoku University.,Statistical Genetics Team, RIKEN Center for Advanced Intelligence Project
| | - Atsuo Kikuchi
- Department of Pediatrics, Tohoku University School of Medicine
| | - Shigeo Kure
- Department of Pediatrics, Tohoku University School of Medicine
| | - Kazuhiro Haginoya
- Department of Pediatric Neurology, Miyagi Children's Hospital.,Department of Pediatric Neurology, Takuto Rehabilitation Center for Children
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9
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Biallelic truncation variants in ATP9A are associated with a novel autosomal recessive neurodevelopmental disorder. NPJ Genom Med 2021; 6:94. [PMID: 34764295 PMCID: PMC8586153 DOI: 10.1038/s41525-021-00255-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 10/04/2021] [Indexed: 12/12/2022] Open
Abstract
Intellectual disability (ID) is a highly heterogeneous disorder with hundreds of associated genes. Despite progress in the identification of the genetic causes of ID following the introduction of high-throughput sequencing, about half of affected individuals still remain without a molecular diagnosis. Consanguineous families with affected individuals provide a unique opportunity to identify novel recessive causative genes. In this report, we describe a novel autosomal recessive neurodevelopmental disorder. We identified two consanguineous families with homozygous variants predicted to alter the splicing of ATP9A which encodes a transmembrane lipid flippase of the class II P4-ATPases. The three individuals homozygous for these putatively truncating variants presented with severe ID, motor and speech impairment, and behavioral anomalies. Consistent with a causative role of ATP9A in these patients, a previously described Atp9a−/− mouse model showed behavioral changes.
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10
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Damásio J, Santos D, Morais S, Brás J, Guerreiro R, Sardoeira A, Cavaco S, Carrilho I, Barbot C, Barros J, Sequeiros J. Congenital ataxia due to novel variant in ATP8A2. Clin Genet 2021; 100:79-83. [PMID: 33682124 DOI: 10.1111/cge.13954] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 03/03/2021] [Accepted: 03/05/2021] [Indexed: 01/22/2023]
Abstract
Congenital ataxias are a heterogeneous group of disorders characterized by congenital or early-onset ataxia. Here, we describe two siblings with congenital ataxia, who acquired independent gait by age 4 years. After 16 years of follow-up they presented near normal cognition, cerebellar ataxia, mild pyramidal signs, and dystonia. On exome sequencing, a novel homozygous variant (c.1580-18C > G - intron 17) in ATP8A2 was identified. A new acceptor splice site was predicted by bioinformatics tools, and functionally characterized through a minigene assay. Minigene constructs were generated by PCR-amplification of genomic sequences surrounding the variant of interest and cloning into the pCMVdi vector. Altered splicing was evaluated by expressing these constructs in HEK293T cells. The construct with the c.1580-18C > G homozygous variant produced an aberrant transcript, leading to retention of 17 bp of intron 17, by the use of an alternative acceptor splice site, resulting in a premature stop codon by insertion of four amino acids. These results allowed us to establish this as a disease-causing variant and expand ATP8A2-related disorders to include less severe forms of congenital ataxia.
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Affiliation(s)
- Joana Damásio
- UnIGENe/CGPP - Instituto de Biologia Molecular e Celular, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Serviço Neurologia, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Diana Santos
- UnIGENe/CGPP - Instituto de Biologia Molecular e Celular, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Sara Morais
- UnIGENe/CGPP - Instituto de Biologia Molecular e Celular, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - José Brás
- Center for Neurodegenerative Science, Van Andel Research Institute, Grand Rapids, Michigan, USA.,Division of Psychiatry and Behavioral Medicine, Michigan State University College of Human Medicine, Grand Rapids, Michigan, USA
| | - Rita Guerreiro
- Center for Neurodegenerative Science, Van Andel Research Institute, Grand Rapids, Michigan, USA.,Division of Psychiatry and Behavioral Medicine, Michigan State University College of Human Medicine, Grand Rapids, Michigan, USA
| | - Ana Sardoeira
- Serviço Neurologia, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Sara Cavaco
- Unidade Neuropsicologia, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Inês Carrilho
- Unidade Neurologia Pediátrica, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Clara Barbot
- UnIGENe/CGPP - Instituto de Biologia Molecular e Celular, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - José Barros
- Serviço Neurologia, Centro Hospitalar Universitário do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Jorge Sequeiros
- UnIGENe/CGPP - Instituto de Biologia Molecular e Celular, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Porto, Portugal
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11
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Heidari E, Harrison AN, Jafarinia E, Tavasoli AR, Almadani N, Molday RS, Garshasbi M. Novel variants in critical domains of ATP8A2 and expansion of clinical spectrum. Hum Mutat 2021; 42:491-497. [PMID: 33565221 DOI: 10.1002/humu.24180] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 01/17/2021] [Accepted: 02/07/2021] [Indexed: 12/12/2022]
Abstract
ATP8A2 is a P4-ATPase that flips phosphatidylserine across membranes to generate and maintain transmembrane phospholipid asymmetry. Loss-of-function variants cause severe neurodegenerative and developmental disorders. We have identified three ATP8A2 variants in unrelated Iranian families that cause intellectual disability, dystonia, below-average head circumference, mild optic atrophy, and developmental delay. Additionally, all the affected individuals displayed tooth abnormalities associated with defects in teeth development. Two variants (p.Asp825His and p.Met438Val) reside in critical functional domains of ATP8A2. These variants express at very low levels and lack ATPase activity. Inhibitor studies indicate that these variants are misfolded and degraded by the cellular proteasome. We conclude that Asp825, which coordinates with the Mg2+ ion within the ATP binding site, and Met438 are essential for the proper folding of ATP8A2 into a functional flippase. We also provide evidence on the association of tooth abnormalities with defects in ATP8A2, thereby expanding the clinical spectrum of the associated disease.
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Affiliation(s)
- Erfan Heidari
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Alexander N Harrison
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ehsan Jafarinia
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Ali Reza Tavasoli
- Division of Pediatric Neurology, Myelin Disorders Clinic, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Navid Almadani
- Department of Genetics, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
| | - Robert S Molday
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Masoud Garshasbi
- Department of Medical Genetics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
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12
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Genome-wide association study for postweaning weight traits in Lori-Bakhtiari sheep. Trop Anim Health Prod 2021; 53:163. [PMID: 33586021 DOI: 10.1007/s11250-021-02595-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/27/2021] [Indexed: 01/20/2023]
Abstract
Marker-assisted selection is an effective method in novel animal breeding programs. This study was conducted to perform a genome-wide association study to detect candidate genes and quantitative trait loci associated with postweaning weight traits in meat-type sheep. Body weight records were collected during 29 years (1989 to 2017) in Lori-Bakhtiari sheep flock of the Shooli Breeding Station in Iran. A total of 132 animals were selected based on estimates of breeding values (EBVs) for body weight, using two-tailed and random selection strategies. Genomic DNA was extracted from whole blood samples. The samples were genotyped using Illumina OvineSNP50 BeadChip. De-regressed EBVs for postweaning body weight traits were used as pseudo-phenotypes in a genome-wide association study. One SNP on chromosome 10 (rs406324209) and two SNPs on chromosome 13 (rs401963094 and rs418761613) were significantly (Bonferroni-adjusted p-values < 0.05) associated with postweaning body weight traits. The significant variants accounted for 0.20% and 0.48% of the total genetic variances for 6- and 9-month body weights, respectively. Genomic heritabilities estimated for 6-, 9- and 12-month weights and postweaning weight gain were 0.28 ± 0.34, 0.35 ± 0.29, 0.37 ± 0.34, and 0.16 ± 0.33, respectively. Two significant SNPs were located within the ATP8A2 and PLXDC2 genes, on chromosomes 10 and 13, respectively. Based on the known gene ontologies, both ATP8A2 and PLXDC2 could be considered as candidate genes for postweaning body weight traits.
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13
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Mohamadian M, Ghandil P, Naseri M, Bahrami A, Momen AA. A novel homozygous variant in an Iranian pedigree with cerebellar ataxia, mental retardation, and dysequilibrium syndrome type 4. J Clin Lab Anal 2020; 34:e23484. [PMID: 33079427 PMCID: PMC7676196 DOI: 10.1002/jcla.23484] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/12/2020] [Accepted: 06/26/2020] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Cerebellar ataxia, mental retardation, and dysequilibrium (CAMRQ) syndrome is a rare and early-onset neurodevelopmental disorder. Four subtypes of this syndrome have been identified, which are clinically and genetically different. To date, altogether 32 patients have been described with ATP8A2 mutations and phenotypic features assigned to CAMRQ type 4. Herein, three additional patients in an Iranian consanguineous family with non-progressive cerebellar ataxia, severe hypotonia, intellectual disability, dysarthria, and cerebellar atrophy have been identified. METHODS Following the thorough clinical examination, consecutive detections including chromosome karyotyping, chromosomal microarray analysis, and whole exome sequencing (WES) were performed on the proband. The sequence variants derived from WES interpreted by a standard bioinformatics pipeline. Pathogenicity assessment of candidate variant was done by in silico analysis. The familial cosegregation of the WES finding was carried out by PCR-based Sanger sequencing. RESULTS A novel homozygous missense variant (c.1339G > A, p.Gly447Arg) in the ATP8A2 gene was identified and completely segregated with the phenotype in the family. In silico analysis and structural modeling revealed that the p.G477R substitution is deleterious and induced undesired effects on the protein stability and residue distribution in the ligand-binding pocket. The novel sequence variant occurred within an extremely conserved subregion of the ATP-binding domain. CONCLUSION Our findings expand the spectrum of ATP8A2 mutations and confirm the reported genotype-phenotype correlation. These results could improve genetic counseling and prenatal diagnosis in families with clinical presentations related to CAMRQ4 syndrome.
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Affiliation(s)
- Malihe Mohamadian
- Department of Molecular Medicine, Birjand University of Medical Sciences, Birjand, Iran
| | - Pegah Ghandil
- Diabetes Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Department of Medical Genetics, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mohsen Naseri
- Cellular and Molecular Research Center, Birjand University of Medical Sciences, Birjand, Iran
| | - Afsane Bahrami
- Cellular and Molecular Research Center, Birjand University of Medical Sciences, Birjand, Iran
| | - Ali Akbar Momen
- Department of Paediatric Neurology, Golestan Medical, Educational, and Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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14
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Baizabal-Carvallo JF, Cardoso F. Chorea in children: etiology, diagnostic approach and management. J Neural Transm (Vienna) 2020; 127:1323-1342. [DOI: 10.1007/s00702-020-02238-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/01/2020] [Indexed: 01/07/2023]
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15
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Céspedes PF, Beckers D, Dustin ML, Sezgin E. Model membrane systems to reconstitute immune cell signaling. FEBS J 2020; 288:1070-1090. [DOI: 10.1111/febs.15488] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/26/2020] [Accepted: 07/14/2020] [Indexed: 12/26/2022]
Affiliation(s)
- Pablo F. Céspedes
- Kennedy Institute of Rheumatology Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences University of Oxford UK
| | - Daniel Beckers
- MRC Human Immunology Unit MRC Weatherall Institute of Molecular Medicine University of Oxford UK
| | - Michael L. Dustin
- Kennedy Institute of Rheumatology Nuffield Department of Orthopedics, Rheumatology and Musculoskeletal Sciences University of Oxford UK
| | - Erdinc Sezgin
- MRC Human Immunology Unit MRC Weatherall Institute of Molecular Medicine University of Oxford UK
- Science for Life Laboratory Department of Women's and Children's Health Karolinska Institutet Stockholm Sweden
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16
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Affiliation(s)
- Hye-Won Shin
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Hiroyuki Takatsu
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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17
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Nagata S, Sakuragi T, Segawa K. Flippase and scramblase for phosphatidylserine exposure. Curr Opin Immunol 2020; 62:31-38. [DOI: 10.1016/j.coi.2019.11.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 11/25/2019] [Indexed: 01/30/2023]
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18
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Guissart C, Harrison AN, Benkirane M, Oncel I, Arslan EA, Chassevent AK., Baraῆano K, Larrieu L, Iascone M, Tenconi R, Claustres M, Eroglu-Ertugrul N, Calvas P, Topaloglu H, Molday RS, Koenig M. ATP8A2-related disorders as recessive cerebellar ataxia. J Neurol 2019; 267:203-213. [DOI: 10.1007/s00415-019-09579-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/06/2019] [Accepted: 10/10/2019] [Indexed: 02/03/2023]
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19
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Choi H, Andersen JP, Molday RS. Expression and functional characterization of missense mutations in ATP8A2 linked to severe neurological disorders. Hum Mutat 2019; 40:2353-2364. [PMID: 31397519 DOI: 10.1002/humu.23889] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/30/2019] [Accepted: 08/04/2019] [Indexed: 11/09/2022]
Abstract
ATP8A2 is a P4-ATPase (adenosine triphosphate) that actively flips phosphatidylserine and phosphatidylethanolamine from the exoplasmic to the cytoplasmic leaflet of cell membranes to generate and maintain phospholipid asymmetry. Mutations in the ATP8A2 gene have been reported to cause severe autosomal recessive neurological diseases in humans characterized by intellectual disability, hypotonia, chorea, and hyperkinetic movement disorders with or without optic and cerebellar atrophy. To determine the effect of disease-associated missense mutations on ATP8A2, we expressed six variants with the accessory subunit CDC50A in HEK293T cells. The level of expression, cellular localization, and functional activity were analyzed by western blot analysis, immunofluorescence microscopy, and ATPase activity assays. Two variants (p.Ile376Met and p.Lys429Met) expressed at normal ATP8A2 levels and preferentially localized to the Golgi-recycling endosomes, but were devoid of ATPase activity. Four variants (p.Lys429Asn, pAla544Pro, p.Arg625Trp, and p.Trp702Arg) expressed poorly, localized to the endoplasmic reticulum, and lacked ATPase activity. The expression of these variants was increased twofold by the addition of the proteasome inhibitor MG132. We conclude that the p.Ile376Met and p.Lys429Met variants fold in a native-like conformation, but lack key amino acid residues required for ATP-dependent lipid transport. In contrast, the p.Lys429Asn, pAla544Pro, p.Arg625Trp, and p.Trp702Arg variants are highly misfolded and undergo rapid proteosomal degradation.
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Affiliation(s)
- Hanbin Choi
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jens P Andersen
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
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20
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Phosphatidylserine flipping by the P4-ATPase ATP8A2 is electrogenic. Proc Natl Acad Sci U S A 2019; 116:16332-16337. [PMID: 31371510 DOI: 10.1073/pnas.1910211116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Phospholipid flippases (P4-ATPases) utilize ATP to translocate specific phospholipids from the exoplasmic leaflet to the cytoplasmic leaflet of biological membranes, thus generating and maintaining transmembrane lipid asymmetry essential for a variety of cellular processes. P4-ATPases belong to the P-type ATPase protein family, which also encompasses the ion transporting P2-ATPases: Ca2+-ATPase, Na+,K+-ATPase, and H+,K+-ATPase. In comparison with the P2-ATPases, understanding of P4-ATPases is still very limited. The electrogenicity of P4-ATPases has not been explored, and it is not known whether lipid transfer between membrane bilayer leaflets can lead to displacement of charge across the membrane. A related question is whether P4-ATPases countertransport ions or other substrates in the opposite direction, similar to the P2-ATPases. Using an electrophysiological method based on solid supported membranes, we observed the generation of a transient electrical current by the mammalian P4-ATPase ATP8A2 in the presence of ATP and the negatively charged lipid substrate phosphatidylserine, whereas only a diminutive current was generated with the lipid substrate phosphatidylethanolamine, which carries no or little charge under the conditions of the measurement. The current transient seen with phosphatidylserine was abolished by the mutation E198Q, which blocks dephosphorylation. Likewise, mutation I364M, which causes the neurological disorder cerebellar ataxia, mental retardation, and disequilibrium (CAMRQ) syndrome, strongly interfered with the electrogenic lipid translocation. It is concluded that the electrogenicity is associated with a step in the ATPase reaction cycle directly involved in translocation of the lipid. These measurements also showed that no charged substrate is being countertransported, thereby distinguishing the P4-ATPase from P2-ATPases.
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21
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Zhang S, Liu W, Yang Y, Sun K, Li S, Xu H, Yang M, Zhang L, Zhu X. TMEM30A deficiency in endothelial cells impairs cell proliferation and angiogenesis. J Cell Sci 2019; 132:jcs.225052. [PMID: 30814335 DOI: 10.1242/jcs.225052] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 02/19/2019] [Indexed: 12/23/2022] Open
Abstract
Phosphatidylserine (PS) asymmetry in the eukaryotic cell membrane is maintained by a group of proteins belonging to the P4-ATPase family, namely, PS flippases. The folding and transporting of P4-ATPases to their cellular destination requires a β-subunit member of the TMEM30 protein family. Loss of Tmem30a has been shown to cause multiple disease conditions. However, its roles in vascular development have not been elucidated. Here, we show that TMEM30A plays critical roles in retinal vascular angiogenesis, which is a fundamental process in vascular development. Our data indicate that knockdown of TMEM30A in primary human retinal endothelial cells led to reduced tube formation. In mice, endothelial cell (EC)-specific deletion of Tmem30a led to retarded retinal vascular development with a hyperpruned vascular network as well as blunted-end, aneurysm-like tip ECs with fewer filopodia at the vascular front and a reduced number of tip cells. Deletion of Tmem30a also impaired vessel barrier integrity. Mechanistically, deletion of TMEM30A caused reduced EC proliferation by inhibiting VEGF-induced signaling. Our findings reveal essential roles of TMEM30A in angiogenesis, providing a potential therapeutic target.
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Affiliation(s)
- Shanshan Zhang
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China.,Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China
| | - Wenjing Liu
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China
| | - Yeming Yang
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China
| | - Kuanxiang Sun
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China.,Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China
| | - Shujin Li
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China
| | - Huijuan Xu
- Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China
| | - Mu Yang
- Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China
| | - Lin Zhang
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China .,Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China
| | - Xianjun Zhu
- Institute of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054, China .,Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, 610072, China; Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, Sichuan, China.,Department of Ophthalmology, Shangqiu First People's Hospital, Shangqiu, Henan, 476000, China.,Institute of Laboratory Animal Sciences, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610212, China
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22
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Yang Y, Liu W, Sun K, Jiang L, Zhu X. Tmem30a deficiency leads to retinal rod bipolar cell degeneration. J Neurochem 2019; 148:400-412. [PMID: 30548540 DOI: 10.1111/jnc.14643] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 11/09/2018] [Accepted: 12/02/2018] [Indexed: 12/13/2022]
Abstract
Phospholipids are asymmetrically distributed across the mammalian plasma membrane, with phosphatidylserine (PS) and phosphatidylethanolamine concentrated in the cytoplasmic leaflet of the membrane bilayer and phosphatidylcholine in the exoplasmic leaflet. This asymmetric distribution is dependent on a group of P4 ATPases called PS flippases. The proper transport and function of PS flippases require a β-subunit transmembrane protein 30A (TMEM30A). Disruption of PS flippases leads to several human diseases. Tmem30a is essential for photoreceptor survival. However, the roles of Tmem30a in the retinal rod bipolar cells (RBC) remain elusive. To investigate the role of Tmem30a in the RBCs, we generated a RBC-specific Tmem30a knockout (cKO) mouse model using PCP2-Cre line. The Tmem30a cKO mice exhibited defect in RBC function and progressive RBC death. PKCα staining of retinal cryosections from cKO mice revealed a remarkable dendritic sprouting of rod bipolar cells during the early degenerative process. Immunostaining analysis of PSD95 and mGluT6 expression demonstrated that rod bipolar cells in Tmem30a cKO retinas exhibited aberrant dendritic sprouting as a result of impaired synaptic efficacy, which implied a crucial role for Tmem30a in synaptic transmission in the retina. In addition, loss of Tmem30a led to reactive gliosis with increased expression of glial fibrillary acidic protein and CD68. TUNEL staining suggested that apoptotic cell death occurred in the retinal inner nuclear layer (INL). Our data show that loss of Tmem30a in RBCs results in dendritic sprouting of rod bipolar cells, increased astrogliosis and RBC death. Taken together, our studies demonstrate an essential role for Tmem30a in the retinal bipolar cells. Cover Image for this issue: doi: 10.1111/jnc.14492.
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Affiliation(s)
- Yeming Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Wenjing Liu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Kuanxiang Sun
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Li Jiang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, China
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.,Institute of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China.,Department of Ophthalmology, Shangqiu First Municipal People's Hospital, Shangqiu, Henan, China.,Institute of Chengdu Biology, Chinese Academy of Sciences, Chengdu, China.,Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, China
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23
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Disruption of Tmem30a results in cerebellar ataxia and degeneration of Purkinje cells. Cell Death Dis 2018; 9:899. [PMID: 30185775 PMCID: PMC6125289 DOI: 10.1038/s41419-018-0938-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 07/30/2018] [Accepted: 08/02/2018] [Indexed: 12/11/2022]
Abstract
Phospholipids are asymmetrically distributed across mammalian plasma membrane with phosphatidylserine (PS) and phosphatidylethanolamine concentrated in the cytoplasmic leaflet of the membrane bilayer. This asymmetric distribution is dependent on a group of P4-ATPases named PS flippases. The proper transport and function of PS flippases require a β-subunit transmembrane protein 30 A (TMEM30A). Disruption of PS flippases led to several human diseases. However, the roles of TMEM30A in the central nervous system remain elusive. To investigate the role of Tmem30a in the cerebellum, we developed a Tmem30a Purkinje cell (PC)-specific knockout (KO) mouse model. The Tmem30a KO mice displayed early-onset ataxia and progressive PC death. Deficiency in Tmem30a led to an increased expression of Glial fibrillary acidic protein and astrogliosis in regions with PC loss. Elevated C/EBP homologous protein and BiP expression levels indicated the presence of endoplasmic reticulum stress in the PCs prior to visible cell loss. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) analysis suggested that apoptotic cell death occurred in the cerebellum. Our data demonstrate that loss of Tmem30a in PCs results in protein folding and transport defects, a substantial decrease in dendritic spine density, increased astrogliosis and PC death. Taken together, our data demonstrate an essential role of Tmem30a in the cerebellum PCs.
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24
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Wang J, Molday LL, Hii T, Coleman JA, Wen T, Andersen JP, Molday RS. Proteomic Analysis and Functional Characterization of P4-ATPase Phospholipid Flippases from Murine Tissues. Sci Rep 2018; 8:10795. [PMID: 30018401 PMCID: PMC6050252 DOI: 10.1038/s41598-018-29108-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 07/05/2018] [Indexed: 01/31/2023] Open
Abstract
P4-ATPases are a subfamily of P-type ATPases that flip phospholipids across membranes to generate lipid asymmetry, a property vital to many cellular processes. Mutations in several P4-ATPases have been linked to severe neurodegenerative and metabolic disorders. Most P4-ATPases associate with one of three accessory subunit isoforms known as CDC50A (TMEM30A), CDC50B (TMEM30B), and CDC50C (TMEM30C). To identify P4-ATPases that associate with CDC50A, in vivo, and determine their tissue distribution, we isolated P4-ATPases-CDC50A complexes from retina, brain, liver, testes, and kidney on a CDC50A immunoaffinity column and identified and quantified P4-ATPases from their tryptic peptides by mass spectrometry. Of the 12 P4-ATPase that associate with CDC50 subunits, 10 P4-ATPases were detected. Four P4-ATPases (ATP8A1, ATP11A, ATP11B, ATP11C) were present in all five tissues. ATP10D was found in low amounts in liver, brain, testes, and kidney, and ATP8A2 was present in significant amounts in retina, brain, and testes. ATP8B1 was detected only in liver, ATP8B3 and ATP10A only in testes, and ATP8B2 primarily in brain. We also show that ATP11A, ATP11B and ATP11C, like ATP8A1 and ATP8A2, selectively flip phosphatidylserine and phosphatidylethanolamine across membranes. These studies provide new insight into the tissue distribution, relative abundance, subunit interactions and substrate specificity of P4-ATPase-CDC50A complexes.
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Affiliation(s)
- Jiao Wang
- Department of Biochemistry and Molecular Biology, Centre for Macular Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
- Laboratory of Molecular Neural Biology, Institute of Systems Biology, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Laurie L Molday
- Department of Biochemistry and Molecular Biology, Centre for Macular Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Theresa Hii
- Department of Biochemistry and Molecular Biology, Centre for Macular Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Jonathan A Coleman
- Department of Biochemistry and Molecular Biology, Centre for Macular Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Tieqiao Wen
- Laboratory of Molecular Neural Biology, Institute of Systems Biology, School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Jens P Andersen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, Centre for Macular Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada.
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25
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McMillan HJ, Telegrafi A, Singleton A, Cho MT, Lelli D, Lynn FC, Griffin J, Asamoah A, Rinne T, Erasmus CE, Koolen DA, Haaxma CA, Keren B, Doummar D, Mignot C, Thompson I, Velsher L, Dehghani M, Vahidi Mehrjardi MY, Maroofian R, Tchan M, Simons C, Christodoulou J, Martín-Hernández E, Guillen Sacoto MJ, Henderson LB, McLaughlin H, Molday LL, Molday RS, Yoon G. Recessive mutations in ATP8A2 cause severe hypotonia, cognitive impairment, hyperkinetic movement disorders and progressive optic atrophy. Orphanet J Rare Dis 2018; 13:86. [PMID: 30012219 PMCID: PMC6048855 DOI: 10.1186/s13023-018-0825-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 05/15/2018] [Indexed: 12/30/2022] Open
Abstract
Background ATP8A2 mutations have recently been described in several patients with severe, early-onset hypotonia and cognitive impairment. The aim of our study was to characterize the clinical phenotype of patients with ATP8A2 mutations. Methods An observational study was conducted at multiple diagnostic centres. Clinical data is presented from 9 unreported and 2 previously reported patients with ATP8A2 mutations. We compare their features with 3 additional patients that have been previously reported in the medical literature. Results Eleven patients with biallelic ATP8A2 mutations were identified, with a mean age of 9.4 years (range 2.5–28 years). All patients with ATP8A2 mutations (100%) demonstrated developmental delay, severe hypotonia and movement disorders, specifically chorea or choreoathetosis (100%), dystonia (27%) and facial dyskinesia (18%). Optic atrophy was observed in 78% of patients for whom funduscopic examination was performed. Symptom onset in all (100%) was noted before 6 months of age, with 70% having symptoms noted at birth. Feeding difficulties were common (91%) although most patients were able to tolerate pureed or thickened feeds, and 3 patients required gastrostomy tube insertion. MRI of the brain was normal in 50% of the patients. A smaller proportion was noted to have mild cortical atrophy (30%), delayed myelination (20%) and/or hypoplastic optic nerves (20%). Functional studies were performed on differentiated induced pluripotent cells from one child, which confirmed a decrease in ATP8A2 expression compared to control cells. Conclusions ATP8A2 gene mutations have emerged as the cause of a novel neurological phenotype characterized by global developmental delays, severe hypotonia and hyperkinetic movement disorders, the latter being an important distinguishing feature. Optic atrophy is common and may only become apparent in the first few years of life, necessitating repeat ophthalmologic evaluation in older children. Early recognition of the cardinal features of this condition will facilitate diagnosis of this complex neurologic disorder. Electronic supplementary material The online version of this article (10.1186/s13023-018-0825-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hugh J McMillan
- Division of Neurology, Department of Pediatrics, Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada
| | | | | | | | - Daniel Lelli
- Division of Neurology, Department of Medicine, The Ottawa Hospital, University of Ottawa, Ottawa, ON, Canada
| | - Francis C Lynn
- Diabetes Research Program, Child and Family Research Institute, Vancouver, BC, Canada.,Department of Surgery and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Julie Griffin
- Weisskopf Child Evaluation Center, Department of Pediatrics, School of Medicine, University of Louisville, Louisville, KY, USA
| | - Alexander Asamoah
- Weisskopf Child Evaluation Center, Department of Pediatrics, School of Medicine, University of Louisville, Louisville, KY, USA
| | - Tuula Rinne
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Corrie E Erasmus
- Department of Neurology, Donders Center of Neuroscience, Radboud University Medical Center, Nijmegen, The Netherlands
| | - David A Koolen
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Charlotte A Haaxma
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Boris Keren
- Assistance Publique Hôpitaux de Paris, Département de Génétique, Groupe Hospitalier, Pitié-Salpêtrière, Paris, France
| | - Diane Doummar
- Service de Neuropédiatrie, Hôpital Armand-Trousseau, Paris, France
| | - Cyril Mignot
- Assistance Publique Hôpitaux de Paris, Département de Génétique, Groupe Hospitalier, Pitié-Salpêtrière, Paris, France.,Centre de Référence Déficiences Intellectuelles de Causes Rares, GH Pitié Salpêtrière, Paris, France.,Groupe de Recherche Clinique UPMC Déficience Intellectuelle de Causes Rares et Autisme GH Pitié-Salpêtrière, Paris, France
| | - Islay Thompson
- Genetics Program, North York General Hospital, Toronto, ON, Canada
| | - Lea Velsher
- Genetics Program, North York General Hospital, Toronto, ON, Canada
| | - Mohammadreza Dehghani
- Medical Genetics Research Centre, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.,Reproductive Sciences Institute, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Mohammad Yahya Vahidi Mehrjardi
- Reproductive Sciences Institute, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.,Diabetes Research Centre, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Reza Maroofian
- Human Genetics Research Centre, Molecular and Clinical Sciences Institute, St George's University of London, London, UK
| | - Michel Tchan
- Department of Genetic Medicine, Westmead Hospital, Westmead, NSW, Australia.,Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Cas Simons
- Institute for Molecular Bioscience, University of Queensland, St Lucia, QLD, Australia
| | - John Christodoulou
- Neurodevelopmental Genomics Research Group, Murdoch Childrens Research Institute and Department of Paediatrics, Melbourne Medical School, University of Melbourne, Melbourne, VIC, Australia
| | - Elena Martín-Hernández
- Unidad de Enfermedades Mitocondriales-Metabólicas Hereditarias, Servicio de Pediatría Hospital Universitario 12 de Octubre, Universidad Complutense de Madrid, Madrid, Spain
| | | | | | | | - Laurie L Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.,Department of Ophthalmology and Visual Sciences, Centre for Macular Research, University of British Columbia, Vancouver, BC, Canada
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.,Department of Ophthalmology and Visual Sciences, Centre for Macular Research, University of British Columbia, Vancouver, BC, Canada
| | - Grace Yoon
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, M5G 1X8, Canada. .,Division of Neurology, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
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26
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Li N, Yang Y, Liang C, Qiu Q, Pan C, Li M, Yang S, Chen L, Zhu X, Hu Y. Tmem30a Plays Critical Roles in Ensuring the Survival of Hematopoietic Cells and Leukemia Cells in Mice. THE AMERICAN JOURNAL OF PATHOLOGY 2018; 188:1457-1468. [PMID: 29574182 DOI: 10.1016/j.ajpath.2018.02.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 02/03/2018] [Accepted: 02/27/2018] [Indexed: 02/05/2023]
Abstract
The fundamental structure of eukaryotic cell plasma membrane is the phospholipid bilayer, which contains four major phospholipids. These phospholipids are asymmetrically distributed between the outer and inner leaflets. P4-ATPase flippase complexes play essential roles in ensuring this asymmetry. We found that conditional deletion of Tmem30a, the β subunit of P4-ATPase flippase complex, caused pancytopenia in mice. Tmem30a deficiency resulted in depletion of lineage-committed blood cells in the peripheral blood, spleen, and bone marrow. Ablation of Tmem30a also caused the depletion of hematopoietic stem cells (HSCs). HSC RNA sequencing results revealed that multiple biological processes and signal pathways were involved in the event, including mammalian target of rapamycin signaling, genes for HSC stemness, and genes responding to interferons. Our results also revealed that targeting Tmem30a signaling had therapeutic utility in BCR/ABL1-induced chronic myeloid leukemia.
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Affiliation(s)
- Ning Li
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yeming Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Cailing Liang
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Qiang Qiu
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Cong Pan
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Mengyuan Li
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Shengyong Yang
- State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Lijuan Chen
- State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, China; Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China; Chengdu Institute of Biology, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China.
| | - Yiguo Hu
- Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, China; State Key Laboratory of Biotherapy & Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
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Alsahli S, Alrifai MT, Al Tala S, Mutairi FA, Alfadhel M. Further Delineation of the Clinical Phenotype of Cerebellar Ataxia, Mental Retardation, and Disequilibrium Syndrome Type 4. J Cent Nerv Syst Dis 2018. [PMID: 29531481 PMCID: PMC5843099 DOI: 10.1177/1179573518759682] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background Cerebellar ataxia, mental retardation, and disequilibrium syndrome (CAMRQ) is a heterogeneous group of genetic disorders that have been grouped by shared clinical features; all of these features are transmitted via an autosomal recessive mechanism. Four variants of this syndrome have been identified so far, and each one differs in terms of both clinical and genotypical features. CAMRQ4 is a rare genetic disorder characterized by mental retardation, ataxia or an inability to walk, dysarthria and, in some patients, quadrupedal gait. Methods We investigated three Saudi families with CAMRQ4. Blood samples were collected from the affected patients, their parents, and healthy siblings. DNA was extracted from whole blood, and whole-exome sequencing was performed. Findings were confirmed by segregation analysis, which was performed on other family members. Results Thus far, 17 patients have been affected by CAMRQ4. Genetic analysis of all patients, including our current patients, showed a mutation in the aminophospholipid transporter, class I, type 8A, member 2 gene (ATP8A2). A series of common phenotypical features have been reported in these patients, with few exceptions. Ataxia, mental retardation, and hypotonia were present in all patients, consanguinity in 90% and abnormal movements in 50%. Moreover, 40% achieved ambulation at least once in their lifetime, 40% had microcephaly, whereas 30% were mute. Magnetic resonance imaging (MRI) of the brain was normal in 60% of patients. Conclusions We described the largest cohort of patients with CAMRQ4 syndrome and identified three novel mutations. CAMRQ4 syndrome should be suspected in patients presenting with ataxia, intellectual disability, hypotonia, microcephaly, choreoathetoid movements, ophthalmoplegia, and global developmental delay, even if brain MRI appears normal.
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Affiliation(s)
- Saud Alsahli
- King Abdullah International Medical Research Center (KAIMRC), King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (MNGHA), Riyadh, Saudi Arabia
| | - Muhammad Talal Alrifai
- King Abdullah International Medical Research Center (KAIMRC), King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (MNGHA), Riyadh, Saudi Arabia.,King Abdullah International Medical Research Center (KAIMRC), Division of Neurology, Department of Pediatrics, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (MNGHA), Riyadh, Saudi Arabia
| | - Saeed Al Tala
- Division of Genetics, Department of Pediatrics, Armed Forces Hospital, Khamis Mushayt, Saudi Arabia
| | - Fuad Al Mutairi
- King Abdullah International Medical Research Center (KAIMRC), King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (MNGHA), Riyadh, Saudi Arabia.,King Abdullah International Medical Research Center (KAIMRC), Division of Genetics, Department of Pediatrics, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (MNGHA), Riyadh, Saudi Arabia
| | - Majid Alfadhel
- King Abdullah International Medical Research Center (KAIMRC), King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (MNGHA), Riyadh, Saudi Arabia.,King Abdullah International Medical Research Center (KAIMRC), Division of Genetics, Department of Pediatrics, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (MNGHA), Riyadh, Saudi Arabia
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28
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Bertini E, Zanni G, Boltshauser E. Nonprogressive congenital ataxias. HANDBOOK OF CLINICAL NEUROLOGY 2018; 155:91-103. [PMID: 29891079 DOI: 10.1016/b978-0-444-64189-2.00006-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The terminology of nonprogressive congenital ataxia (NPCA) refers to a clinically and genetically heterogeneous group of disorders characterized by congenital or early-onset ataxia, but no progression or even improvement on follow-up. Ataxia is preceded by muscular hypotonia and delayed motor (and usually language) milestones. We exclude children with prenatal, perinatal, and postnatal acquired diseases, malformations other than cerebellar hypoplasia, and defined syndromic disorders. Patients with NPCA have a high prevalence of cognitive and language impairments, in addition to increased occurrence of seizures, ocular signs (nystagmus, strabismus), behavior changes, and microcephaly. Neuroimaging is variable, ranging from normal cerebellar anatomy to reduced cerebellar volume (hypoplasia in the proper sense), and enlarged interfolial spaces, potentially mimicking atrophy. The latter appearance is often called "hypoplasia" as well, in view of the static clinical course. Some patients had progressive enlargement of cerebellar fissures, but a nonprogressive course. There is no imaging-clinical-genetic correlation. Dominant, recessive, and X-linked inheritance is documented for NPCA. Here, we focus on the still rather short list of dominant and recessive genes associated with NPCA, identified in the last few years. With future advances in genetics, we expect a rapid expansion of knowledge in this field.
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Affiliation(s)
- Enrico Bertini
- Unit of Neuromuscular and Neurodegenerative Disorders, Bambino Gesu' Children's Research Hospital, Rome, Italy.
| | - Ginevra Zanni
- Unit of Neuromuscular and Neurodegenerative Disorders, Bambino Gesu' Children's Research Hospital, Rome, Italy
| | - Eugen Boltshauser
- Department of Pediatric Neurology, University Children's Hospital, University of Zurich, Zurich, Switzerland
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29
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Zhang L, Yang Y, Li S, Zhang S, Zhu X, Tai Z, Yang M, Liu Y, Guo X, Chen B, Jiang Z, Lu F, Zhu X. Loss of Tmem30a leads to photoreceptor degeneration. Sci Rep 2017; 7:9296. [PMID: 28839191 PMCID: PMC5571223 DOI: 10.1038/s41598-017-09506-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 07/26/2017] [Indexed: 12/16/2022] Open
Abstract
Phosphatidylserine (PS) is asymmetrically distributed between the outer and inner leaflets of the plasma membrane in eukaryotic cells. PS asymmetry on the plasma membrane depends on the activities of P4-ATPases, and disruption of PS distribution can lead to various disease conditions. Folding and transporting of P4-ATPases to their cellular destination requires the β subunit TMEM30A proteins. However, the in vivo functions of Tmem30a remain unknown. To this end, we generated retinal-specific Tmem30a-knockout mice to investigate its roles in vivo for the first time. Our data demonstrated that loss of Tmem30a in mouse cone cells leads to mislocalization of cone opsin, loss of photopic electroretinogram (ERG) responses and loss of cone cells. Mechanistically, Tmem30a-mutant mouse embryonic fibroblasts (MEFs) exhibited diminished PS flippase activity and increased exposure of PS on the cell surface. The broad loss of Tmem30a in adult mice led to a reduced scotopic photoresponse, mislocalization of ATP8A2 to the inner segment and cell body, and increased apoptosis in the retina. Our data demonstrated novel essential roles of Tmem30a in the retina.
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Affiliation(s)
- Lin Zhang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Yeming Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Shujin Li
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Chengdu Institute of Biology, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
| | - Shanshan Zhang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Xiong Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Zhengfu Tai
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Chengdu Institute of Biology, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
| | - Mu Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Chengdu Institute of Biology, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China
| | - Yuqing Liu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Xinzheng Guo
- Department of Ophthalmology, Yale University School of Medicine, New Haven, CT, USA
| | - Bo Chen
- Department of Ophthalmology, Yale University School of Medicine, New Haven, CT, USA
| | - Zhilin Jiang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China
| | - Fang Lu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China. .,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China.
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Hospital of the University of Electronic Science and Technology of China and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China. .,Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, 610072, China. .,Institute of Laboratory Animal Sciences, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, China. .,Chengdu Institute of Biology, Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, Sichuan, China.
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30
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Chen J, Wang Z, Zhang S, Ai Q, Chu S, Chen NH. Possible target-related proteins of stress-resistant rats suggested by label-free proteomic analysis. RSC Adv 2017. [DOI: 10.1039/c7ra04212d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Stress plays a crucial role in the development of major depressive disorder, but the molecular mechanism underlying the susceptibility vs. resilience to stress remains unclear.
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Affiliation(s)
- Jiao Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines
- Institute of Materia Medica & Neuroscience Center
- Chinese Academy of Medical Sciences and Peking Union Medical College
- Beijing 100050
- China
| | - Zhenzhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines
- Institute of Materia Medica & Neuroscience Center
- Chinese Academy of Medical Sciences and Peking Union Medical College
- Beijing 100050
- China
| | - Shuai Zhang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines
- Institute of Materia Medica & Neuroscience Center
- Chinese Academy of Medical Sciences and Peking Union Medical College
- Beijing 100050
- China
| | - Qidi Ai
- Hunan University of Chinese Medicine
- Changsha
- China
| | - Shifeng Chu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines
- Institute of Materia Medica & Neuroscience Center
- Chinese Academy of Medical Sciences and Peking Union Medical College
- Beijing 100050
- China
| | - Nai-hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines
- Institute of Materia Medica & Neuroscience Center
- Chinese Academy of Medical Sciences and Peking Union Medical College
- Beijing 100050
- China
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31
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New ATP8A2 gene mutations associated with a novel syndrome: encephalopathy, intellectual disability, severe hypotonia, chorea and optic atrophy. Neurogenetics 2016; 17:259-263. [PMID: 27679995 DOI: 10.1007/s10048-016-0496-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 09/14/2016] [Accepted: 09/16/2016] [Indexed: 01/14/2023]
Abstract
We report the clinical and biochemical findings from two unrelated patients who presented with a novel syndrome: encephalopathy, intellectual disability, severe hypotonia, chorea and optic atrophy. Whole exome sequencing (WES) uncovered a homozygous mutation in the ATP8A2 gene (NM_016529:c.1287G > T, p.K429N) in one patient and compound heterozygous mutations (c.1630G > C, p.A544P and c.1873C > T, p.R625W) in the other. Only one haploinsufficiency case and a family with a homozygous mutation in ATP8A2 gene (c.1128C > G, p.I376M) have been described so far, with phenotypes that differed slightly from the patients described herein. In conclusion, our data expand both the genetic and phenotypic spectrum associated with ATP8A2 gene mutations.
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Directed evolution of a sphingomyelin flippase reveals mechanism of substrate backbone discrimination by a P4-ATPase. Proc Natl Acad Sci U S A 2016; 113:E4460-6. [PMID: 27432949 DOI: 10.1073/pnas.1525730113] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phospholipid flippases in the type IV P-type ATPase (P4-ATPases) family establish membrane asymmetry and play critical roles in vesicular transport, cell polarity, signal transduction, and neurologic development. All characterized P4-ATPases flip glycerophospholipids across the bilayer to the cytosolic leaflet of the membrane, but how these enzymes distinguish glycerophospholipids from sphingolipids is not known. We used a directed evolution approach to examine the molecular mechanisms through which P4-ATPases discriminate substrate backbone. A mutagenesis screen in the yeast Saccharomyces cerevisiae has identified several gain-of-function mutations in the P4-ATPase Dnf1 that facilitate the transport of a novel lipid substrate, sphingomyelin. We found that a highly conserved asparagine (N220) in the first transmembrane segment is a key enforcer of glycerophospholipid selection, and specific substitutions at this site allow transport of sphingomyelin.
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33
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Hertz DL, Owzar K, Lessans S, Wing C, Jiang C, Kelly WK, Patel J, Halabi S, Furukawa Y, Wheeler HE, Sibley AB, Lassiter C, Weisman L, Watson D, Krens SD, Mulkey F, Renn CL, Small EJ, Febbo PG, Shterev I, Kroetz DL, Friedman PN, Mahoney JF, Carducci MA, Kelley MJ, Nakamura Y, Kubo M, Dorsey SG, Dolan ME, Morris MJ, Ratain MJ, McLeod HL. Pharmacogenetic Discovery in CALGB (Alliance) 90401 and Mechanistic Validation of a VAC14 Polymorphism that Increases Risk of Docetaxel-Induced Neuropathy. Clin Cancer Res 2016; 22:4890-4900. [PMID: 27143689 DOI: 10.1158/1078-0432.ccr-15-2823] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 04/04/2016] [Indexed: 12/13/2022]
Abstract
PURPOSE Discovery of SNPs that predict a patient's risk of docetaxel-induced neuropathy would enable treatment individualization to maximize efficacy and avoid unnecessary toxicity. The objectives of this analysis were to discover SNPs associated with docetaxel-induced neuropathy and mechanistically validate these associations in preclinical models of drug-induced neuropathy. EXPERIMENTAL DESIGN A genome-wide association study was conducted in metastatic castrate-resistant prostate cancer patients treated with docetaxel, prednisone and randomized to bevacizumab or placebo on CALGB 90401. SNPs were genotyped on the Illumina HumanHap610-Quad platform followed by rigorous quality control. The inference was conducted on the cumulative dose at occurrence of grade 3+ sensory neuropathy using a cause-specific hazard model that accounted for early treatment discontinuation. Genes with SNPs significantly associated with neuropathy were knocked down in cellular and mouse models of drug-induced neuropathy. RESULTS A total of 498,081 SNPs were analyzed in 623 Caucasian patients, 50 (8%) of whom experienced grade 3+ neuropathy. The 1,000 SNPs most associated with neuropathy clustered in relevant pathways including neuropathic pain and axonal guidance. An SNP in VAC14 (rs875858) surpassed genome-wide significance (P = 2.12 × 10-8, adjusted P = 5.88 × 10-7). siRNA knockdown of VAC14 in stem cell-derived peripheral neuronal cells increased docetaxel sensitivity as measured by decreased neurite processes (P = 0.0015) and branches (P < 0.0001). Prior to docetaxel treatment, VAC14 heterozygous mice had greater nociceptive sensitivity than wild-type litter mate controls (P = 0.001). CONCLUSIONS VAC14 should be prioritized for further validation of its potential role as a predictor of docetaxel-induced neuropathy and biomarker for treatment individualization. Clin Cancer Res; 22(19); 4890-900. ©2016 AACR.
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Affiliation(s)
- Daniel L Hertz
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, Michigan. UNC Institute for Pharmacogenomics and Individualized Therapy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Kouros Owzar
- Duke Cancer Institute, Durham, North Carolina. Alliance Statistics and Data Center, Duke University, Durham, North Carolina
| | - Sherrie Lessans
- Department of Pain and Translational Symptom Science, University of Maryland School of Nursing, Baltimore, Maryland
| | - Claudia Wing
- Department of Medicine, University of Chicago, Chicago, Illinois
| | - Chen Jiang
- Alliance Statistics and Data Center, Duke University, Durham, North Carolina
| | | | - Jai Patel
- UNC Institute for Pharmacogenomics and Individualized Therapy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Levine Cancer Institute, Carolinas HealthCare System, Charlotte, North Carolina
| | - Susan Halabi
- Duke Cancer Institute, Durham, North Carolina. Alliance Statistics and Data Center, Duke University, Durham, North Carolina
| | - Yoichi Furukawa
- Division of Clinical Genome Research, Advanced Clinical Research Center, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | | | | | - Cameron Lassiter
- Department of Pain and Translational Symptom Science, University of Maryland School of Nursing, Baltimore, Maryland
| | - Lois Weisman
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan
| | - Dorothy Watson
- Alliance Statistics and Data Center, Duke University, Durham, North Carolina
| | - Stefanie D Krens
- UNC Institute for Pharmacogenomics and Individualized Therapy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Utrecht University, Faculty of Science, Department of Pharmaceutical Sciences, Utrecht, the Netherlands
| | - Flora Mulkey
- Alliance Statistics and Data Center, Duke University, Durham, North Carolina
| | - Cynthia L Renn
- Department of Pain and Translational Symptom Science, University of Maryland School of Nursing, Baltimore, Maryland
| | - Eric J Small
- Department of Medicine, UCSF, San Francisco, California
| | | | - Ivo Shterev
- Department of Biostatistics and Bioinformatics, Duke University, Durham, North Carolina
| | - Deanna L Kroetz
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California
| | - Paula N Friedman
- Department of Medicine, University of Chicago, Chicago, Illinois
| | - John F Mahoney
- Levine Cancer Institute, Carolinas HealthCare System, Charlotte, North Carolina
| | - Michael A Carducci
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, Maryland
| | - Michael J Kelley
- Durham VA Medical Center, Duke University Medical Center, Durham, North Carolina
| | - Yusuke Nakamura
- Department of Medicine, University of Chicago, Chicago, Illinois. Division of Clinical Genome Research, Advanced Clinical Research Center, Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Michiaki Kubo
- Lab for Genotyping Development, Riken Center for Integrative Medical Sciences, Kanagawa, Japan
| | - Susan G Dorsey
- Department of Pain and Translational Symptom Science, University of Maryland School of Nursing, Baltimore, Maryland
| | - M Eileen Dolan
- Department of Medicine, University of Chicago, Chicago, Illinois
| | | | - Mark J Ratain
- Department of Medicine, University of Chicago, Chicago, Illinois
| | - Howard L McLeod
- UNC Institute for Pharmacogenomics and Individualized Therapy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Personalized Medicine Institute, Moffitt Cancer Center, Tampa, Florida.
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Andersen JP, Vestergaard AL, Mikkelsen SA, Mogensen LS, Chalat M, Molday RS. P4-ATPases as Phospholipid Flippases-Structure, Function, and Enigmas. Front Physiol 2016; 7:275. [PMID: 27458383 PMCID: PMC4937031 DOI: 10.3389/fphys.2016.00275] [Citation(s) in RCA: 205] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 06/20/2016] [Indexed: 01/26/2023] Open
Abstract
P4-ATPases comprise a family of P-type ATPases that actively transport or flip phospholipids across cell membranes. This generates and maintains membrane lipid asymmetry, a property essential for a wide variety of cellular processes such as vesicle budding and trafficking, cell signaling, blood coagulation, apoptosis, bile and cholesterol homeostasis, and neuronal cell survival. Some P4-ATPases transport phosphatidylserine and phosphatidylethanolamine across the plasma membrane or intracellular membranes whereas other P4-ATPases are specific for phosphatidylcholine. The importance of P4-ATPases is highlighted by the finding that genetic defects in two P4-ATPases ATP8A2 and ATP8B1 are associated with severe human disorders. Recent studies have provided insight into how P4-ATPases translocate phospholipids across membranes. P4-ATPases form a phosphorylated intermediate at the aspartate of the P-type ATPase signature sequence, and dephosphorylation is activated by the lipid substrate being flipped from the exoplasmic to the cytoplasmic leaflet similar to the activation of dephosphorylation of Na(+)/K(+)-ATPase by exoplasmic K(+). How the phospholipid is translocated can be understood in terms of a peripheral hydrophobic gate pathway between transmembrane helices M1, M3, M4, and M6. This pathway, which partially overlaps with the suggested pathway for migration of Ca(2+) in the opposite direction in the Ca(2+)-ATPase, is wider than the latter, thereby accommodating the phospholipid head group. The head group is propelled along against its concentration gradient with the hydrocarbon chains projecting out into the lipid phase by movement of an isoleucine located at the position corresponding to an ion binding glutamate in the Ca(2+)- and Na(+)/K(+)-ATPases. Hence, the P4-ATPase mechanism is quite similar to the mechanism of these ion pumps, where the glutamate translocates the ions by moving like a pump rod. The accessory subunit CDC50 may be located in close association with the exoplasmic entrance of the suggested pathway, and possibly promotes the binding of the lipid substrate. This review focuses on properties of mammalian and yeast P4-ATPases for which most mechanistic insight is available. However, the structure, function and enigmas associated with mammalian and yeast P4-ATPases most likely extend to P4-ATPases of plants and other organisms.
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Affiliation(s)
| | | | | | | | - Madhavan Chalat
- Department of Biochemistry and Molecular Biology, University of British ColumbiaVancouver, BC, Canada
| | - Robert S. Molday
- Department of Biochemistry and Molecular Biology, University of British ColumbiaVancouver, BC, Canada
- *Correspondence: Robert S. Molday
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Lee S, Uchida Y, Wang J, Matsudaira T, Nakagawa T, Kishimoto T, Mukai K, Inaba T, Kobayashi T, Molday RS, Taguchi T, Arai H. Transport through recycling endosomes requires EHD1 recruitment by a phosphatidylserine translocase. EMBO J 2015; 34:669-88. [PMID: 25595798 PMCID: PMC4365035 DOI: 10.15252/embj.201489703] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
P4-ATPases translocate aminophospholipids, such as phosphatidylserine (PS), to the cytosolic leaflet of membranes. PS is highly enriched in recycling endosomes (REs) and is essential for endosomal membrane traffic. Here, we show that PS flipping by an RE-localized P4-ATPase is required for the recruitment of the membrane fission protein EHD1. Depletion of ATP8A1 impaired the asymmetric transbilayer distribution of PS in REs, dissociated EHD1 from REs, and generated aberrant endosomal tubules that appear resistant to fission. EHD1 did not show membrane localization in cells defective in PS synthesis. ATP8A2, a tissue-specific ATP8A1 paralogue, is associated with a neurodegenerative disease (CAMRQ). ATP8A2, but not the disease-causative ATP8A2 mutant, rescued the endosomal defects in ATP8A1-depleted cells. Primary neurons from Atp8a2-/- mice showed a reduced level of transferrin receptors at the cell surface compared to Atp8a2+/+ mice. These findings demonstrate the role of P4-ATPase in membrane fission and give insight into the molecular basis of CAMRQ.
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Affiliation(s)
- Shoken Lee
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan
| | - Yasunori Uchida
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan
| | - Jiao Wang
- Departments of Biochemistry and Molecular Biology and Ophthalmology and Visual Sciences, Centre for Macular Research University of British Columbia, Vancouver, BC, Canada
| | - Tatsuyuki Matsudaira
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan
| | - Takatoshi Nakagawa
- Department of Pharmacology, Osaka Medical College, Takatsuki-city Osaka, Japan
| | | | - Kojiro Mukai
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan Lipid Biology Laboratory, RIKEN, Wako-shi Saitama, Japan
| | - Takehiko Inaba
- Lipid Biology Laboratory, RIKEN, Wako-shi Saitama, Japan
| | | | - Robert S Molday
- Departments of Biochemistry and Molecular Biology and Ophthalmology and Visual Sciences, Centre for Macular Research University of British Columbia, Vancouver, BC, Canada
| | - Tomohiko Taguchi
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan Pathological Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan
| | - Hiroyuki Arai
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan Pathological Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences University of Tokyo, Tokyo, Japan
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Ilmjärv S, Reimets R, Hundahl CA, Luuk H. Effect of light on global gene expression in the neuroglobin-deficient mouse retina. Biomed Rep 2014; 2:780-786. [PMID: 25279145 DOI: 10.3892/br.2014.364] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Accepted: 09/03/2014] [Indexed: 01/18/2023] Open
Abstract
Several previous studies have raised controversy over the functional role of neuroglobin (Ngb) in the retina. Certain studies indicate a significant impact of Ngb on retinal physiology, whereas others are conflicting. The present is an observational study that tested the effect of Ngb deficiency on gene expression in dark- and light-adapted mouse retinas. Large-scale gene expression profiling was performed using GeneChip® Mouse Exon 1.0 ST arrays and the results were compared to publicly available data sets. The lack of Ngb was found to have a minor effect on the light-induced retinal gene expression response. In addition, there was no increase in the expression of marker genes associated with hypoxia, endoplasmic reticulum-stress and oxidative stress in the Ngb-deficient retina. By contrast, several genes were identified that appeared to be differentially expressed between the genotypes when the effect of light was ignored. The present study indicates that Ngb deficiency does not lead to major alternations in light-dependent gene expression response, but leads to subtle systemic differences of a currently unknown functional significance.
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Affiliation(s)
- Sten Ilmjärv
- Department of Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu 50411, Estonia ; Quretec Ltd, University of Tartu, Tartu 50411, Estonia
| | - Riin Reimets
- Department of Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu 50411, Estonia ; The Centre for Disease Models and Biomedical Imaging, University of Tartu, Tartu 50411, Estonia
| | - Christian Ansgar Hundahl
- Department of Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu 50411, Estonia ; The Centre for Disease Models and Biomedical Imaging, University of Tartu, Tartu 50411, Estonia ; Department of Clinical Biochemistry, Bispebjerg Hospital, Copenhagen 2400, Denmark
| | - Hendrik Luuk
- Department of Physiology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu 50411, Estonia ; The Centre for Disease Models and Biomedical Imaging, University of Tartu, Tartu 50411, Estonia
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Yabas M, Coupland LA, Cromer D, Winterberg M, Teoh NC, D'Rozario J, Kirk K, Bröer S, Parish CR, Enders A. Mice deficient in the putative phospholipid flippase ATP11C exhibit altered erythrocyte shape, anemia, and reduced erythrocyte life span. J Biol Chem 2014; 289:19531-7. [PMID: 24898253 DOI: 10.1074/jbc.c114.570267] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Transmembrane lipid transporters are believed to establish and maintain phospholipid asymmetry in biological membranes; however, little is known about the in vivo function of the specific transporters involved. Here, we report that developing erythrocytes from mice lacking the putative phosphatidylserine flippase ATP11C showed a lower rate of PS translocation in vitro compared with erythrocytes from wild-type littermates. Furthermore, the mutant mice had an elevated percentage of phosphatidylserine-exposing mature erythrocytes in the periphery. Although erythrocyte development in ATP11C-deficient mice was normal, the mature erythrocytes had an abnormal shape (stomatocytosis), and the life span of mature erythrocytes was shortened relative to that in control littermates, resulting in anemia in the mutant mice. Thus, our findings uncover an essential role for ATP11C in erythrocyte morphology and survival and provide a new candidate for the rare inherited blood disorder stomatocytosis with uncompensated anemia.
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Affiliation(s)
- Mehmet Yabas
- From the Ramaciotti Immunization Genomics Laboratory and
| | - Lucy A Coupland
- Cancer and Vascular Biology Group, Department of Immunology, The John Curtin School of Medical Research, and the Clinical Haematology Unit, The Canberra Hospital, Canberra, Australian Capital Territory 2605, Australia
| | - Deborah Cromer
- the Complex Systems in Biology Group, Centre for Vascular Research, University of New South Wales, Kensington, New South Wales 2052, Australia, and
| | - Markus Winterberg
- the Division of Biomedical Science and Biochemistry, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Narci C Teoh
- the Liver Research Group, Australian National University Medical School at the Canberra Hospital, Canberra, Australian Capital Territory 2605, Australia
| | - James D'Rozario
- the Clinical Haematology Unit, The Canberra Hospital, Canberra, Australian Capital Territory 2605, Australia
| | - Kiaran Kirk
- the Division of Biomedical Science and Biochemistry, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Stefan Bröer
- the Division of Biomedical Science and Biochemistry, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Christopher R Parish
- Cancer and Vascular Biology Group, Department of Immunology, The John Curtin School of Medical Research, and
| | - Anselm Enders
- From the Ramaciotti Immunization Genomics Laboratory and
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Lipid flippase modulates olfactory receptor expression and odorant sensitivity in Drosophila. Proc Natl Acad Sci U S A 2014; 111:7831-6. [PMID: 24821794 DOI: 10.1073/pnas.1401938111] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In Drosophila melanogaster, the male-specific pheromone cVA (11-cis-vaccenyl acetate) functions as a sex-specific social cue. However, our understanding of the molecular mechanisms underlying cVA pheromone transduction and its regulation are incomplete. Using a genetic screen combined with an electrophysiological assay to monitor pheromone-evoked activity in the cVA-sensing Or67d neurons, we identified an olfactory sensitivity factor encoded by the dATP8B gene, the Drosophila homolog of mammalian ATP8B. dATP8B is expressed in all olfactory neurons that express Orco, the odorant receptor coreceptor, and the odorant responses in most Orco-expressing neurons are reduced. Or67d neurons are severely affected, with strongly impaired cVA-induced responses and lacking spontaneous spiking in the mutants. The dATP8B locus encodes a member of the P4-type ATPase family thought to flip aminophospholipids such as phosphatidylserine and phosphatidylethanolamine from one membrane leaflet to the other. dATP8B protein is concentrated in the cilia of olfactory neuron dendrites, the site of odorant transduction. Focusing on Or67d neuron function, we show that Or67d receptors are mislocalized in dATP8B mutants and that cVA responses can be restored to dATP8B mutants by misexpressing a wild-type dATP8B rescuing transgene, by expressing a vertebrate P4-type ATPase member in the pheromone-sensing neurons or by overexpressing Or67d receptor subunits. These findings reveal an unexpected role for lipid translocation in olfactory receptor expression and sensitivity to volatile odorants.
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Critical roles of isoleucine-364 and adjacent residues in a hydrophobic gate control of phospholipid transport by the mammalian P4-ATPase ATP8A2. Proc Natl Acad Sci U S A 2014; 111:E1334-43. [PMID: 24706822 DOI: 10.1073/pnas.1321165111] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
P4-ATPases (flippases) translocate specific phospholipids such as phosphatidylserine from the exoplasmic leaflet of the cell membrane to the cytosolic leaflet, upholding an essential membrane asymmetry. The mechanism of flipping this giant substrate has remained an enigma. We have investigated the importance of amino acid residues in transmembrane segment M4 of mammalian P4-ATPase ATP8A2 by mutagenesis. In the related ion pumps Na(+),K(+)-ATPase and Ca(2+)-ATPase, M4 moves during the enzyme cycle, carrying along the ion bound to a glutamate. In ATP8A2, the corresponding residue is an isoleucine, which recently was found mutated in patients with cerebellar ataxia, mental retardation, and dysequilibrium syndrome. Our analyses of the lipid substrate concentration dependence of the overall and partial reactions of the enzyme cycle in mutants indicate that, during the transport across the membrane, the phosphatidylserine head group passes near isoleucine-364 (I364) and that I364 is critical to the release of the transported lipid into the cytosolic leaflet. Another M4 residue, N359, is involved in recognition of the lipid substrate on the exoplasmic side. Our functional studies are supported by structural homology modeling and molecular dynamics simulations, suggesting that I364 and adjacent hydrophobic residues function as a hydrophobic gate that separates the entry and exit sites of the lipid and directs sequential formation and annihilation of water-filled cavities, thereby enabling transport of the hydrophilic phospholipid head group in a groove outlined by the transmembrane segments M1, M2, M4, and M6, with the hydrocarbon chains following passively, still in the membrane lipid phase.
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Bens S, Zichner T, Stütz AM, Caliebe A, Wagener R, Hoff K, Korbel JO, von Bismarck P, Siebert R. SPAG7 is a candidate gene for the periodic fever, aphthous stomatitis, pharyngitis and adenopathy (PFAPA) syndrome. Genes Immun 2014; 15:190-4. [PMID: 24452265 DOI: 10.1038/gene.2013.73] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Revised: 12/15/2013] [Accepted: 12/16/2013] [Indexed: 12/20/2022]
Abstract
Periodic fever, aphthous stomatitis, pharyngitis and adenopathy (PFAPA) syndrome is an auto-inflammatory disease for which a genetic basis has been postulated. Nevertheless, in contrast to the other periodic fever syndromes, no candidate genes have yet been identified. By cloning, following long insert size paired-end sequencing, of a de novo chromosomal translocation t(10;17)(q11.2;p13) in a patient with typical PFAPA syndrome lacking mutations in genes associated with other periodic fever syndromes we identified SPAG7 as a candidate gene for PFAPA. SPAG7 protein is expressed in tissues affected by PFAPA and has been functionally linked to antiviral and inflammatory responses. Haploinsufficiency of SPAG7 due to a microdeletion at the translocation breakpoint leading to loss of exons 2-7 from one allele was associated with PFAPA in the index. Sequence analyses of SPAG7 in additional patients with PFAPA point to genetic heterogeneity or alternative mechanisms of SPAG7 deregulation, such as somatic or epigenetic changes.
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Affiliation(s)
- S Bens
- Institute of Human Genetics, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Kiel, Germany
| | - T Zichner
- European Molecular Biology Laboratory (EMBL), Genome Biology Research Unit, Heidelberg, Germany
| | - A M Stütz
- European Molecular Biology Laboratory (EMBL), Genome Biology Research Unit, Heidelberg, Germany
| | - A Caliebe
- Institute of Human Genetics, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Kiel, Germany
| | - R Wagener
- Institute of Human Genetics, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Kiel, Germany
| | - K Hoff
- 1] Institute of Human Genetics, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Kiel, Germany [2] Department of Congenital Heart Disease and Pediatric Cardiology, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Kiel, Germany
| | - J O Korbel
- European Molecular Biology Laboratory (EMBL), Genome Biology Research Unit, Heidelberg, Germany
| | - P von Bismarck
- Department of Pediatrics, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Kiel, Germany
| | - R Siebert
- Institute of Human Genetics, Christian-Albrechts-University Kiel & University Hospital Schleswig-Holstein, Kiel, Germany
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Coleman JA, Zhu X, Djajadi HR, Molday LL, Smith RS, Libby RT, John SWM, Molday RS. Phospholipid flippase ATP8A2 is required for normal visual and auditory function and photoreceptor and spiral ganglion cell survival. J Cell Sci 2014; 127:1138-49. [PMID: 24413176 DOI: 10.1242/jcs.145052] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
ATP8A2 is a P4-ATPase that is highly expressed in the retina, brain, spinal cord and testes. In the retina, ATP8A2 is localized in photoreceptors where it uses ATP to transport phosphatidylserine (PS) and phosphatidylethanolamine (PE) from the exoplasmic to the cytoplasmic leaflet of membranes. Although mutations in ATP8A2 have been reported to cause mental retardation in humans and degeneration of spinal motor neurons in mice, the role of ATP8A2 in sensory systems has not been investigated. We have analyzed the retina and cochlea of ATP8A2-deficient mice to determine the role of ATP8A2 in visual and auditory systems. ATP8A2-deficient mice have shortened photoreceptor outer segments, a reduction in photoresponses and decreased photoreceptor viability. The ultrastructure and phagocytosis of the photoreceptor outer segment appeared normal, but the PS and PE compositions were altered and the rhodopsin content was decreased. The auditory brainstem response threshold was significantly higher and degeneration of spiral ganglion cells was apparent. Our studies indicate that ATP8A2 plays a crucial role in photoreceptor and spiral ganglion cell function and survival by maintaining phospholipid composition and contributing to vesicle trafficking.
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Affiliation(s)
- Jonathan A Coleman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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van der Mark VA, Elferink RPJO, Paulusma CC. P4 ATPases: flippases in health and disease. Int J Mol Sci 2013; 14:7897-922. [PMID: 23579954 PMCID: PMC3645723 DOI: 10.3390/ijms14047897] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 03/28/2013] [Accepted: 04/07/2013] [Indexed: 12/26/2022] Open
Abstract
P4 ATPases catalyze the translocation of phospholipids from the exoplasmic to the cytosolic leaflet of biological membranes, a process termed “lipid flipping”. Accumulating evidence obtained in lower eukaryotes points to an important role for P4 ATPases in vesicular protein trafficking. The human genome encodes fourteen P4 ATPases (fifteen in mouse) of which the cellular and physiological functions are slowly emerging. Thus far, deficiencies of at least two P4 ATPases, ATP8B1 and ATP8A2, are the cause of severe human disease. However, various mouse models and in vitro studies are contributing to our understanding of the cellular and physiological functions of P4-ATPases. This review summarizes current knowledge on the basic function of these phospholipid translocating proteins, their proposed action in intracellular vesicle transport and their physiological role.
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Affiliation(s)
- Vincent A van der Mark
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Meibergdreef 69-71, 1105 BK Amsterdam, The Netherlands.
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Emre Onat O, Gulsuner S, Bilguvar K, Nazli Basak A, Topaloglu H, Tan M, Tan U, Gunel M, Ozcelik T. Missense mutation in the ATPase, aminophospholipid transporter protein ATP8A2 is associated with cerebellar atrophy and quadrupedal locomotion. Eur J Hum Genet 2013; 21:281-5. [PMID: 22892528 PMCID: PMC3573203 DOI: 10.1038/ejhg.2012.170] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 07/03/2012] [Accepted: 07/06/2012] [Indexed: 02/02/2023] Open
Abstract
Cerebellar ataxia, mental retardation and dysequilibrium syndrome is a rare and heterogeneous condition. We investigated a consanguineous family from Turkey with four affected individuals exhibiting the condition. Homozygosity mapping revealed that several shared homozygous regions, including chromosome 13q12. Targeted next-generation sequencing of an affected individual followed by segregation analysis, population screening and prediction approaches revealed a novel missense variant, p.I376M, in ATP8A2. The mutation lies in a highly conserved C-terminal transmembrane region of E1 E2 ATPase domain. The ATP8A2 gene is mainly expressed in brain and development, in particular cerebellum. Interestingly, an unrelated individual has been identified, in whom mental retardation and severe hypotonia is associated with a de novo t(10;13) balanced translocation resulting with the disruption of ATP8A2. These findings suggest that ATP8A2 is involved in the development of the cerebro-cerebellar structures required for posture and gait in humans.
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Affiliation(s)
- Onur Emre Onat
- Department of Molecular Biology and Genetics, Faculty of Science, Bilkent University, Ankara, Turkey
| | - Suleyman Gulsuner
- Department of Molecular Biology and Genetics, Faculty of Science, Bilkent University, Ankara, Turkey
| | - Kaya Bilguvar
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT, USA
- Department of Genetics, Center for Human Genetics and Genomics and Program on Neurogenetics, Yale University School of Medicine, New Haven, CT, USA
| | - Ayse Nazli Basak
- Department of Molecular Biology and Genetics, NDAL Laboratory, School of Arts and Sciences, Bogazici University, Istanbul, Turkey
| | - Haluk Topaloglu
- Department of Pediatric Neurology, Ihsan Dogramaci Children's Hospital, Hacettepe University Faculty of Medicine, Ankara, Turkey
| | - Meliha Tan
- Department of Neurology, Baskent University Faculty of Medicine, Ankara, Turkey
| | - Uner Tan
- Department of Physiology, Cukurova University Faculty of Medicine, Adana, Turkey
| | - Murat Gunel
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT, USA
- Department of Genetics, Center for Human Genetics and Genomics and Program on Neurogenetics, Yale University School of Medicine, New Haven, CT, USA
| | - Tayfun Ozcelik
- Department of Molecular Biology and Genetics, Faculty of Science, Bilkent University, Ankara, Turkey
- Institute of Materials Science and Nanotechnology (UNAM), Bilkent University, Ankara, Turkey
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Kato U, Inadome H, Yamamoto M, Emoto K, Kobayashi T, Umeda M. Role for phospholipid flippase complex of ATP8A1 and CDC50A proteins in cell migration. J Biol Chem 2012; 288:4922-34. [PMID: 23269685 DOI: 10.1074/jbc.m112.402701] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Type IV P-type ATPases (P4-ATPases) and CDC50 family proteins form a putative phospholipid flippase complex that mediates the translocation of aminophospholipids such as phosphatidylserine (PS) and phosphatidylethanolamine (PE) from the outer to inner leaflets of the plasma membrane. In Chinese hamster ovary (CHO) cells, at least eight members of P4-ATPases were identified, but only a single CDC50 family protein, CDC50A, was expressed. We demonstrated that CDC50A associated with and recruited P4-ATPase ATP8A1 to the plasma membrane. Overexpression of CDC50A induced extensive cell spreading and greatly enhanced cell migration. Depletion of either CDC50A or ATP8A1 caused a severe defect in the formation of membrane ruffles, thereby inhibiting cell migration. Analyses of phospholipid translocation at the plasma membrane revealed that the depletion of CDC50A inhibited the inward translocation of both PS and PE, whereas the depletion of ATP8A1 inhibited the translocation of PE but not that of PS, suggesting that the inward translocation of cell-surface PE is involved in cell migration. This hypothesis was further examined by using a PE-binding peptide and a mutant cell line with defective PE synthesis; either cell-surface immobilization of PE by the PE-binding peptide or reduction in the cell-surface content of PE inhibited the formation of membrane ruffles, causing a severe defect in cell migration. These results indicate that the phospholipid flippase complex of ATP8A1 and CDC50A plays a major role in cell migration and suggest that the flippase-mediated translocation of PE at the plasma membrane is involved in the formation of membrane ruffles to promote cell migration.
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Affiliation(s)
- Utako Kato
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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45
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Coleman JA, Quazi F, Molday RS. Mammalian P4-ATPases and ABC transporters and their role in phospholipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:555-74. [PMID: 23103747 DOI: 10.1016/j.bbalip.2012.10.006] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/16/2012] [Accepted: 10/18/2012] [Indexed: 02/08/2023]
Abstract
Transport of phospholipids across cell membranes plays a key role in a wide variety of biological processes. These include membrane biosynthesis, generation and maintenance of membrane asymmetry, cell and organelle shape determination, phagocytosis, vesicle trafficking, blood coagulation, lipid homeostasis, regulation of membrane protein function, apoptosis, etc. P(4)-ATPases and ATP binding cassette (ABC) transporters are the two principal classes of membrane proteins that actively transport phospholipids across cellular membranes. P(4)-ATPases utilize the energy from ATP hydrolysis to flip aminophospholipids from the exocytoplasmic (extracellular/lumen) to the cytoplasmic leaflet of cell membranes generating membrane lipid asymmetry and lipid imbalance which can induce membrane curvature. Many ABC transporters play crucial roles in lipid homeostasis by actively transporting phospholipids from the cytoplasmic to the exocytoplasmic leaflet of cell membranes or exporting phospholipids to protein acceptors or micelles. Recent studies indicate that some ABC proteins can also transport phospholipids in the opposite direction. The importance of P(4)-ATPases and ABC transporters is evident from the findings that mutations in many of these transporters are responsible for severe human genetic diseases linked to defective phospholipid transport. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Affiliation(s)
- Jonathan A Coleman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
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Zhu X, Libby RT, de Vries WN, Smith RS, Wright DL, Bronson RT, Seburn KL, John SWM. Mutations in a P-type ATPase gene cause axonal degeneration. PLoS Genet 2012; 8:e1002853. [PMID: 22912588 PMCID: PMC3415440 DOI: 10.1371/journal.pgen.1002853] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 06/07/2012] [Indexed: 01/13/2023] Open
Abstract
Neuronal loss and axonal degeneration are important pathological features of many neurodegenerative diseases. The molecular mechanisms underlying the majority of axonal degeneration conditions remain unknown. To better understand axonal degeneration, we studied a mouse mutant wabbler-lethal (wl). Wabbler-lethal (wl) mutant mice develop progressive ataxia with pronounced neurodegeneration in the central and peripheral nervous system. Previous studies have led to a debate as to whether myelinopathy or axonopathy is the primary cause of neurodegeneration observed in wl mice. Here we provide clear evidence that wabbler-lethal mutants develop an axonopathy, and that this axonopathy is modulated by Wlds and Bax mutations. In addition, we have identified the gene harboring the disease-causing mutations as Atp8a2. We studied three wl alleles and found that all result from mutations in the Atp8a2 gene. Our analysis shows that ATP8A2 possesses phosphatidylserine translocase activity and is involved in localization of phosphatidylserine to the inner leaflet of the plasma membrane. Atp8a2 is widely expressed in the brain, spinal cord, and retina. We assessed two of the mutant alleles of Atp8a2 and found they are both nonfunctional for the phosphatidylserine translocase activity. Thus, our data demonstrate for the first time that mutation of a mammalian phosphatidylserine translocase causes axon degeneration and neurodegenerative disease. Axonal degeneration is an important pathological feature of many neurodegenerative diseases, such as Alzheimer disease, Parkinson's disease, and amyotrophic lateral sclerosis. In most of these disease conditions, molecular mechanisms of axonal degeneration remain largely unknown. Spontaneous mouse mutants are important in human disease studies. Identification of a disease-causing gene in mice can lead to the identification of the human ortholog as the disease gene in humans. This approach has the power to identify unexpected genes and pathways involved in disease. Our study centered on wabbler lethal (wl) mutant mice, which display axonal degeneration in both the central and peripheral nervous systems. We identified the disease-causing gene in mice with different wl mutations. The mutations are in Atp8a2, a gene encoding a phosphatidylserine translocase. This protein functions to keep phosphatidylserine enriched to the inner leaflet of the plasma membrane. Our study demonstrates a new role for phospholipid asymmetry in maintaining axon health, and it also reveals a novel function for phosphatidyleserine translocase in neurodegenerative diseases.
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Affiliation(s)
- Xianjun Zhu
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
- The Howard Hughes Medical Institute, Bar Harbor, Maine, United States of America
| | - Richard T. Libby
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Wilhelmine N. de Vries
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
- The Howard Hughes Medical Institute, Bar Harbor, Maine, United States of America
| | - Richard S. Smith
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
- The Howard Hughes Medical Institute, Bar Harbor, Maine, United States of America
| | - Dana L. Wright
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | | | - Kevin L. Seburn
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Simon W. M. John
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
- The Howard Hughes Medical Institute, Bar Harbor, Maine, United States of America
- Department of Ophthalmology, Tufts University of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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47
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Xu Q, Yang GY, Liu N, Xu P, Chen YL, Zhou Z, Luo ZG, Ding X. P4-ATPase ATP8A2 acts in synergy with CDC50A to enhance neurite outgrowth. FEBS Lett 2012; 586:1803-12. [PMID: 22641037 DOI: 10.1016/j.febslet.2012.05.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/12/2012] [Accepted: 05/14/2012] [Indexed: 12/28/2022]
Abstract
P(4)-ATPases are lipid flippases that transport phospholipids across cellular membranes, playing vital roles in cell function. In humans, the disruption of the P(4)-ATPase ATP8A2 gene causes a severe neurological phenotype. Here, we found that Atp8a2 mRNA was highly expressed in PC12 cells, hippocampal neurons and the brain. Overexpression of ATP8A2 increased the length of neurite outgrowth in NGF-induced PC12 cells and in primary cultures of rat hippocampal neurons. Inducing the loss of function of CDC50A in hippocampal neurons via RNA interference reduced neurite outgrowth, and the co-overexpression of CDC50A and ATP8A2 in PC12 cells enhanced NGF-induced neurite outgrowth. These results indicate that ATP8A2, acting in synergy with CDC50A, performs an important role in neurite outgrowth in neurons.
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Affiliation(s)
- Qin Xu
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences (SIBS), Graduate School of the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China
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48
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Mulligan MK, Wang X, Adler AL, Mozhui K, Lu L, Williams RW. Complex control of GABA(A) receptor subunit mRNA expression: variation, covariation, and genetic regulation. PLoS One 2012; 7:e34586. [PMID: 22506031 PMCID: PMC3323555 DOI: 10.1371/journal.pone.0034586] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 03/06/2012] [Indexed: 12/13/2022] Open
Abstract
GABA type-A receptors are essential for fast inhibitory neurotransmission and are critical in brain function. Surprisingly, expression of receptor subunits is highly variable among individuals, but the cause and impact of this fluctuation remains unknown. We have studied sources of variation for all 19 receptor subunits using massive expression data sets collected across multiple brain regions and platforms in mice and humans. Expression of Gabra1, Gabra2, Gabrb2, Gabrb3, and Gabrg2 is highly variable and heritable among the large cohort of BXD strains derived from crosses of fully sequenced parents—C57BL/6J and DBA/2J. Genetic control of these subunits is complex and highly dependent on tissue and mRNA region. Remarkably, this high variation is generally not linked to phenotypic differences. The single exception is Gabrb3, a locus that is linked to anxiety. We identified upstream genetic loci that influence subunit expression, including three unlinked regions of chromosome 5 that modulate the expression of nine subunits in hippocampus, and that are also associated with multiple phenotypes. Candidate genes within these loci include, Naaa, Nos1, and Zkscan1. We confirmed a high level of coexpression for subunits comprising the major channel—Gabra1, Gabrb2, and Gabrg2—and identified conserved members of this expression network in mice and humans. Gucy1a3, Gucy1b3, and Lis1 are novel and conserved associates of multiple subunits that are involved in inhibitory signaling. Finally, proximal and distal regions of the 3′ UTRs of single subunits have remarkably independent expression patterns in both species. However, corresponding regions of different subunits often show congruent genetic control and coexpression (proximal-to-proximal or distal-to-distal), even in the absence of sequence homology. Our findings identify novel sources of variation that modulate subunit expression and highlight the extraordinary capacity of biological networks to buffer 4–100 fold differences in mRNA levels.
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Affiliation(s)
- Megan K Mulligan
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America.
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Critical role of a transmembrane lysine in aminophospholipid transport by mammalian photoreceptor P4-ATPase ATP8A2. Proc Natl Acad Sci U S A 2012; 109:1449-54. [PMID: 22307598 DOI: 10.1073/pnas.1108862109] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
ATP8A2 is a P(4)-ATPase ("flippase") located in membranes of retinal photoreceptors, brain cells, and testis, where it mediates transport of aminophospholipids toward the cytoplasmic leaflet. It has long been an enigma whether the mechanism of P(4)-ATPases resembles that of the well-characterized cation-transporting P-type ATPases, and it is unknown whether the flippases interact directly with the lipid and with counterions. Our results demonstrate that ATP8A2 forms a phosphoenzyme intermediate at the conserved aspartate (Asp(416)) in the P-type ATPase signature sequence and exists in E(1)P and E(2)P forms similar to the archetypical P-type ATPases. Using the properties of the phosphoenzyme, the partial reaction steps of the transport cycle were examined, and the roles of conserved residues Asp(196), Glu(198), Lys(873), and Asn(874) in the transport mechanism were elucidated. The former two residues in the A-domain T/D-G-E-S/T motif are involved in catalysis of E(2)P dephosphorylation, the glutamate being essential. Transported aminophospholipids activate the dephosphorylation similar to K(+) activation of dephosphorylation in Na(+),K(+)-ATPase. Lys(873) mutants (particularly K873A and K873E) display a markedly reduced sensitivity to aminophospholipids. Hence, Lys(873), located in transmembrane segment M5 at a "hot spot" for cation binding in Ca(2+)-ATPase and Na(+),K(+)-ATPase, appears to participate directly in aminophospholipid binding or to mediate a crucial interaction within the ATP8A2-CDC50 complex. By contrast, Lys(865) is unimportant for aminophospholipid sensitivity. Binding of Na(+), H(+), K(+), Cl(-), or Ca(2+) to the E(1) form as a counterion is not required for activation of phosphorylation from ATP. Therefore, phospholipids could be the only substrate transported by ATP8A2.
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Sebastian TT, Baldridge RD, Xu P, Graham TR. Phospholipid flippases: building asymmetric membranes and transport vesicles. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:1068-77. [PMID: 22234261 DOI: 10.1016/j.bbalip.2011.12.007] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 12/14/2011] [Accepted: 12/16/2011] [Indexed: 01/25/2023]
Abstract
Phospholipid flippases in the type IV P-type ATPase family (P4-ATPases) are essential components of the Golgi, plasma membrane and endosomal system that play critical roles in membrane biogenesis. These pumps flip phospholipid across the bilayer to create an asymmetric membrane structure with substrate phospholipids, such as phosphatidylserine and phosphatidylethanolamine, enriched within the cytosolic leaflet. The P4-ATPases also help form transport vesicles that bud from Golgi and endosomal membranes, thereby impacting the sorting and localization of many different proteins in the secretory and endocytic pathways. At the organismal level, P4-ATPase deficiencies are linked to liver disease, obesity, diabetes, hearing loss, neurological deficits, immune deficiency and reduced fertility. Here, we review the biochemical, cellular and physiological functions of P4-ATPases, with an emphasis on their roles in vesicle-mediated protein transport. This article is part of a Special Issue entitled Lipids and Vesicular Transport.
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Affiliation(s)
- Tessy T Sebastian
- Department of Biological Sciences, Vanderbilt University, Nashville TN 37235, USA
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