51
|
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.
Collapse
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
| |
Collapse
|
52
|
Hiraizumi M, Yamashita K, Nishizawa T, Nureki O. Cryo-EM structures capture the transport cycle of the P4-ATPase flippase. Science 2019; 365:1149-1155. [PMID: 31416931 DOI: 10.1126/science.aay3353] [Citation(s) in RCA: 106] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 08/06/2019] [Indexed: 12/13/2022]
Abstract
In eukaryotic membranes, type IV P-type adenosine triphosphatases (P4-ATPases) mediate the translocation of phospholipids from the outer to the inner leaflet and maintain lipid asymmetry, which is critical for membrane trafficking and signaling pathways. Here, we report the cryo-electron microscopy structures of six distinct intermediates of the human ATP8A1-CDC50a heterocomplex at resolutions of 2.6 to 3.3 angstroms, elucidating the lipid translocation cycle of this P4-ATPase. ATP-dependent phosphorylation induces a large rotational movement of the actuator domain around the phosphorylation site in the phosphorylation domain, accompanied by lateral shifts of the first and second transmembrane helices, thereby allowing phosphatidylserine binding. The phospholipid head group passes through the hydrophilic cleft, while the acyl chain is exposed toward the lipid environment. These findings advance our understanding of the flippase mechanism and the disease-associated mutants of P4-ATPases.
Collapse
Affiliation(s)
- Masahiro Hiraizumi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Discovery Technology Laboratories, Innovative Research Division, Mitsubishi Tanabe Pharma Corporation, 1000 Kamoshida, Aoba-ku, Yokohama, 227-0033, Japan
| | - Keitaro Yamashita
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Tomohiro Nishizawa
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| |
Collapse
|
53
|
Timcenko M, Lyons JA, Januliene D, Ulstrup JJ, Dieudonné T, Montigny C, Ash MR, Karlsen JL, Boesen T, Kühlbrandt W, Lenoir G, Moeller A, Nissen P. Structure and autoregulation of a P4-ATPase lipid flippase. Nature 2019; 571:366-370. [DOI: 10.1038/s41586-019-1344-7] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 05/28/2019] [Indexed: 02/07/2023]
|
54
|
Günay-Esiyok Ö, Scheib U, Noll M, Gupta N. An unusual and vital protein with guanylate cyclase and P4-ATPase domains in a pathogenic protist. Life Sci Alliance 2019; 2:2/3/e201900402. [PMID: 31235476 PMCID: PMC6592433 DOI: 10.26508/lsa.201900402] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 06/06/2019] [Accepted: 06/06/2019] [Indexed: 12/13/2022] Open
Abstract
Toxoplasma gondii harbors an alveolate-specific guanylate cyclase linked to P-type ATPase motifs, which is an essential actuator of cGMP-dependent gliding motility, egress, and invasion during acute infection. cGMP signaling is one of the master regulators of diverse functions in eukaryotes; however, its architecture and functioning in protozoans remain poorly understood. Herein, we report an exclusive guanylate cyclase coupled with N-terminal P4-ATPase in a common parasitic protist, Toxoplasma gondii. This bulky protein (477-kD), termed TgATPaseP-GC to fairly reflect its envisaged multifunctionality, localizes in the plasma membrane at the apical pole of the parasite, whereas the corresponding cGMP-dependent protein kinase (TgPKG) is distributed in the cytomembranes. TgATPaseP-GC is refractory to genetic deletion, and its CRISPR/Cas9–assisted disruption aborts the lytic cycle of T. gondii. Besides, Cre/loxP–mediated knockdown of TgATPaseP-GC reduced the synthesis of cGMP and inhibited the parasite growth due to impairments in the motility-dependent egress and invasion events. Equally, repression of TgPKG by a similar strategy recapitulated phenotypes of the TgATPaseP-GC–depleted mutant. Notably, despite a temporally restricted function, TgATPaseP-GC is expressed constitutively throughout the lytic cycle, entailing a post-translational regulation of cGMP signaling. Not least, the occurrence of TgATPaseP-GC orthologs in several other alveolates implies a divergent functional repurposing of cGMP signaling in protozoans, and offers an excellent drug target against the parasitic protists.
Collapse
Affiliation(s)
- Özlem Günay-Esiyok
- Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Ulrike Scheib
- Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Matthias Noll
- Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| | - Nishith Gupta
- Institute of Biology, Faculty of Life Sciences, Humboldt University, Berlin, Germany
| |
Collapse
|
55
|
Stanimirovic DB, Sandhu JK, Costain WJ. Emerging Technologies for Delivery of Biotherapeutics and Gene Therapy Across the Blood-Brain Barrier. BioDrugs 2019; 32:547-559. [PMID: 30306341 PMCID: PMC6290705 DOI: 10.1007/s40259-018-0309-y] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Antibody, immuno- and gene therapies developed for neurological indications face a delivery challenge posed by various anatomical and physiological barriers within the central nervous system (CNS); most notably, the blood–brain barrier (BBB). Emerging delivery technologies for biotherapeutics have focused on trans-cellular pathways across the BBB utilizing receptor-mediated transcytosis (RMT). ‘Traditionally’ targeted RMT receptors, transferrin receptor (TfR) and insulin receptor (IR), are ubiquitously expressed and pose numerous translational challenges during development, including species differences and safety risks. Recent advances in antibody engineering technologies and discoveries of RMT targets and BBB-crossing antibodies that are more BBB-selective have combined to create a new preclinical pipeline of BBB-crossing biotherapeutics with improved efficacy and safety. Novel BBB-selective RMT targets and carrier antibodies have exposed additional opportunities for re-targeting gene delivery vectors or nanocarriers for more efficient brain delivery. Emergence and refinement of core technologies of genetic engineering and editing as well as biomanufacturing of viral vectors and cell-derived products have de-risked the path to the development of systemic gene therapy approaches for the CNS. In particular, brain-tropic viral vectors and extracellular vesicles have recently expanded the repertoire of brain delivery strategies for biotherapeutics. Whereas protein biotherapeutics and bispecific antibodies enabled for BBB transcytosis are rapidly heading towards clinical trials, systemic gene therapy approaches for CNS will likely remain in research phase for the foreseeable future. The promise and limitations of these emerging cross-BBB delivery technologies are further discussed in this article.
Collapse
Affiliation(s)
- Danica B Stanimirovic
- Human Health Therapeutics Research Centre, Translational Bioscience, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, Canada.
| | - Jagdeep K Sandhu
- Human Health Therapeutics Research Centre, Translational Bioscience, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, Canada
| | - Will J Costain
- Human Health Therapeutics Research Centre, Translational Bioscience, National Research Council Canada, 1200 Montreal Road, Ottawa, ON, Canada
| |
Collapse
|
56
|
Liou AY, Molday LL, Wang J, Andersen JP, Molday RS. Identification and functional analyses of disease-associated P4-ATPase phospholipid flippase variants in red blood cells. J Biol Chem 2019; 294:6809-6821. [PMID: 30850395 DOI: 10.1074/jbc.ra118.007270] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/06/2019] [Indexed: 02/04/2023] Open
Abstract
ATP-dependent phospholipid flippase activity crucial for generating lipid asymmetry was first detected in red blood cell (RBC) membranes, but the P4-ATPases responsible have not been directly determined. Using affinity-based MS, we show that ATP11C is the only abundant P4-ATPase phospholipid flippase in human RBCs, whereas ATP11C and ATP8A1 are the major P4-ATPases in mouse RBCs. We also found that ATP11A and ATP11B are present at low levels. Mutations in the gene encoding ATP11C are responsible for blood and liver disorders, but the disease mechanisms are not known. Using heterologous expression, we show that the T415N substitution in the phosphorylation motif of ATP11C, responsible for congenital hemolytic anemia, reduces ATP11C expression, increases retention in the endoplasmic reticulum, and decreases ATPase activity by 61% relative to WT ATP11C. The I355K substitution in the transmembrane domain associated with cholestasis and anemia in mice was expressed at WT levels and trafficked to the plasma membrane but was devoid of activity. We conclude that the T415N variant causes significant protein misfolding, resulting in low protein expression, cellular mislocalization, and reduced functional activity. In contrast, the I355K variant folds and traffics normally but lacks key contacts required for activity. We propose that the loss in ATP11C phospholipid flippase activity coupled with phospholipid scramblase activity results in the exposure of phosphatidylserine on the surface of RBCs, decreasing RBC survival and resulting in anemia.
Collapse
Affiliation(s)
- Angela Y Liou
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - Laurie L Molday
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - Jiao Wang
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| | - Jens Peter Andersen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Building 1160, DK-8000 Aarhus C, Denmark
| | - Robert S Molday
- From the Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada and
| |
Collapse
|
57
|
The lipid head group is the key element for substrate recognition by the P4 ATPase ALA2: a phosphatidylserine flippase. Biochem J 2019; 476:783-794. [PMID: 30755463 PMCID: PMC6402034 DOI: 10.1042/bcj20180891] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 02/05/2019] [Accepted: 02/12/2019] [Indexed: 11/30/2022]
Abstract
Type IV P-type ATPases (P4 ATPases) are lipid flippases that catalyze phospholipid transport from the exoplasmic to the cytoplasmic leaflet of cellular membranes, but the mechanism by which they recognize and transport phospholipids through the lipid bilayer remains unknown. In the present study, we succeeded in purifying recombinant aminophospholipid ATPase 2 (ALA2), a member of the P4 ATPase subfamily in Arabidopsis thaliana, in complex with the ALA-interacting subunit 5 (ALIS5). The ATP hydrolytic activity of the ALA2–ALIS5 complex was stimulated in a highly specific manner by phosphatidylserine. Small changes in the stereochemistry or the functional groups of the phosphatidylserine head group affected enzymatic activity, whereas alteration in the length and composition of the acyl chains only had minor effects. Likewise, the enzymatic activity of the ALA2–ALIS5 complex was stimulated by both mono- and di-acyl phosphatidylserines. Taken together, the results identify the lipid head group as the key structural element for substrate recognition by the P4 ATPase.
Collapse
|
58
|
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.
Collapse
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
| |
Collapse
|
59
|
Shin HW, Takatsu H. Substrates of P4‐ATPases: beyond aminophospholipids (phosphatidylserine and phosphatidylethanolamine). FASEB J 2018; 33:3087-3096. [DOI: 10.1096/fj.201801873r] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Hye-Won Shin
- Graduate School of Pharmaceutical SciencesKyoto University Kyoto Japan
| | - Hiroyuki Takatsu
- Graduate School of Pharmaceutical SciencesKyoto University Kyoto Japan
| |
Collapse
|
60
|
Hanadate Y, Saito-Nakano Y, Nakada-Tsukui K, Nozaki T. Identification and Characterization of the Entamoeba Histolytica Rab8a Binding Protein: A Cdc50 Homolog. Int J Mol Sci 2018; 19:ijms19123831. [PMID: 30513690 PMCID: PMC6321534 DOI: 10.3390/ijms19123831] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 11/24/2018] [Accepted: 11/27/2018] [Indexed: 12/31/2022] Open
Abstract
Membrane traffic plays a pivotal role in virulence in the enteric protozoan parasite Entamoeba histolytica. EhRab8A small GTPase is a key regulator of membrane traffic at the endoplasmic reticulum (ER) of this protist and is involved in the transport of plasma membrane proteins. Here we identified the binding proteins of EhRab8A. The Cdc50 homolog, a non-catalytic subunit of lipid flippase, was identified as an EhRab8A binding protein candidate by affinity coimmunoprecipitation. Binding of EhRab8A to EhCdc50 was also confirmed by reciprocal immunoprecipitation and blue-native polyacrylamide gel electrophoresis, the latter of which revealed an 87 kDa complex. Indirect immunofluorescence imaging with and without Triton X100 showed that endogenous EhCdc50 localized on the surface in the absence of permeabilizing agent but was observed on the intracellular structures and overlapped with the ER marker Bip when Triton X100 was used. Overexpression of N-terminal HA-tagged EhCdc50 impaired its translocation to the plasma membrane and caused its accumulation in the ER. As reported previously in other organisms, overexpression and accumulation of Cdc50 in the ER likely inhibited surface transport and function of the plasma membrane lipid flippase P4-ATPase. Interestingly, HA-EhCdc50-expressing trophozoites gained resistance to miltefosine, which is consistent with the prediction that HA-EhCdc50 overexpression caused its accumulation in the ER and mislocalization of the unidentified lipid flippase. Similarly, EhRab8A gene silenced trophozoites showed increased resistance to miltefosine, supporting EhRab8A-dependent transport of EhCdc50. This study demonstrated for the first time that EhRab8A mediates the transport of EhCdc50 and lipid flippase P4-ATPase from the ER to the plasma membrane.
Collapse
Affiliation(s)
- Yuki Hanadate
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
| | - Yumiko Saito-Nakano
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
| | - Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
| | - Tomoyoshi Nozaki
- Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
- Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.
| |
Collapse
|
61
|
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: 19] [Impact Index Per Article: 3.2] [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.
Collapse
|
62
|
Takasugi N, Araya R, Kamikubo Y, Kaneshiro N, Imaoka R, Jin H, Kashiyama T, Hashimoto Y, Kurosawa M, Uehara T, Nukina N, Sakurai T. TMEM30A is a candidate interacting partner for the β-carboxyl-terminal fragment of amyloid-β precursor protein in endosomes. PLoS One 2018; 13:e0200988. [PMID: 30086173 PMCID: PMC6080755 DOI: 10.1371/journal.pone.0200988] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 07/08/2018] [Indexed: 11/19/2022] Open
Abstract
Although the aggregation of amyloid-β peptide (Aβ) clearly plays a central role in the pathogenesis of Alzheimer's disease (AD), endosomal traffic dysfunction is considered to precede Aβ aggregation and trigger AD pathogenesis. A body of evidence suggests that the β-carboxyl-terminal fragment (βCTF) of amyloid-β precursor protein (APP), which is the direct precursor of Aβ, accumulates in endosomes and causes vesicular traffic impairment. However, the mechanism underlying this impairment remains unclear. Here we identified TMEM30A as a candidate partner for βCTF. TMEM30A is a subcomponent of lipid flippase that translocates phospholipids from the outer to the inner leaflet of the lipid bilayer. TMEM30A physically interacts with βCTF in endosomes and may impair vesicular traffic, leading to abnormally enlarged endosomes. APP traffic is also concomitantly impaired, resulting in the accumulation of APP-CTFs, including βCTF. In addition, we found that expressed BACE1 accumulated in enlarged endosomes and increased Aβ production. Our data suggested that TMEM30A is involved in βCTF-dependent endosome abnormalities that are related to Aβ overproduction.
Collapse
Affiliation(s)
- Nobumasa Takasugi
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Runa Araya
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Yuji Kamikubo
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Nanaka Kaneshiro
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Ryosuke Imaoka
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Hao Jin
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Taku Kashiyama
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Yoshie Hashimoto
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Masaru Kurosawa
- Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Saitama, Japan
| | - Takashi Uehara
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Nobuyuki Nukina
- Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Saitama, Japan
- Laboratory of Structural Neuropathology, Doshisha University Graduate School of Brain Science, Kyoto, Japan
- Department of Neuroscience for Neurodegenerative Disorders, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Takashi Sakurai
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Saitama, Japan
- * E-mail:
| |
Collapse
|
63
|
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: 47] [Impact Index Per Article: 7.8] [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.
Collapse
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.
| |
Collapse
|
64
|
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: 17] [Impact Index Per Article: 2.8] [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.
Collapse
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
| |
Collapse
|
65
|
Segawa K, Kurata S, Nagata S. The CDC50A extracellular domain is required for forming a functional complex with and chaperoning phospholipid flippases to the plasma membrane. J Biol Chem 2017; 293:2172-2182. [PMID: 29276178 DOI: 10.1074/jbc.ra117.000289] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 12/21/2017] [Indexed: 02/04/2023] Open
Abstract
Flippases are enzymes that translocate phosphatidylserine (PtdSer) and phosphatidylethanolamine (PtdEtn) from the outer to the inner leaflet in the lipid bilayer of the plasma membrane, leading to the asymmetric distribution of aminophospholipids in the membrane. One mammalian phospholipid flippase at the plasma membrane is ATP11C, a type IV P-type ATPase (P4-ATPase) that forms a heterocomplex with the transmembrane protein CDC50A. However, the structural features in CDC50A that support the function of ATP11C and other P4-ATPases have not been characterized. Here, using error-prone PCR-mediated mutagenesis of human CDC50A cDNA followed by functional screening and deep sequencing, we identified 14 amino acid residues that affect ATP11C's flippase activity. These residues were all located in CDC50A's extracellular domain and were evolutionarily well-conserved. Most of the mutations decreased CDC50A's ability to chaperone ATP11C and other P4-ATPases to their destinations. The CDC50A mutants failed to form a stable complex with ATP11C and could not induce ATP11C's PtdSer-dependent ATPase activity. Notably, one mutant variant could form a stable complex with ATP11C and transfer ATP11C to the plasma membrane, yet the ATP11C complexed with this CDC50A variant had very weak or little PtdSer- or PtdEtn-dependent ATPase activity. These results indicated that the extracellular domain of CDC50A has important roles both in CDC50A's ability to chaperone ATP11C to the plasma membrane and in inducing ATP11C's ATP hydrolysis-coupled flippase activity.
Collapse
Affiliation(s)
- Katsumori Segawa
- From the Laboratory of Biochemistry and Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - Sachiko Kurata
- From the Laboratory of Biochemistry and Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - Shigekazu Nagata
- From the Laboratory of Biochemistry and Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| |
Collapse
|
66
|
Liu L, Zhang L, Zhang L, Yang F, Zhu X, Lu Z, Yang Y, Lu H, Feng L, Wang Z, Chen H, Yan S, Wang L, Ju Z, Jin H, Zhu X. Hepatic Tmem30a Deficiency Causes Intrahepatic Cholestasis by Impairing Expression and Localization of Bile Salt Transporters. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 187:2775-2787. [PMID: 28919113 DOI: 10.1016/j.ajpath.2017.08.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 07/21/2017] [Accepted: 08/17/2017] [Indexed: 02/07/2023]
Abstract
Mutations in ATP8B1 or ATP11C (members of P4-type ATPases) cause progressive familial intrahepatic cholestasis type 1 in human or intrahepatic cholestasis in mice. Transmembrane protein 30A (TMEM30A), a β-subunit, is essential for the function of ATP8B1 and ATP11C. However, its role in the etiology of cholestasis remains poorly understood. To investigate the function of TMEM30A in bile salt (BS) homeostasis, we developed Tmem30a liver-specific knockout (LKO) mice. Tmem30a LKO mice experienced hyperbilirubinemia, hypercholanemia, inflammatory infiltration, ductular proliferation, and liver fibrosis. The expression and membrane localization of ATP8B1 and ATP11C were significantly reduced in Tmem30a LKO mice, which correlated with the impaired expression and localization of BS transporters, such as OATP1A4, OATP1B2, NTCP, BSEP, and MRP2. The proteasome inhibitor bortezomib partially restored total protein levels of BS transporters but not the localization of BS transporters in the membrane. Furthermore, the expression of nuclear receptors, including FXRα, RXRα, HNF4α, LRH-1, and SHP, was also down-regulated. A cholic acid-supplemented diet exacerbated the liver damage in Tmem30a LKO mice. TMEM30A deficiency led to intrahepatic cholestasis in mice by impairing the expression and localization of BS transporters and the expression of related nuclear receptors. Therefore, TMEM30A may be a novel genetic determinant of intrahepatic cholestasis.
Collapse
Affiliation(s)
- Leiming Liu
- Laboratory of Cancer Biology, Key Laboratory of Biotherapy in Zhejiang Province, Sir Runrun Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China; Key Laboratory of Regenerative Medicine of Ministry of Education, Institute of Aging and Regenerative Medicine, Jinan University, Guangzhou, China
| | - Lingling Zhang
- Institute of Aging Research, Leibniz Link Partner Group on Stem Cell Aging, School of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Lin Zhang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China; Key Laboratory for NeuroInformation of Ministry of Education and Medicine Information Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Fan Yang
- Key Laboratory of Regenerative Medicine of Ministry of Education, Institute of Aging and Regenerative Medicine, Jinan University, Guangzhou, China; Leibniz Institute for Age Research - Fritz Lipmann Institute, Friedrich-Schiller University of Jena, Jena, Germany
| | - Xudong Zhu
- Institute of Aging Research, Leibniz Link Partner Group on Stem Cell Aging, School of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Zhongjie Lu
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, Division of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yeming Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China; Key Laboratory for NeuroInformation of Ministry of Education and Medicine Information Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Haiqi Lu
- Laboratory of Cancer Biology, Key Laboratory of Biotherapy in Zhejiang Province, Sir Runrun Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Lifeng Feng
- Laboratory of Cancer Biology, Key Laboratory of Biotherapy in Zhejiang Province, Sir Runrun Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Zhuo Wang
- Laboratory of Cancer Biology, Key Laboratory of Biotherapy in Zhejiang Province, Sir Runrun Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Hui Chen
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, Division of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Sheng Yan
- Key Laboratory of Combined Multi-Organ Transplantation, Ministry of Public Health, Division of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Lin Wang
- Department of Hepato-Biliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Zhenyu Ju
- Key Laboratory of Regenerative Medicine of Ministry of Education, Institute of Aging and Regenerative Medicine, Jinan University, Guangzhou, China; Institute of Aging Research, Leibniz Link Partner Group on Stem Cell Aging, School of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Hongchuan Jin
- Laboratory of Cancer Biology, Key Laboratory of Biotherapy in Zhejiang Province, Sir Runrun Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study and School of Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China; Key Laboratory for NeuroInformation of Ministry of Education and Medicine Information Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China.
| |
Collapse
|
67
|
Gantzel RH, Mogensen LS, Mikkelsen SA, Vilsen B, Molday RS, Vestergaard AL, Andersen JP. Disease mutations reveal residues critical to the interaction of P4-ATPases with lipid substrates. Sci Rep 2017; 7:10418. [PMID: 28874751 PMCID: PMC5585164 DOI: 10.1038/s41598-017-10741-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 08/14/2017] [Indexed: 02/08/2023] Open
Abstract
Phospholipid flippases (P4-ATPases) translocate specific phospholipids from the exoplasmic to the cytoplasmic leaflet of membranes. While there is good evidence that the overall molecular structure of flippases is similar to that of P-type ATPase ion-pumps, the transport pathway for the “giant” lipid substrate has not been determined. ATP8A2 is a flippase with selectivity toward phosphatidylserine (PS), possessing a net negatively charged head group, whereas ATP8B1 exhibits selectivity toward the electrically neutral phosphatidylcholine (PC). Setting out to elucidate the functional consequences of flippase disease mutations, we have identified residues of ATP8A2 that are critical to the interaction with the lipid substrate during the translocation process. Among the residues pinpointed are I91 and L308, which are positioned near proposed translocation routes through the protein. In addition we pinpoint two juxtaposed oppositely charged residues, E897 and R898, in the exoplasmic loop between transmembrane helices 5 and 6. The glutamate is conserved between PS and PC flippases, whereas the arginine is replaced by a negatively charged aspartate in ATP8B1. Our mutational analysis suggests that the glutamate repels the PS head group, whereas the arginine minimizes this repulsion in ATP8A2, thereby contributing to control the entry of the phospholipid substrate into the translocation pathway.
Collapse
Affiliation(s)
- Rasmus H Gantzel
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark
| | - Louise S Mogensen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark
| | - Stine A Mikkelsen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark
| | - Bente Vilsen
- 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, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada.,Department of Ophthalmology and Visual Sciences, Centre for Macular Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Anna L Vestergaard
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark.,Laboratory for Immuno-Endocrinology, Department of Biomedical Sciences, University of Copenhagen, DK-2200, Copenhagen N, Denmark
| | - Jens P Andersen
- Department of Biomedicine, Aarhus University, Ole Worms Allé 4, Bldg. 1160, DK-8000, Aarhus C, Denmark.
| |
Collapse
|
68
|
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.
Collapse
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.
| |
Collapse
|
69
|
Azouaoui H, Montigny C, Dieudonné T, Champeil P, Jacquot A, Vázquez-Ibar JL, Le Maréchal P, Ulstrup J, Ash MR, Lyons JA, Nissen P, Lenoir G. High phosphatidylinositol 4-phosphate (PI4P)-dependent ATPase activity for the Drs2p-Cdc50p flippase after removal of its N- and C-terminal extensions. J Biol Chem 2017; 292:7954-7970. [PMID: 28302728 DOI: 10.1074/jbc.m116.751487] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 03/10/2017] [Indexed: 01/08/2023] Open
Abstract
P4-ATPases, also known as phospholipid flippases, are responsible for creating and maintaining transbilayer lipid asymmetry in eukaryotic cell membranes. Here, we use limited proteolysis to investigate the role of the N and C termini in ATP hydrolysis and auto-inhibition of the yeast flippase Drs2p-Cdc50p. We show that limited proteolysis of the detergent-solubilized and purified yeast flippase may result in more than 1 order of magnitude increase of its ATPase activity, which remains dependent on phosphatidylinositol 4-phosphate (PI4P), a regulator of this lipid flippase, and specific to a phosphatidylserine substrate. Using thrombin as the protease, Cdc50p remains intact and in complex with Drs2p, which is cleaved at two positions, namely after Arg104 and after Arg 1290, resulting in a homogeneous sample lacking 104 and 65 residues from its N and C termini, respectively. Removal of the 1291-1302-amino acid region of the C-terminal extension is critical for relieving the auto-inhibition of full-length Drs2p, whereas the 1-104 N-terminal residues have an additional but more modest significance for activity. The present results therefore reveal that trimming off appropriate regions of the terminal extensions of Drs2p can greatly increase its ATPase activity in the presence of PI4P and demonstrate that relief of such auto-inhibition remains compatible with subsequent regulation by PI4P. These experiments suggest that activation of the Drs2p-Cdc50p flippase follows a multistep mechanism, with preliminary release of a number of constraints, possibly through the binding of regulatory proteins in the trans-Golgi network, followed by full activation by PI4P.
Collapse
Affiliation(s)
- Hassina Azouaoui
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, F-91198, Gif-sur-Yvette Cedex, France
| | - Cédric Montigny
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, F-91198, Gif-sur-Yvette Cedex, France
| | - Thibaud Dieudonné
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, F-91198, Gif-sur-Yvette Cedex, France
| | - Philippe Champeil
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, F-91198, Gif-sur-Yvette Cedex, France
| | - Aurore Jacquot
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, F-91198, Gif-sur-Yvette Cedex, France
| | - José Luis Vázquez-Ibar
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, F-91198, Gif-sur-Yvette Cedex, France
| | - Pierre Le Maréchal
- the Neuro-PSI-UMR CNRS 9197, Bâtiment 430, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France, and
| | - Jakob Ulstrup
- the DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Department of Molecular Biology and Genetics, Danish National Research Foundation, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Miriam-Rose Ash
- the DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Department of Molecular Biology and Genetics, Danish National Research Foundation, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Joseph A Lyons
- the DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Department of Molecular Biology and Genetics, Danish National Research Foundation, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Poul Nissen
- the DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Department of Molecular Biology and Genetics, Danish National Research Foundation, Aarhus University, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Guillaume Lenoir
- From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, F-91198, Gif-sur-Yvette Cedex, France,
| |
Collapse
|
70
|
Chalat M, Moleschi K, Molday RS. C-terminus of the P4-ATPase ATP8A2 functions in protein folding and regulation of phospholipid flippase activity. Mol Biol Cell 2016; 28:452-462. [PMID: 27932490 PMCID: PMC5341728 DOI: 10.1091/mbc.e16-06-0453] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 10/28/2016] [Accepted: 12/01/2016] [Indexed: 12/18/2022] Open
Abstract
ATP8A2 is a P4-ATPase that flips phosphatidylserine and phosphatidylethanolamine across cell membranes. This generates membrane phospholipid asymmetry, a property important in many cellular processes, including vesicle trafficking. ATP8A2 deficiency causes severe neurodegenerative diseases. We investigated the role of the C-terminus of ATP8A2 in its expression, subcellular localization, interaction with its subunit CDC50A, and function as a phosphatidylserine flippase. C-terminal deletion mutants exhibited a reduced tendency to solubilize in mild detergent and exit the endoplasmic reticulum. The solubilized protein, however, assembled with CDC50A and displayed phosphatidylserine flippase activity. Deletion of the C-terminal 33 residues resulted in reduced phosphatidylserine-dependent ATPase activity, phosphatidylserine flippase activity, and neurite extension in PC12 cells. These reduced activities were reversed with 60- and 80-residue C-terminal deletions. Unlike the yeast P4-ATPase Drs2, ATP8A2 is not regulated by phosphoinositides but undergoes phosphorylation on the serine residue within a CaMKII target motif. We propose a model in which the C-terminus of ATP8A2 consists of an autoinhibitor domain upstream of the C-terminal 33 residues and an anti-autoinhibitor domain at the extreme C-terminus. The latter blocks the inhibitory activity of the autoinhibitor domain. We conclude that the C-terminus plays an important role in the efficient folding and regulation of ATP8A2.
Collapse
Affiliation(s)
- Madhavan Chalat
- Department of Biochemistry and Molecular Biology, Centre for Macular Research, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Kody Moleschi
- Department of Biochemistry and Molecular Biology, Centre for Macular Research, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, Centre for Macular Research, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| |
Collapse
|
71
|
Tanaka Y, Ono N, Shima T, Tanaka G, Katoh Y, Nakayama K, Takatsu H, Shin HW. The phospholipid flippase ATP9A is required for the recycling pathway from the endosomes to the plasma membrane. Mol Biol Cell 2016; 27:3883-3893. [PMID: 27733620 PMCID: PMC5170610 DOI: 10.1091/mbc.e16-08-0586] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 09/30/2016] [Accepted: 10/04/2016] [Indexed: 12/20/2022] Open
Abstract
ATP9A is localized to phosphatidylserine-positive early and recycling endosomes, but not late endosomes, in HeLa cells. ATP9A plays a crucial role in recycling of transferrin and glucose transporter 1 from endosomes to the plasma membrane. Type IV P-type ATPases (P4-ATPases) are phospholipid flippases that translocate phospholipids from the exoplasmic (or luminal) to the cytoplasmic leaflet of lipid bilayers. In Saccharomyces cerevisiae, P4-ATPases are localized to specific subcellular compartments and play roles in compartment-mediated membrane trafficking; however, roles of mammalian P4-ATPases in membrane trafficking are poorly understood. We previously reported that ATP9A, one of 14 human P4-ATPases, is localized to endosomal compartments and the Golgi complex. In this study, we found that ATP9A is localized to phosphatidylserine (PS)-positive early and recycling endosomes, but not late endosomes, in HeLa cells. Depletion of ATP9A delayed the recycling of transferrin from endosomes to the plasma membrane, although it did not affect the morphology of endosomal structures. Moreover, depletion of ATP9A caused accumulation of glucose transporter 1 in endosomes, probably by inhibiting their recycling. By contrast, depletion of ATP9A affected neither the early/late endosomal transport and degradation of epidermal growth factor (EGF) nor the transport of Shiga toxin B fragment from early/recycling endosomes to the Golgi complex. Therefore ATP9A plays a crucial role in recycling from endosomes to the plasma membrane.
Collapse
Affiliation(s)
- Yoshiki Tanaka
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Natsuki Ono
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Takahiro Shima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Gaku Tanaka
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yohei Katoh
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hiroyuki Takatsu
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hye-Won Shin
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| |
Collapse
|
72
|
Abstract
Cellular membranes display a diversity of functions that are conferred by the unique composition and organization of their proteins and lipids. One important aspect of lipid organization is the asymmetric distribution of phospholipids (PLs) across the plasma membrane. The unequal distribution of key PLs between the cytofacial and exofacial leaflets of the bilayer creates physical surface tension that can be used to bend the membrane; and like Ca2+, a chemical gradient that can be used to transduce biochemical signals. PL flippases in the type IV P-type ATPase (P4-ATPase) family are the principle transporters used to set and repair this PL gradient and the asymmetric organization of these membranes are encoded by the substrate specificity of these enzymes. Thus, understanding the mechanisms of P4-ATPase substrate specificity will help reveal their role in membrane organization and cell biology. Further, decoding the structural determinants of substrate specificity provides investigators the opportunity to mutationally tune this specificity to explore the role of particular PL substrates in P4-ATPase cellular functions. This work reviews the role of P4-ATPases in membrane biology, presents our current understanding of P4-ATPase substrate specificity, and discusses how these fundamental aspects of P4-ATPase enzymology may be used to enhance our knowledge of cellular membrane biology.
Collapse
Affiliation(s)
- Bartholomew P. Roland
- Vanderbilt University, Department of Biological Sciences, 1161 21st Ave South, Nashville, TN 37235
| | - Todd R. Graham
- Vanderbilt University, Department of Biological Sciences, 1161 21st Ave South, Nashville, TN 37235
| |
Collapse
|
73
|
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.
Collapse
|
74
|
Assay of Flippase Activity in Proteoliposomes Using Fluorescent Lipid Derivatives. Methods Mol Biol 2016; 1377:181-91. [PMID: 26695033 DOI: 10.1007/978-1-4939-3179-8_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Specific membrane proteins, termed lipid flippases, play a central role in facilitating the movement of lipids across cellular membranes. In this protocol, we describe the reconstitution of ATP-driven lipid flippases in liposomes and the analysis of their in vitro flippase activity based on the use of fluorescent lipid derivatives. Working with purified and reconstituted systems provides a well-defined experimental setup and allows to directly characterize these membrane proteins at the molecular level.
Collapse
|
75
|
Pomorski TG, Menon AK. Lipid somersaults: Uncovering the mechanisms of protein-mediated lipid flipping. Prog Lipid Res 2016; 64:69-84. [PMID: 27528189 DOI: 10.1016/j.plipres.2016.08.003] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 08/10/2016] [Indexed: 12/22/2022]
Abstract
Membrane lipids diffuse rapidly in the plane of the membrane but their ability to flip spontaneously across a membrane bilayer is hampered by a significant energy barrier. Thus spontaneous flip-flop of polar lipids across membranes is very slow, even though it must occur rapidly to support diverse aspects of cellular life. Here we discuss the mechanisms by which rapid flip-flop occurs, and what role lipid flipping plays in membrane homeostasis and cell growth. We focus on conceptual aspects, highlighting mechanistic insights from biochemical and in silico experiments, and the recent, ground-breaking identification of a number of lipid scramblases.
Collapse
Affiliation(s)
- Thomas Günther Pomorski
- Faculty of Chemistry and Biochemistry, Molecular Biochemistry, Ruhr University Bochum, Universitätstrasse 150, D-44780 Bochum, Germany; Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.
| | - Anant K Menon
- Department of Biochemistry, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA.
| |
Collapse
|
76
|
de Waart DR, Naik J, Utsunomiya KS, Duijst S, Ho-Mok K, Bolier AR, Hiralall J, Bull LN, Bosma PJ, Oude Elferink RP, Paulusma CC. ATP11C targets basolateral bile salt transporter proteins in mouse central hepatocytes. Hepatology 2016; 64:161-74. [PMID: 26926206 PMCID: PMC5266587 DOI: 10.1002/hep.28522] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 02/25/2016] [Indexed: 12/16/2022]
Abstract
UNLABELLED ATP11C is a homolog of ATP8B1, both of which catalyze the transport of phospholipids in biological membranes. Mutations in ATP8B1 cause progressive familial intrahepatic cholestasis type1 in humans, which is characterized by a canalicular cholestasis. Mice deficient in ATP11C are characterized by a conjugated hyperbilirubinemia and an unconjugated hypercholanemia. Here, we have studied the hypothesis that ATP11C deficiency interferes with basolateral uptake of unconjugated bile salts, a process mediated by organic anion-transporting polypeptide (OATP) 1B2. ATP11C localized to the basolateral membrane of central hepatocytes in the liver lobule of control mice. In ATP11C-deficient mice, plasma total bilirubin levels were 6-fold increased, compared to control, of which ∼65% was conjugated and ∼35% unconjugated. Plasma total bile salts were 10-fold increased and were mostly present as unconjugated species. Functional studies in ATP11C-deficient mice indicated that hepatic uptake of unconjugated bile salts was strongly impaired whereas uptake of conjugated bile salts was unaffected. Western blotting and immunofluorescence analysis demonstrated near absence of basolateral bile salt uptake transporters OATP1B2, OATP1A1, OATP1A4, and Na(+) -taurocholate-cotransporting polypeptide only in central hepatocytes of ATP11C-deficient liver. In vivo application of the proteasome inhibitor, bortezomib, partially restored expression of these proteins, but not their localization. Furthermore, we observed post-translational down-regulation of ATP11C protein in livers from cholestatic mice, which coincided with reduced OATP1B2 levels. CONCLUSIONS ATP11C is essential for basolateral membrane localization of multiple bile salt transport proteins in central hepatocytes and may act as a gatekeeper to prevent hepatic bile salt overload. Conjugated hyperbilirubinemia and unconjugated hypercholanemia and loss of OATP expression in ATP11C-deficient liver strongly resemble the characteristics of Rotor syndrome, suggesting that mutations in ATP11C can predispose to Rotor syndrome. (Hepatology 2016;64:161-174).
Collapse
Affiliation(s)
- Dirk R. de Waart
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| | - Jyoti Naik
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| | | | - Suzanne Duijst
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| | - Kam Ho-Mok
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| | - A. Ruth Bolier
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| | - Johan Hiralall
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| | - Laura N. Bull
- Liver Center Laboratory, Department of Medicine, and Institute for Human Genetics, University of California San Francisco, San Francisco, CA
| | - Piter J. Bosma
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| | - Ronald P.J. Oude Elferink
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| | - Coen C. Paulusma
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| |
Collapse
|
77
|
Costa SR, Marek M, Axelsen KB, Theorin L, Pomorski TG, López-Marqués RL. Role of post-translational modifications at the β-subunit ectodomain in complex association with a promiscuous plant P4-ATPase. Biochem J 2016; 473:1605-15. [PMID: 27048590 PMCID: PMC4888458 DOI: 10.1042/bcj20160207] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 04/01/2016] [Accepted: 04/04/2016] [Indexed: 12/14/2022]
Abstract
P-type ATPases of subfamily IV (P4-ATPases) constitute a major group of phospholipid flippases that form heteromeric complexes with members of the Cdc50 (cell division control 50) protein family. Some P4-ATPases interact specifically with only one β-subunit isoform, whereas others are promiscuous and can interact with several isoforms. In the present study, we used a site-directed mutagenesis approach to assess the role of post-translational modifications at the plant ALIS5 β-subunit ectodomain in the functionality of the promiscuous plant P4-ATPase ALA2. We identified two N-glycosylated residues, Asn(181) and Asn(231) Whereas mutation of Asn(231) seems to have a small effect on P4-ATPase complex formation, mutation of evolutionarily conserved Asn(181) disrupts interaction between the two subunits. Of the four cysteine residues located in the ALIS5 ectodomain, mutation of Cys(86) and Cys(107) compromises complex association, but the mutant β-subunits still promote complex trafficking and activity to some extent. In contrast, disruption of a conserved disulfide bond between Cys(158) and Cys(172) has no effect on the P4-ATPase complex. Our results demonstrate that post-translational modifications in the β-subunit have different functional roles in different organisms, which may be related to the promiscuity of the P4-ATPase.
Collapse
Affiliation(s)
- Sara R Costa
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKin, University of Copenhagen, DK-1871, Frederiksberg C, Denmark
| | - Magdalena Marek
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKin, University of Copenhagen, DK-1871, Frederiksberg C, Denmark
| | - Kristian B Axelsen
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKin, University of Copenhagen, DK-1871, Frederiksberg C, Denmark SIB Swiss Institute of Bioinformatics, CMU, CH-1211, Geneva, Switzerland
| | - Lisa Theorin
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKin, University of Copenhagen, DK-1871, Frederiksberg C, Denmark
| | - Thomas G Pomorski
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKin, University of Copenhagen, DK-1871, Frederiksberg C, Denmark Faculty of Chemistry and Biochemistry, Department of Molecular Biochemistry, Ruhr University Bochum, Universitätstrasse 150, D-44780 Bochum, Germany
| | - Rosa L López-Marqués
- Department of Plant and Environmental Sciences, Centre for Membrane Pumps in Cells and Disease-PUMPKin, University of Copenhagen, DK-1871, Frederiksberg C, Denmark
| |
Collapse
|
78
|
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: 208] [Impact Index Per Article: 26.0] [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.
Collapse
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
| |
Collapse
|
79
|
Montigny C, Lyons J, Champeil P, Nissen P, Lenoir G. On the molecular mechanism of flippase- and scramblase-mediated phospholipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:767-783. [PMID: 26747647 DOI: 10.1016/j.bbalip.2015.12.020] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/20/2015] [Accepted: 12/28/2015] [Indexed: 11/20/2022]
Abstract
Phospholipid flippases are key regulators of transbilayer lipid asymmetry in eukaryotic cell membranes, critical to many trafficking and signaling pathways. P4-ATPases, in particular, are responsible for the uphill transport of phospholipids from the exoplasmic to the cytosolic leaflet of the plasma membrane, as well as membranes of the late secretory/endocytic pathways, thereby establishing transbilayer asymmetry. Recent studies combining cell biology and biochemical approaches have improved our understanding of the path taken by lipids through P4-ATPases. Additionally, identification of several protein families catalyzing phospholipid 'scrambling', i.e. disruption of phospholipid asymmetry through energy-independent bi-directional phospholipid transport, as well as the recent report of the structure of such a scramblase, opens the way to a deeper characterization of their mechanism of action. Here, we discuss the molecular nature of the mechanism by which lipids may 'flip' across membranes, with an emphasis on active lipid transport catalyzed by P4-ATPases. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
Collapse
Affiliation(s)
- Cédric Montigny
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Joseph Lyons
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Philippe Champeil
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Poul Nissen
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Guillaume Lenoir
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France.
| |
Collapse
|
80
|
Specific mutations in mammalian P4-ATPase ATP8A2 catalytic subunit entail differential glycosylation of the accessory CDC50A subunit. FEBS Lett 2015; 589:3908-14. [PMID: 26592152 DOI: 10.1016/j.febslet.2015.11.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 11/16/2015] [Accepted: 11/16/2015] [Indexed: 12/21/2022]
Abstract
P4-ATPases, or flippases, translocate phospholipids between the two leaflets of eukaryotic biological membranes. They are essential to the physiologically crucial phospholipid asymmetry and involved in severe diseases, but their molecular structure and mechanism are still unresolved. Here, we show that in an extensive mutational alanine screening of the mammalian flippase ATP8A2 catalytic subunit, five mutations stand out by leading to reduced glycosylation of the accessory subunit CDC50A. These mutations may disturb the interaction between the subunits.
Collapse
|
81
|
Segawa K, Kurata S, Nagata S. Human Type IV P-type ATPases That Work as Plasma Membrane Phospholipid Flippases and Their Regulation by Caspase and Calcium. J Biol Chem 2015; 291:762-72. [PMID: 26567335 DOI: 10.1074/jbc.m115.690727] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Indexed: 11/06/2022] Open
Abstract
In plasma membranes, flippases translocate aminophospholipids such as phosphatidylserine and phosphatidylethanolamine from the extracellular to the cytoplasmic leaflet. Mammalian ATP11C, a type IV P-type ATPase, acts as a flippase at the plasma membrane. Here, by expressing 12 human type IV P-type ATPases in ATP11C-deficient cells, we determined that ATP8A2 and ATP11A can also act as plasma membrane flippases. As with ATP11C, ATP8A2 and ATP11A localized to the plasma membrane in a CDC50A-dependent manner. ATP11A was cleaved by caspases during apoptosis, and a caspase-resistant ATP11A blocked apoptotic PtdSer exposure. In contrast, ATP8A2 was not cleaved by caspase, and cells expressing ATP8A2 did not expose PtdSer during apoptosis. Similarly, high Ca(2+) concentrations inhibited the ATP11A and ATP11C PtdSer flippase activity, but ATP8A2 flippase activity was relatively resistant to Ca(2+). ATP11A and ATP11C were ubiquitously expressed in human and mouse adult tissues. In contrast, ATP8A2 was expressed in specific tissues, such as the brain and testis. Thus, ATP8A2 may play a specific role in translocating PtdSer in these tissues.
Collapse
Affiliation(s)
- Katsumori Segawa
- From the Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - Sachiko Kurata
- From the Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| | - Shigekazu Nagata
- From the Laboratory of Biochemistry & Immunology, Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan
| |
Collapse
|
82
|
Takada N, Takatsu H, Miyano R, Nakayama K, Shin HW. ATP11C mutation is responsible for the defect in phosphatidylserine uptake in UPS-1 cells. J Lipid Res 2015; 56:2151-7. [PMID: 26420878 DOI: 10.1194/jlr.m062547] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Indexed: 12/24/2022] Open
Abstract
Type IV P-type ATPases (P4-ATPases) translocate phospholipids from the exoplasmic to the cytoplasmic leaflets of cellular membranes. We and others previously showed that ATP11C, a member of the P4-ATPases, translocates phosphatidylserine (PS) at the plasma membrane. Twenty years ago, the UPS-1 (uptake of fluorescent PS analogs) cell line was isolated from mutagenized Chinese hamster ovary (CHO)-K1 cells with a defect in nonendocytic uptake of nitrobenzoxadiazole PS. Due to its defect in PS uptake, the UPS-1 cell line has been used in an assay for PS-flipping activity; however, the gene(s) responsible for the defect have not been identified to date. Here, we found that the mRNA level of ATP11C was dramatically reduced in UPS-1 cells relative to parental CHO-K1 cells. By contrast, the level of ATP11A, another PS-flipping P4-ATPase at the plasma membrane, or CDC50A, which is essential for delivery of most P4-ATPases to the plasma membrane, was not affected in UPS-1 cells. Importantly, we identified a nonsense mutation in the ATP11C gene in UPS-1 cells, indicating that the intact ATP11C protein is not expressed. Moreover, exogenous expression of ATP11C can restore PS uptake in UPS-1 cells. These results indicate that lack of the functional ATP11C protein is responsible for the defect in PS uptake in UPS-1 cells and ATP11C is crucial for PS flipping in CHO-K1 cells.
Collapse
Affiliation(s)
- Naoto Takada
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku; Kyoto 606-8501, Japan
| | - Hiroyuki Takatsu
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku; Kyoto 606-8501, Japan
| | - Rie Miyano
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku; Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku; Kyoto 606-8501, Japan
| | - Hye-Won Shin
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku; Kyoto 606-8501, Japan
| |
Collapse
|
83
|
Ansari IUH, Longacre MJ, Paulusma CC, Stoker SW, Kendrick MA, MacDonald MJ. Characterization of P4 ATPase Phospholipid Translocases (Flippases) in Human and Rat Pancreatic Beta Cells: THEIR GENE SILENCING INHIBITS INSULIN SECRETION. J Biol Chem 2015; 290:23110-23. [PMID: 26240149 DOI: 10.1074/jbc.m115.655027] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Indexed: 01/08/2023] Open
Abstract
The negative charge of phosphatidylserine in lipid bilayers of secretory vesicles and plasma membranes couples the domains of positively charged amino acids of secretory vesicle SNARE proteins with similar domains of plasma membrane SNARE proteins enhancing fusion of the two membranes to promote exocytosis of the vesicle contents of secretory cells. Our recent study of insulin secretory granules (ISG) (MacDonald, M. J., Ade, L., Ntambi, J. M., Ansari, I. H., and Stoker, S. W. (2015) Characterization of phospholipids in insulin secretory granules in pancreatic beta cells and their changes with glucose stimulation. J. Biol. Chem. 290, 11075-11092) suggested that phosphatidylserine and other phospholipids, such as phosphatidylethanolamine, in ISG could play important roles in docking and fusion of ISG to the plasma membrane in the pancreatic beta cell during insulin exocytosis. P4 ATPase flippases translocate primarily phosphatidylserine and, to a lesser extent, phosphatidylethanolamine across the lipid bilayers of intracellular vesicles and plasma membranes to the cytosolic leaflets of these membranes. CDC50A is a protein that forms a heterodimer with P4 ATPases to enhance their translocase catalytic activity. We found that the predominant P4 ATPases in pure pancreatic beta cells and human and rat pancreatic islets were ATP8B1, ATP8B2, and ATP9A. ATP8B1 and CDC50A were highly concentrated in ISG. ATP9A was concentrated in plasma membrane. Gene silencing of individual P4 ATPases and CDC50A inhibited glucose-stimulated insulin release in pure beta cells and in human pancreatic islets. This is the first characterization of P4 ATPases in beta cells. The results support roles for P4 ATPases in translocating phosphatidylserine to the cytosolic leaflets of ISG and the plasma membrane to facilitate the docking and fusion of ISG to the plasma membrane during insulin exocytosis.
Collapse
Affiliation(s)
- Israr-ul H Ansari
- From the Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| | - Melissa J Longacre
- From the Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| | - Coen C Paulusma
- the Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, 1105 BK Amsterdam, The Netherlands
| | - Scott W Stoker
- From the Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| | - Mindy A Kendrick
- From the Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| | - Michael J MacDonald
- From the Childrens Diabetes Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706 and
| |
Collapse
|
84
|
Abstract
Parkinson's disease (PD) is a movement disorder due to the loss of dopaminergic (DA) neurons in the substantia nigra. Alpha-synuclein phosphorylation and α-synuclein inclusion (Lewy body) become a main contributor, but little is known about their formation mechanism. Here we used protein expression profiling of PD to construct a model of their signalling network from drsophila to human and nominate major nodes that regulate PD development. We found in this network that LK6, a serine/threonine protein kinase, plays a key role in promoting α-synuclein Ser129 phosphorylation by identification of LK6 knockout and overexpression. In vivo test was further confirmed that LK6 indeed enhances α-synuclein phosphorylation, accelerates the death of dopaminergic neurons, reduces the climbing ability and shortens the the life span of drosophila. Further, MAP kinase-interacting kinase 2a (Mnk2a), a human homolog of LK6, also been shown to make α-synuclein phosphorylation and leads to α-synuclein inclusion formation. On the mechanism, the phosphorylation mediated by LK6 and Mnk2a is controlled through ERK signal pathway by phorbolmyristate acetate (PMA) avtivation and PD98059 inhibition. Our findings establish pivotal role of Lk6 and Mnk2a in unprecedented signalling networks, may lead to new therapies preventing α-synuclein inclusion formation and neurodegeneration.
Collapse
|
85
|
Naito T, Takatsu H, Miyano R, Takada N, Nakayama K, Shin HW. Phospholipid Flippase ATP10A Translocates Phosphatidylcholine and Is Involved in Plasma Membrane Dynamics. J Biol Chem 2015; 290:15004-17. [PMID: 25947375 DOI: 10.1074/jbc.m115.655191] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Indexed: 11/06/2022] Open
Abstract
We showed previously that ATP11A and ATP11C have flippase activity toward aminophospholipids (phosphatidylserine (PS) and phosphatidylethanolamine (PE)) and ATP8B1 and that ATP8B2 have flippase activity toward phosphatidylcholine (PC) (Takatsu, H., Tanaka, G., Segawa, K., Suzuki, J., Nagata, S., Nakayama, K., and Shin, H. W. (2014) J. Biol. Chem. 289, 33543-33556). Here, we show that the localization of class 5 P4-ATPases to the plasma membrane (ATP10A and ATP10D) and late endosomes (ATP10B) requires an interaction with CDC50A. Moreover, exogenous expression of ATP10A, but not its ATPase-deficient mutant ATP10A(E203Q), dramatically increased PC flipping but not flipping of PS or PE. Depletion of CDC50A caused ATP10A to be retained at the endoplasmic reticulum instead of being delivered to the plasma membrane and abrogated the increased PC flipping activity observed by expression of ATP10A. These results demonstrate that ATP10A is delivered to the plasma membrane via its interaction with CDC50A and, specifically, flips PC at the plasma membrane. Importantly, expression of ATP10A, but not ATP10A(E203Q), dramatically altered the cell shape and decreased cell size. In addition, expression of ATP10A, but not ATP10A(E203Q), delayed cell adhesion and cell spreading onto the extracellular matrix. These results suggest that enhanced PC flipping activity due to exogenous ATP10A expression alters the lipid composition at the plasma membrane, which may in turn cause a delay in cell spreading and a change in cell morphology.
Collapse
Affiliation(s)
| | | | | | - Naoto Takada
- the Faculty of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | | | | |
Collapse
|
86
|
Panatala R, Hennrich H, Holthuis JCM. Inner workings and biological impact of phospholipid flippases. J Cell Sci 2015; 128:2021-32. [PMID: 25918123 DOI: 10.1242/jcs.102715] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The plasma membrane, trans-Golgi network and endosomal system of eukaryotic cells are populated with flippases that hydrolyze ATP to help establish asymmetric phospholipid distributions across the bilayer. Upholding phospholipid asymmetry is vital to a host of cellular processes, including membrane homeostasis, vesicle biogenesis, cell signaling, morphogenesis and migration. Consequently, defining the identity of flippases and their biological impact has been the subject of intense investigations. Recent work has revealed a remarkable degree of kinship between flippases and cation pumps. In this Commentary, we review emerging insights into how flippases work, how their activity is controlled according to cellular demands, and how disrupting flippase activity causes system failure of membrane function, culminating in membrane trafficking defects, aberrant signaling and disease.
Collapse
Affiliation(s)
- Radhakrishnan Panatala
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands Molecular Cell Biology Division, University of Osnabrück, 49076 Osnabrück, Germany
| | - Hanka Hennrich
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands
| | - Joost C M Holthuis
- Department of Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, Utrecht University, 3584 Utrecht, The Netherlands Molecular Cell Biology Division, University of Osnabrück, 49076 Osnabrück, Germany
| |
Collapse
|
87
|
P4-ATPases: lipid flippases in cell membranes. Pflugers Arch 2015; 466:1227-40. [PMID: 24077738 PMCID: PMC4062807 DOI: 10.1007/s00424-013-1363-4] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 09/11/2013] [Accepted: 09/11/2013] [Indexed: 12/13/2022]
Abstract
Cellular membranes, notably eukaryotic plasma membranes, are equipped with special proteins that actively translocate lipids from one leaflet to the other and thereby help generate membrane lipid asymmetry. Among these ATP-driven transporters, the P4 subfamily of P-type ATPases (P4-ATPases) comprises lipid flippases that catalyze the translocation of phospholipids from the exoplasmic to the cytosolic leaflet of cell membranes. While initially characterized as aminophospholipid translocases, recent studies of individual P4-ATPase family members from fungi, plants, and animals show that P4-ATPases differ in their substrate specificities and mediate transport of a broader range of lipid substrates, including lysophospholipids and synthetic alkylphospholipids. At the same time, the cellular processes known to be directly or indirectly affected by this class of transporters have expanded to include the regulation of membrane traffic, cytoskeletal dynamics, cell division, lipid metabolism, and lipid signaling. In this review, we will summarize the basic features of P4-ATPases and the physiological implications of their lipid transport activity in the cell.
Collapse
|
88
|
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: 99] [Impact Index Per Article: 11.0] [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.
Collapse
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
| |
Collapse
|
89
|
Azouaoui H, Montigny C, Ash MR, Fijalkowski F, Jacquot A, Grønberg C, López-Marqués RL, Palmgren MG, Garrigos M, le Maire M, Decottignies P, Gourdon P, Nissen P, Champeil P, Lenoir G. A high-yield co-expression system for the purification of an intact Drs2p-Cdc50p lipid flippase complex, critically dependent on and stabilized by phosphatidylinositol-4-phosphate. PLoS One 2014; 9:e112176. [PMID: 25393116 PMCID: PMC4230938 DOI: 10.1371/journal.pone.0112176] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/13/2014] [Indexed: 01/01/2023] Open
Abstract
P-type ATPases from the P4 subfamily (P4-ATPases) are energy-dependent transporters, which are thought to establish lipid asymmetry in eukaryotic cell membranes. Together with their Cdc50 accessory subunits, P4-ATPases couple ATP hydrolysis to lipid transport from the exoplasmic to the cytoplasmic leaflet of plasma membranes, late Golgi membranes, and endosomes. To gain insights into the structure and function of these important membrane pumps, robust protocols for expression and purification are required. In this report, we present a procedure for high-yield co-expression of a yeast flippase, the Drs2p-Cdc50p complex. After recovery of yeast membranes expressing both proteins, efficient purification was achieved in a single step by affinity chromatography on streptavidin beads, yielding ∼1–2 mg purified Drs2p-Cdc50p complex per liter of culture. Importantly, the procedure enabled us to recover a fraction that mainly contained a 1∶1 complex, which was assessed by size-exclusion chromatography and mass spectrometry. The functional properties of the purified complex were examined, including the dependence of its catalytic cycle on specific lipids. The dephosphorylation rate was stimulated in the simultaneous presence of the transported substrate, phosphatidylserine (PS), and the regulatory lipid phosphatidylinositol-4-phosphate (PI4P), a phosphoinositide that plays critical roles in membrane trafficking events from the trans-Golgi network (TGN). Likewise, overall ATP hydrolysis by the complex was critically dependent on the simultaneous presence of PI4P and PS. We also identified a prominent role for PI4P in stabilization of the Drs2p-Cdc50p complex towards temperature- or C12E8-induced irreversible inactivation. These results indicate that the Drs2p-Cdc50p complex remains functional after affinity purification and that PI4P as a cofactor tightly controls its stability and catalytic activity. This work offers appealing perspectives for detailed structural and functional characterization of the Drs2p-Cdc50p lipid transport mechanism.
Collapse
Affiliation(s)
- Hassina Azouaoui
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Cédric Montigny
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Miriam-Rose Ash
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Frank Fijalkowski
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Aurore Jacquot
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Christina Grønberg
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Rosa L. López-Marqués
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael G. Palmgren
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Manuel Garrigos
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Marc le Maire
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Paulette Decottignies
- CNRS, Institut de Biochimie et Biophysique Moléculaire et Cellulaire, UMR 8619, Orsay, France
- Univ Paris-Sud, Orsay, France
| | - Pontus Gourdon
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Poul Nissen
- Centre for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Philippe Champeil
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
| | - Guillaume Lenoir
- Univ Paris-Sud, UMR 8221, Orsay, France
- CEA, iBiTec-S (Institut de Biologie et de Technologies de Saclay), SBSM (Service de Bioénergétique, Biologie Structurale et Mécanismes), Laboratoire des Protéines Membranaires, Gif-sur-Yvette, France
- CNRS, UMR 8221, Gif-sur-Yvette, France
- * E-mail:
| |
Collapse
|
90
|
Takatsu H, Tanaka G, Segawa K, Suzuki J, Nagata S, Nakayama K, Shin HW. Phospholipid flippase activities and substrate specificities of human type IV P-type ATPases localized to the plasma membrane. J Biol Chem 2014; 289:33543-56. [PMID: 25315773 DOI: 10.1074/jbc.m114.593012] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Type IV P-type ATPases (P4-ATPases) are believed to translocate aminophospholipids from the exoplasmic to the cytoplasmic leaflets of cellular membranes. The yeast P4-ATPases, Drs2p and Dnf1p/Dnf2p, flip nitrobenzoxadiazole-labeled phosphatidylserine at the Golgi complex and nitrobenzoxadiazole-labeled phosphatidylcholine (PC) at the plasma membrane, respectively. However, the flippase activities and substrate specificities of mammalian P4-ATPases remain incompletely characterized. In this study, we established an assay for phospholipid flippase activities of plasma membrane-localized P4-ATPases using human cell lines stably expressing ATP8B1, ATP8B2, ATP11A, and ATP11C. We found that ATP11A and ATP11C have flippase activities toward phosphatidylserine and phosphatidylethanolamine but not PC or sphingomyelin. By contrast, ATPase-deficient mutants of ATP11A and ATP11C did not exhibit any flippase activity, indicating that these enzymes catalyze flipping in an ATPase-dependent manner. Furthermore, ATP8B1 and ATP8B2 exhibited preferential flippase activities toward PC. Some ATP8B1 mutants found in patients of progressive familial intrahepatic cholestasis type 1 (PFIC1), a severe liver disease caused by impaired bile flow, failed to translocate PC despite their delivery to the plasma membrane. Moreover, incorporation of PC mediated by ATP8B1 can be reversed by simultaneous expression of ABCB4, a PC floppase mutated in PFIC3 patients. Our findings elucidate the flippase activities and substrate specificities of plasma membrane-localized human P4-ATPases and suggest that phenotypes of some PFIC1 patients result from impairment of the PC flippase activity of ATP8B1.
Collapse
Affiliation(s)
- Hiroyuki Takatsu
- From the Career-path Promotion Unit for Young Life Scientists and Graduate Schools of Pharmaceutical Sciences and
| | - Gaku Tanaka
- Graduate Schools of Pharmaceutical Sciences and
| | | | - Jun Suzuki
- Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | | | | | - Hye-Won Shin
- From the Career-path Promotion Unit for Young Life Scientists and Graduate Schools of Pharmaceutical Sciences and
| |
Collapse
|
91
|
Functional role of evolutionarily highly conserved residues, N-glycosylation level and domains of the Leishmania miltefosine transporter-Cdc50 subunit. Biochem J 2014; 459:83-94. [PMID: 24447089 DOI: 10.1042/bj20131318] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Cdc50 (cell-cycle control protein 50) is a family of conserved eukaryotic proteins that interact with P4-ATPases (phospholipid translocases). Cdc50 association is essential for the endoplasmic reticulum export of P4-ATPases and proper translocase activity. In the present study, we analysed the role of Leishmania infantum LiRos3, the Cdc50 subunit of the P4-ATPase MLF (miltefosine) transporter [LiMT (L. infantum MLF transporter)], on trafficking and complex functionality using site-directed mutagenesis and domain substitution. We identified 22 invariant residues in the Cdc50 proteins from L. infantum, human and yeast. Seven of these residues are found in the extracellular domain of LiRos3, the conservation of which is critical for ensuring that LiMT arrives at the plasma membrane. The substitution of other invariant residues affects complex trafficking to a lesser extent. Furthermore, invariant residues located in the N-terminal cytosolic domain play a role in the transport activity. Partial N-glycosylation of LiRos3 reduces MLF transport and total N-deglycosylation completely inhibits LiMT trafficking to the plasma membrane. One of the N-glycosylation residues is invariant along the Cdc50 family. The transmembrane and exoplasmic domains are not interchangeable with the other two L. infantum Cdc50 proteins to maintain LiMT interaction. Taken together, these findings indicate that both invariant and N-glycosylated residues of LiRos3 are implicated in LiMT trafficking and transport activity.
Collapse
|
92
|
Structure and mechanism of ATP-dependent phospholipid transporters. Biochim Biophys Acta Gen Subj 2014; 1850:461-75. [PMID: 24746984 DOI: 10.1016/j.bbagen.2014.04.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 04/04/2014] [Accepted: 04/07/2014] [Indexed: 01/09/2023]
Abstract
BACKGROUND ATP-binding cassette (ABC) transporters and P4-ATPases are two large and seemingly unrelated families of primary active pumps involved in moving phospholipids from one leaflet of a biological membrane to the other. SCOPE OF REVIEW This review aims to identify common mechanistic features in the way phospholipid flipping is carried out by two evolutionarily unrelated families of transporters. MAJOR CONCLUSIONS Both protein families hydrolyze ATP, although they employ different mechanisms to use it, and have a comparable size with twelve transmembrane segments in the functional unit. Further, despite differences in overall architecture, both appear to operate by an alternating access mechanism and during transport they might allow access of phospholipids to the internal part of the transmembrane domain. The latter feature is obvious for ABC transporters, but phospholipids and other hydrophobic molecules have also been found embedded in P-type ATPase crystal structures. Taken together, in two diverse groups of pumps, nature appears to have evolved quite similar ways of flipping phospholipids. GENERAL SIGNIFICANCE Our understanding of the structural basis for phospholipid flipping is still limited but it seems plausible that a general mechanism for phospholipid flipping exists in nature. This article is part of a Special Issue entitled Structural biochemistry and biophysics of membrane proteins.
Collapse
|
93
|
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: 88] [Impact Index Per Article: 8.8] [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.
Collapse
|
94
|
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.
Collapse
Affiliation(s)
- Jonathan A Coleman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | | | | | | | | | | | | | | |
Collapse
|
95
|
Molday LL, Molday RS. 1D4: a versatile epitope tag for the purification and characterization of expressed membrane and soluble proteins. Methods Mol Biol 2014; 1177:1-15. [PMID: 24943310 DOI: 10.1007/978-1-4939-1034-2_1] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Incorporation of short epitope tags into proteins for recognition by commercially available monoclonal or polyclonal antibodies has greatly facilitated the detection, characterization, localization, and purification of heterologously expressed proteins for structure-function studies. A number of tags have been developed, but many epitope-antibody combinations do not work effectively for all immunochemical techniques due to the nature of the tag and the specificity of the antibodies. A highly versatile, multipurpose epitope tag is the 9 amino acid C-terminal 1D4 peptide. This peptide tag together with the Rho1D4 monoclonal antibody can be used to detect proteins in complex mixtures by western blotting and ELISA assays, localize proteins in cells by immunofluorescence and immunoelectron microscopic labeling techniques, identify subunits and interacting proteins by co-immunoprecipitation, and purify functionally active proteins including membrane proteins by immunoaffinity chromatography. In this chapter we describe various immunochemical procedures which can be used for the detection, purification and localization of 1D4-tagged proteins for structure-function studies.
Collapse
Affiliation(s)
- Laurie L Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada, V6T 1Z3
| | | |
Collapse
|
96
|
Skiba NP, Spencer WJ, Salinas RY, Lieu EC, Thompson JW, Arshavsky VY. Proteomic identification of unique photoreceptor disc components reveals the presence of PRCD, a protein linked to retinal degeneration. J Proteome Res 2013; 12:3010-8. [PMID: 23672200 DOI: 10.1021/pr4003678] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Visual signal transduction takes place on the surface of flat membrane vesicles called photoreceptor discs, which reside inside the light-sensitive outer segment organelle of vertebrate photoreceptor cells. Although biochemical studies have indicated that discs are built with a handful of highly specialized proteins, proteomic studies have yielded databases consisting of hundreds of entries. We addressed this controversy by employing protein correlation profiling, which allows identification of unique components of organelles that can be fractionated but not purified to absolute homogeneity. We subjected discs to sequential steps of fractionation and identified the relative amounts of proteins in each fraction by label-free quantitative mass spectrometry. This analysis demonstrated that the photoreceptor disc proteome contains only eleven components, which satisfy the hallmark criterion for being unique disc-resident components: the retention of a constant molar ratio among themselves across fractionation steps. Remarkably, one of them is PRCD, a protein whose mutations have been shown to cause blindness, yet cellular localization remained completely unknown. Identification of PRCD as a novel disc-specific protein facilitates understanding its functional role and the pathobiological significance of its mutations. Our study provides a striking example how protein correlation profiling allows a distinction between constitutive components of cellular organelles and their inevitable contaminants.
Collapse
Affiliation(s)
- Nikolai P Skiba
- Albert Eye Research Institute, 2Institute for Genome Sciences & Policy, Duke University School of Medicine, Durham, North Carolina 27710, United States
| | | | | | | | | | | |
Collapse
|
97
|
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: 97] [Impact Index Per Article: 8.8] [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.
Collapse
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.
| | | | | |
Collapse
|
98
|
Abstract
Photoreceptors are exquisitely adapted to transform light stimuli into electrical signals that modulate neurotransmitter release. These cells are organized into several compartments including the unique outer segment (OS). Its whole function is to absorb light and transduce this signal into a change of membrane potential. Another compartment is the inner segment where much of metabolism and regulation of membrane potential takes place and that connects the OS and synapse. The synapse is the compartment where changes in membrane potentials are relayed to other neurons in the retina via release of neurotransmitter. The composition of the plasma membrane surrounding these compartments varies to accommodate their specific functions. In this chapter, we discuss the organization of the plasma membrane emphasizing the protein composition of each region as it relates to visual signaling. We also point out examples where mutations in these proteins cause visual impairment.
Collapse
Affiliation(s)
- Sheila A Baker
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
| | | |
Collapse
|
99
|
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.
Collapse
Affiliation(s)
- Utako Kato
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | | | | | | | | | | |
Collapse
|
100
|
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: 107] [Impact Index Per Article: 8.9] [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.
Collapse
Affiliation(s)
- Jonathan A Coleman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
| | | | | |
Collapse
|