1
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Belot A, Puy H, Hamza I, Bonkovsky HL. Update on heme biosynthesis, tissue-specific regulation, heme transport, relation to iron metabolism and cellular energy. Liver Int 2024; 44:2235-2250. [PMID: 38888238 DOI: 10.1111/liv.15965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/19/2024] [Accepted: 04/23/2024] [Indexed: 06/20/2024]
Abstract
Heme is a primordial macrocycle upon which most aerobic life on Earth depends. It is essential to the survival and health of nearly all cells, functioning as a prosthetic group for oxygen-carrying proteins and enzymes involved in oxidation/reduction and electron transport reactions. Heme is essential for the function of numerous hemoproteins and has numerous other roles in the biochemistry of life. In mammals, heme is synthesised from glycine, succinyl-CoA, and ferrous iron in a series of eight steps. The first and normally rate-controlling step is catalysed by 5-aminolevulinate synthase (ALAS), which has two forms: ALAS1 is the housekeeping form with highly variable expression, depending upon the supply of the end-product heme, which acts to repress its activity; ALAS2 is the erythroid form, which is regulated chiefly by the adequacy of iron for erythroid haemoglobin synthesis. Abnormalities in the several enzymes of the heme synthetic pathway, most of which are inherited partial enzyme deficiencies, give rise to rare diseases called porphyrias. The existence and role of heme importers and exporters in mammals have been debated. Recent evidence established the presence of heme transporters. Such transporters are important for the transfer of heme from mitochondria, where the penultimate and ultimate steps of heme synthesis occur, and for the transfer of heme from cytoplasm to other cellular organelles. Several chaperones of heme and iron are known and important for cell health. Heme and iron, although promoters of oxidative stress and potentially toxic, are essential cofactors for cellular energy production and oxygenation.
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Affiliation(s)
- Audrey Belot
- Center for Blood Oxygen Transport and Hemostasis, Department of Pediatrics, School of Medicine, University of Maryland, Baltimore, Maryland, USA
| | - Herve Puy
- Centre Français des Porphyries, Assistance Publique-Hôpitaux de Paris (APHP), Université de Paris Cité, INSERM U1149, Paris, France
| | - Iqbal Hamza
- Center for Blood Oxygen Transport and Hemostasis, Department of Pediatrics, School of Medicine, University of Maryland, Baltimore, Maryland, USA
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, USA
| | - Herbert L Bonkovsky
- Section on Gastroenterology & Hepatology, Department of Medicine, Wake Forest University School of Medicine, Atrium Health Wake Forest Baptist, Winston-Salem, North Carolina, USA
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2
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Ri K, Weng TH, Claveras Cabezudo A, Jösting W, Zhang Y, Bazzone A, Leong NCP, Welsch S, Doty RT, Gursu G, Lim TJY, Schmidt SL, Abkowitz JL, Hummer G, Wu D, Nguyen LN, Safarian S. Molecular mechanism of choline and ethanolamine transport in humans. Nature 2024; 630:501-508. [PMID: 38778100 PMCID: PMC11168923 DOI: 10.1038/s41586-024-07444-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 04/19/2024] [Indexed: 05/25/2024]
Abstract
Human feline leukaemia virus subgroup C receptor-related proteins 1 and 2 (FLVCR1 and FLVCR2) are members of the major facilitator superfamily1. Their dysfunction is linked to several clinical disorders, including PCARP, HSAN and Fowler syndrome2-7. Earlier studies concluded that FLVCR1 may function as a haem exporter8-12, whereas FLVCR2 was suggested to act as a haem importer13, yet conclusive biochemical and detailed molecular evidence remained elusive for the function of both transporters14-16. Here, we show that FLVCR1 and FLVCR2 facilitate the transport of choline and ethanolamine across the plasma membrane, using a concentration-driven substrate translocation process. Through structural and computational analyses, we have identified distinct conformational states of FLVCRs and unravelled the coordination chemistry underlying their substrate interactions. Fully conserved tryptophan and tyrosine residues form the binding pocket of both transporters and confer selectivity for choline and ethanolamine through cation-π interactions. Our findings clarify the mechanisms of choline and ethanolamine transport by FLVCR1 and FLVCR2, enhance our comprehension of disease-associated mutations that interfere with these vital processes and shed light on the conformational dynamics of these major facilitator superfamily proteins during the transport cycle.
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Affiliation(s)
- Keiken Ri
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Program, Life Sciences Institute, National University of Singapore, Singapore, Singapore
- Singapore Lipidomics Incubator (SLING), Life Sciences Institute, National University of Singapore, Singapore, Singapore
- Cardiovascular Disease Research (CVD) Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Tsai-Hsuan Weng
- Department and Emeritus Group of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Ainara Claveras Cabezudo
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany
- IMPRS on Cellular Biophysics, Frankfurt, Germany
| | - Wiebke Jösting
- Department and Emeritus Group of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Yu Zhang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | | | - Nancy C P Leong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Program, Life Sciences Institute, National University of Singapore, Singapore, Singapore
- Singapore Lipidomics Incubator (SLING), Life Sciences Institute, National University of Singapore, Singapore, Singapore
- Cardiovascular Disease Research (CVD) Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Sonja Welsch
- Central Electron Microscopy Facility, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Raymond T Doty
- Division of Hematology, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Gonca Gursu
- Department and Emeritus Group of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Tiffany Jia Ying Lim
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Program, Life Sciences Institute, National University of Singapore, Singapore, Singapore
- Singapore Lipidomics Incubator (SLING), Life Sciences Institute, National University of Singapore, Singapore, Singapore
- Cardiovascular Disease Research (CVD) Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Immunology Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Sarah Luise Schmidt
- Department and Emeritus Group of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Janis L Abkowitz
- Division of Hematology, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt, Germany.
- Institute of Biophysics, Goethe University Frankfurt, Frankfurt, Germany.
| | - Di Wu
- Department and Emeritus Group of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany.
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Frankfurt, Germany.
| | - Long N Nguyen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
- Immunology Program, Life Sciences Institute, National University of Singapore, Singapore, Singapore.
- Singapore Lipidomics Incubator (SLING), Life Sciences Institute, National University of Singapore, Singapore, Singapore.
- Cardiovascular Disease Research (CVD) Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
- Immunology Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
| | - Schara Safarian
- Department and Emeritus Group of Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt, Germany.
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Frankfurt, Germany.
- Institute of Clinical Pharmacology, Faculty of Medicine, Goethe University Frankfurt, Frankfurt, Germany.
- Fraunhofer Cluster of Excellence for Immune Mediated Diseases (CIMD), Frankfurt, Germany.
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3
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Cater RJ, Mukherjee D, Gil-Iturbe E, Erramilli SK, Chen T, Koo K, Santander N, Reckers A, Kloss B, Gawda T, Choy BC, Zhang Z, Katewa A, Larpthaveesarp A, Huang EJ, Mooney SWJ, Clarke OB, Yee SW, Giacomini KM, Kossiakoff AA, Quick M, Arnold T, Mancia F. Structural and molecular basis of choline uptake into the brain by FLVCR2. Nature 2024; 629:704-709. [PMID: 38693257 PMCID: PMC11168207 DOI: 10.1038/s41586-024-07326-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 03/15/2024] [Indexed: 05/03/2024]
Abstract
Choline is an essential nutrient that the human body needs in vast quantities for cell membrane synthesis, epigenetic modification and neurotransmission. The brain has a particularly high demand for choline, but how it enters the brain remains unknown1-3. The major facilitator superfamily transporter FLVCR1 (also known as MFSD7B or SLC49A1) was recently determined to be a choline transporter but is not highly expressed at the blood-brain barrier, whereas the related protein FLVCR2 (also known as MFSD7C or SLC49A2) is expressed in endothelial cells at the blood-brain barrier4-7. Previous studies have shown that mutations in human Flvcr2 cause cerebral vascular abnormalities, hydrocephalus and embryonic lethality, but the physiological role of FLVCR2 is unknown4,5. Here we demonstrate both in vivo and in vitro that FLVCR2 is a BBB choline transporter and is responsible for the majority of choline uptake into the brain. We also determine the structures of choline-bound FLVCR2 in both inward-facing and outward-facing states using cryo-electron microscopy. These results reveal how the brain obtains choline and provide molecular-level insights into how FLVCR2 binds choline in an aromatic cage and mediates its uptake. Our work could provide a novel framework for the targeted delivery of therapeutic agents into the brain.
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Affiliation(s)
- Rosemary J Cater
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA.
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia.
| | - Dibyanti Mukherjee
- Department of Pediatrics, Neonatal Brain Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Eva Gil-Iturbe
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, USA
| | - Satchal K Erramilli
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Ting Chen
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Katie Koo
- Department of Pediatrics, Neonatal Brain Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Nicolás Santander
- Instituto de Ciencias de la Salud, Universidad de O'Higgins, Rancagua, Chile
| | - Andrew Reckers
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Brian Kloss
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Tomasz Gawda
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Brendon C Choy
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Zhening Zhang
- Cryo-Electron Microscopy Center, Columbia University, New York, NY, USA
| | - Aditya Katewa
- Department of Pediatrics, Neonatal Brain Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Amara Larpthaveesarp
- Department of Pediatrics, Neonatal Brain Research Institute, University of California San Francisco, San Francisco, CA, USA
| | - Eric J Huang
- Department of Pathology, University of California, San Francisco, San Francisco, CA, USA
- Pathology Service, San Francisco VA Medical Center, San Francisco, CA, USA
| | | | - Oliver B Clarke
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
- Department of Anesthesiology, Columbia University Irving Medical Center, New York, NY, USA
| | - Sook Wah Yee
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA, USA
| | - Kathleen M Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Matthias Quick
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
- Department of Psychiatry, Columbia University Irving Medical Center, New York, NY, USA
- New York State Psychiatric Institute, Area Neuroscience-Molecular Therapeutics, New York, NY, USA
| | - Thomas Arnold
- Department of Pediatrics, Neonatal Brain Research Institute, University of California San Francisco, San Francisco, CA, USA.
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA.
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4
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Nguyen XTA, Le TNU, Nguyen TQ, Thi Thuy Ha H, Artati A, Leong NCP, Nguyen DT, Lim PY, Susanto AV, Huang Q, Fam L, Leong LN, Bonne I, Lee A, Granadillo JL, Gooch C, Yu D, Huang H, Soong TW, Chang MW, Wenk MR, Adamski J, Cazenave-Gassiot A, Nguyen LN. MFSD7c functions as a transporter of choline at the blood-brain barrier. Cell Res 2024; 34:245-257. [PMID: 38302740 PMCID: PMC10907603 DOI: 10.1038/s41422-023-00923-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Accepted: 12/26/2023] [Indexed: 02/03/2024] Open
Abstract
Mutations in the orphan transporter MFSD7c (also known as Flvcr2), are linked to Fowler syndrome. Here, we used Mfsd7c knockout (Mfsd7c-/-) mice and cell-based assays to reveal that MFSD7c is a choline transporter at the blood-brain barrier (BBB). We performed comprehensive metabolomics analysis and detected differential changes of metabolites in the brains and livers of Mfsd7c-/-embryos. Particularly, we found that choline-related metabolites were altered in the brains but not in the livers of Mfsd7c-/- embryos. Thus, we hypothesized that MFSD7c regulates the level of choline in the brain. Indeed, expression of human MFSD7c in cells significantly increased choline uptake. Interestingly, we showed that choline uptake by MFSD7c is greatly increased by choline-metabolizing enzymes, leading us to demonstrate that MFSD7c is a facilitative transporter of choline. Furthermore, single-cell patch clamp analysis showed that the import of choline by MFSD7c is electrogenic. Choline transport function of MFSD7c was shown to be conserved in vertebrates, but not in yeasts. We demonstrated that human MFSD7c is a functional ortholog of HNM1, the yeast choline importer. We also showed that several missense mutations identified in patients exhibiting Fowler syndrome had abolished or reduced choline transport activity. Mice lacking Mfsd7c in endothelial cells of the central nervous system suppressed the import of exogenous choline from blood but unexpectedly had increased choline levels in the brain. Stable-isotope tracing study revealed that MFSD7c was required for exporting choline derived from lysophosphatidylcholine in the brain. Collectively, our work identifies MFSD7c as a choline exporter at the BBB and provides a foundation for future work to reveal the disease mechanisms of Fowler syndrome.
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Affiliation(s)
- Xuan Thi Anh Nguyen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Thanh Nha Uyen Le
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Hudson Institute of Medical Research, Clayton, VIC, Australia
| | - Toan Q Nguyen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Hoa Thi Thuy Ha
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Anna Artati
- Metabolomics and Proteomics Core, Helmholtz Center Munich, German Research Center for Environmental Health, Neuherberg, Germany
| | - Nancy C P Leong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Dat T Nguyen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Pei Yen Lim
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Singapore Lipidomics Incubator (SLING), Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Adelia Vicanatalita Susanto
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of Singapore, Singapore, Singapore
- Synthetic Biology Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Qianhui Huang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Ling Fam
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Lo Ngah Leong
- Electron Microscopy Unit, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Isabelle Bonne
- Electron Microscopy Unit, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Microbiology and Immunology, Immunology Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Life Sciences Institute, Immunology Programme, National University of Singapore, Singapore, Singapore
| | - Angela Lee
- Division of Genetics and Genomic Medicine, Department of Pediatrics, Washington University in St Louis, Saint Louis, MO, USA
| | - Jorge L Granadillo
- Division of Genetics and Genomic Medicine, Department of Pediatrics, Washington University in St Louis, Saint Louis, MO, USA
| | - Catherine Gooch
- Division of Genetics and Genomic Medicine, Department of Pediatrics, Washington University in St Louis, Saint Louis, MO, USA
| | - Dejie Yu
- Electrophysiology Core Facility, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Hua Huang
- Electrophysiology Core Facility, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Cardiovascular Diseases Program, National University of Singapore, Singapore, Singapore
| | - Tuck Wah Soong
- Electrophysiology Core Facility, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Cardiovascular Diseases Program, National University of Singapore, Singapore, Singapore
| | - Matthew Wook Chang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- NUS Synthetic Biology for Clinical and Technological Innovation (SynCTI), National University of Singapore, Singapore, Singapore
- Synthetic Biology Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Markus R Wenk
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Singapore Lipidomics Incubator (SLING), Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Jerzy Adamski
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Amaury Cazenave-Gassiot
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Singapore Lipidomics Incubator (SLING), Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Long N Nguyen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
- Singapore Lipidomics Incubator (SLING), Life Sciences Institute, National University of Singapore, Singapore, Singapore.
- Life Sciences Institute, Immunology Programme, National University of Singapore, Singapore, Singapore.
- Cardiovascular Diseases Program, National University of Singapore, Singapore, Singapore.
- Immunology Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
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5
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Heide M, Huttner WB. Causes of microcephaly in human-theoretical considerations. Front Neurosci 2023; 17:1306166. [PMID: 38075281 PMCID: PMC10701273 DOI: 10.3389/fnins.2023.1306166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 11/07/2023] [Indexed: 12/26/2023] Open
Abstract
As is evident from the theme of the Research Topic “Small Size, Big Problem: Understanding the Molecular Orchestra of Brain Development from Microcephaly,” the pathomechanisms leading to mirocephaly in human are at best partially understood. As molecular cell biologists and developmental neurobiologists, we present here a treatise with theoretical considerations that systematically dissect possible causes of microcephaly, which we believe is timely. Our considerations address the cell types affected in microcephaly, that is, the cortical stem and progenitor cells as well as the neurons and macroglial cell generated therefrom. We discuss issues such as progenitor cell types, cell lineages, modes of cell division, cell proliferation and cell survival. We support our theoretical considerations by discussing selected examples of factual cases of microcephaly, in order to point out that there is a much larger range of possible pathomechanisms leading to microcephaly in human than currently known.
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Affiliation(s)
- Michael Heide
- German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany
| | - Wieland B. Huttner
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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6
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Cater RJ, Mukherjee D, Iturbe EG, Erramilli SK, Chen T, Koo K, Grez NS, Reckers A, Kloss B, Gawda T, Choy BC, Zheng Z, Clarke OB, Yee SW, Kossiakoff AA, Quick M, Arnold T, Mancia F. Structural and molecular basis of choline uptake into the brain by FLVCR2. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.05.561059. [PMID: 37873173 PMCID: PMC10592973 DOI: 10.1101/2023.10.05.561059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Choline is an essential nutrient that the human body needs in vast quantities for cell membrane synthesis, epigenetic modification, and neurotransmission. The brain has a particularly high demand for choline, but how it enters the brain has eluded the field for over fifty years. The MFS transporter FLVCR1 was recently determined to be a choline transporter, and while this protein is not highly expressed at the blood-brain barrier (BBB), its relative FLVCR2 is. Previous studies have shown that mutations in human Flvcr2 cause cerebral vascular abnormalities, hydrocephalus, and embryonic lethality, but the physiological role of FLVCR2 is unknown. Here, we demonstrate both in vivo and in vitro that FLVCR2 is a BBB choline transporter and is responsible for the majority of choline uptake into the brain. We also determine the structures of choline-bound FLVCR2 in the inward- and outward-facing states using cryo-electron microscopy to 2.49 and 2.77 Å resolution, respectively. These results reveal how the brain obtains choline and provide molecular-level insights into how FLVCR2 binds choline in an aromatic cage and mediates its uptake. Our work could provide a novel framework for the targeted delivery of neurotherapeutics into the brain.
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7
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Ravindran E, Ullah N, Mani S, Chew EGY, Tandiono M, Foo JN, Khor CC, Kaindl AM, Siddiqi S. Case report: Expanding the phenotype of ARHGEF17 mutations from increased intracranial aneurysm risk to a neurodevelopmental disease. Front Neurol 2022; 13:1017654. [PMID: 36341116 PMCID: PMC9630465 DOI: 10.3389/fneur.2022.1017654] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 09/30/2022] [Indexed: 01/11/2024] Open
Abstract
RhoGTPase regulators play a key role in the development of the nervous system, and their dysfunction can result in brain malformation and associated disorders. Several guanine nucleotide exchange factors (GEF) have been linked to neurodevelopmental disorders. In line with this, ARHGEF17 has been recently linked as a risk gene to intracranial aneurysms. Here we report siblings of a consanguineous Pakistani family with biallelic variants in the ARHGEF17 gene associated with a neurodevelopmental disorder with intellectual disability, speech delay and motor dysfunction but not aneurysms. Cranial MRI performed in one patient revealed generalized brain atrophy with an enlarged ventricular system, thin corpus callosum and microcephaly. Whole exome sequencing followed by Sanger sequencing in two of the affected individuals revealed a homozygous missense variant (g.11:73021307, c.1624C>T (NM_014786.4), p.R542W) in the ARHGEF17 gene. This variant is in a highly conserved DCLK1 phosphorylation consensus site (I/L/V/F/M]RRXX[pS/pT][I/L/M/V/F) of the protein. Our report expands the phenotypic spectrum of ARHGEF17 variants from increased intracranial aneurysm risk to neurodevelopmental disease and thereby add ARHGEF17 to the list of GEF genes involved in neurodevelopmental disorders.
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Affiliation(s)
- Ethiraj Ravindran
- Charité–Universitätsmedizin Berlin, Institute of Cell Biology and Neurobiology, Berlin, Germany
- Charité–Universitätsmedizin Berlin, Department of Pediatric Neurology, Berlin, Germany
- Charité–Universitätsmedizin Berlin, Center for Chronically Sick Children (Sozialpädiatrisches Zentrum, SPZ), Berlin, Germany
| | - Noor Ullah
- Institute of Biomedical and Genetic Engineering (IBGE), Islamabad, Pakistan
- Khyber Medical University Institute of Paramedical Sciences (KMU IPMS), Peshawar, Pakistan
| | - Shyamala Mani
- Charité–Universitätsmedizin Berlin, Institute of Cell Biology and Neurobiology, Berlin, Germany
- Charité–Universitätsmedizin Berlin, Department of Pediatric Neurology, Berlin, Germany
- Charité–Universitätsmedizin Berlin, Center for Chronically Sick Children (Sozialpädiatrisches Zentrum, SPZ), Berlin, Germany
| | - Elaine Guo Yan Chew
- Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
| | - Moses Tandiono
- Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
| | - Jia Nee Foo
- Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
| | - Chiea Chuen Khor
- Human Genetics, Genome Institute of Singapore, ASTAR, Singapore, Singapore
- Singapore Eye Research Institute, Singapore, Singapore
| | - Angela M. Kaindl
- Charité–Universitätsmedizin Berlin, Institute of Cell Biology and Neurobiology, Berlin, Germany
- Charité–Universitätsmedizin Berlin, Department of Pediatric Neurology, Berlin, Germany
- Charité–Universitätsmedizin Berlin, Center for Chronically Sick Children (Sozialpädiatrisches Zentrum, SPZ), Berlin, Germany
| | - Saima Siddiqi
- Institute of Biomedical and Genetic Engineering (IBGE), Islamabad, Pakistan
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8
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Leung SWS, Shi Y. The glycolytic process in endothelial cells and its implications. Acta Pharmacol Sin 2022; 43:251-259. [PMID: 33850277 PMCID: PMC8791959 DOI: 10.1038/s41401-021-00647-y] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 02/22/2021] [Indexed: 02/06/2023] Open
Abstract
Endothelial cells play an obligatory role in regulating local vascular tone and maintaining homeostasis in vascular biology. Cell metabolism, converting food to energy in organisms, is the primary self-sustaining mechanism for cell proliferation and reproduction, structure maintenance, and fight-or-flight responses to stimuli. Four major metabolic processes take place in the energy-producing process, including glycolysis, oxidative phosphorylation, glutamine metabolism, and fatty acid oxidation. Among them, glycolysis is the primary energy-producing mechanism in endothelial cells. The present review focused on glycolysis in endothelial cells under both physiological and pathological conditions. Since the switches among metabolic processes precede the functional changes and disease developments, some prophylactic and/or therapeutic strategies concerning the role of glycolysis in cardiovascular disease are discussed.
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Affiliation(s)
- Susan, Wai Sum Leung
- grid.194645.b0000000121742757Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Yi Shi
- grid.8547.e0000 0001 0125 2443Institute of Clinical Science, Zhongshan Hospital, Fudan University, Shanghai, 200032 China ,grid.8547.e0000 0001 0125 2443Key Laboratory of Organ Transplantation, Zhongshan Hospital, Fudan University, Shanghai, 200032 China
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Nguyen YTK, Ha HTT, Nguyen TH, Nguyen LN. The role of SLC transporters for brain health and disease. Cell Mol Life Sci 2021; 79:20. [PMID: 34971415 PMCID: PMC11071821 DOI: 10.1007/s00018-021-04074-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 09/05/2021] [Accepted: 10/21/2021] [Indexed: 12/19/2022]
Abstract
The brain exchanges nutrients and small molecules with blood via the blood-brain barrier (BBB). Approximately 20% energy intake for the body is consumed by the brain. Glucose is known for its critical roles for energy production and provides substrates for biogenesis in neurons. The brain takes up glucose via glucose transporters GLUT1 and 3, which are expressed in several neural cell types. The brain is also equipped with various transport systems for acquiring amino acids, lactate, ketone bodies, lipids, and cofactors for neuronal functions. Unraveling the mechanisms by which the brain takes up and metabolizes these nutrients will be key in understanding the nutritional requirements in the brain. This could also offer opportunities for therapeutic interventions in several neurological disorders. For instance, emerging evidence suggests a critical role of lactate as an alternative energy source for neurons. Neuronal cells express monocarboxylic transporters to acquire lactate. As such, treatment of GLUT1-deficient patients with ketogenic diets to provide the brain with alternative sources of energy has been shown to improve the health of the patients. Many transporters are present in the brain, but only a small number has been characterized. In this review, we will discuss about the roles of solute carrier (SLC) transporters at the blood brain barrier (BBB) and neural cells, in transport of nutrients and metabolites in the brain.
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Affiliation(s)
- Yen T K Nguyen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117596, Singapore
| | - Hoa T T Ha
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117596, Singapore
| | - Tra H Nguyen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117596, Singapore
| | - Long N Nguyen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117596, Singapore.
- SLING/Immunology Program, Life Sciences Institute, National University of Singapore, Singapore, 117456, Singapore.
- Immunology Translational and Cardiovascular Disease Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117545, Singapore.
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