1
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Frain KM, Dedic E, Nel L, Bohush A, Olesen E, Thaysen K, Wüstner D, Stokes DL, Pedersen BP. Conformational changes in the Niemann-Pick type C1 protein NCR1 drive sterol translocation. Proc Natl Acad Sci U S A 2024; 121:e2315575121. [PMID: 38568972 PMCID: PMC11009665 DOI: 10.1073/pnas.2315575121] [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: 09/08/2023] [Accepted: 02/22/2024] [Indexed: 04/05/2024] Open
Abstract
The membrane protein Niemann-Pick type C1 (NPC1, named NCR1 in yeast) is central to sterol homeostasis in eukaryotes. Saccharomyces cerevisiae NCR1 is localized to the vacuolar membrane, where it is suggested to carry sterols across the protective glycocalyx and deposit them into the vacuolar membrane. However, documentation of a vacuolar glycocalyx in fungi is lacking, and the mechanism for sterol translocation has remained unclear. Here, we provide evidence supporting the presence of a glycocalyx in isolated S. cerevisiae vacuoles and report four cryo-EM structures of NCR1 in two distinct conformations, named tense and relaxed. These two conformations illustrate the movement of sterols through a tunnel formed by the luminal domains, thus bypassing the barrier presented by the glycocalyx. Based on these structures and on comparison with other members of the Resistance-Nodulation-Division (RND) superfamily, we propose a transport model that links changes in the luminal domains with a cycle of protonation and deprotonation within the transmembrane region of the protein. Our model suggests that NPC proteins work by a generalized RND mechanism where the proton motive force drives conformational changes in the transmembrane domains that are allosterically coupled to luminal/extracellular domains to promote sterol transport.
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Affiliation(s)
- Kelly M. Frain
- Department of Molecular Biology and Genetics, Aarhus University, AarhusC 8000, Denmark
| | - Emil Dedic
- Department of Molecular Biology and Genetics, Aarhus University, AarhusC 8000, Denmark
| | - Lynette Nel
- Department of Molecular Biology and Genetics, Aarhus University, AarhusC 8000, Denmark
| | - Anastasiia Bohush
- Department of Molecular Biology and Genetics, Aarhus University, AarhusC 8000, Denmark
- Department of Molecular Biology and Genetics, Aarhus Institute of Advanced Studies, Aarhus University, AarhusC 8000, Denmark
| | - Esben Olesen
- Department of Molecular Biology and Genetics, Aarhus University, AarhusC 8000, Denmark
| | - Katja Thaysen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, OdenseM 5230, Denmark
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, OdenseM 5230, Denmark
| | - David L. Stokes
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY10016
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2
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Valdivia A, Luque FJ, Llabrés S. Binding of Cholesterol to the N-Terminal Domain of the NPC1L1 Transporter: Analysis of the Epimerization-Related Binding Selectivity and Loop Mutations. J Chem Inf Model 2024; 64:189-204. [PMID: 38152929 PMCID: PMC10777396 DOI: 10.1021/acs.jcim.3c01319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 12/29/2023]
Abstract
Cholesterol is a fat-like substance with a pivotal physiological relevance in humans, and its homeostasis is tightly regulated by various cellular processes, including the import in the small intestine and the reabsorption in the biliary ducts by the Niemann-Pick C1 Like 1 (NPC1L1) importer. NPC1L1 can mediate the absorption of a variety of sterols but strikingly exhibits a large sensitivity to cholesterol epimerization. This study examines the molecular basis of the epimerization-related selective binding of cholesterol by combining extended unbiased molecular dynamics simulations of the apo and holo species of the N-terminal domain of wild-type NPC1L1, in conjunction with relative binding free energy, umbrella sampling, and well-tempered metadynamics calculations. The analysis of the results discloses the existence of two distinct binding modes for cholesterol and epi-cholesterol. The former binds deeper in the cavity, forming key hydrogen-bond interactions with Q95, S56, and a water molecule. In contrast, epi-cholesterol is shifted ca. 3 Å to the mouth of the cavity and the transition to the Q95 site is prevented by an energetic barrier of 4.1 kcal·mol-1. Thus, the configuration of the hydroxyl group of cholesterol, together with the presence of a structural water molecule, is a key feature for effective absorption. Finally, whereas these findings may seemingly be challenged by single-point mutations that impair cholesterol transport but have a mild impact on the binding of cholesterol to the Q95 binding site, our results reveal that they have a drastic influence on the conformational landscape of the α8/β7 loop in the apo species compared to the wild-type protein. Overall, the results give support to the functional role played by the α8/β7 loop in regulating the access of ligands to NPC1L1, and hence to interpreting the impact of these mutations on diseases related to disruption of sterol absorption, paving the way to understanding certain physiological dysfunctions.
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Affiliation(s)
- Aitor Valdivia
- Departament
de Nutrició, Ciències de l′Alimentació
i Gastronomia, Facultat de Farmàcia
i Ciències de l′Alimentació—Campus Torribera,
Universitat de Barcelona, Prat de la Riba 171, 08921 Santa Coloma de Gramenet, Spain
- Institut
de Biomedicina (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
| | - F. Javier Luque
- Departament
de Nutrició, Ciències de l′Alimentació
i Gastronomia, Facultat de Farmàcia
i Ciències de l′Alimentació—Campus Torribera,
Universitat de Barcelona, Prat de la Riba 171, 08921 Santa Coloma de Gramenet, Spain
- Institut
de Biomedicina (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
- Institut
de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08921 Barcelona, Spain
| | - Salomé Llabrés
- Departament
de Nutrició, Ciències de l′Alimentació
i Gastronomia, Facultat de Farmàcia
i Ciències de l′Alimentació—Campus Torribera,
Universitat de Barcelona, Prat de la Riba 171, 08921 Santa Coloma de Gramenet, Spain
- Institut
de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08921 Barcelona, Spain
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3
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Goul C, Peruzzo R, Zoncu R. The molecular basis of nutrient sensing and signalling by mTORC1 in metabolism regulation and disease. Nat Rev Mol Cell Biol 2023; 24:857-875. [PMID: 37612414 DOI: 10.1038/s41580-023-00641-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2023] [Indexed: 08/25/2023]
Abstract
The Ser/Thr kinase mechanistic target of rapamycin (mTOR) is a central regulator of cellular metabolism. As part of mTOR complex 1 (mTORC1), mTOR integrates signals such as the levels of nutrients, growth factors, energy sources and oxygen, and triggers responses that either boost anabolism or suppress catabolism. mTORC1 signalling has wide-ranging consequences for the growth and homeostasis of key tissues and organs, and its dysregulated activity promotes cancer, type 2 diabetes, neurodegeneration and other age-related disorders. How mTORC1 integrates numerous upstream cues and translates them into specific downstream responses is an outstanding question with major implications for our understanding of physiology and disease mechanisms. In this Review, we discuss recent structural and functional insights into the molecular architecture of mTORC1 and its lysosomal partners, which have greatly increased our mechanistic understanding of nutrient-dependent mTORC1 regulation. We also discuss the emerging involvement of aberrant nutrient-mTORC1 signalling in multiple diseases.
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Affiliation(s)
- Claire Goul
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Roberta Peruzzo
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
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4
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Altuzar J, Notbohm J, Stein F, Haberkant P, Hempelmann P, Heybrock S, Worsch J, Saftig P, Höglinger D. Lysosome-targeted multifunctional lipid probes reveal the sterol transporter NPC1 as a sphingosine interactor. Proc Natl Acad Sci U S A 2023; 120:e2213886120. [PMID: 36893262 PMCID: PMC10089177 DOI: 10.1073/pnas.2213886120] [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: 08/12/2022] [Accepted: 01/31/2023] [Indexed: 03/11/2023] Open
Abstract
Lysosomes are catabolic organelles involved in macromolecular digestion, and their dysfunction is associated with pathologies ranging from lysosomal storage disorders to common neurodegenerative diseases, many of which have lipid accumulation phenotypes. The mechanism of lipid efflux from lysosomes is well understood for cholesterol, while the export of other lipids, particularly sphingosine, is less well studied. To overcome this knowledge gap, we have developed functionalized sphingosine and cholesterol probes that allow us to follow their metabolism, protein interactions, and their subcellular localization. These probes feature a modified cage group for lysosomal targeting and controlled release of the active lipids with high temporal precision. An additional photocrosslinkable group allowed for the discovery of lysosomal interactors for both sphingosine and cholesterol. In this way, we found that two lysosomal cholesterol transporters, NPC1 and to a lesser extent LIMP-2/SCARB2, bind to sphingosine and showed that their absence leads to lysosomal sphingosine accumulation which hints at a sphingosine transport role of both proteins. Furthermore, artificial elevation of lysosomal sphingosine levels impaired cholesterol efflux, consistent with sphingosine and cholesterol sharing a common export mechanism.
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Affiliation(s)
- Janathan Altuzar
- Heidelberg University Biochemistry Center, Ruprecht-Karls-Universität Heidelberg, 69120Heidelberg, Germany
| | - Judith Notbohm
- Heidelberg University Biochemistry Center, Ruprecht-Karls-Universität Heidelberg, 69120Heidelberg, Germany
| | - Frank Stein
- European Molecular Biology Laboratory, 69117Heidelberg, Germany
| | - Per Haberkant
- European Molecular Biology Laboratory, 69117Heidelberg, Germany
| | - Pia Hempelmann
- Heidelberg University Biochemistry Center, Ruprecht-Karls-Universität Heidelberg, 69120Heidelberg, Germany
| | - Saskia Heybrock
- Institute of Biochemistry, Christian-Albrechts-Universität Kiel, 24118Kiel, Germany
| | - Jutta Worsch
- Heidelberg University Biochemistry Center, Ruprecht-Karls-Universität Heidelberg, 69120Heidelberg, Germany
| | - Paul Saftig
- Institute of Biochemistry, Christian-Albrechts-Universität Kiel, 24118Kiel, Germany
| | - Doris Höglinger
- Heidelberg University Biochemistry Center, Ruprecht-Karls-Universität Heidelberg, 69120Heidelberg, Germany
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5
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The Cerebellum in Niemann-Pick C1 Disease: Mouse Versus Man. CEREBELLUM (LONDON, ENGLAND) 2023; 22:102-119. [PMID: 35040097 DOI: 10.1007/s12311-021-01347-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/17/2021] [Indexed: 02/01/2023]
Abstract
Selective neuronal vulnerability is common to most degenerative disorders, including Niemann-Pick C (NPC), a rare genetic disease with altered intracellular trafficking of cholesterol. Purkinje cell dysfunction and loss are responsible for cerebellar ataxia, which is among the prevailing neurological signs of the NPC disease. In this review, we focus on some questions that are still unresolved. First, we frame the cerebellar vulnerability in the context of the extended postnatal time length by which the development of this structure is completed in mammals. In line with this thought, the much later development of cerebellar symptoms in humans is due to the later development and/or maturation of the cerebellum. Hence, the occurrence of developmental events under a protracted condition of defective intracellular cholesterol mobilization hits the functional maturation of the various cell types generating the ground of increased vulnerability. This is particularly consistent with the high cholesterol demand required for cell proliferation, migration, differentiation, and synapse formation/remodeling. Other major questions we address are why the progression of Purkinje cells loss is always from the anterior to the posterior lobes and why cerebellar defects persist in the mouse model even when genetic manipulations can lead to nearly normal survival.
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6
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Bruno F, Camuso S, Capuozzo E, Canterini S. The Antifungal Antibiotic Filipin as a Diagnostic Tool of Cholesterol Alterations in Lysosomal Storage Diseases and Neurodegenerative Disorders. Antibiotics (Basel) 2023; 12:antibiotics12010122. [PMID: 36671323 PMCID: PMC9855188 DOI: 10.3390/antibiotics12010122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/05/2023] [Accepted: 01/05/2023] [Indexed: 01/10/2023] Open
Abstract
Cholesterol is the most considerable member of a family of polycyclic compounds understood as sterols, and represents an amphipathic molecule, such as phospholipids, with the polar hydroxyl group located in position 3 and the rest of the molecule is completely hydrophobic. In cells, it is usually present as free, unesterified cholesterol, or as esterified cholesterol, in which the hydroxyl group binds to a carboxylic acid and thus generates an apolar molecule. Filipin is a naturally fluorescent antibiotic that exerts a primary antifungal effect with low antibacterial activity, interfering with the sterol stabilization of the phospholipid layers and favoring membrane leakage. This polyene macrolide antibiotic does not bind to esterified sterols, but only to non-esterified cholesterol, and it is commonly used as a marker to label and quantify free cholesterol in cells and tissues. Several lines of evidence have indicated that filipin staining could be a good diagnostic tool for the cholesterol alterations present in neurodegenerative (e.g., Alzheimer's Disease and Huntington Disease) and lysosomal storage diseases (e.g., Niemann Pick type C Disease and GM1 gangliosidosis). Here, we have discussed the uses and applications of this fluorescent molecule in lipid storage diseases and neurodegenerative disorders, exploring not only the diagnostic strength of filipin staining, but also its limitations, which over the years have led to the development of new diagnostic tools to combine with filipin approach.
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Affiliation(s)
- Francesco Bruno
- Regional Neurogenetic Centre (CRN), Department of Primary Care, ASP Catanzaro, 88046 Lamezia Terme, Italy
- Association for Neurogenetic Research (ARN), 88046 Lamezia Terme, Italy
| | - Serena Camuso
- Division of Neuroscience, Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy
| | - Elisabetta Capuozzo
- Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy
- Correspondence: (E.C.); (S.C.)
| | - Sonia Canterini
- Division of Neuroscience, Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy
- Correspondence: (E.C.); (S.C.)
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7
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Li JK, Rao YQ, Koh SK, Zhao P, Zhou L, Li J. Proteomic analysis of s-acylated proteins in human retinal pigment epithelial cells and the role of palmitoylation of Niemann-Pick type C1 protein in cholesterol transport. Front Aging Neurosci 2022; 14:965943. [PMID: 36262888 PMCID: PMC9576141 DOI: 10.3389/fnagi.2022.965943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 08/26/2022] [Indexed: 11/13/2022] Open
Abstract
Palmitoylation is a dynamic process that regulates the activity of the modified proteins. Retinal pigment epithelial (RPE) cells play pivotal roles in the visual cycle and maintaining healthy photoreceptor cells. Dysfunctional RPE cells are often associated with degenerative retinal diseases. The aim of the study was to identify potentially palmitoylated proteins in human RPE cells. By using the detergent-resistant membrane, we found 312 potentially palmitoylated peptides which corresponded to 192 proteins in RPE cells, including 55 new candidate proteins which were not reported before. Gene enrichment analysis highlighted significant enrichment of palmitoylated proteins in cell-matrix adhesion, cell-cell recognition, protein cellular localization, and translation, among others. We further studied the effect of 3 potential palmitoylation sites (Cys 799, 900, and 816) of Niemann-Pick type C1 protein (NPC1) on cholesterol accumulation. We found that mutation of any single Cys alone had no significant effect on intracellular cholesterol accumulation while simultaneous mutation of Cys799 and 800 caused significant cholesterol accumulation in the late endosome. No further cholesterol accumulation was observed by adding another mutation at Cys 816. However, the mutation did not alter the cellular localization of the protein. Conclusion: PRE cells have an abundant number of palmitoylated proteins which are involved in cellular processes critical to visual function. The palmitoylation at Cys799 and 800 was needed for cholesterol export, but not the intracellular localization of NPC1.
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Affiliation(s)
- Jia Kai Li
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yu Qing Rao
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Siew Kwan Koh
- Singapore Eye Research Institute, Singapore, Singapore
| | - Peiquan Zhao
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lei Zhou
- Singapore Eye Research Institute, Singapore, Singapore
- Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Ophthalmology and Visual Sciences Academic Clinical Research Program, Duke-NUS Medical School, National University of Singapore, Singapore, Singapore
- *Correspondence: Lei Zhou,
| | - Jing Li
- Department of Ophthalmology, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Jing Li,
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8
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Shin HR, Citron YR, Wang L, Tribouillard L, Goul CS, Stipp R, Sugasawa Y, Jain A, Samson N, Lim CY, Davis OB, Castaneda-Carpio D, Qian M, Nomura DK, Perera RM, Park E, Covey DF, Laplante M, Evers AS, Zoncu R. Lysosomal GPCR-like protein LYCHOS signals cholesterol sufficiency to mTORC1. Science 2022; 377:1290-1298. [PMID: 36007018 PMCID: PMC10023259 DOI: 10.1126/science.abg6621] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Lysosomes coordinate cellular metabolism and growth upon sensing of essential nutrients, including cholesterol. Through bioinformatic analysis of lysosomal proteomes, we identified lysosomal cholesterol signaling (LYCHOS, previously annotated as G protein-coupled receptor 155), a multidomain transmembrane protein that enables cholesterol-dependent activation of the master growth regulator, the protein kinase mechanistic target of rapamycin complex 1 (mTORC1). Cholesterol bound to the amino-terminal permease-like region of LYCHOS, and mutating this site impaired mTORC1 activation. At high cholesterol concentrations, LYCHOS bound to the GATOR1 complex, a guanosine triphosphatase (GTPase)-activating protein for the Rag GTPases, through a conserved cytoplasm-facing loop. By sequestering GATOR1, LYCHOS promotes cholesterol- and Rag-dependent recruitment of mTORC1 to lysosomes. Thus, LYCHOS functions in a lysosomal pathway for cholesterol sensing and couples cholesterol concentrations to mTORC1-dependent anabolic signaling.
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Affiliation(s)
- Hijai R. Shin
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Initiative at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Y. Rose Citron
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Initiative at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Lei Wang
- Department of Anesthesiology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Laura Tribouillard
- Centre de recherche sur le cancer de l’Université Laval, Université Laval, Québec, QC, G1R 3S3, Canada
| | - Claire S. Goul
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Initiative at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Robin Stipp
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Initiative at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Yusuke Sugasawa
- Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo 113-8421, Japan
| | - Aakriti Jain
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Initiative at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Nolwenn Samson
- Centre de recherche sur le cancer de l’Université Laval, Université Laval, Québec, QC, G1R 3S3, Canada
| | - Chun-Yan Lim
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Initiative at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Oliver B. Davis
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Initiative at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - David Castaneda-Carpio
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Initiative at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Mingxing Qian
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Daniel K. Nomura
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Department of Nutritional Sciences and Toxicology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Rushika M. Perera
- Department of Anatomy, University of California San Francisco, San Francisco, CA 94143, USA
| | - Eunyong Park
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Douglas F. Covey
- Department of Developmental Biology and Biochemistry, Washington University School of Medicine, St Louis, MO 63110, USA
- The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Mathieu Laplante
- Centre de recherche sur le cancer de l’Université Laval, Université Laval, Québec, QC, G1R 3S3, Canada
| | - Alex S. Evers
- Department of Anesthesiology, Washington University School of Medicine, St Louis, MO 63110, USA
- Department of Developmental Biology and Biochemistry, Washington University School of Medicine, St Louis, MO 63110, USA
- The Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
- Innovative Genomics Initiative at the University of California, Berkeley, Berkeley, CA 94720, USA
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9
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Lu A. Endolysosomal cholesterol export: More than just NPC1. Bioessays 2022; 44:e2200111. [PMID: 35934896 DOI: 10.1002/bies.202200111] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/22/2022] [Accepted: 07/26/2022] [Indexed: 11/07/2022]
Abstract
NPC1 plays a central role in cholesterol egress from endolysosomes, a critical step for maintaining intracellular cholesterol homeostasis. Despite recent advances in the field, the full repertoire of molecules and pathways involved in this process remains unknown. Emerging evidence suggests the existence of NPC1-independent, alternative routes. These may involve vesicular and non-vesicular mechanisms, as well as release of extracellular vesicles. Understanding the underlying molecular mechanisms that bypass NPC1 function could have important implications for the development of therapies for lysosomal storage disorders. Here we discuss how cholesterol may be exported from lysosomes in which NPC1 function is impaired.
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Affiliation(s)
- Albert Lu
- Departament de Biomedicina, Unitat de Biologia Cellular, Facultat de Medicina i Ciències de la Salut, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Universitat de Barcelona, Barcelona, Spain
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10
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Yoon HJ, Jeong J, Kim G, Lee HH, Jang S. The point mutation of the cholesterol trafficking membrane protein NPC1 may affect its proper function in more than a single step: Molecular dynamics simulation study. Comput Biol Chem 2022; 99:107725. [PMID: 35850050 DOI: 10.1016/j.compbiolchem.2022.107725] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 06/29/2022] [Accepted: 07/04/2022] [Indexed: 11/16/2022]
Abstract
The Niemann-Pick type C1 (NPC1) protein is one of the key players of cholesterol trafficking from the lysosome and its function is closely coupled with the Niemann-Pick type C2 (NPC2) protein. The dysfunction of one of these proteins can cause problems in the overall cholesterol homeostasis and leads to a disease, which is called the Niemann-Pick type C (NPC) disease. The parts of the cholesterol transport mechanism by NPC1 have begun to recently emerge, especially after the full-length NPC1 structure was determined from a cryo-EM study. However, many details about the overall cholesterol trafficking process by NPC1 still remain to be elucidated. Notably, the NPC1 could act as one of the target proteins for the control of infectious diseases due to its role as the virus entry point into the cells as well as for cancer treatment due to the inhibitory effect of tumor growth. A mutation of NPC1 can leads to dysfunctions and understanding this process can provide valuable insights into the mechanisms of the corresponding protein and the therapeutic strategies against the disease that are caused by the mutation. It has been found that patients with the point mutation R518W (or R518Q) on the NPC1 show the accumulation of lipids within the lysosomal lumen. In this paper, we report how the corresponding mutation can affect the cholesterol transport process by NPC1 in the different stages by the molecular dynamics simulations. The simulation results show that the point mutation intervenes at least at two different steps during the cholesterol transport by NPC1 and NPC2 in combination, which includes the association step of NPC2 with the NPC1, the cholesterol transfer step from NPC2 to NPC1-NTD while the cholesterol passage within the NPC1 via a channel is relatively unaffected by R518W mutation. The detailed analysis of the resulting simulation trajectories reveals the important structural features that are essential for the proper functioning of the NPC1 for the cholesterol transport, and it shows how the overall structure, which thereby includes the function, can be affected by a single mutation.
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Affiliation(s)
- Hye-Jin Yoon
- Department of Chemistry, Seoul National University, Seoul, the Republic of Korea
| | - Jian Jeong
- Department of Chemistry, Sejong University, Seoul, the Republic of Korea
| | - Guun Kim
- Department of Physics, Sejong University, Seoul, the Republic of Korea
| | - Hyung Ho Lee
- Department of Chemistry, Seoul National University, Seoul, the Republic of Korea.
| | - Soonmin Jang
- Department of Chemistry, Sejong University, Seoul, the Republic of Korea.
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11
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Lu A, Hsieh F, Sharma BR, Vaughn SR, Enrich C, Pfeffer SR. CRISPR screens for lipid regulators reveal a role for ER-bound SNX13 in lysosomal cholesterol export. J Cell Biol 2022; 221:212937. [PMID: 34936700 PMCID: PMC8704955 DOI: 10.1083/jcb.202105060] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 11/02/2021] [Accepted: 11/29/2021] [Indexed: 11/22/2022] Open
Abstract
We report here two genome-wide CRISPR screens performed to identify genes that, when knocked out, alter levels of lysosomal cholesterol or bis(monoacylglycero)phosphate. In addition, these screens were also performed under conditions of NPC1 inhibition to identify modifiers of NPC1 function in lysosomal cholesterol export. The screens confirm tight coregulation of cholesterol and bis(monoacylglycero)phosphate in cells and reveal an unexpected role for the ER-localized SNX13 protein as a negative regulator of lysosomal cholesterol export and contributor to ER–lysosome membrane contact sites. In the absence of NPC1 function, SNX13 knockdown redistributes lysosomal cholesterol and is accompanied by triacylglycerol-rich lipid droplet accumulation and increased lysosomal bis(monoacylglycero)phosphate. These experiments provide unexpected insight into the regulation of lysosomal lipids and modification of these processes by novel gene products.
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Affiliation(s)
- Albert Lu
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA.,Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Universitat de Barcelona, Barcelona, Spain
| | | | - Bikal R Sharma
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA
| | - Sydney R Vaughn
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA
| | - Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Universitat de Barcelona, Barcelona, Spain
| | - Suzanne R Pfeffer
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA
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12
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Wu X, Yan R, Cao P, Qian H, Yan N. Structural advances in sterol-sensing domain-containing proteins. Trends Biochem Sci 2022; 47:289-300. [PMID: 35012873 DOI: 10.1016/j.tibs.2021.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 12/26/2022]
Abstract
The sterol-sensing domain (SSD) is present in several membrane proteins that function in cholesterol metabolism, transport, and signaling. Recent progress in structural studies of SSD-containing proteins, such as sterol regulatory element-binding protein (SREBP)-cleavage activating protein (Scap), Patched, Niemann-Pick disease type C1 (NPC1), and related proteins, reveals a conserved core that is essential for their sterol-dependent functions. This domain, by its name, 'senses' the presence of sterol substrates through interactions and may modulate protein behaviors with changing sterol levels. We summarize recent advances in structural and mechanistic investigations of these proteins and propose to divide them to two classes: M for 'moderator' proteins that regulate sterol metabolism in response to membrane sterol levels, and T for 'transporter' proteins that harbor inner tunnels for cargo trafficking across cellular membranes.
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Affiliation(s)
- Xuelan Wu
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Renhong Yan
- Westlake Laboratory of Life Sciences and Biomedicine, Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China; Institute of Biology, Westlake Institute for Advanced Study, 18 Shilongshan Road, Hangzhou 310024, Zhejiang Province, China
| | - Pingping Cao
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Hongwu Qian
- Ministry of Education (MOE) Key Laboratory of Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, and Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.
| | - Nieng Yan
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
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13
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Winkler MBL, Nel L, Frain KM, Dedic E, Olesen E, Pedersen BP. Sterol uptake by the NPC system in eukaryotes: a Saccharomyces cerevisiae perspective. FEBS Lett 2022; 596:160-179. [PMID: 34897668 DOI: 10.1002/1873-3468.14253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/03/2021] [Accepted: 12/03/2021] [Indexed: 12/11/2022]
Abstract
Sterols are an essential component of membranes in all eukaryotic cells and the precursor of multiple indispensable cellular metabolites. After endocytotic uptake, sterols are integrated into the lysosomal membrane by the Niemann-Pick type C (NPC) system before redistribution to other membranes. The process is driven by two proteins that, together, compose the NPC system: the lysosomal sterol shuttle protein NPC2 and the membrane protein NPC1 (named NCR1 in fungi), which integrates sterols into the lysosomal membrane. The Saccharomyces cerevisiae NPC system provides a compelling model to study the molecular mechanism of sterol integration into membranes and sterol homeostasis. This review summarizes recent advances in the field, and by interpreting available structural data, we propose a unifying conceptual model for sterol loading, transfer and transport by NPC proteins.
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Affiliation(s)
- Mikael B L Winkler
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
| | - Lynette Nel
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
| | - Kelly M Frain
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
| | - Emil Dedic
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
| | - Esben Olesen
- Department of Molecular Biology and Genetics, Aarhus University, Denmark
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14
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Barrantes FJ. Fluorescence sensors for imaging membrane lipid domains and cholesterol. CURRENT TOPICS IN MEMBRANES 2021; 88:257-314. [PMID: 34862029 DOI: 10.1016/bs.ctm.2021.09.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Lipid membrane domains are supramolecular lateral heterogeneities of biological membranes. Of nanoscopic dimensions, they constitute specialized hubs used by the cell as transient signaling platforms for a great variety of biologically important mechanisms. Their property to form and dissolve in the bulk lipid bilayer endow them with the ability to engage in highly dynamic processes, and temporarily recruit subpopulations of membrane proteins in reduced nanometric compartments that can coalesce to form larger mesoscale assemblies. Cholesterol is an essential component of these lipid domains; its unique molecular structure is suitable for interacting intricately with crevices and cavities of transmembrane protein surfaces through its rough β face while "talking" to fatty acid acyl chains of glycerophospholipids and sphingolipids via its smooth α face. Progress in the field of membrane domains has been closely associated with innovative improvements in fluorescence microscopy and new fluorescence sensors. These advances enabled the exploration of the biophysical properties of lipids and their supramolecular platforms. Here I review the rationale behind the use of biosensors over the last few decades and their contributions towards elucidation of the in-plane and transbilayer topography of cholesterol-enriched lipid domains and their molecular constituents. The challenges introduced by super-resolution optical microscopy are discussed, as well as possible scenarios for future developments in the field, including virtual ("no staining") staining.
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Affiliation(s)
- Francisco J Barrantes
- Biomedical Research Institute (BIOMED), Catholic University of Argentina (UCA)-National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina.
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15
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Long T, Liu Y, Qin Y, DeBose-Boyd RA, Li X. Structures of dimeric human NPC1L1 provide insight into mechanisms for cholesterol absorption. SCIENCE ADVANCES 2021; 7:7/34/eabh3997. [PMID: 34407950 PMCID: PMC8373123 DOI: 10.1126/sciadv.abh3997] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 06/28/2021] [Indexed: 05/05/2023]
Abstract
Polytopic Niemann-Pick C1-like 1 (NPC1L1) plays a major role in intestinal absorption of biliary cholesterol, vitamin E (VE), and vitamin K (VK). The drug ezetimibe inhibits NPC1L1-mediated absorption of cholesterol, lowering of circulating levels of low-density lipoprotein cholesterol. Here, we report cryo-electron microscopy structures of human NPC1L1 (hNPC1L1) bound to either cholesterol or a lipid resembling VE. These findings, together with functional assays, reveal that the same intramolecular channel in hNPC1L1 mediates transport of VE and cholesterol. hNPC1L1 exists primarily as a homodimer; dimerization is mediated by aromatic residues within a region of transmembrane helix 2 that exhibits a horizonal orientation in the membrane. Mutation of tryptophan-347 lies in this region disrupts dimerization and the resultant monomeric NPC1L1 exhibits reduced efficiency of cholesterol uptake. These findings identify the oligomeric state of hNPC1L1 as a target for therapies that inhibit uptake of dietary cholesterol and reduce the incidence of cardiovascular disease.
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Affiliation(s)
- Tao Long
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yang Liu
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yu Qin
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Russell A DeBose-Boyd
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Xiaochun Li
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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16
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Hu M, Yang F, Huang Y, You X, Liu D, Sun S, Sui SF. Structural insights into the mechanism of human NPC1L1-mediated cholesterol uptake. SCIENCE ADVANCES 2021; 7:7/29/eabg3188. [PMID: 34272236 PMCID: PMC8284890 DOI: 10.1126/sciadv.abg3188] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 06/03/2021] [Indexed: 05/28/2023]
Abstract
Niemann-Pick C1-like 1 (NPC1L1) protein plays a central role in the intestinal cholesterol absorption and is the target of a drug, ezetimibe, which inhibits NPC1L1 to reduce cholesterol absorption. Here, we present cryo-electron microscopy structures of human NPC1L1 in apo state, cholesterol-enriched state, and ezetimibe-bound state to reveal molecular details of NPC1L1-mediated cholesterol uptake and ezetimibe inhibition. Comparison of these structures reveals that the sterol-sensing domain (SSD) could respond to the cholesterol level alteration by binding different number of cholesterol molecules. Upon increasing cholesterol level, SSD binds more cholesterol molecules, which, in turn, triggers the formation of a stable structural cluster in SSD, while binding of ezetimibe causes the deformation of the SSD and destroys the structural cluster, leading to the inhibition of NPC1L1 function. These results provide insights into mechanisms of NPC1L1 function and ezetimibe action and are of great significance for the development of new cholesterol absorption inhibitors.
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Affiliation(s)
- Miaoqing Hu
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China
- Department of Biology, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
| | - Fan Yang
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yawen Huang
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xin You
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Desheng Liu
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shan Sun
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Sen-Fang Sui
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China.
- Department of Biology, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
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17
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Cruz DL, Pipalia N, Mao S, Gadi D, Liu G, Grigalunas M, O'Neill M, Quinn TR, Kipper A, Ekebergh A, Dimmling A, Gartner C, Melancon BJ, Wagner FF, Holson E, Helquist P, Wiest O, Maxfield FR. Inhibition of Histone Deacetylases 1, 2, and 3 Enhances Clearance of Cholesterol Accumulation in Niemann-Pick C1 Fibroblasts. ACS Pharmacol Transl Sci 2021; 4:1136-1148. [PMID: 34151204 PMCID: PMC8204796 DOI: 10.1021/acsptsci.1c00033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Indexed: 11/29/2022]
Abstract
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Niemann-Pick disease type C1 (NPC1) is a rare genetic cholesterol storage disorder
caused by mutations in the NPC1 gene. Mutations in this transmembrane
late endosome protein lead to loss of normal cholesterol efflux from late endosomes and
lysosomes. It has been shown that broad spectrum histone deacetylase inhibitors
(HDACi's) such as Vorinostat correct the cholesterol accumulation phenotype in the
majority of NPC1 mutants tested in cultured cells. In order to determine the optimal
specificity for HDACi correction of the mutant NPC1s, we screened 76 HDACi's of varying
specificity. We tested the ability of these HDACi's to correct the excess accumulation
of cholesterol in patient fibroblast cells that homozygously express
NPC1I1061T, the most common mutation. We
determined that inhibition of HDACs 1, 2, and 3 is important for correcting the defect,
and combined inhibition of all three is needed to achieve the greatest effect,
suggesting a need for multiple effects of the HDACi treatments. Identifying the specific
HDACs involved in the process of regulating cholesterol trafficking in NPC1 will help to
focus the search for more specific druggable targets.
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Affiliation(s)
- Dana L Cruz
- Department of Biochemistry, Weill Cornell Medical College, New York, New York 10065, United States
| | - Nina Pipalia
- Department of Biochemistry, Weill Cornell Medical College, New York, New York 10065, United States
| | - Shu Mao
- Department of Biochemistry, Weill Cornell Medical College, New York, New York 10065, United States
| | - Deepti Gadi
- Department of Biochemistry, Weill Cornell Medical College, New York, New York 10065, United States
| | - Gang Liu
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Michael Grigalunas
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Matthew O'Neill
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Taylor R Quinn
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Andi Kipper
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Andreas Ekebergh
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Alexander Dimmling
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Carlos Gartner
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Bruce J Melancon
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Florence F Wagner
- Eli and Edythe L. Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, United States
| | - Edward Holson
- Eli and Edythe L. Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, United States.,KDAc Therapeutics, Cambridge, Massachusetts 02142, United States
| | - Paul Helquist
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Olaf Wiest
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.,Laboratory of Computational Chemistry and Drug Design, State Key Laboratory of Chemical Oncogenomics, Peking University, Shenzhen Graduate School, Shenzhen 518055, P.R. China
| | - Frederick R Maxfield
- Department of Biochemistry, Weill Cornell Medical College, New York, New York 10065, United States
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18
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Li YE, Wang Y, Du X, Zhang T, Mak HY, Hancock SE, McEwen H, Pandzic E, Whan RM, Aw YC, Lukmantara IE, Yuan Y, Dong X, Don A, Turner N, Qi S, Yang H. TMEM41B and VMP1 are scramblases and regulate the distribution of cholesterol and phosphatidylserine. J Cell Biol 2021; 220:212020. [PMID: 33929485 PMCID: PMC8077175 DOI: 10.1083/jcb.202103105] [Citation(s) in RCA: 88] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/10/2021] [Accepted: 04/15/2021] [Indexed: 02/08/2023] Open
Abstract
TMEM41B and VMP1 are integral membrane proteins of the endoplasmic reticulum (ER) and regulate the formation of autophagosomes, lipid droplets (LDs), and lipoproteins. Recently, TMEM41B was identified as a crucial host factor for infection by all coronaviruses and flaviviruses. The molecular function of TMEM41B and VMP1, which belong to a large evolutionarily conserved family, remains elusive. Here, we show that TMEM41B and VMP1 are phospholipid scramblases whose deficiency impairs the normal cellular distribution of cholesterol and phosphatidylserine. Their mechanism of action on LD formation is likely to be different from that of seipin. Their role in maintaining cellular phosphatidylserine and cholesterol homeostasis may partially explain their requirement for viral infection. Our results suggest that the proper sorting and distribution of cellular lipids are essential for organelle biogenesis and viral infection.
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Affiliation(s)
- Yang Emma Li
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Yichang Wang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Tizhong Zhang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Hoi Yin Mak
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Sarah E Hancock
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Holly McEwen
- Centenary Institute, The University of Sydney, Camperdown, New South Wales, Australia.,National Health and Medical Research Council Clinical Trials Center, The University of Sydney, Camperdown, New South Wales, Australia
| | - Elvis Pandzic
- Biomedical Imaging Facility, Mark Wainwright Analytical Center, New South Wales, Australia
| | - Renee M Whan
- Biomedical Imaging Facility, Mark Wainwright Analytical Center, New South Wales, Australia
| | - Yvette Celine Aw
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Ivan E Lukmantara
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Yiqiong Yuan
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Xiuju Dong
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Anthony Don
- Centenary Institute, The University of Sydney, Camperdown, New South Wales, Australia.,National Health and Medical Research Council Clinical Trials Center, The University of Sydney, Camperdown, New South Wales, Australia
| | - Nigel Turner
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Shiqian Qi
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, Chengdu, China
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
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19
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Allende ML, Zhu H, Kono M, Hoachlander-Hobby LE, Huso VL, Proia RL. Genetic defects in the sphingolipid degradation pathway and their effects on microglia in neurodegenerative disease. Cell Signal 2021; 78:109879. [PMID: 33296739 PMCID: PMC7775721 DOI: 10.1016/j.cellsig.2020.109879] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/02/2020] [Accepted: 12/03/2020] [Indexed: 12/15/2022]
Abstract
Sphingolipids, which function as plasma membrane lipids and signaling molecules, are highly enriched in neuronal and myelin membranes in the nervous system. They are degraded in lysosomes by a defined sequence of enzymatic steps. In the related group of disorders, the sphingolipidoses, mutations in the genes that encode the individual degradative enzymes cause lysosomal accumulation of sphingolipids and often result in severe neurodegenerative disease. Here we review the information indicating that microglia, which actively clear sphingolipid-rich membranes in the brain during development and homeostasis, are directly affected by these mutations and promote neurodegeneration in the sphingolipidoses. We also identify parallels between the sphingolipidoses and more common forms of neurodegeneration, which both exhibit evidence of defective sphingolipid clearance in the nervous system.
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Affiliation(s)
- Maria L Allende
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hongling Zhu
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mari Kono
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lila E Hoachlander-Hobby
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA
| | - Vienna L Huso
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA
| | - Richard L Proia
- Genetics of Development and Disease Section, Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, 9000 Rockville Pike, National Institutes of Health, Bethesda, MD 20892, USA.
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20
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Shioi R, Karaki F, Yoshioka H, Noguchi-Yachide T, Ishikawa M, Dodo K, Hashimoto Y, Sodeoka M, Ohgane K. Image-based screen capturing misfolding status of Niemann-Pick type C1 identifies potential candidates for chaperone drugs. PLoS One 2020; 15:e0243746. [PMID: 33315900 PMCID: PMC7735562 DOI: 10.1371/journal.pone.0243746] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 11/26/2020] [Indexed: 02/07/2023] Open
Abstract
Niemann-Pick disease type C is a rare, fatal neurodegenerative disorder characterized by massive intracellular accumulation of cholesterol. In most cases, loss-of-function mutations in the NPC1 gene that encodes lysosomal cholesterol transporter NPC1 are responsible for the disease, and more than half of the mutations are considered to interfere with the biogenesis or folding of the protein. We previously identified a series of oxysterol derivatives and phenanthridine-6-one derivatives as pharmacological chaperones, i.e., small molecules that can rescue folding-defective phenotypes of mutated NPC1, opening up an avenue to develop chaperone therapy for Niemann-Pick disease type C. Here, we present an improved image-based screen for NPC1 chaperones and we describe its application for drug-repurposing screening. We identified some azole antifungals, including itraconazole and posaconazole, and a kinase inhibitor, lapatinib, as probable pharmacological chaperones. A photo-crosslinking study confirmed direct binding of itraconazole to a representative folding-defective mutant protein, NPC1-I1061T. Competitive photo-crosslinking experiments suggested that oxysterol-based chaperones and itraconazole share the same or adjacent binding site(s), and the sensitivity of the crosslinking to P691S mutation in the sterol-sensing domain supports the hypothesis that their binding sites are located near this domain. Although the azoles were less effective in reducing cholesterol accumulation than the oxysterol-derived chaperones or an HDAC inhibitor, LBH-589, our findings should offer new starting points for medicinal chemistry efforts to develop better pharmacological chaperones for NPC1.
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Affiliation(s)
- Ryuta Shioi
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Fumika Karaki
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Hiromasa Yoshioka
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Tomomi Noguchi-Yachide
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Minoru Ishikawa
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai, Japan
| | - Kosuke Dodo
- Synthetic Organic Chemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Yuichi Hashimoto
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Mikiko Sodeoka
- Synthetic Organic Chemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Kenji Ohgane
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Synthetic Organic Chemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan
- * E-mail:
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21
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Dubey V, Bozorg B, Wüstner D, Khandelia H. Cholesterol binding to the sterol-sensing region of Niemann Pick C1 protein confines dynamics of its N-terminal domain. PLoS Comput Biol 2020; 16:e1007554. [PMID: 33021976 PMCID: PMC7537887 DOI: 10.1371/journal.pcbi.1007554] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 07/02/2020] [Indexed: 12/12/2022] Open
Abstract
Lysosomal accumulation of cholesterol is a hallmark of Niemann Pick type C (NPC) disease caused by mutations primarily in the lysosomal membrane protein NPC1. NPC1 contains a transmembrane sterol-sensing domain (SSD), which is supposed to regulate protein activity upon cholesterol binding, but the mechanisms underlying this process are poorly understood. Using atomistic simulations, we show that in the absence of cholesterol in the SSD, the luminal domains of NPC1 are highly dynamic, resulting in the disengagement of the NTD from the rest of the protein. The disengaged NPC1 adopts a flexed conformation that approaches the lipid bilayer, and could represent a conformational state primed to receive a sterol molecule from the soluble lysosomal cholesterol carrier NPC2. The binding of cholesterol to the SSD of NPC1 allosterically suppresses the conformational dynamics of the luminal domains resulting in an upright NTD conformation. The presence of an additional 20% cholesterol in the membrane has negligible impact on this process. The additional presence of an NTD-bound cholesterol suppresses the flexing of the NTD. We propose that cholesterol acts as an allosteric effector, and the modulation of NTD dynamics by the SSD-bound cholesterol constitutes an allosteric feedback mechanism in NPC1 that controls cholesterol abundance in the lysosomal membrane. Cholesterol is absorbed from LDL particles in esterified form, and is broken down to free cholesterol in the lysosomes of cells, from where cholesterol must be transported to other cellular compartments such as the plasma membrane. The Niemann Pick type C (NPC) diseases arise from deficient cholesterol transport and result from mutations in the cholesterol transport protein NPC1. Using computer simulations, we show that cholesterol, when bound to one part of NPC1, can control the structural transitions of an 8-nm distant, different part of NPC1 protein called the N-terminal domain (NTD). Such long-range control of protein conformations (allostery), controls a wide range of cellular functions mediated by proteins. Fundamental molecular insights into the function of the NPC1 protein can potentially lead to better pharmaceutical interventions for the NPC diseases.
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Affiliation(s)
- Vikas Dubey
- PhyLife Physical Life Sciences, Department of Physics Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
- Department of Physics Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Behruz Bozorg
- PhyLife Physical Life Sciences, Department of Physics Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
- Department of Physics Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Daniel Wüstner
- PhyLife Physical Life Sciences, Department of Physics Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Himanshu Khandelia
- PhyLife Physical Life Sciences, Department of Physics Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
- Department of Physics Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
- MEMPHYS: Center for Biomembrane Physics, Odense M, Denmark
- * E-mail:
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22
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Yoon HJ, Jeong H, Lee HH, Jang S. Molecular dynamics study with mutation shows that N-terminal domain structural re-orientation in Niemann-Pick type C1 is required for proper alignment of cholesterol transport. J Neurochem 2020; 156:967-978. [PMID: 32880929 PMCID: PMC7461377 DOI: 10.1111/jnc.15150] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/30/2020] [Accepted: 07/30/2020] [Indexed: 11/27/2022]
Abstract
The lysosomal membrane protein Niemann‐Pick type C1 (NPC1) and Niemann‐Pick type C2 (NPC2) are main players of cholesterol control in the lysosome and it is known that the mutation on these proteins leads to the cholesterol trafficking‐related neurodegenerative disease, which is called the NPC disease. The mutation R518W or R518Q on the NPC1 is one of the type of disease‐related mutation that causes cholesterol transports to be cut in half, which results in the accumulation of cholesterol and lipids in the late endosomal/lysosomal compartment of the cell. Even though there has been significant progress with understanding the cholesterol transport by NPC1 in combination with NPC2, especially after the structural determination of the full‐length NPC1 in 2016, many details such as the interaction of the full‐length NPC1 with the NPC2, the molecular motions responsible for the cholesterol transport during and after this interaction, and the structure and the function relations of many mutations are still not well understood. In this study, we report the extensive molecular dynamics simulations in order to gain insight into the structure and the dynamics of NPC1 lumenal domain for the cholesterol transport and the disease behind the mutation (R518W). It was found that the mutation induces a structural shift of the N‐terminal domain, toward the loop region in the middle lumenal domain, which is believed to play a central role in the interaction with NPC2 protein, so the interaction with the NPC2 protein might be less favorable compared to the wild NPC1. Also, the simulation indicates the possible re‐orientation of the N‐terminal domain with both the wild and the R518W‐mutated NPC1 after receiving the cholesterol from the NPC2 that align to form an internal tunnel, which is a possible pose for further action in cholesterol trafficking. We believe the current study can provide a better understanding of the cholesterol transport by NPC1 especially the role of NTD of NPC1 in combination with NPC2 interactions.
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Affiliation(s)
- Hye-Jin Yoon
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Hyunah Jeong
- Department of Chemistry, Sejong University, Seoul, Republic of Korea
| | - Hyung Ho Lee
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Soonmin Jang
- Department of Chemistry, Sejong University, Seoul, Republic of Korea
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Chen H, Liu Y, Li X. Structure of human Dispatched-1 provides insights into Hedgehog ligand biogenesis. Life Sci Alliance 2020; 3:3/8/e202000776. [PMID: 32646883 PMCID: PMC7362390 DOI: 10.26508/lsa.202000776] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/23/2020] [Accepted: 06/24/2020] [Indexed: 12/19/2022] Open
Abstract
A cryo-EM structure of human Dispatched-1 reveals a unique open conformation of its extracellular domains for Hedgehog ligand binding. Hedgehog (HH) signaling is essential for metazoan development. The HH ligand is secreted into the extracellular space by a cell surface protein named Dispatched-1 (DISP1). Here, we report the cryo-EM structure of human DISP1 protein. DISP1 contains 12 transmembrane helices (TMs) and two extracellular domains (ECDs). Its ECDs reveal an open state, in contrast to its structural homologues PTCH1 and NPC1, whose extracellular/luminal domains adopt a closed state. The low-resolution structure of the DISP1 complex with dual lipid-modified HH ligand reveals how the ECDs of DISP1 engage with HH ligand. Moreover, several cholesterol-like molecules are found in the TMs, implying a transport-like function of DISP1.
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Affiliation(s)
- Hongwen Chen
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yang Liu
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xiaochun Li
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA .,Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
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