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Muzammil K, Hooshiar MH, Varmazyar S, Omar TM, Karim MM, Aadi S, Kalavi S, Yasamineh S. Potential use of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition and prevention method in viral infection. Microb Cell Fact 2024; 23:90. [PMID: 38528584 PMCID: PMC10962113 DOI: 10.1186/s12934-024-02355-8] [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: 01/09/2024] [Accepted: 03/03/2024] [Indexed: 03/27/2024] Open
Abstract
Cellular lipid membranes serve as the primary barrier preventing viral infection of the host cell and provide viruses with a critical initial point of contact. Occasionally, viruses can utilize lipids as viral receptors. Viruses depend significantly on lipid rafts for infection at virtually every stage of their life cycle. The pivotal role that proprotein convertase subtilisin/kexin Type 9 (PCSK9) plays in cholesterol homeostasis and atherosclerosis, primarily by post-transcriptionally regulating hepatic low-density lipoprotein receptor (LDLR) and promoting its lysosomal degradation, has garnered increasing interest. Conversely, using therapeutic, fully humanized antibodies to block PCSK9 leads to a significant reduction in high LDL cholesterol (LDL-C) levels. The Food and Drug Administration (FDA) has approved PCSK9 inhibitors, including inclisiran (Leqvio®), alirocumab (Praluent), and evolocumab (Repatha). At present, active immunization strategies targeting PCSK9 present a compelling substitute for passive immunization through the administration of antibodies. In addition to the current inquiry into the potential therapeutic application of PCSK9 inhibition in human immunodeficiency virus (HIV)-infected patients for hyperlipidemia associated with HIV and antiretroviral therapy (ART), preclinical research suggests that PCSK9 may also play a role in inhibiting hepatitis C virus (HCV) replication. Furthermore, PCSK9 inhibition has been suggested to protect against dengue virus (DENV) potentially and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viruses. Recent evidence regarding the impact of PCSK9 on a variety of viral infections, including HCV, HIV, DENV, and SARS-CoV-2, is examined in this article. As a result, PCSK9 inhibitors and vaccines may serve as viable host therapies for viral infections, as our research indicates that PCSK9 is significantly involved in the pathogenesis of viral infections.
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Affiliation(s)
- Khursheed Muzammil
- Department of Public Health, College of Applied Medical Sciences, King Khalid University, Khamis Mushait Campus, Abha, KSA, Saudi Arabia
| | | | - Shirin Varmazyar
- Department of Medicine, Shahroud Islamic azad university of medical sciences, Sharoud, Iran
| | - Thabit Moath Omar
- Department of Medical Laboratory Technics, Al-Noor University College, Nineveh, Iraq
| | - Manal Morad Karim
- Collage of Pharmacy, National University of Science and Technology, Dhi Qar, 64001, Iraq
| | - Sadeq Aadi
- College of Dentistry, Al-Mustaqbal University, Babylon, 51001, Iraq
| | - Shaylan Kalavi
- Department of Clinical Pharmacy, faculty of pharmacy, Islamic Azad University of Medical Sciences, Tehran, Iran.
| | - Saman Yasamineh
- Young Researchers and Elite Club, Tabriz Branch, Islamic Azad University, Tabriz, Iran.
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2
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Waeterschoot J, Gosselé W, Lemež Š, Casadevall I Solvas X. Artificial cells for in vivo biomedical applications through red blood cell biomimicry. Nat Commun 2024; 15:2504. [PMID: 38509073 PMCID: PMC10954685 DOI: 10.1038/s41467-024-46732-8] [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: 09/19/2023] [Accepted: 03/08/2024] [Indexed: 03/22/2024] Open
Abstract
Recent research in artificial cell production holds promise for the development of delivery agents with therapeutic effects akin to real cells. To succeed in these applications, these systems need to survive the circulatory conditions. In this review we present strategies that, inspired by the endurance of red blood cells, have enhanced the viability of large, cell-like vehicles for in vivo therapeutic use, particularly focusing on giant unilamellar vesicles. Insights from red blood cells can guide modifications that could transform these platforms into advanced drug delivery vehicles, showcasing biomimicry's potential in shaping the future of therapeutic applications.
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Affiliation(s)
- Jorik Waeterschoot
- Department of Biosystems - MeBioS, KU Leuven, Willem de Croylaan 42, 3001, Leuven, Belgium.
| | - Willemien Gosselé
- Department of Biosystems - MeBioS, KU Leuven, Willem de Croylaan 42, 3001, Leuven, Belgium
| | - Špela Lemež
- Department of Biosystems - MeBioS, KU Leuven, Willem de Croylaan 42, 3001, Leuven, Belgium
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3
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Gillard BK, Rosales C, Gotto AM, Pownall HJ. The pathophysiology of excess plasma-free cholesterol. Curr Opin Lipidol 2023; 34:278-286. [PMID: 37732779 PMCID: PMC10624414 DOI: 10.1097/mol.0000000000000899] [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] [Indexed: 09/22/2023]
Abstract
PURPOSE OF REVIEW Several large studies have shown increased mortality due to all-causes and to atherosclerotic cardiovascular disease. In most clinical settings, plasma HDL-cholesterol is determined as a sum of free cholesterol and cholesteryl ester, two molecules with vastly different metabolic itineraries. We examine the evidence supporting the concept that the pathological effects of elevations of plasma HDL-cholesterol are due to high levels of the free cholesterol component of HDL-C. RECENT FINDINGS In a small population of humans, a high plasma HDL-cholesterol is associated with increased mortality. Similar observations in the HDL-receptor deficient mouse (Scarb1 -/- ), a preclinical model of elevated HDL-C, suggests that the pathological component of HDL in these patients is an elevated plasma HDL-FC. SUMMARY Collective consideration of the human and mouse data suggests that clinical trials, especially in the setting of high plasma HDL, should measure free cholesterol and cholesteryl esters and not just total cholesterol.
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Affiliation(s)
- Baiba K. Gillard
- Center for Bioenergetics, Houston Methodist, Houston, Texas
- Weill Cornell Medicine, New York, New York, USA
| | - Corina Rosales
- Center for Bioenergetics, Houston Methodist, Houston, Texas
- Weill Cornell Medicine, New York, New York, USA
| | - Antonio M. Gotto
- Center for Bioenergetics, Houston Methodist, Houston, Texas
- Weill Cornell Medicine, New York, New York, USA
| | - Henry J. Pownall
- Center for Bioenergetics, Houston Methodist, Houston, Texas
- Weill Cornell Medicine, New York, New York, USA
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4
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Wang Z, Yelamanchili D, Liu J, Gotto AM, Rosales C, Gillard BK, Pownall HJ. Serum opacity factor normalizes erythrocyte morphology in Scarb1 -/- mice in an HDL-free cholesterol-dependent way. J Lipid Res 2023; 64:100456. [PMID: 37821077 PMCID: PMC10641538 DOI: 10.1016/j.jlr.2023.100456] [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: 08/09/2023] [Revised: 09/16/2023] [Accepted: 10/05/2023] [Indexed: 10/13/2023] Open
Abstract
Compared with WT mice, HDL receptor-deficient (Scarb1-/-) mice have higher plasma levels of free cholesterol (FC)-rich HDL and exhibit multiple pathologies associated with a high mol% FC in ovaries, platelets, and erythrocytes, which are reversed by lowering HDL. Bacterial serum opacity factor (SOF) catalyzes the opacification of plasma by targeting and quantitatively converting HDL to neo HDL (HDL remnant), a cholesterol ester-rich microemulsion, and lipid-free APOA1. SOF delivery with an adeno-associated virus (AAVSOF) constitutively lowers plasma HDL-FC and reverses female infertility in Scarb1-/- mice in an HDL-dependent way. We tested whether AAVSOF delivery to Scarb1-/- mice will normalize erythrocyte morphology in an HDL-FC-dependent way. We determined erythrocyte morphology and FC content (mol%) in three groups-WT, untreated Scarb1-/- (control), and Scarb1-/- mice receiving AAVSOF-and correlated these with their respective HDL-mol% FC. Plasma-, HDL-, and tissue-lipid compositions were also determined. Plasma- and HDL-mol% FC positively correlated across all groups. Among Scarb1-/- mice, AAVSOF treatment normalized reticulocyte number, erythrocyte morphology, and erythrocyte-mol% FC. Erythrocyte-mol% FC positively correlated with HDL-mol% FC and with both the number of reticulocytes and abnormal erythrocytes. AAVSOF treatment also reduced FC of extravascular tissues to a lesser extent. HDL-FC spontaneously transfers from plasma HDL to cell membranes. AAVSOF treatment lowers erythrocyte-FC and normalizes erythrocyte morphology and lipid composition by reducing HDL-mol% FC.
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Affiliation(s)
- Ziyi Wang
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Departments of Endocrinology and Xiangya Hospital, Central South University, Changsha, China
| | | | - Jing Liu
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Departments of Endocrinology and Cardiovascular Medicine, Xiangya Hospital, Central South University, Changsha, China
| | - Antonio M Gotto
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Corina Rosales
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Baiba K Gillard
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Henry J Pownall
- Center for Bioenergetics, Houston Methodist, Houston, TX, USA; Department of Medicine, Weill Cornell Medicine, New York, NY, USA.
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5
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Koh DHZ, Naito T, Na M, Yeap YJ, Rozario P, Zhong FL, Lim KL, Saheki Y. Visualization of accessible cholesterol using a GRAM domain-based biosensor. Nat Commun 2023; 14:6773. [PMID: 37880244 PMCID: PMC10600248 DOI: 10.1038/s41467-023-42498-7] [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: 06/23/2023] [Accepted: 10/12/2023] [Indexed: 10/27/2023] Open
Abstract
Cholesterol is important for membrane integrity and cell signaling, and dysregulation of the distribution of cellular cholesterol is associated with numerous diseases, including neurodegenerative disorders. While regulated transport of a specific pool of cholesterol, known as "accessible cholesterol", contributes to the maintenance of cellular cholesterol distribution and homeostasis, tools to monitor accessible cholesterol in live cells remain limited. Here, we engineer a highly sensitive accessible cholesterol biosensor by taking advantage of the cholesterol-sensing element (the GRAM domain) of an evolutionarily conserved lipid transfer protein, GRAMD1b. Using this cholesterol biosensor, which we call GRAM-W, we successfully visualize in real time the distribution of accessible cholesterol in many different cell types, including human keratinocytes and iPSC-derived neurons, and show differential dependencies on cholesterol biosynthesis and uptake for maintaining levels of accessible cholesterol. Furthermore, we combine GRAM-W with a dimerization-dependent fluorescent protein (ddFP) and establish a strategy for the ultrasensitive detection of accessible plasma membrane cholesterol. These tools will allow us to obtain important insights into the molecular mechanisms by which the distribution of cellular cholesterol is regulated.
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Affiliation(s)
- Dylan Hong Zheng Koh
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Minyoung Na
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Yee Jie Yeap
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Pritisha Rozario
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Franklin L Zhong
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
- Skin Research Institute of Singapore (SRIS), Singapore, 308232, Singapore
| | - Kah-Leong Lim
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
- National Neuroscience Institute, Singapore, 308433, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore.
- Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, 860-0811, Japan.
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6
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Naito T, Yang H, Koh DHZ, Mahajan D, Lu L, Saheki Y. Regulation of cellular cholesterol distribution via non-vesicular lipid transport at ER-Golgi contact sites. Nat Commun 2023; 14:5867. [PMID: 37735529 PMCID: PMC10514280 DOI: 10.1038/s41467-023-41213-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 08/28/2023] [Indexed: 09/23/2023] Open
Abstract
Abnormal distribution of cellular cholesterol is associated with numerous diseases, including cardiovascular and neurodegenerative diseases. Regulated transport of cholesterol is critical for maintaining its proper distribution in the cell, yet the underlying mechanisms remain unclear. Here, we show that lipid transfer proteins, namely ORP9, OSBP, and GRAMD1s/Asters (GRAMD1a/GRAMD1b/GRAMD1c), control non-vesicular cholesterol transport at points of contact between the ER and the trans-Golgi network (TGN), thereby maintaining cellular cholesterol distribution. ORP9 localizes to the TGN via interaction between its tandem α-helices and ORP10/ORP11. ORP9 extracts PI4P from the TGN to prevent its overaccumulation and suppresses OSBP-mediated PI4P-driven cholesterol transport to the Golgi. By contrast, GRAMD1s transport excess cholesterol from the Golgi to the ER, thereby preventing its build-up. Cells lacking ORP9 exhibit accumulation of cholesterol at the Golgi, which is further enhanced by additional depletion of GRAMD1s with major accumulation in the plasma membrane. This is accompanied by chronic activation of the SREBP-2 signalling pathway. Our findings reveal the importance of regulated lipid transport at ER-Golgi contacts for maintaining cellular cholesterol distribution and homeostasis.
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Affiliation(s)
- Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Haoning Yang
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Dylan Hong Zheng Koh
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore
| | - Divyanshu Mahajan
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - Lei Lu
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, 308232, Singapore.
- Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, 860-0811, Japan.
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7
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Shaw TR, Wisser KC, Schaffner TA, Gaffney AD, Machta BB, Veatch SL. Chemical potential measurements constrain models of cholesterol-phosphatidylcholine interactions. Biophys J 2023; 122:1105-1117. [PMID: 36785512 PMCID: PMC10111267 DOI: 10.1016/j.bpj.2023.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 12/12/2022] [Accepted: 02/01/2023] [Indexed: 02/15/2023] Open
Abstract
Bilayer membranes composed of cholesterol and phospholipids exhibit diverse forms of nonideal mixing. In particular, many previous studies document macroscopic liquid-liquid phase separation as well as nanometer-scale heterogeneity in membranes of phosphatidylcholine (PC) lipids and cholesterol. Here, we present experimental measurements of cholesterol chemical potential (μc) in binary membranes containing dioleoyl PC (DOPC), 1-palmitoyl-2-oleoyl PC (POPC), or dipalmitoyl PC (DPPC), and in ternary membranes of DOPC and DPPC, referenced to crystalline cholesterol. μc is the thermodynamic quantity that dictates the availability of cholesterol to bind other factors, and notably must be equal between coexisting phases of a phase separated mixture. It is simply related to concentration under conditions of ideal mixing, but is far from ideal for the majority of lipid mixtures investigated here. Measurements of μc can vary with phospholipid composition by 1.5 kBT at constant cholesterol mole fraction implying a more than fivefold change in its availability for binding receptors and other reactions. Experimental measurements are fit to thermodynamic models including cholesterol-DPPC complexes or pairwise interactions between lipid species to provide intuition about the magnitude of interactions. These findings reinforce that μc depends on membrane composition overall, suggesting avenues for cells to alter the availability of cholesterol without varying cholesterol concentration.
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Affiliation(s)
- Thomas R Shaw
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan; Program in Applied Physics, University of Michigan, Ann Arbor, Michigan
| | | | | | - Anna D Gaffney
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan
| | | | - Sarah L Veatch
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan; Program in Applied Physics, University of Michigan, Ann Arbor, Michigan.
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8
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Lange Y, Tabei SMA, Steck TL. A basic model for the association of ligands with membrane cholesterol: application to cytolysin binding. J Lipid Res 2023; 64:100344. [PMID: 36791915 PMCID: PMC10119614 DOI: 10.1016/j.jlr.2023.100344] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/19/2023] [Accepted: 02/07/2023] [Indexed: 02/16/2023] Open
Abstract
Almost all the cholesterol in cellular membranes is associated with phospholipids in simple stoichiometric complexes. This limits the binding of sterol ligands such as filipin and Perfringolysin O (PFO) to a small fraction of the total. We offer a simple mathematical model that characterizes this complexity. It posits that the cholesterol accessible to ligands has two forms: active cholesterol, which is that not complexed with phospholipids; and extractable cholesterol, that which ligands can capture competitively from the phospholipid complexes. Simulations based on the model match published data for the association of PFO oligomers with liposomes, plasma membranes and the isolated endoplasmic reticulum. The model shows how the binding of a probe greatly underestimates cholesterol abundance when its affinity for the sterol is so weak that it competes poorly with the membrane phospholipids. Two examples are the under-staining of plasma membranes by filipin and the failure of domain D4 of PFO to label their cytoplasmic leaflets. Conversely, the exaggerated staining of endolysosomes suggests that their cholesterol, being uncomplexed, is readily available. The model is also applicable to the association of cholesterol with intrinsic membrane proteins. For example, it supports the hypothesis that the sharp threshold in the regulation of homeostatic ER proteins by cholesterol derives from the cooperativity of their binding to the sterol weakly held by the phospholipid. § Thus, the model explicates the complexity inherent in the binding of ligands like PFO and filipin to the small accessible fraction of membrane cholesterol.
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Affiliation(s)
- Yvonne Lange
- 1Department of Pathology, Rush University Medical Center, Chicago, Il 60612, USA.
| | - S M Ali Tabei
- Department of Physics, University of Northern Iowa, Cedar Falls, Iowa 50614, USA
| | - Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Il 60637, USA
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9
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Heisler DB, Johnson KA, Ma DH, Ohlson MB, Zhang L, Tran M, Corley CD, Abrams ME, McDonald JG, Schoggins JW, Alto NM, Radhakrishnan A. A concerted mechanism involving ACAT and SREBPs by which oxysterols deplete accessible cholesterol to restrict microbial infection. eLife 2023; 12:e83534. [PMID: 36695568 PMCID: PMC9925056 DOI: 10.7554/elife.83534] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 01/25/2023] [Indexed: 01/26/2023] Open
Abstract
Most of the cholesterol in the plasma membranes (PMs) of animal cells is sequestered through interactions with phospholipids and transmembrane domains of proteins. However, as cholesterol concentration rises above the PM's sequestration capacity, a new pool of cholesterol, called accessible cholesterol, emerges. The transport of accessible cholesterol between the PM and the endoplasmic reticulum (ER) is critical to maintain cholesterol homeostasis. This pathway has also been implicated in the suppression of both bacterial and viral pathogens by immunomodulatory oxysterols. Here, we describe a mechanism of depletion of accessible cholesterol from PMs by the oxysterol 25-hydroxycholesterol (25HC). We show that 25HC-mediated activation of acyl coenzyme A: cholesterol acyltransferase (ACAT) in the ER creates an imbalance in the equilibrium distribution of accessible cholesterol between the ER and PM. This imbalance triggers the rapid internalization of accessible cholesterol from the PM, and this depletion is sustained for long periods of time through 25HC-mediated suppression of SREBPs and continued activation of ACAT. In support of a physiological role for this mechanism, 25HC failed to suppress Zika virus and human coronavirus infection in ACAT-deficient cells, and Listeria monocytogenes infection in ACAT-deficient cells and mice. We propose that selective depletion of accessible PM cholesterol triggered by ACAT activation and sustained through SREBP suppression underpins the immunological activities of 25HC and a functionally related class of oxysterols.
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Affiliation(s)
- David B Heisler
- Department of Microbiology, The University of Texas Southwestern Medical CenterDallasUnited States
| | - Kristen A Johnson
- Department of Molecular Genetics, The University of Texas Southwestern Medical CenterDallasUnited States
| | - Duo H Ma
- Department of Microbiology, The University of Texas Southwestern Medical CenterDallasUnited States
- Department of Molecular Genetics, The University of Texas Southwestern Medical CenterDallasUnited States
| | - Maikke B Ohlson
- Department of Microbiology, The University of Texas Southwestern Medical CenterDallasUnited States
| | - Lishu Zhang
- Department of Microbiology, The University of Texas Southwestern Medical CenterDallasUnited States
| | - Michelle Tran
- Department of Molecular Genetics, The University of Texas Southwestern Medical CenterDallasUnited States
| | - Chase D Corley
- Department of Molecular Genetics, The University of Texas Southwestern Medical CenterDallasUnited States
| | - Michael E Abrams
- Department of Microbiology, The University of Texas Southwestern Medical CenterDallasUnited States
| | - Jeffrey G McDonald
- Department of Molecular Genetics, The University of Texas Southwestern Medical CenterDallasUnited States
| | - John W Schoggins
- Department of Microbiology, The University of Texas Southwestern Medical CenterDallasUnited States
| | - Neal M Alto
- Department of Microbiology, The University of Texas Southwestern Medical CenterDallasUnited States
| | - Arun Radhakrishnan
- Department of Molecular Genetics, The University of Texas Southwestern Medical CenterDallasUnited States
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Niesor EJ, Nader E, Perez A, Lamour F, Benghozi R, Remaley A, Thein SL, Connes P. Red Blood Cell Membrane Cholesterol May Be a Key Regulator of Sickle Cell Disease Microvascular Complications. MEMBRANES 2022; 12:1134. [PMID: 36422126 PMCID: PMC9694375 DOI: 10.3390/membranes12111134] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/06/2022] [Accepted: 11/07/2022] [Indexed: 06/16/2023]
Abstract
Cell membrane lipid composition, especially cholesterol, affects many functions of embedded enzymes, transporters and receptors in red blood cells (RBC). High membrane cholesterol content affects the RBCs' main vital function, O2 and CO2 transport and delivery, with consequences on peripheral tissue physiology and pathology. A high degree of deformability of RBCs is required to accommodate the size of micro-vessels with diameters significantly lower than RBCs. The potential therapeutic role of high-density lipoproteins (HDL) in the removal of cholesterol and its activity regarding maintenance of an optimal concentration of RBC membrane cholesterol have not been well investigated. On the contrary, the focus for HDL research has mainly been on the clearance of cholesterol accumulated in atherosclerotic macrophages and plaques. Since all interventions aiming at decreasing cardiovascular diseases by increasing the plasma level of HDL cholesterol have failed so far in large outcome studies, we reviewed the potential role of HDL to remove excess membrane cholesterol from RBC, especially in sickle cell disease (SCD). Indeed, abundant literature supports a consistent decrease in cholesterol transported by all plasma lipoproteins in SCD, in addition to HDL, low- (LDL) and very low-density lipoproteins (VLDL). Unexpectedly, these decreases in plasma were associated with an increase in RBC membrane cholesterol. The concentration and activity of the main enzyme involved in the removal of cholesterol and generation of large HDL particles-lecithin cholesterol ester transferase (LCAT)-are also significantly decreased in SCD. These observations might partially explain the decrease in RBC deformability, diminished gas exchange and tendency of RBCs to aggregate in SCD. We showed that incubation of RBC from SCD patients with human HDL or the HDL-mimetic peptide Fx5A improves the impaired RBC deformability and decreases intracellular reactive oxygen species levels. We propose that the main physiological role of HDL is to regulate the cholesterol/phospholipid ratio (C/PL), which is fundamental to the transport of oxygen and its delivery to peripheral tissues.
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Affiliation(s)
| | - Elie Nader
- Laboratory LIBM EA7424, Vascular Biology and Red Blood Cell Team, University of Lyon, 69007 Lyon, France
| | - Anne Perez
- Hartis Pharma SA Nyon, 1260 Nyon, Switzerland
| | | | | | - Alan Remaley
- National Institutes of Health, Bethesda, MD 20814, USA
| | | | - Philippe Connes
- Laboratory LIBM EA7424, Vascular Biology and Red Blood Cell Team, University of Lyon, 69007 Lyon, France
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11
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Yamaji-Hasegawa A, Murate M, Inaba T, Dohmae N, Sato M, Fujimori F, Sako Y, Greimel P, Kobayashi T. A novel sterol-binding protein reveals heterogeneous cholesterol distribution in neurite outgrowth and in late endosomes/lysosomes. Cell Mol Life Sci 2022; 79:324. [PMID: 35644822 PMCID: PMC11072113 DOI: 10.1007/s00018-022-04339-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 04/26/2022] [Accepted: 04/29/2022] [Indexed: 11/24/2022]
Abstract
We identified a mushroom-derived protein, maistero-2 that specifically binds 3-hydroxy sterol including cholesterol (Chol). Maistero-2 bound lipid mixture in Chol-dependent manner with a binding threshold of around 30%. Changing lipid composition did not significantly affect the threshold concentration. EGFP-maistero-2 labeled cell surface and intracellular organelle Chol with higher sensitivity than that of well-established Chol probe, D4 fragment of perfringolysin O. EGFP-maistero-2 revealed increase of cell surface Chol during neurite outgrowth and heterogeneous Chol distribution between CD63-positive and LAMP1-positive late endosomes/lysosomes. The absence of strictly conserved Thr-Leu pair present in Chol-dependent cytolysins suggests a distinct Chol-binding mechanism for maistero-2.
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Affiliation(s)
| | - Motohide Murate
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- UMR 7021, CNRS, Université de Strasbourg, 67401, Illkirch, France
| | - Takehiko Inaba
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN CSRS, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Masayuki Sato
- Yukiguni Maitake Co, Ltd. Yokawa 89, Minamiuonuma, Niigata, 949-6695, Japan
| | - Fumihiro Fujimori
- Laboratory of Biological Science and Technology, Tokyo Kasei University, 1-18-1 Kaga, Itabashi, Tokyo, 173-8062, Japan
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Peter Greimel
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Toshihide Kobayashi
- Lipid Biology Laboratory, RIKEN, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
- Cellular Informatics Laboratory, RIKEN CPR, 2-1, Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
- UMR 7021, CNRS, Université de Strasbourg, 67401, Illkirch, France.
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12
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Ray S, Roth R, Keyel PA. Membrane repair triggered by cholesterol-dependent cytolysins is activated by mixed lineage kinases and MEK. SCIENCE ADVANCES 2022; 8:eabl6367. [PMID: 35294243 PMCID: PMC8926344 DOI: 10.1126/sciadv.abl6367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Repair of plasma membranes damaged by bacterial pore-forming toxins, such as streptolysin O or perfringolysin O, during septic cardiomyopathy or necrotizing soft tissue infections is mediated by several protein families. However, the activation of these proteins downstream of ion influx is poorly understood. Here, we demonstrate that following membrane perforation by bacterial cholesterol-dependent cytolysins, calcium influx activates mixed lineage kinase 3 independently of protein kinase C or ceramide generation. Mixed lineage kinase 3 uncouples mitogen-activated kinase kinase (MEK) and extracellular-regulated kinase (ERK) signaling. MEK signals via an ERK-independent pathway to promote rapid annexin A2 membrane recruitment and enhance microvesicle shedding. This pathway accounted for 70% of all calcium ion-dependent repair responses to streptolysin O and perfringolysin O, but only 50% of repair to intermedilysin. We conclude that mixed lineage kinase signaling via MEK coordinates microvesicle shedding, which is critical for cellular survival against cholesterol-dependent cytolysins.
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Affiliation(s)
- Sucharit Ray
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Robyn Roth
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Peter A. Keyel
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
- Corresponding author.
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13
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Sphingomyelin-Sequestered Cholesterol Domain Recruits Formin-Binding Protein 17 for Constricting Clathrin-Coated Pits in Influenza Virus Entry. J Virol 2022; 96:e0181321. [PMID: 35020471 DOI: 10.1128/jvi.01813-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Influenza A virus (IAV) is a global health threat. The cellular endocytic machineries harnessed by IAV remain elusive. Here, by tracking single IAV particles and quantifying the internalized IAV, we found that the sphingomyelin (SM)-sequestered cholesterol, but not the accessible cholesterol, is essential for the clathrin-mediated endocytosis (CME) of IAV. The clathrin-independent endocytosis of IAV is cholesterol-independent. Whereas, the CME of transferrin depends on SM-sequestered cholesterol and accessible cholesterol. Furthermore, three-color single-virus tracking and electron microscopy showed that the SM-cholesterol complex nanodomain is recruited to the IAV-containing clathrin-coated structure (CCS) and facilitates neck constriction of the IAV-containing CCS. Meanwhile, formin-binding protein 17 (FBP17), a membrane-bending protein which activates actin nucleation, is recruited to IAV-CCS complex in a manner dependent on the SM-cholesterol complex. We propose that the SM-cholesterol nanodomain at the neck of CCS recruits FBP17 to induce neck constriction by activating actin assembly. These results unequivocally show the physiological importance of the SM-cholesterol complex in IAV entry. Importance: IAV infects the cells by harnessing cellular endocytic machineries. Better understanding of the cellular machineries used for its entry might lead to the development of antiviral strategies, and would also provide important insights into physiological endocytic processes. This work demonstrated that a special pool of cholesterol in plasma membrane, SM-sequestered cholesterol, recruits FBP17 for the constriction of clathrin-coated pits in IAV entry. Meanwhile, the clathrin-independent cell entry of IAV is cholesterol-independent. The internalization of transferrin, the gold-standard cargo endocytosed solely via CME, is much less dependent on the SM-cholesterol complex. These results would provide new insights into IAV infection and pathway/cargo-specific involvement of cholesterol pool(s).
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14
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Vecka M, Dušejovská M, Staňková B, Rychlík I, Žák A. A Matched Case-Control Study of Noncholesterol Sterols and Fatty Acids in Chronic Hemodialysis Patients. Metabolites 2021; 11:774. [PMID: 34822432 PMCID: PMC8618803 DOI: 10.3390/metabo11110774] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 12/17/2022] Open
Abstract
Dyslipidemia is common among patients on hemodialysis, but its etiology is not fully understood. Although changes in cholesterol homeostasis and fatty acid metabolism play an important role during dialysis, the interaction of these metabolic pathways has yet to be studied in sufficient detail. In this study, we enrolled 26 patients on maintenance hemodialysis treatment (high-volume hemodiafiltration, HV HDF) without statin therapy (17 men/9 women) and an age/gender-matched group of 26 individuals without signs of nephropathy. The HV-HDF group exhibited more frequent signs of cardiovascular disease, disturbed saccharide metabolism, and altered lipoprotein profiles, manifesting in lower HDL-C, and raised concentrations of IDL-C and apoB-48 (all p < 0.01). HV-HDF patients had higher levels of campesterol (p < 0.01) and β-sitosterol (p = 0.06), both surrogate markers of cholesterol absorption and unchanged lathosterol concentrations. Fatty acid (FA) profiles were changed mostly in cholesteryl esters, with a higher content of saturated and n-3 polyunsaturated fatty acids (PUFA) in the HV-HDF group. However, n-6 PUFA in cholesteryl esters were less abundant (p < 0.001) in the HV-HDF group. Hemodialysis during end-stage kidney disease induces changes associated with higher absorption of cholesterol and disturbed lipoprotein metabolism. Changes in fatty acid metabolism reflect the combined effect of renal insufficiency and its comorbidities, mostly insulin resistance.
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Affiliation(s)
- Marek Vecka
- Fourth Department of Internal Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, U Nemocnice 2, 128 08 Prague, Czech Republic; (M.D.); (B.S.); (A.Ž.)
- Institute of Clinical Chemistry and Laboratory Diagnostics, First Faculty of Medicine, Charles University and General University Hospital in Prague, Na Bojišti 3, 121 08 Prague, Czech Republic
| | - Magdalena Dušejovská
- Fourth Department of Internal Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, U Nemocnice 2, 128 08 Prague, Czech Republic; (M.D.); (B.S.); (A.Ž.)
| | - Barbora Staňková
- Fourth Department of Internal Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, U Nemocnice 2, 128 08 Prague, Czech Republic; (M.D.); (B.S.); (A.Ž.)
| | - Ivan Rychlík
- Department of Internal Medicine, Third Faculty of Medicine, Charles University and University Hospital Královské Vinohrady, Šrobárova 50, 100 34 Prague, Czech Republic;
| | - Aleš Žák
- Fourth Department of Internal Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, U Nemocnice 2, 128 08 Prague, Czech Republic; (M.D.); (B.S.); (A.Ž.)
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15
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Steck TL, Tabei SMA, Lange Y. A basic model for cell cholesterol homeostasis. Traffic 2021; 22:471-481. [PMID: 34528339 DOI: 10.1111/tra.12816] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/26/2021] [Accepted: 09/13/2021] [Indexed: 11/30/2022]
Abstract
Cells manage their cholesterol by negative feedback using a battery of sterol-responsive proteins. How these activities are coordinated so as to specify the abundance and distribution of the sterol is unclear. We present a simple mathematical model that addresses this question. It assumes that almost all of the cholesterol is associated with phospholipids in stoichiometric complexes. A small fraction of the sterol is uncomplexed and thermodynamically active. It equilibrates among the organelles, setting their sterol level according to the affinity of their phospholipids. The activity of the homeostatic proteins in the cytoplasmic membranes is then set by their fractional saturation with uncomplexed cholesterol in competition with the phospholipids. The high-affinity phospholipids in the plasma membrane (PM) are filled to near stoichiometric equivalence, giving it most of the cell sterol. Notably, the affinity of the phospholipids in the endomembranes (EMs) is lower by orders of magnitude than that of the phospholipids in the PM. Thus, the small amount of sterol in the EMs rests far below stoichiometric capacity. Simulations match a variety of experimental data. The model captures the essence of cell cholesterol homeostasis, makes coherent a diverse set of experimental findings, provides a surprising prediction and suggests new experiments.
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Affiliation(s)
- Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA
| | - S M Ali Tabei
- Department of Physics, University of Northern Iowa, Cedar Falls, Iowa, USA
| | - Yvonne Lange
- Department of Pathology, Rush University Medical Center, Chicago, Illinois, USA
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16
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Schoop V, Martello A, Eden ER, Höglinger D. Cellular cholesterol and how to find it. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158989. [PMID: 34118431 DOI: 10.1016/j.bbalip.2021.158989] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 01/06/2023]
Abstract
Cholesterol is an essential component of eukaryotic cellular membranes. Information about its subcellular localization and transport pathways inside cells are key for the understanding and treatment of cholesterol-related diseases. In this review we give an overview over the most commonly used methods that contributed to our current understanding of subcellular cholesterol localization and transport routes. First, we discuss methods that provide insights into cholesterol metabolism based on readouts of downstream effects such as esterification. Subsequently, we focus on the use of cholesterol-binding molecules as probes that facilitate visualization and quantification of sterols inside of cells. Finally, we explore different analogues of cholesterol which, when taken up by living cells, are integrated and transported in a similar fashion as endogenous sterols. Taken together, we highlight the challenges and advantages of each method such that researchers studying aspects of cholesterol transport may choose the most pertinent approach for their problem.
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Affiliation(s)
- Valentin Schoop
- Heidelberg University Biochemistry Center (BZH), 69120 Heidelberg, Germany
| | - Andrea Martello
- University College London (UCL), Institute of Ophthalmology, EC1V 9EL London, United Kingdom
| | - Emily R Eden
- University College London (UCL), Institute of Ophthalmology, EC1V 9EL London, United Kingdom
| | - Doris Höglinger
- Heidelberg University Biochemistry Center (BZH), 69120 Heidelberg, Germany.
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17
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Naito T, Saheki Y. GRAMD1-mediated accessible cholesterol sensing and transport. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158957. [PMID: 33932585 DOI: 10.1016/j.bbalip.2021.158957] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/09/2021] [Accepted: 04/19/2021] [Indexed: 01/19/2023]
Abstract
Cholesterol, an essential lipid for cell signaling and structural integrity of cellular membranes, is highly enriched in the plasma membrane (PM). However, the regulatory mechanisms that control its biosynthesis and uptake both reside in the endoplasmic reticulum (ER). Thus, the ER needs to constantly monitor the levels of PM cholesterol. This is in part mediated by regulated transport of a biochemically defined pool of cholesterol, termed "accessible" cholesterol, from the PM to the ER via evolutionarily conserved ER-anchored lipid transfer proteins, the GRAMD1s/Asters (GRAMD1a/1b/1c) (Lam/Ltc proteins in yeast). GRAMD1s possess cytosolically exposed GRAM domain and StART-like domain followed by a transmembrane ER anchor. They form homo- and hetero-meric complexes and move to the contacts formed between the ER and the PM by sensing a transient expansion of the accessible pool of cholesterol in the PM via the GRAM domain and facilitate its extraction and transport to the ER via the StART-like domain. The GRAMD1b GRAM domain possesses distinct, but synergistic sites, for recognizing accessible cholesterol and anionic lipids, including phosphatidylserine, within the PM. This property of the GRAM domain contributes to regulated tethering of the PM to ER membrane where GRAMD1s are anchored and fine-tunes StART-like domain-dependent accessible cholesterol transport. Thus, cells use GRAMD1s to sense the levels of cholesterol in the PM and regulate transport of accessible PM cholesterol to the ER in order to maintain cholesterol homeostasis.
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Affiliation(s)
- Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological University, 308232, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, 308232, Singapore; Institute of Resource Development and Analysis, Kumamoto University, Kumamoto 860-0811, Japan.
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18
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Darnet S, Blary A, Chevalier Q, Schaller H. Phytosterol Profiles, Genomes and Enzymes - An Overview. FRONTIERS IN PLANT SCIENCE 2021; 12:665206. [PMID: 34093623 PMCID: PMC8172173 DOI: 10.3389/fpls.2021.665206] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 04/20/2021] [Indexed: 05/12/2023]
Abstract
The remarkable diversity of sterol biosynthetic capacities described in living organisms is enriched at a fast pace by a growing number of sequenced genomes. Whereas analytical chemistry has produced a wealth of sterol profiles of species in diverse taxonomic groups including seed and non-seed plants, algae, phytoplanktonic species and other unicellular eukaryotes, functional assays and validation of candidate genes unveils new enzymes and new pathways besides canonical biosynthetic schemes. An overview of the current landscape of sterol pathways in the tree of life is tentatively assembled in a series of sterolotypes that encompass major groups and provides also peculiar features of sterol profiles in bacteria, fungi, plants, and algae.
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Affiliation(s)
| | | | | | - Hubert Schaller
- Plant Isoprenoid Biology Team, Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France
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19
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Tomishige N, Murate M, Didier P, Richert L, Mély Y, Kobayashi T. The use of pore-forming toxins to image lipids and lipid domains. Methods Enzymol 2021; 649:503-542. [PMID: 33712198 DOI: 10.1016/bs.mie.2021.01.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Very few proteins are reported to bind specific lipids. Because of the high selectivity and strong binding to specific lipids, lipid-targeting pore forming toxins (PFTs) have been employed to study the distribution of lipids in cell- and model-membranes. Non-toxic and monomeric PFT-derivatives are especially useful to study living cells. In this chapter we highlight sphingomyelin (SM)-binding PFT, lysenin (Lys), its derivatives, and newly identified SM/cholesterol binding protein, nakanori. We describe the preparation of non-toxic mutant of Lys (NT-Lys) and its application in optical and super resolution microscopy. We also discuss the observation of nanometer scale lipid domains labeled with nakanori and maltose-binding protein (MBP)-Lys in electron microscopy.
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Affiliation(s)
| | | | - Pascal Didier
- UMR 7021 CNRS, Université de Strasbourg, Illkirch, France
| | | | - Yves Mély
- UMR 7021 CNRS, Université de Strasbourg, Illkirch, France
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20
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Ercan B, Naito T, Koh DHZ, Dharmawan D, Saheki Y. Molecular basis of accessible plasma membrane cholesterol recognition by the GRAM domain of GRAMD1b. EMBO J 2021; 40:e106524. [PMID: 33604931 PMCID: PMC7957428 DOI: 10.15252/embj.2020106524] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 12/16/2020] [Accepted: 01/08/2021] [Indexed: 12/25/2022] Open
Abstract
Cholesterol is essential for cell physiology. Transport of the "accessible" pool of cholesterol from the plasma membrane (PM) to the endoplasmic reticulum (ER) by ER-localized GRAMD1 proteins (GRAMD1a/1b/1c) contributes to cholesterol homeostasis. However, how cells detect accessible cholesterol within the PM remains unclear. We show that the GRAM domain of GRAMD1b, a coincidence detector for anionic lipids, including phosphatidylserine (PS), and cholesterol, possesses distinct but synergistic sites for sensing accessible cholesterol and anionic lipids. We find that a mutation within the GRAM domain of GRAMD1b that is associated with intellectual disability in humans specifically impairs cholesterol sensing. In addition, we identified another point mutation within this domain that enhances cholesterol sensitivity without altering its PS sensitivity. Cell-free reconstitution and cell-based assays revealed that the ability of the GRAM domain to sense accessible cholesterol regulates membrane tethering and determines the rate of cholesterol transport by GRAMD1b. Thus, cells detect the codistribution of accessible cholesterol and anionic lipids in the PM and fine-tune the non-vesicular transport of PM cholesterol to the ER via GRAMD1s.
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Affiliation(s)
- Bilge Ercan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | | | - Dennis Dharmawan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore.,Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Japan
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21
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Zheng Koh DH, Saheki Y. Regulation of Plasma Membrane Sterol Homeostasis by Nonvesicular Lipid Transport. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2021; 4:25152564211042451. [PMID: 37366378 PMCID: PMC10259818 DOI: 10.1177/25152564211042451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Sterol contributes to the structural integrity of cellular membranes and plays an important role in the regulation of cell signaling in eukaryotes. It is either produced in the endoplasmic reticulum or taken up from the extracellular environment. In most eukaryotic cells, however, the majority of sterol is enriched in the plasma membrane. Thus, the transport of sterol between the plasma membrane and other organelles, including the endoplasmic reticulum, is crucial for maintaining sterol homeostasis. While vesicular transport that relies on membrane budding and fusion reactions plays an important role in bulk sterol transport, this mode of transport is slow and non-selective. Growing evidence suggests a critical role of nonvesicular transport mediated by evolutionarily conserved families of lipid transfer proteins in more rapid and selective delivery of sterol. Some lipid transfer proteins act primarily at the sites of contacts formed between the endoplasmic reticulum and other organelles or the plasma membrane without membrane fusion. In this review, we describe the similarities and differences of sterol biosynthesis and uptake in mammals and yeast and discuss the role of their lipid transfer proteins in maintaining plasma membrane sterol homeostasis.
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Affiliation(s)
- Dylan Hong Zheng Koh
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 308232, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 308232, Singapore
- Institute of Resource Development and
Analysis, Kumamoto University, Kumamoto 860-0811, Japan
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22
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Zhang Y, Li Q, Dong M, Han X. Effect of cholesterol on the fluidity of supported lipid bilayers. Colloids Surf B Biointerfaces 2020; 196:111353. [DOI: 10.1016/j.colsurfb.2020.111353] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 01/12/2023]
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23
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Holkar A, Ghodke S, Bangde P, Dandekar P, Jain R. Fluorescence-Based Detection of Cholesterol Using Inclusion Complex of Hydroxypropyl-β-Cyclodextrin and l-Tryptophan as the Fluorescence Probe. J Pharm Innov 2020. [DOI: 10.1007/s12247-020-09503-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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24
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Lange Y, Steck TL. Active cholesterol 20 years on. Traffic 2020; 21:662-674. [PMID: 32930466 DOI: 10.1111/tra.12762] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/08/2020] [Accepted: 09/10/2020] [Indexed: 12/13/2022]
Abstract
This review considers the following hypotheses, some well-supported and some speculative. Almost all of the sterol molecules in plasma membranes are associated with bilayer phospholipids in complexes of varied strength and stoichiometry. These complexes underlie many of the material properties of the bilayer. The small fraction of cholesterol molecules exceeding the binding capacity of the phospholipids is thermodynamically active and serves diverse functions. It circulates briskly among the cell membranes, particularly through contact sites linking the organelles. Active cholesterol provides the upstream feedback signal to multiple mechanisms governing plasma membrane homeostasis, pegging the sterol level to a threshold set by its phospholipids. Active cholesterol could also be the cargo for various inter-organelle transporters and the form excreted from cells by reverse transport. Furthermore, it is integral to the function of caveolae; a mediator of Hedgehog regulation; and a ligand for the binding of cytolytic toxins to membranes. Active cholesterol modulates a variety of plasma membrane proteins-receptors, channels and transporters-at least in vitro.
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Affiliation(s)
- Yvonne Lange
- Department of Pathology, Rush University Medical Center, Chicago, Illinois, USA
| | - Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA
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25
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Penkauskas T, Zentelyte A, Ganpule S, Valincius G, Preta G. Pleiotropic effects of statins via interaction with the lipid bilayer: A combined approach. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183306. [DOI: 10.1016/j.bbamem.2020.183306] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/18/2020] [Accepted: 04/07/2020] [Indexed: 12/25/2022]
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26
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Chimalapati S, de Souza Santos M, Lafrance AE, Ray A, Lee WR, Rivera-Cancel G, Vale G, Pawlowski K, Mitsche MA, McDonald JG, Liou J, Orth K. Vibrio deploys type 2 secreted lipase to esterify cholesterol with host fatty acids and mediate cell egress. eLife 2020; 9:58057. [PMID: 32808593 PMCID: PMC7434443 DOI: 10.7554/elife.58057] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 07/28/2020] [Indexed: 12/23/2022] Open
Abstract
Pathogens find diverse niches for survival including inside a host cell where replication occurs in a relatively protective environment. Vibrio parahaemolyticus is a facultative intracellular pathogen that uses its type 3 secretion system 2 (T3SS2) to invade and replicate inside host cells. Analysis of the T3SS2 pathogenicity island encoding the T3SS2 appeared to lack a mechanism for egress of this bacterium from the invaded host cell. Using a combination of molecular tools, we found that VPA0226, a constitutively secreted lipase, is required for escape of V. parahaemolyticus from the host cells. This lipase must be delivered into the host cytoplasm where it preferentially uses fatty acids associated with innate immune response to esterify cholesterol, weakening the plasma membrane and allowing egress of the bacteria. This study reveals the resourcefulness of microbes and the interplay between virulence systems and host cell resources to evolve an ingenious scheme for survival and escape.
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Affiliation(s)
- Suneeta Chimalapati
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States
| | - Marcela de Souza Santos
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Alexander E Lafrance
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Ann Ray
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Wan-Ru Lee
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Giomar Rivera-Cancel
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Gonçalo Vale
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, United States
| | - Krzysztof Pawlowski
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States.,Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Warsaw, Poland
| | - Matthew A Mitsche
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jeffrey G McDonald
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jen Liou
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
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27
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Zhou QD, Chi X, Lee MS, Hsieh WY, Mkrtchyan JJ, Feng AC, He C, York AG, Bui VL, Kronenberger EB, Ferrari A, Xiao X, Daly AE, Tarling EJ, Damoiseaux R, Scumpia PO, Smale ST, Williams KJ, Tontonoz P, Bensinger SJ. Interferon-mediated reprogramming of membrane cholesterol to evade bacterial toxins. Nat Immunol 2020; 21:746-755. [PMID: 32514064 PMCID: PMC7778040 DOI: 10.1038/s41590-020-0695-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/28/2020] [Indexed: 12/21/2022]
Abstract
Plasma membranes of animal cells are enriched for cholesterol. Cholesterol-dependent cytolysins (CDCs) are pore-forming toxins secreted by bacteria that target membrane cholesterol for their effector function. Phagocytes are essential for clearance of CDC-producing bacteria; however, the mechanisms by which these cells evade the deleterious effects of CDCs are largely unknown. Here, we report that interferon (IFN) signals convey resistance to CDC-induced pores on macrophages and neutrophils. We traced IFN-mediated resistance to CDCs to the rapid modulation of a specific pool of cholesterol in the plasma membrane of macrophages without changes to total cholesterol levels. Resistance to CDC-induced pore formation requires the production of the oxysterol 25-hydroxycholesterol (25HC), inhibition of cholesterol synthesis and redistribution of cholesterol to an esterified cholesterol pool. Accordingly, blocking the ability of IFN to reprogram cholesterol metabolism abrogates cellular protection and renders mice more susceptible to CDC-induced tissue damage. These studies illuminate targeted regulation of membrane cholesterol content as a host defense strategy.
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Affiliation(s)
- Quan D Zhou
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA.,Department of Surgical Oncology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, P.R. China
| | - Xun Chi
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Min Sub Lee
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Wei Yuan Hsieh
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Jonathan J Mkrtchyan
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - An-Chieh Feng
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Cuiwen He
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Autumn G York
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA.,Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA.,Howard Hughes Medical Institute, Yale University, New Haven, CT, USA
| | - Viet L Bui
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Eliza B Kronenberger
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Alessandra Ferrari
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Xu Xiao
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Allison E Daly
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Elizabeth J Tarling
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Robert Damoiseaux
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Philip O Scumpia
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA.,Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Stephen T Smale
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA
| | - Kevin J Williams
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA, USA.,Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Steven J Bensinger
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, CA, USA. .,Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, USA.
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Pleckaityte M. Cholesterol-Dependent Cytolysins Produced by Vaginal Bacteria: Certainties and Controversies. Front Cell Infect Microbiol 2020; 9:452. [PMID: 31998661 PMCID: PMC6966277 DOI: 10.3389/fcimb.2019.00452] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 12/12/2019] [Indexed: 01/16/2023] Open
Abstract
Bacterial vaginosis (BV) is a vaginal anaerobic dysbiosis that affects women of reproductive age worldwide. BV is microbiologically characterized by the depletion of vaginal lactobacilli and the overgrowth of anaerobic bacterial species. Accumulated evidence suggests that Gardnerella spp. have a pivotal role among BV-associated bacteria in the initiation and development of BV. However, Gardnerella spp. often colonize healthy women. Lactobacillus iners is considered as a prevalent constituent of healthy vaginal microbiota, and is abundant in BV. Gardnerella spp. and L. iners secrete the toxins vaginolysin (VLY) and inerolysin (INY), which have structural and activity features attributed to cholesterol-dependent cytolysins (CDCs). CDCs are produced by many pathogenic bacteria as virulence factors that participate in various stages of disease progression by forming lytic and non-lytic pores in cell membranes or via pore-independent pathways. VLY is expressed in the majority of Gardnerella spp. isolates; less is known about the prevalence of the gene that encodes INY. INY is a classical CDC; membrane cholesterol acts a receptor for INY. VLY uses human CD59 as its receptor, although cholesterol remains indispensable for VLY pore-forming activity. INY-induced damage of artificial membranes is directly dependent on cholesterol concentration in the bilayer, whereas VLY-induced damage occurs with high levels of membrane cholesterol (>40 mol%). VLY primarily forms membrane-embedded complete rings in the synthetic bilayer, whereas INY forms arciform structures with smaller pore sizes. VLY activity is high at elevated pH, which is characteristic of BV, whereas INY activity is high at more acidic pH, which is specific for a healthy vagina. Increased VLY levels in vaginal mucosa in vivo were associated with clinical indicators of BV. However, experimental evidence is lacking for the specific roles of VLY and INY in BV. The interplay between vaginal bacterial species affects the expression of the gene encoding VLY, thereby modulating the virulence of Gardnerella spp. This review discusses the current evidence for VLY and INY cytolysins, including their structures and activities, factors affecting their expression, and their potential impacts on the progression of anaerobic dysbiosis.
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Affiliation(s)
- Milda Pleckaityte
- Laboratory of Immunology and Cell Biology, Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
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29
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Naito T, Ercan B, Krshnan L, Triebl A, Koh DHZ, Wei FY, Tomizawa K, Torta FT, Wenk MR, Saheki Y. Movement of accessible plasma membrane cholesterol by the GRAMD1 lipid transfer protein complex. eLife 2019; 8:51401. [PMID: 31724953 PMCID: PMC6905856 DOI: 10.7554/elife.51401] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/13/2019] [Indexed: 12/18/2022] Open
Abstract
Cholesterol is a major structural component of the plasma membrane (PM). The majority of PM cholesterol forms complexes with other PM lipids, making it inaccessible for intracellular transport. Transition of PM cholesterol between accessible and inaccessible pools maintains cellular homeostasis, but how cells monitor the accessibility of PM cholesterol remains unclear. We show that endoplasmic reticulum (ER)-anchored lipid transfer proteins, the GRAMD1s, sense and transport accessible PM cholesterol to the ER. GRAMD1s bind to one another and populate ER-PM contacts by sensing a transient expansion of the accessible pool of PM cholesterol via their GRAM domains. They then facilitate the transport of this cholesterol via their StART-like domains. Cells that lack all three GRAMD1s exhibit striking expansion of the accessible pool of PM cholesterol as a result of less efficient PM to ER transport of accessible cholesterol. Thus, GRAMD1s facilitate the movement of accessible PM cholesterol to the ER in order to counteract an acute increase of PM cholesterol, thereby activating non-vesicular cholesterol transport. The human body contains trillions of cells. At the outer edge of each cell is the plasma membrane, which protects the cell from the external environment. This membrane is mostly made of fatty molecules known as lipids and about half of these lipids are specifically cholesterol. Human cells can either take up cholesterol that were obtained via the diet or produce it within a compartment of the cell called the endoplasmic reticulum. Cells need to monitor the cholesterol levels in both the endoplasmic reticulum and the plasma membrane in order to regulate the uptake or production of this lipid. For example, if there is too much of cholesterol in the plasma membrane, then the cell transports some to the endoplasmic reticulum to tell it to shut down cholesterol production. However, how these different areas of the cell communicate with each other, and transport cholesterol, has remained unclear. Naito et al. set out to look for key regulators of cholesterol transport and identified a group of endoplasmic reticulum proteins called GRAMD1 proteins. Cholesterol in the plasma membrane is either accessible or inaccessible, meaning it either can or cannot be moved back into the cell. The GRAMD1 proteins sense accessible cholesterol, and experiments with human cells grown in the laboratory showed that, specifically, the GRAMD1 proteins work together in a complex to sense accessible cholesterol at or near the plasma membrane. One particular part of the protein senses when the amount of accessible cholesterol reaches a certain level at the plasma membrane; when this threshold is reached, the complex flips a switch to start the transport of cholesterol to the endoplasmic reticulum and tell it to shut down cholesterol production. This coupling of sensing and transporting lipids by one protein complex also helps maintain the right ratio of accessible and inaccessible cholesterol in the plasma membrane to prevent cells from activating unwanted cell-signaling events. Getting rid of the GRAMD1 proteins in cells, or removing sensing part of these proteins, leads to inefficient transport of cholesterol. A better understanding of how GRAMD1 proteins sense the accessibility of cholesterol could potentially help identify new approaches to control cholesterol transport inside cells. This may in turn eventually lead to new treatments that counteract the defects in cholesterol metabolism seen in some forms of neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease.
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Affiliation(s)
- Tomoki Naito
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Bilge Ercan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Logesvaran Krshnan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Alexander Triebl
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Dylan Hong Zheng Koh
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Fan-Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Federico Tesio Torta
- Department of Biochemistry, 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
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.,Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Japan
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30
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Johnson KA, Endapally S, Vazquez DC, Infante RE, Radhakrishnan A. Ostreolysin A and anthrolysin O use different mechanisms to control movement of cholesterol from the plasma membrane to the endoplasmic reticulum. J Biol Chem 2019; 294:17289-17300. [PMID: 31597703 DOI: 10.1074/jbc.ra119.010393] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 10/08/2019] [Indexed: 01/30/2023] Open
Abstract
Recent studies using two cholesterol-binding bacterial toxin proteins, perfringolysin O (PFO) and domain 4 of anthrolysin O (ALOD4), have shown that cholesterol in the plasma membranes (PMs) of animal cells resides in three distinct pools. The first pool comprises mobile cholesterol, accessible to both PFO and ALOD4, that is rapidly transported to the endoplasmic reticulum (ER) to signal cholesterol excess and maintain cholesterol homeostasis. The second is a sphingomyelin (SM)-sequestered pool inaccessible to PFO and ALOD4 but that becomes accessible by treatment with SM-degrading sphingomyelinase (SMase). The third is an essential pool also inaccessible to PFO and ALOD4 that cannot be liberated by SMase treatment. The accessible cholesterol pool can be trapped on PMs of live cells by nonlytic ALOD4, blocking its transport to the ER. However, studies of the two other pools have been hampered by a lack of available tools. Here, we used ostreolysin A (OlyA), which specifically binds SM/cholesterol complexes in membranes, to study the SM-sequestered cholesterol pool. Binding of nonlytic OlyA to SM/cholesterol complexes in PMs of live cells depleted the accessible PM cholesterol pool detectable by ALOD4. Consequently, transport of accessible cholesterol from PM to ER ceased, thereby activating SREBP transcription factors and increasing cholesterol synthesis. Thus, OlyA and ALOD4 both control movement of PM cholesterol, but through different lipid-binding mechanisms. We also found that PM-bound OlyA was rapidly internalized into cells, whereas PM-bound ALOD4 remained on the cell surface. Our findings establish OlyA and ALOD4 as complementary tools to investigate cellular cholesterol transport.
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Affiliation(s)
- Kristen A Johnson
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Shreya Endapally
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Danya C Vazquez
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Rodney E Infante
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390 .,Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390.,Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, Texas 75390.,Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Arun Radhakrishnan
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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31
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Rodriguez-Agudo D, Malacrida L, Kakiyama G, Sparrer T, Fortes C, Maceyka M, Subler MA, Windle JJ, Gratton E, Pandak WM, Gil G. StarD5: an ER stress protein regulates plasma membrane and intracellular cholesterol homeostasis. J Lipid Res 2019; 60:1087-1098. [PMID: 31015253 PMCID: PMC6547630 DOI: 10.1194/jlr.m091967] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 04/08/2019] [Indexed: 01/01/2023] Open
Abstract
How plasma membrane (PM) cholesterol is controlled is poorly understood. Ablation of the gene encoding the ER stress steroidogenic acute regulatory-related lipid transfer domain (StarD)5 leads to a decrease in PM cholesterol content, a decrease in cholesterol efflux, and an increase in intracellular neutral lipid accumulation in macrophages, the major cell type that expresses StarD5. ER stress increases StarD5 expression in mouse hepatocytes, which results in an increase in accessible PM cholesterol in WT but not in StarD5-/- hepatocytes. StarD5-/- mice store higher levels of cholesterol and triglycerides, which leads to altered expression of cholesterol-regulated genes. In vitro, a recombinant GST-StarD5 protein transfers cholesterol between synthetic liposomes. StarD5 overexpression leads to a marked increase in PM cholesterol. Phasor analysis of 6-dodecanoyl-2-dimethylaminonaphthalene fluorescence lifetime imaging microscopy data revealed an increase in PM fluidity in StarD5-/- macrophages. Taken together, these studies show that StarD5 is a stress-responsive protein that regulates PM cholesterol and intracellular cholesterol homeostasis.
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Affiliation(s)
- Daniel Rodriguez-Agudo
- Departments of Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
- McGuire Veterans Affairs Medical Center, Richmond, VA 23248
| | - Leonel Malacrida
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California at Irvine, Irvine, CA 92697
- Area de Investigación Respiratoria, Departamento de Fisiopatologia, Hospital de Clinicas, Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay
| | - Genta Kakiyama
- Departments of Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
- McGuire Veterans Affairs Medical Center, Richmond, VA 23248
| | - Tavis Sparrer
- Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
| | - Carolina Fortes
- Departments of Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
- Departmento de Biologia Molecular y Bioquimica, Universidad de Malaga, Malaga, Spain
| | - Michael Maceyka
- Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
- Massey Cancer Center, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
| | - Mark A Subler
- Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
| | - Jolene J Windle
- Massey Cancer Center, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
- Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California at Irvine, Irvine, CA 92697
| | - William M Pandak
- Departments of Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
- McGuire Veterans Affairs Medical Center, Richmond, VA 23248
| | - Gregorio Gil
- Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
- Massey Cancer Center, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
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32
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Ayuyan AG, Cohen FS. The Chemical Potential of Plasma Membrane Cholesterol: Implications for Cell Biology. Biophys J 2019; 114:904-918. [PMID: 29490250 DOI: 10.1016/j.bpj.2017.12.042] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 12/21/2017] [Accepted: 12/28/2017] [Indexed: 10/17/2022] Open
Abstract
Cholesterol is abundant in plasma membranes and exhibits a variety of interactions throughout the membrane. Chemical potential accounts for thermodynamic consequences of molecular interactions, and quantifies the effective concentration (i.e., activity) of any substance participating in a process. We have developed, to our knowledge, the first method to measure cholesterol chemical potential in plasma membranes. This was accomplished by complexing methyl-β-cyclodextrin with cholesterol in an aqueous solution and equilibrating it with an organic solvent containing dissolved cholesterol. The chemical potential of cholesterol was thereby equalized in the two phases. Because cholesterol is dilute in the organic phase, here activity and concentration were equivalent. This equivalence allowed the amount of cholesterol bound to methyl-β-cyclodextrin to be converted to cholesterol chemical potential. Our method was used to determine the chemical potential of cholesterol in erythrocytes and in plasma membranes of nucleated cells in culture. For erythrocytes, the chemical potential did not vary when the concentration was below a critical value. Above this value, the chemical potential progressively increased with concentration. We used standard cancer lines to characterize cholesterol chemical potential in plasma membranes of nucleated cells. This chemical potential was significantly greater for highly metastatic breast cancer cells than for nonmetastatic breast cancer cells. Chemical potential depended on density of the cancer cells. A method to alter and fix the cholesterol chemical potential to any value (i.e., a cholesterol chemical potential clamp) was also developed. Cholesterol content did not change when cells were clamped for 24-48 h. It was found that the level of activation of the transcription factor STAT3 increased with increasing cholesterol chemical potential. The cholesterol chemical potential may regulate signaling pathways.
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Affiliation(s)
- Artem G Ayuyan
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, Illinois.
| | - Fredric S Cohen
- Department of Physiology and Biophysics, Rush University Medical Center, Chicago, Illinois.
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33
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Endapally S, Frias D, Grzemska M, Gay A, Tomchick DR, Radhakrishnan A. Molecular Discrimination between Two Conformations of Sphingomyelin in Plasma Membranes. Cell 2019; 176:1040-1053.e17. [PMID: 30712872 DOI: 10.1016/j.cell.2018.12.042] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 09/19/2018] [Accepted: 12/21/2018] [Indexed: 12/14/2022]
Abstract
Sphingomyelin and cholesterol are essential lipids that are enriched in plasma membranes of animal cells, where they interact to regulate membrane properties and many intracellular signaling processes. Despite intense study, the interaction between these lipids in membranes is not well understood. Here, structural and biochemical analyses of ostreolysin A (OlyA), a protein that binds to membranes only when they contain both sphingomyelin and cholesterol, reveal that sphingomyelin adopts two distinct conformations in membranes when cholesterol is present. One conformation, bound by OlyA, is induced by stoichiometric, exothermic interactions with cholesterol, properties that are consistent with sphingomyelin/cholesterol complexes. In its second conformation, sphingomyelin is free from cholesterol and does not bind OlyA. A point mutation abolishes OlyA's ability to discriminate between these two conformations. In cells, levels of sphingomyelin/cholesterol complexes are held constant over a wide range of plasma membrane cholesterol concentrations, enabling precise regulation of the chemical activity of cholesterol.
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Affiliation(s)
- Shreya Endapally
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Donna Frias
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Magdalena Grzemska
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Austin Gay
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Diana R Tomchick
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Arun Radhakrishnan
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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34
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Monitoring and Modulating Intracellular Cholesterol Trafficking Using ALOD4, a Cholesterol-Binding Protein. Methods Mol Biol 2019; 1949:153-163. [PMID: 30790255 DOI: 10.1007/978-1-4939-9136-5_12] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mammalian cells carefully control their cholesterol levels by employing multiple feedback mechanisms to regulate synthesis of cholesterol and uptake of cholesterol from circulating lipoproteins. Most of a cell's cholesterol (~80% of total) is in the plasma membrane (PM), but the protein machinery that regulates cellular cholesterol resides in the endoplasmic reticulum (ER) membrane, which contains a very small fraction (~1% of total) of a cell's cholesterol. How does the ER communicate with PM to monitor cholesterol levels in that membrane? Here, we describe a tool, ALOD4, that helps us answer this question. ALOD4 traps cholesterol at the PM, leading to depletion of ER cholesterol without altering total cell cholesterol. The effects of ALOD4 are reversible. This tool has been used to show that the ER is able to continuously sample cholesterol from PM, providing ER with information about levels of PM cholesterol.
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35
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Ray S, Thapa R, Keyel PA. Multiple Parameters Beyond Lipid Binding Affinity Drive Cytotoxicity of Cholesterol-Dependent Cytolysins. Toxins (Basel) 2018; 11:toxins11010001. [PMID: 30577571 PMCID: PMC6356533 DOI: 10.3390/toxins11010001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/14/2018] [Accepted: 12/18/2018] [Indexed: 02/06/2023] Open
Abstract
The largest superfamily of bacterial virulence factors is pore-forming toxins (PFTs). PFTs are secreted by both pathogenic and non-pathogenic bacteria. PFTs sometimes kill or induce pro-pathogen signaling in mammalian cells, all primarily through plasma membrane perforation, though the parameters that determine these outcomes are unclear. Membrane binding, calcium influx, pore size, and membrane repair are factors that influence PFT cytotoxicity. To test the contribution of membrane binding to cytotoxicity and repair, we compared the closely related, similarly-sized PFTs Perfringolysin O (PFO) from Clostridium perfringens and Streptolysin O (SLO) from Streptococcus pyogenes. Cell death kinetics for PFO and SLO were different because PFO increased in cytotoxicity over time. We introduced known L3 loop mutations that swap binding affinity between toxins and measured hemolytic activity, nucleated cell death kinetics and membrane repair using viability assays, and live cell imaging. Altered hemolytic activity was directly proportional to toxin binding affinity. In contrast, L3 loop alterations reduced nucleated cell death, and they had limited effects on cytotoxicity kinetics and membrane repair. This suggests other toxin structural features, like oligomerization, drives these parameters. Overall, these findings suggest that repair mechanisms and toxin oligomerization add constraints beyond membrane binding on toxin evolution and activity against nucleated cells.
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Affiliation(s)
- Sucharit Ray
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Box 43131, Lubbock, TX 79409, USA.
| | - Roshan Thapa
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Box 43131, Lubbock, TX 79409, USA.
| | - Peter A Keyel
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Box 43131, Lubbock, TX 79409, USA.
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36
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Steck TL, Lange Y. Transverse distribution of plasma membrane bilayer cholesterol: Picking sides. Traffic 2018; 19:750-760. [PMID: 29896788 DOI: 10.1111/tra.12586] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/04/2018] [Accepted: 06/05/2018] [Indexed: 12/23/2022]
Abstract
The transverse asymmetry (sidedness) of phospholipids in plasma membrane bilayers is well characterized, distinctive, actively maintained and functionally important. In contrast, numerous studies using a variety of techniques have concluded that plasma membrane bilayer cholesterol is either mostly in the outer leaflet or the inner leaflet or is fairly evenly distributed. Sterols might simply partition according to their differing affinities for the asymmetrically disposed phospholipids, but some studies have proposed that it is actively transported to the outer leaflet. Other work suggests that the sterol is enriched in the inner leaflet, driven by either positive interactions with the phosphatidylethanolamine on that side or by its exclusion from the outer leaflet by the long chain sphingomyelin molecules therein. This uncertainty raises three questions: is plasma membrane cholesterol sidedness fixed in a given cell or cell type; is it generally the same among mammalian species; and does it serve specific physiological functions? This review grapples with these issues.
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Affiliation(s)
- Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois
| | - Yvonne Lange
- Department of Pathology, Rush University Medical Center, Chicago, Illinois
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37
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Mechanisms of cellular cholesterol compartmentalization: recent insights. Curr Opin Cell Biol 2018; 53:77-83. [PMID: 29960186 DOI: 10.1016/j.ceb.2018.06.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 05/07/2018] [Accepted: 06/05/2018] [Indexed: 11/20/2022]
Abstract
This review discusses advances in understanding how the controlled delivery of cholesterol between subcellular compartments is achieved and what novel experimental strategies are being employed to address this fundamental question. Recent work has focused on cholesterol-binding proteins that can facilitate directional cholesterol transfer between contacts of the ER and Golgi or late endosomal membranes. Increasing structural information on cholesterol-binding proteins, new modules engineered from them as well as improved imaging and gene editing techniques are providing valuable insights. There is also mounting information on how the crosstalk between cholesterol transport and nutrient signaling is orchestrated and how cellular fatty acid metabolism and cholesterol homeostasis are intertwined.
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38
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Mechanistic Insights into the Cholesterol-dependent Binding of Perfringolysin O-based Probes and Cell Membranes. Sci Rep 2017; 7:13793. [PMID: 29061991 PMCID: PMC5653841 DOI: 10.1038/s41598-017-14002-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 10/05/2017] [Indexed: 11/18/2022] Open
Abstract
Cholesterol distribution in the cell is maintained by both vesicular and non-vesicular sterol transport. Non-vesicular transport is mediated by the interaction of membrane-embedded cholesterol and water-soluble proteins. Small changes to the lipid composition of the membrane that do not change the total cholesterol content, can significantly affect how cholesterol interacts with other molecules at the surface of the membrane. The cholesterol-dependent cytolysin Perfringolysin O (PFO) constitutes a powerful tool to detect cholesterol in membranes, and the use of PFO-based probes has flourished in recent years. By using a non-lytic PFO derivative, we showed that the sensitivity of the probes for cholesterol can be tuned by modifications introduced directly in the membrane-interacting loops and/or by modifying residues away from the membrane-interacting domain. Through the use of these biosensors on live RAW 264.7 cells, we found that changes in the overall cholesterol content have a limited effect on the average cholesterol accessibility at the surface of the membrane. We showed that these exquisite biosensors report on changes in cholesterol reactivity at the membrane surface independently of the overall cholesterol content in the membrane.
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39
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Pilling LC, Atkins JL, Duff MO, Beaumont RN, Jones SE, Tyrrell J, Kuo CL, Ruth KS, Tuke MA, Yaghootkar H, Wood AR, Murray A, Weedon MN, Harries LW, Kuchel GA, Ferrucci L, Frayling TM, Melzer D. Red blood cell distribution width: Genetic evidence for aging pathways in 116,666 volunteers. PLoS One 2017; 12:e0185083. [PMID: 28957414 PMCID: PMC5619771 DOI: 10.1371/journal.pone.0185083] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 09/06/2017] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Variability in red blood cell volumes (distribution width, RDW) increases with age and is strongly predictive of mortality, incident coronary heart disease and cancer. We investigated inherited genetic variation associated with RDW in 116,666 UK Biobank human volunteers. RESULTS A large proportion RDW is explained by genetic variants (29%), especially in the older group (60+ year olds, 33.8%, <50 year olds, 28.4%). RDW was associated with 194 independent genetic signals; 71 are known for conditions including autoimmune disease, certain cancers, BMI, Alzheimer's disease, longevity, age at menopause, bone density, myositis, Parkinson's disease, and age-related macular degeneration. Exclusion of anemic participants did not affect the overall findings. Pathways analysis showed enrichment for telomere maintenance, ribosomal RNA, and apoptosis. The majority of RDW-associated signals were intronic (119 of 194), including SNP rs6602909 located in an intron of oncogene GAS6, an eQTL in whole blood. CONCLUSIONS Although increased RDW is predictive of cardiovascular outcomes, this was not explained by known CVD or related lipid genetic risks, and a RDW genetic score was not predictive of incident disease. The predictive value of RDW for a range of negative health outcomes may in part be due to variants influencing fundamental pathways of aging.
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Affiliation(s)
- Luke C. Pilling
- Epidemiology and Public Health Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
- * E-mail:
| | - Janice L. Atkins
- Epidemiology and Public Health Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - Michael O. Duff
- Department of Genetics and Genome Sciences, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Robin N. Beaumont
- Genetics of Complex Traits Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - Samuel E. Jones
- Genetics of Complex Traits Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - Jessica Tyrrell
- Genetics of Complex Traits Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - Chia-Ling Kuo
- Department of Community Medicine and Health Care, Connecticut Institute for Clinical and Translational Science, Institute for Systems Genomics, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Katherine S. Ruth
- Genetics of Complex Traits Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - Marcus A. Tuke
- Genetics of Complex Traits Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - Hanieh Yaghootkar
- Genetics of Complex Traits Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - Andrew R. Wood
- Genetics of Complex Traits Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - Anna Murray
- Genetics of Complex Traits Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - Michael N. Weedon
- Genetics of Complex Traits Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - Lorna W. Harries
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, United Kingdom
| | - George A. Kuchel
- Center on Aging, University of Connecticut, Farmington, CT, United States of America
| | - Luigi Ferrucci
- National Institute on Aging, Baltimore, MD, United States
| | - Timothy M. Frayling
- Genetics of Complex Traits Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
| | - David Melzer
- Epidemiology and Public Health Group, University of Exeter Medical School, RILD Level 3, Royal Devon & Exeter Hospital, Exeter, EX2 5DW, United Kingdom
- Center on Aging, University of Connecticut, Farmington, CT, United States of America
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Sviridov D, Mukhamedova N. Cholesterol: a dark horse in signalling race. Curr Opin Lipidol 2017; 28:385-386. [PMID: 28700381 DOI: 10.1097/mol.0000000000000435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Dmitri Sviridov
- Baker Heart and Diabetes Institute, Melbourne, Victoria, Australia
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