1
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Hosamani S, Chakraborty S. Cholesterol Allosterically Modulates the Structure and Dynamics of the Taurocholate Export Pump (ABCB11). J Phys Chem Lett 2024; 15:7901-7908. [PMID: 39058973 DOI: 10.1021/acs.jpclett.4c01341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2024]
Abstract
The BSEP/ABCB11 transmembrane protein translocates taurine- and glycine-conjugated bile salts across the hepatocyte bilayer driven by ATP-hydrolysis. Direct inhibition of BSEP/ABCB11 leads to idiosyncratic drug-induced liver injury. ABCB11 is localized within the cholesterol-enriched lipid raft, and membrane cholesterol depletion leads to impaired taurocholate transport. However, structural insight into the mechanism of the cholesterol-mediated regulation of ABCB11 activity remains elusive. We used extensive molecular dynamics simulation coupled with well-tempered metadynamics to elucidate the role of membrane cholesterol in the structure and dynamics of ABCB11. We identified specific high-residence binding sites for cholesterol within the transmembrane domain. The free-energy simulations have elucidated that the bound cholesterol stabilizes the "inward-open" conformation of the protein. Cholesterol-ABCB11 interactions trigger allosteric communications between the transmembrane and nucleotide-binding domains through the linker region. Cholesterol depletion destabilizes the allosteric network of the protein. As a result, it adopts a more collapsed form with a reduced volume of the taurocholate-binding pocket.
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Affiliation(s)
- Soundharya Hosamani
- Center for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Gachibowli, Hyderabad 500046, India
| | - Sandipan Chakraborty
- Center for Innovation in Molecular and Pharmaceutical Sciences (CIMPS), Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Gachibowli, Hyderabad 500046, India
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2
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Chen Y, Fang H, Sun H, Wu X, Xu Y, Zhou BBS, Li H. Up-regulation of ABCG1 is associated with methotrexate resistance in acute lymphoblastic leukemia cells. Front Pharmacol 2024; 14:1331687. [PMID: 38259297 PMCID: PMC10800869 DOI: 10.3389/fphar.2023.1331687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 12/18/2023] [Indexed: 01/24/2024] Open
Abstract
Acute lymphoblastic leukemia (ALL) is a prevalent hematologic malignancy in children, and methotrexate (MTX) is a widely employed curative treatment. Despite its common use, clinical resistance to MTX is frequently encountered. In this study, an MTX-resistant cell line (Reh-MTXR) was established through a stepwise selection process from the ALL cell line Reh. Comparative analysis revealed that Reh-MTXR cells exhibited resistance to MTX in contrast to the parental Reh cells. RNA-seq analysis identified an upregulation of ATP-binding cassette transporter G1 (ABCG1) in Reh-MTXR cells. Knockdown of ABCG1 in Reh-MTXR cells reversed the MTX-resistant phenotype, while overexpression of ABCG1 in Reh cells conferred resistance to MTX. Mechanistically, the heightened expression of ABCG1 accelerated MTX efflux, leading to a reduced accumulation of MTX polyglutamated metabolites. Notably, the ABCG1 inhibitor benzamil effectively sensitized Reh-MTXR cells to MTX treatment. Moreover, the observed upregulation of ABCG1 in Reh-MTXR cells was not induced by alterations in DNA methylation or histone acetylation. This study provides insight into the mechanistic basis of MTX resistance in ALL and also suggests a potential therapeutic approach for MTX-resistant ALL in the future.
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Affiliation(s)
- Yao Chen
- Pediatric Translational Medicine Institute, Key Laboratory of Pediatric Hematology and Oncology Ministry of Health, Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Houshun Fang
- Pediatric Translational Medicine Institute, Key Laboratory of Pediatric Hematology and Oncology Ministry of Health, Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Huiying Sun
- Pediatric Translational Medicine Institute, Key Laboratory of Pediatric Hematology and Oncology Ministry of Health, Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiaoyu Wu
- Pediatric Translational Medicine Institute, Key Laboratory of Pediatric Hematology and Oncology Ministry of Health, Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan Xu
- Pediatric Translational Medicine Institute, Key Laboratory of Pediatric Hematology and Oncology Ministry of Health, Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Bin-Bing S. Zhou
- Pediatric Translational Medicine Institute, Key Laboratory of Pediatric Hematology and Oncology Ministry of Health, Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Fujian Children’s Hospital, Fujian Branch of Shanghai Children’s Medical Center Affiliated to Shanghai Jiaotong University School of Medicine, Fuzhou, China
- Department of Pharmacology and Chemical Biology, School of Basic Medicine and Shanghai Collaborative Innovation Center for Translational Medicine Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hui Li
- Pediatric Translational Medicine Institute, Key Laboratory of Pediatric Hematology and Oncology Ministry of Health, Shanghai Children’s Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Fujian Children’s Hospital, Fujian Branch of Shanghai Children’s Medical Center Affiliated to Shanghai Jiaotong University School of Medicine, Fuzhou, China
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3
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Huang X, Zhang X, An N, Zhang M, Ma M, Yang Y, Jing L, Wang Y, Chen Z, Zhang P. Cryo-EM structure and molecular mechanism of abscisic acid transporter ABCG25. NATURE PLANTS 2023; 9:1709-1719. [PMID: 37666961 DOI: 10.1038/s41477-023-01509-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 08/02/2023] [Indexed: 09/06/2023]
Abstract
Abscisic acid (ABA) is one of the plant hormones that regulate various physiological processes, including stomatal closure, seed germination and development. ABA is synthesized mainly in vascular tissues and transported to distal sites to exert its physiological functions. Many ABA transporters have been identified, however, the molecular mechanism of ABA transport remains elusive. Here we report the cryogenic electron microscopy structure of the Arabidopsis thaliana adenosine triphosphate-binding cassette G subfamily ABA exporter ABCG25 (AtABCG25) in inward-facing apo conformation, ABA-bound pre-translocation conformation and outward-facing occluded conformation. Structural and biochemical analyses reveal that the ABA bound with ABCG25 adopts a similar configuration as that in ABA receptors and that the ABA-specific binding is dictated by residues from transmembrane helices TM1, TM2 and TM5a of each protomer at the transmembrane domain interface. Comparison of different conformational structures reveals conformational changes, especially those of transmembrane helices and residues constituting the substrate translocation pathway during the cross-membrane transport process. Based on the structural data, a 'gate-flipper' translocation model of ABCG25-mediated ABA cross-membrane transport is proposed. Our structural data on AtABCG25 provide new clues to the physiological study of ABA and shed light on its potential applications in plants and agriculture.
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Affiliation(s)
- Xiaowei Huang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xue Zhang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Ning An
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Minhua Zhang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Miaolian Ma
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Yang Yang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Lianyan Jing
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Yongfei Wang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Zhenguo Chen
- The Fifth People's Hospital of Shanghai, Institutes of Biomedical Sciences, School of Basic Medical Sciences, Fudan University, Shanghai, China.
| | - Peng Zhang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
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4
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Ying W, Liao L, Wei H, Gao Y, Liu X, Sun L. Structural basis for abscisic acid efflux mediated by ABCG25 in Arabidopsis thaliana. NATURE PLANTS 2023; 9:1697-1708. [PMID: 37666962 PMCID: PMC10581904 DOI: 10.1038/s41477-023-01510-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 08/02/2023] [Indexed: 09/06/2023]
Abstract
Abscisic acid (ABA) is a phytohormone essential to the regulation of numerous aspects of plant growth and development. The cellular level of ABA is critical to its signalling and is determined by its rate of biosynthesis, catabolism and the rates of ABA transport. ABCG25 in Arabidopsis thaliana has been identified to be an ABA exporter and play roles in regulating stomatal closure and seed germination. However, its ABA transport mechanism remains unknown. Here we report the structures of ABCG25 under different states using cryo-electron microscopy single particle analysis: the apo state and ABA-bound state of the wild-type ABCG25 and the ATP-bound state of the ATPase catalytic mutant. ABCG25 forms a homodimer. ABA binds to a cone-shaped, cytosolic-facing cavity formed in the middle of the transmembrane domains. Key residues in ABA binding are identified and verified by a cell-based ABA transport assay. ATP binding leads to closing of the nucleotide-binding domains of opposing monomers and conformational transitions of the transmembrane domains. Together, these results provide insights into the substrate recognition and transport mechanisms of ABCG25 in Arabidopsis, and facilitate our understanding of the ABA transport and signalling pathway in plants.
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Affiliation(s)
- Wei Ying
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Lianghuan Liao
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Hong Wei
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yongxiang Gao
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Xin Liu
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, China.
| | - Linfeng Sun
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, China.
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5
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Gose T, Aitken HM, Wang Y, Lynch J, Rampersaud E, Fukuda Y, Wills M, Baril SA, Ford RC, Shelat A, Mara MLO, Schuetz JD. The net electrostatic potential and hydration of ABCG2 affect substrate transport. Nat Commun 2023; 14:5035. [PMID: 37596258 PMCID: PMC10439158 DOI: 10.1038/s41467-023-40610-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 08/03/2023] [Indexed: 08/20/2023] Open
Abstract
ABCG2 is a medically important ATP-binding cassette transporter with crucial roles in the absorption and distribution of chemically-diverse toxins and drugs, reducing the cellular accumulation of chemotherapeutic drugs to facilitate multidrug resistance in cancer. ABCG2's capacity to transport both hydrophilic and hydrophobic compounds is not well understood. Here we assess the molecular basis for substrate discrimination by the binding pocket. Substitution of a phylogenetically-conserved polar residue, N436, to alanine in the binding pocket of human ABCG2 permits only hydrophobic substrate transport, revealing the unique role of N436 as a discriminator. Molecular dynamics simulations show that this alanine substitution alters the electrostatic potential of the binding pocket favoring hydration of the transport pore. This change affects the contact with substrates and inhibitors, abrogating hydrophilic compound transport while retaining the transport of hydrophobic compounds. The N436 residue is also required for optimal transport inhibition of ABCG2, as many inhibitors are functionally impaired by this ABCG2 mutation. Overall, these findings have biomedical implications, broadly extending our understanding of substrate and inhibitor interactions.
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Affiliation(s)
- Tomoka Gose
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Heather M Aitken
- Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Australia, Cnr College Rd & Cooper Rd, St Lucia, QLD, 4072, Australia
| | - Yao Wang
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - John Lynch
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Evadnie Rampersaud
- Center for Applied Bioinformatics, St Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Yu Fukuda
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Medb Wills
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Stefanie A Baril
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Robert C Ford
- School of Biological Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Anang Shelat
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA
| | - Megan L O' Mara
- Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Australia, Cnr College Rd & Cooper Rd, St Lucia, QLD, 4072, Australia
| | - John D Schuetz
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105, USA.
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6
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Sacher S, Mukherjee A, Ray A. Deciphering structural aspects of reverse cholesterol transport: mapping the knowns and unknowns. Biol Rev Camb Philos Soc 2023; 98:1160-1183. [PMID: 36880422 DOI: 10.1111/brv.12948] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 02/03/2023] [Accepted: 02/24/2023] [Indexed: 03/08/2023]
Abstract
Atherosclerosis is a major contributor to the onset and progression of cardiovascular disease (CVD). Cholesterol-loaded foam cells play a pivotal role in forming atherosclerotic plaques. Induction of cholesterol efflux from these cells may be a promising approach in treating CVD. The reverse cholesterol transport (RCT) pathway delivers cholesteryl ester (CE) packaged in high-density lipoproteins (HDL) from non-hepatic cells to the liver, thereby minimising cholesterol load of peripheral cells. RCT takes place via a well-organised interplay amongst apolipoprotein A1 (ApoA1), lecithin cholesterol acyltransferase (LCAT), ATP binding cassette transporter A1 (ABCA1), scavenger receptor-B1 (SR-B1), and the amount of free cholesterol. Unfortunately, modulation of RCT for treating atherosclerosis has failed in clinical trials owing to our lack of understanding of the relationship between HDL function and RCT. The fate of non-hepatic CEs in HDL is dependent on their access to proteins involved in remodelling and can be regulated at the structural level. An inadequate understanding of this inhibits the design of rational strategies for therapeutic interventions. Herein we extensively review the structure-function relationships that are essential for RCT. We also focus on genetic mutations that disturb the structural stability of proteins involved in RCT, rendering them partially or completely non-functional. Further studies are necessary for understanding the structural aspects of RCT pathway completely, and this review highlights alternative theories and unanswered questions.
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Affiliation(s)
- Sukriti Sacher
- Department of Computational Biology, Indraprastha Institute of Information Technology, Okhla Phase III, New Delhi, 110019, India
| | - Abhishek Mukherjee
- Dhiti Life Sciences Pvt Ltd, B-107, Okhla Phase I, New Delhi, 110020, India
| | - Arjun Ray
- Department of Computational Biology, Indraprastha Institute of Information Technology, Okhla Phase III, New Delhi, 110019, India
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7
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Steck TL, Lange Y. Is reverse cholesterol transport regulated by active cholesterol? J Lipid Res 2023; 64:100385. [PMID: 37169287 PMCID: PMC10279919 DOI: 10.1016/j.jlr.2023.100385] [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: 04/02/2023] [Revised: 05/02/2023] [Accepted: 05/05/2023] [Indexed: 05/13/2023] Open
Abstract
This review considers the hypothesis that a small portion of plasma membrane cholesterol regulates reverse cholesterol transport in coordination with overall cellular homeostasis. It appears that almost all of the plasma membrane cholesterol is held in stoichiometric complexes with bilayer phospholipids. The minor fraction of cholesterol that exceeds the complexation capacity of the phospholipids is called active cholesterol. It has an elevated chemical activity and circulates among the organelles. It also moves down its chemical activity gradient to plasma HDL, facilitated by the activity of ABCA1, ABCG1, and SR-BI. ABCA1 initiates this process by perturbing the organization of the plasma membrane bilayer, thereby priming its phospholipids for translocation to apoA-I to form nascent HDL. The active excess sterol and that activated by ABCA1 itself follow the phospholipids to the nascent HDL. ABCG1 similarly rearranges the bilayer and sends additional active cholesterol to nascent HDL, while SR-BI simply facilitates the equilibration of the active sterol between plasma membranes and plasma proteins. Active cholesterol also flows downhill to cytoplasmic membranes where it serves both as a feedback signal to homeostatic ER proteins and as the substrate for the synthesis of mitochondrial 27-hydroxycholesterol (27HC). 27HC binds the LXR and promotes the expression of the aforementioned transport proteins. 27HC-LXR also activates ABCA1 by competitively displacing its inhibitor, unliganded LXR. § Considerable indirect evidence suggests that active cholesterol serves as both a substrate and a feedback signal for reverse cholesterol transport. Direct tests of this novel hypothesis are proposed.
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Affiliation(s)
- Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Yvonne Lange
- Department of Pathology, Rush University Medical Center, Chicago, IL, USA.
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8
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Abstract
ABC transporters are essential for cellular physiology. Humans have 48 ABC genes organized into seven distinct families. Of these genes, 44 (in five distinct families) encode for membrane transporters, of which several are involved in drug resistance and disease pathways resulting from transporter dysfunction. Over the last decade, advances in structural biology have vastly expanded our mechanistic understanding of human ABC transporter function, revealing details of their molecular arrangement, regulation, and interactions, facilitated in large part by advances in cryo-EM that have rendered hitherto inaccessible targets amenable to high-resolution structural analysis. As a result, experimentally determined structures of multiple members of each of the five families of ABC transporters in humans are now available. Here we review this recent progress, highlighting the physiological relevance of human ABC transporters and mechanistic insights gleaned from their direct structure determination. We also discuss the impact and limitations of model systems and structure prediction methods in understanding human ABC transporters and discuss current challenges and future research directions.
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Affiliation(s)
- Amer Alam
- The Hormel Institute, University of Minnesota, Austin, Minnesota, USA
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, ETH Zurich, Switzerland;
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9
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Pakuła K, Sequeiros-Borja C, Biała-Leonhard W, Pawela A, Banasiak J, Bailly A, Radom M, Geisler M, Brezovsky J, Jasiński M. Restriction of access to the central cavity is a major contributor to substrate selectivity in plant ABCG transporters. Cell Mol Life Sci 2023; 80:105. [PMID: 36952129 PMCID: PMC10036432 DOI: 10.1007/s00018-023-04751-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 02/22/2023] [Accepted: 03/06/2023] [Indexed: 03/24/2023]
Abstract
ABCG46 of the legume Medicago truncatula is an ABC-type transporter responsible for highly selective translocation of the phenylpropanoids, 4-coumarate, and liquiritigenin, over the plasma membrane. To investigate molecular determinants of the observed substrate selectivity, we applied a combination of phylogenetic and biochemical analyses, AlphaFold2 structure prediction, molecular dynamics simulations, and mutagenesis. We discovered an unusually narrow transient access path to the central cavity of MtABCG46 that constitutes an initial filter responsible for the selective translocation of phenylpropanoids through a lipid bilayer. Furthermore, we identified remote residue F562 as pivotal for maintaining the stability of this filter. The determination of individual amino acids that impact the selective transport of specialized metabolites may provide new opportunities associated with ABCGs being of interest, in many biological scenarios.
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Affiliation(s)
- Konrad Pakuła
- Department of Plant Molecular Physiology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704, Poznan, Poland
- NanoBioMedical Centre, Adam Mickiewicz University, Wszechnicy Piastowskiej 3, 61-614, Poznan, Poland
| | - Carlos Sequeiros-Borja
- Laboratory of Biomolecular Interactions and Transport, Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznanskiego 6, 61-614, Poznan, Poland
- International Institute of Molecular and Cell Biology in Warsaw, Ks. Trojdena 4, 02-109, Warsaw, Poland
| | - Wanda Biała-Leonhard
- Department of Plant Molecular Physiology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Aleksandra Pawela
- Department of Plant Molecular Physiology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Joanna Banasiak
- Department of Plant Molecular Physiology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704, Poznan, Poland
| | - Aurélien Bailly
- Department of Plant and Microbial Biology, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland
| | - Marcin Radom
- Department of Structural Bioinformatics, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z.Noskowskiego12/14, 61-704, Poznan, Poland
- Institute of Computing Science, Poznan University of Technology, Piotrowo 2, 60-965, Poznan, Poland
| | - Markus Geisler
- Department of Biology, University of Fribourg, Chem. du Musée 10, 1700, Fribourg, Switzerland
| | - Jan Brezovsky
- Laboratory of Biomolecular Interactions and Transport, Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznanskiego 6, 61-614, Poznan, Poland.
- International Institute of Molecular and Cell Biology in Warsaw, Ks. Trojdena 4, 02-109, Warsaw, Poland.
| | - Michał Jasiński
- Department of Plant Molecular Physiology, Institute of Bioorganic Chemistry, Polish Academy of Sciences, Z. Noskowskiego 12/14, 61-704, Poznan, Poland.
- Department of Biochemistry and Biotechnology, Poznan University of Life Sciences, Dojazd 11, 60-632, Poznan, Poland.
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10
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Yang TM, Miao M, Yu WQ, Wang X, Xia FJ, Li YJ, Guo SD. Targeting macrophages in atherosclerosis using nanocarriers loaded with liver X receptor agonists: A narrow review. Front Mol Biosci 2023; 10:1147699. [PMID: 36936982 PMCID: PMC10018149 DOI: 10.3389/fmolb.2023.1147699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 02/20/2023] [Indexed: 03/06/2023] Open
Abstract
Macrophages are involved in the whole process of atherosclerosis, which is characterized by accumulation of lipid and inflammation. Presently, clinically used lipid-lowering drugs cannot completely retard the progress of atherosclerosis. Liver X receptor (LXR) plays a key role in regulation of lipid metabolism and inflammation. Accumulating evidence have demonstrated that synthetic LXR agonists can significantly retard the development of atherosclerosis. However, these agonists induce sever hypertriglyceridemia and liver steatosis. These side effects have greatly limited their potential application for therapy of atherosclerosis. The rapid development of drug delivery system makes it possible to delivery interested drugs to special organs or cells using nanocarriers. Macrophages express various receptors which can recognize and ingest specially modified nanocarriers loaded with LXR agonists. In the past decades, a great progress has been made in this field. These macrophage-targeted nanocarriers loaded with LXR agonists are found to decrease atherosclerosis by reducing cholesterol accumulation and inflammatory reactions. Of important, these nanocarriers can alleviate side effects of LXR agonists. In this article, we briefly review the roles of macrophages in atherosclerosis, mechanisms of action of LXR agonists, and focus on the advances of macrophage-targeted nanocarriers loaded with LXR agonists. This work may promote the potential clinical application of these nanocarriers.
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Affiliation(s)
| | | | | | | | | | - Yan-Jie Li
- *Correspondence: Yan-Jie Li, ; Shou-Dong Guo,
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11
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Rezaei F, Farhat D, Gursu G, Samnani S, Lee JY. Snapshots of ABCG1 and ABCG5/G8: A Sterol's Journey to Cross the Cellular Membranes. Int J Mol Sci 2022; 24:ijms24010484. [PMID: 36613930 PMCID: PMC9820320 DOI: 10.3390/ijms24010484] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/20/2022] [Accepted: 12/22/2022] [Indexed: 12/29/2022] Open
Abstract
The subfamily-G ATP-binding cassette (ABCG) transporters play important roles in regulating cholesterol homeostasis. Recent progress in the structural data of ABCG1 and ABCG5/G8 disclose putative sterol binding sites that suggest the possible cholesterol translocation pathway. ABCG1 and ABCG5/G8 share high similarity in the overall molecular architecture, and both transporters appear to use several unique structural motifs to facilitate cholesterol transport along this pathway, including the phenylalanine highway and the hydrophobic valve. Interestingly, ABCG5/G8 is known to transport cholesterol and phytosterols, whereas ABCG1 seems to exclusively transport cholesterol. Ligand docking analysis indeed suggests a difference in recruiting sterol molecules to the known sterol-binding sites. Here, we further discuss how the different and shared structural features are relevant to their physiological functions, and finally provide our perspective on future studies in ABCG cholesterol transporters.
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Affiliation(s)
- Fatemeh Rezaei
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Danny Farhat
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Gonca Gursu
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Biochemistry Program, Faculty of Science, University of Ottawa, Ottawa, ON K1H 6N5, Canada
| | - Sabrina Samnani
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Biochemistry Program, Faculty of Science, University of Ottawa, Ottawa, ON K1H 6N5, Canada
| | - Jyh-Yeuan Lee
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Correspondence:
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12
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Thymic involution caused by repeated cocaine administration includes apoptotic cell loss followed by ectopic adipogenesis. PLoS One 2022; 17:e0277032. [PMID: 36441681 PMCID: PMC9704633 DOI: 10.1371/journal.pone.0277032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 10/19/2022] [Indexed: 11/29/2022] Open
Abstract
Cocaine abuse has a negative impact on the immune system. To investigate the adverse effects of binge cocaine administration on lymphoid organs such as thymus and spleen, we examined the effects of repeated intravenous (i.v.) administration of cocaine on rats. Sprague Dawley rats (male, 8 weeks old) received 20 mg/kg body weight of cocaine hydrochloride per day for 7 or 14 days. In addition to a significant loss in the weight of the spleen, consistent with our previous intraperitoneal (i.p.) injection model of binge cocaine abuse (50 mg/kg cocaine for 7 days), we also found a significant loss of weight as well as apparent shrinkage of the thymus in the cocaine group. Transcriptome analysis of the thymus revealed increased expressions of genes involved in apoptosis, such as Ifi27 and Traf2, as well as decreased expressions of several genes related to lipid metabolism, such as Cd36, Adipoq, Scd1, and Fabp4, in the thymus of the cocaine group (7 days), suggesting an apoptotic loss of thymic cells as well as alterations in lipid metabolism. Paradoxically, cocaine activates PPARγ, a key transcriptional factor activating lipid metabolism, although ectopic adipogenesis was scarcely observed in the thymus. Further analysis of rats administered 20 mg/kg cocaine for 14 days revealed ectopic adipogenesis, which was accompanied with the activation of PPARγ as well as increased expression of Adipoq and Fabp4, in the thymus. Taken together, these results indicate that repeated cocaine administration induces thymic involution, which is initiated by the loss of thymic cells through apoptosis and subsequent ectopic adipocyte development.
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13
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Hegyi Z, Hegedűs T, Homolya L. The Reentry Helix Is Potentially Involved in Cholesterol Sensing of the ABCG1 Transporter Protein. Int J Mol Sci 2022; 23:ijms232213744. [PMID: 36430223 PMCID: PMC9698493 DOI: 10.3390/ijms232213744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/28/2022] [Accepted: 11/05/2022] [Indexed: 11/10/2022] Open
Abstract
ABCG1 has been proposed to play a role in HDL-dependent cellular sterol regulation; however, details of the interaction between the transporter and its potential sterol substrates have not been revealed. In the present work, we explored the effect of numerous sterol compounds on the two isoforms of ABCG1 and ABCG4 and made efforts to identify the molecular motifs in ABCG1 that are involved in the interaction with cholesterol. The functional readouts used include ABCG1-mediated ATPase activity and ABCG1-induced apoptosis. We found that both ABCG1 isoforms and ABCG4 interact with several sterol compounds; however, they have selective sensitivities to sterols. Mutational analysis of potential cholesterol-interacting motifs in ABCG1 revealed altered ABCG1 functions when F571, L626, or Y586 were mutated. L430A and Y660A substitutions had no functional consequence, whereas Y655A completely abolished the ABCG1-mediated functions. Detailed structural analysis of ABCG1 demonstrated that the mutations modulating ABCG1 functions are positioned either in the so-called reentry helix (G-loop/TM5b,c) (Y586) or in its close proximity (F571 and L626). Cholesterol molecules resolved in the structure of ABCG1 are also located close to Y586. Based on the experimental observations and structural considerations, we propose an essential role for the reentry helix in cholesterol sensing in ABCG1.
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Affiliation(s)
- Zoltán Hegyi
- Institute of Enzymology, Research Centre for Natural Sciences, H-1117 Budapest, Hungary
| | - Tamás Hegedűs
- Department of Biophysics and Radiation Biology, Semmelweis University, H-1094 Budapest, Hungary
- ELKH-SE Biophysical Virology Research Group, Eötvös Loránd Research Network, H-1094 Budapest, Hungary
| | - László Homolya
- Institute of Enzymology, Research Centre for Natural Sciences, H-1117 Budapest, Hungary
- Correspondence: ; Tel.: +36-1-3826608
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14
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Kotlyarov S, Kotlyarova A. The Importance of the Plasma Membrane in Atherogenesis. MEMBRANES 2022; 12:1036. [PMID: 36363591 PMCID: PMC9698587 DOI: 10.3390/membranes12111036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/20/2022] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
Atherosclerotic cardiovascular diseases are an important medical problem due to their high prevalence, impact on quality of life and prognosis. The pathogenesis of atherosclerosis is an urgent medical and social problem, the solution of which may improve the quality of diagnosis and treatment of patients. Atherosclerosis is a complex chain of events, which proceeds over many years and in which many cells in the bloodstream and the vascular wall are involved. A growing body of evidence suggests that there are complex, closely linked molecular mechanisms that occur in the plasma membranes of cells involved in atherogenesis. Lipid transport, innate immune system receptor function, and hemodynamic regulation are linked to plasma membranes and their biophysical properties. A better understanding of these interrelationships will improve diagnostic quality and treatment efficacy.
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Affiliation(s)
- Stanislav Kotlyarov
- Department of Nursing, Ryazan State Medical University, 390026 Ryazan, Russia
| | - Anna Kotlyarova
- Department of Pharmacy Management and Economics, Ryazan State Medical University, 390026 Ryazan, Russia
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15
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Hou W, Xu D, Wang L, Chen Y, Chen Z, Zhou C, Chen Y. Plastic structures for diverse substrates: A revisit of human
ABC
transporters. Proteins 2022; 90:1749-1765. [DOI: 10.1002/prot.26406] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 07/31/2022] [Accepted: 08/01/2022] [Indexed: 12/18/2022]
Affiliation(s)
- Wen‐Tao Hou
- School of Life Sciences University of Science and Technology of China Hefei People's Republic of China
| | - Da Xu
- School of Life Sciences University of Science and Technology of China Hefei People's Republic of China
| | - Liang Wang
- School of Life Sciences University of Science and Technology of China Hefei People's Republic of China
| | - Yu Chen
- School of Life Sciences University of Science and Technology of China Hefei People's Republic of China
| | - Zhi‐Peng Chen
- School of Life Sciences University of Science and Technology of China Hefei People's Republic of China
| | - Cong‐Zhao Zhou
- School of Life Sciences University of Science and Technology of China Hefei People's Republic of China
| | - Yuxing Chen
- School of Life Sciences University of Science and Technology of China Hefei People's Republic of China
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16
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Ekiert DC, Coudray N, Bhabha G. Structure and mechanism of the bacterial lipid ABC transporter, MlaFEDB. Curr Opin Struct Biol 2022; 76:102429. [PMID: 35981415 PMCID: PMC9509461 DOI: 10.1016/j.sbi.2022.102429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 05/30/2022] [Accepted: 06/16/2022] [Indexed: 11/29/2022]
Abstract
The cell envelope of Gram-negative bacteria is composed of an inner membrane, outer membane, and an intervening periplasmic space. How the outer membrane lipids are trafficked and assembled there, and how the asymmetry of the outer membrane is maintained is an area of intense research. The Mla system has been implicated in the maintenance of lipid asymmetry in the outer membrane, and is generally thought to drive the removal of mislocalized phospholipids from the outer membrane and their retrograde transport to the inner membrane. At the heart of the Mla pathway is a structurally unique ABC transporter complex in the inner membrane, called MlaFEDB. Recently, an explosion of cryo-EM studies has begun to shed light on the structure and lipid translocation mechanism of MlaFEDB, with many parallels to other ABC transporter families, including human ABCA and ABCG, as well as bacterial lipopolysaccharide and O-antigen transporters. Here we synthesize information from all available structures, and propose a model for lipid trafficking across the cell envelope by MlaFEDB.
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Affiliation(s)
- Damian C Ekiert
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA; Department of Microbiology, New York University School of Medicine, New York, NY, USA.
| | - Nicolas Coudray
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Gira Bhabha
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
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17
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Farhat D, Rezaei F, Ristovski M, Yang Y, Stancescu A, Dzimkova L, Samnani S, Couture JF, Lee JY. Structural analysis of cholesterol binding and sterol selectivity by ABCG5/G8. J Mol Biol 2022; 434:167795. [PMID: 35988751 DOI: 10.1016/j.jmb.2022.167795] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 07/30/2022] [Accepted: 08/15/2022] [Indexed: 01/08/2023]
Abstract
The ATP-binding cassette (ABC) sterol transporters are responsible for maintaining cholesterol homeostasis in mammals by participating in reverse cholesterol transport (RCT) or transintestinal cholesterol efflux (TICE). The heterodimeric ABCG5/G8 carries out selective sterol excretion, preventing the abnormal accumulation of plant sterols in human bodies, while homodimeric ABCG1 contributes to the biogenesis and metabolism of high-density lipoproteins. A sterol-binding site on ABCG5/G8 was proposed at the interface of the transmembrane domain and the core of lipid bilayers. In this study, we have determined the crystal structure of ABCG5/G8 in a cholesterol-bound state. The structure combined with amino acid sequence analysis shows that in the proximity of the sterol-binding site, a highly conserved phenylalanine array supports functional implications for ABCG cholesterol/sterol transporters. Lastly, in silico docking analysis of cholesterol and stigmasterol (a plant sterol) suggests sterol-binding selectivity on ABCG5/G8, but not ABCG1. Together, our results provide a structural basis for cholesterol binding on ABCG5/G8 and the sterol selectivity by ABCG transporters.
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Affiliation(s)
- Danny Farhat
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Fatemeh Rezaei
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Milica Ristovski
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Translational and Molecular Medicine Program, Faculty of Medicine, University of Ottawa, Ontario, Ottawa, Canada
| | - Yidai Yang
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Albert Stancescu
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Biochemistry Program, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Lucia Dzimkova
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Biochemistry Program, Faculty of Science, University of Ottawa, Ottawa, Ontario, Canada
| | - Sabrina Samnani
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Biochemistry Program, Faculty of Science, University of Ottawa, Ottawa, Ontario, Canada
| | - Jean-François Couture
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Jyh-Yeuan Lee
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.
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18
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Juhl AD, Wüstner D. Pathways and Mechanisms of Cellular Cholesterol Efflux-Insight From Imaging. Front Cell Dev Biol 2022; 10:834408. [PMID: 35300409 PMCID: PMC8920967 DOI: 10.3389/fcell.2022.834408] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/04/2022] [Indexed: 12/24/2022] Open
Abstract
Cholesterol is an essential molecule in cellular membranes, but too much cholesterol can be toxic. Therefore, mammalian cells have developed complex mechanisms to remove excess cholesterol. In this review article, we discuss what is known about such efflux pathways including a discussion of reverse cholesterol transport and formation of high-density lipoprotein, the function of ABC transporters and other sterol efflux proteins, and we highlight their role in human diseases. Attention is paid to the biophysical principles governing efflux of sterols from cells. We also discuss recent evidence for cholesterol efflux by the release of exosomes, microvesicles, and migrasomes. The role of the endo-lysosomal network, lipophagy, and selected lysosomal transporters, such as Niemann Pick type C proteins in cholesterol export from cells is elucidated. Since oxysterols are important regulators of cellular cholesterol efflux, their formation, trafficking, and secretion are described briefly. In addition to discussing results obtained with traditional biochemical methods, focus is on studies that use established and novel bioimaging approaches to obtain insight into cholesterol efflux pathways, including fluorescence and electron microscopy, atomic force microscopy, X-ray tomography as well as mass spectrometry imaging.
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Affiliation(s)
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, PhyLife, Physical Life Sciences, University of Southern Denmark, Odense, Denmark
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19
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Structure and transport mechanism of the human cholesterol transporter ABCG1. Cell Rep 2022; 38:110298. [PMID: 35081353 DOI: 10.1016/j.celrep.2022.110298] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 12/13/2021] [Accepted: 01/04/2022] [Indexed: 12/31/2022] Open
Abstract
The reverse cholesterol transport pathway is responsible for the maintenance of human cholesterol homeostasis, an imbalance of which usually leads to atherosclerosis. As a key component of this pathway, the ATP-binding cassette transporter ABCG1 forwards cellular cholesterol to the extracellular acceptor nascent high-density lipoprotein (HDL). Here, we report a 3.26-Å cryo-electron microscopy structure of cholesterol-bound ABCG1 in an inward-facing conformation, which represents a turnover condition upon ATP binding. Structural analyses combined with functional assays reveals that a cluster of conserved hydrophobic residues, in addition to two sphingomyelins, constitute a well-defined cholesterol-binding cavity. The exit of this cavity is closed by three pairs of conserved Phe residues, which constitute a hydrophobic path for the release of cholesterol in an acceptor concentration-dependent manner. Overall, we propose an ABCG1-driven cholesterol transport cycle initiated by sphingomyelin-assisted cholesterol recruitment and accomplished by the release of cholesterol to HDL.
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