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Rana R, Pundir S, Lal UR, Chauhan R, Upadhyay SK, Kumar D. Phytochemistry and biological activity of Erigeron annuus (L.) Pers. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2023; 396:2331-2346. [PMID: 37178275 DOI: 10.1007/s00210-023-02518-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 04/29/2023] [Indexed: 05/15/2023]
Abstract
Erigeron annuus L. is a flowering herb of North America, Europe, Asia and Russia. This plant is used as folk medicine in China for the cure of indigestion, enteritis, epidemic hepatitis, haematuria and diabetes. Phytochemical studies showed the presence of 170 bioactive compounds like coumarins, flavonoids, terpenoids, polyacetylenic compounds; γ-pyrone derivatives, sterols and various caffeoylquinic acids derived from the essential oil and organic extracts from its various parts such as aerial parts, roots, leaves, stems and flowers. The pharmacological studies demonstrated various extracts and the compounds of E. annuus to exhibit anti-fungal, anti-atherosclerosis, anti-inflammatory, antidiabetic, phytotoxic, cytoprotective, antiobesity and antioxidant activities. This article covers a critical compendious on geographical distribution, botanical description, phytochemistry, ethnomedicinal uses and pharmacological activities of E. annuus. However, further in-depth studies are needed to determine the medical uses of E. annuus and its chemical constituents, pharmacological activities and clinical applications.
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Affiliation(s)
- Rupali Rana
- Department of Pharmaceutical Sciences, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | - Swati Pundir
- School of Pharmaceutical Sciences, Shoolini University, Himachal Pradesh, Solan, 173229, India.
| | - Uma Ranjan Lal
- School of Pharmaceutical Sciences, Shoolini University, Himachal Pradesh, Solan, 173229, India
- Department of Natural Products, National Institute of Pharmaceutical Education and Research, Punjab, 160062, Mohali, India
| | - Raveen Chauhan
- School of Pharmaceutical Sciences, Shoolini University, Himachal Pradesh, Solan, 173229, India
| | | | - Deepak Kumar
- Department of Pharmaceutical Chemistry, School of Pharmaceutical Sciences, Shoolini University, Himachal Pradesh, Solan, 173229, India.
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Pierce MR, Hougland JL. A rising tide lifts all MBOATs: recent progress in structural and functional understanding of membrane bound O-acyltransferases. Front Physiol 2023; 14:1167873. [PMID: 37250116 PMCID: PMC10213974 DOI: 10.3389/fphys.2023.1167873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 04/19/2023] [Indexed: 05/31/2023] Open
Abstract
Acylation modifications play a central role in biological and physiological processes. Across a range of biomolecules from phospholipids to triglycerides to proteins, introduction of a hydrophobic acyl chain can dramatically alter the biological function and cellular localization of these substrates. Amongst the enzymes catalyzing these modifications, the membrane bound O-acyltransferase (MBOAT) family occupies an intriguing position as the combined substrate selectivities of the various family members span all three classes of these biomolecules. MBOAT-dependent substrates are linked to a wide range of health conditions including metabolic disease, cancer, and neurodegenerative disease. Like many integral membrane proteins, these enzymes have presented challenges to investigation due to their intractability to solubilization and purification. However, over the last several years new solubilization approaches coupled with computational modeling, crystallography, and cryoelectron microscopy have brought an explosion of structural information for multiple MBOAT family members. These studies enable comparison of MBOAT structure and function across members catalyzing modifications of all three substrate classes, revealing both conserved features amongst all MBOATs and distinct architectural features that correlate with different acylation substrates ranging from lipids to proteins. We discuss the methods that led to this renaissance of MBOAT structural investigations, our new understanding of MBOAT structure and implications for catalytic function, and the potential impact of these studies for development of new therapeutics targeting MBOAT-dependent physiological processes.
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Affiliation(s)
- Mariah R. Pierce
- Department of Chemistry, Syracuse University, Syracuse, NY, United States
| | - James L. Hougland
- Department of Chemistry, Syracuse University, Syracuse, NY, United States
- Department of Biology, Syracuse University, Syracuse, NY, United States
- BioInspired Syracuse, Syracuse University, Syracuse, NY, United States
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3
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Bhattacharjee P, Rutland N, Iyer MR. Targeting Sterol O-Acyltransferase/Acyl-CoA:Cholesterol Acyltransferase (ACAT): A Perspective on Small-Molecule Inhibitors and Their Therapeutic Potential. J Med Chem 2022; 65:16062-16098. [PMID: 36473091 DOI: 10.1021/acs.jmedchem.2c01265] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sterol O-acyltransferase (SOAT) is a membrane-bound enzyme that aids the esterification of cholesterol and fatty acids to cholesterol esters. SOAT has been studied extensively as a potential drug target, since its inhibition can serve as an alternative to statin therapy. Two SOAT isozymes that have discrete functions in the human body, namely, SOAT1 and SOAT2, have been characterized. Over three decades of research has focused on candidate SOAT1 inhibitors with unsatisfactory results in clinical trials. Recent research has focused on targeting SOAT2 selectively. In this perspective, we summarize the literature covering various SOAT inhibitory agents and discuss the design, structural requirements, and mode of action of SOAT inhibitors.
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Affiliation(s)
- Pinaki Bhattacharjee
- Section on Medicinal Chemistry, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rockville, Maryland 20852, United States
| | - Nicholas Rutland
- Section on Medicinal Chemistry, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rockville, Maryland 20852, United States
| | - Malliga R Iyer
- Section on Medicinal Chemistry, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rockville, Maryland 20852, United States
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Puthenveetil R, Gómez-Navarro N, Banerjee A. Access and utilization of long chain fatty acyl-CoA by zDHHC protein acyltransferases. Curr Opin Struct Biol 2022; 77:102463. [PMID: 36183446 PMCID: PMC9772126 DOI: 10.1016/j.sbi.2022.102463] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/09/2022] [Accepted: 08/13/2022] [Indexed: 12/24/2022]
Abstract
S-acylation is a reversible posttranslational modification, where a long-chain fatty acid is attached to a protein through a thioester linkage. Being the most abundant form of lipidation in humans, a family of twenty-three human zDHHC integral membrane enzymes catalyze this reaction. Previous structures of the apo and lipid bound zDHHCs shed light into the molecular details of the active site and binding pocket. Here, we delve further into the details of fatty acyl-CoA recognition by zDHHC acyltransferases using insights from the recent structure. We additionally review indirect evidence that suggests acyl-CoAs do not diffuse freely in the cytosol, but are channeled into specific pathways, and comment on the suggested mechanisms for fatty acyl-CoA compartmentalization and intracellular transport, to finally speculate about the potential mechanisms that underlie fatty acyl-CoA delivery to zDHHC enzymes.
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Affiliation(s)
- Robbins Puthenveetil
- Section on Structural and Chemical Biology of Membrane Proteins, Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA. https://twitter.com/RoVeetil
| | - Natalia Gómez-Navarro
- Section on Structural and Chemical Biology of Membrane Proteins, Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA. https://twitter.com/NataliaGmez10
| | - Anirban Banerjee
- Section on Structural and Chemical Biology of Membrane Proteins, Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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5
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Horn CL, Morales AL, Savard C, Farrell GC, Ioannou GN. Role of Cholesterol-Associated Steatohepatitis in the Development of NASH. Hepatol Commun 2021; 6:12-35. [PMID: 34558856 PMCID: PMC8710790 DOI: 10.1002/hep4.1801] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 07/08/2021] [Accepted: 07/14/2021] [Indexed: 12/11/2022] Open
Abstract
The rising prevalence of nonalcoholic fatty liver disease (NAFLD) and NAFLD-related cirrhosis in the United States and globally highlights the need to better understand the mechanisms causing progression of hepatic steatosis to fibrosing steatohepatitis and cirrhosis in a small proportion of patients with NAFLD. Accumulating evidence suggests that lipotoxicity mediated by hepatic free cholesterol (FC) overload is a mechanistic driver for necroinflammation and fibrosis, characteristic of nonalcoholic steatohepatitis (NASH), in many animal models and also in some patients with NASH. Diet, lifestyle, obesity, key genetic polymorphisms, and hyperinsulinemia secondary to insulin resistance are pivotal drivers leading to aberrant cholesterol signaling, which leads to accumulation of FC within hepatocytes. FC overload in hepatocytes can lead to ER stress, mitochondrial dysfunction, development of toxic oxysterols, and cholesterol crystallization in lipid droplets, which in turn lead to hepatocyte apoptosis, necrosis, or pyroptosis. Activation of Kupffer cells and hepatic stellate cells by hepatocyte signaling and cholesterol loading contributes to this inflammation and leads to hepatic fibrosis. Cholesterol accumulation in hepatocytes can be readily prevented or reversed by statins. Observational studies suggest that use of statins in NASH not only decreases the substantially increased cardiovascular risk, but may ameliorate liver pathology. Conclusion: Hepatic FC loading may result in cholesterol-associated steatohepatitis and play an important role in the development and progression of NASH. Statins appear to provide significant benefit in preventing progression to NASH and NASH-cirrhosis. Randomized controlled trials are needed to demonstrate whether statins or statin/ezetimibe combination can effectively reverse steatohepatitis and liver fibrosis in patients with NASH.
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Affiliation(s)
- Christian L Horn
- Division of Gastroenterology and Hepatology, Department of Medicine, San Antonio Military Medical Center, Fort Sam Houston, TX, USA
| | - Amilcar L Morales
- Division of Gastroenterology and Hepatology, Department of Medicine, San Antonio Military Medical Center, Fort Sam Houston, TX, USA
| | - Christopher Savard
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA.,Division of Gastroenterology, Department of Medicine, University of Washington, Seattle, WA, USA.,Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA
| | - Geoffrey C Farrell
- Liver Research Group, ANU Medical School, Australian National University at the Canberra Hospital, Garran, ACT, Australia
| | - George N Ioannou
- Division of Gastroenterology, Department of Medicine, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA.,Division of Gastroenterology, Department of Medicine, University of Washington, Seattle, WA, USA.,Research and Development, Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA
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6
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Li H, Yu XH, Ou X, Ouyang XP, Tang CK. Hepatic cholesterol transport and its role in non-alcoholic fatty liver disease and atherosclerosis. Prog Lipid Res 2021; 83:101109. [PMID: 34097928 DOI: 10.1016/j.plipres.2021.101109] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 12/12/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a quickly emerging global health problem representing the most common chronic liver disease in the world. Atherosclerotic cardiovascular disease represents the leading cause of mortality in NAFLD patients. Cholesterol metabolism has a crucial role in the pathogenesis of both NAFLD and atherosclerosis. The liver is the major organ for cholesterol metabolism. Abnormal hepatic cholesterol metabolism not only leads to NAFLD but also drives the development of atherosclerotic dyslipidemia. The cholesterol level in hepatocytes reflects the dynamic balance between endogenous synthesis, uptake, esterification, and export, a process in which cholesterol is converted to neutral cholesteryl esters either for storage in cytosolic lipid droplets or for secretion as a major constituent of plasma lipoproteins, including very-low-density lipoproteins, chylomicrons, high-density lipoproteins, and low-density lipoproteins. In this review, we describe decades of research aimed at identifying key molecules and cellular players involved in each main aspect of hepatic cholesterol metabolism. Furthermore, we summarize the recent advances regarding the biological processes of hepatic cholesterol transport and its role in NAFLD and atherosclerosis.
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Affiliation(s)
- Heng Li
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China
| | - Xiao-Hua Yu
- Institute of Clinical Medicine, The Second Affiliated Hospital of Hainan Medical University, Haikou, Hainan 460106, China
| | - Xiang Ou
- Department of Endocrinology, the First Hospital of Changsha, Changsha, Hunan 410005, China
| | - Xin-Ping Ouyang
- Department of Physiology, Institute of Neuroscience Research, Hengyang Key Laboratory of Neurodegeneration and Cognitive Impairment, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China.
| | - Chao-Ke Tang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China.
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Colardo M, Martella N, Pensabene D, Siteni S, Di Bartolomeo S, Pallottini V, Segatto M. Neurotrophins as Key Regulators of Cell Metabolism: Implications for Cholesterol Homeostasis. Int J Mol Sci 2021; 22:5692. [PMID: 34073639 PMCID: PMC8198482 DOI: 10.3390/ijms22115692] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 12/14/2022] Open
Abstract
Neurotrophins constitute a family of growth factors initially characterized as predominant mediators of nervous system development, neuronal survival, regeneration and plasticity. Their biological activity is promoted by the binding of two different types of receptors, leading to the generation of multiple and variegated signaling cascades in the target cells. Increasing evidence indicates that neurotrophins are also emerging as crucial regulators of metabolic processes in both neuronal and non-neuronal cells. In this context, it has been reported that neurotrophins affect redox balance, autophagy, glucose homeostasis and energy expenditure. Additionally, the trophic support provided by these secreted factors may involve the regulation of cholesterol metabolism. In this review, we examine the neurotrophins' signaling pathways and their effects on metabolism by critically discussing the most up-to-date information. In particular, we gather experimental evidence demonstrating the impact of these growth factors on cholesterol metabolism.
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Affiliation(s)
- Mayra Colardo
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy; (M.C.); (N.M.); (D.P.); (S.D.B.)
| | - Noemi Martella
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy; (M.C.); (N.M.); (D.P.); (S.D.B.)
| | - Daniele Pensabene
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy; (M.C.); (N.M.); (D.P.); (S.D.B.)
| | - Silvia Siteni
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA;
| | - Sabrina Di Bartolomeo
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy; (M.C.); (N.M.); (D.P.); (S.D.B.)
| | - Valentina Pallottini
- Department of Science, University Roma Tre, Viale Marconi 446, 00146 Rome, Italy;
- Neuroendocrinology Metabolism and Neuropharmacology Unit, IRCSS Fondazione Santa Lucia, Via del Fosso Fiorano 64, 00143 Rome, Italy
| | - Marco Segatto
- Department of Biosciences and Territory, University of Molise, Contrada Fonte Lappone, 86090 Pesche, Italy; (M.C.); (N.M.); (D.P.); (S.D.B.)
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8
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Chen Y, Yang X, Chen Y, Chen G, Winkler CA, An P, Lyu J. Impacts of the SOAT1 genetic variants and protein expression on HBV-related hepatocellular carcinoma. BMC Cancer 2021; 21:615. [PMID: 34039309 PMCID: PMC8152151 DOI: 10.1186/s12885-021-08245-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 04/23/2021] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) remains a major public health problem and its pathogenesis remains unresolved. A recent proteomics study discovered a lipid enzyme Sterol O-acyltransferase (SOAT1) involvement in the progression of HCC. We aimed to explore the association between SOAT1 genetic variation and HCC. METHODS We genotyped three exonic SOAT1 variants (rs10753191, V323V; rs3753526, L475L; rs13306731, Q526R) tagging most variations in the gene, in 221 HCC patients and 229 healthy individuals, to assess the impact of SOAT1 gene variation on risk of HCC occurrence. We further conducted immunohistochemistry to compare SOAT1 protein expression levels in 42 paired tumor and adjacent non-tumor tissues. RESULTS We found that rs10753191 (Odds ratio (OR) = 0.58, P = 0.04) and a haplotype TGA (OR = 0.40, P = 0.01) were associated with reduced HCC risk after adjusting for lipid levels. In the immunohistochemistry experiment, we found that the protein expression of SOAT1 was significantly increased in the tumor compared with adjacent tissue (P < 0.001). CONCLUSION This study revealed for the first time SOAT1 genetic variation that associates with host susceptibility to HCC occurrence. Our results suggest a role of SOAT1 in the HCC development, which warrants further elucidation.
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Affiliation(s)
- Yulong Chen
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xunjun Yang
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, Zhejiang, China
- Department of Laboratory Medicine, The Second Affiliated Hospital & Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yao Chen
- Department of Pathology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Guorong Chen
- Department of Pathology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Cheryl A Winkler
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Ping An
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA.
| | - Jianxin Lyu
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, Zhejiang, China.
- Zhejiang Provincial People's Hospital, Affiliated Hospital of Hangzhou Medical College, Zhejiang, Hangzhou, China.
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9
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Giacomini I, Gianfanti F, Desbats MA, Orso G, Berretta M, Prayer-Galetti T, Ragazzi E, Cocetta V. Cholesterol Metabolic Reprogramming in Cancer and Its Pharmacological Modulation as Therapeutic Strategy. Front Oncol 2021; 11:682911. [PMID: 34109128 PMCID: PMC8181394 DOI: 10.3389/fonc.2021.682911] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/06/2021] [Indexed: 12/14/2022] Open
Abstract
Cholesterol is a ubiquitous sterol with many biological functions, which are crucial for proper cellular signaling and physiology. Indeed, cholesterol is essential in maintaining membrane physical properties, while its metabolism is involved in bile acid production and steroid hormone biosynthesis. Additionally, isoprenoids metabolites of the mevalonate pathway support protein-prenylation and dolichol, ubiquinone and the heme a biosynthesis. Cancer cells rely on cholesterol to satisfy their increased nutrient demands and to support their uncontrolled growth, thus promoting tumor development and progression. Indeed, transformed cells reprogram cholesterol metabolism either by increasing its uptake and de novo biosynthesis, or deregulating the efflux. Alternatively, tumor can efficiently accumulate cholesterol into lipid droplets and deeply modify the activity of key cholesterol homeostasis regulators. In light of these considerations, altered pathways of cholesterol metabolism might represent intriguing pharmacological targets for the development of exploitable strategies in the context of cancer therapy. Thus, this work aims to discuss the emerging evidence of in vitro and in vivo studies, as well as clinical trials, on the role of cholesterol pathways in the treatment of cancer, starting from already available cholesterol-lowering drugs (statins or fibrates), and moving towards novel potential pharmacological inhibitors or selective target modulators.
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Affiliation(s)
- Isabella Giacomini
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Federico Gianfanti
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
- Veneto Institute of Molecular Medicine, VIMM, Padova, Italy
| | | | - Genny Orso
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Massimiliano Berretta
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Tommaso Prayer-Galetti
- Department of Surgery, Oncology and Gastroenterology - Urology, University of Padova, Padova, Italy
| | - Eugenio Ragazzi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Veronica Cocetta
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
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Hedgehog Acyltransferase Promotes Uptake of Palmitoyl-CoA across the Endoplasmic Reticulum Membrane. Cell Rep 2020; 29:4608-4619.e4. [PMID: 31875564 PMCID: PMC6948154 DOI: 10.1016/j.celrep.2019.11.110] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 10/29/2019] [Accepted: 11/26/2019] [Indexed: 12/14/2022] Open
Abstract
Attachment of palmitate to the N terminus of Sonic hedgehog (Shh) is essential for Shh signaling. Shh palmitoylation is catalyzed on the luminal side of the endoplasmic reticulum (ER) by Hedgehog acyltransferase (Hhat), an ER-resident enzyme. Palmitoyl-coenzyme A (CoA), the palmitate donor, is produced in the cytosol and is not permeable across membrane bilayers. It is not known how palmitoyl-CoA crosses the ER membrane to access the active site of Hhat. Here, we use fluorescent and radiolabeled palmitoyl-CoA probes to demonstrate that Hhat promotes the uptake of palmitoyl-CoA across the ER membrane in microsomes and semi-intact cells. Reconstitution of purified Hhat into liposomes provided further evidence that palmitoyl-CoA uptake activity is an intrinsic property of Hhat. Palmitoyl-CoA uptake was regulated by and could be uncoupled from Hhat enzymatic activity, implying that Hhat serves a dual function as a palmitoyl acyltransferase and a conduit to supply palmitoyl-CoA to the luminal side of the ER. Palmitoylation of hedgehog proteins by Hedgehog acyltransferase (Hhat) occurs on the luminal side of the ER. However, the palmitoyl-CoA donor for the reaction is membrane impermeable. Asciolla and Resh show that Hhat serves a dual function as both an acyltransferase and a transporter that promotes palmitoyl-CoA uptake across the ER membrane.
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11
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Moose JE, Leets KA, Mate NA, Chisholm JD, Hougland JL. An overview of ghrelin O-acyltransferase inhibitors: a literature and patent review for 2010-2019. Expert Opin Ther Pat 2020; 30:581-593. [PMID: 32564644 DOI: 10.1080/13543776.2020.1776263] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION The peptide hormone ghrelin regulates physiological processes associated with energy homeostasis such as appetite, insulin signaling, glucose metabolism, and adiposity. Ghrelin has also been implicated in a growing number of neurological pathways involved in stress response and addiction behavior. For ghrelin to bind the growth hormone secretagogue receptor 1a (GHS-R1a) and activate signaling, the hormone must first be octanoylated on a specific serine side chain. This key transformation is performed by the enzyme ghrelin O-acyltransferase (GOAT), and therefore GOAT inhibitors may be useful in treating disorders related to ghrelin signaling such as diabetes, obesity, and related metabolic syndromes. AREAS COVERED This report covers ghrelin and GOAT as potential therapeutic targets and summarizes work on GOAT inhibitors through the end of 2019, highlighting recent successes with both peptidomimetics and small molecule GOAT inhibitors as potent modulators of GOAT-catalyzed ghrelin octanoylation. EXPERT OPINION A growing body of biochemical and structural knowledge regarding the ghrelin/GOAT system now enables multiple avenues for identifying and optimizing GOAT inhibitors. We are at the beginning of a new era with increased opportunities for leveraging ghrelin and GOAT in the understanding and treatment of multiple health conditions including diabetes, obesity, and addiction.
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Affiliation(s)
- Jacob E Moose
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - Katelyn A Leets
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - Nilamber A Mate
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - John D Chisholm
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
| | - James L Hougland
- Department of Chemistry and BioInspired Syracuse, Syracuse University , Syracuse, NY, USA
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12
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Guan C, Niu Y, Chen SC, Kang Y, Wu JX, Nishi K, Chang CCY, Chang TY, Luo T, Chen L. Structural insights into the inhibition mechanism of human sterol O-acyltransferase 1 by a competitive inhibitor. Nat Commun 2020; 11:2478. [PMID: 32424158 PMCID: PMC7234994 DOI: 10.1038/s41467-020-16288-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/24/2020] [Indexed: 01/04/2023] Open
Abstract
Sterol O-acyltransferase 1 (SOAT1) is an endoplasmic reticulum (ER) resident, multi-transmembrane enzyme that belongs to the membrane-bound O-acyltransferase (MBOAT) family. It catalyzes the esterification of cholesterol to generate cholesteryl esters for cholesterol storage. SOAT1 is a target to treat several human diseases. However, its structure and mechanism remain elusive since its discovery. Here, we report the structure of human SOAT1 (hSOAT1) determined by cryo-EM. hSOAT1 is a tetramer consisted of a dimer of dimer. The structure of hSOAT1 dimer at 3.5 Å resolution reveals that a small molecule inhibitor CI-976 binds inside the catalytic chamber and blocks the accessibility of the active site residues H460, N421 and W420. Our results pave the way for future mechanistic study and rational drug design targeting hSOAT1 and other mammalian MBOAT family members.
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Affiliation(s)
- Chengcheng Guan
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking University, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, 100871, Beijing, China
| | - Yange Niu
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking University, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, 100871, Beijing, China
| | - Si-Cong Chen
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education and Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, 100871, Beijing, China
| | - Yunlu Kang
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking University, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, 100871, Beijing, China
| | - Jing-Xiang Wu
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking University, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, 100871, Beijing, China
| | - Koji Nishi
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Catherine C Y Chang
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Ta-Yuan Chang
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH, 03755, USA
| | - Tuoping Luo
- Key Laboratory of Bioorganic Chemistry and Molecular Engineering, Ministry of Education and Beijing National Laboratory for Molecular Science, College of Chemistry and Molecular Engineering, Peking University, 100871, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Peking University, 100871, Beijing, China
- Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China
| | - Lei Chen
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking University, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, 100871, Beijing, China.
- Peking-Tsinghua Center for Life Sciences, Peking University, 100871, Beijing, China.
- Academy for Advanced Interdisciplinary Studies, Peking University, 100871, Beijing, China.
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Iqbal J, Jahangir Z, Al-Qarni AA. Microsomal Triglyceride Transfer Protein: From Lipid Metabolism to Metabolic Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1276:37-52. [DOI: 10.1007/978-981-15-6082-8_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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14
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Mechanisms and regulation of cholesterol homeostasis. Nat Rev Mol Cell Biol 2019; 21:225-245. [DOI: 10.1038/s41580-019-0190-7] [Citation(s) in RCA: 450] [Impact Index Per Article: 90.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2019] [Indexed: 12/14/2022]
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15
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Infectious Bursal Disease Virus Hijacks Endosomal Membranes as the Scaffolding Structure for Viral Replication. J Virol 2018. [PMID: 29540593 DOI: 10.1128/jvi.01964-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Birnaviruses are unconventional members of the group of double-stranded RNA (dsRNA) viruses that are characterized by the lack of a transcriptionally active inner core. Instead, the birnaviral particles organize their genome in ribonucleoprotein complexes (RNPs) composed by dsRNA segments, the dsRNA-binding VP3 protein, and the virally encoded RNA-dependent RNA polymerase (RdRp). This and other structural features suggest that birnaviruses may follow a completely different replication program from that followed by members of the Reoviridae family, supporting the hypothesis that birnaviruses are the evolutionary link between single-stranded positive RNA (+ssRNA) and dsRNA viruses. Here we demonstrate that infectious bursal disease virus (IBDV), a prototypical member of the Birnaviridae family, hijacks endosomal membranes of infected cells through the interaction of a viral protein, VP3, with the phospholipids on the cytosolic leaflet of these compartments for replication. Employing a mutagenesis approach, we demonstrated that VP3 domain PATCH 2 (P2) mediates the association of VP3 with the endosomal membranes. To determine the role of VP3 P2 in the context of the virus replication cycle, we used avian cells stably overexpressing VP3 P2 for IBDV infection. Importantly, the intra- and extracellular virus yields, as well as the intracellular levels of VP2 viral capsid protein, were significantly diminished in cells stably overexpressing VP3 P2. Together, our results indicate that the association of VP3 with endosomes has a relevant role in the IBDV replication cycle. This report provides direct experimental evidence for membranous compartments such as endosomes being required by a dsRNA virus for its replication. The results also support the previously proposed role of birnaviruses as an evolutionary link between +ssRNA and dsRNA viruses.IMPORTANCE Infectious bursal disease (IBD; also called Gumboro disease) is an acute, highly contagious immunosuppressive disease that affects young chickens and spreads worldwide. The etiological agent of IBD is infectious bursal disease virus (IBDV). This virus destroys the central immune organ (bursa of Fabricius), resulting in immunosuppression and reduced responses of chickens to vaccines, which increase their susceptibility to other pathogens. IBDV is a member of Birnaviridae family, which comprises unconventional members of dsRNA viruses, whose replication strategy has been scarcely studied. In this report we show that IBDV hijacks the endosomes of the infected cells for establishing viral replication complexes via the association of the ribonucleoprotein complex component VP3 with the phospholipids in the cytosolic leaflet of endosomal membranes. We show that this interaction is mediated by the VP3 PATCH 2 domain and demonstrate its relevant role in the context of viral infection.
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Korber M, Klein I, Daum G. Steryl ester synthesis, storage and hydrolysis: A contribution to sterol homeostasis. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1534-1545. [DOI: 10.1016/j.bbalip.2017.09.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 08/25/2017] [Accepted: 09/05/2017] [Indexed: 02/01/2023]
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17
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Wang YT, Wang YH, Ma YT, Fu ZY, Yang YN, Ma X, Li XM, Adi D, Liu F, Chen BD. ACAT-1 gene polymorphism is associated with increased susceptibility to coronary artery disease in Chinese Han population: a case-control study. Oncotarget 2017; 8:89055-89063. [PMID: 29179498 PMCID: PMC5687668 DOI: 10.18632/oncotarget.21649] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 08/27/2017] [Indexed: 02/06/2023] Open
Abstract
Several studies suggest an important role of Acyl-CoA: cholesterol acyltransferase-1(ACAT-1) in the development of atherosclerosis. The aim of present study was to investigate whether there exists a possible correlation between genetic variations in ACAT-1 genes and coronary artery disease (CAD) risk. Four polymorphisms (rs1044925, rs11545566, rs12121758 and rs10913733) were finally selected and genotyped in 750 CAD patients and 580 health controls, using the improved multiplex ligation detection reaction (iMLDR) method. We found that the rs11545566 G allele was associated with a significantly elevated CAD risk [GG vs. AA: adjusted odds ratio (AOR) = 1.62, 95% confidence interval (CI) = 1.13-2.32, P = 0.008; GA/GG vs. AA: AOR = 1.67, 95% CI = 1.22-2.29, P = 0.001]. The rs10913733 G allele was also associated with a significantly elevated CAD risk (GG vs. TT: AOR = 1.57, 95% CI = 1.08-2.28, P = 0.018; GT/GG vs. TT: AOR = 1.39, 95% CI = 1.07-1.79, P = 0.013). Multivariate linear regression analysis showed that the rs11545566 polymorphism was independently associated with the Gensini scores (P = 0.005). The Gensini score of subjects in the variant GG genotype group and the GG/GA genotype group were higher than the score of subjects in the AA genotype group (32.49 ± 26.60 and 31.26 ± 26.96 vs. 23.45 ± 21.64; P = 0.001 and 0.002, respectively). Our results demonstrate that ACAT-1 rs1154556 and rs10913733 polymorphism are novel genetic factors in the development of CAD. Rs11545566 was also associated with the severity of CAD.
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Affiliation(s)
- Yong-Tao Wang
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi 830054, P.R. China
| | - Ying-Hong Wang
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi 830054, P.R. China
| | - Yi-Tong Ma
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi 830054, P.R. China
| | - Zhen-Yan Fu
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi 830054, P.R. China
| | - Yi-Ning Yang
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi 830054, P.R. China
| | - Xiang Ma
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi 830054, P.R. China
| | - Xiao-Mei Li
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi 830054, P.R. China
| | - Dilare Adi
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi 830054, P.R. China
| | - Fen Liu
- Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi 830054, P.R. China
| | - Bang-Dang Chen
- Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi 830054, P.R. China
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18
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Abstract
Beauveriolide III (BeauIII) inhibited sterol O-acyltransferases 1 and 2 (SOAT1 and SOAT2), which are endoplasmic reticulum (ER) membrane proteins, in an enzyme-based assay, and selectively inhibited SOAT1 in a cell-based assay using SOAT1-/SOAT2-CHO cells. This discrepancy in SOAT inhibition by BeauIII was investigated. In the enzyme-based assay, BeauIII inhibited SOAT1 and SOAT2 to a similar extent using microsomes prepared from cells disrupted under the strongest sonication condition. In semi-intact SOAT1-/SOAT2-CHO cells prepared by a treatment with digitonin (plasma membrane permeabilized), BeauIII selectively inhibited SOAT1 (IC50; 5.0 µM (SOAT1) vs >90 µM (SOAT2)), while in those treated with saponin (plasma membrane and ER membrane permeabilized), BeauIII inhibited SOAT1 (IC50, 1.8 µM) and SOAT2 (5.9 µM). SOAT1-selective inhibition by BeauIII was reproduced in intact ER fractions prepared from SOAT1/SOAT2-CHO cells. A Western blotting analysis revealed that biotin-labeled beauveriolide bound to the SOAT1 protein prepared from SOAT1-CHO cells. We concluded that BeauIII binds to a putative active site responsible for SOAT1 that is located on the cytosolic side of the ER, while BeauIII is not accessible to the corresponding active site for SOAT2 located on the luminal side.
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Pal P, Gandhi HP, Kanhed AM, Patel NR, Mankadia NN, Baldha SN, Barmade MA, Murumkar PR, Yadav MR. Vicinal diaryl azole-based urea derivatives as potential cholesterol lowering agents acting through inhibition of SOAT enzymes. Eur J Med Chem 2017; 130:107-123. [PMID: 28242547 DOI: 10.1016/j.ejmech.2017.02.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 02/13/2017] [Accepted: 02/14/2017] [Indexed: 10/20/2022]
Abstract
A novel series of vicinal diaryl azole-urea derivatives were synthesized and evaluated for their potential to inhibit SOAT enzyme. Among the reported compounds, compound (12d) emerged as the most potent compound with an IC50 value of 2.43 μM. In polaxamer-407 induced lipoprotein lipase inhibition model, compound (12d) reduced triglyceride turnover in vivo. Compound (12d) also showed dose-dependent prevention of serum total cholesterol and prevention of LDL-C elevation at a dose of 30 mg/kg. Furthermore, compound (12d) showed potential to stop falling levels of serum HDL-C dose-dependently and improved the atherogenic index. Effect of 12d on body weight, plaque formation and development of atherogenic lesions were studied. Toxicological study of compound (12d) indicated that at a dose of 2000 mg/kg, 12d was devoid of any signs of toxicity or mortality.
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Affiliation(s)
- Palash Pal
- Faculty of Pharmacy, Kalabhavan Campus, The Maharaja Sayajirao University of Baroda, Vadodara, 390001, India
| | - Hardik P Gandhi
- Faculty of Pharmacy, Kalabhavan Campus, The Maharaja Sayajirao University of Baroda, Vadodara, 390001, India
| | - Ashish M Kanhed
- Faculty of Pharmacy, Kalabhavan Campus, The Maharaja Sayajirao University of Baroda, Vadodara, 390001, India
| | - Nirali R Patel
- Faculty of Pharmacy, Kalabhavan Campus, The Maharaja Sayajirao University of Baroda, Vadodara, 390001, India
| | - Niraj N Mankadia
- Faculty of Pharmacy, Kalabhavan Campus, The Maharaja Sayajirao University of Baroda, Vadodara, 390001, India
| | - Satish N Baldha
- Faculty of Pharmacy, Kalabhavan Campus, The Maharaja Sayajirao University of Baroda, Vadodara, 390001, India
| | - Mahesh A Barmade
- Faculty of Pharmacy, Kalabhavan Campus, The Maharaja Sayajirao University of Baroda, Vadodara, 390001, India
| | - Prashant R Murumkar
- Faculty of Pharmacy, Kalabhavan Campus, The Maharaja Sayajirao University of Baroda, Vadodara, 390001, India
| | - Mange Ram Yadav
- Faculty of Pharmacy, Kalabhavan Campus, The Maharaja Sayajirao University of Baroda, Vadodara, 390001, India.
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20
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Guo X, Fan C, Chen Y, Wang J, Yin W, Wang RRC, Hu Z. Identification and characterization of an efficient acyl-CoA: diacylglycerol acyltransferase 1 (DGAT1) gene from the microalga Chlorella ellipsoidea. BMC PLANT BIOLOGY 2017; 17:48. [PMID: 28222675 PMCID: PMC5319178 DOI: 10.1186/s12870-017-0995-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Accepted: 02/02/2017] [Indexed: 05/06/2023]
Abstract
BACKGROUND Oil in the form of triacylglycerols (TAGs) is quantitatively the most important storage form of energy for eukaryotic cells. Diacylglycerol acyltransferase (DGAT) is considered the rate-limiting enzyme for TAG accumulation. Chlorella, a unicellular eukaryotic green alga, has attracted much attention as a potential feedstock for renewable energy production. However, the function of DGAT1 in Chlorella has not been reported. RESULTS A full-length cDNA encoding a putative diacylglycerol acyltransferase 1 (DGAT1, EC 2.3.1.20) was obtained from Chlorella ellipsoidea. The 2,142 bp open reading frame of this cDNA, designated CeDGAT1, encodes a protein of 713 amino acids showing no more than 40% identity with DGAT1s of higher plants. Transcript analysis showed that the expression level of CeDGAT1 markedly increased under nitrogen starvation, which led to significant triacylglycerol (TAG) accumulation. CeDGAT1 activity was confirmed in the yeast quadruple mutant strain H1246 by restoring its ability to produce TAG. Upon expression of CeDGAT1, the total fatty acid content in wild-type yeast (INVSc1) increased by 142%, significantly higher than that transformed with DGAT1s from higher plants, including even the oil crop soybean. The over-expression of CeDGAT1 under the NOS promoter in wild-type Arabidopsis thaliana and Brassica napus var. Westar significantly increased the oil content by 8-37% and 12-18% and the average 1,000-seed weight by 9-15% and 6-29%, respectively, but did not alter the fatty acid composition of the seed oil. The net increase in the 1,000-seed total lipid content was up to 25-50% in both transgenic Arabidopsis and B. napus. CONCLUSIONS We identified a gene encoding DGAT1 in C. ellipsoidea and confirmed that it plays an important role in TAG accumulation. This is the first functional analysis of DGAT1 in Chlorella. This information is important for understanding lipid synthesis and accumulation in Chlorella and for genetic engineering to enhance oil production in microalgae and oil plants.
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Affiliation(s)
- Xuejie Guo
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Chengming Fan
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Yuhong Chen
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Jingqiao Wang
- Institute of Economical Crops, Yunnan Agricultural Academy, Kunming, 65023 China
| | - Weibo Yin
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Richard R. C. Wang
- United States Department of Agriculture, Agricultural Research Service, Forage and Range Research Laboratory, Utah State University, Logan, UT 84322-6300 USA
| | - Zanmin Hu
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
- Present address: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing, 100101 China
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Chang NY, Chan YJ, Ding ST, Lee YH, HuangFu WC, Liu IH. Sterol O-Acyltransferase 2 Contributes to the Yolk Cholesterol Trafficking during Zebrafish Embryogenesis. PLoS One 2016; 11:e0167644. [PMID: 27936201 PMCID: PMC5147938 DOI: 10.1371/journal.pone.0167644] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 11/17/2016] [Indexed: 11/18/2022] Open
Abstract
To elucidate whether Sterol O-acyltransferase (Soat) mediates the absorption and transportation of yolk lipids to the developing embryo, zebrafish soat1 and soat2 were cloned and studied. In the adult zebrafish, soat1 was detected ubiquitously while soat2 mRNA was detected specifically in the liver, intestine, brain and testis. Whole mount in situ hybridization demonstrated that both soat1 and soat2 expressed in the yolk syncytial layer, hatching gland and developing cardiovascular as well as digestive systems, suggesting that Soats may play important roles in the lipid trafficking and utilization during embryonic development. The enzymatic activity of zebrafish Soat2 was confirmed by Oil Red O staining in the HEK293 cells overexpressing this gene, and could be quenched by Soat2 inhibitor Pyripyropene A (PPPA). The zebrafish embryos injected with PPPA or morpholino oligo against soat2 in the yolk showed significantly larger yolk when compared with wild-type embryos, especially at 72 hpf, indicating a slower rate of yolk consumption. Our result indicated that zebrafish Soat2 is catalytically active in synthesizing cholesteryl esters and contributes to the yolk cholesterol trafficking during zebrafish embryogenesis.
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Affiliation(s)
- Nai-Yun Chang
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan
| | - Yen-Ju Chan
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan
| | - Shih-Torng Ding
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan
- Institute of Biotechnology, National Taiwan University, Taipei, Taiwan
| | - Yen-Hua Lee
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan
| | - Wei-Chun HuangFu
- The Ph.D. Program for Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - I-Hsuan Liu
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan
- Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan
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Determination of the topology of endoplasmic reticulum membrane proteins using redox-sensitive green-fluorescence protein fusions. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:1672-82. [PMID: 25889538 DOI: 10.1016/j.bbamcr.2015.04.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 03/30/2015] [Accepted: 04/02/2015] [Indexed: 02/01/2023]
Abstract
Membrane proteins of the endoplasmic reticulum (ER) are involved in a wide array of essential cellular functions. Identification of the topology of membrane proteins can provide significant insight into their mechanisms of action and biological roles. This is particularly important for membrane enzymes, since their topology determines the subcellular site where a biochemical reaction takes place and the dependence on luminal or cytosolic co-factor pools and substrates. The methods currently available for the determination of topology of proteins are rather laborious and require post-lysis or post-fixation manipulation of cells. In this work, we have developed a simple method for defining intracellular localization and topology of ER membrane proteins in living cells, based on the fusion of the respective protein with redox-sensitive green-fluorescent protein (roGFP). We validated the method and demonstrated that roGFP fusion proteins constitute a reliable tool for the study of ER membrane protein topology, using as control microsomal 11β-hydroxysteroid dehydrogenase (11β-HSD) proteins whose topology has been resolved, and comparing with an independent approach. We then implemented this method to determine the membrane topology of six microsomal members of the 17β-hydroxysteroid dehydrogenase (17β-HSD) family. The results revealed a luminal orientation of the catalytic site for three enzymes, i.e. 17β-HSD6, 7 and 12. Knowledge of the intracellular location of the catalytic site of these enzymes will enable future studies on their biological functions and on the role of the luminal co-factor pool.
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Abstract
INTRODUCTION Acyltransferase (AT) catalyzes the transfer of an acyl moiety from acyl-coenzyme A (acyl-CoA) to an acceptor. ATs play important roles in the maintenance of homeostasis in the human body and have been linked to various diseases; therefore, several ATs have been proposed as potential targets for the treatment or prevention of such diseases. The AT family includes acyl-CoA:cholesterol AT (ACAT), diacylglycerol AT (DGAT), and monoacylglycerol AT (MGAT) for the metabolism of lipids. Furthermore, recent molecular biological studies revealed the existence of their isozymes with distinct functions in the body. AREAS COVERED This review summarized patent filings published between 2010 and the present date that claimed isozyme-selective inhibitors of ACAT, DGAT and MGAT, which are involved in neutral lipid metabolism. EXPERT OPINION Isozymes of ACAT, DGAT and MGAT play distinct functions in neutral lipid metabolism in the human body and have been considered as potential therapeutic targets. Accordingly, isozyme-selective inhibitors that could be used in the treatment or prevention of lipid metabolism disorders were searched for. Of these, pyripyropene A derivatives, ACAT2-selective inhibitors, may be potential therapeutics for the treatment of atherosclerosis, homozygous familial hypercholesterolemia and nonalcoholic fatty liver disease.
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Affiliation(s)
- Taichi Ohshiro
- Kitasato University, Graduate School of Pharmaceutical Sciences , 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641 , Japan
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24
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Sodhi SS, Ghosh M, Song KD, Sharma N, Kim JH, Kim NE, Lee SJ, Kang CW, Oh SJ, Jeong DK. An approach to identify SNPs in the gene encoding acetyl-CoA acetyltransferase-2 (ACAT-2) and their proposed role in metabolic processes in pig. PLoS One 2014; 9:e102432. [PMID: 25050817 PMCID: PMC4106792 DOI: 10.1371/journal.pone.0102432] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 06/17/2014] [Indexed: 12/01/2022] Open
Abstract
The novel liver protein acetyl-CoA acetyltransferase-2 (ACAT2) is involved in the beta-oxidation and lipid metabolism. Its comprehensive relative expression, in silico non-synonymous single nucleotide polymorphism (nsSNP) analysis, as well as its annotation in terms of metabolic process with another protein from the same family, namely, acetyl-CoA acyltransferase-2 (ACAA2) was performed in Sus scrofa. This investigation was conducted to understand the most important nsSNPs of ACAT2 in terms of their effects on metabolic activities and protein conformation. The two most deleterious mutations at residues 122 (I to V) and 281 (R to H) were found in ACAT2. Validation of expression of genes in the laboratory also supported the idea of differential expression of ACAT2 and ACAA2 conceived through the in silico analysis. Analysis of the relative expression of ACAT2 and ACAA2 in the liver tissue of Jeju native pig showed that the former expressed significantly higher (P<0.05). Overall, the computational prediction supported by wet laboratory analysis suggests that ACAT2 might contribute more to metabolic processes than ACAA2 in swine. Further associations of SNPs in ACAT2 with production traits might guide efforts to improve growth performance in Jeju native pigs.
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Affiliation(s)
- Simrinder Singh Sodhi
- Department of Animal Biotechnology, Faculty of Biotechnology, Jeju National University, Jeju-si, Jeju-do, South Korea
| | - Mrinmoy Ghosh
- Department of Animal Biotechnology, Faculty of Biotechnology, Jeju National University, Jeju-si, Jeju-do, South Korea
| | - Ki Duk Song
- The Animal Genomics and Breeding Center, Hankyong National University, Anseong-si, Gyeonggi-do, South Korea
| | - Neelesh Sharma
- Department of Animal Biotechnology, Faculty of Biotechnology, Jeju National University, Jeju-si, Jeju-do, South Korea
| | - Jeong Hyun Kim
- Department of Animal Biotechnology, Faculty of Biotechnology, Jeju National University, Jeju-si, Jeju-do, South Korea
| | - Nam Eun Kim
- Department of Animal Biotechnology, Faculty of Biotechnology, Jeju National University, Jeju-si, Jeju-do, South Korea
| | - Sung Jin Lee
- Department of Animal Biotechnology, College of Animal Bioscience and Technology, Kangwon National University, Chuncheon, South Korea
| | - Chul Woong Kang
- Department of Mechanical and System Engineering, College of Engineering, Jeju National University, Jeju-si, Jeju-do, South Korea
| | - Sung Jong Oh
- Department of Animal Biotechnology, Faculty of Biotechnology, Jeju National University, Jeju-si, Jeju-do, South Korea
| | - Dong Kee Jeong
- Department of Animal Biotechnology, Faculty of Biotechnology, Jeju National University, Jeju-si, Jeju-do, South Korea
- Sustainable Agriculture Research Institute (SARI), Jeju National University, Jeju-si, Jeju-do, South Korea
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Association between single nucleotide polymorphism rs1044925 and the risk of coronary artery disease and ischemic stroke. Int J Mol Sci 2014; 15:3546-59. [PMID: 24577316 PMCID: PMC3975353 DOI: 10.3390/ijms15033546] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 01/30/2014] [Accepted: 02/13/2014] [Indexed: 11/16/2022] Open
Abstract
The present study was performed to clarify the association between the acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) single nucleotide polymorphism (SNP) rs1044925 and the risk of coronary artery disease (CAD) and ischemic stroke (IS) in the Guangxi Han population. Polymerase chain reaction and restriction fragment length polymorphism was performed to determine the genotypes of the ACAT-1 SNP rs1044925 in 1730 unrelated subjects (CAD, 587; IS, 555; and healthy controls; 588). The genotypic and allelic frequencies of rs1044925 were significantly different between the CAD patients and controls (p = 0.015) and borderline different between the IS patients and controls (p = 0.05). The AC/CC genotypes and C allele were associated with a decreased risk of CAD and IS (CAD: p = 0.014 for AC/CC vs. AA, p = 0.022 for C vs. A; IS: p = 0.014 for AC/CC vs. AA; p = 0.017 for C vs. A). The AC/CC genotypes in the healthy controls, but not in CAD or IS patients, were associated with an increased serum high-density lipoprotein cholesterol (HDL-C) concentration. The present study shows that the C allele carriers of ACAT-1 rs1044925 were associated with an increased serum HDL-C level in the healthy controls and decreased risk in CAD and IS patients.
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Guo HH, Wang TT, Li QQ, Zhao N, Zhang Y, Liu D, Hu Q, Li FL. Two novel diacylglycerol acyltransferase genes from Xanthoceras sorbifolia are responsible for its seed oil content. Gene 2013; 527:266-74. [DOI: 10.1016/j.gene.2013.05.076] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 05/10/2013] [Accepted: 05/28/2013] [Indexed: 01/31/2023]
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Li M, Zhao M, Wu H, Wu W, Xu Y. Cloning, characterization and functional analysis of two type 1 diacylglycerol acyltransferases (DGAT1s) from Tetraena mongolica. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2013; 55:490-503. [PMID: 23480422 DOI: 10.1111/jipb.12046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 02/09/2013] [Indexed: 06/01/2023]
Abstract
Two cDNAs encoding putative type 1 acyl-CoA: diacylglycerol acyltransferases (DGAT1, EC 2.3.1.20), were cloned from Tetraena mongolica, an extreme xerophyte with high oil content in the stems. The 1 488-bp and 1 485-bp of the open reading frame (ORF) of the two cDNAs, designated as TmDGAT1a and TmDGAT1b, were both predicted to encode proteins of 495 and 494 amino acids, respectively. Southern blot analysis revealed that TmDGAT1a and TmDGAT1b both had low copy numbers in the T. mongolica genome. In addition to ubiquitous expression with different intensity in different tissues, including stems, leaves and roots, TmDGAT1a and TmDGAT1b, were found to be strongly induced by high salinity, drought and osmotic stress, resulting in a remarkable increase of triacylglycerol (TAG) accumulation in T. mongolica plantlets. TmDGAT1a and TmDGAT1b activities were confirmed in the yeast H1246 quadruple mutant (DGA1, LRO1, ARE1, ARE2) by restoring DGAT activity of the mutant host to produce TAG. Overexpression of TmDGAT1a and TmDGAT1b in soybean hairy roots as well as in T. mongolica calli both resulted in an increase in oil content (ranging from 37% to 108%), accompanied by altered fatty acid profiles.
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Affiliation(s)
- Minchun Li
- Key Laboratory of Photobiology, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China
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Lige B, Sampels V, Coppens I. Characterization of a second sterol-esterifying enzyme in Toxoplasma highlights the importance of cholesterol storage pathways for the parasite. Mol Microbiol 2013; 87:951-67. [PMID: 23374239 DOI: 10.1111/mmi.12142] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2012] [Indexed: 11/28/2022]
Abstract
Lipid bodies are eukaryotic structures for temporary storage of neutral lipids such as acylglycerols and steryl esters. Fatty acyl-CoA and cholesterol are two substrates for cholesteryl ester (CE) synthesis via the ACAT reaction. The intracellular parasite Toxoplasma gondii is incapable of sterol synthesis and unremittingly scavenges cholesterol from mammalian host cells. We previously demonstrated that the parasite expresses a cholesteryl ester-synthesizing enzyme, TgACAT1. In this article, we identified and characterized a second ACAT-like enzyme, TgACAT2, which shares 56% identity with TgACAT1. Both enzymes are endoplasmic reticulum-associated and contribute to CE formation for storage in lipid bodies. While TgACAT1 preferentially utilizes palmitoyl-CoA, TgACAT2 has broader fatty acid specificity and produces more CE. Genetic ablation of each individual ACAT results in parasite growth impairment whereas dual ablation of ACAT1 and ACAT2 is not tolerated by Toxoplasma. ΔACAT1 and ΔACAT2 parasites have reduced CE levels, fewer lipid bodies, and accumulate free cholesterol, which causes injurious membrane effects. Mutant parasites are particularly vulnerable to ACAT inhibitors. This study underlines the important physiological role of ACAT enzymes to store cholesterol in a sterol-auxotrophic organism such as Toxoplasma, and furthermore opens up possibilities of exploiting TgACAT as targets for the development of antitoxoplasmosis drugs.
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Affiliation(s)
- Bao Lige
- Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA
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Hussain MM, Rava P, Walsh M, Rana M, Iqbal J. Multiple functions of microsomal triglyceride transfer protein. Nutr Metab (Lond) 2012; 9:14. [PMID: 22353470 PMCID: PMC3337244 DOI: 10.1186/1743-7075-9-14] [Citation(s) in RCA: 182] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 02/21/2012] [Indexed: 02/08/2023] Open
Abstract
Microsomal triglyceride transfer protein (MTP) was first identified as a major cellular protein capable of transferring neutral lipids between membrane vesicles. Its role as an essential chaperone for the biosynthesis of apolipoprotein B (apoB)-containing triglyceride-rich lipoproteins was established after the realization that abetalipoproteinemia patients carry mutations in the MTTP gene resulting in the loss of its lipid transfer activity. Now it is known that it also plays a role in the biosynthesis of CD1, glycolipid presenting molecules, as well as in the regulation of cholesterol ester biosynthesis. In this review, we will provide a historical perspective about the identification, purification and characterization of MTP, describe methods used to measure its lipid transfer activity, and discuss tissue expression and function. Finally, we will review the role MTP plays in the assembly of apoB-lipoprotein, the regulation of cholesterol ester synthesis, biosynthesis of CD1 proteins and propagation of hepatitis C virus. We will also provide a brief overview about the clinical potentials of MTP inhibition.
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Affiliation(s)
- M Mahmood Hussain
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Paul Rava
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Meghan Walsh
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Muhammad Rana
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Jahangir Iqbal
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
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Wu DF, Yin RX, Aung LHH, Li Q, Yan TT, Zeng XN, Huang KK, Huang P, Wu JZ, Pan SL. Sex-specific association of ACAT-1 rs1044925 SNP and serum lipid levels in the hypercholesterolemic subjects. Lipids Health Dis 2012; 11:9. [PMID: 22243772 PMCID: PMC3271972 DOI: 10.1186/1476-511x-11-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 01/13/2012] [Indexed: 11/24/2022] Open
Abstract
Background Acyl-CoA:cholesterol acyltransferase (ACAT) is a key enzyme in cellular cholesterol homeostasis and in atherosclerosis. The cellular cholesterol efflux correlated with serum high-density lipoprotein cholesterol (HDL-C) concentrations has shown to be impaired in hyperlipidemic mice. The present study was carried out to clarify the association of ACAT-1 rs1044925 single nucleotide polymorphism (SNP) and serum lipid levels in the hyperlipidemic subjects. Methods A total of 821 unrelated subjects (hyperlipidemia, 476; normolipidemia, 345) aged 15-80 were included in the study. Genotyping of the ACAT-1 rs1044925 SNP was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing. Results There was no significant difference in the genotypic and allelic frequencies of ACAT-1 rs1044925 SNP between the normolipidemic and hyperlipidemic subjects. The levels of total cholesterol (TC), HDL-C and apolipoprotein (Apo) AI in hyperlipidemic subjects were different between the AA and AC/CC genotypes in male but not in female (P < 0.05-0.01), the C allele carriers had higher serum TC, HDL-C and ApoAI levels than the C allele noncarriers. The association of genotypes and serum HDL-C and ApoAI levels in hyperlipidemia was found mainly in the male subjects with hypercholesterolemia but not in those with hypertriglyceridemia. There were no significant differences in serum lipid levels between the AA and AC/CC genotypes in the normolipidemic subjects. Conclusions The present study shows that the C allele carriers of ACAT-1 rs1044925 SNP in male hyperlipidemic subjects had higher serum TC, HDL-C and ApoAI levels than the C allele noncarriers. There is a sex (male)-specific association of ACAT-1 rs1044925 SNP and serum HDL-C and ApoAI levels in the hypercholesterolemic subjects.
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Affiliation(s)
- Dong-Feng Wu
- Department of Cardiology, Institute of Cardiovascular Diseases, the First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, People's Republic of China
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Isoform-specific inhibitors of ACATs: recent advances and promising developments. Future Med Chem 2011; 3:2039-61. [DOI: 10.4155/fmc.11.158] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Acyl-CoA:cholesterol acyltransferase (ACAT) is a promising therapeutic target for cardiovascular diseases. Although a number of synthetic ACAT inhibitors have been developed, they have failed to show efficacy in clinical trials. Now, the presence of two ACAT isoforms with distinct functions, ACAT1 and ACAT2, has been discovered. Thus, the selectivity of ACAT inhibitors toward the two isoforms is important for their development as novel anti-atherosclerotic agents. The selectivity study indicated that fungal pyripyropene A (PPPA) is only an ACAT2-specific inhibitor. Furthermore, PPPA proved orally active in atherogenic mouse models, indicating it possessed cholesterol-lowering and atheroprotective activities. Certain PPPA derivatives, semi-synthetically prepared, possessed more potent and selective in vitro activity than PPPA against ACAT2. This review covers these studies and describes the future prospects of ACAT2-specific inhibitors.
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Wu DF, Yin RX, Aung LHH, Hu XJ, Cao XL, Miao L, Li Q, Yan TT, Wu JZ, Pan SL. Polymorphism of rs1044925 in the acyl-CoA:cholesterol acyltransferase-1 gene and serum lipid levels in the Guangxi Bai Ku Yao and Han populations. Lipids Health Dis 2010; 9:139. [PMID: 21143839 PMCID: PMC3022751 DOI: 10.1186/1476-511x-9-139] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 12/08/2010] [Indexed: 11/22/2022] Open
Abstract
Background The association of rs1044925 polymorphism in the acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) gene and serum lipid profiles is not well known in different ethnic groups. Bai Ku Yao is a special subgroup of the Yao minority in China. The present study was carried out to clarify the association of rs1044925 polymorphism in the ACAT-1 gene and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations. Methods A total of 626 subjects of Bai Ku Yao and 624 participants of Han Chinese were randomly selected from our previous stratified randomized cluster samples. Genotyping of rs1044925 polymorphism in the ACAT-1 gene was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing. Results The levels of serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (Apo) AI and ApoB were lower in Bai Ku Yao than in Han (P < 0.01 for all). The frequency of A and C alleles was 79.0% and 21.0% in Bai Ku Yao, and 87.3% and 12.7% in Han (P < 0.001); respectively. The frequency of AA, AC and CC genotypes was 63.2%, 31.4% and 5.2% in Bai Ku Yao, and 75.6%, 23.2% and 1.1% in Han (P < 0.001); respectively. The levels of TC, LDL-C and ApoB in Bai Ku Yao but not in Han were different between the AA and AC/CC genotypes in females but not in males (P < 0.05 for all). The C allele carriers had lower serum TC, LDL-C and ApoB levels as compared with the C allele noncarriers. The levels of TC, LDL-C and ApoB in Bai Ku Yao but not in Han were correlated with genotypes in females but not in males (P < 0.05 for all). Serum lipid parameters were also correlated with sex, age, body mass index, alcohol consumption, and blood pressure in both ethnic groups (P < 0.05-0.001). Conclusions These results suggest that the polymorphism of rs1044925 in the ACAT-1 gene is mainly associated with female serum TC, LDL-C and ApoB levels in the Bai Ku Yao population. The C allele carriers had lower serum TC, LDL-C and ApoB levels than the C allele noncarriers.
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Affiliation(s)
- Dong-Feng Wu
- Department of Cardiology, Institute of Cardiovascular Diseases, the First Affiliated Hospital, Guangxi Medical University, 22 Shuangyong Road, Nanning 530021, Guangxi, China
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McFie PJ, Stone SL, Banman SL, Stone SJ. Topological orientation of acyl-CoA:diacylglycerol acyltransferase-1 (DGAT1) and identification of a putative active site histidine and the role of the n terminus in dimer/tetramer formation. J Biol Chem 2010; 285:37377-87. [PMID: 20876538 DOI: 10.1074/jbc.m110.163691] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acyl CoA:diacylglycerol acyltransferase (DGAT) is an integral membrane protein of the endoplasmic reticulum that catalyzes the synthesis of triacylglycerols. Two DGAT enzymes have been identified (DGAT1 and DGAT2) with unique roles in lipid metabolism. DGAT1 is a multifunctional acyltransferase capable of synthesizing diacylglycerol, retinyl, and wax esters in addition to triacylglycerol. Here, we report the membrane topology for murine DGAT1 using protease protections assays and indirect immunofluorescence in conjunction with selective permeabilization of cellular membranes. Topology models based on prediction algorithms suggested that DGAT1 had eight transmembrane domains. In contrast, our data indicate that DGAT1 has three transmembrane domains with the N terminus oriented toward the cytosol. The C-terminal region of DGAT1, which accounts for ∼50% of the protein, is present in the endoplasmic reticulum lumen and contains a highly conserved histidine residue (His-426) that may be part of the active site. Mutagenesis of His-426 to alanine impaired the ability of DGAT1 to synthesize triacylglycerols as well as retinyl and wax esters in an in vitro acyltransferase assay. Finally, we show that the N-terminal domain of DGAT1 is not required for the catalytic activity of DGAT1 but, instead, may be involved in regulating enzyme activity and dimer/tetramer formation.
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Affiliation(s)
- Pamela J McFie
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
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Buglino JA, Resh MD. Identification of conserved regions and residues within Hedgehog acyltransferase critical for palmitoylation of Sonic Hedgehog. PLoS One 2010; 5:e11195. [PMID: 20585641 PMCID: PMC2890405 DOI: 10.1371/journal.pone.0011195] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 05/27/2010] [Indexed: 11/18/2022] Open
Abstract
Background Sonic hedgehog (Shh) is a palmitoylated protein that plays key roles in mammalian development and human cancers. Palmitoylation of Shh is required for effective long and short range Shh-mediated signaling. Attachment of palmitate to Shh is catalyzed by Hedgehog acyltransferase (Hhat), a member of the membrane bound O-acyl transferase (MBOAT) family of multipass membrane proteins. The extremely hydrophobic composition of MBOAT proteins has limited their biochemical characterization. Except for mutagenesis of two conserved residues, there has been no structure-function analysis of Hhat, and the regions of the protein required for Shh palmitoylation are unknown. Methodology/Principal Findings Here we undertake a systematic approach to identify residues within Hhat that are required for protein stability and/or enzymatic activity. We also identify a second, novel MBOAT homology region (residues 196–234) that is required for Hhat activity. In total, ten deletion mutants and eleven point mutants were generated and analyzed. Truncations at the N- and C-termini of Hhat yielded inactive proteins with reduced stability. Four Hhat mutants with deletions within predicted loop regions and five point mutants retained stability but lost palmitoylation activity. We purified two point mutants, W378A and H379A, with defective Hhat activity. Kinetic analyses revealed alterations in apparent Km and Vmax for Shh and/or palmitoyl CoA, changes that likely explain the catalytic defects observed for these mutants. Conclusions/Significance This study has pinpointed specific regions and multiple residues that regulate Hhat stability and catalysis. Our findings should be applicable to other MBOAT proteins that mediate lipid modification of Wnt proteins and ghrelin, and should serve as a model for understanding how secreted morphogens are modified by palmitoyl acyltransferases.
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Affiliation(s)
- John A. Buglino
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
- Graduate Program in Biochemistry, Cell and Molecular Biology, Weill Graduate School of Medical Sciences, Cornell University, New York, New York, United States of America
| | - Marilyn D. Resh
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America
- Graduate Program in Biochemistry, Cell and Molecular Biology, Weill Graduate School of Medical Sciences, Cornell University, New York, New York, United States of America
- * E-mail:
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Bhattacharyya R, Kovacs DM. ACAT inhibition and amyloid beta reduction. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:960-5. [PMID: 20398792 DOI: 10.1016/j.bbalip.2010.04.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 04/01/2010] [Accepted: 04/02/2010] [Indexed: 12/26/2022]
Abstract
Alzheimer's disease (AD) is a devastating neurodegenerative disorder. Accumulation and deposition of the beta-amyloid (Abeta) peptide generated from its larger amyloid precursor protein (APP) is one of the pathophysiological hallmarks of AD. Intracellular cholesterol was shown to regulate Abeta production. Recent genetic and biochemical studies indicate that not only the amount, but also the distribution of intracellular cholesterol is critical to regulate Abeta generation. Acyl-coenzyme A: cholesterol acyl-transferase (ACAT) is a family of enzymes that regulates the cellular distribution of cholesterol by converting membrane cholesterol into hydrophobic cholesteryl esters for cholesterol storage and transport. Using pharmacological inhibitors and transgenic animal models, we and others have identified ACAT1 as a potential therapeutic target to lower Abeta generation and accumulation. Here we discuss data focusing on ACAT inhibition as an effective strategy for the prevention and treatment of AD.
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Affiliation(s)
- Raja Bhattacharyya
- Neurobiology of Disease Laboratory, Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Diseases (MIND), Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
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Rutledge AC, Su Q, Adeli K. Apolipoprotein B100 biogenesis: a complex array of intracellular mechanisms regulating folding, stability, and lipoprotein assemblyThis paper is one of a selection of papers published in this special issue entitled “Canadian Society of Biochemistry, Molecular & Cellular Biology 52nd Annual Meeting — Protein Folding: Principles and Diseases” and has undergone the Journal's usual peer review process. Biochem Cell Biol 2010; 88:251-67. [DOI: 10.1139/o09-168] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Apolipoprotein B100 (apoB) is a large amphipathic lipid-binding protein that is synthesized by hepatocytes and used to assemble and stabilize very low density lipoproteins (VLDL). It may have been derived through evolution from other lipid-associating proteins such as microsomal triglyceride transfer protein or vitellogenin. The correct folding of apoB requires assistance from chaperone proteins in co-translational lipidation, disulfide bond formation, and glycosylation. Any impairment in these processes results in co-translational targeting of the misfolded apoB molecule for proteasomal degradation. In fact, most of the regulation of apoB production is mediated by intracellular degradation. ApoB that misfolds post-translationally, perhaps as a result of oxidative stress, may be eliminated through autophagy. This review focuses on the proposed pentapartite domain structure of apoB, the role that each domain plays in the binding of lipid species and regulation of apoB synthesis, and the process of VLDL assembly. The factors involved in the recognition, ubiquitination, and proteasomal delivery of defective apoB molecules are also discussed.
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Affiliation(s)
- Angela C. Rutledge
- Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Room 3652, 555 University Ave., Toronto, ON M5G 1X8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, Room 6243, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Qiaozhu Su
- Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Room 3652, 555 University Ave., Toronto, ON M5G 1X8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, Room 6243, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Khosrow Adeli
- Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Room 3652, 555 University Ave., Toronto, ON M5G 1X8, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, Room 6243, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
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Skinner JR, Shew TM, Schwartz DM, Tzekov A, Lepus CM, Abumrad NA, Wolins NE. Diacylglycerol enrichment of endoplasmic reticulum or lipid droplets recruits perilipin 3/TIP47 during lipid storage and mobilization. J Biol Chem 2009; 284:30941-8. [PMID: 19748893 PMCID: PMC2781494 DOI: 10.1074/jbc.m109.013995] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 09/01/2009] [Indexed: 12/21/2022] Open
Abstract
Fatty acid-induced triacylglycerol synthesis produces triacylglycerol droplets with a protein coat that includes perilipin 3/TIP47 and perilipin 4/S3-12. This study addresses the following two questions. Where do lipid droplets emerge, and how are their coat proteins recruited? We show that perilipin 3- and perilipin 4-coated lipid droplets emerge along the endoplasmic reticulum (ER). Blocking membrane trafficking with AlF(4)(-) during fatty acid-induced triacylglycerol synthesis drove perilipin 3 to the tubular ER. Forskolin, which like AlF(4)(-) activates adenylate cyclase, did not redistribute perilipin 3, but when added together with AlF(4)(-) perilipin 3 was recruited to lipid droplets rather than the ER. Thus inhibiting trafficking with AlF(4)(-) redistributed perilipin 3 differently under conditions of triacylglycerol synthesis (fatty acid addition) versus hydrolysis (forskolin) suggesting a shared acylglycerol-mediated mechanism. We tested whether diacylglycerol (DG), the immediate precursor of triacylglycerol and its first hydrolytic product, affects the distribution of perilipin 3. Stabilizing DG with the DG lipase inhibitor RHC80267 enhanced the perilipin 3 recruited to lipid droplets and raised DG levels in this fraction. Treating cells with a membrane-permeable DG recruited perilipin 3 to the ER. Stabilizing DG, by blocking its hydrolysis with RHC80267 or its acylation with triacsin C, enhanced recruitment of perilipin 3 to the ER. Expressing the ER enzyme DGAT1, which removes DG by converting it to triacylglycerol, attenuated perilipin 3 DG-induced ER recruitment. Membrane-permeable DG also drove perilipin 4 and 5 onto the ER. Together the data suggest that these lipid droplet proteins are recruited to DG-enriched membranes thereby linking lipid coat proteins to the metabolic state of the cell.
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Affiliation(s)
| | | | | | | | | | - Nada A. Abumrad
- From the Center for Human Nutrition and
- Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110
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Doolittle MH, Neher SB, Ben-Zeev O, Ling-Liao J, Gallagher CM, Hosseini M, Yin F, Wong H, Walter P, Péterfy M. Lipase maturation factor LMF1, membrane topology and interaction with lipase proteins in the endoplasmic reticulum. J Biol Chem 2009; 284:33623-33. [PMID: 19783858 DOI: 10.1074/jbc.m109.049395] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipase maturation factor 1 (LMF1) is predicted to be a polytopic protein localized to the endoplasmic reticulum (ER) membrane. It functions in the post-translational attainment of enzyme activity for both lipoprotein lipase and hepatic lipase. By using transmembrane prediction methods in mouse and human orthologs, models of LMF1 topology were constructed and tested experimentally. Employing a tagging strategy that used insertion of ectopic glycan attachment sites and terminal fusions of green fluorescent protein, we established a five-transmembrane model, thus dividing LMF1 into six domains. Three domains were found to face the cytoplasm (the amino-terminal domain and loops B and D), and the other half was oriented to the ER lumen (loops A and C and the carboxyl-terminal domain). This representative model shows the arrangement of an evolutionarily conserved domain within LMF1 (DUF1222) that is essential to lipase maturation. DUF1222 comprises four of the six domains, with the two largest ones facing the ER lumen. We showed for the first time, using several naturally occurring variants featuring DUF1222 truncations, that Lmf1 interacts physically with lipoprotein lipase and hepatic lipase and localizes the lipase interaction site to loop C within DUF1222. We discuss the implication of our results with regard to lipase maturation and DUF1222 domain structure.
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Affiliation(s)
- Mark H Doolittle
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA.
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Igarashi M, Osuga JI, Isshiki M, Sekiya M, Okazaki H, Takase S, Takanashi M, Ohta K, Kumagai M, Nishi M, Fujita T, Nagai R, Kadowaki T, Ishibashi S. Targeting of neutral cholesterol ester hydrolase to the endoplasmic reticulum via its N-terminal sequence. J Lipid Res 2009; 51:274-85. [PMID: 19592704 DOI: 10.1194/jlr.m900201-jlr200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Neutral cholesterol ester hydrolase (NCEH) accounts for a large part of the nCEH activity in macrophage foam cells, a hallmark of atherosclerosis, but its subcellular localization and structure-function relationship are unknown. Here, we determined subcellular localization, glycosylation, and nCEH activity of a series of NCEH mutants expressed in macrophages. NCEH is a single-membrane-spanning type II membrane protein comprising three domains: N-terminal, catalytic, and lipid-binding domains. The N-terminal domain serves as a type II signal anchor sequence to recruit NCEH to the endoplasmic reticulum (ER) with its catalytic domain within the lumen. All of the putative N-linked glycosylation sites (Asn(270), Asn(367), and Asn(389)) of NCEH are glycosylated. Glycosylation at Asn(270), which is located closest to the catalytic serine motif, is important for the enzymatic activity. Cholesterol loading by incubation with acetyl-LDL does not change the ER localization of NCEH. In conclusion, NCEH is targeted to the ER of macrophages, where it hydrolyzes CE to deliver cholesterol for efflux out of the cells.
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Affiliation(s)
- Masaki Igarashi
- Department of Metabolic Diseases, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
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Abstract
The enzymes acyl-coenzyme A (CoA):cholesterol acyltransferases (ACATs) are membrane-bound proteins that utilize long-chain fatty acyl-CoA and cholesterol as substrates to form cholesteryl esters. In mammals, two isoenzymes, ACAT1 and ACAT2, encoded by two different genes, exist. ACATs play important roles in cellular cholesterol homeostasis in various tissues. This chapter summarizes the current knowledge on ACAT-related research in two areas: 1) ACAT genes and proteins and 2) ACAT enzymes as drug targets for atherosclerosis and for Alzheimer's disease.
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Affiliation(s)
- Ta-Yuan Chang
- Department of Biochemistry, Dartmouth Medical School, 1 Rope Ferry Rd., Hanover, NH 03755-1404, USA.
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Antalis CJ, Arnold T, Lee B, Buhman KK, Siddiqui RA. Docosahexaenoic acid is a substrate for ACAT1 and inhibits cholesteryl ester formation from oleic acid in MCF-10A cells. Prostaglandins Leukot Essent Fatty Acids 2009; 80:165-71. [PMID: 19217763 DOI: 10.1016/j.plefa.2009.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 11/20/2008] [Accepted: 01/03/2009] [Indexed: 01/23/2023]
Abstract
MCF-10A breast epithelial cells treated with docosahexaenoic acid (DHA) or oleic acid (OA) accumulated cytoplasmic lipid droplets containing both triacylglycerol and cholesteryl esters (CE). Interestingly, total CE mass was reduced in cells treated with DHA compared to cells treated with OA, and the CEs were rich in n-3 fatty acids. Thus, we hypothesized that DHA may be, in addition to a substrate, an inhibitor of cholesterol esterification in MCF-10A cells. We determined that the primary isoform of acyl-CoA: cholesterol acyltransferase expressed in MCF-10A cells is ACAT1. We investigated CE formation with DHA, OA, and the combination in intact cells and isolated microsomes. In both cells and microsomes, the rate of CE formation was faster and more CE was formed with OA compared to DHA. DHA substantially reduced CE formation when given in combination with OA. These data suggest for the first time that DHA can act as a substrate for ACAT1. In the manner of a poor substrate, DHA also inhibited the activity of ACAT1, a universally expressed enzyme involved in intracellular cholesterol homeostasis, in a cell type that does not secrete lipids or express ACAT2.
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Affiliation(s)
- Caryl J Antalis
- Cellular Biochemistry Laboratory, Methodist Research Institute, 1800 N. Capitol Avenue, Suite E504, Indianapolis, IN 46202, USA.
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43
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Das A, Davis MA, Rudel LL. Identification of putative active site residues of ACAT enzymes. J Lipid Res 2008; 49:1770-81. [PMID: 18480028 PMCID: PMC2444009 DOI: 10.1194/jlr.m800131-jlr200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 04/22/2008] [Indexed: 11/20/2022] Open
Abstract
In this report, we sought to determine the putative active site residues of ACAT enzymes. For experimental purposes, a particular region of the C-terminal end of the ACAT protein was selected as the putative active site domain due to its high degree of sequence conservation from yeast to humans. Because ACAT enzymes have an intrinsic thioesterase activity, we hypothesized that by analogy with the thioesterase domain of fatty acid synthase, the active site of ACAT enzymes may comprise a catalytic triad of ser-his-asp (S-H-D) amino acid residues. Mutagenesis studies revealed that in ACAT1, S456, H460, and D400 were essential for activity. In ACAT2, H438 was required for enzymatic activity. However, mutation of D378 destabilized the enzyme. Surprisingly, we were unable to identify any S mutations of ACAT2 that abolished catalytic activity. Moreover, ACAT2 was insensitive to serine-modifying reagents, whereas ACAT1 was not. Further studies indicated that tyrosine residues may be important for ACAT activity. Mutational analysis showed that the tyrosine residue of the highly conserved FYXDWWN motif was important for ACAT activity. Furthermore, Y518 was necessary for ACAT1 activity, whereas the analogous residue in ACAT2, Y496, was not. The available data suggest that the amino acid requirement for ACAT activity may be different for the two ACAT isozymes.
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Affiliation(s)
- Akash Das
- Department of Biochemistry, Section on Lipid Sciences, Wake Forest University School of Medicine, Winston Salem, NC 27157-1040
| | - Matthew A. Davis
- Department of Pathology, Section on Lipid Sciences, Wake Forest University School of Medicine, Winston Salem, NC 27157-1040
| | - Lawrence L. Rudel
- Department of Biochemistry, Section on Lipid Sciences, Wake Forest University School of Medicine, Winston Salem, NC 27157-1040
- Department of Pathology, Section on Lipid Sciences, Wake Forest University School of Medicine, Winston Salem, NC 27157-1040
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44
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Iqbal J, Rudel LL, Hussain MM. Microsomal triglyceride transfer protein enhances cellular cholesteryl esterification by relieving product inhibition. J Biol Chem 2008; 283:19967-80. [PMID: 18502767 DOI: 10.1074/jbc.m800398200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cholesteryl ester synthesis by the acyl-CoA:cholesterol acyltransferase enzymes ACAT1 and ACAT2 is, in part, a cellular homeostatic mechanism to avoid toxicity associated with high free cholesterol levels. In hepatocytes and enterocytes, cholesteryl esters are secreted as part of apoB lipoproteins, the assembly of which is critically dependent on microsomal triglyceride transfer protein (MTP). Conditional genetic ablation of MTP reduces cholesteryl esters and enhances free cholesterol in the liver and intestine without diminishing ACAT1 and ACAT2 mRNA levels. As expected, increases in hepatic free cholesterol are associated with decreases in 3-hydroxy-3-methylglutaryl-CoA reductase and increases in ATP-binding cassette transporter 1 mRNA levels. Chemical inhibition of MTP also decreases esterification of cholesterol in Caco-2 and HepG2 cells. Conversely, coexpression of MTP and apoB in AC29 cells stably transfected with ACAT1 and ACAT2 increases cholesteryl ester synthesis. Liver and enterocyte microsomes from MTP-deficient animals synthesize lesser amounts of cholesteryl esters in vitro, but addition of purified MTP and low density lipoprotein corrects this deficiency. Enrichment of microsomes with cholesteryl esters also inhibits cholesterol ester synthesis. Thus, MTP enhances cellular cholesterol esterification by removing cholesteryl esters from their site of synthesis and depositing them into nascent apoB lipoproteins. Therefore, MTP plays a novel role in regulating cholesteryl ester biosynthesis in cells that produce lipoproteins. We speculate that non-lipoprotein-producing cells may use different mechanisms to alleviate product inhibition and modulate cholesteryl ester biosynthesis.
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Affiliation(s)
- Jahangir Iqbal
- Department of Anatomy and Cell Biology and Pediatrics, State University of New York Downstate Medical Center, Brooklyn, NY 11203, USA
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45
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Das A, Davis MA, Tomoda H, Omura S, Rudel LL. Identification of the interaction site within acyl-CoA:cholesterol acyltransferase 2 for the isoform-specific inhibitor pyripyropene A. J Biol Chem 2008; 283:10453-60. [PMID: 18285335 PMCID: PMC2447654 DOI: 10.1074/jbc.m709460200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 02/15/2008] [Indexed: 11/06/2022] Open
Abstract
Targeted deletion of acyl-CoA:cholesterol acyltransferase 2 (ACAT2) (A2), especially in the liver, protects hyperlipidemic mice from diet-induced hypercholesterolemia and atherosclerosis, whereas the deletion of ACAT1 (A1) is not as effective, suggesting ACAT2 may be the more appropriate target for treatment of atherosclerosis. Among the numerous ACAT inhibitors known, pyripyropene A (PPPA) is the only compound that has high selectivity (>2000-fold) for inhibition of ACAT2 compared with ACAT1. In the present study we sought to determine the PPPA interaction site of ACAT2. To achieve this goal we made several chimeric proteins where parts of ACAT2 were replaced by the analogous region of ACAT1. Differences in the amino acid sequence and the membrane topology were utilized to design the chimeras. Among chimeras, A2:1-428/A1:444-550 had 50% reduced PPPA selectivity, whereas C-terminal-truncated ACAT2 mutant A2:1-504 (C-terminal last 22 amino acids were deleted) remained selectively inhibited, indicating the PPPA-sensitive site is located within a region between amino acids 440 and 504. Three additional chimeras within this region helped narrow down the PPPA-sensitive site to a region containing amino acids 480-504, representing the fifth putative transmembrane domain of ACAT2. Subsequently, for this region we made single amino acid mutants where each amino acid in ACAT2 was individually changed to its ACAT1 counterpart. Mutation of Q492L, V493L, S494A resulted in only 30, 50, and 70% inhibition of the activity by PPPA, respectively (as opposed to greater than 95% with the wild type enzyme), suggesting these three residues are responsible for the selective inhibition by PPPA of ACAT2. Additionally, we found that PPPA non-covalently interacts with ACAT2 apparently without altering the oligomeric structure of the protein. The present study provides the first evidence for a unique motif in ACAT2 that can be utilized for making an ACAT2-specific drug.
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Affiliation(s)
- Akash Das
- Department of Biochemistry, Section on Lipid Science, Wake Forest University School of Medicine, Winston Salem, North Carolina 27157-1040, USA
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Yu K, Li R, Hatanaka T, Hildebrand D. Cloning and functional analysis of two type 1 diacylglycerol acyltransferases from Vernonia galamensis. PHYTOCHEMISTRY 2008; 69:1119-27. [PMID: 18179805 DOI: 10.1016/j.phytochem.2007.11.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Revised: 11/17/2007] [Accepted: 11/26/2007] [Indexed: 05/12/2023]
Abstract
Vernonia galamensis accumulates vernolic acid (cis-12-epoxyoctadeca-cis-9-enoic acid) as the major fatty acid in its seed oil. Such epoxy fatty acids are useful in a number of industrial applications. Successful genetic engineering of commercial oilseed crops to produce high levels of vernolic acid depends on a better understanding of the source plant enzymes for vernolic acid accumulation. Developing V. galamensis seed microsome assays demonstrate that diacylglycerol acyltransferase (DGAT), an enzyme for the final step of triacylglycerol synthesis, has a strong substrate preference for vernolic acid bearing substrates including acyl-CoA and diacylglycerol. There are two classes of DGATs known as DGAT1 and DGAT2. Here we report on the isolation, characterization, and functional analysis of two DGAT1 cDNAs from V. galamensis (VgDGAT1a and VgDGAT1b). VgDGAT1a and VgDGAT1b are expressed in all plant tissues examined with highest expression in developing seeds. Enzymatic assays using isolated microsomes from transformed yeast show that VgDGAT1a and VgDGAT1b have the same DGAT activity levels and substrate specificities. Oleoyl-CoA and sn-1,2-dioleoylglycerol are preferred substrates over vernoloyl-CoA and sn-1,2-divernoloylglycerol. This data indicates that the two VgDGAT1s are functional, but not likely to be responsible for the selective accumulation of vernolic acid in V. galamensis seed oil.
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Affiliation(s)
- Keshun Yu
- Department of Plant and Soil Science, University of Kentucky, 1405 Veterans Drive, Lexington, KY 40546-0091, USA
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47
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Fujimoto Y, Yonemura T, Sakuma S. Stearic acid potently modulates the activity of cyclooxygenase-1, but not cyclooxygenase-2, in the form of its CoA ester. Prostaglandins Leukot Essent Fatty Acids 2008; 78:81-4. [PMID: 18083017 DOI: 10.1016/j.plefa.2007.10.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 08/03/2007] [Accepted: 10/31/2007] [Indexed: 10/22/2022]
Abstract
The effects of palmitic acid (PA), stearic acid (SA) and oleic acid (OA), and their respective CoA esters, PA-CoA, SA-CoA and OA-CoA, on the activities of cyclooxygenase (COX)-1 and -2 were examined. Ten units of purified COX-1 or -2 were preincubated with drugs in the presence of hematin (0.1 microM) and phenol (2 mM) as cofactors for 10 min at 37 degrees C, and then incubated with 100 microM arachidonic acid for 2 min at 37 degrees C. The amounts of prostaglandins formed were measured by HPLC. PA, SA and OA had no effect on the COX-1 and -2 activities, but their respective CoA esters, PA-CoA, SA-CoA and OA-CoA, suppressed COX-1 activity with no significant effect on COX-2 activity. The inhibitory effect of SA-CoA was much stronger than that of PA-CoA and OA-CoA. These results suggest that SA has the potential to inhibit COX-1 activity, but not COX-2 activity, in the form of their CoA ester.
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Affiliation(s)
- Yohko Fujimoto
- Department of Physiological Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka, Japan.
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Tomoda H, Omura S. Potential therapeutics for obesity and atherosclerosis: Inhibitors of neutral lipid metabolism from microorganisms. Pharmacol Ther 2007; 115:375-89. [PMID: 17614133 DOI: 10.1016/j.pharmthera.2007.05.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Accepted: 05/16/2007] [Indexed: 11/24/2022]
Abstract
Diacylglycerol acyltransferase (DGAT) and acyl-CoA: cholesterol acyltransferase (ACAT) are the enzymes that catalyze the final reactions of triacylgycerol (TG) and cholesteryl ester (CE) synthesis, and accumulation of TG and CE in adipocytes and arteries causes obesity and atherosclerosis, respectively. Therefore, DGAT and ACAT have been viewed as potential therapeutic targets for these diseases. From the screening program for DGAT inhibitors, new compounds were discovered from fungal and plant extracts, and are expected to provide leads for drug development. From the screening programs for ACAT inhibitors and lipid droplet synthesis inhibitors, new compounds with chemical structures different from those of known synthetic inhibitors were discovered from the cultures of fungal and actinomycete strains. Among them, fungal beauveriolide III rather selectively inhibited ACAT1 isozyme, while fungal pyripyropene A was found to be a highly selective inhibitor of ACAT2 isozyme. Both inhibitors proved orally active in in vivo models. Furthermore, a library of beauveriolide and pyripyropene analogs was prepared by combinatorial and semisynthetic methods, respectively. The future prospects of these inhibitors are discussed.
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Temel RE, Hou L, Rudel LL, Shelness GS. ACAT2 stimulates cholesteryl ester secretion in apoB-containing lipoproteins. J Lipid Res 2007; 48:1618-27. [PMID: 17438337 DOI: 10.1194/jlr.m700109-jlr200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies in nonhuman primates revealed a striking positive correlation between liver cholesteryl ester (CE) secretion rate and the development of coronary artery atherosclerosis. CE incorporated into hepatic VLDL is necessarily synthesized by ACAT2, the cholesterol-esterifying enzyme in hepatocytes. We tested the hypothesis that the level of ACAT2 expression, in concert with cellular cholesterol availability, affects the CE content of apolipoprotein B (apoB)-containing lipoproteins. In a model system of lipoprotein secretion using COS cells cotransfected with microsomal triglyceride transfer protein and truncated forms of apoB, ACAT2 expression resulted in a 3-fold increase in microsomal ACAT activity and a 4-fold increase in the radiolabeled CE content of apoB-lipoproteins. After cholesterol-cyclodextrin (Chol-CD) treatment, CE secretion was increased by 27-fold in ACAT2-transfected cells but by only 7-fold in control cells. Chol-CD treatment also caused the percentage of CE in the apoB-lipoproteins to increase from 3% to 33% in control cells and from 16% to 54% in ACAT2-transfected cells. In addition, ACAT2-transfected cells secreted 3-fold more apoB than control cells. These results indicate that under all conditions of cellular cholesterol availability tested, the relative level of ACAT2 expression affects the CE content and, hence, the potential atherogenicity, of nascent apoB-containing lipoproteins.
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Affiliation(s)
- Ryan E Temel
- Department of Pathology, Section on Lipid Sciences, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
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50
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Ohshiro T, Rudel LL, Omura S, Tomoda H. Selectivity of microbial acyl-CoA: cholesterol acyltransferase inhibitors toward isozymes. J Antibiot (Tokyo) 2007; 60:43-51. [PMID: 17390588 DOI: 10.1038/ja.2007.6] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The selectivity of microbial inhibitors of acyl-CoA: cholesterol acyltransferase (ACAT) toward the two isozymes, ACAT1 and ACAT2, was assessed in cell-based assays. Purpactin A (IC50 values of ACAT1 vs. IC50 values of ACAT2; 2.5 microM vs. 1.5 microM), terpendole C (10 microM vs. 10 microM), glisoprenin A (4.3 microM vs. 10 microM), spylidone (25 microM vs. 5.0 microM) and synthetic CL-283,546 (0.1 microM vs. 0.09 microM) inhibited ACAT1 and ACAT2 to similar extents. Beauveriolides I (0.6 microM vs. 20 microM) and III (0.9 microM vs. >20 microM) inhibited ACAT1 rather selectively, while pyripyropenes A (>80 microM vs. 0.07 microM), B (48 microM vs. 2.0 microM), C (32 microM vs. 0.36 microM) and D (38 microM vs. 1.5 microM) showed selective inhibition against ACAT2. In particular, pyripyropene A was found to be the most selective ACAT2 inhibitor with a selective index of more than 1,000.
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Affiliation(s)
- Taichi Ohshiro
- Kitasato Institute for Life Sciences, Graduate School of Infection Control Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
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