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Moll TO, Klemek ML, Farber SA. Directly Measuring Atherogenic Lipoprotein Kinetics in Zebrafish with the Photoconvertible LipoTimer Reporter. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.29.596423. [PMID: 38853962 PMCID: PMC11160697 DOI: 10.1101/2024.05.29.596423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Lipoprotein kinetics are a crucial factor in understanding lipoprotein metabolism since a prolonged time in circulation can contribute to the atherogenic character of apolipoprotein-B (ApoB)-containing lipoproteins (B-lps). Here, we report a method to directly measure lipoprotein kinetics in live developing animals. We developed a zebrafish geneticly encoded reporter, LipoTimer, in which endogenous ApoBb.1 is fused to the photoconvertible fluorophore Dendra2 which shift its emission profile from green to red upon UV exposure. By quantifying the red population of ApoB-Dendra2 over time, we found that B-lp turnover in wild-type larvae becomes faster as development proceeds. Mutants with impaired B-lp uptake or lipolysis present with increased B-lp levels and half-life. In contrast, mutants with impaired B-lp triglyceride loading display slightly fewer and smaller-B-lps, which have a significantly shorter B-lp half-life. Further, we showed that chronic high-cholesterol feeding is associated with a longer B-lp half-life in wild-type juveniles but does not lead to changes in B-lp half-life in lipolysis deficient apoC2 mutants. These data support the hypothesis that B-lp lipolysis is suppressed by the flood of intestinal-derived B-lps that follow a high-fat meal.
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Affiliation(s)
- Tabea O.C. Moll
- Johns Hopkins University, Baltimore, Maryland, United States of America
| | | | - Steven A. Farber
- Johns Hopkins University, Baltimore, Maryland, United States of America
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2
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Sanyasi C, Balakrishnan SS, Chinnasamy T, Venugopalan N, Kandavelu P, Batra-Safferling R, Muthuvel SK. Insights on the dynamic behavior of protein disulfide isomerase in the solution environment through the SAXS technique. In Silico Pharmacol 2024; 12:23. [PMID: 38584776 PMCID: PMC10997565 DOI: 10.1007/s40203-024-00198-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 02/17/2024] [Indexed: 04/09/2024] Open
Abstract
The dynamic behavior of Protein Disulfide Isomerase (PDI) in an aqueous solution environment under physiologically active pH has been experimentally verified in this study using Small Angle X-ray Scattering (SAXS) technique. The structural mechanism of dimerization for full-length PDI molecules and co-complex with two renowned substrates has been comprehensively discussed. The structure models obtained from the SAXS data of PDI purified from bovine liver display behavior duality between unaccompanied-enzyme and after engaged with substrates. The analysis of SAXS data revealed that PDI exists as a homo-dimer in the solution environment, and substrate induction provoked its segregation into monomer to enable the enzyme to interact systematically with incoming clients. Supplementary Information The online version contains supplementary material available at 10.1007/s40203-024-00198-0.
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Affiliation(s)
- Chandrasekar Sanyasi
- Department of Bioinformatics, School of Life Sciences, Pondicherry University, Pondicherry, 605014 India
| | - Susmida Seni Balakrishnan
- Department of Bioinformatics, School of Life Sciences, Pondicherry University, Pondicherry, 605014 India
| | - Thirunavukkarasu Chinnasamy
- Department of Biochemistry and Molecular Biology, School of Life Sciences, Pondicherry University, Pondicherry, 605014 India
| | - Nagarajan Venugopalan
- GMCA Structural Biology Facility, X-Ray Science Division, Argonne National Laboratory, Argonne, IL USA
| | - Palani Kandavelu
- SER-CAT and The Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30601 USA
| | - Renu Batra-Safferling
- Institute of Complex Systems (ICS-6: Structural Biochemistry), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Suresh Kumar Muthuvel
- Department of Bioinformatics, School of Life Sciences, Pondicherry University, Pondicherry, 605014 India
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3
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Apolipoprotein B and Cardiovascular Disease: Biomarker and Potential Therapeutic Target. Metabolites 2021; 11:metabo11100690. [PMID: 34677405 PMCID: PMC8540246 DOI: 10.3390/metabo11100690] [Citation(s) in RCA: 84] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/04/2021] [Accepted: 10/06/2021] [Indexed: 12/19/2022] Open
Abstract
Apolipoprotein (apo) B, the critical structural protein of the atherogenic lipoproteins, has two major isoforms: apoB48 and apoB100. ApoB48 is found in chylomicrons and chylomicron remnants with one apoB48 molecule per chylomicron particle. Similarly, a single apoB100 molecule is contained per particle of very-low-density lipoprotein (VLDL), intermediate density lipoprotein, LDL and lipoprotein(a). This unique one apoB per particle ratio makes plasma apoB concentration a direct measure of the number of circulating atherogenic lipoproteins. ApoB levels indicate the atherogenic particle concentration independent of the particle cholesterol content, which is variable. While LDL, the major cholesterol-carrying serum lipoprotein, is the primary therapeutic target for management and prevention of atherosclerotic cardiovascular disease, there is strong evidence that apoB is a more accurate indicator of cardiovascular risk than either total cholesterol or LDL cholesterol. This review examines multiple aspects of apoB structure and function, with a focus on the controversy over use of apoB as a therapeutic target in clinical practice. Ongoing coronary artery disease residual risk, despite lipid-lowering treatment, has left patients and clinicians with unsatisfactory options for monitoring cardiovascular health. At the present time, the substitution of apoB for LDL-C in cardiovascular disease prevention guidelines has been deemed unjustified, but discussions continue.
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Yang YX, Li P, Wang P, Zhu BT. 17β-Estradiol-Induced Conformational Changes of Human Microsomal Triglyceride Transfer Protein: A Computational Molecular Modelling Study. Cells 2021; 10:cells10071566. [PMID: 34206252 PMCID: PMC8304645 DOI: 10.3390/cells10071566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/19/2021] [Accepted: 05/05/2021] [Indexed: 11/23/2022] Open
Abstract
Human microsomal triglyceride transfer protein (hMTP) plays an essential role in the assembly of apoB-containing lipoproteins, and has become an important drug target for the treatment of several disease states, such as abetalipoproteinemia, fat malabsorption and familial hypercholesterolemia. hMTP is a heterodimer composed of a larger hMTPα subunit and a smaller hMTPβ subunit (namely, protein disulfide isomerase, hPDI). hPDI can interact with 17β-estradiol (E2), an endogenous female sex hormone. It has been reported that E2 can significantly reduce the blood levels of low-density lipoprotein, cholesterol and triglyceride, and modulate liver lipid metabolism in vivo. However, some of the estrogen’s actions on lipid metabolism are not associated with estrogen receptors (ER), and the exact mechanism underlying estrogen’s ER-independent lipid-modulating action is still not clear at present. In this study, the potential influence of E2 on the stability of the hMTP complex is investigated by jointly using multiple molecular dynamics analyses based on available experimental structures. The molecular dynamics analyses indicate that the hMTP complex in the presence of E2 has reduced interface contacts and surface areas. A steered molecular dynamics analysis shows that the forces required to separate the two subunits (namely, hPDI and hMTPα subunit) of the hMTP complex in the absence of E2 are significantly higher than the forces required to separate the complex in which its hPDI is already bound with E2. E2 makes the interface between hMTPα and hPDI subunits more flexible and less stable. The results of this study suggest that E2-induced conformational changes of the hMTP complex might be a novel mechanism partly accounting for the ER-independent lipid-modulating effect of E2.
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Affiliation(s)
- Yong-Xiao Yang
- Shenzhen Key Laboratory of Steroid Drug Discovery and Development, School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen 518172, China; (Y.-X.Y.); (P.L.); (P.W.)
| | - Peng Li
- Shenzhen Key Laboratory of Steroid Drug Discovery and Development, School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen 518172, China; (Y.-X.Y.); (P.L.); (P.W.)
| | - Pan Wang
- Shenzhen Key Laboratory of Steroid Drug Discovery and Development, School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen 518172, China; (Y.-X.Y.); (P.L.); (P.W.)
- Shenzhen Bay Laboratory, Shenzhen 518055, China
| | - Bao-Ting Zhu
- Shenzhen Key Laboratory of Steroid Drug Discovery and Development, School of Life and Health Sciences, The Chinese University of Hong Kong, Shenzhen 518172, China; (Y.-X.Y.); (P.L.); (P.W.)
- Shenzhen Bay Laboratory, Shenzhen 518055, China
- Correspondence: ; Tel.: +86-755-84273851
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5
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Takahashi M, Okazaki H, Ohashi K, Ogura M, Ishibashi S, Okazaki S, Hirayama S, Hori M, Matsuki K, Yokoyama S, Harada-Shiba M. Current Diagnosis and Management of Abetalipoproteinemia. J Atheroscler Thromb 2021; 28:1009-1019. [PMID: 33994405 PMCID: PMC8560840 DOI: 10.5551/jat.rv17056] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abetalipoproteinemia (ABL) is a rare autosomal recessive disorder caused by biallelic pathogenic mutations in the
MTTP
gene. Deficiency of microsomal triglyceride transfer protein (MTTP) abrogates the assembly of apolipoprotein (apo) B-containing lipoprotein in the intestine and liver, resulting in malabsorption of fat and fat-soluble vitamins and severe hypolipidemia. Patients with ABL typically manifest steatorrhea, vomiting, and failure to thrive in infancy. The deficiency of fat-soluble vitamins progressively develops into a variety of symptoms later in life, including hematological (acanthocytosis, anemia, bleeding tendency, etc.), neuromuscular (spinocerebellar ataxia, peripheral neuropathy, myopathy, etc.), and ophthalmological symptoms (e.g., retinitis pigmentosa). If left untreated, the disease can be debilitating and even lethal by the third decade of life due to the development of severe complications, such as blindness, neuromyopathy, and respiratory failure. High dose vitamin supplementation is the mainstay for treatment and may prevent, delay, or alleviate the complications and improve the prognosis, enabling some patients to live to the eighth decade of life. However, it cannot fully prevent or restore impaired function. Novel therapeutic modalities that improve quality of life and prognosis are awaited. The aim of this review is to 1) summarize the pathogenesis, clinical signs and symptoms, diagnosis, and management of ABL, and 2) propose diagnostic criteria that define eligibility to receive financial support from the Japanese government for patients with ABL as a rare and intractable disease. In addition, our diagnostic criteria and the entry criterion of low-density lipoprotein cholesterol (LDL-C) <15 mg/dL and apoB <15 mg/dL can be useful in universal or opportunistic screening for the disease. Registry research on ABL is currently ongoing to better understand the disease burden and unmet needs of this life-threatening disease with few therapeutic options.
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Affiliation(s)
- Manabu Takahashi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Jichi Medical University
| | - Hiroaki Okazaki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo
| | - Ken Ohashi
- Department of General Internal Medicine, National Cancer Center Hospital
| | - Masatsune Ogura
- Department of Molecular Innovation in Lipidology, National Cerebral and Cardiovascular Center Research Institute
| | - Shun Ishibashi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, School of Medicine, Jichi Medical University
| | - Sachiko Okazaki
- Division for Health Service Promotion, The University of Tokyo
| | - Satoshi Hirayama
- Department of Clinical Laboratory Medicine, Juntendo University Graduate School of Medicine
| | - Mika Hori
- Department of Endocrinology, Research Institute of Environmental Medicine, Nagoya University
| | - Kota Matsuki
- Department of Endocrinology and Metabolism, Hirosaki University Graduate School of Medicine
| | | | - Mariko Harada-Shiba
- Department of Molecular Pathogenesis, National Cerebral and Cardiovascular Center Research Institute
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6
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Sesorova IS, Dimov ID, Kashin AD, Sesorov VV, Karelina NR, Zdorikova MA, Beznoussenko GV, Mirоnоv AA. Cellular and sub-cellular mechanisms of lipid transport from gut to lymph. Tissue Cell 2021; 72:101529. [PMID: 33915359 DOI: 10.1016/j.tice.2021.101529] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 02/26/2021] [Accepted: 03/11/2021] [Indexed: 12/14/2022]
Abstract
Although the general structure of the barrier between the gut and the blood is well known, many details are still missing. Here, we analyse the literature and our own data related to lipid transcytosis through adult mammalian enterocytes, and their absorption into lymph at the tissue level of the intestine. After starvation, the Golgi complex (GC) of enterocytes is in a resting state. The addition of lipids in the form of chyme leads to the initial appearance of pre-chylomicrons (ChMs) in the tubules of the smooth endoplasmic reticulum, which are attached at the basolateral plasma membrane, immediately below the 'belt' of the adhesive junctions. Then pre-ChMs move into the cisternae of the rough endoplasmic reticulum and then into the expansion of the perforated Golgi cisternae. Next, they pass through the GC, and are concentrated in the distensions of the perforated cisternae on the trans-side of the GC. The arrival of pre-ChMs at the GC leads to the transition of the GC to a state of active transport, with formation of intercisternal connections, attachment of cis-most and trans-most perforated cisternae to the medial Golgi cisternae, and disappearance of COPI vesicles. Post-Golgi carriers then deliver ChMs to the basolateral plasma membrane, fuse with it, and secret ChMs into the intercellular space between enterocytes at the level of their interdigitating contacts. Finally, ChMs are squeezed out into the interstitium through pores in the basal membrane, most likely due to the function of the actin-myosin 'cuff' around the interdigitating contacts. These pores appear to be formed by protrusions of the dendritic cells and the enterocytes per se. ChMs are absorbed from the interstitium into the lymphatic capillaries through the special oblique contacts between endothelial cells, which function as valves through the contraction-relaxation of bundles of smooth muscle cells in the interstitium. Lipid overloading of enterocytes results in accumulation of cytoplasmic lipid droplets, an increase in diameter of ChMs, inhibition of intra-Golgi transport, and fusion of ChMs in the interstitium. Here, we summarise and analyse recent findings, and discuss their functional implications.
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Affiliation(s)
- Irina S Sesorova
- Department of Anatomy, Saint Petersburg State Paediatric Medical University, S. Petersburg, Russia
| | - Ivan D Dimov
- Department of Anatomy, Ivanovo State Medical Academy, Ivanovo, Russia
| | - Alexandre D Kashin
- Department of Anatomy, Saint Petersburg State Paediatric Medical University, S. Petersburg, Russia
| | - Vitaly V Sesorov
- Department of Anatomy, Saint Petersburg State Paediatric Medical University, S. Petersburg, Russia
| | | | - Maria A Zdorikova
- Department of Anatomy, Saint Petersburg State Paediatric Medical University, S. Petersburg, Russia
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7
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Anastasia I, Ilacqua N, Raimondi A, Lemieux P, Ghandehari-Alavijeh R, Faure G, Mekhedov SL, Williams KJ, Caicci F, Valle G, Giacomello M, Quiroga AD, Lehner R, Miksis MJ, Toth K, de Aguiar Vallim TQ, Koonin EV, Scorrano L, Pellegrini L. Mitochondria-rough-ER contacts in the liver regulate systemic lipid homeostasis. Cell Rep 2021; 34:108873. [PMID: 33730569 DOI: 10.1016/j.celrep.2021.108873] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/18/2020] [Accepted: 02/23/2021] [Indexed: 12/12/2022] Open
Abstract
Contacts between organelles create microdomains that play major roles in regulating key intracellular activities and signaling pathways, but whether they also regulate systemic functions remains unknown. Here, we report the ultrastructural organization and dynamics of the inter-organellar contact established by sheets of curved rough endoplasmic reticulum closely wrapped around the mitochondria (wrappER). To elucidate the in vivo function of this contact, mouse liver fractions enriched in wrappER-associated mitochondria are analyzed by transcriptomics, proteomics, and lipidomics. The biochemical signature of the wrappER points to a role in the biogenesis of very-low-density lipoproteins (VLDL). Altering wrappER-mitochondria contacts curtails VLDL secretion and increases hepatic fatty acids, lipid droplets, and neutral lipid content. Conversely, acute liver-specific ablation of Mttp, the most upstream regulator of VLDL biogenesis, recapitulates this hepatic dyslipidemia phenotype and promotes remodeling of the wrappER-mitochondria contact. The discovery that liver wrappER-mitochondria contacts participate in VLDL biology suggests an involvement of inter-organelle contacts in systemic lipid homeostasis.
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Affiliation(s)
- Irene Anastasia
- Graduate Program in Neuroscience, Faculty of Medicine, Laval University, Quebec, QC, Canada; Mitochondria Biology Laboratory, Brain Research Center, Quebec, QC, Canada
| | - Nicolò Ilacqua
- Graduate Program in Neuroscience, Faculty of Medicine, Laval University, Quebec, QC, Canada; Mitochondria Biology Laboratory, Brain Research Center, Quebec, QC, Canada
| | - Andrea Raimondi
- Experimental Imaging Center, San Raffaele Scientific Institute, Milan, Italy
| | - Philippe Lemieux
- Mitochondria Biology Laboratory, Brain Research Center, Quebec, QC, Canada
| | | | - Guilhem Faure
- Broad Institute of MIT and Harvard, Cambridge, MA, USA; National Center for Biotechnology Information, NLM, NIH, Bethesda, MD, USA
| | - Sergei L Mekhedov
- National Center for Biotechnology Information, NLM, NIH, Bethesda, MD, USA
| | - Kevin J Williams
- Department of Biological Chemistry, Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | | | - Giorgio Valle
- Department of Biology, University of Padua, Padua, Italy
| | | | - Ariel D Quiroga
- Instituto de Fisiología Experimental, CONICET, UNR, Rosario, Argentina; Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Richard Lehner
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Michael J Miksis
- Department of Engineering Science and Applied Mathematics, Northwestern University, Evanston, IL, USA
| | - Katalin Toth
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Thomas Q de Aguiar Vallim
- Department of Biological Chemistry, Geffen School of Medicine, UCLA, Los Angeles, CA, USA; Department of Medicine, Division of Cardiology, UCLA, Los Angeles, CA, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, NLM, NIH, Bethesda, MD, USA
| | - Luca Scorrano
- Department of Biology, University of Padua, Padua, Italy
| | - Luca Pellegrini
- Mitochondria Biology Laboratory, Brain Research Center, Quebec, QC, Canada; Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Quebec, QC, Canada.
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8
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PDI-Regulated Disulfide Bond Formation in Protein Folding and Biomolecular Assembly. Molecules 2020; 26:molecules26010171. [PMID: 33396541 PMCID: PMC7794689 DOI: 10.3390/molecules26010171] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/25/2020] [Accepted: 12/28/2020] [Indexed: 02/06/2023] Open
Abstract
Disulfide bonds play a pivotal role in maintaining the natural structures of proteins to ensure their performance of normal biological functions. Moreover, biological molecular assembly, such as the gluten network, is also largely dependent on the intermolecular crosslinking via disulfide bonds. In eukaryotes, the formation and rearrangement of most intra- and intermolecular disulfide bonds in the endoplasmic reticulum (ER) are mediated by protein disulfide isomerases (PDIs), which consist of multiple thioredoxin-like domains. These domains assist correct folding of proteins, as well as effectively prevent the aggregation of misfolded ones. Protein misfolding often leads to the formation of pathological protein aggregations that cause many diseases. On the other hand, glutenin aggregation and subsequent crosslinking are required for the formation of a rheologically dominating gluten network. Herein, the mechanism of PDI-regulated disulfide bond formation is important for understanding not only protein folding and associated diseases, but also the formation of functional biomolecular assembly. This review systematically illustrated the process of human protein disulfide isomerase (hPDI) mediated disulfide bond formation and complemented this with the current mechanism of wheat protein disulfide isomerase (wPDI) catalyzed formation of gluten networks.
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9
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Wang L, Yu J, Wang CC. Protein disulfide isomerase is regulated in multiple ways: Consequences for conformation, activities, and pathophysiological functions. Bioessays 2020; 43:e2000147. [PMID: 33155310 DOI: 10.1002/bies.202000147] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 12/13/2022]
Abstract
Protein disulfide isomerase (PDI) is one of the most abundant and critical protein folding catalysts in the endoplasmic reticulum of eukaryotic cells. PDI consists of four thioredoxin domains and interacts with a wide range of substrate and partner proteins due to its intrinsic conformational flexibility. PDI plays multifunctional roles in a variety of pathophysiological events, both as an oxidoreductase and a molecular chaperone. Recent studies have revealed that the conformation and activity of PDI can be regulated in multiple ways, including posttranslational modification and substrate/ligand binding. Here, we summarize recent advances in understanding the function and regulation of PDI in different pathological and physiological events. We propose that the multifunctional roles of PDI are regulated by multiple mechanisms. Furthermore, we discuss future directions for the study of PDI, emphasizing how different regulatory modes are linked to the conformational changes and biological functions of PDI in the context of diverse pathophysiologies.
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Affiliation(s)
- Lei Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jiaojiao Yu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Chih-Chen Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
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10
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Wilson MH, Rajan S, Danoff A, White RJ, Hensley MR, Quinlivan VH, Recacha R, Thierer JH, Tan FJ, Busch-Nentwich EM, Ruddock L, Hussain MM, Farber SA. A point mutation decouples the lipid transfer activities of microsomal triglyceride transfer protein. PLoS Genet 2020; 16:e1008941. [PMID: 32760060 PMCID: PMC7444587 DOI: 10.1371/journal.pgen.1008941] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 08/18/2020] [Accepted: 06/17/2020] [Indexed: 01/08/2023] Open
Abstract
Apolipoprotein B-containing lipoproteins (B-lps) are essential for the transport of hydrophobic dietary and endogenous lipids through the circulation in vertebrates. Zebrafish embryos produce large numbers of B-lps in the yolk syncytial layer (YSL) to move lipids from yolk to growing tissues. Disruptions in B-lp production perturb yolk morphology, readily allowing for visual identification of mutants with altered B-lp metabolism. Here we report the discovery of a missense mutation in microsomal triglyceride transfer protein (Mtp), a protein that is essential for B-lp production. This mutation of a conserved glycine residue to valine (zebrafish G863V, human G865V) reduces B-lp production and results in yolk opacity due to aberrant accumulation of cytoplasmic lipid droplets in the YSL. However, this phenotype is milder than that of the previously reported L475P stalactite (stl) mutation. MTP transfers lipids, including triglycerides and phospholipids, to apolipoprotein B in the ER for B-lp assembly. In vitro lipid transfer assays reveal that while both MTP mutations eliminate triglyceride transfer activity, the G863V mutant protein unexpectedly retains ~80% of phospholipid transfer activity. This residual phospholipid transfer activity of the G863V mttp mutant protein is sufficient to support the secretion of small B-lps, which prevents intestinal fat malabsorption and growth defects observed in the mttpstl/stl mutant zebrafish. Modeling based on the recent crystal structure of the heterodimeric human MTP complex suggests the G865V mutation may block triglyceride entry into the lipid-binding cavity. Together, these data argue that selective inhibition of MTP triglyceride transfer activity may be a feasible therapeutic approach to treat dyslipidemia and provide structural insight for drug design. These data also highlight the power of yolk transport studies to identify proteins critical for B-lp biology.
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Affiliation(s)
- Meredith H. Wilson
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, United States of America
| | - Sujith Rajan
- New York University Long Island School of Medicine, Mineola, New York, United States of America
| | - Aidan Danoff
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, United States of America
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Richard J. White
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
- Cambridge Institute of Therapeutic Immunology & Infectious Disease, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Monica R. Hensley
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, United States of America
| | - Vanessa H. Quinlivan
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, United States of America
| | - Rosario Recacha
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - James H. Thierer
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, United States of America
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Frederick J. Tan
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, United States of America
| | - Elisabeth M. Busch-Nentwich
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
- Cambridge Institute of Therapeutic Immunology & Infectious Disease, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Lloyd Ruddock
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - M. Mahmood Hussain
- New York University Long Island School of Medicine, Mineola, New York, United States of America
| | - Steven A. Farber
- Department of Embryology, Carnegie Institution for Science, Baltimore, Maryland, United States of America
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
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11
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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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12
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Abstract
This study provides a structure for microsomal triglyceride transfer protein, a key protein in lipid metabolism and transport. Microsomal triglyceride transfer protein is linked to a human disease state, abetalipoproteinemia. The structure helps us to understand how this protein functions and gives a rationale for how previously reported mutations result in loss of function of the protein and hence, cause disease. The structure also provides a means for rational drug design to treat cardiovascular disease, hypercholesterolemia, and obesity. Microsomal triglyceride transfer protein is composed of 2 subunits. The β-subunit, protein disulfide isomerase (PDI), also acts independently as a protein folding catalyst. The structure that we present here gives insights into how PDI functions in protein folding. Microsomal triglyceride transfer protein (MTP) plays an essential role in lipid metabolism, especially in the biogenesis of very low-density lipoproteins and chylomicrons via the transfer of neutral lipids and the assembly of apoB-containing lipoproteins. Our understanding of the molecular mechanisms of MTP has been hindered by a lack of structural information of this heterodimeric complex comprising an MTPα subunit and a protein disulfide isomerase (PDI) β-subunit. The structure of MTP presented here gives important insights into the potential mechanisms of action of this essential lipid transfer molecule, structure-based rationale for previously reported disease-causing mutations, and a means for rational drug design against cardiovascular disease and obesity. In contrast to the previously reported structure of lipovitellin, which has a funnel-like lipid-binding cavity, the lipid-binding site is encompassed in a β-sandwich formed by 2 β-sheets from the C-terminal domain of MTPα. The lipid-binding cavity of MTPα is large enough to accommodate a single lipid. PDI independently has a major role in oxidative protein folding in the endoplasmic reticulum. Comparison of the mechanism of MTPα binding by PDI with previously published structures gives insights into large protein substrate binding by PDI and suggests that the previous structures of human PDI represent the “substrate-bound” and “free” states rather than differences arising from redox state.
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Prachasitthisak N, Tanpowpong P, Tim-Aroon T, Treepongkaruna S, Chongviriyaphan N, Vithayasai N, Iamopas O, Wattanasirichaigoon D. Two infants with abetalipoproteinemia: Classic versus atypical presentation. Pediatr Int 2019; 61:508-509. [PMID: 31087595 DOI: 10.1111/ped.13822] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/22/2018] [Accepted: 11/13/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Noparat Prachasitthisak
- Division of Gastroenterology, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.,Division of Gastroenterology Unit, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Pornthep Tanpowpong
- Division of Gastroenterology, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Thipwimol Tim-Aroon
- Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Suporn Treepongkaruna
- Division of Gastroenterology, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Nalinee Chongviriyaphan
- Division of Nutrition, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Niyada Vithayasai
- Division of Gastroenterology Unit, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Orawan Iamopas
- Nutrition Unit, Department of Pediatrics, Queen Sirikit National Institute of Child Health, Bangkok, Thailand
| | - Duangrurdee Wattanasirichaigoon
- Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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14
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Doonan LM, Fisher EA, Brodsky JL. Can modulators of apolipoproteinB biogenesis serve as an alternate target for cholesterol-lowering drugs? Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:762-771. [PMID: 29627384 DOI: 10.1016/j.bbalip.2018.03.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 03/07/2018] [Accepted: 03/27/2018] [Indexed: 12/23/2022]
Abstract
Understanding the molecular defects underlying cardiovascular disease is necessary for the development of therapeutics. The most common method to lower circulating lipids, which reduces the incidence of cardiovascular disease, is statins, but other drugs are now entering the clinic, some of which have been approved. Nevertheless, patients cannot tolerate some of these therapeutics, the drugs are costly, and/or the treatments are approved for only rare forms of disease. Efforts to find alternative treatments have focused on other factors, such as apolipoproteinB (apoB), which transports cholesterol in the blood stream. The levels of apoB are regulated by endoplasmic reticulum (ER) associated degradation as well as by a post ER degradation pathway in model systems, and we suggest that these events provide novel therapeutic targets. We discuss first how cardiovascular disease arises and how cholesterol is regulated, and then summarize the mechanisms of action of existing treatments for cardiovascular disease. We then review the apoB biosynthetic pathway, focusing on steps that might be amenable to therapeutic interventions.
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Affiliation(s)
- Lynley M Doonan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Edward A Fisher
- Departments of Medicine (Cardiology) and Cell Biology and the Marc and Ruti Bell Program in Vascular Biology, New York University School of Medicine, New York, NY 10016, United States
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States.
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15
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Liu Y, Conlon DM, Bi X, Slovik KJ, Shi J, Edelstein HI, Millar JS, Javaheri A, Cuchel M, Pashos EE, Iqbal J, Hussain MM, Hegele RA, Yang W, Duncan SA, Rader DJ, Morrisey EE. Lack of MTTP Activity in Pluripotent Stem Cell-Derived Hepatocytes and Cardiomyocytes Abolishes apoB Secretion and Increases Cell Stress. Cell Rep 2018; 19:1456-1466. [PMID: 28514664 DOI: 10.1016/j.celrep.2017.04.064] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 02/22/2017] [Accepted: 04/21/2017] [Indexed: 01/26/2023] Open
Abstract
Abetalipoproteinemia (ABL) is an inherited disorder of lipoprotein metabolism resulting from mutations in microsomal triglyceride transfer protein (MTTP). In addition to expression in the liver and intestine, MTTP is expressed in cardiomyocytes, and cardiomyopathy has been reported in several ABL cases. Using induced pluripotent stem cells (iPSCs) generated from an ABL patient homozygous for a missense mutation (MTTPR46G), we show that human hepatocytes and cardiomyocytes exhibit defects associated with ABL disease, including loss of apolipoprotein B (apoB) secretion and intracellular accumulation of lipids. MTTPR46G iPSC-derived cardiomyocytes failed to secrete apoB, accumulated intracellular lipids, and displayed increased cell death, suggesting intrinsic defects in lipid metabolism due to loss of MTTP function. Importantly, these phenotypes were reversed after the correction of the MTTPR46G mutation by CRISPR/Cas9 gene editing. Together, these data reveal clear cellular defects in iPSC-derived hepatocytes and cardiomyocytes lacking MTTP activity, including a cardiomyocyte-specific regulated stress response to elevated lipids.
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Affiliation(s)
- Ying Liu
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Donna M Conlon
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Xin Bi
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Katherine J Slovik
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jianting Shi
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hailey I Edelstein
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - John S Millar
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ali Javaheri
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Marina Cuchel
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Evanthia E Pashos
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jahangir Iqbal
- Department of Cell Biology and Pediatrics, State University of New York Downstate Medicine Center, Brooklyn, NY 11203, USA
| | - M Mahmood Hussain
- Department of Cell Biology and Pediatrics, State University of New York Downstate Medicine Center, Brooklyn, NY 11203, USA
| | - Robert A Hegele
- Department of Medicine and Robarts Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, N6A 5C1, Canada
| | - Wenli Yang
- Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Stephen A Duncan
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Daniel J Rader
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Edward E Morrisey
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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16
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Khan MT, Dalvin S, Nilsen F, Male R. Microsomal triglyceride transfer protein in the ectoparasitic crustacean salmon louse ( Lepeophtheirus salmonis). J Lipid Res 2017; 58:1613-1623. [PMID: 28601811 PMCID: PMC5538283 DOI: 10.1194/jlr.m076430] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 05/10/2017] [Indexed: 11/20/2022] Open
Abstract
The salmon louse, Lepeophtheirus salmonis, is an endemic ectoparasite on salmonid fish that is challenging for the salmon farming industry and wild fish. Salmon lice produce high numbers of offspring, necessitating sequestration of large amounts of lipids into growing oocytes as a major energy source for larvae, most probably mediated by lipoproteins. The microsomal triglyceride transfer protein (MTP) is essential for the assembly of lipoproteins. Salmon lice have three L. salmonis MTP (LsMTP) transcript variants encoding two different protein isoforms, which are predicted to contain three β-sheets (N, C, and A) and a central helical domain, similar to MTPs from other species. In adult females, the LsMTPs are differently transcribed in the sub-cuticular tissues, the intestine, the ovary, and in the mature eggs. RNA interference-mediated knockdown of LsMTP in mature females gave offspring with significantly fewer neutral lipids in their yolk and only 10-30% survival. The present study suggests the importance of LsMTP in reproduction and lipid metabolism in adult female L. salmonis, a possible metabolic bottleneck that could be exploited for the development of new anti-parasitic treatment methods.
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Affiliation(s)
| | - Sussie Dalvin
- Sea Lice Research Centre, Institute of Marine Research, 5817 Bergen, Norway
| | - Frank Nilsen
- Departments of Biology University of Bergen, N-5020 Bergen, Norway
| | - Rune Male
- Molecular Biology, Sea Lice Research Centre, University of Bergen, N-5020 Bergen, Norway.
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17
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Wang D, Du S, Cazenave-Gassiot A, Ge J, Lee JS, Wenk MR, Yao SQ. Global Mapping of Protein-Lipid Interactions by Using Modified Choline-Containing Phospholipids Metabolically Synthesized in Live Cells. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201702509] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Danyang Wang
- Department of Chemistry; National University of Singapore; 3 Science Drive 3 Singapore 117543 Singapore
| | - Shubo Du
- Department of Chemistry; National University of Singapore; 3 Science Drive 3 Singapore 117543 Singapore
| | | | - Jingyan Ge
- Institute of Bioengineering; Zhejiang University of Technology; China
| | - Jun-Seok Lee
- Department of Biological Chemistry; University of Science & Technology; South Korea
| | - Markus R. Wenk
- Department of Biological Sciences; National University of Singapore; Singapore
| | - Shao Q. Yao
- Department of Chemistry; National University of Singapore; 3 Science Drive 3 Singapore 117543 Singapore
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18
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Wang D, Du S, Cazenave-Gassiot A, Ge J, Lee JS, Wenk MR, Yao SQ. Global Mapping of Protein-Lipid Interactions by Using Modified Choline-Containing Phospholipids Metabolically Synthesized in Live Cells. Angew Chem Int Ed Engl 2017; 56:5829-5833. [DOI: 10.1002/anie.201702509] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Indexed: 01/19/2023]
Affiliation(s)
- Danyang Wang
- Department of Chemistry; National University of Singapore; 3 Science Drive 3 Singapore 117543 Singapore
| | - Shubo Du
- Department of Chemistry; National University of Singapore; 3 Science Drive 3 Singapore 117543 Singapore
| | | | - Jingyan Ge
- Institute of Bioengineering; Zhejiang University of Technology; China
| | - Jun-Seok Lee
- Department of Biological Chemistry; University of Science & Technology; South Korea
| | - Markus R. Wenk
- Department of Biological Sciences; National University of Singapore; Singapore
| | - Shao Q. Yao
- Department of Chemistry; National University of Singapore; 3 Science Drive 3 Singapore 117543 Singapore
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19
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Soares Moretti AI, Martins Laurindo FR. Protein disulfide isomerases: Redox connections in and out of the endoplasmic reticulum. Arch Biochem Biophys 2016; 617:106-119. [PMID: 27889386 DOI: 10.1016/j.abb.2016.11.007] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 11/08/2016] [Accepted: 11/21/2016] [Indexed: 12/13/2022]
Abstract
Protein disulfide isomerases are thiol oxidoreductase chaperones from thioredoxin superfamily. As redox folding catalysts from the endoplasmic reticulum (ER), their roles in ER-related redox homeostasis and signaling are well-studied. PDIA1 exerts thiol oxidation/reduction and isomerization, plus chaperone effects. Also, substantial evidence indicates that PDIs regulate thiol-disulfide switches in other cell locations such as cell surface and possibly cytosol. Subcellular PDI translocation routes remain unclear and seem Golgi-independent. The list of signaling and structural proteins reportedly regulated by PDIs keeps growing, via thiol switches involving oxidation, reduction and isomerization, S-(de)nytrosylation, (de)glutathyonylation and protein oligomerization. PDIA1 is required for agonist-triggered Nox NADPH oxidase activation and cell migration in vascular cells and macrophages, while PDIA1-dependent cytoskeletal regulation appears a converging pathway. Extracellularly, PDIs crucially regulate thiol redox signaling of thrombosis/platelet activation, e.g., integrins, and PDIA1 supports expansive caliber remodeling during injury repair via matrix/cytoskeletal organization. Some proteins display regulatory PDI-like motifs. PDI effects are orchestrated by expression levels or post-translational modifications. PDI is redox-sensitive, although probably not a mass-effect redox sensor due to kinetic constraints. Rather, the "all-in-one" organization of its peculiar redox/chaperone properties likely provide PDIs with precision and versatility in redox signaling, making them promising therapeutic targets.
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Affiliation(s)
- Ana Iochabel Soares Moretti
- Vascular Biology Laboratory, Heart Institute (InCor), University of São Paulo, School of Medicine, São Paulo, Brazil
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20
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Walsh MT, Hussain MM. Targeting microsomal triglyceride transfer protein and lipoprotein assembly to treat homozygous familial hypercholesterolemia. Crit Rev Clin Lab Sci 2016; 54:26-48. [PMID: 27690713 DOI: 10.1080/10408363.2016.1221883] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Homozygous familial hypercholesterolemia (HoFH) is a polygenic disease arising from defects in the clearance of plasma low-density lipoprotein (LDL), which results in extremely elevated plasma LDL cholesterol (LDL-C) and increased risk of atherosclerosis, coronary heart disease, and premature death. Conventional lipid-lowering therapies, such as statins and ezetimibe, are ineffective at lowering plasma cholesterol to safe levels in these patients. Other therapeutic options, such as LDL apheresis and liver transplantation, are inconvenient, costly, and not readily available. Recently, lomitapide was approved by the Federal Drug Administration as an adjunct therapy for the treatment of HoFH. Lomitapide inhibits microsomal triglyceride transfer protein (MTP), reduces lipoprotein assembly and secretion, and lowers plasma cholesterol levels by over 50%. Here, we explain the steps involved in lipoprotein assembly, summarize the role of MTP in lipoprotein assembly, explore the clinical and molecular basis of HoFH, and review pre-clinical studies and clinical trials with lomitapide and other MTP inhibitors for the treatment of HoFH. In addition, ongoing research and new approaches underway for better treatment modalities are discussed.
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Affiliation(s)
- Meghan T Walsh
- a School of Graduate Studies, Molecular and Cell Biology Program, State University of New York Downstate Medical Center , Brooklyn , NY , USA.,b Department of Cell Biology , State University of New York Downstate Medical Center , Brooklyn , NY , USA
| | - M Mahmood Hussain
- b Department of Cell Biology , State University of New York Downstate Medical Center , Brooklyn , NY , USA.,c Department of Pediatrics , SUNY Downstate Medical Center , Brooklyn , NY , USA.,d VA New York Harbor Healthcare System , Brooklyn , NY , USA , and.,e Winthrop University Hospital , Mineola , NY , USA
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21
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Mansbach CM, Siddiqi S. Control of chylomicron export from the intestine. Am J Physiol Gastrointest Liver Physiol 2016; 310:G659-68. [PMID: 26950854 DOI: 10.1152/ajpgi.00228.2015] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 02/22/2016] [Indexed: 01/31/2023]
Abstract
The control of chylomicron output by the intestine is a complex process whose outlines have only recently come into focus. In this review we will cover aspects of chylomicron formation and prechylomicron vesicle generation that elucidate potential control points. Substrate (dietary fatty acids and monoacylglycerols) availability is directly related to the output rate of chylomicrons. These substrates must be converted to triacylglycerol before packaging in prechylomicrons by a series of endoplasmic reticulum (ER)-localized acylating enzymes that rapidly convert fatty acids and monoacylglycerols to triacylglycerol. The packaging of the prechylomicron with triacylglycerol is controlled by the microsomal triglyceride transport protein, another potential limiting step. The prechylomicrons, once loaded with triacylglycerol, are ready to be incorporated into the prechylomicron transport vesicle that transports the prechylomicron from the ER to the Golgi. Control of this exit step from the ER, the rate-limiting step in the transcellular movement of the triacylglycerol, is a multistep process involving the activation of PKCζ, the phosphorylation of Sar1b, releasing the liver fatty acid binding protein from a heteroquatromeric complex, which enables it to bind to the ER and organize the prechylomicron transport vesicle budding complex. We propose that control of PKCζ activation is the major physiological regulator of chylomicron output.
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Affiliation(s)
- Charles M Mansbach
- Department of Medicine, Division of Gastroenterology, University of Tennessee Health Science Center, Memphis, Tennessee; and Department of Medicine, Veterans Affairs Medical Center, Memphis, Tennessee
| | - Shahzad Siddiqi
- Department of Medicine, Division of Gastroenterology, University of Tennessee Health Science Center, Memphis, Tennessee; and Department of Medicine, Veterans Affairs Medical Center, Memphis, Tennessee
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22
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Heidker RM, Caiozzi GC, Ricketts ML. Grape Seed Procyanidins and Cholestyramine Differentially Alter Bile Acid and Cholesterol Homeostatic Gene Expression in Mouse Intestine and Liver. PLoS One 2016; 11:e0154305. [PMID: 27111442 PMCID: PMC4844140 DOI: 10.1371/journal.pone.0154305] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 04/12/2016] [Indexed: 01/05/2023] Open
Abstract
Bile acid (BA) sequestrants, lipid-lowering agents, may be prescribed as a monotherapy or combination therapy to reduce the risk of coronary artery disease. Over 33% of adults in the United States use complementary and alternative medicine strategies, and we recently reported that grape seed procyanidin extract (GSPE) reduces enterohepatic BA recirculation as a means to reduce serum triglyceride (TG) levels. The current study was therefore designed to assess the effects on BA, cholesterol and TG homeostatic gene expression following co-administration with GSPE and the BA sequestrant, cholestyramine (CHY). Eight-week old male C57BL/6 mice were treated for 4 weeks with either a control or 2% CHY-supplemented diet, after which, they were administered vehicle or GSPE for 14 hours. Liver and intestines were harvested and gene expression was analyzed. BA, cholesterol, non-esterified fatty acid and TG levels were also analyzed in serum and feces. Results reveal that GSPE treatment alone, and co-administration with CHY, regulates BA, cholesterol and TG metabolism differently than CHY administration alone. Notably, GSPE decreased intestinal apical sodium-dependent bile acid transporter (Asbt) gene expression, while CHY significantly induced expression. Administration with GSPE or CHY robustly induced hepatic BA biosynthetic gene expression, especially cholesterol 7α-hydroxylase (Cyp7a1), compared to control, while co-administration further enhanced expression. Treatment with CHY induced both intestinal and hepatic cholesterologenic gene expression, while co-administration with GSPE attenuated the CHY-induced increase in the liver but not intestine. CHY also induced hepatic lipogenic gene expression, which was attenuated by co-administration with GSPE. Consequently, a 25% decrease in serum TG levels was observed in the CHY+GSPE group, compared to the CHY group. Collectively, this study presents novel evidence demonstrating that GSPE provides additive and complementary efficacy as a lipid-lowering combination therapy in conjunction with CHY by attenuating hepatic cholesterol synthesis, enhancing BA biosynthesis and decreasing lipogenesis, which warrants further investigation.
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Affiliation(s)
- Rebecca M. Heidker
- Department of Agriculture, Nutrition and Veterinary Sciences, University of Nevada Reno, Reno, Nevada, United States of America
| | - Gianella C. Caiozzi
- Department of Agriculture, Nutrition and Veterinary Sciences, University of Nevada Reno, Reno, Nevada, United States of America
| | - Marie-Louise Ricketts
- Department of Agriculture, Nutrition and Veterinary Sciences, University of Nevada Reno, Reno, Nevada, United States of America
- * E-mail:
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23
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Walsh MT, Iqbal J, Josekutty J, Soh J, Di Leo E, Özaydin E, Gündüz M, Tarugi P, Hussain MM. Novel Abetalipoproteinemia Missense Mutation Highlights the Importance of the N-Terminal β-Barrel in Microsomal Triglyceride Transfer Protein Function. ACTA ACUST UNITED AC 2015. [PMID: 26224785 DOI: 10.1161/circgenetics.115.001106] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The use of microsomal triglyceride transfer protein (MTP) inhibitors is limited to severe hyperlipidemias because of associated hepatosteatosis and gastrointestinal adverse effects. Comprehensive knowledge about the structure-function of MTP might help design new molecules that avoid steatosis. Characterization of mutations in MTP causing abetalipoproteinemia has revealed that the central α-helical and C-terminal β-sheet domains are important for protein disulfide isomerase binding and lipid transfer activity. Our aim was to identify and characterize mutations in the N-terminal domain to understand its function. METHODS AND RESULTS We identified a novel missense mutation (D169V) in a 4-month-old Turkish male child with severe signs of abetalipoproteinemia. To study the effect of this mutation on MTP function, we created mutants via site-directed mutagenesis. Although D169V was expressed in the endoplasmic reticulum and interacted with apolipoprotein B (apoB) 17, it was unable to bind protein disulfide isomerase, transfer lipids, and support apoB secretion. Computational modeling suggested that D169 could form an internal salt bridge with K187 and K189. Mutagenesis of these lysines to leucines abolished protein disulfide isomerase heterodimerization, lipid transfer, and apoB secretion, without affecting apoB17 binding. Furthermore, mutants with preserved charges (D169E, K187R, and K189R) rescued these activities. CONCLUSIONS D169V is detrimental because it disrupts an internal salt bridge leading to loss of protein disulfide isomerase binding and lipid transfer activities; however, it does not affect apoB binding. Thus, the N-terminal domain of MTP is also important for its lipid transfer activity.
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Affiliation(s)
- Meghan T Walsh
- From the School of Graduate Studies, Molecular and Cell Biology Program (M.T.W., J.J., J.S.), Department of Cell Biology (M.T.W., J.I., J.J., J.S., M.M.H.), Department of Pediatrics (M.M.H.), State University of New York Downstate Medical Center, Brooklyn, NY; Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy (E.D.L., P.T.); Infancy Services, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (E.O); Department of Nutrition and Metabolism, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (M.G.); and Department of Research, VA New York Harbor Healthcare System, Brooklyn, NY (M.M.H.)
| | - Jahangir Iqbal
- From the School of Graduate Studies, Molecular and Cell Biology Program (M.T.W., J.J., J.S.), Department of Cell Biology (M.T.W., J.I., J.J., J.S., M.M.H.), Department of Pediatrics (M.M.H.), State University of New York Downstate Medical Center, Brooklyn, NY; Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy (E.D.L., P.T.); Infancy Services, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (E.O); Department of Nutrition and Metabolism, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (M.G.); and Department of Research, VA New York Harbor Healthcare System, Brooklyn, NY (M.M.H.)
| | - Joby Josekutty
- From the School of Graduate Studies, Molecular and Cell Biology Program (M.T.W., J.J., J.S.), Department of Cell Biology (M.T.W., J.I., J.J., J.S., M.M.H.), Department of Pediatrics (M.M.H.), State University of New York Downstate Medical Center, Brooklyn, NY; Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy (E.D.L., P.T.); Infancy Services, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (E.O); Department of Nutrition and Metabolism, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (M.G.); and Department of Research, VA New York Harbor Healthcare System, Brooklyn, NY (M.M.H.)
| | - James Soh
- From the School of Graduate Studies, Molecular and Cell Biology Program (M.T.W., J.J., J.S.), Department of Cell Biology (M.T.W., J.I., J.J., J.S., M.M.H.), Department of Pediatrics (M.M.H.), State University of New York Downstate Medical Center, Brooklyn, NY; Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy (E.D.L., P.T.); Infancy Services, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (E.O); Department of Nutrition and Metabolism, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (M.G.); and Department of Research, VA New York Harbor Healthcare System, Brooklyn, NY (M.M.H.)
| | - Enza Di Leo
- From the School of Graduate Studies, Molecular and Cell Biology Program (M.T.W., J.J., J.S.), Department of Cell Biology (M.T.W., J.I., J.J., J.S., M.M.H.), Department of Pediatrics (M.M.H.), State University of New York Downstate Medical Center, Brooklyn, NY; Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy (E.D.L., P.T.); Infancy Services, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (E.O); Department of Nutrition and Metabolism, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (M.G.); and Department of Research, VA New York Harbor Healthcare System, Brooklyn, NY (M.M.H.)
| | - Eda Özaydin
- From the School of Graduate Studies, Molecular and Cell Biology Program (M.T.W., J.J., J.S.), Department of Cell Biology (M.T.W., J.I., J.J., J.S., M.M.H.), Department of Pediatrics (M.M.H.), State University of New York Downstate Medical Center, Brooklyn, NY; Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy (E.D.L., P.T.); Infancy Services, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (E.O); Department of Nutrition and Metabolism, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (M.G.); and Department of Research, VA New York Harbor Healthcare System, Brooklyn, NY (M.M.H.)
| | - Mehmet Gündüz
- From the School of Graduate Studies, Molecular and Cell Biology Program (M.T.W., J.J., J.S.), Department of Cell Biology (M.T.W., J.I., J.J., J.S., M.M.H.), Department of Pediatrics (M.M.H.), State University of New York Downstate Medical Center, Brooklyn, NY; Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy (E.D.L., P.T.); Infancy Services, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (E.O); Department of Nutrition and Metabolism, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (M.G.); and Department of Research, VA New York Harbor Healthcare System, Brooklyn, NY (M.M.H.)
| | - Patrizia Tarugi
- From the School of Graduate Studies, Molecular and Cell Biology Program (M.T.W., J.J., J.S.), Department of Cell Biology (M.T.W., J.I., J.J., J.S., M.M.H.), Department of Pediatrics (M.M.H.), State University of New York Downstate Medical Center, Brooklyn, NY; Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy (E.D.L., P.T.); Infancy Services, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (E.O); Department of Nutrition and Metabolism, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (M.G.); and Department of Research, VA New York Harbor Healthcare System, Brooklyn, NY (M.M.H.)
| | - M Mahmood Hussain
- From the School of Graduate Studies, Molecular and Cell Biology Program (M.T.W., J.J., J.S.), Department of Cell Biology (M.T.W., J.I., J.J., J.S., M.M.H.), Department of Pediatrics (M.M.H.), State University of New York Downstate Medical Center, Brooklyn, NY; Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy (E.D.L., P.T.); Infancy Services, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (E.O); Department of Nutrition and Metabolism, Ankara Children's Health and Diseases Hematology-Oncology Training and Research Hospital, Ankara, Turkey (M.G.); and Department of Research, VA New York Harbor Healthcare System, Brooklyn, NY (M.M.H.).
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Small molecule-induced oxidation of protein disulfide isomerase is neuroprotective. Proc Natl Acad Sci U S A 2015; 112:E2245-52. [PMID: 25848045 DOI: 10.1073/pnas.1500439112] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein disulfide isomerase (PDI) is a chaperone protein in the endoplasmic reticulum that is up-regulated in mouse models of, and brains of patients with, neurodegenerative diseases involving protein misfolding. PDI's role in these diseases, however, is not fully understood. Here, we report the discovery of a reversible, neuroprotective lead optimized compound (LOC)14, that acts as a modulator of PDI. LOC14 was identified using a high-throughput screen of ∼10,000 lead-optimized compounds for potent rescue of viability of PC12 cells expressing mutant huntingtin protein, followed by an evaluation of compounds on PDI reductase activity in an in vitro screen. Isothermal titration calorimetry and fluorescence experiments revealed that binding to PDI was reversible with a Kd of 62 nM, suggesting LOC14 to be the most potent PDI inhibitor reported to date. Using 2D heteronuclear single quantum correlation NMR experiments, we were able to map the binding site of LOC14 as being adjacent to the active site and to observe that binding of LOC14 forces PDI to adopt an oxidized conformation. Furthermore, we found that LOC14-induced oxidation of PDI has a neuroprotective effect not only in cell culture, but also in corticostriatal brain slice cultures. LOC14 exhibited high stability in mouse liver microsomes and blood plasma, low intrinsic microsome clearance, and low plasma-protein binding. These results suggest that LOC14 is a promising lead compound to evaluate the potential therapeutic effects of modulating PDI in animal models of disease.
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25
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Liang R, Shen XL, Zhang B, Li Y, Xu W, Zhao C, Luo Y, Huang K. Apoptosis signal-regulating kinase 1 promotes Ochratoxin A-induced renal cytotoxicity. Sci Rep 2015; 5:8078. [PMID: 25627963 PMCID: PMC5389036 DOI: 10.1038/srep08078] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 01/05/2015] [Indexed: 01/04/2023] Open
Abstract
Oxidative stress and apoptosis are involved in Ochratoxin A (OTA)-induced renal cytotoxicity. Apoptosis signal-regulating kinase 1 (ASK1) is a Mitogen-Activated Protein Kinase Kinase Kinase (MAPKKK, MAP3K) family member that plays an important role in oxidative stress-induced cell apoptosis. In this study, we performed RNA interference of ASK1 in HEK293 cells and employed an iTRAQ-based quantitative proteomics approach to globally investigate the regulatory mechanism of ASK1 in OTA-induced renal cytotoxicity. Our results showed that ASK1 knockdown alleviated OTA-induced ROS generation and Δψm loss and thus desensitized the cells to OTA-induced apoptosis. We identified 33 and 24 differentially expressed proteins upon OTA treatment in scrambled and ASK1 knockdown cells, respectively. Pathway classification and analysis revealed that ASK1 participated in OTA-induced inhibition of mRNA splicing, nucleotide metabolism, the cell cycle, DNA repair, and the activation of lipid metabolism. We concluded that ASK1 plays an essential role in promoting OTA-induced renal cytotoxicity.
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Affiliation(s)
- Rui Liang
- Laboratory of food safety and molecular biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R. China
| | - Xiao Li Shen
- 1] Laboratory of food safety and molecular biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R. China [2] School of Public Health, Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Boyang Zhang
- Laboratory of food safety and molecular biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R. China
| | - Yuzhe Li
- Laboratory of food safety and molecular biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R. China
| | - Wentao Xu
- Laboratory of food safety and molecular biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R. China
| | - Changhui Zhao
- Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, USA
| | - YunBo Luo
- Laboratory of food safety and molecular biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R. China
| | - Kunlun Huang
- Laboratory of food safety and molecular biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R. China
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Iron dextran increases hepatic oxidative stress and alters expression of genes related to lipid metabolism contributing to hyperlipidaemia in murine model. BIOMED RESEARCH INTERNATIONAL 2015; 2015:272617. [PMID: 25685776 PMCID: PMC4313725 DOI: 10.1155/2015/272617] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 09/17/2014] [Accepted: 09/25/2014] [Indexed: 01/28/2023]
Abstract
The objective of this study was to investigate the effects of iron dextran on lipid metabolism and to determine the involvement of oxidative stress. Fischer rats were divided into two groups: the standard group (S), which was fed the AIN-93M diet, and the standard plus iron group (SI), which was fed the same diet but also received iron dextran injections. Serum cholesterol and triacylglycerol levels were higher in the SI group than in the S group. Iron dextran was associated with decreased mRNA levels of pparα, and its downstream gene cpt1a, which is involved in lipid oxidation. Iron dextran also increased mRNA levels of apoB-100, MTP, and L-FABP indicating alterations in lipid secretion. Carbonyl protein and TBARS were consistently higher in the liver of the iron-treated rats. Moreover, a significant positive correlation was found between oxidative stress products, lfabp expression, and iron stores. In addition, a negative correlation was found between pparα expression, TBARS, carbonyl protein, and iron stores. In conclusion, our results suggest that the increase observed in the transport of lipids in the bloodstream and the decreased fatty acid oxidation in rats, which was promoted by iron dextran, might be attributed to increased oxidative stress.
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Hooper AJ, Burnett JR, Watts GF. Contemporary Aspects of the Biology and Therapeutic Regulation of the Microsomal Triglyceride Transfer Protein. Circ Res 2015; 116:193-205. [DOI: 10.1161/circresaha.116.304637] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Amanda J. Hooper
- Department of Clinical Biochemistry, PathWest Laboratory Medicine WA (A.J.H., J.R.B.), School of Medicine and Pharmacology (A.J.H., J.R.B., G.F.W.), School of Pathology and Laboratory Medicine (A.J.H), and Lipid Disorders Clinic, Cardiovascular Medicine (J.R.B., G.F.W), Royal Perth Hospital, University of Western Australia, Perth, Western Australia, Australia
| | - John R. Burnett
- Department of Clinical Biochemistry, PathWest Laboratory Medicine WA (A.J.H., J.R.B.), School of Medicine and Pharmacology (A.J.H., J.R.B., G.F.W.), School of Pathology and Laboratory Medicine (A.J.H), and Lipid Disorders Clinic, Cardiovascular Medicine (J.R.B., G.F.W), Royal Perth Hospital, University of Western Australia, Perth, Western Australia, Australia
| | - Gerald F. Watts
- Department of Clinical Biochemistry, PathWest Laboratory Medicine WA (A.J.H., J.R.B.), School of Medicine and Pharmacology (A.J.H., J.R.B., G.F.W.), School of Pathology and Laboratory Medicine (A.J.H), and Lipid Disorders Clinic, Cardiovascular Medicine (J.R.B., G.F.W), Royal Perth Hospital, University of Western Australia, Perth, Western Australia, Australia
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28
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Levy E. Insights from human congenital disorders of intestinal lipid metabolism. J Lipid Res 2014; 56:945-62. [PMID: 25387865 DOI: 10.1194/jlr.r052415] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Indexed: 12/24/2022] Open
Abstract
The intestine must challenge the profuse daily flux of dietary fat that serves as a vital source of energy and as an essential component of cell membranes. The fat absorption process takes place in a series of orderly and interrelated steps, including the uptake and translocation of lipolytic products from the brush border membrane to the endoplasmic reticulum, lipid esterification, Apo synthesis, and ultimately the packaging of lipid and Apo components into chylomicrons (CMs). Deciphering inherited disorders of intracellular CM elaboration afforded new insight into the key functions of crucial intracellular proteins, such as Apo B, microsomal TG transfer protein, and Sar1b GTPase, the defects of which lead to hypobetalipoproteinemia, abetalipoproteinemia, and CM retention disease, respectively. These "experiments of nature" are characterized by fat malabsorption, steatorrhea, failure to thrive, low plasma levels of TGs and cholesterol, and deficiency of liposoluble vitamins and essential FAs. After summarizing and discussing the functions and regulation of these proteins for reader's comprehension, the current review focuses on their specific roles in malabsorptions and dyslipidemia-related intestinal fat hyperabsorption while dissecting the spectrum of clinical manifestations and managements. The influence of newly discovered proteins (proprotein convertase subtilisin/kexin type 9 and angiopoietin-like 3 protein) on fat absorption has also been provided. Finally, it is stressed how the overexpression or polymorphism status of the critical intracellular proteins promotes dyslipidemia and cardiometabolic disorders.
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Affiliation(s)
- Emile Levy
- Research Centre, CHU Sainte-Justine and Department of Nutrition, Université de Montréal, Montreal, Quebec H3T 1C5, Canada
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Saad Y, Shaker O, Nassar Y, Ahmad L, Said M, Esmat G. A polymorphism in the microsomal triglyceride transfer protein can predict the response to antiviral therapy in Egyptian patients with chronic hepatitis C virus genotype 4 infection. Gut Liver 2014; 8:655-61. [PMID: 25287167 PMCID: PMC4215453 DOI: 10.5009/gnl13374] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 01/06/2014] [Accepted: 01/18/2014] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND/AIMS A polymorphism in the microsomal triglyceride transfer protein (MTP) is associated with hepatic fibrosis, and carriers showed higher levels of steatosis, higher levels of hepatitis C virus (HCV) RNA and advanced fibrosis. The aim of this study was to study MTP expression pattern in HCV patients and impact of the MTP polymorphism on the response to antiviral therapy. METHODS One hundred consecutive naive HCV genotype 4 patients were recruited to receive antiviral therapy, and 40 control subjects were also recruited. Demographic, laboratory, and histopathology data were collected. DNA was isolated, and the samples were subjected to polymerase chain reaction analysis and genotyping for MTP by restriction fragment length polymorphism analysis. RESULTS Patients and controls were age- and sex-matched (male/female, 56/44, age, 39.2±7.8 years for patients with HCV; male/female, 18/22, age, 38.1±8.1 years for controls). MTP single nucleotide polymorphisms (SNPs) (GG, GT, TT) and alleles (G, T) in the patients versus the controls were 70%, 21%, 9% & 80.5%, 19.5% versus 10%, 87.5%, 2.5% & 53.8%, 46.3%, respectively (p=0.0001). The sustained viral response (SVR) of the patients was 60%. SNPs in MTP genotypes (GG, GT, and TT) and alleles (G and T) in the responders and nonresponders were 71.7%, 25%, 3.3% & 84.2%, 15.8% versus 67.5%, 15%, 17.5% & 75%, 25% (p=0.038 and p=0.109, respectively). A multivariate analysis showed that the GT genotype was an independent predictor of SVR (area under the curve 90% and p=0.0001). CONCLUSIONS MTP could be a new predictor for SVR to antiviral therapy in patients with HCV genotype 4 infection.
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Affiliation(s)
- Yasmin Saad
- Departments of Endemic Medicine and Hepatogastroenterology and Biochemistry, Cairo University Faculty of Medicine, Cairo, Egypt
| | - Olfat Shaker
- Departments of Endemic Medicine and Hepatogastroenterology and Biochemistry, Cairo University Faculty of Medicine, Cairo, Egypt
| | - Yasser Nassar
- Departments of Endemic Medicine and Hepatogastroenterology and Biochemistry, Cairo University Faculty of Medicine, Cairo, Egypt
| | - Lama Ahmad
- Departments of Endemic Medicine and Hepatogastroenterology and Biochemistry, Cairo University Faculty of Medicine, Cairo, Egypt
| | - Mohamed Said
- Departments of Endemic Medicine and Hepatogastroenterology and Biochemistry, Cairo University Faculty of Medicine, Cairo, Egypt
| | - Gamal Esmat
- Departments of Endemic Medicine and Hepatogastroenterology and Biochemistry, Cairo University Faculty of Medicine, Cairo, Egypt
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Xiao CW, Donak K, Ly O, Wood C, Cooke G, Curran I. Dietary soy isoflavones increased hepatic protein disulfide isomerase content and suppressed its enzymatic activity in rats. Exp Biol Med (Maywood) 2014; 239:707-14. [PMID: 24676904 DOI: 10.1177/1535370214527902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Protein disulfide isomerase (PDI) is a multifunctional protein and plays important roles in protein folding, triglyceride transfer, insulin degradation, and thyroid hormone transportation. This study examined the modulation of PDI expression by soy consumption using rat as a model. Sprague-Dawley male and female rats at 50 days (d) of age were fed diets containing either 20% casein or alcohol-washed soy protein isolate (SPI, containing 50 mg isoflavones (ISFs)/kg diet) or SPI plus ISF (250 mg/kg diet) and mated at age of 120 d. The offspring (F1) were fed the same diets as their parents. Addition of ISF to SPI diet markedly increased PDI protein content in the liver and testis of the adult rats compared with the casein or SPI diet. PDI mRNA abundance in the liver and protein content in the brain, thyroid, heart, and uterus were unchanged by the diets. Two-dimensional Western blot showed that the rats fed diets containing SPI had a diminished hepatic PDI protein with an isoelectric point (pI) of 6.12, a dephosphorylated form, compared with the rats fed diets containing either casein or SPI with supplemental ISF. Soy ISF added into SPI diet remarkably suppressed hepatic PDI activity of the rats compared with the casein diet. Moreover, soy ISF dose-dependently increased PDI and thyroid hormone receptor (TR) β protein content, whereas reduced TR DNA binding ability in human hepatocytes. Overall, this study shows that soy ISF increased hepatic PDI protein content, but addition of ISF into SPI diet inhibited its enzymatic activities and this effect may be mediated through a post-transcriptional mechanism.
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31
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Stefanutti C. Targeting MTP for the treatment of homozygous familial hypercholesterolemia. ACTA ACUST UNITED AC 2014. [DOI: 10.2217/clp.14.17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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32
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Molecular characterization and expression profiling of the protein disulfide isomerase gene family in Brachypodium distachyon L. PLoS One 2014; 9:e94704. [PMID: 24747843 PMCID: PMC3991636 DOI: 10.1371/journal.pone.0094704] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 03/17/2014] [Indexed: 01/09/2023] Open
Abstract
Protein disulfide isomerases (PDI) are involved in catalyzing protein disulfide bonding and isomerization in the endoplasmic reticulum and functions as a chaperone to inhibit the aggregation of misfolded proteins. Brachypodium distachyon is a widely used model plant for temperate grass species such as wheat and barley. In this work, we report the first molecular characterization, phylogenies, and expression profiles of PDI and PDI-like (PDIL) genes in B. distachyon in different tissues under various abiotic stresses. Eleven PDI and PDIL genes in the B. distachyon genome by in silico identification were evenly distributed across all five chromosomes. The plant PDI family has three conserved motifs that are involved in catalyzing protein disulfide bonding and isomerization, but a different exon/intron structural organization showed a high degree of structural differentiation. Two pairs of genes (BdPDIL4-1 and BdPDIL4-2; BdPDIL7-1 and BdPDIL7-2) contained segmental duplications, indicating each pair originated from one progenitor. Promoter analysis showed that Brachypodium PDI family members contained important cis-acting regulatory elements involved in seed storage protein synthesis and diverse stress response. All Brachypodium PDI genes investigated were ubiquitously expressed in different organs, but differentiation in expression levels among different genes and organs was clear. BdPDIL1-1 and BdPDIL5-1 were expressed abundantly in developing grains, suggesting that they have important roles in synthesis and accumulation of seed storage proteins. Diverse treatments (drought, salt, ABA, and H2O2) induced up- and down-regulated expression of Brachypodium PDI genes in seedling leaves. Interestingly, BdPDIL1-1 displayed significantly up-regulated expression following all abiotic stress treatments, indicating that it could be involved in multiple stress responses. Our results provide new insights into the structural and functional characteristics of the plant PDI gene family.
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Miyake Y, Hashimoto S, Sasaki Y, Kudo T, Oguro A, Imaoka S. Endoplasmic reticulum protein (ERp) 29 binds as strongly as protein disulfide isomerase (PDI) to bisphenol A. Chem Res Toxicol 2014; 27:501-6. [PMID: 24512454 DOI: 10.1021/tx400357q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bisphenol A (BPA), which is used in polycarbonate and epoxy resins, affects the development or function of the central nervous system. Previously, we isolated a BPA-binding protein from rat brain, identified it as protein disulfide isomerase (PDI), and found that BPA binds to the b' domain of PDI and inhibits its activity. There are 20 kinds of PDI family proteins in mammalian endoplasmic reticulum. The member proteins each have a different length and domain arrangement. Here we investigated the binding of BPA and T3 to ERp29, ERp57, and ERp72, which each have the b or b' domain. BPA/T3 binding of ERp57 and that of ERp72 were lower than that of PDI, and BPA did not inhibit the oxidase or reductase activity of these proteins. On the other hand, BPA and T3 bound to ERp29 as strongly as to PDI. The CD spectrum of PDI was changed in the presence of BPA in a dose-dependent manner, while that of ERp29 was not, suggesting that BPA did not affect the conformation of ERp29. We found that PDI suppresses GH expression in rat GH3 cells stimulated by thyroid hormone (T3) overexpression of PDI and that ERp57 reduced the GH level, but overexpression of ERp29 did not change GH expression. These results suggested that affinity to T3 does not involve the reduction of the T3 response. In this study, ERp29 was first identified as a BPA-binding protein but is not involved in the T3 response of GH3 cells.
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Affiliation(s)
- Yuka Miyake
- Research Center for Environmental Bioscience and Department of Bioscience, School of Science and Technology, Kwansei Gakuin University , 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan
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Salter AM, White DA. Effects of Dietary Fat on Cholesterol Metabolism: Regulation of Plasma LDL Concentrations. Nutr Res Rev 2013; 9:241-57. [PMID: 19094272 DOI: 10.1079/nrr19960013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- A M Salter
- Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington Campus, Loughborough, Leics LE12 5RD
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Tateya S, Rizzo-De Leon N, Handa P, Cheng AM, Morgan-Stevenson V, Ogimoto K, Kanter JE, Bornfeldt KE, Daum G, Clowes AW, Chait A, Kim F. VASP increases hepatic fatty acid oxidation by activating AMPK in mice. Diabetes 2013; 62:1913-22. [PMID: 23349495 PMCID: PMC3661609 DOI: 10.2337/db12-0325] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Activation of AMP-activated protein kinase (AMPK) signaling reduces hepatic steatosis and hepatic insulin resistance; however, its regulatory mechanisms are not fully understood. In this study, we sought to determine whether vasodilator-stimulated phosphoprotein (VASP) signaling improves lipid metabolism in the liver and, if so, whether VASP's effects are mediated by AMPK. We show that disruption of VASP results in significant hepatic steatosis as a result of significant impairment of fatty acid oxidation, VLDL-triglyceride (TG) secretion, and AMPK signaling. Overexpression of VASP in hepatocytes increased AMPK phosphorylation and fatty acid oxidation and reduced hepatocyte TG accumulation; however, these responses were suppressed in the presence of an AMPK inhibitor. Restoration of AMPK phosphorylation by administration of 5-aminoimidazole-4-carboxamide riboside in Vasp(-/-) mice reduced hepatic steatosis and normalized fatty acid oxidation and VLDL-TG secretion. Activation of VASP by the phosphodiesterase-5 inhibitor, sildenafil, in db/db mice reduced hepatic steatosis and increased phosphorylated (p-)AMPK and p-acetyl CoA carboxylase. In Vasp(-/-) mice, however, sildendafil treatment did not increase p-AMPK or reduce hepatic TG content. These studies identify a role of VASP to enhance hepatic fatty acid oxidation by activating AMPK and to promote VLDL-TG secretion from the liver.
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Affiliation(s)
- Sanshiro Tateya
- Department of Medicine, University of Washington, Seattle, Washington, USA.
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Kato T, Thompson JR, Park EY. Construction of new ligation-independent cloning vectors for the expression and purification of recombinant proteins in silkworms using BmNPV bacmid system. PLoS One 2013; 8:e64007. [PMID: 23675518 PMCID: PMC3651184 DOI: 10.1371/journal.pone.0064007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 04/08/2013] [Indexed: 11/21/2022] Open
Abstract
A ligation independent cloning (LIC) system has been developed to facilitate the rapid and high-efficiency cloning of genes in a Bombyx mori expression system. This system was confirmed by the expression of human microsomal triglyceride transfer protein (hMTP) fused with EGFP in silkworm larvae and pupae. Moreover, hMTP and human protein disulfide isomerase (hPDI) genes were inserted into two LIC vectors harboring gcLINK sequences and were combined by using the LIC through gcLINK sequences. The constructed vector was incorporated into the Bombyx mori nucleopolyhedrovirus (BmNPV) bacmid, and injected into silkworm larvae. The expressed hMTP-hPDI complex was purified from the fat bodies of silkworm larvae. This LIC vector system was applied to express the E1, E2, and E3 subunits of human α-ketoglutarate dehydrogenase (KGDH) in silkworm larvae. The expressed proteins were purified easily from fat bodies using three different affinity chromatography steps. The LIC vectors constructed as described in this report allow for the rapid expression and purification of recombinant proteins or their complexes by using the BmNPV bacmid system.
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Affiliation(s)
- Tatsuya Kato
- Laboratory of Biotechnology, Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, Suruga-ku, Shizuoka, Japan
| | - James R. Thompson
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota, United States of America
| | - Enoch Y. Park
- Laboratory of Biotechnology, Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, Suruga-ku, Shizuoka, Japan
- Laboratory of Biotechnology, Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Suruga-ku, Shizuoka, Japan
- Laboratory of Biotechnology, Research Institute of Green Science and Technology, Shizuoka University, Suruga-ku, Shizuoka, Japan
- * E-mail:
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Khatun I, Walsh MT, Hussain MM. Loss of both phospholipid and triglyceride transfer activities of microsomal triglyceride transfer protein in abetalipoproteinemia. J Lipid Res 2013; 54:1541-1549. [PMID: 23475612 DOI: 10.1194/jlr.m031658] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutations in microsomal triglyceride transfer protein (MTP) cause abetalipoproteinemia (ABL), characterized by the absence of plasma apoB-containing lipoproteins. In this study, we characterized the effects of various MTP missense mutations found in ABL patients with respect to their expression, subcellular location, and interaction with protein disulfide isomerase (PDI). In addition, we characterized functional properties by analyzing phospholipid and triglyceride transfer activities and studied their ability to support apoB secretion. All the mutants colocalized with calnexin and interacted with PDI. We found that R540H and N780Y, known to be deficient in triglyceride transfer activity, also lacked phospholipid transfer activity. Novel mutants S590I and G746E did not transfer triglycerides and phospholipids and did not assist in apoB secretion. In contrast, D384A displayed both triglyceride and phospholipid transfer activities and supported apoB secretion. These studies point out that ABL is associated with the absence of both triglyceride and phospholipid transfer activities in MTP.
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Affiliation(s)
- Irani Khatun
- Molecular and Cellular Biology Program, SUNY Downstate Medical Center, Brooklyn, NY; School of Graduate Studies, Department of Cell Biology, and SUNY Downstate Medical Center, Brooklyn, NY; Department of Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY
| | - Meghan T Walsh
- Molecular and Cellular Biology Program, SUNY Downstate Medical Center, Brooklyn, NY; School of Graduate Studies, Department of Cell Biology, and SUNY Downstate Medical Center, Brooklyn, NY; Department of Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY
| | - M Mahmood Hussain
- School of Graduate Studies, Department of Cell Biology, and SUNY Downstate Medical Center, Brooklyn, NY; Department of Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY.
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Lehner R, Lian J, Quiroga AD. Lumenal lipid metabolism: implications for lipoprotein assembly. Arterioscler Thromb Vasc Biol 2012; 32:1087-93. [PMID: 22517367 DOI: 10.1161/atvbaha.111.241497] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Overproduction of apolipoprotein B (apoB)-containing lipoproteins by the liver and the intestine is 1 of the hallmarks of insulin resistance and type 2 diabetes and a well-established risk factor of cardiovascular disease. The assembly of apoB lipoproteins is regulated by the availability of lipids that form the neutral lipid core (triacylglycerol and cholesteryl ester) and the limiting lipoprotein monolayer (phospholipids and cholesterol). Although tremendous advances have been made over the past decade toward understanding neutral lipid and phospholipid biosynthesis and neutral lipid storage in cytosolic lipid droplets (LDs), little is known about the mechanisms that govern the transfer of lipids to the lumen of the endoplasmic reticulum for apoB lipidation. ApoB-synthesizing organs can deposit synthesized neutral lipids into at least 3 different types of LDs, each decorated with a subset of specific proteins: perilipin-decorated cytosolic LDs, and 2 types of LDs formed in the lumen of the endoplasmic reticulum, the secretion-destined LDs containing apoB, and resident lumenal LDs coated with microsomal triglyceride transfer protein and exchangeable apolipoproteins. This brief review will address the current knowledge of lumenal lipid metabolism in the context of apoB assembly and lipid storage.
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Affiliation(s)
- Richard Lehner
- Department of Pediatrics and Cell Biology, Group on Molecular and Cell Biology of Lipids, University of Alberta, Edmonton, Alberta, Canada.
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Galligan JJ, Petersen DR. The human protein disulfide isomerase gene family. Hum Genomics 2012; 6:6. [PMID: 23245351 PMCID: PMC3500226 DOI: 10.1186/1479-7364-6-6] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 05/14/2012] [Indexed: 01/27/2023] Open
Abstract
Enzyme-mediated disulfide bond formation is a highly conserved process affecting over one-third of all eukaryotic proteins. The enzymes primarily responsible for facilitating thiol-disulfide exchange are members of an expanding family of proteins known as protein disulfide isomerases (PDIs). These proteins are part of a larger superfamily of proteins known as the thioredoxin protein family (TRX). As members of the PDI family of proteins, all proteins contain a TRX-like structural domain and are predominantly expressed in the endoplasmic reticulum. Subcellular localization and the presence of a TRX domain, however, comprise the short list of distinguishing features required for gene family classification. To date, the PDI gene family contains 21 members, varying in domain composition, molecular weight, tissue expression, and cellular processing. Given their vital role in protein-folding, loss of PDI activity has been associated with the pathogenesis of numerous disease states, most commonly related to the unfolded protein response (UPR). Over the past decade, UPR has become a very attractive therapeutic target for multiple pathologies including Alzheimer disease, Parkinson disease, alcoholic and non-alcoholic liver disease, and type-2 diabetes. Understanding the mechanisms of protein-folding, specifically thiol-disulfide exchange, may lead to development of a novel class of therapeutics that would help alleviate a wide range of diseases by targeting the UPR.
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Affiliation(s)
- James J Galligan
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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Park S, Lee J. Proteome profile changes in SH-SY5y neuronal cells after treatment with neurotrophic factors. J Cell Biochem 2012; 112:3845-55. [PMID: 21826712 DOI: 10.1002/jcb.23316] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Artemin, one of glial cell line-derived neurotrophic factors (GDNFs) supports sensory neuron. Although a role of artemin and GDNF as neurite outgrowth regulators in early neuron development has been suggested, the immediate effects of artemin and GDNF on neuronal cells have not been elucidated. Here, we investigated artemin and GDNF actions on the neuronal cell proteome. To identify immediate-early protein changes by artemin and GDNF in neuronal cells, we used a differential proteomics approach in SH-SY5y human neuronal cells treated with artemin or GDNF for 1 h. Eleven proteins that changed after both artemin and GDNF treatment were identified using two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight tandem mass spectroscopy. The calcium ion-binding chaperone calreticulin and calcium/calmodulin-binding nuclear matrix protein matrin 3 showed common quantitative differences after both artemin and GDNF treatment. Cytoskeletal proteins also showed quantitative profile differences, which are functionally relevant to cytoskeletal rearrangement leading to the neurite elongation in neurons. These protein changes were detected in neuronal cells without accompanying changes in mRNA levels. These results suggest that immediate changes induced by artemin and GDNF are related to cytoskeletal protein level changes without transcriptional regulation.
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Affiliation(s)
- Seyeon Park
- Department of Applied Chemistry, Dongduk Women's University, Seoul 136-714, Korea.
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Wang C, Yu J, Huo L, Wang L, Feng W, Wang CC. Human protein-disulfide isomerase is a redox-regulated chaperone activated by oxidation of domain a'. J Biol Chem 2011; 287:1139-49. [PMID: 22090031 DOI: 10.1074/jbc.m111.303149] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein-disulfide isomerase (PDI), with domains arranged as abb'xa'c, is a key enzyme and chaperone localized in the endoplasmic reticulum (ER) catalyzing oxidative folding and preventing misfolding/aggregation of proteins. It has been controversial whether the chaperone activity of PDI is redox-regulated, and the molecular basis is unclear. Here, we show that both the chaperone activity and the overall conformation of human PDI are redox-regulated. We further demonstrate that the conformational changes are triggered by the active site of domain a', and the minimum redox-regulated cassette is located in b'xa'. The structure of the reduced bb'xa' reveals for the first time that domain a' packs tightly with both domain b' and linker x to form one compact structural module. Oxidation of domain a' releases the compact conformation and exposes the shielded hydrophobic areas to facilitate its high chaperone activity. Thus, the study unequivocally provides mechanistic insights into the redox-regulated chaperone activity of human PDI.
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Affiliation(s)
- Chao Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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Kulkarni SD, Muralidharan B, Panda AC, Bakthavachalu B, Vindu A, Seshadri V. Glucose-stimulated translation regulation of insulin by the 5' UTR-binding proteins. J Biol Chem 2011; 286:14146-56. [PMID: 21357685 DOI: 10.1074/jbc.m110.190553] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin is the key regulator of glucose homeostasis in mammals, and glucose-stimulated insulin biosynthesis is essential for maintaining glucose levels in a narrow range in mammals. Glucose specifically promotes the translation of insulin in pancreatic β-islet, and the untranslated regions of insulin mRNA play a role in such regulation. Specific factors in the β-islets bind to the insulin 5' UTR and regulate its translation. In the present study we identify protein-disulfide isomerase (PDI) as a key regulator of glucose-stimulated insulin biosynthesis. We show that both in vitro and in vivo PDI can specifically associate with the 5' UTR of insulin mRNA. Immunodepletion of PDI from the islet extract results in loss of glucose-stimulated translation indicating a critical role for PDI in insulin biosynthesis. Similarly, transient overexpression of PDI resulted in specific translation activation by glucose. We show that the RNA binding activity of PDI is mediated through PABP. PDI catalyzes the reduction of the PABP disulfide bond resulting in specific binding of PABP to the insulin 5' UTR. We also show that glucose stimulation of the islets results in activation of a specific kinase that can phosphorylate PDI. These findings identify PDI and PABP as important players in glucose homeostasis.
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Abstract
IMPORTANCE OF THE FIELD Elevated concentrations of low-density lipoprotein (LDL) cholesterol are associated with increased risk of coronary atherosclerosis, and morbidity and mortality from coronary heart disease (CHD). Lowering of LDL cholesterol leads to a reduction in cardiovascular morbidity and all-cause mortality in individuals at risk for cardiovascular events and patients with established CHD. The mainstays of lipid lowering therapy today are the HMG-CoA reductase inhibitors (statins); however, the residual risk of cardiovascular events amongst individuals treated with statins remains a major healthcare concern. AREAS COVERED IN THIS REVIEW Emerging targets for lipid lowering therapy target pathways that regulate lipoprotein assembly, lipoprotein clearance and pro-atherogenic lipoprotein modification. These emerging drugs have novel mechanisms that include inhibition of lipoprotein assembly (antisense mRNA inhibitors of apolipoprotein B and microsomal transfer protein inhibitors), enhanced lipoprotein clearance (proprotein convertase subtilisin kexin type 9, thyroid hormone analogues), inhibition of pro-atherogenic lipoprotein remodeling (cholesterol ester transfer protein inhibitors (dalcetrapib, anacetrapib) and peroxisome proliferator activator agents (GFT-505, aleglitazar)) and inhibition of lipoprotein modification (heme oxygenase-1 inhibitor (succinobucol), phospholipase A(2) inhibitors (varespladib, darapladib)). WHAT THE READER WILL GAIN A review of the most recent data on emerging drugs in the treatment of hyperlipidemia. TAKE HOME MESSAGE With these medications, we will achieve more effective reductions in cardiovascular morbidity and mortality than achieved with current lipid lowering therapies.
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Kozlov G, Määttänen P, Thomas DY, Gehring K. A structural overview of the PDI family of proteins. FEBS J 2010; 277:3924-36. [DOI: 10.1111/j.1742-4658.2010.07793.x] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Human pancreas-specific protein disulfide-isomerase (PDIp) can function as a chaperone independently of its enzymatic activity by forming stable complexes with denatured substrate proteins. Biochem J 2010; 429:157-69. [PMID: 20423326 DOI: 10.1042/bj20091954] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Members of the PDI (protein disulfide-isomerase) family are critical for the correct folding of secretory proteins by catalysing disulfide bond formation as well as by serving as molecular chaperones to prevent protein aggregation. In the present paper, we report that the chaperone activity of the human pancreas-specific PDI homologue (PDIp) is independent of its enzymatic activity on the basis of the following lines of evidence. First, alkylation of PDIp by iodoacetamide fully abolishes its enzymatic activity, whereas it still retains most of its chaperone activity in preventing the aggregation of reduced insulin B chain and denatured GAPDH (glyceraldehyde-3-phosphate dehydrogenase). Secondly, mutation of the cysteine residues in PDIp's active sites completely abolishes its enzymatic activity, but does not affect its chaperone activity. Thirdly, the b-b' fragment of PDIp, which does not contain the active sites and is devoid of enzymatic activity, still has chaperone activity. Mechanistically, we found that both the recombinant PDIp expressed in Escherichia coli and the natural PDIp present in human or monkey pancreas can form stable complexes with thermal-denatured substrate proteins independently of their enzymatic activity. The high-molecular-mass soluble complexes between PDIp and GAPDH are formed in a stoichiometric manner (subunit ratio of 1:3.5-4.5), and can dissociate after storage for a certain time. As a proof-of-concept for the biological significance of PDIp in intact cells, we demonstrated that its selective expression in E. coli confers strong protection of these cells against heat shock and oxidative-stress-induced death independently of its enzymatic activity.
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d'Aloisio E, Paolacci AR, Dhanapal AP, Tanzarella OA, Porceddu E, Ciaffi M. The Protein Disulfide Isomerase gene family in bread wheat (T. aestivum L.). BMC PLANT BIOLOGY 2010; 10:101. [PMID: 20525253 PMCID: PMC3017771 DOI: 10.1186/1471-2229-10-101] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Accepted: 06/03/2010] [Indexed: 05/20/2023]
Abstract
BACKGROUND The Protein Disulfide Isomerase (PDI) gene family encodes several PDI and PDI-like proteins containing thioredoxin domains and controlling diversified metabolic functions, including disulfide bond formation and isomerisation during protein folding. Genomic, cDNA and promoter sequences of the three homologous wheat genes encoding the "typical" PDI had been cloned and characterized in a previous work. The purpose of present research was the cloning and characterization of the complete set of genes encoding PDI and PDI like proteins in bread wheat (Triticum aestivum cv Chinese Spring) and the comparison of their sequence, structure and expression with homologous genes from other plant species. RESULTS Eight new non-homologous wheat genes were cloned and characterized. The nine PDI and PDI-like sequences of wheat were located in chromosome regions syntenic to those in rice and assigned to eight plant phylogenetic groups. The nine wheat genes differed in their sequences, genomic organization as well as in the domain composition and architecture of their deduced proteins; conversely each of them showed high structural conservation with genes from other plant species in the same phylogenetic group. The extensive quantitative RT-PCR analysis of the nine genes in a set of 23 wheat samples, including tissues and developmental stages, showed their constitutive, even though highly variable expression. CONCLUSIONS The nine wheat genes showed high diversity, while the members of each phylogenetic group were highly conserved even between taxonomically distant plant species like the moss Physcomitrella patens. Although constitutively expressed the nine wheat genes were characterized by different expression profiles reflecting their different genomic organization, protein domain architecture and probably promoter sequences; the high conservation among species indicated the ancient origin and diversification of the still evolving gene family. The comprehensive structural and expression characterization of the complete set of PDI and PDI-like wheat genes represents a basis for the functional characterization of this gene family in the hexaploid context of bread wheat.
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Affiliation(s)
- Elisa d'Aloisio
- Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy
| | - Anna R Paolacci
- Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, Via S. Camillo De Lellis, 01100 Viterbo, Italy
| | - Arun P Dhanapal
- Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy
| | - Oronzo A Tanzarella
- Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, Via S. Camillo De Lellis, 01100 Viterbo, Italy
| | - Enrico Porceddu
- Scuola Superiore Sant'Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy
- Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, Via S. Camillo De Lellis, 01100 Viterbo, Italy
| | - Mario Ciaffi
- Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, Via S. Camillo De Lellis, 01100 Viterbo, Italy
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Targett-Adams P, Boulant S, Douglas MW, McLauchlan J. Lipid metabolism and HCV infection. Viruses 2010; 2:1195-1217. [PMID: 21994676 PMCID: PMC3187597 DOI: 10.3390/v2051195] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 05/05/2010] [Accepted: 05/06/2010] [Indexed: 12/15/2022] Open
Abstract
Chronic infection by hepatitis C virus (HCV) can lead to severe liver disease and is a global healthcare problem. The liver is highly metabolically active and one of its key functions is to control the balance of lipid throughout the body. A number of pathologies have been linked to the impact of HCV infection on liver metabolism. However, there is also growing evidence that hepatic metabolic processes contribute to the HCV life cycle. This review summarizes the relationship between lipid metabolism and key stages in the production of infectious HCV.
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Affiliation(s)
- Paul Targett-Adams
- Pfizer Global Research & Development, Infectious Diseases Group, Sandwich Laboratories, Sandwich, CT13 9NJ, UK; E-Mail:
| | - Steeve Boulant
- Immune Disease Institute, Harvard Medical School, Department of Microbiology and Molecular Genetics, Boston, MA 02115, USA; E-Mail:
| | - Mark W. Douglas
- Storr Liver Unit, Westmead Millennium Institute, University of Sydney at Westmead Hospital, PO Box 412, Westmead, NSW 2145, Australia; E-Mail:
| | - John McLauchlan
- MRC Virology Unit, Church Street, Glasgow G11 5JR, UK
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +44-141-330-4028; Fax: +44-141-330-3520
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Wolff E, Vergnes MF, Defoort C, Planells R, Portugal H, Nicolay A, Lairon D. Cholesterol absorption status and fasting plasma cholesterol are modulated by the microsomal triacylglycerol transfer protein -493 G/T polymorphism and the usual diet in women. GENES AND NUTRITION 2010; 6:71-9. [PMID: 21437032 DOI: 10.1007/s12263-010-0174-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 03/15/2010] [Indexed: 12/29/2022]
Abstract
An important inter-individual variability in cholesterol absorption has been reported. It could result from polymorphisms in genes coding for proteins involved in the absorption process and in interaction with dietary intakes. To assess whether the extent of cholesterol absorption or synthesis is modified in adult women according to the -493 G/T polymorphism in the microsomal triglyceride transfer protein gene (MTP) and/or the habitual diet. Cholestanol and sitosterol, as well as desmosterol and lathosterol, surrogate markers of cholesterol absorption or synthesis, respectively, were analyzed in the fasting plasma of 69 middle-aged women under a Western-type diet (WD) and after 3 months on a low-saturated fat, low-cholesterol/Mediterranean-type diet (LFLCD). Genotypes for MTP -493G/T polymorphism were determined. Under an usual WD, subjects homozygous for the MTP -493 T allele exhibited higher (P < 0.05) fasting serum concentrations of cholestanol (199.0 ± 30.0 vs. 133 ± 7.4 × 10(2 )mmol/mol cholesterol) and lathosterol (188.7 ± 21.8 vs. 147.6 ± 9.1 × 10(2) mmol/mol cholesterol), as well as total cholesterol (7.32 ± 0.22 vs. 6.63 ± 0.12 mmol/l) compared to G carrier subjects. After 3 months on a LFLCD, level of absorption markers decreased in TT subjects with no change in synthesis ones, leading to values comparable to those measured in G carriers. The lowering of plasma total and LDL cholesterol due to dietary change was 2.4- and 2.3-fold greater in TT women than in G carriers. The polymorphism -493G/T in MTP modulates the level of cholesterol absorption but not synthesis in women under a WD, an effect abolished under a prudent LFLCD.
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Costet P. Molecular pathways and agents for lowering LDL-cholesterol in addition to statins. Pharmacol Ther 2010; 126:263-78. [PMID: 20227438 DOI: 10.1016/j.pharmthera.2010.02.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 02/09/2010] [Indexed: 01/07/2023]
Abstract
Recent guidelines in North America and Europe recommend lowering low density lipoprotein associated cholesterol (LDLC) to achieve optimal coronary heart disease risk reduction. Statins have been the therapy of choice and proven successful and relatively safe. However, we are now facing new challenges and it appears that additional or alternative drugs are urgently needed. This boosts research in the field, reopening old cases like other inhibitors of cholesterol synthesis or making attractive tools from the latest technologies like gene silencing by anti-sense oligonucleotides. LDLs are cholesterol-enriched lipoproteins stabilized by the hepatic apolipoprotein B100, and derived from TG rich very low density lipoprotein. This review focuses on the molecular pathways involved in plasma LDLC production and elimination, in particular cholesterol absorption and the hepatobiliary route, apoB100 and VLDL production, and LDL clearance via the LDL receptor. We will identify important or rate-limiting proteins (including Niemann-Pick C1-like 1 (NPC1L1), microsomal TG transfer protein (MTP), acyl-coenzyme A/cholesterol acyltransferase (ACAT), Acyl-CoA:diacylglycerol acyltransferases 2 (DGAT2), proprotein convertase subtilisin kexin type 9 (PCSK9)), and nuclear receptors (farnesoid X receptor (FXR), thyroid hormone receptor (TR)) that constitute interesting therapeutic targets. Numerous compounds already in use modulate these pathways, such as phytosterols, ezetimibe, bile acids sequestrants, niacin, and fibrates. Many pathways can be considered to lower LDLC, but the road has been paved with disappointments and difficulties. With new targets identified and diversification of the drugs, a new era for better LDLC management is plausible.
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Peng SE, Wang YB, Wang LH, Chen WNU, Lu CY, Fang LS, Chen CS. Proteomic analysis of symbiosome membranes in Cnidaria-dinoflagellate endosymbiosis. Proteomics 2010; 10:1002-16. [DOI: 10.1002/pmic.200900595] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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