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Jaliliyan A, Madankan A, Mosavari H, Khalili P, Pouraskari B, Lotfi S, Honarfar A, Fakhri E, Eghbali F. The Impact of Metabolic and Bariatric Surgery on Apo B100 Levels in Individuals with high BMI: A Multi-Centric Prospective Cohort Study. Obes Surg 2024:10.1007/s11695-024-07258-6. [PMID: 38744799 DOI: 10.1007/s11695-024-07258-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 04/19/2024] [Accepted: 04/24/2024] [Indexed: 05/16/2024]
Abstract
BACKGROUND Metabolic and Bariatric surgery (MBS) leads to significant weight loss and improvements in obesity-related comorbidities. However, the impact of MBS on Apolipoprotein B100 (Apo-B100) regulation is unclear. Apo-B100 is essential for the assembly and secretion of serum lipoprotein particles. Elevated levels of these factors can accelerate the development of atherosclerotic plaques in blood vessels. This study aimed to evaluate changes in Apo-B100 levels following MBS. METHODS 121 participants from the Iranian National Obesity and Metabolic Surgery Database (INOSD) underwent Laparoscopic Sleeve Gastrectomy (LSG) (n = 43), One-Anastomosis Gastric Bypass (OAGB) (n = 70) or Roux-en-Y Gastric Bypass (RYGB) (n = 8). Serum Apo-B100, lipid profiles, liver enzymes, and fasting glucose were measured preoperatively and six months postoperatively. RESULTS Apo-B100 levels significantly decreased from 94.63 ± 14.35 mg/dL preoperatively to 62.97 ± 19.97 mg/dL after six months (p < 0.01), alongside reductions in total cholesterol, triglycerides, LDL, VLDL, AST, and ALT (p < 0.05). Greater Apo-B100 reductions occurred in non-diabetics versus people with diabetes (p = 0.012) and strongly correlated with baseline Apo-B100 (r = 0.455, p < 0.01) and LDL levels (r = 0.413, p < 0.01). However, surgery type did not impact Apo-B100 changes in multivariate analysis (p > 0.05). CONCLUSION Bariatric surgery leads to a significant reduction in Apo-B100 levels and improvements in lipid profiles and liver enzymes, indicating a positive impact on dyslipidemia and cardiovascular risk in individuals with high BMI.
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Affiliation(s)
- Ali Jaliliyan
- Department of Surgery, Surgery Research Center, School of Medicine, Rasool-E Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Ahmad Madankan
- Department of Surgery, Surgery Research Center, School of Medicine, Rasool-E Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Hesam Mosavari
- Department of Surgery, Surgery Research Center, School of Medicine, Rasool-E Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Pantea Khalili
- Department of Surgery, Surgery Research Center, School of Medicine, Rasool-E Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Bahador Pouraskari
- Department of Surgery, Surgery Research Center, School of Medicine, Rasool-E Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Saeed Lotfi
- Department of Internal Medicine, Imam Khomeini Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Andia Honarfar
- Department of Surgery, Surgery Research Center, School of Medicine, Rasool-E Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Elham Fakhri
- Department of Surgery, Surgery Research Center, School of Medicine, Rasool-E Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Foolad Eghbali
- Department of Surgery, Surgery Research Center, School of Medicine, Rasool-E Akram Hospital, Iran University of Medical Sciences, Tehran, Iran.
- Department of Surgery, Minimally Invasive Surgery Research Center, Division of Minimally Invasive and Bariatric Surgery, School of Medicine, Rasool-E Akram Hospital, Iran University of Medical Sciences, Tehran, Iran.
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van Zwol W, van de Sluis B, Ginsberg HN, Kuivenhoven JA. VLDL Biogenesis and Secretion: It Takes a Village. Circ Res 2024; 134:226-244. [PMID: 38236950 DOI: 10.1161/circresaha.123.323284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/21/2023] [Indexed: 01/23/2024]
Abstract
The production and secretion of VLDLs (very-low-density lipoproteins) by hepatocytes has a direct impact on liver fat content, as well as the concentrations of cholesterol and triglycerides in the circulation and thus affects both liver and cardiovascular health, respectively. Importantly, insulin resistance, excess caloric intake, and lack of physical activity are associated with overproduction of VLDL, hepatic steatosis, and increased plasma levels of atherogenic lipoproteins. Cholesterol and triglycerides in remnant particles generated by VLDL lipolysis are risk factors for atherosclerotic cardiovascular disease and have garnered increasing attention over the last few decades. Presently, however, increased risk of atherosclerosis is not the only concern when considering today's cardiometabolic patients, as they often also experience hepatic steatosis, a prevalent disorder that can progress to steatohepatitis and cirrhosis. This duality of metabolic risk highlights the importance of understanding the molecular regulation of the biogenesis of VLDL, the lipoprotein that transports triglycerides and cholesterol out of the liver. Fortunately, there has been a resurgence of interest in the intracellular assembly, trafficking, degradation, and secretion of VLDL by hepatocytes, which has led to many exciting new molecular insights that are the topic of this review. Increasing our understanding of the biology of this pathway will aid to the identification of novel therapeutic targets to improve both the cardiovascular and the hepatic health of cardiometabolic patients. This review focuses, for the first time, on this duality.
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Affiliation(s)
- Willemien van Zwol
- Department of Paediatrics, University Medical Center Groningen, University of Groningen, the Netherlands (W.v.Z., B.v.d.S., J.A.K.)
| | - Bart van de Sluis
- Department of Paediatrics, University Medical Center Groningen, University of Groningen, the Netherlands (W.v.Z., B.v.d.S., J.A.K.)
| | - Henry N Ginsberg
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY (H.N.G.)
| | - Jan Albert Kuivenhoven
- Department of Paediatrics, University Medical Center Groningen, University of Groningen, the Netherlands (W.v.Z., B.v.d.S., J.A.K.)
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de Souza CF, Stopa LRS, Martins AB, Wunderlich ALM, Lopes GM, de Fatima Silva F, Komino ACM, Zaia DAM, Zaia CTBV, Lima FB, Uchoa ET. Glucocorticoids contribute to metabolic and liver impairments induced by lactation overnutrition in male adult rats. Front Physiol 2023; 14:1161582. [PMID: 37234421 PMCID: PMC10206267 DOI: 10.3389/fphys.2023.1161582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 04/20/2023] [Indexed: 05/28/2023] Open
Abstract
Introduction: Lactation overnutrition is a programming agent of energy metabolism, and litter size reduction leads to the early development of obesity, which persists until adulthood. Liver metabolism is disrupted by obesity, and increased levels of circulating glucocorticoids are pointed as a possible mediator for the obesity development, since bilateral adrenalectomy (ADX) can reduce obesity in different models of obesity. Methods: This study aimed to evaluate the effects of glucocorticoids on metabolic changes and liver lipogenesis and insulin pathway induced by lactation overnutrition. For this, on the postnatal day 3 (PND), 3 pups (small litter-SL) or 10 pups (normal litter-NL) were kept with each dam. On PND 60, male Wistar rats underwent bilateral adrenalectomy (ADX) or fictitious surgery (sham), and half of ADX animals received corticosterone (CORT- 25 mg/L) diluted in the drinking fluid. On PND 74, the animals were euthanized by decapitation for trunk blood collection, and liver dissection and storage. Results and Discussion: SL rats presented increased corticosterone, free fatty acids, total and LDL-cholesterol plasma levels, without changes in triglycerides (TG) and HDL-cholesterol. The SL group also showed increased content of liver TG, and expression of fatty acid synthase (FASN), but decreased expression of PI3Kp110 in the liver, compared to NL rats. In the SL group, the ADX decreased plasma levels of corticosterone, FFA, TG and HDL cholesterol, liver TG, and liver expression of FASN, and IRS2, compared to sham animals. In SL animals, CORT treatment increased plasma levels of TG and HDL cholesterol, liver TG, and expression of FASN, IRS1, and IRS2, compared with the ADX group. In summary, the ADX attenuated plasma and liver changes observed after lactation overnutrition, and CORT treatment could reverse most ADX-induced effects. Thus, increased circulating glucocorticoids are likely to play a pivotal role in liver and plasma impairments induced by lactation overnutrition in male rats.
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Affiliation(s)
- Camila F. de Souza
- Multicenter Postgraduate Program in Physiological Sciences, State University of Londrina, Londrina, Brazil
| | - Larissa Rugila S. Stopa
- Postgraduate Program in Physiological Sciences, State University of Londrina, Londrina, Brazil
| | - Andressa B. Martins
- Multicenter Postgraduate Program in Physiological Sciences, State University of Londrina, Londrina, Brazil
| | - Ana Luiza M. Wunderlich
- Postgraduate Program in Physiological Sciences, State University of Londrina, Londrina, Brazil
| | | | | | | | - Dimas A. M. Zaia
- Department of Chemistry, State University of Londrina, Londrina, Brazil
| | - Cassia Thaïs B. V. Zaia
- Multicenter Postgraduate Program in Physiological Sciences, State University of Londrina, Londrina, Brazil
- Postgraduate Program in Physiological Sciences, State University of Londrina, Londrina, Brazil
- Department of Physiological Sciences, State University of Londrina, Londrina, Brazil
| | - Fabio Bessa Lima
- Department of Physiology and Biophysics, University of Sao Paulo, Sao Paulo, Brazil
| | - Ernane Torres Uchoa
- Multicenter Postgraduate Program in Physiological Sciences, State University of Londrina, Londrina, Brazil
- Postgraduate Program in Physiological Sciences, State University of Londrina, Londrina, Brazil
- Department of Physiological Sciences, State University of Londrina, Londrina, Brazil
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Vanhoye X, Janin A, Caillaud A, Rimbert A, Venet F, Gossez M, Dijk W, Marmontel O, Nony S, Chatelain C, Durand C, Lindenbaum P, Rieusset J, Cariou B, Moulin P, Di Filippo M. APOB CRISPR-Cas9 Engineering in Hypobetalipoproteinemia: A Promising Tool for Functional Studies of Novel Variants. Int J Mol Sci 2022; 23:ijms23084281. [PMID: 35457099 PMCID: PMC9030618 DOI: 10.3390/ijms23084281] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 04/04/2022] [Accepted: 04/11/2022] [Indexed: 02/01/2023] Open
Abstract
Hypobetalipoproteinemia is characterized by LDL-cholesterol and apolipoprotein B (apoB) plasma levels below the fifth percentile for age and sex. Familial hypobetalipoproteinemia (FHBL) is mostly caused by premature termination codons in the APOB gene, a condition associated with fatty liver and steatohepatitis. Nevertheless, many families with a FHBL phenotype carry APOB missense variants of uncertain significance (VUS). We here aimed to develop a proof-of-principle experiment to assess the pathogenicity of VUS using the genome editing of human liver cells. We identified a novel heterozygous APOB-VUS (p.Leu351Arg), in a FHBL family. We generated APOB knock-out (KO) and APOB-p.Leu351Arg knock-in Huh7 cells using CRISPR-Cas9 technology and studied the APOB expression, synthesis and secretion by digital droplet PCR and ELISA quantification. The APOB expression was decreased by 70% in the heterozygous APOB-KO cells and almost abolished in the homozygous-KO cells, with a consistent decrease in apoB production and secretion. The APOB-p.Leu351Arg homozygous cells presented with a 40% decreased APOB expression and undetectable apoB levels in cellular extracts and supernatant. Thus, the p.Leu351Arg affected the apoB secretion, which led us to classify this new variant as likely pathogenic and to set up a hepatic follow-up in this family. Therefore, the functional assessment of APOB-missense variants, using gene-editing technologies, will lead to improvements in the molecular diagnosis of FHBL and the personalized follow-up of these patients.
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Affiliation(s)
- Xavier Vanhoye
- Service de Biochimie et de Biologie Moléculaire, Laboratoire de Biologie Médicale MultiSites, Hospices Civils de Lyon, F-69677 Bron, France; (X.V.); (A.J.); (O.M.); (S.N.); (C.C.)
| | - Alexandre Janin
- Service de Biochimie et de Biologie Moléculaire, Laboratoire de Biologie Médicale MultiSites, Hospices Civils de Lyon, F-69677 Bron, France; (X.V.); (A.J.); (O.M.); (S.N.); (C.C.)
- Institut NeuroMyoGène, CNRS UMR5310, INSERM U1217, Université Claude Bernard Lyon 1, Université de Lyon, F-69008 Lyon, France
| | - Amandine Caillaud
- Institut du Thorax, Nantes Université, CHU Nantes, CNRS, INSERM, F-44000 Nantes, France; (A.C.); (B.C.)
| | - Antoine Rimbert
- Institut du Thorax, Nantes Université, CNRS, INSERM, F-44000 Nantes, France; (A.R.); (W.D.); (P.L.)
| | - Fabienne Venet
- Laboratoire d’Immunologie, Edouard Herriot Hospital, Hospices Civils de Lyon, F-69437 Lyon, France; (F.V.); (M.G.)
- Centre International de Recherche en Infectiologie (CIRI), INSERM U1111, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Claude Bernard-Lyon 1, F-69364 Lyon, France
| | - Morgane Gossez
- Laboratoire d’Immunologie, Edouard Herriot Hospital, Hospices Civils de Lyon, F-69437 Lyon, France; (F.V.); (M.G.)
- Centre International de Recherche en Infectiologie (CIRI), INSERM U1111, CNRS, UMR5308, Ecole Normale Supérieure de Lyon, Université Claude Bernard-Lyon 1, F-69364 Lyon, France
| | - Wieneke Dijk
- Institut du Thorax, Nantes Université, CNRS, INSERM, F-44000 Nantes, France; (A.R.); (W.D.); (P.L.)
| | - Oriane Marmontel
- Service de Biochimie et de Biologie Moléculaire, Laboratoire de Biologie Médicale MultiSites, Hospices Civils de Lyon, F-69677 Bron, France; (X.V.); (A.J.); (O.M.); (S.N.); (C.C.)
- CarMen Laboratory, INSERM, INRA, INSA Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, F-69364 Lyon, France; (C.D.); (J.R.); (P.M.)
| | - Séverine Nony
- Service de Biochimie et de Biologie Moléculaire, Laboratoire de Biologie Médicale MultiSites, Hospices Civils de Lyon, F-69677 Bron, France; (X.V.); (A.J.); (O.M.); (S.N.); (C.C.)
| | - Charlotte Chatelain
- Service de Biochimie et de Biologie Moléculaire, Laboratoire de Biologie Médicale MultiSites, Hospices Civils de Lyon, F-69677 Bron, France; (X.V.); (A.J.); (O.M.); (S.N.); (C.C.)
| | - Christine Durand
- CarMen Laboratory, INSERM, INRA, INSA Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, F-69364 Lyon, France; (C.D.); (J.R.); (P.M.)
| | - Pierre Lindenbaum
- Institut du Thorax, Nantes Université, CNRS, INSERM, F-44000 Nantes, France; (A.R.); (W.D.); (P.L.)
| | - Jennifer Rieusset
- CarMen Laboratory, INSERM, INRA, INSA Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, F-69364 Lyon, France; (C.D.); (J.R.); (P.M.)
| | - Bertrand Cariou
- Institut du Thorax, Nantes Université, CHU Nantes, CNRS, INSERM, F-44000 Nantes, France; (A.C.); (B.C.)
| | - Philippe Moulin
- CarMen Laboratory, INSERM, INRA, INSA Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, F-69364 Lyon, France; (C.D.); (J.R.); (P.M.)
- Fédération d’Endocrinologie, Maladies Métaboliques, Diabète et Nutrition, Hôpital Louis Pradel, Hospices Civils de Lyon, F-69677 Bron, France
| | - Mathilde Di Filippo
- Service de Biochimie et de Biologie Moléculaire, Laboratoire de Biologie Médicale MultiSites, Hospices Civils de Lyon, F-69677 Bron, France; (X.V.); (A.J.); (O.M.); (S.N.); (C.C.)
- CarMen Laboratory, INSERM, INRA, INSA Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, F-69364 Lyon, France; (C.D.); (J.R.); (P.M.)
- Correspondence: ; Tel.: +33-04-7211-8994
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Conlon DM, Schneider CV, Ko YA, Rodrigues A, Guo K, Hand NJ, Rader DJ. Sortilin restricts secretion of apolipoprotein B-100 by hepatocytes under stressed but not basal conditions. J Clin Invest 2022; 132:144334. [PMID: 35113816 PMCID: PMC8920325 DOI: 10.1172/jci144334] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 02/02/2022] [Indexed: 12/02/2022] Open
Abstract
Genetic variants at the SORT1 locus in humans, which cause increased SORT1 expression in the liver, are significantly associated with reduced plasma levels of LDL cholesterol and apolipoprotein B (apoB). However, the role of hepatic sortilin remains controversial, as genetic deletion of sortilin in mice has resulted in variable and conflicting effects on apoB secretion. Here, we found that Sort1-KO mice on a chow diet and several Sort1-deficient hepatocyte lines displayed no difference in apoB secretion. When these models were challenged with high-fat diet or ER stress, the loss of Sort1 expression resulted in a significant increase in apoB-100 secretion. Sort1-overexpression studies yielded reciprocal results. Importantly, carriers of SORT1 variant with diabetes had larger decreases in plasma apoB, TG, and VLDL and LDL particle number as compared with people without diabetes with the same variants. We conclude that, under basal nonstressed conditions, loss of sortilin has little effect on hepatocyte apoB secretion, whereas, in the setting of lipid loading or ER stress, sortilin deficiency leads to increased apoB secretion. These results are consistent with the directionality of effect in human genetics studies and suggest that, under stress conditions, hepatic sortilin directs apoB toward lysosomal degradation rather than secretion, potentially serving as a quality control step in the apoB secretion pathway in hepatocytes.
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Affiliation(s)
- Donna M Conlon
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America
| | - Carolin V Schneider
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America
| | - Yi-An Ko
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America
| | - Amrith Rodrigues
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America
| | - Kathy Guo
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America
| | - Nicholas J Hand
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America
| | - Daniel J Rader
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States of America
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Kawakubo-Yasukochi T, Yano E, Kimura S, Nishinakagawa T, Mizokami A, Hayashi Y, Hatakeyama Y, Ohe K, Yasukochi A, Nakamura S, Jimi E, Hirata M. Hepatic glycogenolysis is determined by maternal high-calorie diet via methylation of Pygl and it is modified by oteocalcin administration in mice. Mol Metab 2021; 54:101360. [PMID: 34673295 PMCID: PMC8606545 DOI: 10.1016/j.molmet.2021.101360] [Citation(s) in RCA: 1] [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: 09/19/2021] [Revised: 10/11/2021] [Accepted: 10/17/2021] [Indexed: 12/24/2022] Open
Abstract
Objective Accumulating evidence indicates that an adverse perinatal environment contributes to a higher risk of metabolic disorders in the later life of the offspring. However, the underlying molecular mechanisms remain largely unknown. Thus, we investigated the contribution of maternal high-calorie diet and osteocalcin to metabolic homeostasis in the offspring. Methods Eight-week-old C57Bl/6N female mice were mated with age-matched males and allocated randomly to three groups: a normal-diet (ND) or a high-fat, high-sucrose diet group, which was administered either saline (control) or GluOC (10 ng/g body mass) from the day of mating to that of delivery, and the dams were fed a ND after the delivery. Pups weaned at 24 days after birth were analyzed. Results A maternal high-fat, high-sucrose diet during pregnancy causes metabolic disorders in the liver of the offspring via hypermethylation of the Pygl gene, encoding glycogen phosphorylase L, which mediates hepatic glycogenolysis. The reduced expression of Pygl induced by the maternal diet causes the hepatic accumulation of glycogen and triglyceride in the offspring, which remains in adulthood. In addition, the administration of uncarboxylated osteocalcin during pregnancy upregulates Pygl expression via both direct CREBH and ATF4 and indirect epigenomic pathways, mitigating the maternal diet-induced obesity and abnormal glucose and lipid metabolism in adulthood. Conclusions We propose that maternal energy status is reflected in the hepatic glycogenolysis capacity of the offspring via epigenetic modification of Pygl and uncarboxylated osteocalcin regulates glycogenolysis. A high-calorie diet during pregnancy causes metabolic disorders in mouse offspring. These are mediated by low liver expression of Pygl encoding glycogen phosphorylase. Hypermethylation of the Pygl promoter in utero suppresses subsequent gene expression. Modification and phenotypic changes are prevented by GluOC administration during pregnancy.
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Affiliation(s)
- Tomoyo Kawakubo-Yasukochi
- OBT Research Center, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
| | - Ena Yano
- OBT Research Center, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Soi Kimura
- OBT Research Center, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan; Section of Oral and Maxillofacial Oncology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Takuya Nishinakagawa
- Department of Immunological and Molecular Pharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan
| | - Akiko Mizokami
- OBT Research Center, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Yoshikazu Hayashi
- Division of Functional Structure, Department of Morphological Biology, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka 814-0193, Japan
| | - Yuji Hatakeyama
- Division of Functional Structure, Department of Morphological Biology, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka 814-0193, Japan
| | - Kenji Ohe
- Department of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan
| | - Atsushi Yasukochi
- Section of Oral and Maxillofacial Oncology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Seiji Nakamura
- Section of Oral and Maxillofacial Oncology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Eijiro Jimi
- OBT Research Center, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masato Hirata
- Oral Medicine Research Center, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka 814-0193, Japan.
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Chen P, Li Y, Xiao L. Berberine ameliorates nonalcoholic fatty liver disease by decreasing the liver lipid content via reversing the abnormal expression of MTTP and LDLR. Exp Ther Med 2021; 22:1109. [PMID: 34504563 PMCID: PMC8383777 DOI: 10.3892/etm.2021.10543] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 02/15/2021] [Indexed: 12/14/2022] Open
Abstract
The global incidence of nonalcoholic fatty liver disease (NAFLD) is increasing. The present study explored the effect and mechanism of berberine (BBR) on NAFLD in rats. Thirty-five Sprague-Dawley rats were randomly divided into the control and NAFLD groups, which were fed a normal diet or high-fat diet, respectively, for 8 weeks. Hematoxylin and eosin staining was performed on liver tissues and establishment of the NAFLD model was confirmed by microscopy. NAFLD rats were subsequently randomly subdivided and treated with saline or BBR for 8 weeks. The liver wet weight of rats in each group was measured, the liver tissue structure was observed by microscopy, and alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), triglyceride (TG), fasting blood glucose (FBG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) levels were detected using a semi-automatic biochemical detector. Reverse transcription-quantitative PCR and western blotting were performed to determine the mRNA and protein expression levels of microsomal triglyceride transfer protein (MTTP), apolipoprotein B and low-density lipoprotein receptor (LDLR). Compared with the control group, the liver wet weight of the NAFLD rats was higher; the liver showed obvious fatty degeneration and liver TG levels increased significantly, as did serum levels of ALT, AST, TC, TG, FBG, HDL and LDL, while expression of MTTP and LDLR significantly decreased. Compared with the saline-treated NAFLD rats, the BBR-treated rats had reduced liver wet weight, improved liver steatosis and a significant decrease in liver TG levels, while ALT, AST, TC, TG, and LDL serum levels significantly decreased and MTTP levels were significantly upregulated. In conclusion, BBR treatment ameliorated the fatty liver induced by a high-fat diet in rats. Furthermore, BBR reversed the abnormal expression of MTTP and LDLR in rats with high-fat diet induced-NAFLD. The present findings suggest that fatty liver could be improved by BBR administration, via reversing the abnormal expression of MTTP and LDLR and inhibiting lipid synthesis.
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Affiliation(s)
- Ping Chen
- Department of Pharmacy, Affiliated Hospital of Shandong Medical College, Linyi, Shandong 276000, P.R. China
| | - Yusheng Li
- Department of Pharmacy, Linyi Maternal and Child Health Care Hospital, Linyi, Shandong 276000, P.R. China
| | - Li Xiao
- Department of Pharmacy, Linyi Maternal and Child Health Care Hospital, Linyi, Shandong 276000, P.R. China
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Silva JL, Leocádio PCL, Reis JM, Campos GP, Capettini LSA, Foureaux G, Ferreira AJ, Windmöller CC, Santos FA, Oriá RB, Crespo-López ME, Alvarez-Leite JI. Oral methylmercury intoxication aggravates cardiovascular risk factors and accelerates atherosclerosis lesion development in ApoE knockout and C57BL/6 mice. Toxicol Res 2020; 37:311-321. [PMID: 34295795 DOI: 10.1007/s43188-020-00066-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 09/09/2020] [Accepted: 09/23/2020] [Indexed: 01/08/2023] Open
Abstract
Methylmercury (MeHg) intoxication is associated with hypertension, hypercholesterolemia, and atherosclerosis by mechanisms that are not yet fully understood. We investigated the effects of MeHg intoxication in atherosclerosis-prone (ApoE-KO) and resistant C57BL/6 mice. Mice were submitted to carotid stenosis surgery (to induce atherosclerosis faster) and received water or MeHg solution (20 mg/L) for 15 days. Tail plethysmography was performed before and after MeHg exposure. Food and MeHg solution intakes were monitored weekly. On the 15th day, mice were submitted to intravital fluorescence microscopy of mesenteric vasculature to observe in vivo leukocyte rolling and adhesion. Results showed that despite the high hair and liver Hg concentrations in the MeHg group, food and water (or MeHg solution) consumption and liver function marker levels were similar to those in controls. MeHg exposure increased total cholesterol, the atherogenic (non-HDL) fraction and systolic and diastolic blood pressure. MeHg exposure also induced inflammation, as seen by the increased rolling and adhered leukocytes in the mesenteric vasculature. Atherosclerosis lesions were more extensive in the aorta and carotid sites of MeHg-ApoE knockout mice. Surprisingly, MeHg exposure also induced atherosclerosis lesions in C57BL/6 mice, which are resistant to atherosclerosis formation. We concluded that MeHg intoxication might represent a risk for cardiovascular diseases since it accelerates atherogenesis by exacerbating several independent risk factors.
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Affiliation(s)
- Janayne L Silva
- Departamento de Bioquímica e Imunologia ICB/UFMG Caixa Postal 486, Belo Horizonte, MG CEP 30161-970 Brazil
| | - Paola C L Leocádio
- Departamento de Nutrição e Saúde, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais Brazil
| | - Jonas M Reis
- Departamento de Bioquímica e Imunologia ICB/UFMG Caixa Postal 486, Belo Horizonte, MG CEP 30161-970 Brazil
| | - Gianne P Campos
- Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais Brazil
| | - Luciano S A Capettini
- Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais Brazil
| | - Giselle Foureaux
- Departamento de Morfologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais Brazil
| | - Anderson J Ferreira
- Departamento de Morfologia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais Brazil
| | - Cláudia C Windmöller
- Departamento de Química, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais Brazil
| | - Flávia A Santos
- Departamento de Morfologia, Universidade Federal Do Ceará, Fortaleza, Ceará Brazil
| | - Reinaldo B Oriá
- Departamento de Morfologia, Universidade Federal Do Ceará, Fortaleza, Ceará Brazil
| | - Maria E Crespo-López
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará Brazil
| | - Jacqueline I Alvarez-Leite
- Departamento de Bioquímica e Imunologia ICB/UFMG Caixa Postal 486, Belo Horizonte, MG CEP 30161-970 Brazil
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9
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Zhang Y, He H, Zeng YP, Yang LD, Jia D, An ZM, Jia WG. Lipoprotein A, combined with alanine aminotransferase and aspartate aminotransferase, contributes to predicting the occurrence of NASH: a cross-sectional study. Lipids Health Dis 2020; 19:134. [PMID: 32527258 PMCID: PMC7288690 DOI: 10.1186/s12944-020-01310-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 06/04/2020] [Indexed: 02/08/2023] Open
Abstract
Background Nonalcoholic steatohepatitis (NASH) progresses from simple nonalcoholic fatty liver (NAFL) and has a poor prognosis. Abnormal lipid metabolism is closely related to the occurrence and development of nonalcoholic fatty liver disease (NAFLD). This study aimed to study the relationships between serum lipid metabolites and NASH, and to improve the early diagnosis of NASH. Methods This study included 86 NAFLD patients (23 NASH and 63 NAFL), and 81 unaffected individuals as controls from West China Hospital between October 2018 and May 2019. With lipid metabolites as the focus of the study, the differences in lipid metabolites were compared between the control group, NAFL patients, and NASH patients. Logistic regression analysis was used to examine the risk factors of NASH. Finally, receiver operating characteristic curve (ROC curve) was used to analyze the efficacy of the metabolites in NASH prediction. Results The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lipoprotein A (LPA) increased with the severity of NAFLD. In NAFLD patients, LPA (OR:1.61; 95%CI: 1.03–2.52) was a potential risk factor for NASH, and ROC analysis showed that the combination of LPA, ALT, and AST had a greater predictive efficiency for NASH. Conclusions Abnormal apolipoprotein/lipoprotein is closely related to lipid metabolism disorder in patients with NAFLD. In NAFL, the combination of LPA, ALT, and AST contributes to predicting the occurrence of NASH. LPA may be a potential biomarker and therapeutic target for diagnosing and treating NASH.
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Affiliation(s)
- Yu Zhang
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, People's Republic of China
| | - He He
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Yu-Ping Zeng
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Li-Dan Yang
- Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Dan Jia
- Outpatient department, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China
| | - Zhen-Mei An
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, People's Republic of China.
| | - Wei-Guo Jia
- Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, 610031, Sichuan, China
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10
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Shen Y, Xiao X, Wu K, Wang Y, Yuan Y, Liu J, Sun S, Liu J. Effects and molecular mechanisms of Ninghong black tea extract in nonalcoholic fatty liver disease of rats. J Food Sci 2020; 85:800-807. [PMID: 32090345 DOI: 10.1111/1750-3841.14846] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 09/03/2019] [Accepted: 09/16/2019] [Indexed: 12/24/2022]
Abstract
The aim of this study is to observe the effects of Ninghong black tea extract on fat deposition and high-fat diet-induced nonalcoholic fatty liver disease (NAFLD) and to explore the potential mechanisms of these effect. Under 2% Ninghong black tea extract diet feeding in rat model, the results showed that Ninghong black tea extract decreased the body fat ratio and the number of lipid droplets in the liver and significantly alleviated NAFLD in the rat model. The real-time fluorescence quantitative polymerase chain reaction results showed that Ninghong black tea extract significantly upregulated the expression of peroxisome proliferator-activated receptor α (PPARα), which is important in fatty acid β-oxidation, and microsomal triglyceride transfer protein (MTP), which plays an important role in the synthesis of very low density lipoprotein (VLDL). By promoting the expression of PPARα and MTP in liver tissue and thereby promoting fatty acid β-oxidation and VLDL synthesis, Ninghong black tea extract relieves high-fat diet-induced NAFLD.
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Affiliation(s)
- Yu Shen
- Molecular Biology Research Center, School of Life Sciences, Central South Univ., Changsha, 410078, China
| | - Xiaojuan Xiao
- Molecular Biology Research Center, School of Life Sciences, Central South Univ., Changsha, 410078, China
| | - Kunlu Wu
- Molecular Biology Research Center, School of Life Sciences, Central South Univ., Changsha, 410078, China
| | - Yanpeng Wang
- Molecular Biology Research Center, School of Life Sciences, Central South Univ., Changsha, 410078, China
| | - Yijun Yuan
- Molecular Biology Research Center, School of Life Sciences, Central South Univ., Changsha, 410078, China
| | - Jianwei Liu
- Molecular Biology Research Center, School of Life Sciences, Central South Univ., Changsha, 410078, China
| | - Shuming Sun
- Molecular Biology Research Center, School of Life Sciences, Central South Univ., Changsha, 410078, China
| | - Jing Liu
- Molecular Biology Research Center, School of Life Sciences, Central South Univ., Changsha, 410078, China
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11
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Zhang J, Jazii FR, Haghighi MM, Alvares D, Liu L, Khosraviani N, Adeli K. miR-130b is a potent stimulator of hepatic very-low-density lipoprotein assembly and secretion via marked induction of microsomal triglyceride transfer protein. Am J Physiol Endocrinol Metab 2020; 318:E262-E275. [PMID: 31821038 DOI: 10.1152/ajpendo.00276.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
miR-130b is a microRNA whose expression is particularly elevated within adipose tissue and in the circulation in diabetic states. Hepatic miR-130b expression has been linked to hepatocellular carcinoma and changes in lipid metabolism. Here, we investigated the role of miR-130b in hepatic lipid homeostasis and lipoprotein export. We observed that overexpression of miR-130b-3p or -5p in HepG2 cells markedly enhanced the secretion of very-low-density lipoprotein (VLDL) particles, enhanced the secretion of [3H]glycerol metabolically labeled triglyceride (TG), and significantly increased the number or the average size of lipid droplets (LDs), respectively. Overexpression of miR-130b also altered the expression of key genes involved in lipid metabolism and in particular markedly increased both mRNA and protein expression levels of microsomal triglyceride transfer protein (MTP). Conversely, the miR-130b inhibitor decreased mRNA levels of MTP and fatty acid synthase (FAS) in HepG2 cells. However, dual-luciferase reporter assays indicated that MTP is not a direct target of miR-130b-3p. miR-130b overexpression did not alter de novo synthesized TG or the stability and secretion of apolipoprotein B 100. Interestingly, knockdown of phosphatase and tensin homolog (PTEN) blocked the upregulation of MTP mRNA induced by miR-130b. Finally, miR-130b-induced stimulation of VLDL secretion was also observed in a second hepatocyte cell culture model, immortalized human hepatocytes, confirming the effects observed in HepG2 cells. Overall, these data suggest a potential role for miR-130b in promoting hepatic VLDL assembly and secretion mediated by marked stimulation of MTP expression and TG mobilization. Thus miR-130b overexpression corrects the defect in VLDL production in HepG2 cells.
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Affiliation(s)
- Jing Zhang
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Ferdous Rastgar Jazii
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Mahdi Montazer Haghighi
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Danielle Alvares
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Lipei Liu
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Negar Khosraviani
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Khosrow Adeli
- Molecular Medicine, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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12
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Song MJ, Malhi H. The unfolded protein response and hepatic lipid metabolism in non alcoholic fatty liver disease. Pharmacol Ther 2019; 203:107401. [PMID: 31419516 PMCID: PMC6848795 DOI: 10.1016/j.pharmthera.2019.107401] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 08/08/2019] [Indexed: 12/19/2022]
Abstract
Nonalcoholic fatty liver disease is a major public health burden. Although many features of nonalcoholic fatty liver disease pathogenesis are known, the specific mechanisms and susceptibilities that determine an individual's risk of developing nonalcoholic steatohepatitis versus isolated steatosis are not well delineated. The predominant and defining histologic and imaging characteristic of nonalcoholic fatty liver disease is the accumulation of lipids. Dysregulation of lipid homeostasis in hepatocytes leads to transient generation or accumulation of toxic lipids that result in endoplasmic reticulum (ER) stress with inflammation, hepatocellular damage, and apoptosis. ER stress activates the unfolded protein response (UPR) which is classically viewed as an adaptive pathway to maintain protein folding homeostasis. Recent studies have uncovered the contribution of the UPR sensors in the regulation of hepatic steatosis and in the cellular response to lipotoxic stress. Interestingly, the UPR sensors can be directly activated by toxic lipids, independently of the accumulation of misfolded proteins, termed lipotoxic and proteotoxic stress, respectively. The dual function of the UPR sensors in protein and lipid homeostasis suggests that these two types of stress are interconnected likely due to the central role of the ER in protein folding and trafficking and lipid biosynthesis and trafficking, such that perturbations in either impact the function of the ER and activate the UPR sensors in an effort to restore homeostasis. The precise molecular similarities and differences between proteotoxic and lipotoxic ER stress are beginning to be understood. Herein, we provide an overview of the mechanisms involved in the activation and cross-talk between the UPR sensors, hepatic lipid metabolism, and lipotoxic stress, and discuss the possible therapeutic potential of targeting the UPR in nonalcoholic fatty liver disease.
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Affiliation(s)
- Myeong Jun Song
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, United States of America; Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Harmeet Malhi
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, United States of America.
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13
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Liang X, Xie G, Wu X, Su M, Yang B. Effect of prenatal PFOS exposure on liver cell function in neonatal mice. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:18240-18246. [PMID: 31041707 DOI: 10.1007/s11356-019-05245-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Revised: 03/13/2019] [Accepted: 04/22/2019] [Indexed: 05/28/2023]
Abstract
Perfluorooctane sulfonate (PFOS), a hepatotoxic pollutant, is detected in the human cord blood, and it may induce health risk to an embryo. In this study, we established intrauterine exposure to PFOS in mice to evaluate potential impacts of PFOS on postnatal day 1 (PND1) offspring through conducting biochemical tests, quantitative PCR, and immunostaining. As results, PFOS-exposed maternal mice showed marked hepatomegaly and induced liver steatosis in a high dose of 5 mg PFOS/kg. In PND1 mice, intrahepatic contents of triglyceride, total cholesterol, and LDL were elevated by high-dose PFOS exposure, while intracellular HDL content was decreased. As shown in quantitative PCR, functional messenger RNAs of cytochrome P4A14 (CYP4A14) for fatty acid oxidation, CD36 for hepatic fatty acid uptake, and apolipoprotein B100 (APOB) and fibroblast growth factor 21 (FGF21) for hepatic export of lipids in PND1 livers were changed when compared to those in PFOS-free controls. In further validations, immunofluorescence stains showed that hepatic CYP4A14 and CD36 immunoreactive cells were increased in PFOS-exposed PND1 mice. In addition, reduced immunofluorescence-positive cells of APOB and FGF21 were observed in PND1 livers. Collectively, these preliminary findings demonstrate that prenatal exposure to PFOS may affect lipid metabolism in liver cells of PND1 mice.
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Affiliation(s)
- Xiaoliu Liang
- College of Pharmacy, Guangxi Medical University, 22 Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Guojie Xie
- Department of Gynecology, Guigang City People's Hospital, The Eighth Affiliated Hospital of Guangxi Medical University, Guigang, 537100, Guangxi, People's Republic of China
| | - Xinmou Wu
- College of Pharmacy, Guangxi Medical University, 22 Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Min Su
- Key Laboratory of Tumor Immunology and Microenvironmental Regulation, Guilin Medical University, Huan Cheng North 2nd Road 109, Guilin, 541004, People's Republic of China.
| | - Bin Yang
- College of Pharmacy, Guangxi Medical University, 22 Shuangyong Road, Nanning, 530021, Guangxi, China.
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14
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Xiao J, Deng YM, Liu XR, Cao JP, Zhou M, Tang YL, Xiong WH, Jiang ZS, Tang ZH, Liu LS. PCSK9: A new participant in lipophagy in regulating atherosclerosis? Clin Chim Acta 2019; 495:358-364. [PMID: 31075236 DOI: 10.1016/j.cca.2019.05.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 05/03/2019] [Accepted: 05/06/2019] [Indexed: 12/12/2022]
Abstract
Proprotein convertase subtilisin kexin 9 (PCSK9) regulates lipid metabolism by degrading low-density lipoprotein receptor on the surface of hepatocytes. PCSK9-mediated lipid degradation is associated with lipophagy. Lipophagy is a process by which autophagosomes selectively sequester lipid-droplet-stored lipids and are delivered to lysosomes for degradation. Lipophagy was first discovered in hepatocytes, and its occurrence provides important fundamental insights into how lipid metabolism regulates cellular physiology and pathophysiology. Furthermore, PCSK9 may regulate lipid levels by affecting lipophagy. This review will discuss recent advances by which PCSK9 mediates lipid degradation via the lipophagy pathway and present lipophagy as a potential therapeutic target for atherosclerosis.
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Affiliation(s)
- Jun Xiao
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, University of South China, Hengyang, Hunan 421001, PR China
| | - Yi-Min Deng
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, University of South China, Hengyang, Hunan 421001, PR China
| | - Xiang-Rui Liu
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, University of South China, Hengyang, Hunan 421001, PR China
| | - Jian-Ping Cao
- Hunan Environmental Biology Vocational and Technical College, Hengyang, Hunan 421001, PR China
| | - Min Zhou
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, University of South China, Hengyang, Hunan 421001, PR China
| | - Ya-Ling Tang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, University of South China, Hengyang, Hunan 421001, PR China
| | - Wen-Hao Xiong
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, University of South China, Hengyang, Hunan 421001, PR China
| | - Zhi-Sheng Jiang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, University of South China, Hengyang, Hunan 421001, PR China
| | - Zhi-Han Tang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, University of South China, Hengyang, Hunan 421001, PR China.
| | - Lu-Shan Liu
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, University of South China, Hengyang, Hunan 421001, PR China.
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15
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Wang T, Turko IV. Proteomic Toolbox To Standardize the Separation of Extracellular Vesicles and Lipoprotein Particles. J Proteome Res 2018; 17:3104-3113. [PMID: 30080417 DOI: 10.1021/acs.jproteome.8b00225] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Circulating in blood, extracellular vesicles (EVs) and lipoprotein particles (LPs) have diagnostic and prognostic value. To unambiguously define their functions, separation protocols need to be developed. However, because of their similar size and density, traditional approaches to separate EVs and LPs often fail to provide the required resolution. Further development and standardization of affinity-based protocols is necessary, and a quantitative method is needed to assess the efficiency of LP depletion from EV samples. In the present study, we propose the simultaneous quantification of three groups of proteins by mass spectrometry as a toolbox to evaluate prospective separation protocols. We generated 15N-labeled internal standards for quantification of (i) EV-specific proteins, (ii) all classes and subclasses of apolipoproteins constituting LPs, and (iii) several major serum proteins. These standards were then used in multiple reaction monitoring assay to evaluate the performance of size-exclusion chromatography, heparin-Sepharose, lipopolysaccharide-Sepharose, (2-hydroxypropyl)-β-cyclodextrin-Sepharose, and concanavalin A-Sepharose in separating serum EVs and LPs. The efficiency of a resin to separate EVs from non-EV substances could be jeopardized by simultaneous EV aggregation. Therefore, dynamic light scattering analysis was used in this study in addition to the proteomic toolbox when making a recommendation to use particular resin for EV isolation. On the basis of our measurements, we concluded that none of the individual separation protocols used in this study resulted in LP-free EVs, and the combination of two protocols may be complex due to low EV yield. Overall, this further points to the importance of proposed proteomic toolbox for the future evaluation of EV separation protocols.
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Affiliation(s)
- Tingting Wang
- Biomolecular Measurement Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States.,Institute for Bioscience and Biotechnology Research , Rockville , Maryland 20850 , United States
| | - Illarion V Turko
- Biomolecular Measurement Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States.,Institute for Bioscience and Biotechnology Research , Rockville , Maryland 20850 , United States
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16
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Sirwi A, Hussain MM. Lipid transfer proteins in the assembly of apoB-containing lipoproteins. J Lipid Res 2018; 59:1094-1102. [PMID: 29650752 DOI: 10.1194/jlr.r083451] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 04/12/2018] [Indexed: 11/20/2022] Open
Abstract
A better understanding of intracellular lipoprotein assembly may help identify proteins with important roles in lipid disorders. apoB-containing lipoproteins (B-lps) are macromolecular lipid and protein micelles that act as specialized transport vehicles for hydrophobic lipids. They are assembled predominantly in enterocytes and hepatocytes to transport dietary and endogenous fat, respectively, to different tissues. Assembly occurs in the endoplasmic reticulum (ER) and is dependent on lipid resynthesis in the ER and on a chaperone, namely, microsomal triglyceride transfer protein (MTTP). Precursors for lipid synthesis are obtained from extracellular sources and from cytoplasmic lipid droplets. MTTP is the major and essential lipid transfer protein that transfers phospholipids and triacylglycerols to nascent apoB for the assembly of lipoproteins. Assembly is aided by cell death-inducing DFF45-like effector B and by phospholipid transfer protein, which may facilitate additional deposition of triacylglycerols and phospholipids, respectively, to apoB. Here, we summarize the current understanding of the different steps in the assembly of B-lps and discuss the role of lipid transfer proteins in these steps to help identify new clinical targets for lipid-associated disorders, such as heart disease.
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Affiliation(s)
- Alaa Sirwi
- School of Graduate Studies, Molecular and Cell Biology Program, State University of New York Downstate Medical Center, Brooklyn, NY
| | - M Mahmood Hussain
- New York University Winthrop Hospital, Mineola, NY and Veterans Affairs New York Harbor Healthcare System, Brooklyn, NY
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17
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Howell GE, McDevitt E, Henein L, Mulligan C, Young D. "Trans-nonachlor increases extracellular free fatty acid accumulation and de novo lipogenesis to produce hepatic steatosis in McArdle-RH7777 cells". Toxicol In Vitro 2018; 50:285-292. [PMID: 29654899 DOI: 10.1016/j.tiv.2018.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 03/28/2018] [Accepted: 04/05/2018] [Indexed: 12/19/2022]
Abstract
Recent studies suggest there may be an environmental exposure component to the development and progression of non-alcoholic fatty liver disease (NAFLD) involving the organochlorine (OC) pesticides or their metabolites. However, the roles of OC compounds in the development of NAFLD has not been fully elucidated. Therefore, the current study was designed to determine if exposure to trans-nonachlor, a prevalent OC compound, could promote hepatocyte lipid accumulation and determine potential pro-steatotic mechanisms. McArdle-RH7777 (McA) hepatoma cells were incubated with trans-nonachlor for 24 h then neutral lipid accumulation was determined by Oil Red O staining. Exposure to trans-nonachlor produced a concentration dependent increase in neutral lipid accumulation. Trans-nonachlor also increased extracellular free fatty acid-induced neutral lipid accumulation which appears to be due at least in part to increased free fatty acid accumulation as evident by increased accumulation of Bodipy labeled dodecanoic acid. Additionally, 14C-acetate incorporation into total cellular lipids was increased by trans-nonachlor implicating increased de novo lipogenesis (DNL) as a potential mediator of trans-nonachlor-induced neutral lipid accumulation. Taken together, the present data indicate exposure to trans-nonachlor has a direct, pro-steatotic effect on hepatocytes to increase lipid accumulation through the combinatorial actions of extracellular free fatty acid accumulation and increased DNL.
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Affiliation(s)
- George Eli Howell
- Mississippi State University College of Veterinary Medicine, Department of Basic Sciences, Mississippi State, MS 39762, United States.
| | - Erin McDevitt
- Mississippi State University College of Veterinary Medicine, Department of Basic Sciences, Mississippi State, MS 39762, United States
| | - Lucie Henein
- Mississippi State University College of Veterinary Medicine, Department of Basic Sciences, Mississippi State, MS 39762, United States
| | - Charlee Mulligan
- Mississippi State University College of Veterinary Medicine, Department of Basic Sciences, Mississippi State, MS 39762, United States
| | - Darian Young
- Mississippi State University College of Veterinary Medicine, Department of Basic Sciences, Mississippi State, MS 39762, United States
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18
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Khound R, Taher J, Baker C, Adeli K, Su Q. GLP-1 Elicits an Intrinsic Gut-Liver Metabolic Signal to Ameliorate Diet-Induced VLDL Overproduction and Insulin Resistance. Arterioscler Thromb Vasc Biol 2017; 37:2252-2259. [PMID: 29074588 DOI: 10.1161/atvbaha.117.310251] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 10/13/2017] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Perturbations in hepatic lipid and very-low-density lipoprotein (VLDL) metabolism are involved in the pathogenesis of obesity and hepatic insulin resistance. The objective of this study is to delineate the mechanism of subdiaphragmatic vagotomy in preventing obesity, hyperlipidemia, and insulin resistance. APPROACH AND RESULTS By subjecting the complete subdiaphragmatic vagotomized mice to various nutritional conditions and investigating hepatic de novo lipogenesis pathway, we found that complete disruption of subdiaphragmatic vagal signaling resulted in a significant decrease of circulating VLDL-triglyceride compared with the mice obtained sham procedure. Vagotomy further prevented overproduction of VLDL-triglyceride induced by an acute fat load and a high-fat diet-induced obesity, hyperlipidemia, hepatic steatosis, and glucose intolerance. Mechanistic studies revealed that plasma glucagon-like peptide-1 was significantly raised in the vagotomized mice, which was associated with significant reductions in mRNA and protein expression of SREBP-1c (sterol regulatory element-binding protein 1c), SCD-1 (stearoyl-CoA desaturase-1), and FASN (fatty acid synthase), as well as enhanced hepatic insulin sensitivity. In vitro, treating mouse primary hepatocytes with a glucagon-like peptide-1 receptor agonist, exendin-4, for 48 hours inhibited free fatty acid, palmitic acid treatment induced de novo lipid synthesis, and VLDL secretion from hepatocytes. CONCLUSIONS Elevation of glucagon-like peptide-1 in vagotomized mice may prevent VLDL overproduction and insulin resistance induced by high-fat diet. These novel findings, for the first time, delineate an intrinsic gut-liver regulatory circuit that is mediated by glucagon-like peptide-1 in regulating hepatic energy metabolism.
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Affiliation(s)
- Rituraj Khound
- From the Department of Nutrition and Health Sciences, University of Nebraska-Lincoln (R.K., Q.S.); Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada (J.T., C.B., K.A.); and Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Ontario, Canada (J.T.)
| | - Jennifer Taher
- From the Department of Nutrition and Health Sciences, University of Nebraska-Lincoln (R.K., Q.S.); Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada (J.T., C.B., K.A.); and Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Ontario, Canada (J.T.)
| | - Christopher Baker
- From the Department of Nutrition and Health Sciences, University of Nebraska-Lincoln (R.K., Q.S.); Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada (J.T., C.B., K.A.); and Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Ontario, Canada (J.T.)
| | - Khosrow Adeli
- From the Department of Nutrition and Health Sciences, University of Nebraska-Lincoln (R.K., Q.S.); Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada (J.T., C.B., K.A.); and Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Ontario, Canada (J.T.)
| | - Qiaozhu Su
- From the Department of Nutrition and Health Sciences, University of Nebraska-Lincoln (R.K., Q.S.); Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada (J.T., C.B., K.A.); and Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Ontario, Canada (J.T.).
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19
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Lepreux S, Villeneuve J, Dewitte A, Bérard AM, Desmoulière A, Ripoche J. CD40 signaling and hepatic steatosis: Unanticipated links. Clin Res Hepatol Gastroenterol 2017; 41:357-369. [PMID: 27989689 DOI: 10.1016/j.clinre.2016.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 10/10/2016] [Accepted: 11/07/2016] [Indexed: 02/08/2023]
Abstract
Obesity predisposes to an increased risk of nonalcoholic fatty liver disease (NAFLD). Hepatic steatosis is the key pathological feature of NAFLD and has emerged as a metabolic disorder in which innate and adaptive arms of the immune response play a central role in disease pathogenesis. Recent studies have revealed unexpected relationships between CD40 signaling and hepatic steatosis in high fat diet rodent models. CD154, the ligand of CD40, is a mediator of inflammation and controls several critical events of innate and adaptive immune responses. In the light of these reports, we discuss potential links between CD40 signaling and hepatic steatosis in NAFLD.
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Affiliation(s)
| | - Julien Villeneuve
- Cell and Developmental Biology Programme, Centre for Genomic Regulation, 08003 Barcelona, Spain
| | - Antoine Dewitte
- Service d'Anesthésie-Réanimation II, CHU de Bordeaux, 33600 Pessac, France
| | - Annie M Bérard
- Service de Biochimie, CHU de Bordeaux, 33000 Bordeaux, France
| | | | - Jean Ripoche
- INSERM U1026, Université de Bordeaux, 33000 Bordeaux, France.
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20
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Wang J, Zhu W, Huang S, Xu L, Miao M, Wu C, Yu C, Li Y, Xu C. Serum apoB levels independently predict the development of non-alcoholic fatty liver disease: A 7-year prospective study. Liver Int 2017; 37:1202-1208. [PMID: 28106941 DOI: 10.1111/liv.13363] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 01/08/2017] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS Cross-sectional studies have shown that apolipoprotein B (apoB) is positively associated with the prevalence of non-alcoholic fatty liver disease (NAFLD). This study aimed to investigate the prospective relationship between the serum apoB levels and the development of NAFLD in a Chinese population. METHODS A cohort of 7077 initially NAFLD-free participants was enrolled in this prospectively study. The incidence of NAFLD was calculated among participants with different baseline serum apoB quintiles. Cox proportional hazards regression analyses were conducted to calculate the risks for incident NAFLD. RESULTS During 41 555 person-year follow-ups, 1139 incident NAFLD cases were identified. The baseline apoB levels were linear and positively correlated with NAFLD incidence. The incidence was 16.99, 22.63, 24.73, 37.51 and 42.77 per 1000 person-year follow-up for participants with baseline apoB levels in quintiles 1-5, respectively. Compared with participants with baseline apoB levels in quintile 1, the hazard ratios (95% confidence interval) for incident NAFLD were 1.353 (1.100-1.663), 1.482 (1.207-1.820), 2.232 (1.832-2.720) and 2.543 (2.082-3.106) for participants with baseline apoB levels in quintile 2-5, respectively. The hazard ratios were attenuated but remained statistically significant after adjusting for age, gender, body mass index and variables associated with metabolic syndrome. CONCLUSION Elevated serum apoB levels independently predict an increased risk for incident NAFLD.
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Affiliation(s)
- Jinghua Wang
- Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, China
| | - Wanlin Zhu
- Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Department of Gastroenterology, Lishui Central Hospital, Lishui, China
| | - Shujun Huang
- Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Lei Xu
- Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Department of Gastroenterology, Ningbo First Hospital, Ningbo, China
| | - Min Miao
- Department of Internal Medicine, Zhenhai Lianhua Hospital, Ningbo, China
| | - Chenjiao Wu
- Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Chaohui Yu
- Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, China
| | - Youming Li
- Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, China
| | - Chengfu Xu
- Department of Gastroenterology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China.,Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, China
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21
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Liu M, Chung S, Shelness GS, Parks JS. Hepatic ABCA1 deficiency is associated with delayed apolipoprotein B secretory trafficking and augmented VLDL triglyceride secretion. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1035-1043. [PMID: 28694219 DOI: 10.1016/j.bbalip.2017.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 06/30/2017] [Accepted: 07/05/2017] [Indexed: 11/30/2022]
Abstract
ATP binding cassette transporter A1 (ABCA1) is a membrane transporter that facilitates nascent HDL formation. Tangier disease subjects with complete ABCA1 deficiency have <5% of normal levels of plasma HDL, elevated triglycerides (TGs), and defective vesicular trafficking in fibroblasts and macrophages. Hepatocyte-specific ABCA1 knockout mice (HSKO) have a similar lipid phenotype with 20% of normal plasma HDL levels and a two-fold elevation of plasma TGs due to hepatic overproduction of large, triglyceride-enriched VLDL. We hypothesized that enhanced VLDL TG secretion in the absence of hepatocyte ABCA1 is due to altered intracellular trafficking of apolipoprotein B (apoB), resulting in augmented TG addition to nascent VLDL. We found that trafficking of newly synthesized apoB through the secretory pathway was delayed in ABCA1-silenced rat hepatoma cells and HSKO primary hepatocytes, relative to controls. Endoglycosidase H treatment of cellular apoB revealed a likely delay in apoB trafficking in post-ER compartments. The reduced rate of protein trafficking was also observed for an adenoviral-expressed GPI-linked fluorescent fusion protein, but not albumin, suggesting a selective delay of secretory cargoes in the absence of hepatocyte ABCA1. Our results suggest an important role for hepatic ABCA1 in regulating secretory trafficking and modulating VLDL expansion during the TG accretion phase of hepatic lipoprotein particle assembly.
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Affiliation(s)
- Mingxia Liu
- Department of Internal Medicine-Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA.
| | - Soonkyu Chung
- Department of Internal Medicine-Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Gregory S Shelness
- Department of Internal Medicine-Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - John S Parks
- Department of Internal Medicine-Section on Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA; Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, USA
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22
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Falcón V, Acosta-Rivero N, González S, Dueñas-Carrera S, Martinez-Donato G, Menéndez I, Garateix R, Silva JA, Acosta E, Kourı J. Ultrastructural and biochemical basis for hepatitis C virus morphogenesis. Virus Genes 2017; 53:151-164. [PMID: 28233195 DOI: 10.1007/s11262-017-1426-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 01/06/2017] [Indexed: 12/16/2022]
Abstract
Chronic infection with HCV is a leading cause of cirrhosis, hepatocellular carcinoma and liver failure. One of the least understood steps in the HCV life cycle is the morphogenesis of new viral particles. HCV infection alters the lipid metabolism and generates a variety of microenvironments in the cell cytoplasm that protect viral proteins and RNA promoting viral replication and assembly. Lipid droplets (LDs) have been proposed to link viral RNA synthesis and virion assembly by physically associating these viral processes. HCV assembly, envelopment, and maturation have been shown to take place at specialized detergent-resistant membranes in the ER, rich in cholesterol and sphingolipids, supporting the synthesis of luminal LDs-containing ApoE. HCV assembly involves a regulated allocation of viral and host factors to viral assembly sites. Then, virus budding takes place through encapsidation of the HCV genome and viral envelopment in the ER. Interaction of ApoE with envelope proteins supports the viral particle acquisition of lipids and maturation. HCV secretion has been suggested to entail the ion channel activity of viral p7, several components of the classical trafficking and autophagy pathways, ESCRT, and exosome-mediated export of viral RNA. Here, we review the most recent advances in virus morphogenesis and the interplay between viral and host factors required for the formation of HCV virions.
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Affiliation(s)
- Viviana Falcón
- Centro de Ingeniería Genética y Biotecnología, P.O. Box 6162, C.P. 10600, Havana, Cuba.
| | - Nelson Acosta-Rivero
- National Center for Scientific Research, P.O. Box 6414, 10600, Havana, Cuba. .,Centre for Protein Studies, Faculty of Biology, University of Havana, 10400, Havana, Cuba.
| | | | | | | | - Ivon Menéndez
- Centro de Ingeniería Genética y Biotecnología, P.O. Box 6162, C.P. 10600, Havana, Cuba
| | - Rocio Garateix
- Centro de Ingeniería Genética y Biotecnología, P.O. Box 6162, C.P. 10600, Havana, Cuba
| | - José A Silva
- Centro de Ingeniería Genética y Biotecnología, P.O. Box 6162, C.P. 10600, Havana, Cuba
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23
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Zhang J, Zamani M, Thiele C, Taher J, Amir Alipour M, Yao Z, Adeli K. AUP1 (Ancient Ubiquitous Protein 1) Is a Key Determinant of Hepatic Very-Low-Density Lipoprotein Assembly and Secretion. Arterioscler Thromb Vasc Biol 2017; 37:633-642. [PMID: 28183703 DOI: 10.1161/atvbaha.117.309000] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 01/23/2017] [Indexed: 12/14/2022]
Abstract
OBJECTIVE AUP1 (ancient ubiquitous protein 1) is an endoplasmic reticulum-associated protein that also localizes to the surface of lipid droplets (LDs), with dual role in protein quality control and LD regulation. Here, we investigated the role of AUP1 in hepatic lipid mobilization and demonstrate critical roles in intracellular biogenesis of apoB100 (apolipoprotein B-100), LD mobilization, and very-low-density lipoprotein (VLDL) assembly and secretion. APPROACH AND RESULTS: siRNA (short/small interfering RNA) knockdown of AUP1 significantly increased secretion of VLDL-sized apoB100-containing particles from HepG2 cells, correcting a key metabolic defect in these cells that normally do not secrete much VLDL. Secreted particles contained higher levels of metabolically labeled triglyceride, and AUP1-deficient cells displayed a larger average size of LDs, suggesting a role for AUP1 in lipid mobilization. Importantly, AUP1 was also found to directly interact with apoB100, and this interaction was enhanced with proteasomal inhibition. Knockdown of AUP1 reduced apoB100 ubiquitination, decreased intracellular degradation of newly synthesized apoB100, and enhanced extracellular apoB100 secretion. Interestingly, the stimulatory effect of AUP1 knockdown on VLDL assembly was reminiscent of the effect previously observed after MEK-ERK (mitogen-activated protein kinase kinase-extracellular signal-regulated kinase) inhibition; however, further studies indicated that the AUP1 effect was independent of MEK-ERK signaling. CONCLUSIONS In summary, our findings reveal an important role for AUP1 as a regulator of apoB100 stability, hepatic LD metabolism, and intracellular lipidation of VLDL particles. AUP1 may be a crucial factor in apoB100 quality control, determining the rate at which apoB100 is degraded or lipidated to enable VLDL particle assembly and secretion.
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Affiliation(s)
- Jing Zhang
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Mostafa Zamani
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Christoph Thiele
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Jennifer Taher
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Mohsen Amir Alipour
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Zemin Yao
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.)
| | - Khosrow Adeli
- From the Molecular Structure and Function Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada (J.Z., M.Z., J.T., K.A.); Department of Biochemistry (M.Z., K.A.) and Department of Laboratory Medicine and Pathobiology (J.T., K.A.), University of Toronto, Ontario, Canada; Biochemistry and Cell Biology of Lipids Unit, LIMES Institute, University of Bonn, Germany (C.T.); and Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ontario, Canada (M.A.A., Z.Y.).
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24
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Zamani M, Taher J, Adeli K. Complex role of autophagy in regulation of hepatic lipid and lipoprotein metabolism. J Biomed Res 2017; 31:377-385. [PMID: 27346467 PMCID: PMC5706430 DOI: 10.7555/jbr.30.20150137] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Discovering new therapeutic interventions to treat lipid and lipoprotein disorders is of great interest and the discovery of autophagy as a regulator of lipid metabolism has opened up new avenues for targeting modulators of this pathway. Autophagy is a degradative process that targets cellular components to the lysosome and recent studies have indicated a role for autophagy in regulating hepatic lipid metabolism (known as lipophagy) as well as lipoprotein assembly. Autophagy directly targets apolipoprotein B-100 (apoB100), the structural protein component of very low-density lipoproteins (VLDLs), and further targets lipid droplets (LDs), the cellular storage for neutral lipids. Autophagy thus plays a complex and dual role in VLDL particle assembly by regulating apoB100 degradation as well as aiding the maturation of VLDL particles by hydrolyzing lipid from LDs. The purpose of this article is to review our current understanding of molecular and cellular mechanisms mediating authophagic control of hepatic lipid biogenesis and VLDL production as well as dysregulation in insulin resistance and dyslipidemia.
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Affiliation(s)
- Mostafa Zamani
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.,Department of Biochemistry, University of Toronto, ON M5G 0A4, Canada
| | - Jennifer Taher
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, ON M5G 0A4, Canada
| | - Khosrow Adeli
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, ON M5G 0A4, Canada.,Department of Biochemistry, University of Toronto, ON M5G 0A4, Canada
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25
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Gordon SM, Pourmousa M, Sampson M, Sviridov D, Islam R, Perrin BS, Kemeh G, Pastor RW, Remaley AT. Identification of a novel lipid binding motif in apolipoprotein B by the analysis of hydrophobic cluster domains. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:135-145. [PMID: 27814978 DOI: 10.1016/j.bbamem.2016.10.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 10/11/2016] [Accepted: 10/27/2016] [Indexed: 02/05/2023]
Abstract
Apolipoprotein B (apoB) is a large amphipathic protein that is the structural scaffold for the formation of several classes of lipoproteins involved in lipid transport throughout the body. The goal of the present study was to identify specific domains in the apoB sequence that contribute to its lipid binding properties. A sequence analysis algorithm was developed to identify stretches of hydrophobic amino acids devoid of charged amino acids, which are referred to as hydrophobic cluster domains (HCDs). This analysis identified 78 HCDs in apoB with hydrophobic stretches ranging from 6 to 26 residues. Each HCD was analyzed in silico for secondary structure and lipid binding properties, and a subset was synthesized for experimental evaluation. One HCD peptide, B38, showed high affinity binding to both isolated HDL and LDL, and could exchange between lipoproteins. All-atom molecular dynamics simulations indicate that B38 inserts 3.7Å below the phosphate plane of the bilayer. B38 forms an unusual α-helix with a broad hydrophobic face and polar serine and threonine residues on the opposite face. Based on this structure, we hypothesized that B38 could efflux cholesterol from cells. B38 showed a 12-fold greater activity than the 5A peptide, a bihelical Class A amphipathic helix (EC50 of 0.2658 vs. 3.188μM; p<0.0001), in promoting cholesterol efflux from ABCA1 expressing BHK-1 cells. In conclusion, we have identified novel domains within apoB that contribute to its lipid biding properties. Additionally, we have discovered a unique amphipathic helix design for efficient ABCA1-specific cholesterol efflux.
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Affiliation(s)
- Scott M Gordon
- Lipoprotein Metabolism Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Mohsen Pourmousa
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD, USA
| | - Maureen Sampson
- Lipoprotein Metabolism Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Denis Sviridov
- Lipoprotein Metabolism Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Rafique Islam
- Lipoprotein Metabolism Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA; School of Systems Biology, George Mason University, Fairfax, VA, USA
| | - B Scott Perrin
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD, USA
| | - Georgina Kemeh
- Lipoprotein Metabolism Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Rockville, MD, USA
| | - Alan T Remaley
- Lipoprotein Metabolism Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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26
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Li Z, Xiong C, Mo S, Tian H, Yu M, Mao T, Chen Q, Luo H, Li Q, Lu J, Zhao Y, Li W. Comprehensive Transcriptome Analyses of the Fructose-Fed Syrian Golden Hamster Liver Provides Novel Insights into Lipid Metabolism. PLoS One 2016; 11:e0162402. [PMID: 27589064 PMCID: PMC5010245 DOI: 10.1371/journal.pone.0162402] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 07/21/2016] [Indexed: 01/08/2023] Open
Abstract
Dyslipidemia has been widely proven to contribute to cardiovascular diseases and other metabolic disorders, especially in insulin resistance and type 2 diabetes. The overproduction of VLDL is a significant characteristic of dyslipidemia, indicating the dysfunction of hepatic lipid metabolism, from triglyceride synthesis to transport. The fructose-fed Syrian golden hamster is an established animal model for the study of VLDL assembly with insulin resistance, however, it remains unknown how VLDL production is regulated at the transcriptional level due to the absence of a complete hamster genome. Here, we performed deep sequencing and constructed an mRNA-miRNA-lncRNA interaction network of Syrian golden hamster liver in order to reveal the global transcription profile and find potential RNA molecular regulation of VLDL production. We identified 4,450 novel multi-exon hamster lncRNAs and 755 miRNAs expressed in liver. Additionally, 146 differentially expressed coding genes, 27 differentially expressed lncRNA genes, as well as 16 differentially expressed miRNAs were identified. We then constructed an mRNA-miRNA-lncRNA interaction network that may potentially regulate VLDL production, and interestingly found several microRNA-centered regulatory networks. In order to verify our interpretation, miR-486 was selected for further experiments. Overexpression or down-regulation of miR-486 in fructose-fed hamsters resulted in altered hepatic expression of proteins involved in VLDL production, and in modulated levels of circulating VLDL. Our findings implicated that miR-486 is a potential regulator of circulating VLDL levels. These results provide new insights and a valuable resource for further study of the molecular mechanisms of VLDL secretion.
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Affiliation(s)
- Ziyang Li
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Chaoliang Xiong
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Suo Mo
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Haiying Tian
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Mengqian Yu
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Tingting Mao
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Qian Chen
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Haitao Luo
- Key Laboratory of Intelligent Information Processing, Advanced Computer Research Center, State Key Laboratory of Computer Architecture, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190, PR China
| | - Quanzhen Li
- Department of Immunology & Microarray Core Facility, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX, 75390, United States of America
| | - Jianxin Lu
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
- Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, 325035, PR China
| | - Yi Zhao
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
- Key Laboratory of Intelligent Information Processing, Advanced Computer Research Center, State Key Laboratory of Computer Architecture, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190, PR China
| | - Wei Li
- Key Laboratory of Laboratory Medicine, Ministry of Education of China, School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, 325035, PR China
- Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, 325035, PR China
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Zhang L, Wang HH. The essential functions of endoplasmic reticulum chaperones in hepatic lipid metabolism. Dig Liver Dis 2016; 48:709-16. [PMID: 27133206 DOI: 10.1016/j.dld.2016.03.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 03/06/2016] [Accepted: 03/22/2016] [Indexed: 12/11/2022]
Abstract
The endoplasmic reticulum (ER) is an essential organelle for protein and lipid synthesis in hepatocytes. ER homeostasis is vital to maintain normal hepatocyte physiology. Perturbed ER functions causes ER stress associated with accumulation of unfolded protein in the ER that activates a series of adaptive signalling pathways, termed unfolded protein response (UPR). The UPR regulates ER chaperone levels to preserve ER protein-folding environment to protect the cell from ER stress. Recent findings reveal an array of ER chaperones that alter the protein-folding environment in the ER of hepatocytes and contribute to dysregulation of hepatocyte lipid metabolism and liver disease. In this review, we will discuss the specific functions of these chaperones in regulation of lipid metabolism, especially de novo lipogenesis and lipid transport and demonstrate their homeostatic role not only for ER-protein synthesis but also for lipid metabolism in hepatocyte.
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Affiliation(s)
- LiChun Zhang
- Department of Emergency, Shengjing Affiliated Hospital of China Medical University, Shenyang, Liaoning Province, China.
| | - Hong-Hui Wang
- College of Biology, Hunan University, Changsha, Hunan Province, China.
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28
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Gui Y, Chu N, Qiu X, Tang W, Gober HJ, Li D, Wang L. 17-β-estradiol up-regulates apolipoprotein genes expression during osteoblast differentiation in vitro. Biosci Trends 2016; 10:140-51. [PMID: 27074899 DOI: 10.5582/bst.2016.01007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Apolipoproteins are of great physiological importance and are associated with different diseases. Many independent studies of patterns of gene expression during osteoblast differentiation have been described, and some apolipoproteins have been induced during this process. 17-β-estradiol (E2) may enhance osteoblast physiological function. However, no studies have indicated whether E2 can modulate the expression of apolipoproteins during osteoblast differentiation in vitro. The aim of the current study was to observe the regulation of apolipoprotein mRNA expression by E2 during this process. Primary osteoblasts were collected from the calvaria of newborn mice and were subjected to osteoblast differentiation in vitro with serial concentrations of E2. RNA was isolated on days 0, 5, and 25 of differentiation. Real-time PCR was performed to analyze the levels of apolipoprotein mRNA. Results showed that during osteoblast differentiation all of the apolipoprotein genes were up-regulated by E2 in a dose-dependent manner. Moreover, only ApoE was strongly induced during the mineralization of cultured osteoblasts. This result suggests that ApoE might be involved in osteoblast differentiation. The hypothesis is that E2 promotes osteoblast differentiation by up-regulating ApoE gene expression, though further study is needed to confirm this hypothesis.
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Affiliation(s)
- Yuyan Gui
- Laboratory for Reproductive Immunology, Hospital & Institute of Obstetrics and Gynecology, IBS, Fudan University Shanghai Medical College
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29
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Li M, Ye T, Wang XX, Li X, Qiang O, Yu T, Tang CW, Liu R. Effect of Octreotide on Hepatic Steatosis in Diet-Induced Obesity in Rats. PLoS One 2016; 11:e0152085. [PMID: 27002331 PMCID: PMC4803296 DOI: 10.1371/journal.pone.0152085] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 03/08/2016] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) caused by liver lipid dysregulation is linked to obesity. Somatostatin (SST) and its analogs have been used to treat pediatric hypothalamic obesity. However, the application of such drugs for the treatment of NAFLD has not been evaluated. OBJECTIVE This study aimed to investigate the expression levels of important regulators of hepatic lipid metabolism and the possible effect of the SST analog octreotide on these regulators. METHODS SD rats were assigned to a control group and a high-fat diet group. Obese rats from the high-fat diet group were further divided into the obese and octreotide-treated groups. The body weight, plasma SST, fasting plasma glucose (FPG), insulin, triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and free fatty acid (FFA) levels were measured. Hepatic steatosis was evaluated based on the liver TG content, HE staining and oil red O staining. The SREBP-1c, ACC1, FAS, MTP, apoB and ADRP expression levels in the liver were also determined by RT-PCR, qRT-PCR, western blot or ELISA. RESULTS The obese rats induced by high-fat diet expressed more SREBP-1c, FAS and ADRP but less MTP protein in the liver than those of control rats, whereas octreotide intervention reversed these changes and increased the level of apoB protein. Compared to the control group, obese rats showed increased liver ACC1, SREBP-1c and apoB mRNA levels, whereas octreotide-treated rats showed decreased mRNA levels of apoB and SREBP-1c. This was accompanied by increased body weight, liver TG contents, FPG, TG, TC, LDL-C, FFA, insulin and derived homeostatic model assessment (HOMA) values. Octreotide intervention significantly decreased these parameters. Compared to the control group, the obese group showed a decreasing trend on plasma SST levels, which were significantly increased by the octreotide intervention. CONCLUSION Octreotide can ameliorate hepatic steatosis in obese rats, possibly by decreasing hepatic lipogenesis and increasing TG export from hepatocytes.
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Affiliation(s)
- Mao Li
- Division of Peptides Related to Human Disease, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China.,Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu, China
| | - Ting Ye
- Division of Peptides Related to Human Disease, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China.,Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu, China
| | - Xiao-Xia Wang
- Division of Peptides Related to Human Disease, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China.,Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu, China
| | - Xian Li
- Division of Peptides Related to Human Disease, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Ou Qiang
- Division of Peptides Related to Human Disease, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
| | - Tao Yu
- Division of Peptides Related to Human Disease, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China.,Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu, China
| | - Cheng-Wei Tang
- Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu, China
| | - Rui Liu
- Division of Peptides Related to Human Disease, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
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30
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Jiang ZG, Tsugawa Y, Tapper EB, Lai M, Afdhal N, Robson SC, Mukamal KJ. Low-fasting triglyceride levels are associated with non-invasive markers of advanced liver fibrosis among adults in the United States. Aliment Pharmacol Ther 2015; 42:106-16. [PMID: 25913437 DOI: 10.1111/apt.13216] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 02/22/2015] [Accepted: 04/08/2015] [Indexed: 02/06/2023]
Abstract
BACKGROUND Elevated fasting triglyceride is often associated with metabolic syndrome and non-alcoholic fatty liver disease (NAFLD), the most common form of chronic liver disease. On the other hand, as liver disease progresses, patients may develop hepatocellular dysfunction that impairs triglyceride production. AIM To test the hypothesis that lower fasting triglyceride levels may paradoxically indicate more advanced liver disease. METHODS A cross-sectional analysis of 11 947 adults aged 20 years or older without chronic viral hepatitis from the National Health and Nutrition Examination Survey 1999-2010 was performed to analyze the relationships between fasting triglyceride levels and five validated non-invasive indices of liver fibrosis, including Fibrosis 4 Score (FIB4), NAFLD Fibrosis Score (NFS), Ast-Platelet Ration Index, AST/ALT ratio and BARD. RESULTS Low-fasting triglyceride levels were consistently associated with elevated liver fibrosis indices. Individuals in the lowest quintile of triglycerides (TG) had an adjusted odds ratio (OR) of 3.0 (95% CI, 1.7-5.2; P < 0.001) for advanced fibrosis estimated by FIB4 score and OR of 1.8 (95% Cl, 1.2-2.7; P = 0.009) estimated by NFS, compared to individuals in the highest quintile. This association remained highly significant when restricted to individuals with abnormal LFTs from suspected NAFLD. This inverse relationship was continuous, and more pronounced among men and whites (P interaction <0.001 and 0.008 respectively), but not modified by age or body mass index. In addition, fasting TG had a stronger, more direct association with liver fibrosis indices than did albumin or total bilirubin. CONCLUSIONS Fasting triglyceride levels were inversely associated with liver fibrosis indicators in American adults, especially among white men. Our findings suggest that sequential lipid measurements may serve as a useful disease marker in the management of chronic liver disease patients.
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Affiliation(s)
- Z G Jiang
- Division of Gastroenterology and Hepatology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - Y Tsugawa
- Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, Boston, MA, USA.,Harvard Interfaculty Initiative in Health Policy, Cambridge, MA, USA
| | - E B Tapper
- Division of Gastroenterology and Hepatology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - M Lai
- Division of Gastroenterology and Hepatology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - N Afdhal
- Division of Gastroenterology and Hepatology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - S C Robson
- Division of Gastroenterology and Hepatology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - K J Mukamal
- Harvard Medical School, Boston, MA, USA.,Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center, Boston, MA, USA
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31
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Activation of hepatic CREBH and Insig signaling in the anti-hypertriglyceridemic mechanism of R-α-lipoic acid. J Nutr Biochem 2015; 26:921-8. [PMID: 26007286 DOI: 10.1016/j.jnutbio.2015.03.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 03/15/2015] [Accepted: 03/24/2015] [Indexed: 12/12/2022]
Abstract
The activation of sterol regulatory element binding proteins (SREBPs) is regulated by insulin-induced genes 1 and 2 (Insig-1 and Insig-2) and SCAP. We previously reported that feeding R-α-lipoic acid (LA) to Zucker diabetic fatty (ZDF) rats improves severe hypertriglyceridemia. In this study, we investigated the role of cyclic AMP-responsive element binding protein H (CREBH) in the lipid-lowering mechanism of LA and its involvement in the SREBP-1c and Insig pathway. Incubation of McA cells with LA (0.2 mM) or glucose (6 mM) stimulated activation of CREBH. LA treatment further induced mRNA expression of Insig-1 and Insig-2a, but not Insig-2b, in glucose-treated cells. In vivo, feeding LA to obesity-induced hyperlipidemic ZDF rats activated hepatic CREBH and stimulated transcription and translation of Insig-1 and Insig-2a. Activation of CREBH and Insigs induced by LA suppressed processing of SREBP-1c precursor into nuclear SREBP-1c, which subsequently inhibited expression of genes involved in fatty acid synthesis, including FASN, ACC and SCD-1, and reduced triglyceride (TG) contents in both glucose-treated cells and ZDF rat livers. Additionally, LA treatment also decreased abundances of very low density lipoprotein (VLDL)-associated apolipoproteins, apoB100 and apoE, in glucose-treated cells and livers of ZDF rats, leading to decreased secretion of VLDL and improvement of hypertriglyceridemia. This study unveils a novel molecular mechanism whereby LA lowers TG via activation of hepatic CREBH and increased expression of Insig-1 and Insig-2a to inhibit de novo lipogenesis and VLDL secretion. These findings provide novel insight into the therapeutic potential of LA as an anti-hypertriglyceridemia dietary molecule.
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32
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Abstract
The past decade has witnessed steady and rapid progress in HCV research, which has led to the recent breakthrough in therapies against this significant human pathogen. Yet a deeper understanding of the life cycle of the virus is required to develop more affordable treatments and to advance vaccine design. HCV entry presents both a challenge for scientific research and an opportunity for alternative intervention approaches, owning to its highly complex nature and the myriad of players involved. More than half a dozen cellular proteins are implicated in HCV entry; and a more definitive picture regarding the structures of the glycoproteins is emerging. A role of apolipoproteins in HCV entry has also been established. Still, major questions remain, and the answers to these, which we summarize in this review, will hopefully close the gaps in our understanding and complete the puzzle that is HCV entry.
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Affiliation(s)
- Sarah C Ogden
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA
| | - Hengli Tang
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA ; Institute of Health Sciences, Anhui University, Hefei, 230601, PR China
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33
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New insights into the pathophysiology of dyslipidemia in type 2 diabetes. Atherosclerosis 2015; 239:483-95. [PMID: 25706066 DOI: 10.1016/j.atherosclerosis.2015.01.039] [Citation(s) in RCA: 256] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 01/28/2015] [Accepted: 01/30/2015] [Indexed: 02/06/2023]
Abstract
Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality for patients with type 2 diabetes, despite recent significant advances in management strategies to lessen CVD risk factors. A major cause is the atherogenic dyslipidemia, which consists of elevated plasma concentrations of both fasting and postprandial triglyceride-rich lipoproteins (TRLs), small dense low-density lipoprotein (LDL) and low high-density lipoprotein (HDL) cholesterol. The different components of diabetic dyslipidemia are not isolated abnormalities but closely linked to each other metabolically. The underlying disturbances are hepatic overproduction and delayed clearance of TRLs. Recent results have unequivocally shown that triglyceride-rich lipoproteins and their remnants are atherogenic. To develop novel strategies for the prevention and treatment of dyslipidaemia, it is essential to understand the pathophysiology of dyslipoproteinaemia in humans. Here, we review recent advances in our understanding of the pathophysiology of diabetic dyslipidemia.
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34
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Wang S, Park S, Kodali VK, Han J, Yip T, Chen Z, Davidson NO, Kaufman RJ. Identification of protein disulfide isomerase 1 as a key isomerase for disulfide bond formation in apolipoprotein B100. Mol Biol Cell 2014; 26:594-604. [PMID: 25518935 PMCID: PMC4325832 DOI: 10.1091/mbc.e14-08-1274] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pdi1 knockdown decreases apoB100 synthesis, reduces MTP activity and apoB100 lipidation, and impairs the oxidative folding of apoB100, which causes defective VLDL secretion. PDI1 promotes formation of disulfide bonds in apoB100 and serves as its disulfide isomerase. Apolipoprotein (apo) B is an obligatory component of very low density lipoprotein (VLDL), and its cotranslational and posttranslational modifications are important in VLDL synthesis, secretion, and hepatic lipid homeostasis. ApoB100 contains 25 cysteine residues and eight disulfide bonds. Although these disulfide bonds were suggested to be important in maintaining apoB100 function, neither the specific oxidoreductase involved nor the direct role of these disulfide bonds in apoB100-lipidation is known. Here we used RNA knockdown to evaluate both MTP-dependent and -independent roles of PDI1 in apoB100 synthesis and lipidation in McA-RH7777 cells. Pdi1 knockdown did not elicit any discernible detrimental effect under normal, unstressed conditions. However, it decreased apoB100 synthesis with attenuated MTP activity, delayed apoB100 oxidative folding, and reduced apoB100 lipidation, leading to defective VLDL secretion. The oxidative folding–impaired apoB100 was secreted mainly associated with LDL instead of VLDL particles from PDI1-deficient cells, a phenotype that was fully rescued by overexpression of wild-type but not a catalytically inactive PDI1 that fully restored MTP activity. Further, we demonstrate that PDI1 directly interacts with apoB100 via its redox-active CXXC motifs and assists in the oxidative folding of apoB100. Taken together, these findings reveal an unsuspected, yet key role for PDI1 in oxidative folding of apoB100 and VLDL assembly.
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Affiliation(s)
- Shiyu Wang
- Degenerative Diseases Research Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
| | - Shuin Park
- Degenerative Diseases Research Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
| | - Vamsi K Kodali
- Degenerative Diseases Research Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
| | - Jaeseok Han
- Soonchunhyang Institute of Med-Bio Science, Soonchunhayng University, Cheonan-si, Choongchengnam-do 330-930, Republic of Korea
| | - Theresa Yip
- Degenerative Diseases Research Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
| | - Zhouji Chen
- Division of Geriatrics and Nutrition Sciences, Washington University School of Medicine, St. Louis, MO 63110
| | - Nicholas O Davidson
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110
| | - Randal J Kaufman
- Degenerative Diseases Research Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037
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35
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Abstract
Autophagy is an essential cellular pathway by which protein aggregates, long-lived proteins, or defective organelles are sequestered in double membrane vesicles and then degraded upon fusion of those vesicles with lysosomes. Although autophagy plays a critical role in maintaining intracellular homeostasis and keeping the cell in a healthy state, this key pathway can become dysregulated in various cardiometabolic disorders, such as; obesity, dyslipidemia, inflammation, and insulin resistance. In these conditions, autophagy may actually worsen the pathological state instead of protecting the cell or organism. In this review, we discuss how dysregulated autophagy may be linked to increases in cardiovascular risk factors, and how manipulation of the autophagic machinery might reduce those risks.
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Affiliation(s)
- Juan G. Juárez-Rojas
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY USA
- Endocrinolgy Department, National Institute of Cardiology “Ignacio Chávez”, Mexico City, Mexico
| | - Gissette Reyes-Soffer
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY USA
| | - Donna Conlon
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY USA
| | - Henry N. Ginsberg
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY USA
- PH10-305, Irving Institute for Clinical and Translational Research, 630 West 168 Street, New York, NY 10032 USA
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36
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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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37
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Christian P, Su Q. MicroRNA regulation of mitochondrial and ER stress signaling pathways: implications for lipoprotein metabolism in metabolic syndrome. Am J Physiol Endocrinol Metab 2014; 307:E729-37. [PMID: 25184990 DOI: 10.1152/ajpendo.00194.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The development of metabolic syndrome is closely associated with the deregulation of lipid metabolism. Emerging evidence has demonstrated that microRNAs (miRNAs) are intensively engaged in lipid and lipoprotein metabolism by regulating genes involved in control of intracellular lipid synthesis, mitochondrial fatty acid oxidation, and lipoprotein assembly. Mitochondrial dysfunction induced by altered miRNA expression has been proposed to be a contributing factor in the onset of metabolic diseases, while at the same time, aberrant expression of certain miRNAs is associated with the induction of endoplasmic reticulum (ER) stress induced by nutrient-surplus. These studies position miRNAs as a link between oxidative stress and ER stress, two cellular stress pathways that are deregulated in metabolic disease and are associated with very-low-density lipoprotein (VLDL) overproduction. Dyslipoproteinemia frequently accompanied with metabolic syndrome is initiated largely by the overproduction of VLDL and altered biogenesis of high-density lipoprotein (HDL). In this review, we highlight recent findings on the regulatory impact of miRNAs on the metabolic homeostasis of mitochondria and ER as well as their contribution to the aberrant biogenesis of both VLDL and HDL in the context of metabolic disorders, in an attempt to gain further insights into the molecular mechanisms of dyslipidemia in the metabolic syndrome.
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Affiliation(s)
- Patricia Christian
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Qiaozhu Su
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska
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38
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Zhang LJ, Wang C, Yuan Y, Wang H, Wu J, Liu F, Li L, Gao X, Zhao YL, Hu PZ, Li P, Ye J. Cideb facilitates the lipidation of chylomicrons in the small intestine. J Lipid Res 2014; 55:1279-87. [PMID: 24831470 DOI: 10.1194/jlr.m046482] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Indexed: 02/01/2023] Open
Abstract
Cell death-inducing DFF45-like effector b (Cideb), an endoplasmic reticulum (ER)- and lipid droplet (LD)-associated protein, has been shown to play a critical role in maintaining hepatic lipid homeostasis by promoting the lipidation and maturation of VLDL particles. Here, we observed that Cideb is expressed in the jejunum and ileum sections of the small intestine, and its expression was induced by high-fat diet. Intragastric gavage with lipids resulted in the retention of lipids in the intestine in Cideb-deficient mice. In addition, we observed that mice with Cideb deficiency exhibited reduced intestinal chylomicron-TG secretion and increased lipid accumulation in the enterocytes. The sizes of chylomicrons secreted from the small intestine of Cideb-deficient mice were also smaller than those from wild-type mice. Furthermore, the overexpression of Cideb increased TG secretion and reduced lipid accumulation in the enterocyte-like Caco-2 cells. In addition, we proved that Cideb was localized to the ER and LDs and could interact with ApoB48 in Caco-2 cells. Overall, these data revealed that Cideb plays an important role in controlling intestinal chylomicron lipidation.
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Affiliation(s)
- Li-Jun Zhang
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China Department of Clinical Diagnosis, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, China
| | - Chao Wang
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China Department of Clinical Diagnosis, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, China
| | - Yuan Yuan
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Hui Wang
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Jie Wu
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Fang Liu
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Le Li
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Xing Gao
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Yuan-Lin Zhao
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Pei-Zhen Hu
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Peng Li
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 10084, China
| | - Jing Ye
- Department of Pathology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
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39
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Abstract
PURPOSE OF REVIEW The endoplasmic reticulum (ER) maintains cellular metabolic homeostasis by coordinating protein synthesis, secretion activities, lipid biosynthesis and calcium (Ca²⁺) storage. In this review, we will discuss how altered ER homeostasis contributes to dysregulation of hepatic lipid metabolism and contributes to liver-associated metabolic diseases. RECENT FINDINGS Perturbed ER functions or accumulation of unfolded protein in the ER leads to the activation of the unfolded protein response (UPR) to protect the cell from ER stress. Recent findings pinpoint the key regulatory role of the UPR in hepatic lipid metabolism and demonstrate the potential causal mechanism of ER stress in metabolic dysregulation including diabetes and obesity. SUMMARY A wide range of factors can alter the protein-folding environment in the ER of hepatocytes and contribute to dysregulation of hepatic lipid metabolism and liver disease. The UPR constitutes a series of adaptive programs that preserve ER protein-folding environment and maintain hepatic lipid homeostasis. Signaling components of the UPR are emerging as potential targets for intervention and treatment of human liver-associated metabolic diseases.
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Affiliation(s)
- Shiyu Wang
- Degenerative Disease Research, Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, California, USA
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40
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Fisher E, Lake E, McLeod RS. Apolipoprotein B100 quality control and the regulation of hepatic very low density lipoprotein secretion. J Biomed Res 2014; 28:178-93. [PMID: 25013401 PMCID: PMC4085555 DOI: 10.7555/jbr.28.20140019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 02/15/2014] [Indexed: 12/19/2022] Open
Abstract
Apolipoprotein B (apoB) is the main protein component of very low density lipoprotein (VLDL) and is necessary for the assembly and secretion of these triglyceride (TG)-rich particles. Following release from the liver, VLDL is converted to low density lipoprotein (LDL) in the plasma and increased production of VLDL can therefore play a detrimental role in cardiovascular disease. Increasing evidence has helped to establish VLDL assembly as a target for the treatment of dyslipidemias. Multiple factors are involved in the folding of the apoB protein and the formation of a secretion-competent VLDL particle. Failed VLDL assembly can initiate quality control mechanisms in the hepatocyte that target apoB for degradation. ApoB is a substrate for endoplasmic reticulum associated degradation (ERAD) by the ubiquitin proteasome system and for autophagy. Efficient targeting and disposal of apoB is a regulated process that modulates VLDL secretion and partitioning of TG. Emerging evidence suggests that significant overlap exists between these degradative pathways. For example, the insulin-mediated targeting of apoB to autophagy and postprandial activation of the unfolded protein response (UPR) may employ the same cellular machinery and regulatory cues. Changes in the quality control mechanisms for apoB impact hepatic physiology and pathology states, including insulin resistance and fatty liver. Insulin signaling, lipid metabolism and the hepatic UPR may impact VLDL production, particularly during the postprandial state. In this review we summarize our current understanding of VLDL assembly, apoB degradation, quality control mechanisms and the role of these processes in liver physiology and in pathologic states.
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Affiliation(s)
- Eric Fisher
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Elizabeth Lake
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Roger S McLeod
- Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, Canada
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Delporte C, Boudjeltia KZ, Noyon C, Furtmüller PG, Nuyens V, Slomianny MC, Madhoun P, Desmet JM, Raynal P, Dufour D, Koyani CN, Reyé F, Rousseau A, Vanhaeverbeek M, Ducobu J, Michalski JC, Nève J, Vanhamme L, Obinger C, Malle E, Van Antwerpen P. Impact of myeloperoxidase-LDL interactions on enzyme activity and subsequent posttranslational oxidative modifications of apoB-100. J Lipid Res 2014; 55:747-57. [PMID: 24534704 DOI: 10.1194/jlr.m047449] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Oxidation of LDL by the myeloperoxidase (MPO)-H2O2-chloride system is a key event in the development of atherosclerosis. The present study aimed at investigating the interaction of MPO with native and modified LDL and at revealing posttranslational modifications on apoB-100 (the unique apolipoprotein of LDL) in vitro and in vivo. Using amperometry, we demonstrate that MPO activity increases up to 90% when it is adsorbed at the surface of LDL. This phenomenon is apparently reflected by local structural changes in MPO observed by circular dichroism. Using MS, we further analyzed in vitro modifications of apoB-100 by hypochlorous acid (HOCl) generated by the MPO-H2O2-chloride system or added as a reagent. A total of 97 peptides containing modified residues could be identified. Furthermore, differences were observed between LDL oxidized by reagent HOCl or HOCl generated by the MPO-H2O2-chloride system. Finally, LDL was isolated from patients with high cardiovascular risk to confirm that our in vitro findings are also relevant in vivo. We show that several HOCl-mediated modifications of apoB-100 identified in vitro were also present on LDL isolated from patients who have increased levels of plasma MPO and MPO-modified LDL. In conclusion, these data emphasize the specificity of MPO to oxidize LDL.
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Affiliation(s)
- Cédric Delporte
- Laboratory of Pharmaceutical Chemistry Faculty of Pharmacy, Université Libre de Bruxelles, Brussels, Belgium
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42
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Permenter MG, Dennis WE, Sutto TE, Jackson DA, Lewis JA, Stallings JD. Exposure to cobalt causes transcriptomic and proteomic changes in two rat liver derived cell lines. PLoS One 2013; 8:e83751. [PMID: 24386269 PMCID: PMC3875483 DOI: 10.1371/journal.pone.0083751] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 11/07/2013] [Indexed: 12/23/2022] Open
Abstract
Cobalt is a transition group metal present in trace amounts in the human diet, but in larger doses it can be acutely toxic or cause adverse health effects in chronic exposures. Its use in many industrial processes and alloys worldwide presents opportunities for occupational exposures, including military personnel. While the toxic effects of cobalt have been widely studied, the exact mechanisms of toxicity remain unclear. In order to further elucidate these mechanisms and identify potential biomarkers of exposure or effect, we exposed two rat liver-derived cell lines, H4-II-E-C3 and MH1C1, to two concentrations of cobalt chloride. We examined changes in gene expression using DNA microarrays in both cell lines and examined changes in cytoplasmic protein abundance in MH1C1 cells using mass spectrometry. We chose to closely examine differentially expressed genes and proteins changing in abundance in both cell lines in order to remove cell line specific effects. We identified enriched pathways, networks, and biological functions using commercial bioinformatic tools and manual annotation. Many of the genes, proteins, and pathways modulated by exposure to cobalt appear to be due to an induction of a hypoxic-like response and oxidative stress. Genes that may be differentially expressed due to a hypoxic-like response are involved in Hif-1α signaling, glycolysis, gluconeogenesis, and other energy metabolism related processes. Gene expression changes linked to oxidative stress are also known to be involved in the NRF2-mediated response, protein degradation, and glutathione production. Using microarray and mass spectrometry analysis, we were able to identify modulated genes and proteins, further elucidate the mechanisms of toxicity of cobalt, and identify biomarkers of exposure and effect in vitro, thus providing targets for focused in vivo studies.
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Affiliation(s)
| | - William E. Dennis
- US Army Center for Environmental Health Research, Fort Detrick, Maryland, United States of America
| | - Thomas E. Sutto
- Naval Research Laboratory, Washington, District of Columbia, United States of America
| | - David A. Jackson
- US Army Center for Environmental Health Research, Fort Detrick, Maryland, United States of America
| | - John A. Lewis
- US Army Center for Environmental Health Research, Fort Detrick, Maryland, United States of America
| | - Jonathan D. Stallings
- US Army Center for Environmental Health Research, Fort Detrick, Maryland, United States of America
- * E-mail:
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43
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Abstract
Cardiovascular disease represents the most common cause of death in patients with nonalcoholic fatty liver disease (NAFLD). Patients with NAFLD exhibit an atherogenic dyslipidemia that is characterized by an increased plasma concentration of triglycerides, reduced concentration of high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) particles that are smaller and more dense than normal. The pathogenesis of NAFLD-associated atherogenic dyslipidemia is multifaceted, but many aspects are attributable to manifestations of insulin resistance. Here the authors review the structure, function, and metabolism of lipoproteins, which are macromolecular particles of lipids and proteins that transport otherwise insoluble triglyceride and cholesterol molecules within the plasma. They provide a current explanation of the metabolic perturbations that are observed in the setting of insulin resistance. An improved understanding of the pathophysiology of atherogenic dyslipidemia would be expected to guide therapies aimed at reducing morbidity and mortality in patients with NAFLD.
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Affiliation(s)
- Edward Fisher
- Division of Cardiology, Department of Medicine, The Marc and Ruti Bell Program in Vascular Biology, New York University School of Medicine, New York, New York
| | - David Cohen
- Division of Gastroenterology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
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44
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Wei HS, Wei HL, Zhao F, Zhong LP, Zhan YT. Glycosyltransferase GLT8D2 positively regulates ApoB100 protein expression in hepatocytes. Int J Mol Sci 2013; 14:21435-46. [PMID: 24173238 PMCID: PMC3856013 DOI: 10.3390/ijms141121435] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 09/11/2013] [Accepted: 09/12/2013] [Indexed: 12/18/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is characterized by triglyceride (TG) accumulation in hepatocytes. Very low density lipoprotein (VLDL) is a major secretory product of the liver that transports endogenously synthesized TG. Disrupted VLDL secretion may contribute to the accumulation of TG in hepatocytes. ApoB100 (apolipoprotein B100) is a glycoprotein and an essential protein component of VLDL. Its glycosylation may affect VLDL assembly and secretion. However, which glycosyltransferase catalyzes apoB100 glycosylation is unknown. In this study, we cloned the GLT8D2 (glycosyltransferase 8 domain containing 2) gene from HepG2 cells and generated a series of plasmids for in vitro studies of its molecular functions. We discovered that GLT8D2 was localized in the ER, interacted with apoB100, and positively regulated the levels of apoB100 protein in HepG2 cells. Based on these results, we propose that GLT8D2 is a glycosyltransferase of apoB100 that regulates apoB100 levels in hepatocytes.
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Affiliation(s)
- Hong-Shan Wei
- Institutes of Infectious Disease, Beijing Ditan Hospital, Capital Medical University, Beijing 100015, China; E-Mail:
| | - Hong-Lian Wei
- Seventh Department of Internal Medicine, Linyi People’s Hospital, Linyi 276000, Shandong, China; E-Mail:
- Department of Gastroenterology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China; E-Mails: (F.Z.); (L.-P.Z.)
| | - Fei Zhao
- Department of Gastroenterology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China; E-Mails: (F.Z.); (L.-P.Z.)
| | - Le-Ping Zhong
- Department of Gastroenterology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China; E-Mails: (F.Z.); (L.-P.Z.)
| | - Yu-Tao Zhan
- Department of Gastroenterology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China; E-Mails: (F.Z.); (L.-P.Z.)
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45
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Low-density lipoprotein modified by myeloperoxidase in inflammatory pathways and clinical studies. Mediators Inflamm 2013; 2013:971579. [PMID: 23983406 PMCID: PMC3742028 DOI: 10.1155/2013/971579] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 06/26/2013] [Indexed: 02/07/2023] Open
Abstract
Oxidation of low-density lipoprotein (LDL) has a key role in atherogenesis. Among the different models of oxidation that have been studied, the one using myeloperoxidase (MPO) is thought to be more physiopathologically relevant. Apolipoprotein B-100 is the unique protein of LDL and is the major target of MPO. Furthermore, MPO rapidly adsorbs at the surface of LDL, promoting oxidation of amino acid residues and formation of oxidized lipoproteins that are commonly named Mox-LDL. The latter is not recognized by the LDL receptor and is accumulated by macrophages. In the context of atherogenesis, Mox-LDL accumulates in macrophages leading to foam cell formation. Furthermore, Mox-LDL seems to have specific effects and triggers inflammation. Indeed, those oxidized lipoproteins activate endothelial cells and monocytes/macrophages and induce proinflammatory molecules such as TNFα and IL-8. Mox-LDL may also inhibit fibrinolysis mediated via endothelial cells and consecutively increase the risk of thrombus formation. Finally, Mox-LDL has been involved in the physiopathology of several diseases linked to atherosclerosis such as kidney failure and consequent hemodialysis therapy, erectile dysfunction, and sleep restriction. All these issues show that the investigations of MPO-dependent LDL oxidation are of importance to better understand the inflammatory context of atherosclerosis.
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46
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Rutledge AC, Qiu W, Zhang R, Urade R, Adeli K. Role of cysteine-protease CGHC motifs of ER-60, a protein disulfide isomerase, in hepatic apolipoprotein B100 degradation. Arch Biochem Biophys 2013; 537:104-12. [PMID: 23827315 DOI: 10.1016/j.abb.2013.06.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 06/20/2013] [Accepted: 06/21/2013] [Indexed: 11/30/2022]
Abstract
Apolipoprotein B100 (apoB), the structural component of very low density lipoproteins (VLDL), is susceptible to misfolding and subsequent degradation by several intracellular pathways. ER-60, which has been implicated in apoB degradation, is a protein disulfide isomerase (PDI) that forms or rearranges disulfide bonds in substrate proteins and also possesses cysteine protease activity. To determine which ER-60 function is important for apoB degradation, adenoviruses encoding wild-type human ER-60 or a mutant form of human ER-60 (C60A, C409A) that lacked cysteine protease activity were overexpressed in HepG2 cells. Overexpression of wild-type ER-60 in HepG2 cells promoted apoB degradation and impaired apoB secretion, but mutant ER-60 overexpression did not. In McArdle RH-7777 cells, VLDL secretion was markedly inhibited following overexpression of wild-type but not mutant ER-60, an effect that could be blocked by oleate treatment. Mutant ER-60 was not trapped on apoB as it was with the control substrate tapasin, suggesting that ER-60's role in apoB degradation is likely unrelated to its protein disulfide isomerase activity. Thus, ER-60 may participate in apoB degradation by acting as a cysteine protease. We postulate that apoB cleavage by ER-60 within the ER lumen could facilitate proteasomal degradation of the C-terminus of translocationally-arrested apoB.
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Affiliation(s)
- Angela C Rutledge
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
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Christian P, Sacco J, Adeli K. Autophagy: Emerging roles in lipid homeostasis and metabolic control. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:819-24. [PMID: 23274236 DOI: 10.1016/j.bbalip.2012.12.009] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 12/13/2012] [Accepted: 12/18/2012] [Indexed: 02/06/2023]
Abstract
Current evidence implicates autophagy in the regulation of lipid stores within the two main organs involved in maintaining lipid homeostasis, the liver and adipose tissue. Critical to this role in hepatocytes is the breakdown of cytoplasmic lipid droplets, a process referred to as lipophagy. Conversely, autophagy is required for adipocyte differentiation and the concurrent accumulation of lipid droplets. Autophagy also affects lipid metabolism through contributions to lipoprotein assembly. A number of reports have now implicated autophagy in the degradation of apolipoprotein B, the main structural protein of very-low-density-lipoprotein. Aberrant autophagy may also be involved in conditions of deregulated lipid homeostasis in metabolic disorders such as the metabolic syndrome. First, insulin signalling and autophagy activity appear to diverge in a mechanism of reciprocal regulation, suggesting a role for autophagy in insulin resistance. Secondly, upregulation of autophagy may lead to conversion of white adipose tissue into brown adipose tissue, thus regulating energy expenditure and obesity. Thirdly, upregulation of autophagy in hepatocytes could increase breakdown of lipid stores controlling triglyceride homeostasis and fatty liver. Taken together, autophagy appears to play a very complex role in lipid homeostasis, affecting lipid stores differently depending on the tissue, as well as contributing to pathways of lipoprotein metabolism.
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Affiliation(s)
- Patricia Christian
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8
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49
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Morris EM, Meers GME, Booth FW, Fritsche KL, Hardin CD, Thyfault JP, Ibdah JA. PGC-1α overexpression results in increased hepatic fatty acid oxidation with reduced triacylglycerol accumulation and secretion. Am J Physiol Gastrointest Liver Physiol 2012; 303:G979-92. [PMID: 22899824 PMCID: PMC3469696 DOI: 10.1152/ajpgi.00169.2012] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Studies have shown that decreased mitochondrial content and function are associated with hepatic steatosis. We examined whether peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) overexpression and a subsequent increase in mitochondrial content and function in rat primary hepatocytes (in vitro) and Sprague-Dawley rats (in vivo) would comprehensively alter mitochondrial lipid metabolism, including complete (CO(2)) and incomplete (acid-soluble metabolites) fatty acid oxidation (FAO), tricarboxylic acid cycle flux, and triacylglycerol (TAG) storage and export. PGC-1α overexpression in primary hepatocytes produced an increase in markers of mitochondrial content and function (citrate synthase, mitochondrial DNA, and electron transport system complex proteins) and an increase in FAO, which was accompanied by reduced TAG storage and TAG secretion compared with control. Also, the PGC-1α-overexpressing hepatocytes were protected from excess TAG accumulation following overnight lipid treatment. PGC-1α overexpression in hepatocytes lowered expression of genes critical to VLDL assembly and secretion (apolipoprotein B and microsomal triglyceride transfer protein). Adenoviral transduction of rats with PGC-1α resulted in a liver-specific increase in PGC-1α expression and produced an in vivo liver phenotype of increased FAO via increased mitochondrial function that also resulted in reduced hepatic TAG storage and decreased plasma TAG levels. In conclusion, overexpression of hepatic PGC-1α and subsequent increases in FAO through elevated mitochondrial content and/or function result in reduced TAG storage and secretion in the in vitro and in vivo milieu.
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Affiliation(s)
- E. Matthew Morris
- 1Department of Internal Medicine-Gastroenterology, University of Missouri, Columbia, Missouri;
| | - Grace M. E. Meers
- 1Department of Internal Medicine-Gastroenterology, University of Missouri, Columbia, Missouri;
| | - Frank W. Booth
- 2Department of Biomedical Science, University of Missouri, Columbia, Missouri; ,5Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; and
| | - Kevin L. Fritsche
- 3Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; ,4Department of Animal Sciences, University of Missouri, Columbia, Missouri;
| | - Christopher D. Hardin
- 3Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri;
| | - John P. Thyfault
- 1Department of Internal Medicine-Gastroenterology, University of Missouri, Columbia, Missouri; ,3Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; ,6Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri
| | - Jamal A. Ibdah
- 1Department of Internal Medicine-Gastroenterology, University of Missouri, Columbia, Missouri; ,3Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; ,5Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; and ,6Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri
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50
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Evangelisti C, Bianco F, Pradella LM, Puliti A, Goldoni A, Sbrana I, Rossi M, Vargiolu M, Seri M, Romeo G, Stanghellini V, de Giorgio R, Bonora E. Apolipoprotein B is a new target of the GDNF/RET and ET-3/EDNRB signalling pathways. Neurogastroenterol Motil 2012; 24:e497-508. [PMID: 22897442 DOI: 10.1111/j.1365-2982.2012.01998.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
BACKGROUND GDNF/RET and Endothelin-3 (ET-3)/EDNRB regulate survival, differentiation, migration, and proliferation of neural crest-derived cells. Although several RET and EDNRB signalling mediators have been characterized, most of the genes targeted by these two pathways are still largely unknown. We focused our study on apolipoprotein B (APOB) as a novel target gene of the RET and EDNRB pathways, based on previous data obtained using a Caenorhabditis elegans strain mutant for the homologue of mammalian ECE1. METHODS Molecular and cellular studies of Apob were performed in the murine Neuro2a cells, an in vitro model for studying neural crest-derived cell development, along with a mouse knock-in for the Hirschsprung-associated mutation Ret(C620R). Silencing for Apob and Ret has been performed via shRNA. KEY RESULTS GDNF/RET and ET-3/EDNRB cooperated in inducing neuronal differentiation resulting in Apob activation in Neuro2a cell line. Apob expression was downregulated in mouse embryos homozygous for the Ret(C620R) mutation and presenting a severe Hirschsprung phenotype. Ret silencing prevented Apob expression increase. MAPK P38 kinase activation evoked Apob expression via GDNF/RET signalling in Neuro2a cells. A p53-dependent repressor element in Apob promoter resulted in a reduced Apob expression. Silencing of Apob reduced HuD protein expression. CONCLUSIONS & INFERENCES Apob is a novel downstream target of the RET/EDNRB pathways with a role in neuronal survival and maintenance, as indicated by its effect on HuD expression. Our data provide a conceptual framework to investigate and establish the role of APOB gene in severe gut dysmotility.
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Affiliation(s)
- C Evangelisti
- Medical Genetics Unit, St.Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
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