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Zhang Y, Fang XM. The pan-liver network theory: From traditional chinese medicine to western medicine. CHINESE J PHYSIOL 2023; 66:401-436. [PMID: 38149555 DOI: 10.4103/cjop.cjop-d-22-00131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023] Open
Abstract
In traditional Chinese medicine (TCM), the liver is the "general organ" that is responsible for governing/maintaining the free flow of qi over the entire body and storing blood. According to the classic five elements theory, zang-xiang theory, yin-yang theory, meridians and collaterals theory, and the five-viscera correlation theory, the liver has essential relationships with many extrahepatic organs or tissues, such as the mother-child relationships between the liver and the heart, and the yin-yang and exterior-interior relationships between the liver and the gallbladder. The influences of the liver to the extrahepatic organs or tissues have been well-established when treating the extrahepatic diseases from the perspective of modulating the liver by using the ancient classic prescriptions of TCM and the acupuncture and moxibustion. In modern medicine, as the largest solid organ in the human body, the liver has the typical functions of filtration and storage of blood; metabolism of carbohydrates, fats, proteins, hormones, and foreign chemicals; formation of bile; storage of vitamins and iron; and formation of coagulation factors. The liver also has essential endocrine function, and acts as an immunological organ due to containing the resident immune cells. In the perspective of modern human anatomy, physiology, and pathophysiology, the liver has the organ interactions with the extrahepatic organs or tissues, for example, the gut, pancreas, adipose, skeletal muscle, heart, lung, kidney, brain, spleen, eyes, skin, bone, and sexual organs, through the circulation (including hemodynamics, redox signals, hepatokines, metabolites, and the translocation of microbiota or its products, such as endotoxins), the neural signals, or other forms of pathogenic factors, under normal or diseases status. The organ interactions centered on the liver not only influence the homeostasis of these indicated organs or tissues, but also contribute to the pathogenesis of cardiometabolic diseases (including obesity, type 2 diabetes mellitus, metabolic [dysfunction]-associated fatty liver diseases, and cardio-cerebrovascular diseases), pulmonary diseases, hyperuricemia and gout, chronic kidney disease, and male and female sexual dysfunction. Therefore, based on TCM and modern medicine, the liver has the bidirectional interaction with the extrahepatic organ or tissue, and this established bidirectional interaction system may further interact with another one or more extrahepatic organs/tissues, thus depicting a complex "pan-hepatic network" model. The pan-hepatic network acts as one of the essential mechanisms of homeostasis and the pathogenesis of diseases.
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Affiliation(s)
- Yaxing Zhang
- Department of Physiology; Research Centre of Basic Integrative Medicine, School of Basic Medical Sciences, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong; Issue 12th of Guangxi Apprenticeship Education of Traditional Chinese Medicine (Shi-Cheng Class of Guangxi University of Chinese Medicine), College of Continuing Education, Guangxi University of Chinese Medicine, Nanning, Guangxi, China
| | - Xian-Ming Fang
- Department of Cardiology, Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine (Guangxi Hospital of Integrated Chinese Medicine and Western Medicine, Ruikang Clinical Faculty of Guangxi University of Chinese Medicine), Guangxi University of Chinese Medicine, Nanning, Guangxi, China
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2
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Druzak SA, Tardelli M, Mays SG, El Bejjani M, Mo X, Maner-Smith KM, Bowen T, Cato ML, Tillman MC, Sugiyama A, Xie Y, Fu H, Cohen DE, Ortlund EA. Ligand dependent interaction between PC-TP and PPARδ mitigates diet-induced hepatic steatosis in male mice. Nat Commun 2023; 14:2748. [PMID: 37173315 PMCID: PMC10182070 DOI: 10.1038/s41467-023-38010-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 04/12/2023] [Indexed: 05/15/2023] Open
Abstract
Phosphatidylcholine transfer protein (PC-TP; synonym StarD2) is a soluble lipid-binding protein that transports phosphatidylcholine (PC) between cellular membranes. To better understand the protective metabolic effects associated with hepatic PC-TP, we generated a hepatocyte-specific PC-TP knockdown (L-Pctp-/-) in male mice, which gains less weight and accumulates less liver fat compared to wild-type mice when challenged with a high-fat diet. Hepatic deletion of PC-TP also reduced adipose tissue mass and decreases levels of triglycerides and phospholipids in skeletal muscle, liver and plasma. Gene expression analysis suggest that the observed metabolic changes are related to transcriptional activity of peroxisome proliferative activating receptor (PPAR) family members. An in-cell protein complementation screen between lipid transfer proteins and PPARs uncovered a direct interaction between PC-TP and PPARδ that was not observed for other PPARs. We confirmed the PC-TP- PPARδ interaction in Huh7 hepatocytes, where it was found to repress PPARδ-mediated transactivation. Mutations of PC-TP residues implicated in PC binding and transfer reduce the PC-TP-PPARδ interaction and relieve PC-TP-mediated PPARδ repression. Reduction of exogenously supplied methionine and choline reduces the interaction while serum starvation enhances the interaction in cultured hepatocytes. Together our data points to a ligand sensitive PC-TP- PPARδ interaction that suppresses PPAR activity.
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Affiliation(s)
- Samuel A Druzak
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Matteo Tardelli
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Suzanne G Mays
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Mireille El Bejjani
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Xulie Mo
- Department of Chemical Biology and Pharmacology, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Kristal M Maner-Smith
- Emory Integrated Lipidomics and Metabolomics Core, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Thomas Bowen
- Emory Integrated Lipidomics and Metabolomics Core, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Michael L Cato
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Matthew C Tillman
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - Akiko Sugiyama
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY, USA
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Yang Xie
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY, USA
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Haian Fu
- Department of Chemical Biology and Pharmacology, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA
| | - David E Cohen
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY, USA
- Division of Gastroenterology, Hepatology and Endoscopy, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Eric A Ortlund
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA, USA.
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3
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Hasan KM, Parveen M, Pena A, Bautista F, Rivera JC, Huerta RR, Martinez E, Espinoza-Derout J, Sinha-Hikim AP, Friedman TC. Fatty Acid Excess Dysregulates CARF to Initiate the Development of Hepatic Steatosis. Cells 2023; 12:1069. [PMID: 37048142 PMCID: PMC10093423 DOI: 10.3390/cells12071069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/22/2023] [Accepted: 03/30/2023] [Indexed: 04/05/2023] Open
Abstract
CARF (CDKN2AIP) regulates cellular fate in response to various stresses. However, its role in metabolic stress is unknown. We found that fatty livers from mice exhibit low CARF expression. Similarly, overloaded palmitate inhibited CARF expression in HepG2 cells, suggesting that excess fat-induced stress downregulates hepatic CARF. In agreement with this, silencing and overexpressing CARF resulted in higher and lower fat accumulation in HepG2 cells, respectively. Furthermore, CARF overexpression lowered the ectopic palmitate accumulation in HepG2 cells. We were interested in understanding the role of hepatic CARF and underlying mechanisms in the development of NAFLD. Mechanistically, transcriptome analysis revealed that endoplasmic reticulum (ER) stress and oxidative stress pathway genes significantly altered in the absence of CARF. IRE1α, GRP78, and CHOP, markers of ER stress, were increased, and the treatment with TUDCA, an ER stress inhibitor, attenuated fat accumulation in CARF-deficient cells. Moreover, silencing CARF caused a reduction of GPX3 and TRXND3, leading to oxidative stress and apoptotic cell death. Intriguingly, CARF overexpression in HFD-fed mice significantly decreased hepatic steatosis. Furthermore, overexpression of CARF ameliorated the aberrant ER function and oxidative stress caused by fat accumulation. Our results further demonstrated that overexpression of CARF alleviates HFD-induced insulin resistance assessed with ITT and GTT assay. Altogether, we conclude that excess fat-induced reduction of CARF dysregulates ER functions and lipid metabolism leading to hepatic steatosis.
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Affiliation(s)
- Kamrul M. Hasan
- Division of Endocrinology, Metabolism and Molecular Medicine, Department of Internal Medicine, Charles R. Drew University, Los Angeles, CA 90059, USA
- David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Meher Parveen
- Division of Endocrinology, Metabolism and Molecular Medicine, Department of Internal Medicine, Charles R. Drew University, Los Angeles, CA 90059, USA
| | - Alondra Pena
- California State University Dominguez Hills, Carson, CA 90747, USA
| | | | - Juan Carlos Rivera
- Division of Endocrinology, Metabolism and Molecular Medicine, Department of Internal Medicine, Charles R. Drew University, Los Angeles, CA 90059, USA
| | - Roxana Ramirez Huerta
- Division of Endocrinology, Metabolism and Molecular Medicine, Department of Internal Medicine, Charles R. Drew University, Los Angeles, CA 90059, USA
| | - Erica Martinez
- Division of Endocrinology, Metabolism and Molecular Medicine, Department of Internal Medicine, Charles R. Drew University, Los Angeles, CA 90059, USA
| | - Jorge Espinoza-Derout
- Division of Endocrinology, Metabolism and Molecular Medicine, Department of Internal Medicine, Charles R. Drew University, Los Angeles, CA 90059, USA
- David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Amiya P. Sinha-Hikim
- Division of Endocrinology, Metabolism and Molecular Medicine, Department of Internal Medicine, Charles R. Drew University, Los Angeles, CA 90059, USA
- David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Theodore C. Friedman
- Division of Endocrinology, Metabolism and Molecular Medicine, Department of Internal Medicine, Charles R. Drew University, Los Angeles, CA 90059, USA
- David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Kong X, Zhu Q, Dong Y, Li Y, Liu J, Yan Q, Huang M, Niu Y. Analysis of serum fatty acid, amino acid, and organic acid profiles in gestational hypertension and gestational diabetes mellitus via targeted metabolomics. Front Nutr 2022; 9:974902. [PMID: 36091252 PMCID: PMC9458889 DOI: 10.3389/fnut.2022.974902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 08/08/2022] [Indexed: 12/04/2022] Open
Abstract
This study aimed to characterize metabolite differences and correlations between hypertensive disorders of pregnancy (HP) and gestational diabetes mellitus (GDM) using univariate, multivariate analyses, RF, and pathway analyses in a cross-sectional study. Dietary surveys were collected and targeted metabolomics was applied to measure levels of serum fatty acids, amino acids, and organic acids in 90 pregnant women at 24–28 weeks gestation at the First Affiliated Hospital of Harbin Medical University. Principal components analysis (PCA) and partial least squares-discriminatory analysis (PLS-DA) models were established to distinguish HP, GDM, and healthy, pregnant control individuals. Univariate and multivariate statistical analyses and Random Forest (RF) were used to identify and map co-metabolites to corresponding pathways in the disease states. Finally, risk factors for the disease were assessed by receiver operating characteristics (ROC) analysis. Dietary survey results showed that HP and GDM patients consumed a high-energy diet and the latter also consumed a high-carbohydrate and high-fat diet. Univariate analysis of clinical indices revealed HP and GDM patients had glycolipid disorders, with the former possessing more severe organ dysfunction. Subsequently, co-areas with significant differences identified by basic discriminant analyses and RF revealed lower levels of pyroglutamic acid and higher levels of 2-hydroxybutyric acid and glutamic acid in the GDM group. The number of metabolites increased in the HP group as compared to the healthy pregnant control group, including pyroglutamic acid, γ-aminobutyric acid (GABA), glutamic acid, oleic acid (C18:1), and palmitic acid (C16:0). ROC curves indicated that area under curve (AUC) for pyroglutamic acid in the GDM group was 0.962 (95% CI, 0.920–1.000), and the AUC of joint indicators, including pyroglutamic acid and GABA, in the HP group was 0.972 (95% CI, 0.938–1.000). Collectively, these results show that both GDM and HP patients at mid-gestation possessed dysregulated glucose and lipid metabolism, which may trigger oxidative stress via glutathione metabolism and biosynthesis of unsaturated fatty acids.
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Affiliation(s)
- Xiangju Kong
- Department of Gynaecology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Qiushuang Zhu
- Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, Harbin, China
| | - Yuanjie Dong
- Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, Harbin, China
| | - Yuqiao Li
- Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, Harbin, China
| | - Jinxiao Liu
- Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, Harbin, China
| | - Qingna Yan
- Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, Harbin, China
| | - Mingli Huang
- Department of Gynaecology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
- Mingli Huang,
| | - Yucun Niu
- Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, Harbin, China
- *Correspondence: Yucun Niu,
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Ferreira I, Machado de Oliveira R, Carvalho AS, Teshima A, Beck HC, Matthiesen R, Costa-Silva B, Macedo MP. Messages from the Small Intestine Carried by Extracellular Vesicles in Prediabetes: A Proteomic Portrait. J Proteome Res 2022; 21:910-920. [PMID: 35263542 PMCID: PMC8982452 DOI: 10.1021/acs.jproteome.1c00353] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Extracellular vesicles (EVs) mediate communication in physiological and pathological conditions. In the pathogenesis of type 2 diabetes, inter-organ communication plays an important role in its progress and metabolic surgery leads to its remission. Moreover, gut dysbiosis is emerging as a diabetogenic factor. However, it remains unclear how the gut senses metabolic alterations and whether this is transmitted to other tissues via EVs. Using a diet-induced prediabetic mouse model, we observed that protein packaging in gut-derived EVs (GDE), specifically the small intestine, is altered in prediabetes. Proteins related to lipid metabolism and to oxidative stress management were more abundant in prediabetic GDE compared to healthy controls. On the other hand, proteins related to glycolytic activity, as well as those responsible for the degradation of polyubiquitinated composites, were depleted in prediabetic GDE. Together, our findings show that protein packaging in GDE is markedly modified during prediabetes pathogenesis, thus suggesting that prediabetic alterations in the small intestine are translated into modified GDE proteomes, which are dispersed into the circulation where they can interact with and influence the metabolic status of other tissues. This study highlights the importance of the small intestine as a tissue that propagates prediabetic metabolic dysfunction throughout the body and the importance of GDE as the messengers. Data are available via ProteomeXchange with identifier PXD028338.
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Affiliation(s)
- Inês Ferreira
- Chronic Diseases Research Centre, CEDOC, NOVA Medical School, (NMS/FCM), Lisbon 1169-056, Portugal.,Bioengineering─Cell Therapies and Regenerative Medicine PhD Program, Instituto Superior Técnico, University of Lisbon, Lisbon 1049-001, Portugal.,Champalimaud Research, Champalimaud Centre for the Unknown, 1400-038 Lisbon, Portugal
| | - Rita Machado de Oliveira
- Chronic Diseases Research Centre, CEDOC, NOVA Medical School, (NMS/FCM), Lisbon 1169-056, Portugal
| | - Ana Sofia Carvalho
- Chronic Diseases Research Centre, CEDOC, NOVA Medical School, (NMS/FCM), Lisbon 1169-056, Portugal
| | - Akiko Teshima
- Chronic Diseases Research Centre, CEDOC, NOVA Medical School, (NMS/FCM), Lisbon 1169-056, Portugal
| | - Hans Christian Beck
- Centre for Clinical Proteomics, Department of Clinical Biochemistry and Pharmacology, Odense University Hospital, Odense 5000, Denmark
| | - Rune Matthiesen
- Chronic Diseases Research Centre, CEDOC, NOVA Medical School, (NMS/FCM), Lisbon 1169-056, Portugal
| | - Bruno Costa-Silva
- Champalimaud Research, Champalimaud Centre for the Unknown, 1400-038 Lisbon, Portugal
| | - Maria Paula Macedo
- Chronic Diseases Research Centre, CEDOC, NOVA Medical School, (NMS/FCM), Lisbon 1169-056, Portugal.,APDP-ERC Portuguese Diabetes Association Education and Research Centre, Lisbon 1250-189, Portugal.,Departament of Medical Sciences, University of Aveiro, Aveiro 3810-193, Portugal
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Imai N, Nicholls HT, Alves-Bezerra M, Li Y, Ivanova AA, Ortlund EA, Cohen DE. Up-regulation of thioesterase superfamily member 2 in skeletal muscle promotes hepatic steatosis and insulin resistance in mice. Hepatology 2022; 75:154-169. [PMID: 34433228 PMCID: PMC9938941 DOI: 10.1002/hep.32122] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/15/2021] [Accepted: 07/26/2021] [Indexed: 01/04/2023]
Abstract
BACKGROUND AND AIMS Thioesterase superfamily member 2 (Them2) is highly expressed in liver and oxidative tissues, where it hydrolyzes long-chain fatty acyl-CoA esters to free fatty acids and CoA. Although mice globally lacking Them2 (Them2-/- ) are protected against diet-induced obesity, hepatic steatosis (HS), and insulin resistance (IR), liver-specific Them2-/- mice remain susceptible. The aim of this study was to test whether Them2 activity in extrahepatic oxidative tissues is a primary determinant of HS and IR. APPROACH AND RESULTS Upon observing IR and up-regulation of Them2 in skeletal, but not cardiac, muscle of high-fat-diet (HFD)-fed wild-type compared to Them2-/- mice, we created mice with Them2 specifically deleted in skeletal (S-Them2-/- ) and cardiac muscle (C-Them2-/- ), as well as in adipose tissue (A-Them2-/- ). When fed an HFD, S-Them2-/- , but not C-Them2-/- or A-Them2-/- , mice exhibited reduced weight gain and improved glucose homeostasis and insulin sensitivity. Reconstitution of Them2 expression in skeletal muscle of global Them2-/- mice, using adeno-associated virus, was sufficient to restore excess weight gain. Increased rates of fatty acid oxidation in skeletal muscle of S-Them2-/- mice contributed to protection from HFD-induced HS by increasing VLDL triglyceride secretion rates in response to greater demand. Increases in insulin sensitivity were further attributable to alterations in production of skeletal muscle metabolites, including short-chain fatty acids, branched-chain amino acids, and pentose phosphate pathway intermediates, as well as in expression of myokines that modulate insulin responsiveness. CONCLUSIONS These results reveal a key role for skeletal muscle Them2 in the pathogenesis of HS and IR and implicate it as a target in the management of NAFLD.
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Affiliation(s)
- Norihiro Imai
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, NY 10021 USA
| | - Hayley T. Nicholls
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, NY 10021 USA
| | - Michele Alves-Bezerra
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, NY 10021 USA
| | - Yingxia Li
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, NY 10021 USA
| | - Anna A. Ivanova
- Department of Biochemistry, Emory University, Atlanta, GA 30322 USA
| | - Eric A. Ortlund
- Department of Biochemistry, Emory University, Atlanta, GA 30322 USA
| | - David E. Cohen
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, NY 10021 USA
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Heeren J, Scheja L. Metabolic-associated fatty liver disease and lipoprotein metabolism. Mol Metab 2021; 50:101238. [PMID: 33892169 PMCID: PMC8324684 DOI: 10.1016/j.molmet.2021.101238] [Citation(s) in RCA: 223] [Impact Index Per Article: 74.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/01/2021] [Accepted: 04/15/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Non-alcoholic fatty liver disease, or as recently proposed 'metabolic-associated fatty liver disease' (MAFLD), is characterized by pathological accumulation of triglycerides and other lipids in hepatocytes. This common disease can progress from simple steatosis to steatohepatitis, and eventually end-stage liver diseases. MAFLD is closely related to disturbances in systemic energy metabolism, including insulin resistance and atherogenic dyslipidemia. SCOPE OF REVIEW The liver is the central organ in lipid metabolism by secreting very low density lipoproteins (VLDL) and, on the other hand, by internalizing fatty acids and lipoproteins. This review article discusses recent research addressing hepatic lipid synthesis, VLDL production, and lipoprotein internalization as well as the lipid exchange between adipose tissue and the liver in the context of MAFLD. MAJOR CONCLUSIONS Liver steatosis in MAFLD is triggered by excessive hepatic triglyceride synthesis utilizing fatty acids derived from white adipose tissue (WAT), de novo lipogenesis (DNL) and endocytosed remnants of triglyceride-rich lipoproteins. In consequence of high hepatic lipid content, VLDL secretion is enhanced, which is the primary cause of complex dyslipidemia typical for subjects with MAFLD. Interventions reducing VLDL secretory capacity attenuate dyslipidemia while they exacerbate MAFLD, indicating that the balance of lipid storage versus secretion in hepatocytes is a critical parameter determining disease outcome. Proof of concept studies have shown that promoting lipid storage and energy combustion in adipose tissues reduces hepatic lipid load and thus ameliorates MAFLD. Moreover, hepatocellular triglyceride synthesis from DNL and WAT-derived fatty acids can be targeted to treat MAFLD. However, more research is needed to understand how individual transporters, enzymes, and their isoforms affect steatosis and dyslipidemia in vivo, and whether these two aspects of MAFLD can be selectively treated. Processing of cholesterol-enriched lipoproteins appears less important for steatosis. It may, however, modulate inflammation and consequently MAFLD progression.
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Affiliation(s)
- Joerg Heeren
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Ludger Scheja
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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Thioesterase superfamily member 1 undergoes stimulus-coupled conformational reorganization to regulate metabolism in mice. Nat Commun 2021; 12:3493. [PMID: 34108467 PMCID: PMC8190112 DOI: 10.1038/s41467-021-23595-x] [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] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 04/29/2021] [Indexed: 01/21/2023] Open
Abstract
In brown adipose tissue, thermogenesis is suppressed by thioesterase superfamily member 1 (Them1), a long chain fatty acyl-CoA thioesterase. Them1 is highly upregulated by cold ambient temperature, where it reduces fatty acid availability and limits thermogenesis. Here, we show that Them1 regulates metabolism by undergoing conformational changes in response to β-adrenergic stimulation that alter Them1 intracellular distribution. Them1 forms metabolically active puncta near lipid droplets and mitochondria. Upon stimulation, Them1 is phosphorylated at the N-terminus, inhibiting puncta formation and activity and resulting in a diffuse intracellular localization. We show by correlative light and electron microscopy that Them1 puncta are biomolecular condensates that are inhibited by phosphorylation. Thus, Them1 forms intracellular biomolecular condensates that limit fatty acid oxidation and suppress thermogenesis. During a period of energy demand, the condensates are disrupted by phosphorylation to allow for maximal thermogenesis. The stimulus-coupled reorganization of Them1 provides fine-tuning of thermogenesis and energy expenditure.
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9
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Jiang X, Ding WX. Acyl Coenzyme A Thioesterase 9: A Novel Target for Nonalcoholic Fatty Liver Disease by Shuttling Mitochondrial Short-Chain Fatty Acids? Hepatology 2020; 72:797-800. [PMID: 32614087 PMCID: PMC7722112 DOI: 10.1002/hep.31450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 06/23/2020] [Accepted: 06/25/2020] [Indexed: 12/07/2022]
Affiliation(s)
- Xiaoxiao Jiang
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS
| | - Wen-Xing Ding
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS
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10
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Steensels S, Qiao J, Zhang Y, Maner-Smith KM, Kika N, Holman CD, Corey KE, Bracken WC, Ortlund EA, Ersoy BA. Acyl-Coenzyme A Thioesterase 9 Traffics Mitochondrial Short-Chain Fatty Acids Toward De Novo Lipogenesis and Glucose Production in the Liver. Hepatology 2020; 72:857-872. [PMID: 32498134 DOI: 10.1002/hep.31409] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 05/07/2020] [Accepted: 05/16/2020] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND AIMS Obesity-induced pathogenesis of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) is associated with increased de novo lipogenesis (DNL) and hepatic glucose production (HGP) that is due to excess fatty acids. Acyl-coenzyme A (CoA) thioesterase (Acot) family members control the cellular utilization of fatty acids by hydrolyzing (deactivating) acyl-CoA into nonesterified fatty acids and CoASH. APPROACH AND RESULTS Using Caenorhabditis elegans, we identified Acot9 as the strongest regulator of lipid accumulation within the Acot family. Indicative of a maladaptive function, hepatic Acot9 expression was higher in patients with obesity who had NAFLD and NASH compared with healthy controls with obesity. In the setting of excessive nutrition, global ablation of Acot9 protected mice against increases in weight gain, HGP, steatosis, and steatohepatitis. Supportive of a hepatic function, the liver-specific deletion of Acot9 inhibited HGP and steatosis in mice without affecting diet-induced weight gain. By contrast, the rescue of Acot9 expression only in the livers of Acot9 knockout mice was sufficient to promote HGP and steatosis. Mechanistically, hepatic Acot9 localized to the inner mitochondrial membrane, where it deactivated short-chain but not long-chain fatty acyl-CoA. This unique localization and activity of Acot9 directed acetyl-CoA away from protein lysine acetylation and toward the citric acid (TCA) cycle. Acot9-mediated exacerbation of triglyceride and glucose biosynthesis was attributable at least in part to increased TCA cycle activity, which provided substrates for HGP and DNL. β-oxidation and ketone body production, which depend on long-chain fatty acyl-CoA, were not regulated by Acot9. CONCLUSIONS Taken together, our findings indicate that Acot9 channels hepatic acyl-CoAs toward increased HGP and DNL under the pathophysiology of obesity. Therefore, Acot9 represents a target for the management of NAFLD.
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Affiliation(s)
- Sandra Steensels
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY
| | - Jixuan Qiao
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY
| | - Yanzhen Zhang
- Department of Gastroenterology, First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | | | - Nourhan Kika
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY
| | - Corey D Holman
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY
| | - Kathleen E Corey
- Gastrointestinal Unit, Massachusetts General Hospital, Boston, MA
| | - W Clay Bracken
- Department of Biochemistry, Weill Cornell Medical College, New York, NY
| | - Eric A Ortlund
- Emory Integrated Lipidomics Core, Emory University, Atlanta, GA
| | - Baran A Ersoy
- Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY
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The Vitamin D Receptor Regulates Glycerolipid and Phospholipid Metabolism in Human Hepatocytes. Biomolecules 2020; 10:biom10030493. [PMID: 32213983 PMCID: PMC7175212 DOI: 10.3390/biom10030493] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 03/18/2020] [Accepted: 03/20/2020] [Indexed: 12/13/2022] Open
Abstract
The vitamin D receptor (VDR) must be relevant to liver lipid metabolism because VDR deficient mice are protected from hepatosteatosis. Therefore, our objective was to define the role of VDR on the overall lipid metabolism in human hepatocytes. We developed an adenoviral vector for human VDR and performed transcriptomic and metabolomic analyses of cultured human hepatocytes upon VDR activation by vitamin D (VitD). Twenty percent of the VDR responsive genes were related to lipid metabolism, including MOGAT1, LPGAT1, AGPAT2, and DGAT1 (glycerolipid metabolism); CDS1, PCTP, and MAT1A (phospholipid metabolism); and FATP2, SLC6A12, and AQP3 (uptake of fatty acids, betaine, and glycerol, respectively). They were rapidly induced (4–6 h) upon VDR activation by 10 nM VitD or 100 µM lithocholic acid (LCA). Most of these genes were also upregulated by VDR/VitD in mouse livers in vivo. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS) metabolomics demonstrated intracellular accumulation of triglycerides, with concomitant decreases in diglycerides and phosphatidates, at 8 and 24 h upon VDR activation. Significant alterations in phosphatidylcholines, increases in lyso-phosphatidylcholines and decreases in phosphatidylethanolamines and phosphatidylethanolamine plasmalogens were also observed. In conclusion, active VitD/VDR signaling in hepatocytes triggers an unanticipated coordinated gene response leading to triglyceride synthesis and to important perturbations in glycerolipids and phospholipids.
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Krisko TI, Nicholls HT, Bare CJ, Holman CD, Putzel GG, Jansen RS, Sun N, Rhee KY, Banks AS, Cohen DE. Dissociation of Adaptive Thermogenesis from Glucose Homeostasis in Microbiome-Deficient Mice. Cell Metab 2020; 31:592-604.e9. [PMID: 32084379 PMCID: PMC7888548 DOI: 10.1016/j.cmet.2020.01.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 11/18/2019] [Accepted: 01/24/2020] [Indexed: 01/16/2023]
Abstract
Recent studies suggest that a key mechanism whereby the gut microbiome influences energy balance and glucose homeostasis is through the recruitment of brown and beige adipocytes, primary mediators of the adaptive thermogenic response. To test this, we assessed energy expenditure and glucose metabolism in two complementary mouse models of gut microbial deficiency, which were exposed to a broad range of thermal and dietary stresses. Neither ablation of the gut microbiome, nor the substantial microbial perturbations induced by cold ambient temperatures, influenced energy expenditure during cold exposure or high-fat feeding. Nevertheless, we demonstrated a critical role for gut microbial metabolism in maintaining euglycemia through the production of amino acid metabolites that optimized hepatic TCA (tricarboxylic acid) cycle fluxes in support of gluconeogenesis. These results distinguish the dispensability of the gut microbiome for the regulation of energy expenditure from its critical contribution to the maintenance of glucose homeostasis.
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Affiliation(s)
- Tibor I Krisko
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA
| | - Hayley T Nicholls
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA
| | - Curtis J Bare
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA
| | - Corey D Holman
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA
| | - Gregory G Putzel
- Jill Roberts Institute for Research in Inflammatory Bowel Disease, Weill Cornell Medical College, New York, NY 10021, USA
| | - Robert S Jansen
- Division of Infectious Diseases, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA
| | - Natalie Sun
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA
| | - Kyu Y Rhee
- Division of Infectious Diseases, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA
| | - Alexander S Banks
- Division of Endocrinology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - David E Cohen
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY 10021, USA.
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