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Aldworth H, Hooper NM. Post-translational regulation of the low-density lipoprotein receptor provides new targets for cholesterol regulation. Biochem Soc Trans 2024; 52:431-440. [PMID: 38329179 PMCID: PMC10903450 DOI: 10.1042/bst20230918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 02/09/2024]
Abstract
The amount of the low-density lipoprotein receptor (LDLR) on the surface of hepatocytes is the primary determinant of plasma low-density lipoprotein (LDL)-cholesterol level. Although the synthesis and cellular trafficking of the LDLR have been well-documented, there is growing evidence of additional post-translational mechanisms that regulate or fine tune the surface availability of the LDLR, thus modulating its ability to bind and internalise LDL-cholesterol. Proprotein convertase subtilisin/kexin type 9 and the asialoglycoprotein receptor 1 both independently interact with the LDLR and direct it towards the lysosome for degradation. While ubiquitination by the E3 ligase inducible degrader of the LDLR also targets the receptor for lysosomal degradation, ubiquitination of the LDLR by a different E3 ligase, RNF130, redistributes the receptor away from the plasma membrane. The activity of the LDLR is also regulated by proteolysis. Proteolytic cleavage of the transmembrane region of the LDLR by γ-secretase destabilises the receptor, directing it to the lysosome for degradation. Shedding of the extracellular domain of the receptor by membrane-type 1 matrix metalloprotease and cleavage of the receptor in its LDL-binding domain by bone morphogenetic protein-1 reduces the ability of the LDLR to bind and internalise LDL-cholesterol at the cell surface. A better understanding of how the activity of the LDLR is regulated will not only unravel the complex biological mechanisms controlling LDL-cholesterol metabolism but also could help inform the development of alternative pharmacological intervention strategies for the treatment of hypercholesterolaemia.
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Affiliation(s)
- Harry Aldworth
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, U.K
| | - Nigel M Hooper
- Division of Neuroscience, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, U.K
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2
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Oh AR, Jeong Y, Yu J, Minh Tam DT, Kang JK, Jung YH, Im SS, Lee SB, Ryu D, Pajvani UB, Kim K. Hepatocyte Kctd17 Inhibition Ameliorates Glucose Intolerance and Hepatic Steatosis Caused by Obesity-induced Chrebp Stabilization. Gastroenterology 2023; 164:439-453. [PMID: 36402191 PMCID: PMC9975067 DOI: 10.1053/j.gastro.2022.11.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 10/13/2022] [Accepted: 11/09/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND & AIMS Obesity predisposes to type 2 diabetes (T2D) and nonalcoholic fatty liver disease (NAFLD), but underlying mechanisms are incompletely understood. Potassium channel tetramerization domain-containing protein 17 (Kctd17) levels are increased in livers from obese mice and humans. In this study, we investigated the mechanism of increased Kctd17 and whether it is causal to obesity-induced metabolic complications. METHODS We transduced Rosa26-LSL-Cas9 knockin mice with AAV8-TBG-Cre (Control), AAV8-U6-Kctd17 sgRNA-TBG-Cre (L-Kctd17), AAV8-U6-Oga sgRNA-TBG-Cre (L-Oga), or AAV8-U6-Kctd17/Oga sgRNA-TBG-Cre (DKO). We fed mice a high-fat diet (HFD) and assessed for hepatic glucose and lipid homeostasis. We generated Kctd17, O-GlcNAcase (Oga), or Kctd17/Oga-knockout hepatoma cells by CRISPR-Cas9, and Kctd17-directed antisense oligonucleotide to test therapeutic potential in vivo. We analyzed transcriptomic data from patients with NAFLD. RESULTS Hepatocyte Kctd17 expression was increased in HFD-fed mice due to increased Srebp1c activity. HFD-fed L-Kctd17 or Kctd17 antisense oligonucleotide-treated mice show improved glucose tolerance and hepatic steatosis, whereas forced Kctd17 expression caused glucose intolerance and hepatic steatosis even in lean mice. Kctd17 induced Oga degradation, resulting in increasing carbohydrate response element-binding protein (Chrebp) protein, so concomitant Oga knockout negated metabolic benefits of hepatocyte Kctd17 deletion. In patients with NAFLD, KCTD17 messenger RNA was positively correlated with expression of Chrebp target and other lipogenic genes. CONCLUSIONS Srebp1c-induced hepatocyte Kctd17 expression in obesity disrupted glucose and lipid metabolism by stabilizing Chrebp, and may represent a novel therapeutic target for obesity-induced T2D and NAFLD.
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Affiliation(s)
- Ah-Reum Oh
- Department of Biological Sciences, College of Medicine, Inha University, Incheon, Republic of Korea; Program in Biomedical Science and Engineering, Inha University, Incheon, Republic of Korea; Research Center for Controlling Intercellular Communication (RCIC), College of Medicine, Inha University, Incheon, Republic of Korea
| | - Yelin Jeong
- Department of Biological Sciences, College of Medicine, Inha University, Incheon, Republic of Korea; Program in Biomedical Science and Engineering, Inha University, Incheon, Republic of Korea; Research Center for Controlling Intercellular Communication (RCIC), College of Medicine, Inha University, Incheon, Republic of Korea
| | - Junjie Yu
- Department of Medicine, Columbia University, New York, New York
| | - Dao Thi Minh Tam
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Jin Ku Kang
- Department of Medicine, Columbia University, New York, New York
| | - Young Hoon Jung
- Department of Biological Sciences, College of Medicine, Inha University, Incheon, Republic of Korea; Program in Biomedical Science and Engineering, Inha University, Incheon, Republic of Korea; Research Center for Controlling Intercellular Communication (RCIC), College of Medicine, Inha University, Incheon, Republic of Korea
| | - Seung-Soon Im
- Department of Physiology, Keimyung University School of Medicine, Daegu, Republic of Korea
| | - Sang Bae Lee
- Division of Life Sciences, Jeonbuk National University, Jeonju, Republic of Korea
| | - Dongryeol Ryu
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Utpal B Pajvani
- Department of Medicine, Columbia University, New York, New York.
| | - KyeongJin Kim
- Department of Biological Sciences, College of Medicine, Inha University, Incheon, Republic of Korea; Program in Biomedical Science and Engineering, Inha University, Incheon, Republic of Korea; Research Center for Controlling Intercellular Communication (RCIC), College of Medicine, Inha University, Incheon, Republic of Korea.
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3
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Lu K, Fan Q, Zou X. Antisense oligonucleotide is a promising intervention for liver diseases. Front Pharmacol 2022; 13:1061842. [PMID: 36569303 PMCID: PMC9780395 DOI: 10.3389/fphar.2022.1061842] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 11/28/2022] [Indexed: 12/13/2022] Open
Abstract
As the body's critical metabolic organ, the liver plays an essential role in maintaining proper body homeostasis. However, as people's living standards have improved and the number of unhealthy lifestyles has increased, the liver has become overburdened. These have made liver disease one of the leading causes of death worldwide. Under the influence of adverse factors, liver disease progresses from simple steatosis to hepatitis, to liver fibrosis, and finally to cirrhosis and cancer, followed by increased mortality. Until now, there has been a lack of accepted effective treatments for liver disease. Based on current research, antisense oligonucleotide (ASO), as an alternative intervention for liver diseases, is expected to be an effective treatment due to its high efficiency, low toxicity, low dosage, strong specificity, and additional positive characteristics. In this review, we will first introduce the design, modification, delivery, and the mechanisms of ASO, and then summarize the application of ASO in liver disease treatment, including in non-alcoholic fatty liver disease (NAFLD), hepatitis, liver fibrosis, and liver cancer. Finally, we discuss challenges and perspectives on the transfer of ASO drugs into clinical use. This review provides a current and comprehensive understanding of the integrative and systematic functions of ASO for its use in liver disease.
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Affiliation(s)
- Kailing Lu
- College of Chinese Materia Medica and Yunnan Key Laboratory of Southern Medicinal Utilization, Yunnan University of Chinese Medicine, Kunming, Yunnan, China
| | - Qijing Fan
- Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, Yunnan, China
| | - Xiaoju Zou
- College of Chinese Materia Medica and Yunnan Key Laboratory of Southern Medicinal Utilization, Yunnan University of Chinese Medicine, Kunming, Yunnan, China,*Correspondence: Xiaoju Zou,
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4
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Fang ZQ, Ruan B, Liu JJ, Duan JL, Yue ZS, Song P, Xu H, Ding J, Xu C, Dou GR, Wang L. Notch-triggered maladaptation of liver sinusoidal endothelium aggravates nonalcoholic steatohepatitis through endothelial nitric oxide synthase. Hepatology 2022; 76:742-758. [PMID: 35006626 DOI: 10.1002/hep.32332] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 01/06/2022] [Accepted: 01/06/2022] [Indexed: 01/04/2023]
Abstract
BACKGROUND AND AIMS Although NASH can lead to severe clinical consequences, including cirrhosis and hepatocellular carcinoma, no effective treatment is currently available for this disease. Increasing evidence indicates that LSECs play a critical role in NASH pathogenesis; however, the mechanisms involved in LSEC-mediated NASH remain to be fully elucidated. APPROACH AND RESULTS In the current study, we found that LSEC homeostasis was disrupted and LSEC-specific gene profiles were altered in methionine-choline-deficient (MCD) diet-induced NASH mouse models. Importantly, Notch signaling was found to be activated in LSECs of NASH mice. To then investigate the role of endothelial Notch in NASH progression, we generated mouse lines with endothelial-specific Notch intracellular domain (NICD) overexpression or RBP-J knockout to respectively activate or inhibit Notch signaling in endothelial cells. Notably, endothelial-specific overexpression of the NICD accelerated LSEC maladaptation and aggravated NASH, whereas endothelial cell-specific inhibition of Notch signaling restored LSEC homeostasis and improved NASH phenotypes. Furthermore, we demonstrated that endothelial-specific Notch activation exacerbated NASH by inhibiting endothelial nitric oxide synthase (eNOS) transcription, whereas administration of the pharmacological eNOS activator YC-1 alleviated hepatic steatosis and lipid accumulation resulting from Notch activation. Finally, to explore the therapeutic potential of using Notch inhibitors in NASH treatment, we applied two gamma-secretase inhibitors-DAPT and LY3039478-in an MCD diet-induced mouse model of NASH, and found that both inhibitors effectively ameliorated hepatic steatosis, inflammation, and liver fibrosis. CONCLUSIONS Endothelial-specific Notch activation triggered LSEC maladaptation and exacerbated NASH phenotypes in an eNOS-dependent manner. Genetic and pharmacological inhibition of Notch signaling effectively restored LSEC homeostasis and ameliorated NASH progression.
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Affiliation(s)
- Zhi-Qiang Fang
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China
| | - Bai Ruan
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi'an, China.,Center of Clinical Aerospace Medicine & Department of Aviation Medicine, Fourth Military Medical University, Xi'an, China
| | - Jing-Jing Liu
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China
| | - Juan-Li Duan
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China
| | - Zhen-Sheng Yue
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China.,Department of Ophthalmology, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China
| | - Ping Song
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China
| | - Hao Xu
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China
| | - Jian Ding
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China
| | - Chen Xu
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China
| | - Guo-Rui Dou
- Department of Ophthalmology, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China
| | - Lin Wang
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China.,State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi'an, China
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Gu J, Geng M, Qi M, Wang L, Zhang Y, Gao J. The role of lysosomal membrane proteins in glucose and lipid metabolism. FASEB J 2021; 35:e21848. [PMID: 34582051 DOI: 10.1096/fj.202002602r] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 07/11/2021] [Accepted: 07/26/2021] [Indexed: 11/11/2022]
Abstract
Lysosomes have long been regarded as the "garbage dump" of the cell. More recently, however, researchers have revealed novel roles for lysosomal membranes in autophagy, ion transport, nutrition sensing, and membrane fusion and repair. With active research into lysosomal membrane proteins (LMP), increasing evidence has become available showing that LMPs are inextricably linked to glucose and lipid metabolism, and this relationship represents mutual influence and regulation. In this review, we summarize the roles of LMPs in relation to glucose and lipid metabolism, and describe their roles in glucose transport, glycolysis, cholesterol transport, and lipophagy. The role of transport proteins can be traced back to the original discoveries of GLUT8, NPC1, and NPC2, which were all found to have significant roles in the pathways involved in glucose and lipid metabolism. CLC-5 and SIDT2-knockout animals show serious phenotypic disorders of metabolism, and V-ATPase and LAMP-2 have been found to interact with proteins related to glucose and lipid metabolism. These findings all emphasize the critical role of LMPs in glycolipid metabolism and help to strengthen our understanding of the independent and close relationship between LMPs and glycolipid metabolism.
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Affiliation(s)
- Jing Gu
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
| | - Mengya Geng
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- School of Clinical Medicine, Wannan Medical College, Wuhu, China
| | - Mengxiang Qi
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- School of Clinical Medicine, Wannan Medical College, Wuhu, China
| | - Lizhuo Wang
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- Department of Biochemistry and Molecular Biology, Wannan Medical College, Wuhu, China
| | - Yao Zhang
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
- Department of Biochemistry and Molecular Biology, Wannan Medical College, Wuhu, China
| | - Jialin Gao
- Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Institute of Endocrine and Metabolic Diseases, Department of Endocrinology and Genetic Metabolism, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, China
- Anhui Province Key Laboratory of Biological Macro-Molecules Research (Wannan Medical College), Wannan Medical College, Wuhu, China
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Oikawa N, Fabiano M, Müller UC, Walter J. Carboxy-terminal fragment of amyloid precursor protein mediates lipid droplet accumulation upon γ-secretase inhibition. Biochem Biophys Res Commun 2021; 570:137-142. [PMID: 34280617 DOI: 10.1016/j.bbrc.2021.07.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 07/07/2021] [Indexed: 11/20/2022]
Abstract
γ-Secretase is a protease catalysing the proteolysis of type-I membrane proteins usually after precedent ectodomain shedding of the respective protein substrates. Since proteolysis of membrane proteins is involved in fundamental cellular signaling pathways, dysfunction of γ-secretase can have significant impact on cellular metabolism and differentiation. Here, we examined the role of γ-secretase in cellular lipid metabolism using neuronally differentiated human SH-SY5Y cells. The pharmacological inhibition of γ-secretase induced lipid droplet (LD) accumulation. The LD accumulation was significantly attenuated by preventing the accumulation of C-terminal fragment of the amyloid precursor protein (APP-CTF), which is a direct substrate of γ-secretase. Additionally, LD accumulation upon γ-secretase inhibition was not induced in APP-knock out (APP-KO) mouse embryonic fibroblasts (MEFs), suggesting significant involvement of APP-CTF accumulation in LD accumulation upon γ-secretase inhibition. On the other hand, γ-secretase inhibition-dependent cholesterol accumulation was not attenuated by inhibition of APP-CTF accumulation in the differentiated SH-SY5Y cells nor in APP-KO MEFs. These results suggest that γ-secretase inhibition can induce accumulation of LD and cholesterol differentially via APP-CTF accumulation.
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Affiliation(s)
- Naoto Oikawa
- Department of Neurology, University Hospital Bonn, 53127, Bonn, Germany.
| | - Marietta Fabiano
- Department of Neurology, University Hospital Bonn, 53127, Bonn, Germany
| | - Ulrike C Müller
- Institute for Pharmacy and Molecular Biotechnology, University of Heidelberg, 69120, Heidelberg, Germany
| | - Jochen Walter
- Department of Neurology, University Hospital Bonn, 53127, Bonn, Germany.
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7
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Rimbert A, Dalila N, Wolters JC, Huijkman N, Smit M, Kloosterhuis N, Riemsma M, van der Veen Y, Singla A, van Dijk F, Frikke-Schmidt R, Burstein E, Tybjærg-Hansen A, van de Sluis B, Kuivenhoven JA. A common variant in CCDC93 protects against myocardial infarction and cardiovascular mortality by regulating endosomal trafficking of low-density lipoprotein receptor. Eur Heart J 2021; 41:1040-1053. [PMID: 31630160 DOI: 10.1093/eurheartj/ehz727] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 02/18/2019] [Accepted: 10/02/2019] [Indexed: 12/24/2022] Open
Abstract
AIMS Genome-wide association studies have previously identified INSIG2 as a candidate gene for plasma low-density lipoprotein cholesterol (LDL-c). However, we suspect a role for CCDC93 in the same locus because of its involvement in the recycling of the LDL-receptor (LDLR). METHODS AND RESULTS Characterization of the INSIG2 locus was followed by studies in over 107 000 individuals from the general population, the Copenhagen General Population Study and the Copenhagen City Heart Study, for associations of genetic variants with plasma lipids levels, with risk of myocardial infarction (MI) and with cardiovascular mortality. CCDC93 was furthermore studied in cells and mice. The lead variant of the INSIG2 locus (rs10490626) is not associated with changes in the expression of nearby genes but is a part of a genetic block, which excludes INSIG2. This block includes a coding variant in CCDC93 p.Pro228Leu, which is in strong linkage disequilibrium with rs10490626 (r2 > 0.96). In the general population, separately and combined, CCDC93 p.Pro228Leu is dose-dependently associated with lower LDL-c (P-trend 2.5 × 10-6 to 8.0 × 10-9), with lower risk of MI (P-trend 0.04-0.002) and lower risk of cardiovascular mortality (P-trend 0.005-0.004). These results were validated for LDL-c, risk of both coronary artery disease and MI in meta-analyses including from 194 000 to >700 000 participants. The variant is shown to increase CCDC93 protein stability, while overexpression of human CCDC93 decreases plasma LDL-c in mice. Conversely, CCDC93 ablation reduces LDL uptake as a result of reduced LDLR levels at the cell membrane. CONCLUSION This study provides evidence that a common variant in CCDC93, encoding a protein involved in recycling of the LDLR, is associated with lower LDL-c levels, lower risk of MI and cardiovascular mortality.
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Affiliation(s)
- Antoine Rimbert
- Section Molecular Genetics, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Building 3226, Rm 04.14, Internal Zip Code EA12, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Nawar Dalila
- Section for Molecular Genetics, Department of Clinical Biochemistry, Rigshospitalet, Copenhagen University Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark
| | - Justina C Wolters
- Section Molecular Genetics, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Building 3226, Rm 04.14, Internal Zip Code EA12, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Nicolette Huijkman
- Section Molecular Genetics, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Building 3226, Rm 04.14, Internal Zip Code EA12, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Marieke Smit
- Section Molecular Genetics, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Building 3226, Rm 04.14, Internal Zip Code EA12, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Niels Kloosterhuis
- Section Molecular Genetics, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Building 3226, Rm 04.14, Internal Zip Code EA12, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Marijn Riemsma
- Section Molecular Genetics, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Building 3226, Rm 04.14, Internal Zip Code EA12, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Ydwine van der Veen
- Section Molecular Genetics, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Building 3226, Rm 04.14, Internal Zip Code EA12, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Amika Singla
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Freerk van Dijk
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | | | - Ruth Frikke-Schmidt
- Section for Molecular Genetics, Department of Clinical Biochemistry, Rigshospitalet, Copenhagen University Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark.,Department of Clinical Biochemistry, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark
| | - Ezra Burstein
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.,Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Anne Tybjærg-Hansen
- Section for Molecular Genetics, Department of Clinical Biochemistry, Rigshospitalet, Copenhagen University Hospital, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark.,Department of Clinical Biochemistry, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark.,The Copenhagen General Population Study, Herlev and Gentofte Hospital, Herlev Ringvej 75, DK-2730 Herlev, Denmark.,The Copenhagen City Heart Study, Bispebjerg and Frederiksberg Hospital, Nordre Fasanvej 57, DK-2000 Frederiksberg, Denmark
| | - Bart van de Sluis
- Section Molecular Genetics, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Building 3226, Rm 04.14, Internal Zip Code EA12, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
| | - Jan Albert Kuivenhoven
- Section Molecular Genetics, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Building 3226, Rm 04.14, Internal Zip Code EA12, Antonius Deusinglaan 1, 9713 AV Groningen, the Netherlands
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8
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Kim K, Kang JK, Jung YH, Lee SB, Rametta R, Dongiovanni P, Valenti L, Pajvani UB. Adipocyte PHLPP2 inhibition prevents obesity-induced fatty liver. Nat Commun 2021; 12:1822. [PMID: 33758172 PMCID: PMC7988046 DOI: 10.1038/s41467-021-22106-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/25/2021] [Indexed: 01/22/2023] Open
Abstract
Increased adiposity confers risk for systemic insulin resistance and type 2 diabetes (T2D), but mechanisms underlying this pathogenic inter-organ crosstalk are incompletely understood. We find PHLPP2 (PH domain and leucine rich repeat protein phosphatase 2), recently identified as the Akt Ser473 phosphatase, to be increased in adipocytes from obese mice. To identify the functional consequence of increased adipocyte PHLPP2 in obese mice, we generated adipocyte-specific PHLPP2 knockout (A-PHLPP2) mice. A-PHLPP2 mice show normal adiposity and glucose metabolism when fed a normal chow diet, but reduced adiposity and improved whole-body glucose tolerance as compared to Cre- controls with high-fat diet (HFD) feeding. Notably, HFD-fed A-PHLPP2 mice show increased HSL phosphorylation, leading to increased lipolysis in vitro and in vivo. Mobilized adipocyte fatty acids are oxidized, leading to increased peroxisome proliferator-activated receptor alpha (PPARα)-dependent adiponectin secretion, which in turn increases hepatic fatty acid oxidation to ameliorate obesity-induced fatty liver. Consistently, adipose PHLPP2 expression is negatively correlated with serum adiponectin levels in obese humans. Overall, these data implicate an adipocyte PHLPP2-HSL-PPARα signaling axis to regulate systemic glucose and lipid homeostasis, and suggest that excess adipocyte PHLPP2 explains decreased adiponectin secretion and downstream metabolic consequence in obesity. Obesity can be associated with an increased risk of metabolic complications. Here, the authors show that adipocyte-specific ablation of the phosphatase PHLPP2 improves glucose homeostasis in high-fat diet fed obese mice, and that this may be due at least in part to PHLPP2 dephosphorylation of HSL.
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Affiliation(s)
- KyeongJin Kim
- Department of Medicine, Columbia University, New York, NY, USA. .,Department of Biomedical Sciences, College of Medicine, Inha University, Incheon, South Korea. .,Department of Biomedical Science, Program in Biomedical Science and Engineering, Inha University, Incheon, Republic of Korea.
| | - Jin Ku Kang
- Department of Medicine, Columbia University, New York, NY, USA
| | - Young Hoon Jung
- Department of Biomedical Sciences, College of Medicine, Inha University, Incheon, South Korea.,Department of Biomedical Science, Program in Biomedical Science and Engineering, Inha University, Incheon, Republic of Korea
| | - Sang Bae Lee
- Division of Life Sciences, Jeonbuk National University, Jeonju, Republic of Korea
| | - Raffaela Rametta
- Internal Medicine and Metabolic Diseases, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, DEPT, Università degli Studi di Milano, Milano, Italy
| | - Paola Dongiovanni
- Internal Medicine and Metabolic Diseases, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, DEPT, Università degli Studi di Milano, Milano, Italy
| | - Luca Valenti
- Internal Medicine and Metabolic Diseases, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, DEPT, Università degli Studi di Milano, Milano, Italy
| | - Utpal B Pajvani
- Department of Medicine, Columbia University, New York, NY, USA.
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9
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Guo Y, Wang Q, Chen S, Xu C. Functions of amyloid precursor protein in metabolic diseases. Metabolism 2021; 115:154454. [PMID: 33248065 DOI: 10.1016/j.metabol.2020.154454] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 11/02/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023]
Abstract
Amyloid precursor protein (APP) is a transmembrane precursor protein that is widely expressed in the central nervous system and peripheral tissues in the liver and pancreas, adipose tissue, and myotubes. APP can be cleaved by proteases in two different ways to produce a variety of short peptides, each with different physiological properties and functions. APP peptides generated by non-amyloidogenic processing can positively influence metabolism, while the peptides produced by amyloidogenic processing have the opposite effects. Here, we summarize the regulatory effects of APP and its cleavage peptides on metabolism in the central nervous system and peripheral tissues. In addition, abnormal expression and function of APP and APP-derived peptides are associated with metabolic diseases, such as type 2 diabetes, obesity, non-alcoholic fatty liver disease, and cardiovascular disease, and cancers. Pharmacological intervention of APP function or reduction of the production of peptides derived from amyloidogenic processing may be effective strategies for the prevention and treatment of Alzheimer's disease, and they may also provide new guidance for the treatment of metabolic diseases.
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Affiliation(s)
- Yanjun Guo
- Department of Gastroenterology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Qinqiu Wang
- Department of Gastroenterology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Shenghui Chen
- Department of Gastroenterology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Chengfu Xu
- Department of Gastroenterology, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China.
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10
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Maladaptive regeneration - the reawakening of developmental pathways in NASH and fibrosis. Nat Rev Gastroenterol Hepatol 2021; 18:131-142. [PMID: 33051603 PMCID: PMC7854502 DOI: 10.1038/s41575-020-00365-6] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/28/2020] [Indexed: 02/06/2023]
Abstract
With the rapid expansion of the obesity epidemic, nonalcoholic fatty liver disease is now the most common chronic liver disease, with almost 25% global prevalence. Nonalcoholic fatty liver disease ranges in severity from simple steatosis, a benign 'pre-disease' state, to the liver injury and inflammation that characterize nonalcoholic steatohepatitis (NASH), which in turn predisposes individuals to liver fibrosis. Fibrosis is the major determinant of clinical outcomes in patients with NASH and is associated with increased risks of cirrhosis and hepatocellular carcinoma. NASH has no approved therapies, and liver fibrosis shows poor response to existing pharmacotherapy, in part due to an incomplete understanding of the underlying pathophysiology. Patient and mouse data have shown that NASH is associated with the activation of developmental pathways: Notch, Hedgehog and Hippo-YAP-TAZ. Although these evolutionarily conserved fundamental signals are known to determine liver morphogenesis during development, new data have shown a coordinated and causal role for these pathways in the liver injury response, which becomes maladaptive during obesity-associated chronic liver disease. In this Review, we discuss the aetiology of this reactivation of developmental pathways and review the cell-autonomous and cell-non-autonomous mechanisms by which developmental pathways influence disease progression. Finally, we discuss the potential prognostic and therapeutic implications of these data for NASH and liver fibrosis.
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11
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Kong Y, Zhao C, Huang Y, Liu Y, Liu S, Guo Y, Li M, Xu T, Zhao B, Wang J. Angiopoietin-like protein 4 promotes very-low-density lipoprotein assembly and secretion in bovine hepatocytes in vitro. IUBMB Life 2020; 72:2710-2721. [PMID: 33205615 DOI: 10.1002/iub.2403] [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: 08/11/2020] [Revised: 10/14/2020] [Accepted: 10/23/2020] [Indexed: 01/20/2023]
Abstract
In dairy cows, fatty liver is one of the most common metabolic diseases that occurs during the periparturient period. Angiopoietin-like protein 4 (ANGPTL4) is a well-known downstream target of peroxisome proliferator-activated receptors (PPARs), which regulate the glucose and fatty acid metabolisms. The inhibition of lipoprotein lipase (LPL) activity interferes with the storage of triglycerides (TG) in adipocytes, which plays an essential role in lipid metabolism in rodents. However, it remains unclear whether ANGPTL4 is involved in the pathological process of fatty liver in dairy cows as a result of the regulation of the hepatocellular lipid transport system. This study intended to investigate the effect of ANGPTL4 on the very-low-density lipoprotein (VLDL) assembly and secretion in bovine hepatocytes. Bovine hepatocytes were isolated using a modified two-step perfusion and collagenase digestion process, and treated with different concentrations of ANGPTL4 (0, 4, 12, and 24 ng/ml) for 24 hr. The results showed that a high concentration of ANGPTL4 could significantly increase the extracellular concentration of VLDL while reducing the intracellular content of TG. Thus, it was confirmed that ANGPTL4 could promote the transport of TG in the form of VLDL by partially regulating the expression of related proteins in hepatocytes, thereby contributing to the partial adaptive regulation of lipid transport in dairy cows.
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Affiliation(s)
- Yezi Kong
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Chenxu Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yan Huang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yaoquan Liu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Siqi Liu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yazhou Guo
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Manxia Li
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Tingxuan Xu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Baoyu Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Jianguo Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
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12
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Perfluoroctanoic acid (PFOA) enhances NOTCH-signaling in an angiogenesis model of placental trophoblast cells. Int J Hyg Environ Health 2020; 229:113566. [PMID: 32485599 DOI: 10.1016/j.ijheh.2020.113566] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/19/2020] [Accepted: 05/19/2020] [Indexed: 01/09/2023]
Abstract
Exposure to perfluoroalkyl substances (PFAS) was found to be associated with several pathological endpoints, including high cholesterol levels, specific defective functions of the immune system and reduced birth weight. While environmental PFAS have been recognized as threats for public health, surprisingly little is known about the underlying mechanisms of toxicity. We hypothesized that some of the observed vascular and developmental effects of environmental PFAS may share a common molecular pathway. At elevated levels of exposure to PFAS, a reduction in mean birth weight of newborns has been observed in combination with a high incidence rate of preeclampsia. As both, preeclampsia and reduced birth weight are consequences of an inadequate placental vascularization, we hypothesized that the adaptation of placental vasculature may get compromised by PFAS. We analyzed pseudo-vascular network formation and protein expression in the HTR8/SVneo cell line, an embryonic trophoblast cell type that is able to form vessel-like vascular networks in 3D-matrices, similar to endothelial cells. PFOA (perfluoroctanoic acid), but not PFOS (perfuoroctanesulfonic acid), induced morphological changes in the vascular 3D-network structure, without indications of compromised cellular viability. Incubation with PFOA reduced cellular sprouting and elongated isolated stalks in pseudo-vascular networks, while a γ-secretase inhibitor BMS-906024 induced directional opposite effects. We found a PFOA-induced increase in NOTCH intracellular domain (NICD) abundance in HTR8/SVneo, indicating that PFOA enhances NOTCH-signaling in this cell type. Enhancement of NOTCH-pathway by PFOA may be a key to understand the mode of action of PFAS, as this pathway is critically involved in many confirmed physiological/toxicological symptoms associated with PFAS exposure.
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13
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Kim K, Yu J, Kang JK, Morrow JP, Pajvani UB. Liver-selective γ-secretase inhibition ameliorates diet-induced hepatic steatosis, dyslipidemia and atherosclerosis. Biochem Biophys Res Commun 2020; 527:979-984. [PMID: 32439159 DOI: 10.1016/j.bbrc.2020.04.157] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 04/30/2020] [Indexed: 01/05/2023]
Abstract
Hepatic γ-secretase regulates low-density lipoprotein receptor (LDLR) cleavage and degradation, affecting clearance of plasma triglyceride (TG)-rich lipoproteins (TRLs). In this study, we investigated whether γ-secretase inhibition modulates risk of Western (high-fat/sucrose and high-cholesterol)-type diet (WTD)-induced hepatic steatosis, dyslipidemia and atherosclerosis. We evaluated liver and plasma lipids in WTD-fed mice with hepatocyte-specific ablation of the non-redundant γ-secretase-targeting subunit Nicastrin (L-Ncst). In parallel, we investigated the effect of liver-selective Ncst antisense oligonucleotides (ASO) on lipid metabolism and atherosclerosis in wildtype (WT) and ApoE knockout (ApoE-/-) mice fed normal chow or WTD. WTD-fed L-Ncst and Ncst ASO-treated WT mice showed reduced total cholesterol and LDL-cholesterol (LDL-C), as well as reduced hepatic lipid content as compared to Cre- and control ASO-treated WT mice. Treatment of WTD-fed ApoE-/- mice with Ncst ASO markedly lowered total and LDL cholesterol, hepatic TG and attenuated atherosclerotic lesions in the aorta, as compared to control ASO-treated mice. L-Ncst and Ncst ASO similarly showed reduced plasma glucose as compared to control mice. In conclusion, inhibition of hepatic γ-secretase reduces plasma glucose, and attenuates WTD-induced dyslipidemia, hepatic fat accumulation and atherosclerosis, suggesting potential pleiotropic application for diet-induced metabolic dysfunction.
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Affiliation(s)
- KyeongJin Kim
- Department of Medicine, Columbia University, New York, NY, 10032, USA; Department of Biomedical Sciences, College of Medicine, Inha University, Incheon, 22212, South Korea.
| | - Junjie Yu
- Department of Medicine, Columbia University, New York, NY, 10032, USA
| | - Jin Ku Kang
- Department of Medicine, Columbia University, New York, NY, 10032, USA
| | - John P Morrow
- Department of Medicine, Columbia University, New York, NY, 10032, USA
| | - Utpal B Pajvani
- Department of Medicine, Columbia University, New York, NY, 10032, USA.
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14
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Banerjee S, Andrew RJ, Duff CJ, Fisher K, Jackson CD, Lawrence CB, Maeda N, Greenspan DS, Kellett KAB, Hooper NM. Proteolysis of the low density lipoprotein receptor by bone morphogenetic protein-1 regulates cellular cholesterol uptake. Sci Rep 2019; 9:11416. [PMID: 31388055 PMCID: PMC6684651 DOI: 10.1038/s41598-019-47814-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 07/22/2019] [Indexed: 12/14/2022] Open
Abstract
The development of cardiovascular disease is intimately linked to elevated levels of low-density lipoprotein (LDL) cholesterol in the blood. Hepatic LDL receptor (LDLR) levels regulate the amount of plasma LDL. We identified the secreted zinc metalloproteinase, bone morphogenetic protein 1 (BMP1), as responsible for the cleavage of human LDLR within its extracellular ligand-binding repeats at Gly171↓Asp172. The resulting 120 kDa membrane-bound C-terminal fragment (CTF) of LDLR had reduced capacity to bind LDL and when expressed in LDLR null cells had compromised LDL uptake as compared to the full length receptor. Pharmacological inhibition of BMP1 or siRNA-mediated knockdown prevented the generation of the 120 kDa CTF and resulted in an increase in LDL uptake into cells. The 120 kDa CTF was detected in the livers from humans and mice expressing human LDLR. Collectively, these results identify that BMP1 regulates cellular LDL uptake and may provide a target to modulate plasma LDL cholesterol.
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Affiliation(s)
- Sreemoti Banerjee
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences, Manchester, M13 9PT, UK.,Jack Birch Unit for Molecular Carcinogenesis, Department of Biology, University of York, York, YO10 5DD, UK
| | - Robert J Andrew
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences, Manchester, M13 9PT, UK.,Department of Neurobiology, The University of Chicago, Chicago, IL, 60637, USA
| | - Christopher J Duff
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.,Department of Clinical Biochemistry, University Hospitals of North Midlands NHS Trust, Stoke-on-Trent, ST4 6QG, UK
| | - Kate Fisher
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences, Manchester, M13 9PT, UK
| | - Carolyn D Jackson
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Catherine B Lawrence
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences, Manchester, M13 9PT, UK
| | - Nobuyo Maeda
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Daniel S Greenspan
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Katherine A B Kellett
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences, Manchester, M13 9PT, UK.
| | - Nigel M Hooper
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Sciences, Manchester, M13 9PT, UK.
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15
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Bartolome A, Zhu C, Sussel L, Pajvani UB. Notch signaling dynamically regulates adult β cell proliferation and maturity. J Clin Invest 2018; 129:268-280. [PMID: 30375986 DOI: 10.1172/jci98098] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 10/25/2018] [Indexed: 12/13/2022] Open
Abstract
Notch signaling regulates differentiation of the pancreatic endocrine lineage during embryogenesis, but the role of Notch in mature β cells is unclear. We found that islets derived from lean mice show modest β cell Notch activity, which increases in obesity and in response to high glucose. This response appeared maladaptive, as mice with β cell-specific-deficient Notch transcriptional activity showed improved glucose tolerance when subjected to high-fat diet feeding. Conversely, mice with β cell-specific Notch gain of function (β-NICD) had a progressive loss of β cell maturity, due to proteasomal degradation of MafA, leading to impaired glucose-stimulated insulin secretion and glucose intolerance with aging or obesity. Surprisingly, Notch-active β cells had increased proliferative capacity, leading to increased but dysfunctional β cell mass. These studies demonstrate a dynamic role for Notch in developed β cells for simultaneously regulating β cell function and proliferation.
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Affiliation(s)
- Alberto Bartolome
- Department of Medicine, Columbia University, New York, New York, USA
| | - Changyu Zhu
- Department of Medicine, Columbia University, New York, New York, USA
| | - Lori Sussel
- Department of Pediatrics, University of Colorado, Denver, Colorado, USA
| | - Utpal B Pajvani
- Department of Medicine, Columbia University, New York, New York, USA
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16
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Zhu C, Kim K, Wang X, Bartolome A, Salomao M, Dongiovanni P, Meroni M, Graham MJ, Yates KP, Diehl AM, Schwabe RF, Tabas I, Valenti L, Lavine JE, Pajvani UB. Hepatocyte Notch activation induces liver fibrosis in nonalcoholic steatohepatitis. Sci Transl Med 2018; 10:10/468/eaat0344. [PMID: 30463916 PMCID: PMC6822168 DOI: 10.1126/scitranslmed.aat0344] [Citation(s) in RCA: 144] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 06/03/2018] [Accepted: 10/31/2018] [Indexed: 01/07/2023]
Abstract
Fibrosis is the major determinant of morbidity and mortality in patients with nonalcoholic steatohepatitis (NASH) but has no approved pharmacotherapy in part because of incomplete understanding of its pathogenic mechanisms. Here, we report that hepatocyte Notch activity tracks with disease severity and treatment response in patients with NASH and is similarly increased in a mouse model of diet-induced NASH and liver fibrosis. Hepatocyte-specific Notch loss-of-function mouse models showed attenuated NASH-associated liver fibrosis, demonstrating causality to obesity-induced liver pathology. Conversely, forced activation of hepatocyte Notch induced fibrosis in both chow- and NASH diet-fed mice by increasing Sox9-dependent Osteopontin (Opn) expression and secretion from hepatocytes, which activate resident hepatic stellate cells. In a cross-sectional study, we found that OPN explains the positive correlation between liver Notch activity and fibrosis stage in patients. Further, we developed a Notch inhibitor [Nicastrin antisense oligonucleotide (Ncst ASO)] that reduced fibrosis in NASH diet-fed mice. In summary, these studies demonstrate the pathological role and therapeutic accessibility of the maladaptive hepatocyte Notch response in NASH-associated liver fibrosis.
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Affiliation(s)
- Changyu Zhu
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - KyeongJin Kim
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Xiaobo Wang
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Alberto Bartolome
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Marcela Salomao
- Department of Pathology, Mayo Clinic, Phoenix, AZ 85054, USA
| | - Paola Dongiovanni
- Department of Pathophysiology and Transplantation, Università degli Studi Milano, and Internal Medicine and Metabolic Diseases, Fondazione IRCCS Ca’ Granda Ospedale Policlinico, Milan 20122, Italy
| | - Marica Meroni
- Department of Pathophysiology and Transplantation, Università degli Studi Milano, and Internal Medicine and Metabolic Diseases, Fondazione IRCCS Ca’ Granda Ospedale Policlinico, Milan 20122, Italy
| | | | - Katherine P. Yates
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Anna Mae Diehl
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - Robert F. Schwabe
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Ira Tabas
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Luca Valenti
- Department of Pathophysiology and Transplantation, Università degli Studi Milano, and Internal Medicine and Metabolic Diseases, Fondazione IRCCS Ca’ Granda Ospedale Policlinico, Milan 20122, Italy
| | - Joel E. Lavine
- Department of Pediatrics, Columbia University, New York, NY 10032, USA
| | - Utpal B. Pajvani
- Department of Medicine, Columbia University, New York, NY 10032, USA.,Corresponding author.
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17
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Zanoni P, Velagapudi S, Yalcinkaya M, Rohrer L, von Eckardstein A. Endocytosis of lipoproteins. Atherosclerosis 2018; 275:273-295. [PMID: 29980055 DOI: 10.1016/j.atherosclerosis.2018.06.881] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/04/2018] [Accepted: 06/22/2018] [Indexed: 02/06/2023]
Abstract
During their metabolism, all lipoproteins undergo endocytosis, either to be degraded intracellularly, for example in hepatocytes or macrophages, or to be re-secreted, for example in the course of transcytosis by endothelial cells. Moreover, there are several examples of internalized lipoproteins sequestered intracellularly, possibly to exert intracellular functions, for example the cytolysis of trypanosoma. Endocytosis and the subsequent intracellular itinerary of lipoproteins hence are key areas for understanding the regulation of plasma lipid levels as well as the biological functions of lipoproteins. Indeed, the identification of the low-density lipoprotein (LDL)-receptor and the unraveling of its transcriptional regulation led to the elucidation of familial hypercholesterolemia as well as to the development of statins, the most successful therapeutics for lowering of cholesterol levels and risk of atherosclerotic cardiovascular diseases. Novel limiting factors of intracellular trafficking of LDL and the LDL receptor continue to be discovered and to provide drug targets such as PCSK9. Surprisingly, the receptors mediating endocytosis of high-density lipoproteins or lipoprotein(a) are still a matter of controversy or even new discovery. Finally, the receptors and mechanisms, which mediate the uptake of lipoproteins into non-degrading intracellular itineraries for re-secretion (transcytosis, retroendocytosis), storage, or execution of intracellular functions, are largely unknown.
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Affiliation(s)
- Paolo Zanoni
- Institute for Clinical Chemistry, University and University Hospital Zurich, Zurich, Switzerland; Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Srividya Velagapudi
- Institute for Clinical Chemistry, University and University Hospital Zurich, Zurich, Switzerland; Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Mustafa Yalcinkaya
- Institute for Clinical Chemistry, University and University Hospital Zurich, Zurich, Switzerland; Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Lucia Rohrer
- Institute for Clinical Chemistry, University and University Hospital Zurich, Zurich, Switzerland; Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Arnold von Eckardstein
- Institute for Clinical Chemistry, University and University Hospital Zurich, Zurich, Switzerland; Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
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