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Toshima T, Yagi M, Do Y, Hirai H, Kunisaki Y, Kang D, Uchiumi T. Mitochondrial translation failure represses cholesterol gene expression via Pyk2-Gsk3β-Srebp2 axis. Life Sci Alliance 2024; 7:e202302423. [PMID: 38719751 PMCID: PMC11079605 DOI: 10.26508/lsa.202302423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 04/27/2024] [Accepted: 04/29/2024] [Indexed: 05/12/2024] Open
Abstract
Neurodegenerative diseases and other age-related disorders are closely associated with mitochondrial dysfunction. We previously showed that mice with neuron-specific deficiency of mitochondrial translation exhibit leukoencephalopathy because of demyelination. Reduced cholesterol metabolism has been associated with demyelinating diseases of the brain such as Alzheimer's disease. However, the molecular mechanisms involved and relevance to the pathogenesis remained unknown. In this study, we show that inhibition of mitochondrial translation significantly reduced expression of the cholesterol synthase genes and degraded their sterol-regulated transcription factor, sterol regulatory element-binding protein 2 (Srebp2). Furthermore, the phosphorylation of Pyk2 and Gsk3β was increased in the white matter of p32cKO mice. We observed that Pyk2 inhibitors reduced the phosphorylation of Gsk3β and that GSK3β inhibitors suppressed degradation of the transcription factor Srebp2. The Pyk2-Gsk3β axis is involved in the ubiquitination of Srebp2 and reduced expression of cholesterol gene. These results suggest that inhibition of mitochondrial translation may be a causative mechanism of neurodegenerative diseases of aging. Improving the mitochondrial translation or effectiveness of Gsk3β inhibitors is a potential therapeutic strategy for leukoencephalopathy.
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Affiliation(s)
- Takahiro Toshima
- https://ror.org/00p4k0j84 Department of Clinical Chemistry and Laboratory Medicine, Kyushu University, Fukuoka, Japan
- https://ror.org/00p4k0j84 Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Mikako Yagi
- https://ror.org/00p4k0j84 Department of Clinical Chemistry and Laboratory Medicine, Kyushu University, Fukuoka, Japan
- https://ror.org/00p4k0j84 Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Yura Do
- https://ror.org/00p4k0j84 Department of Clinical Chemistry and Laboratory Medicine, Kyushu University, Fukuoka, Japan
| | - Haruka Hirai
- https://ror.org/00p4k0j84 Department of Clinical Chemistry and Laboratory Medicine, Kyushu University, Fukuoka, Japan
- https://ror.org/00p4k0j84 Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Yuya Kunisaki
- https://ror.org/00p4k0j84 Department of Clinical Chemistry and Laboratory Medicine, Kyushu University, Fukuoka, Japan
| | - Dongchon Kang
- https://ror.org/00p4k0j84 Department of Clinical Chemistry and Laboratory Medicine, Kyushu University, Fukuoka, Japan
- Kashiigaoka Rehabilitation Hospital, Fukuoka, Japan
- Department of Medical Laboratory Science, Faculty of Health Sciences, Junshin Gakuen University, Fukuoka, Japan
| | - Takeshi Uchiumi
- https://ror.org/00p4k0j84 Department of Clinical Chemistry and Laboratory Medicine, Kyushu University, Fukuoka, Japan
- https://ror.org/00p4k0j84 Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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2
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Venegas M, Durán A, Campusano S, Barahona S, Sepúlveda D, Baeza M, Cifuentes V, Alcaíno J. Identification of Potential New Genes Related to the SREBP Pathway in Xanthophyllomyces dendrorhous. Biomolecules 2024; 14:778. [PMID: 39062491 PMCID: PMC11274570 DOI: 10.3390/biom14070778] [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: 06/12/2024] [Revised: 06/27/2024] [Accepted: 06/27/2024] [Indexed: 07/28/2024] Open
Abstract
The sterol regulatory element-binding protein (SREBP) pathway is an integral cellular mechanism that regulates lipid homeostasis, in which transcriptional activator SREBPs regulate the expression of various genes. In the carotenogenic yeast Xanthophyllomyces dendrorhous, Sre1 (the yeast SREBP homolog) regulates lipid biosynthesis and carotenogenesis, among other processes. Despite the characterization of several components of the SREBP pathway across various eukaryotes, the specific elements of this pathway in X. dendrorhous remain largely unknown. This study aimed to explore the potential regulatory mechanisms of the SREBP pathway in X. dendrorhous using the strain CBS.cyp61- as a model, which is known to have Sre1 in its active state under standard culture conditions, resulting in a carotenoid-overproducing phenotype. This strain was subjected to random mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine (NTG), followed by a screening methodology that focused on identifying mutants with altered Sre1 activation phenotypes. Single-nucleotide polymorphism (SNP) analysis of 20 selected mutants detected 5439 single-nucleotide variants (SNVs), narrowing them down to 1327 SNPs of interest after a series of filters. Classification based on SNP impact identified 116 candidate genes, including 49 genes with high impact and 68 genes with deleterious moderate-impact mutations. BLAST, InterProScan, and gene ontology enrichment analyses highlighted 25 genes as potential participants in regulating Sre1 in X. dendrorhous. The key findings of this study include the identification of genes potentially encoding proteins involved in protein import/export to the nucleus, sterol biosynthesis, the ubiquitin-proteasome system, protein regulatory activities such as deacetylases, a subset of kinases and proteases, as well as transcription factors that could be influential in SREBP regulation. These findings are expected to significantly contribute to the current understanding of the intricate regulation of the transcription factor Sre1 in X. dendrorhous, providing valuable groundwork for future research and potential biotechnological applications.
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Affiliation(s)
- Maximiliano Venegas
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago 7800003, Chile; (M.V.)
| | - Alejandro Durán
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago 7800003, Chile; (M.V.)
| | - Sebastián Campusano
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago 7800003, Chile; (M.V.)
| | - Salvador Barahona
- Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago 7800003, Chile
| | - Dionisia Sepúlveda
- Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago 7800003, Chile
| | - Marcelo Baeza
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago 7800003, Chile; (M.V.)
| | - Víctor Cifuentes
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago 7800003, Chile; (M.V.)
| | - Jennifer Alcaíno
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Santiago 7800003, Chile; (M.V.)
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Wang Y, Engel T, Teng X. Post-translational regulation of the mTORC1 pathway: A switch that regulates metabolism-related gene expression. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2024; 1867:195005. [PMID: 38242428 DOI: 10.1016/j.bbagrm.2024.195005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 12/15/2023] [Accepted: 01/03/2024] [Indexed: 01/21/2024]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is a kinase complex that plays a crucial role in coordinating cell growth in response to various signals, including amino acids, growth factors, oxygen, and ATP. Activation of mTORC1 promotes cell growth and anabolism, while its suppression leads to catabolism and inhibition of cell growth, enabling cells to withstand nutrient scarcity and stress. Dysregulation of mTORC1 activity is associated with numerous diseases, such as cancer, metabolic disorders, and neurodegenerative conditions. This review focuses on how post-translational modifications, particularly phosphorylation and ubiquitination, modulate mTORC1 signaling pathway and their consequential implications for pathogenesis. Understanding the impact of phosphorylation and ubiquitination on the mTORC1 signaling pathway provides valuable insights into the regulation of cellular growth and potential therapeutic targets for related diseases.
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Affiliation(s)
- Yitao Wang
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China; Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, Dublin D02 YN77, Ireland
| | - Tobias Engel
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, University of Medicine and Health Sciences, Dublin D02 YN77, Ireland; FutureNeuro, SFI Research Centre for Chronic and Rare Neurological Diseases, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland
| | - Xinchen Teng
- College of Pharmaceutical Sciences, Soochow University, Suzhou, Jiangsu 215123, China.
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4
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Lan T, Geng XJ, Zhang SJ, Zeng XX, Ying JJ, Xu Y, Liu SY, Li P, Tong YH, Wang W, Mao ZJ, Wang SW. Si-Ni-San inhibits hepatic Fasn expression and lipid accumulation in MAFLD mice through AMPK/p300/SREBP-1c axis. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2024; 123:155209. [PMID: 37984123 DOI: 10.1016/j.phymed.2023.155209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 10/22/2023] [Accepted: 11/09/2023] [Indexed: 11/22/2023]
Abstract
BACKGROUND Soothing the liver and regulating qi is one of the core ideas of traditional Chinese medicine (TCM) in the treatment of fatty liver. Si-Ni-San (SNS) is a well-known herbal formula in TCM for liver soothing and qi regulation in fatty liver treatment. However, its efficacy lacks modern scientific evidence. PURPOSE This study was aimed to investigate the impact of SNS on metabolic associated fatty liver disease (MAFLD) in mice and explore the underlying molecular mechanisms, particularly its effects on lipid metabolism in hepatocytes. METHODS The therapeutic effect of SNS was evaluated using in vivo and in vitro models of high-fat/high-cholesterol (HFHC) diet-induced mice and palmitic acid (PA)-induced hepatocytes, respectively. Molecular biological techniques such as RNA-sequencing (RNA-seq), co-immunoprecipitation (co-IP), and western blotting were employed to elucidate the molecular mechanism of SNS in regulating lipid metabolism in hepatocytes. RESULTS Our findings revealed that SNS effectively reduced lipid accumulation in the livers of HFHC diet-induced mice and PA-induced hepatocytes. RNA-seq analysis demonstrated that SNS significantly down-regulated the expression of fatty acid synthase (Fasn) in the livers of HFHC-fed mice. Mechanistically, SNS inhibited Fasn expression and lipid accumulation by activating adenosine monophosphate (AMP)-activated protein kinase (AMPK). Activation of AMPK suppressed the activity of the transcriptional coactivator p300 and modulated the protein stability of sterol regulatory element-binding protein-1c (SREBP-1c). Importantly, p300 was required for the inhibition of Fasn expression and lipid accumulation by SNS. Furthermore, SNS activated AMPK by decreasing adenosine triphosphate (ATP) production in hepatocytes. CONCLUSION This study provided novel evidence on the regulatory mechanisms underlying the effects of SNS on Fasn expression. Our findings demonstrate, for the first time, that SNS exerts suppressive effects on Fasn expression through modulation of the AMPK/p300/SREBP-1c axis. Consequently, this regulatory pathway mitigates excessive lipid accumulation and ameliorates MAFLD in mice.
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Affiliation(s)
- Tian Lan
- The Joint Innovation Center for Health & Medicine, the Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou 324000, China
| | - Xiao-Juan Geng
- College of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Si-Jia Zhang
- College of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Xi-Xi Zeng
- The Joint Innovation Center for Health & Medicine, the Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou 324000, China
| | - Jun-Jie Ying
- The Joint Innovation Center for Health & Medicine, the Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou 324000, China
| | - Yi Xu
- The Joint Innovation Center for Health & Medicine, the Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou 324000, China
| | - Shi-Yu Liu
- College of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Ping Li
- College of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Yu-Hua Tong
- The Joint Innovation Center for Health & Medicine, the Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou 324000, China; Department of Ophthalmology, The Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou 324000, China
| | - Wen Wang
- Preventive Treatment Center, Zhejiang Chinese Medical University Affiliated Four-provinces Marginal Hospital of Traditional Chinese Medicine, Quzhou Hospital of Traditional Chinese Medicine, Quzhou 324000, China.
| | - Zhu-Jun Mao
- College of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou 310053, China; Department of Ophthalmology, The Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou 324000, China.
| | - Si-Wei Wang
- The Joint Innovation Center for Health & Medicine, the Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou 324000, China.
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5
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Bolshette N, Ezagouri S, Dandavate V, Karavaeva I, Golik M, Wang H, Espenshade PJ, Osborne TF, Han X, Asher G. Carbon dioxide regulates cholesterol levels through SREBP2. PLoS Biol 2023; 21:e3002367. [PMID: 37967106 PMCID: PMC10651039 DOI: 10.1371/journal.pbio.3002367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 10/06/2023] [Indexed: 11/17/2023] Open
Abstract
In mammals, O2 and CO2 levels are tightly regulated and are altered under various pathological conditions. While the molecular mechanisms that participate in O2 sensing are well characterized, little is known regarding the signaling pathways that participate in CO2 signaling and adaptation. Here, we show that CO2 levels control a distinct cellular transcriptional response that differs from mere pH changes. Unexpectedly, we discovered that CO2 regulates the expression of cholesterogenic genes in a SREBP2-dependent manner and modulates cellular cholesterol accumulation. Molecular dissection of the underlying mechanism suggests that CO2 triggers SREBP2 activation through changes in endoplasmic reticulum (ER) membrane cholesterol levels. Collectively, we propose that SREBP2 participates in CO2 signaling and that cellular cholesterol levels can be modulated by CO2 through SREBP2.
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Affiliation(s)
- Nityanand Bolshette
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Saar Ezagouri
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Vaishnavi Dandavate
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Iuliia Karavaeva
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Marina Golik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Hu Wang
- The Sam & Ann Barshop Institute for Longevity & Aging Studies, University of Texas Health Science Center, San Antonio, Texas, United States of America
| | - Peter J. Espenshade
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Timothy F. Osborne
- Institute for Fundamental Biomedical Research, Johns Hopkins All Children’s Hospital, and Medicine in the Division of Endocrinology, Diabetes and Metabolism of the Johns Hopkins University School of Medicine, Petersburg, Florida, United States of America
| | - Xianlin Han
- The Sam & Ann Barshop Institute for Longevity & Aging Studies, University of Texas Health Science Center, San Antonio, Texas, United States of America
| | - Gad Asher
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
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6
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Maier CR, Hartmann O, Prieto-Garcia C, Al-Shami KM, Schlicker L, Vogel FCE, Haid S, Klann K, Buck V, Münch C, Schmitz W, Einig E, Krenz B, Calzado MA, Eilers M, Popov N, Rosenfeldt MT, Diefenbacher ME, Schulze A. USP28 controls SREBP2 and the mevalonate pathway to drive tumour growth in squamous cancer. Cell Death Differ 2023:10.1038/s41418-023-01173-6. [PMID: 37202505 DOI: 10.1038/s41418-023-01173-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 04/16/2023] [Accepted: 04/25/2023] [Indexed: 05/20/2023] Open
Abstract
SREBP2 is a master regulator of the mevalonate pathway (MVP), a biosynthetic process that drives the synthesis of dolichol, heme A, ubiquinone and cholesterol and also provides substrates for protein prenylation. Here, we identify SREBP2 as a novel substrate for USP28, a deubiquitinating enzyme that is frequently upregulated in squamous cancers. Our results show that silencing of USP28 reduces expression of MVP enzymes and lowers metabolic flux into this pathway. We also show that USP28 binds to mature SREBP2, leading to its deubiquitination and stabilisation. USP28 depletion rendered cancer cells highly sensitive to MVP inhibition by statins, which was rescued by the addition of geranyl-geranyl pyrophosphate. Analysis of human tissue microarrays revealed elevated expression of USP28, SREBP2 and MVP enzymes in lung squamous cell carcinoma (LSCC) compared to lung adenocarcinoma (LADC). Moreover, CRISPR/Cas-mediated deletion of SREBP2 selectively attenuated tumour growth in a KRas/p53/LKB1 mutant mouse model of lung cancer. Finally, we demonstrate that statins synergise with a dual USP28/25 inhibitor to reduce viability of SCC cells. Our findings suggest that combinatorial targeting of MVP and USP28 could be a therapeutic strategy for the treatment of squamous cell carcinomas.
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Affiliation(s)
- Carina R Maier
- German Cancer Research Center, Division of Tumor Metabolism and Microenvironment, Im Neuenheimer Feld 581, 69120, Heidelberg, Germany
- Protein Stability and Cancer Group, Department of Biochemistry and Molecular Biology, Theodor-Boveri-Institute, Biocenter, Am Hubland, 97074, Würzburg, Germany
| | - Oliver Hartmann
- Protein Stability and Cancer Group, Department of Biochemistry and Molecular Biology, Theodor-Boveri-Institute, Biocenter, Am Hubland, 97074, Würzburg, Germany
| | - Cristian Prieto-Garcia
- Protein Stability and Cancer Group, Department of Biochemistry and Molecular Biology, Theodor-Boveri-Institute, Biocenter, Am Hubland, 97074, Würzburg, Germany
- Institute of Biochemistry II, Goethe University Frankfurt, Theodor-Stern-Kai 7, Haus 75, 60590, Frankfurt am Main, Germany
| | - Kamal M Al-Shami
- German Cancer Research Center, Division of Tumor Metabolism and Microenvironment, Im Neuenheimer Feld 581, 69120, Heidelberg, Germany
| | - Lisa Schlicker
- German Cancer Research Center, Division of Tumor Metabolism and Microenvironment, Im Neuenheimer Feld 581, 69120, Heidelberg, Germany
| | - Felix C E Vogel
- German Cancer Research Center, Division of Tumor Metabolism and Microenvironment, Im Neuenheimer Feld 581, 69120, Heidelberg, Germany
| | - Silke Haid
- German Cancer Research Center, Division of Tumor Metabolism and Microenvironment, Im Neuenheimer Feld 581, 69120, Heidelberg, Germany
| | - Kevin Klann
- Institute of Biochemistry II, Goethe University Frankfurt, Theodor-Stern-Kai 7, Haus 75, 60590, Frankfurt am Main, Germany
| | - Viktoria Buck
- Institute of Pathology, Julius Maximilians University and Comprehensive Cancer Center (CCC) Mainfranken, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - Christian Münch
- Institute of Biochemistry II, Goethe University Frankfurt, Theodor-Stern-Kai 7, Haus 75, 60590, Frankfurt am Main, Germany
| | - Werner Schmitz
- Theodor Boveri Institute, Department of Biochemistry and Molecular Biology, Biocenter, University of Würzburg, 97074, Würzburg, Germany
| | - Elias Einig
- Internal Medicine VIII-Clinical Tumor Biology, University of Tübingen, Otfried-Müller-Straße 14, 72076, Tübingen, Germany
| | - Bastian Krenz
- Theodor Boveri Institute, Department of Biochemistry and Molecular Biology, Biocenter, University of Würzburg, 97074, Würzburg, Germany
| | - Marco A Calzado
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain
- Departamento de Biología Celular, Fisiología e Inmunología, Universidad de Córdoba, Córdoba, Spain
- Hospital Universitario Reina Sofía, Córdoba, Spain
| | - Martin Eilers
- Theodor Boveri Institute, Department of Biochemistry and Molecular Biology, Biocenter, University of Würzburg, 97074, Würzburg, Germany
| | - Nikita Popov
- Internal Medicine VIII-Clinical Tumor Biology, University of Tübingen, Otfried-Müller-Straße 14, 72076, Tübingen, Germany
| | - Mathias T Rosenfeldt
- Institute of Pathology, Julius Maximilians University and Comprehensive Cancer Center (CCC) Mainfranken, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - Markus E Diefenbacher
- Protein Stability and Cancer Group, Department of Biochemistry and Molecular Biology, Theodor-Boveri-Institute, Biocenter, Am Hubland, 97074, Würzburg, Germany.
| | - Almut Schulze
- German Cancer Research Center, Division of Tumor Metabolism and Microenvironment, Im Neuenheimer Feld 581, 69120, Heidelberg, Germany.
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Jeon YG, Kim YY, Lee G, Kim JB. Physiological and pathological roles of lipogenesis. Nat Metab 2023; 5:735-759. [PMID: 37142787 DOI: 10.1038/s42255-023-00786-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 03/15/2023] [Indexed: 05/06/2023]
Abstract
Lipids are essential metabolites, which function as energy sources, structural components and signalling mediators. Most cells are able to convert carbohydrates into fatty acids, which are often converted into neutral lipids for storage in the form of lipid droplets. Accumulating evidence suggests that lipogenesis plays a crucial role not only in metabolic tissues for systemic energy homoeostasis but also in immune and nervous systems for their proliferation, differentiation and even pathophysiological roles. Thus, excessive or insufficient lipogenesis is closely associated with aberrations in lipid homoeostasis, potentially leading to pathological consequences, such as dyslipidaemia, diabetes, fatty liver, autoimmune diseases, neurodegenerative diseases and cancers. For systemic energy homoeostasis, multiple enzymes involved in lipogenesis are tightly controlled by transcriptional and post-translational modifications. In this Review, we discuss recent findings regarding the regulatory mechanisms, physiological roles and pathological importance of lipogenesis in multiple tissues such as adipose tissue and the liver, as well as the immune and nervous systems. Furthermore, we briefly introduce the therapeutic implications of lipogenesis modulation.
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Affiliation(s)
- Yong Geun Jeon
- Center for Adipocyte Structure and Function, Institute of Molecular Biology and Genetics, School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Ye Young Kim
- Center for Adipocyte Structure and Function, Institute of Molecular Biology and Genetics, School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Gung Lee
- Center for Adipocyte Structure and Function, Institute of Molecular Biology and Genetics, School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Jae Bum Kim
- Center for Adipocyte Structure and Function, Institute of Molecular Biology and Genetics, School of Biological Sciences, Seoul National University, Seoul, South Korea.
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8
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Kamoshita K, Ishii KA, Tahira Y, Kikuchi A, Abuduwaili H, Tajima-Shirasaki N, Li Q, Takayama H, Matsumoto K, Takamura T. Insulin Suppresses Ubiquitination via the Deubiquitinating Enzyme Ubiquitin-Specific Protease 14, Independent of Proteasome Activity in H4IIEC3 Hepatocytes. J Pharmacol Exp Ther 2023; 385:5-16. [PMID: 36328485 DOI: 10.1124/jpet.122.001088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 08/16/2022] [Accepted: 09/09/2022] [Indexed: 11/06/2022] Open
Abstract
Ubiquitin-proteasome dysfunction contributes to obesity-related metabolic disorders, such as diabetes and fatty liver disease. However, the regulation of ubiquitin-proteasome activity by insulin remains to be elucidated. Here, we show that prolonged insulin stimulation activates proteasome function even though it reduces the ubiquitinated proteins in H4IIEC3 hepatocytes. Looking for a pathway by which insulin inhibits ubiquitination, we found that hepatic expression of ubiquitin-specific protease 14 (USP14) was upregulated in the liver of patients with insulin resistance. Indeed, the USP14-specific inhibitor IU1 canceled the insulin-mediated reduction of ubiquitinated proteins. Furthermore, insulin-induced endoplasmic reticulum (ER) stress, which was canceled by IU1, suggesting that USP14 activity is involved in insulin-induced ER stress. Co-stimulation with insulin and IU1 for 2 hours upregulated the nuclear translocation of the lipogenic transcription factor, sterol regulatory element binding protein-1c (SREBP-1c), upregulated the expression of the lipogenic gene, fatty acid synthase (Fasn), and repressed the gluconeogenic genes. In conclusion, insulin activates proteasome function even though it inhibits protein ubiquitination by activating USP14 in hepatocytes. USP14 activation by insulin inhibits mature SREBP-1c while upregulating ER stress and the expression of genes involved in gluconeogenesis. Further understanding mechanisms underlying the USP14 activation and its pleiotropic effects may lead to therapeutic development for obesity-associated metabolic disorders, such as diabetes and fatty liver disease. SIGNIFICANCE STATEMENT: This study shows that insulin stimulation inhibits ubiquitination by activating USP14, independent of its effect on proteasome activity in hepatocytes. USP14 also downregulates the nuclear translocation of the lipogenic transcription factor SREBP-1c and upregulates the expression of genes involved in gluconeogenesis. Since USP14 is upregulated in the liver of insulin-resistant patients, understanding mechanisms underlying the USP14 activation and its pleiotropic effects will help develop treatments for metabolic disorders such as diabetes and fatty liver.
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Affiliation(s)
- Kyoko Kamoshita
- Department of Endocrinology and Metabolism, Graduate School of Medical Sciences (K.K., K.A.I., Y.T., A.K., H.A., N.T.S., Q.L., H.T., T.T.); Department of Integrative Medicine for Longevity, Graduate School of Medical Sciences (K.A.I.); Life Sciences Division, Engineering and Technology Department (H.T.); and Division of Tumor Dynamics and Regulation, Cancer Research Institute (K.M.), Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Kiyo-Aki Ishii
- Department of Endocrinology and Metabolism, Graduate School of Medical Sciences (K.K., K.A.I., Y.T., A.K., H.A., N.T.S., Q.L., H.T., T.T.); Department of Integrative Medicine for Longevity, Graduate School of Medical Sciences (K.A.I.); Life Sciences Division, Engineering and Technology Department (H.T.); and Division of Tumor Dynamics and Regulation, Cancer Research Institute (K.M.), Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Yumiko Tahira
- Department of Endocrinology and Metabolism, Graduate School of Medical Sciences (K.K., K.A.I., Y.T., A.K., H.A., N.T.S., Q.L., H.T., T.T.); Department of Integrative Medicine for Longevity, Graduate School of Medical Sciences (K.A.I.); Life Sciences Division, Engineering and Technology Department (H.T.); and Division of Tumor Dynamics and Regulation, Cancer Research Institute (K.M.), Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Akihiro Kikuchi
- Department of Endocrinology and Metabolism, Graduate School of Medical Sciences (K.K., K.A.I., Y.T., A.K., H.A., N.T.S., Q.L., H.T., T.T.); Department of Integrative Medicine for Longevity, Graduate School of Medical Sciences (K.A.I.); Life Sciences Division, Engineering and Technology Department (H.T.); and Division of Tumor Dynamics and Regulation, Cancer Research Institute (K.M.), Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Halimulati Abuduwaili
- Department of Endocrinology and Metabolism, Graduate School of Medical Sciences (K.K., K.A.I., Y.T., A.K., H.A., N.T.S., Q.L., H.T., T.T.); Department of Integrative Medicine for Longevity, Graduate School of Medical Sciences (K.A.I.); Life Sciences Division, Engineering and Technology Department (H.T.); and Division of Tumor Dynamics and Regulation, Cancer Research Institute (K.M.), Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Natsumi Tajima-Shirasaki
- Department of Endocrinology and Metabolism, Graduate School of Medical Sciences (K.K., K.A.I., Y.T., A.K., H.A., N.T.S., Q.L., H.T., T.T.); Department of Integrative Medicine for Longevity, Graduate School of Medical Sciences (K.A.I.); Life Sciences Division, Engineering and Technology Department (H.T.); and Division of Tumor Dynamics and Regulation, Cancer Research Institute (K.M.), Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Qifang Li
- Department of Endocrinology and Metabolism, Graduate School of Medical Sciences (K.K., K.A.I., Y.T., A.K., H.A., N.T.S., Q.L., H.T., T.T.); Department of Integrative Medicine for Longevity, Graduate School of Medical Sciences (K.A.I.); Life Sciences Division, Engineering and Technology Department (H.T.); and Division of Tumor Dynamics and Regulation, Cancer Research Institute (K.M.), Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Hiroaki Takayama
- Department of Endocrinology and Metabolism, Graduate School of Medical Sciences (K.K., K.A.I., Y.T., A.K., H.A., N.T.S., Q.L., H.T., T.T.); Department of Integrative Medicine for Longevity, Graduate School of Medical Sciences (K.A.I.); Life Sciences Division, Engineering and Technology Department (H.T.); and Division of Tumor Dynamics and Regulation, Cancer Research Institute (K.M.), Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Kunio Matsumoto
- Department of Endocrinology and Metabolism, Graduate School of Medical Sciences (K.K., K.A.I., Y.T., A.K., H.A., N.T.S., Q.L., H.T., T.T.); Department of Integrative Medicine for Longevity, Graduate School of Medical Sciences (K.A.I.); Life Sciences Division, Engineering and Technology Department (H.T.); and Division of Tumor Dynamics and Regulation, Cancer Research Institute (K.M.), Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Toshinari Takamura
- Department of Endocrinology and Metabolism, Graduate School of Medical Sciences (K.K., K.A.I., Y.T., A.K., H.A., N.T.S., Q.L., H.T., T.T.); Department of Integrative Medicine for Longevity, Graduate School of Medical Sciences (K.A.I.); Life Sciences Division, Engineering and Technology Department (H.T.); and Division of Tumor Dynamics and Regulation, Cancer Research Institute (K.M.), Kanazawa University, Kanazawa, Ishikawa, Japan
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9
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Bengoechea-Alonso MT, Aldaalis A, Ericsson J. Loss of the Fbw7 tumor suppressor rewires cholesterol metabolism in cancer cells leading to activation of the PI3K-AKT signalling axis. Front Oncol 2022; 12:990672. [PMID: 36176395 PMCID: PMC9513553 DOI: 10.3389/fonc.2022.990672] [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: 07/10/2022] [Accepted: 08/18/2022] [Indexed: 11/13/2022] Open
Abstract
The sterol regulatory-element binding proteins (SREBPs) are transcription factors controlling cholesterol and fatty acid synthesis and metabolism. There are three SREBP proteins, SREBP1a, SREBP1c and SREBP2, with SREBP1a being the strongest transcription factor. The expression of SREBP1a is restricted to rapidly proliferating cells, including cancer cells. The SREBP proteins are translated as large, inactive precursors bound to the endoplasmic reticulum (ER) membranes. These precursors undergo a two-step cleavage process that releases the amino terminal domains of the proteins, which translocate to the nucleus and function as transcription factors. The nuclear forms of the SREBPs are rapidly degraded by the ubiquitin-proteasome system in a manner dependent on the Fbw7 ubiquitin ligase. Consequently, inactivation of Fbw7 results in the stabilization of active SREBP1 and SREBP2 and enhanced expression of target genes. We report that the inactivation of Fbw7 in cancer cells blocks the proteolytic maturation of SREBP2. The same is true in cells expressing a cancer-specific loss-of-function Fbw7 protein. Interestingly, the activation of SREBP2 is restored in response to cholesterol depletion, suggesting that Fbw7-deficient cells accumulate cholesterol. Importantly, inactivation of SREBP1 in Fbw7-deficient cells also restores the cholesterol-dependent regulation of SREBP2, suggesting that the stabilization of active SREBP1 molecules could be responsible for the blunted activation of SREBP2 in Fbw7-deficient cancer cells. We suggest that this could be an important negative feedback loop in cancer cells with Fbw7 loss-of-function mutations to protect these cells from the accumulation of toxic levels of cholesterol and/or cholesterol metabolites. Surprisingly, we also found that the inactivation of Fbw7 resulted in the activation of AKT. Importantly, the activation of AKT was dependent on SREBP1 and on the accumulation of cholesterol. Thus, we suggest that the loss of Fbw7 rewires lipid metabolism in cancer cells to support cell proliferation and survival.
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Affiliation(s)
- Maria T. Bengoechea-Alonso
- Division of Biological and Biomedical Sciences, College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| | - Arwa Aldaalis
- Division of Biological and Biomedical Sciences, College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
| | - Johan Ericsson
- Division of Biological and Biomedical Sciences, College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar
- School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
- *Correspondence: Johan Ericsson,
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10
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Aldaalis A, Bengoechea-Alonso MT, Ericsson J. The SREBP-dependent regulation of cyclin D1 coordinates cell proliferation and lipid synthesis. Front Oncol 2022; 12:942386. [PMID: 36091143 PMCID: PMC9451027 DOI: 10.3389/fonc.2022.942386] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 07/25/2022] [Indexed: 12/15/2022] Open
Abstract
The sterol regulatory-element binding protein (SREBP) family of transcription factors regulates cholesterol, fatty acid, and triglyceride synthesis and metabolism. However, they are also targeted by the ubiquitin ligase Fbw7, a major tumor suppressor, suggesting that they could regulate cell growth. Indeed, enhanced lipid synthesis is a hallmark of many human tumors. Thus, the SREBP pathway has recently emerged as a potential target for cancer therapy. We have previously demonstrated that one of these transcription factors, SREBP1, is stabilized and remains associated with target promoters during mitosis, suggesting that the expression of these target genes could be important as cells enter G1 and transcription is restored. Activation of cyclin D-cdk4/6 complexes is critical for the phosphorylation and inactivation of the retinoblastoma protein (Rb) family of transcriptional repressors and progression through the G1 phase of the cell cycle. Importantly, the cyclin D-cdk4/6-Rb regulatory axis is frequently dysregulated in human cancer. In the current manuscript, we demonstrate that SREBP1 activates the expression of cyclin D1, a coactivator of cdk4 and cdk6, by binding to an E-box in the cyclin D1 promoter. Consequently, inactivation of SREBP1 in human liver and breast cancer cell lines reduces the expression of cyclin D1 and attenuates Rb phosphorylation. Rb phosphorylation in these cells can be rescued by restoring cyclin D1 expression. On the other hand, expression of active SREBP1 induced the expression of cyclin D1 and increased the phosphorylation of Rb in a manner dependent on cyclin D1 and cdk4/6 activity. Inactivation of SREBP1 resulted in reduced expression of cyclin D1, attenuated phosphorylation of Rb, and reduced proliferation. Inactivation of SREBP1 also reduced the insulin-dependent regulation of the cyclin D1 gene. At the same time, SREBP1 is known to play an important role in supporting lipid synthesis in cancer cells. Thus, we propose that the SREBP1-dependent regulation of cyclin D1 coordinates cell proliferation with the enhanced lipid synthesis required to support cell growth.
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Affiliation(s)
- Arwa Aldaalis
- Division of Biological and Biomedical Sciences, College of Health and Life Sciences, Hamad Bin Khalifa University, Education City, Doha, Qatar
| | - Maria T. Bengoechea-Alonso
- Division of Biological and Biomedical Sciences, College of Health and Life Sciences, Hamad Bin Khalifa University, Education City, Doha, Qatar
| | - Johan Ericsson
- Division of Biological and Biomedical Sciences, College of Health and Life Sciences, Hamad Bin Khalifa University, Education City, Doha, Qatar
- School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
- *Correspondence: Johan Ericsson,
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11
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Carvalho-Gontijo R, Han C, Zhang L, Zhang V, Hosseini M, Mekeel K, Schnabl B, Loomba R, Karin M, Brenner DA, Kisseleva T. Metabolic Injury of Hepatocytes Promotes Progression of NAFLD and AALD. Semin Liver Dis 2022; 42:233-249. [PMID: 36001995 PMCID: PMC9662188 DOI: 10.1055/s-0042-1755316] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Nonalcoholic liver disease is a component of metabolic syndrome associated with obesity, insulin resistance, and hyperlipidemia. Excessive alcohol consumption may accelerate the progression of steatosis, steatohepatitis, and fibrosis. While simple steatosis is considered a benign condition, nonalcoholic steatohepatitis with inflammation and fibrosis may progress to cirrhosis, liver failure, and hepatocellular cancer. Studies in rodent experimental models and primary cell cultures have demonstrated several common cellular and molecular mechanisms in the pathogenesis and regression of liver fibrosis. Chronic injury and death of hepatocytes cause the recruitment of myeloid cells, secretion of inflammatory and fibrogenic cytokines, and activation of myofibroblasts, resulting in liver fibrosis. In this review, we discuss the role of metabolically injured hepatocytes in the pathogenesis of nonalcoholic steatohepatitis and alcohol-associated liver disease. Specifically, the role of chemokine production and de novo lipogenesis in the development of steatotic hepatocytes and the pathways of steatosis regulation are discussed.
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Affiliation(s)
- Raquel Carvalho-Gontijo
- Department of Medicine, University of California, San Diego School of Medicine, La Jolla,Department of Surgery, University of California, San Diego School of Medicine, La Jolla
| | - Cuijuan Han
- Department of Medicine, University of California, San Diego School of Medicine, La Jolla,Department of Surgery, University of California, San Diego School of Medicine, La Jolla
| | - Lei Zhang
- Department of Medicine, University of California, San Diego School of Medicine, La Jolla,Department of Surgery, University of California, San Diego School of Medicine, La Jolla
| | - Vivian Zhang
- Department of Medicine, University of California, San Diego School of Medicine, La Jolla,Department of Surgery, University of California, San Diego School of Medicine, La Jolla
| | - Mojgan Hosseini
- Department of Pathology, University of California, San Diego School of Medicine, La Jolla
| | - Kristin Mekeel
- Department of Surgery, University of California, San Diego School of Medicine, La Jolla
| | - Bernd Schnabl
- Department of Medicine, University of California, San Diego School of Medicine, La Jolla
| | - Rohit Loomba
- Department of Medicine, University of California, San Diego School of Medicine, La Jolla
| | - Michael Karin
- Department of Pharmacology, University of California, San Diego School of Medicine, La Jolla
| | - David A. Brenner
- Department of Medicine, University of California, San Diego School of Medicine, La Jolla
| | - Tatiana Kisseleva
- Department of Surgery, University of California, San Diego School of Medicine, La Jolla,Corresponding author: Tatiana Kisseleva, 9500 Gilman Drive, #0063, La Jolla, California 92093, USA. Phone: 858.822.5339,
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12
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Miyata S, Kodaka M, Kikuchi A, Matsunaga Y, Shoji K, Kuan YC, Iwase M, Takeda K, Katsuta R, Ishigami K, Matsumoto Y, Suzuki T, Yamamoto Y, Sato R, Inoue J. Sulforaphane suppresses the activity of sterol regulatory element-binding proteins (SREBPs) by promoting SREBP precursor degradation. Sci Rep 2022; 12:8715. [PMID: 35610278 PMCID: PMC9130306 DOI: 10.1038/s41598-022-12347-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 05/09/2022] [Indexed: 12/26/2022] Open
Abstract
Sterol regulatory element-binding proteins (SREBPs) are transcription factors that regulate various genes involved in cholesterol and fatty acid synthesis. In this study, we describe that naturally occurring isothiocyanate sulforaphane (SFaN) impairs fatty acid synthase promoter activity and reduces SREBP target gene (e.g., fatty acid synthase and acetyl-CoA carboxylase 1) expression in human hepatoma Huh-7 cells. SFaN reduced SREBP proteins by promoting the degradation of the SREBP precursor. Amino acids 595–784 of SREBP-1a were essential for SFaN-mediated SREBP-1a degradation. We also found that such SREBP-1 degradation occurs independently of the SREBP cleavage-activating protein and the Keap1-Nrf2 pathway. This study identifies SFaN as an SREBP inhibitor and provides evidence that SFaN could have major potential as a pharmaceutical preparation against hepatic steatosis and obesity.
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Affiliation(s)
- Shingo Miyata
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657, Japan
| | - Manami Kodaka
- Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo, 156-8502, Japan
| | - Akito Kikuchi
- Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo, 156-8502, Japan
| | - Yuki Matsunaga
- Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo, 156-8502, Japan
| | - Kenta Shoji
- Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo, 156-8502, Japan
| | - Yen-Chou Kuan
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657, Japan.,Department of Horticulture and Landscape Architecture, College of Bioresources and Agriculture, National Taiwan University, Taipei, Taiwan
| | - Masamori Iwase
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657, Japan
| | - Keita Takeda
- Department of Chemistry for Life Sciences and Agriculture, Tokyo University of Agriculture, Tokyo, 156-8502, Japan
| | - Ryo Katsuta
- Department of Chemistry for Life Sciences and Agriculture, Tokyo University of Agriculture, Tokyo, 156-8502, Japan
| | - Ken Ishigami
- Department of Chemistry for Life Sciences and Agriculture, Tokyo University of Agriculture, Tokyo, 156-8502, Japan
| | - Yu Matsumoto
- Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo, 156-8502, Japan
| | - Tsukasa Suzuki
- Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo, 156-8502, Japan
| | - Yuji Yamamoto
- Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo, 156-8502, Japan
| | - Ryuichiro Sato
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657, Japan.
| | - Jun Inoue
- Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo, 156-8502, Japan.
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13
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Shen W, Zhou Q, Peng C, Li J, Yuan Q, Zhu H, Zhao M, Jiang X, Liu W, Ren C. FBXW7 and the Hallmarks of Cancer: Underlying Mechanisms and Prospective Strategies. Front Oncol 2022; 12:880077. [PMID: 35515121 PMCID: PMC9063462 DOI: 10.3389/fonc.2022.880077] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 03/15/2022] [Indexed: 12/13/2022] Open
Abstract
FBXW7, a member of the F-box protein family within the ubiquitin–proteasome system, performs an indispensable role in orchestrating cellular processes through ubiquitination and degradation of its substrates, such as c-MYC, mTOR, MCL-1, Notch, and cyclin E. Mainly functioning as a tumor suppressor, inactivation of FBXW7 induces the aberrations of its downstream pathway, resulting in the occurrence of diseases especially tumorigenesis. Here, we decipher the relationship between FBXW7 and the hallmarks of cancer and discuss the underlying mechanisms. Considering the interplay of cancer hallmarks, we propose several prospective strategies for circumventing the deficits of therapeutic resistance and complete cure of cancer patients.
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Affiliation(s)
- Wenyue Shen
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Quanwei Zhou
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Chenxi Peng
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Jiaheng Li
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Qizhi Yuan
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Hecheng Zhu
- Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, China.,Changsha Kexin Cancer Hospital, Changsha, China
| | - Ming Zhao
- Changsha Kexin Cancer Hospital, Changsha, China
| | - Xingjun Jiang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Weidong Liu
- Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, China.,The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health and the Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, School of Basic Medicine, Central South University, Changsha, China
| | - Caiping Ren
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China.,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China.,Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, China.,The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health and the Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, School of Basic Medicine, Central South University, Changsha, China
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14
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Yan SQ, Adi D, Liu C, Wang MM, Abuzhalihana J, Wu Y, Fu ZY, Yang YN, Li XM, Xie X, Liu F, Chen BD, Ma YT. FBXW7 gene polymorphism is associated with type 2 diabetes in the Uygur population in Xinjiang, China. Hereditas 2021; 158:27. [PMID: 34372947 PMCID: PMC8351158 DOI: 10.1186/s41065-021-00191-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 07/19/2021] [Indexed: 11/22/2022] Open
Abstract
Background FBXW7 gene expression is positively correlated with glycolipid metabolism and is associated with diabetes in animal models. In the current study, we focused on exploring whether genetic variants of the FBXW7 gene were associated with type 2 diabetes (T2DM) and the risk factors for T2DM in Uygur people in Xinjiang, China. Methods A total of 2164 Chinese Uygur subjects (673 T2DM patients and 1491 controls) were recruited for our case–control study, and four SNPs (rs10033601, rs2255137, rs2292743 and rs35311955) of the FBXW7 gene were genotyped using the improved multiplex ligation detection reaction (iMLDR) technique. Results Our study showed that the genotypes using the overdominant model (GA vs AA + GG) of rs10033601 and using the overdominant model (TA vs TT + AA) of rs2292743 were significantly different between T2DM patients and the controls (P = 0.005 and P = 0.012, respectively). After multivariate adjustments for confounders, the rs10033601 and rs2292743 SNPs were still independent risk factors for T2DM [GA vs AA + GG: odds ratio = 1.35, 95% confidence interval (CI) = 1.12–1.64, P = 0.002; TA vs TT + AA: OR = 1.28, 95% CI = 1.06–1.55, P = 0.011]. Participants within the Chinese Uygur populations and who with the GA genotype of rs10033601 and the TA genotype of rs2292743 were associated with significantly elevated glucose levels. Conclusions Our study revealed that both rs10033601 and rs2292743 of the FBXW7 gene were associated with T2DM in the Uygur populations in Xinjiang.
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Affiliation(s)
- Shi-Qi Yan
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Dilare Adi
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Cheng Liu
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Meng-Meng Wang
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Jialin Abuzhalihana
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Yun Wu
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Zhen-Yan Fu
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Yi-Ning Yang
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Xiao-Mei Li
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Xiang Xie
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China.,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Fen Liu
- Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Bang-Dang Chen
- Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China
| | - Yi-Tong Ma
- Department of Cardiology, First Affiliated Hospital of Xinjiang Medical University, Urumqi, 830054, P.R. China. .,Xinjiang Key Laboratory of Cardiovascular Disease Research, Urumqi, 830054, P.R. China.
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15
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Lipid Regulatory Proteins as Potential Therapeutic Targets for Ovarian Cancer in Obese Women. Cancers (Basel) 2020; 12:cancers12113469. [PMID: 33233362 PMCID: PMC7700662 DOI: 10.3390/cancers12113469] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 02/07/2023] Open
Abstract
Obesity has become a recognized global epidemic that is associated with numerous comorbidities including type II diabetes, cardiovascular disease, hypertension, and cancer incidence and progression. Ovarian cancer (OvCa) has a unique mechanism of intra-peritoneal metastasis, already present in 80% of women at the time of diagnosis, making it the fifth leading cause of death from gynecological malignancy. Meta-analyses showed that obesity increases the risk of OvCa progression, leads to enhanced overall and organ-specific tumor burden, and adversely effects survival of women with OvCa. Recent data discovered that tumors grown in mice fed on a western diet (40% fat) have elevated lipid levels and a highly increased expression level of sterol regulatory element binding protein 1 (SREBP1). SREBP1 is a master transcription factor that regulates de novo lipogenesis and lipid homeostasis, and induces lipogenic reprogramming of tumor cells. Elevated SREBP1 levels are linked to cancer cell proliferation and metastasis. This review will summarize recent findings to provide a current understanding of lipid regulatory proteins in the ovarian tumor microenvironment with emphasis on SREBP1 expression in the obese host, the role of SREBP1 in cancer progression and metastasis, and potential therapeutic targeting of SREBPs and SREBP-pathway genes in treating cancers, particularly in the context of host obesity.
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16
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Identification of a degradation signal at the carboxy terminus of SREBP2: A new role for this domain in cholesterol homeostasis. Proc Natl Acad Sci U S A 2020; 117:28080-28091. [PMID: 33106423 DOI: 10.1073/pnas.2018578117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Lipid homeostasis in animal cells is maintained by sterol regulatory element-binding proteins (SREBPs), membrane-bound transcription factors whose proteolytic activation requires the cholesterol-sensing membrane protein Scap. In endoplasmic reticulum (ER) membranes, the carboxyl-terminal domain (CTD) of SREBPs binds to the CTD of Scap. When cholesterol levels are low, Scap escorts SREBPs from the ER to the Golgi, where the actions of two proteases release the amino-terminal domains of SREBPs that travel to the nucleus to up-regulate expression of lipogenic genes. The CTD of SREBP remains bound to Scap but must be eliminated so that Scap can be recycled to bind and transport additional SREBPs. Here, we provide insights into how this occurs by performing a detailed molecular dissection of the CTD of SREBP2, one of three SREBP isoforms expressed in mammals. We identify a degradation signal comprised of seven noncontiguous amino acids encoded in exon 19 that mediates SREBP2's proteasomal degradation in the absence of Scap. When bound to the CTD of Scap, this signal is masked and SREBP2 is stabilized. Binding to Scap requires an arginine residue in exon 18 of SREBP2. After SREBP2 is cleaved in Golgi, its CTD remains bound to Scap and returns to the ER with Scap where it is eliminated by proteasomal degradation. The Scap-binding motif, but not the degradation signal, is conserved in SREBP1. SREBP1's stability is determined by a degradation signal in a different region of its CTD. These findings highlight a previously unknown role for the CTD of SREBPs in regulating SREBP activity.
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17
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Asif S, Morrow NM, Mulvihill EE, Kim KH. Understanding Dietary Intervention-Mediated Epigenetic Modifications in Metabolic Diseases. Front Genet 2020; 11:590369. [PMID: 33193730 PMCID: PMC7593700 DOI: 10.3389/fgene.2020.590369] [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: 08/01/2020] [Accepted: 09/21/2020] [Indexed: 12/12/2022] Open
Abstract
The global prevalence of metabolic disorders, such as obesity, diabetes and fatty liver disease, is dramatically increasing. Both genetic and environmental factors are well-known contributors to the development of these diseases and therefore, the study of epigenetics can provide additional mechanistic insight. Dietary interventions, including caloric restriction, intermittent fasting or time-restricted feeding, have shown promising improvements in patients' overall metabolic profiles (i.e., reduced body weight, improved glucose homeostasis), and an increasing number of studies have associated these beneficial effects with epigenetic alterations. In this article, we review epigenetic changes involved in both metabolic diseases and dietary interventions in primary metabolic tissues (i.e., adipose, liver, and pancreas) in hopes of elucidating potential biomarkers and therapeutic targets for disease prevention and treatment.
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Affiliation(s)
- Shaza Asif
- University of Ottawa Heart Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Nadya M. Morrow
- University of Ottawa Heart Institute, Ottawa, ON, Canada
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Erin E. Mulvihill
- University of Ottawa Heart Institute, Ottawa, ON, Canada
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Kyoung-Han Kim
- University of Ottawa Heart Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
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18
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Butler LM, Perone Y, Dehairs J, Lupien LE, de Laat V, Talebi A, Loda M, Kinlaw WB, Swinnen JV. Lipids and cancer: Emerging roles in pathogenesis, diagnosis and therapeutic intervention. Adv Drug Deliv Rev 2020; 159:245-293. [PMID: 32711004 PMCID: PMC7736102 DOI: 10.1016/j.addr.2020.07.013] [Citation(s) in RCA: 303] [Impact Index Per Article: 75.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 07/02/2020] [Accepted: 07/16/2020] [Indexed: 02/06/2023]
Abstract
With the advent of effective tools to study lipids, including mass spectrometry-based lipidomics, lipids are emerging as central players in cancer biology. Lipids function as essential building blocks for membranes, serve as fuel to drive energy-demanding processes and play a key role as signaling molecules and as regulators of numerous cellular functions. Not unexpectedly, cancer cells, as well as other cell types in the tumor microenvironment, exploit various ways to acquire lipids and extensively rewire their metabolism as part of a plastic and context-dependent metabolic reprogramming that is driven by both oncogenic and environmental cues. The resulting changes in the fate and composition of lipids help cancer cells to thrive in a changing microenvironment by supporting key oncogenic functions and cancer hallmarks, including cellular energetics, promoting feedforward oncogenic signaling, resisting oxidative and other stresses, regulating intercellular communication and immune responses. Supported by the close connection between altered lipid metabolism and the pathogenic process, specific lipid profiles are emerging as unique disease biomarkers, with diagnostic, prognostic and predictive potential. Multiple preclinical studies illustrate the translational promise of exploiting lipid metabolism in cancer, and critically, have shown context dependent actionable vulnerabilities that can be rationally targeted, particularly in combinatorial approaches. Moreover, lipids themselves can be used as membrane disrupting agents or as key components of nanocarriers of various therapeutics. With a number of preclinical compounds and strategies that are approaching clinical trials, we are at the doorstep of exploiting a hitherto underappreciated hallmark of cancer and promising target in the oncologist's strategy to combat cancer.
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Affiliation(s)
- Lisa M Butler
- Adelaide Medical School and Freemasons Foundation Centre for Men's Health, University of Adelaide, Adelaide, SA 5005, Australia; South Australian Health and Medical Research Institute, Adelaide, SA 5000, Australia
| | - Ylenia Perone
- Department of Surgery and Cancer, Imperial College London, Imperial Centre for Translational and Experimental Medicine, London, UK
| | - Jonas Dehairs
- Laboratory of Lipid Metabolism and Cancer, KU Leuven Cancer Institute, 3000 Leuven, Belgium
| | - Leslie E Lupien
- Program in Experimental and Molecular Medicine, Geisel School of Medicine at Dartmouth, 1 Medical Center Drive, Lebanon, NH 037560, USA
| | - Vincent de Laat
- Laboratory of Lipid Metabolism and Cancer, KU Leuven Cancer Institute, 3000 Leuven, Belgium
| | - Ali Talebi
- Laboratory of Lipid Metabolism and Cancer, KU Leuven Cancer Institute, 3000 Leuven, Belgium
| | - Massimo Loda
- Pathology and Laboratory Medicine, Weill Cornell Medical College, Cornell University, New York, NY 10065, USA
| | - William B Kinlaw
- The Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, 1 Medical Center Drive, Lebanon, NH 03756, USA
| | - Johannes V Swinnen
- Laboratory of Lipid Metabolism and Cancer, KU Leuven Cancer Institute, 3000 Leuven, Belgium.
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19
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Chua NK, Coates HW, Brown AJ. Squalene monooxygenase: a journey to the heart of cholesterol synthesis. Prog Lipid Res 2020; 79:101033. [DOI: 10.1016/j.plipres.2020.101033] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/21/2020] [Accepted: 04/24/2020] [Indexed: 02/07/2023]
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20
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Heo MJ, Kang SH, Kim YS, Lee JM, Yu J, Kim HR, Lim H, Kim KM, Jung J, Jeong LS, Moon A, Kim SG. UBC12-mediated SREBP-1 neddylation worsens metastatic tumor prognosis. Int J Cancer 2020; 147:2550-2563. [PMID: 32449166 DOI: 10.1002/ijc.33113] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 04/07/2020] [Accepted: 04/30/2020] [Indexed: 12/29/2022]
Abstract
Activation of sterol regulatory element-binding protein 1 (SREBP-1), a master lipogenic transcription factor, is associated with cancer metabolism and metabolic disorders. Neddylation, the process of adding NEDD8 to its substrate, contributes to diverse biological processes. Here, we identified SREBP-1 as a substrate for neddylation by UBC12 and explored its impact on tumor aggressiveness. In cell-based assays, SREBP-1 neddylation prolonged SREBP-1 stability with a decrease in ubiquitination. Consequently, NEDD8 overexpression facilitated proliferation, migration, and invasion of SK-Hep1 liver tumor cells. MLN4924 (an inhibitor of the NEDD8-activating enzyme-E1) treatment or UBC12 knockdown prevented SREBP-1 neddylation and tumor cell phenotype change. This effect was corroborated in an in vivo xenograft model. In human specimens, SREBP-1, UBC12, and NEDD8 were all upregulated in hepatocellular carcinoma (HCC) compared to nontumorous regions. Moreover, SREBP-1 levels positively correlated with UBC12. In GEO database analyses, SREBP-1 levels were greater in metastatic HCC samples accompanying UBC12 upregulation. In HCC analysis, tumoral SREBP-1 and UBC12 levels discriminated overall patient survival rates. Additionally, MLN4924 treatment destabilized SREBP-1 in MDA-MB-231 breast cancer cells and in the tumor cell xenograft. SREBP-1 and UBC12 were also highly expressed in human breast cancer tissues. Moreover, most breast cancers with lymph node metastasis displayed predominant SREBP-1 and UBC12 expressions, which compromised overall patient survival rates. In summary, SREBP-1 is neddylated by UBC12, which may contribute to HCC and breast cancer aggressiveness through SREBP-1 stabilization, and these events can be intervented by MLN4924 therapy. Our findings may also provide potential reliable prognostic markers for tumor metastasis.
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Affiliation(s)
- Mi Jeong Heo
- College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Sung Hyun Kang
- College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Yun Seok Kim
- College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Jung Min Lee
- College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Jinha Yu
- College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Hong-Rae Kim
- College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Hyesol Lim
- Duksung Innovative Drug Center, College of Pharmacy, Duksung Women's University, Seoul, South Korea
| | - Kyoung Mee Kim
- Duksung Innovative Drug Center, College of Pharmacy, Duksung Women's University, Seoul, South Korea
| | - Joohee Jung
- Duksung Innovative Drug Center, College of Pharmacy, Duksung Women's University, Seoul, South Korea
| | - Lak Shin Jeong
- College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Aree Moon
- Duksung Innovative Drug Center, College of Pharmacy, Duksung Women's University, Seoul, South Korea
| | - Sang Geon Kim
- College of Pharmacy, Seoul National University, Seoul, South Korea
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21
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Ju UI, Jeong DW, Seo J, Park JB, Park JW, Suh KS, Kim JB, Chun YS. Neddylation of sterol regulatory element-binding protein 1c is a potential therapeutic target for nonalcoholic fatty liver treatment. Cell Death Dis 2020; 11:283. [PMID: 32332706 PMCID: PMC7181738 DOI: 10.1038/s41419-020-2472-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 12/27/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a risk factor for progression of steatohepatitis, liver cirrhosis, and liver cancer. Although pathological condition of NAFLD, which arises from an excessive accumulation of triglyceride in the liver, is accompanied by elevated sterol regulatory element-binding protein 1c (SREBP1c) level, it is largely unknown which factors are involved in the modification of SREBP1c. In this study, we discovered that neddylation of SREBP1c competes with its ubiquitination and stabilizes SREBP1c protein level, and eventually promotes hepatic steatosis. We also demonstrated that human homolog of mouse double minute 2 (HDM2) acts as an E3 neddylation ligase of SREBP1c. Further, treatment with the neddylation inhibitor, MLN4924, attenuates high-fat diet-induced hepatic steatosis by reducing the levels of SREBP1c protein and hepatic triglyceride. Our results indicate that the blockade of SREBP1c neddylation could be a novel approach in the defense against NAFLD.
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Affiliation(s)
- Uk-Il Ju
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea
| | - Do-Won Jeong
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea
| | - Jieun Seo
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea
| | - Jun Bum Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea
| | - Jong-Wan Park
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Korea
| | - Kyung-Suk Suh
- Department of Hepatobiliary and Pancreatic Surgery, Seoul National University Hospital, Seoul, Korea
| | - Jae Bum Kim
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul, Korea
| | - Yang-Sook Chun
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea.
- Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul, Korea.
- Department of Physiology, Seoul National University College of Medicine, Seoul, Korea.
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22
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Fatty liver diseases, mechanisms, and potential therapeutic plant medicines. Chin J Nat Med 2020; 18:161-168. [PMID: 32245585 DOI: 10.1016/s1875-5364(20)30017-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Indexed: 02/07/2023]
Abstract
The liver is an important metabolic organ and controls lipid, glucose and energy metabolism. Dysruption of hepatic lipid metabolism is often associated with fatty liver diseases, including nonalcoholic fatty liver disease (NAFLD), alcoholic fatty liver diseases (AFLD) and hyperlipidemia. Recent studies have uncovered the contribution of hormones, transcription factors, and inflammatory cytokines to the pathogenesis of dyslipidemia and fatty liver diseases. Moreover, a significant amount of effort has been put to examine the mechanisms underlying the potential therapeutic effects of many natural plant products on fatty liver diseases and metabolic diseases. We review the current understanding of insulin, thyroid hormone and inflammatory cytokines in regulating hepatic lipid metabolism, focusing on several essential transcription regulators, such as Sirtuins (SIRTs), Forkhead box O (FoxO), Sterol-regulatory element-binding proteins (SREBPs). We also discuss a few representative natural products with promising thereapeutic effects on fatty liver disease and dyslipidemia.
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23
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Sahoo S, Singh D, Chakraborty P, Jolly MK. Emergent Properties of the HNF4α-PPARγ Network May Drive Consequent Phenotypic Plasticity in NAFLD. J Clin Med 2020; 9:E870. [PMID: 32235813 PMCID: PMC7141525 DOI: 10.3390/jcm9030870] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/15/2020] [Accepted: 03/18/2020] [Indexed: 02/06/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease in adults and children. It is characterized by excessive accumulation of lipids in the hepatocytes of patients without any excess alcohol intake. With a global presence of 24% and limited therapeutic options, the disease burden of NAFLD is increasing. Thus, it becomes imperative to attempt to understand the dynamics of disease progression at a systems-level. Here, we decoded the emergent dynamics of underlying gene regulatory networks that were identified to drive the initiation and the progression of NAFLD. We developed a mathematical model to elucidate the dynamics of the HNF4α-PPARγ gene regulatory network. Our simulations reveal that this network can enable multiple co-existing phenotypes under certain biological conditions: an adipocyte, a hepatocyte, and a "hybrid" adipocyte-like state of the hepatocyte. These phenotypes may also switch among each other, thus enabling phenotypic plasticity and consequently leading to simultaneous deregulation of the levels of molecules that maintain a hepatic identity and/or facilitate a partial or complete acquisition of adipocytic traits. These predicted trends are supported by the analysis of clinical data, further substantiating the putative role of phenotypic plasticity in driving NAFLD. Our results unravel how the emergent dynamics of underlying regulatory networks can promote phenotypic plasticity, thereby propelling the clinically observed changes in gene expression often associated with NAFLD.
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Affiliation(s)
- Sarthak Sahoo
- Undergraduate Programme, Indian Institute of Science, Bangalore 560012, India
| | - Divyoj Singh
- Undergraduate Programme, Indian Institute of Science, Bangalore 560012, India
| | - Priyanka Chakraborty
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Mohit Kumar Jolly
- Centre for BioSystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India
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24
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Dorotea D, Koya D, Ha H. Recent Insights Into SREBP as a Direct Mediator of Kidney Fibrosis via Lipid-Independent Pathways. Front Pharmacol 2020; 11:265. [PMID: 32256356 PMCID: PMC7092724 DOI: 10.3389/fphar.2020.00265] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 02/24/2020] [Indexed: 12/17/2022] Open
Abstract
Sterol regulatory-element binding proteins (SREBPs) are classical regulators of cellular lipid metabolism in the kidney and other tissues. SREBPs are currently recognized as versatile transcription factors involved in a myriad of cellular processes. Meanwhile, SREBPs have been recognized to mediate lipotoxicity, contributing to the progression of kidney diseases. SREBP1 has been shown to bind to the promoter region of TGFβ, a major pro-fibrotic signaling mechanism in the kidney. Conversely, TGFβ activates SREBP1 transcriptional activity suggesting a positive feedback loop of SREBP1 in TGFβ signaling. Public ChIP-seq data revealed numerous non-lipid transcriptional targets of SREBPs that plausibly play roles in progressive kidney disease and fibrosis. This review provides new insights into SREBP as a mediator of kidney fibrosis via lipid-independent pathways.
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Affiliation(s)
- Debra Dorotea
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, South Korea
| | - Daisuke Koya
- Department of Internal Medicine, Kanazawa Medical University, Ishikawa, Japan
| | - Hunjoo Ha
- Graduate School of Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul, South Korea
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25
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Sharma B, Gupta V, Dahiya D, Kumar H, Vaiphei K, Agnihotri N. Clinical relevance of cholesterol homeostasis genes in colorectal cancer. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:1314-1327. [PMID: 31202724 DOI: 10.1016/j.bbalip.2019.06.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/31/2019] [Accepted: 06/10/2019] [Indexed: 12/12/2022]
Abstract
Accumulation of cholesterol is a well-known feature in cancer. Preclinical studies suggest the contribution of various cholesterol regulators in CRC. However, their clinical relevance remains poorly understood. The aim of the present study is to evaluate the expression of these modulators in CRC and elucidate their diagnostic and prognostic value. mRNA levels of HMGCR, SREBF2, NR1H3 and NR1H2 were downregulated in tumors in local and TCGA cohort. The expression of LDLR, ABCA1 and SCARB1 was not consistent in the two cohorts. Western Blot analysis showed the increased levels of LDLR and reduced levels of LXR in early stage patients. Tumoral SREBP2 levels were enhanced in early stage whereas decreased in late stage. The individual expression of HMGCR, SREBF2, NR1H3 and NR1H2 did not have the potential to be used as independent prognostic marker, however, the combined expression of these genes associated with poor clinical outcome independent of lymph node metastasis, distant metastasis and advanced stage. This work sheds light on deregulation of cholesterol uptake and efflux pathways and provides novel leads in the development of biomarkers and therapeutic regimens that can detect and target CRC at initial stages.
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Affiliation(s)
- Bhoomika Sharma
- Department of Biochemistry, Panjab University, Sector-25, Chandigarh 160014, India
| | - Vikas Gupta
- Department of General Surgery, Post Graduate Institute of Medical Education & Research (PGIMER),Sector 12, Chandigarh 160012, India
| | - Divya Dahiya
- Department of General Surgery, Post Graduate Institute of Medical Education & Research (PGIMER),Sector 12, Chandigarh 160012, India
| | - Hemanth Kumar
- Department of General Surgery, Post Graduate Institute of Medical Education & Research (PGIMER),Sector 12, Chandigarh 160012, India
| | - Kim Vaiphei
- Department of Histopathology, Post Graduate Institute of Medical Education & Research (PGIMER), Sector 12, Chandigarh 160012, India.
| | - Navneet Agnihotri
- Department of Biochemistry, Panjab University, Sector-25, Chandigarh 160014, India.
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26
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Chassin H, Müller M, Tigges M, Scheller L, Lang M, Fussenegger M. A modular degron library for synthetic circuits in mammalian cells. Nat Commun 2019; 10:2013. [PMID: 31043592 PMCID: PMC6494899 DOI: 10.1038/s41467-019-09974-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 04/04/2019] [Indexed: 01/26/2023] Open
Abstract
Tight control over protein degradation is a fundamental requirement for cells to respond rapidly to various stimuli and adapt to a fluctuating environment. Here we develop a versatile, easy-to-handle library of destabilizing tags (degrons) for the precise regulation of protein expression profiles in mammalian cells by modulating target protein half-lives in a predictable manner. Using the well-established tetracycline gene-regulation system as a model, we show that the dynamics of protein expression can be tuned by fusing appropriate degron tags to gene regulators. Next, we apply this degron library to tune a synthetic pulse-generating circuit in mammalian cells. With this toolbox we establish a set of pulse generators with tailored pulse lengths and magnitudes of protein expression. This methodology will prove useful in the functional roles of essential proteins, fine-tuning of gene-expression systems, and enabling a higher complexity in the design of synthetic biological systems in mammalian cells.
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Affiliation(s)
- Hélène Chassin
- Department of Biosystems Science and Engineering, ETH Zürich, Mattenstrasse 26, CH-4058, Basel, Switzerland
| | - Marius Müller
- Cilag AG, Hochstrasse 201, CH-8200, Schaffhausen, Switzerland
| | - Marcel Tigges
- Cilag AG, Hochstrasse 201, CH-8200, Schaffhausen, Switzerland
| | - Leo Scheller
- Department of Biosystems Science and Engineering, ETH Zürich, Mattenstrasse 26, CH-4058, Basel, Switzerland
| | - Moritz Lang
- Institute of Science and Technology Austria, A-3400, Klosterneuburg, Austria
| | - Martin Fussenegger
- Department of Biosystems Science and Engineering, ETH Zürich, Mattenstrasse 26, CH-4058, Basel, Switzerland.
- Faculty of Science, University of Basel, Mattenstrasse 26, CH-4058, Basel, Switzerland.
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27
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Iwase M, Watanabe K, Shimizu M, Suzuki T, Yamamoto Y, Inoue J, Sato R. Chrysin reduces the activity and protein level of mature forms of sterol regulatory element-binding proteins. Biosci Biotechnol Biochem 2019; 83:1740-1746. [PMID: 31021712 DOI: 10.1080/09168451.2019.1608806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Sterol regulatory element-binding proteins (SREBPs) are transcription factors that regulate the expression of genes involved in fatty acid and cholesterol biosynthetic pathways. The present study showed that the flavonoid chrysin impairs the fatty acid synthase promoter. Chrysin reduces the expression of SREBP target genes, such as fatty acid synthase, in human hepatoma Huh-7 cells and impairs de novo synthesis of fatty acids and cholesterol. Moreover, it reduces the endogenous mature, transcriptionally active forms of SREBPs, which are generated by the proteolytic processing of precursor forms. In addition, chrysin reduces the enforced expressing mature forms of SREBPs and their transcriptional activity. The ubiquitin-proteasome system is not involved in the chrysin-mediated reduction of SREBPs mature forms. These results suggest that chrysin suppresses SREBP activity, at least partially, via the degradation of SREBPs mature forms. Abbreviations: ACC1: acetyl-CoA carboxylase 1; DMEM: Dulbecco's modified Eagle's medium; FAS: fatty acid synthase; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; 25-HC: 25-hydroxycholesterol; HMGCS: HMG-CoA synthase; LDH: lactate dehydrogenase; LPDS: lipoprotein-deficient serum; PI3K: phosphatidylinositol 3-kinase; SCD1: stearoyl-CoA desaturase; SREBPs: sterol regulatory element-binding proteins.
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Affiliation(s)
- Masamori Iwase
- a Food Biochemistry laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan
| | - Kyoko Watanabe
- b Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture , Tokyo , Japan
| | - Makoto Shimizu
- a Food Biochemistry laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan
| | - Tsukasa Suzuki
- b Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture , Tokyo , Japan
| | - Yuji Yamamoto
- b Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture , Tokyo , Japan
| | - Jun Inoue
- a Food Biochemistry laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan.,b Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture , Tokyo , Japan
| | - Ryuichiro Sato
- a Food Biochemistry laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan.,c Nutri-Life Science laboratory, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan
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28
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Bjune K, Sundvold H, Leren TP, Naderi S. MK-2206, an allosteric inhibitor of AKT, stimulates LDLR expression and LDL uptake: A potential hypocholesterolemic agent. Atherosclerosis 2018; 276:28-38. [PMID: 30025252 DOI: 10.1016/j.atherosclerosis.2018.07.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 06/01/2018] [Accepted: 07/06/2018] [Indexed: 01/22/2023]
Abstract
BACKGROUND AND AIMS Induction of low-density lipoprotein receptor (LDLR) plays a significant role in reduction of plasma LDL-cholesterol (LDL-C) levels. Therefore, strategies that enhance the protein level of LDLR provide an attractive therapeutic target for the treatment of hypercholesterolemia. With this aim in mind, we concentrated our effort on studying the role of AKT kinase in regulation of LDLR levels and proceeded to examine the effect of MK-2206, an allosteric and highly selective AKT inhibitor, on LDLR expression. METHODS Cultured human hepatoma cells were used to examine the effect of MK-2206 on the proteolytic processing of sterol regulatory element-binding protein-2 (SREBP-2), the expression of LDLR and cellular internalization of LDL. We also examined the effect of MK-2206 on LDLR levels in primary human hepatocytes. RESULTS MK-2206 induced the proteolytic processing of SREBP-2, upregulated LDLR expression and stimulated LDL uptake. In contrast to statins, induction of LDLR levels by MK-2206 did not rely on 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) inhibition. As a result, cotreatment of cells with MK-2206 and mevastatin potentiated the impact of mevastatin on LDLR. Importantly, MK-2206 stimulated the expression of LDLR by primary human hepatocytes. CONCLUSIONS MK-2206 is a novel LDLR-inducing agent that, either alone or in combination with statins, exerts a stimulating effect on cellular LDL uptake.
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Affiliation(s)
- Katrine Bjune
- Unit for Cardiac and Cardiovascular Genetics, Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Hilde Sundvold
- Unit for Cardiac and Cardiovascular Genetics, Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Trond P Leren
- Unit for Cardiac and Cardiovascular Genetics, Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
| | - Soheil Naderi
- Unit for Cardiac and Cardiovascular Genetics, Department of Medical Genetics, Oslo University Hospital, Oslo, Norway.
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29
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Inoue J, Miyata S, Shimizu M, Sato R. Isoxanthohumol stimulates ubiquitin-proteasome-dependent degradation of precursor forms of sterol regulatory element-binding proteins. Biosci Biotechnol Biochem 2018; 82:1591-1598. [PMID: 29804513 DOI: 10.1080/09168451.2018.1478715] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Sterol regulatory element-binding proteins (SREBPs) are transcription factors that regulate a wide variety of genes involved in fatty acid and cholesterol synthesis. In the present study, we identified that isoxanthohumol (IXN) suppressed SREBP activity. Low concentrations of IXN (10 and 30 μM) reduced the amount of mature forms of SREBPs, while high concentration of IXN (100 μM) reduced both precursor and mature forms of SREBPs in Huh-7 cells. The IXN-mediated decrease in the precursor forms of SREBPs in Huh-7 cells was completely abolished by culturing cells under sterol-supplemented conditions and was partly abolished by treatment with a proteasome inhibitor, MG132, but not a lysosome inhibitor, NH4Cl. Moreover, IXN accelerated the ubiquitination of the precursor forms of SREBP-1a. These results suggest that IXN suppresses SREBP activity, at least in part, via ubiquitin-proteasome-dependent degradation of the precursor forms of SREBPs. ABBREVIATIONS ACC1: acetyl-CoA carboxylase 1; DMEM: Dulbecco's modified Eagle's medium; ER: endoplasmic reticulum; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; 25-HC: 25-hydroxycholesterol; HMGCR: HMG-CoA reductase; HMGCS: HMG-CoA synthase; Insig: insulin-induced gene; IXN: isoxanthohumol; LPDS: lipoprotein-deficient serum; SCAP: SREBP cleavage-activating protein; SCD1: stearoyl-CoA desaturase; SREBPs: sterol regulatory element-binding proteins; XN: xanthohumol.
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Affiliation(s)
- Jun Inoue
- a Department of Agricultural Chemistry, Faculty of Applied Biosciences , Tokyo University of Agriculture , Tokyo , Japan.,b Food Biochemistry laboratory, Department of Applied Biological Chemistry , Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan
| | - Shingo Miyata
- b Food Biochemistry laboratory, Department of Applied Biological Chemistry , Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan
| | - Makoto Shimizu
- b Food Biochemistry laboratory, Department of Applied Biological Chemistry , Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan
| | - Ryuichiro Sato
- b Food Biochemistry laboratory, Department of Applied Biological Chemistry , Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan.,c Nutri-Life Science laboratory, Department of Applied Biological Chemistry , Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan
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30
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Physiological functions of FBW7 in cancer and metabolism. Cell Signal 2018; 46:15-22. [PMID: 29474981 DOI: 10.1016/j.cellsig.2018.02.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 02/16/2018] [Accepted: 02/18/2018] [Indexed: 12/11/2022]
Abstract
FBW7 is one of the most well characterized F-box proteins that serve as substrate recognition subunits of SCF (Skp1-Cullin 1-F-box proteins) E3 ubiquitin ligase complexes. SCFFBW7 plays key roles in regulating cell cycle progression, differentiation, and stem cell maintenance largely through targeting a broad range of oncogenic substrates for proteasome-dependent degradation. The identification of an increasing number of FBW7 substrates for ubiquitination, and intensive in vitro and in vivo studies have revealed a network of signaling components controlled by FBW7 that contributes to metabolic regulation as well as its tumor suppressor role. Here we mainly focus on recent findings that highlight a critical role for FBW7 in cancer and metabolism.
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Abstract
Cellular lipid metabolism and homeostasis are controlled by sterol regulatory-element binding proteins (SREBPs). In addition to performing canonical functions in the transcriptional regulation of genes involved in the biosynthesis and uptake of lipids, genome-wide system analyses have revealed that these versatile transcription factors act as important nodes of convergence and divergence within biological signalling networks. Thus, they are involved in myriad physiological and pathophysiological processes, highlighting the importance of lipid metabolism in biology. Changes in cell metabolism and growth are reciprocally linked through SREBPs. Anabolic and growth signalling pathways branch off and connect to multiple steps of SREBP activation and form complex regulatory networks. In addition, SREBPs are implicated in numerous pathogenic processes such as endoplasmic reticulum stress, inflammation, autophagy and apoptosis, and in this way, they contribute to obesity, dyslipidaemia, diabetes mellitus, nonalcoholic fatty liver disease, nonalcoholic steatohepatitis, chronic kidney disease, neurodegenerative diseases and cancers. This Review aims to provide a comprehensive understanding of the role of SREBPs in physiology and pathophysiology at the cell, organ and organism levels.
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Affiliation(s)
- Hitoshi Shimano
- Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
- Life Science Center, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba 305-8577, Japan
- AMED-CREST, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo 100-0004, Japan
| | - Ryuichiro Sato
- AMED-CREST, Japan Agency for Medical Research and Development, Chiyoda-ku, Tokyo 100-0004, Japan
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan
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Mohamed A, Viveiros A, Williams K, Posse de Chaves E. Aβ inhibits SREBP-2 activation through Akt inhibition. J Lipid Res 2017; 59:1-13. [PMID: 29122977 PMCID: PMC5748492 DOI: 10.1194/jlr.m076703] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 10/21/2017] [Indexed: 12/20/2022] Open
Abstract
We previously demonstrated that oligomeric amyloid β42 (oAβ42) inhibits the mevalonate pathway impairing cholesterol synthesis and protein prenylation. Enzymes of the mevalonate pathway are regulated by the transcription factor SREBP-2. Here, we show that in several neuronal types challenged with oAβ42, SREBP-2 activation is reduced. Moreover, SREBP-2 activation is also decreased in the brain cortex of the Alzheimer's disease (AD) mouse model, TgCRND8, suggesting that SREBP-2 may be affected in vivo early in the disease. We demonstrate that oAβ42 does not affect enzymatic cleavage of SREBP-2 per se, but may impair SREBP-2 transport from the endoplasmic reticulum (ER) to the Golgi. Trafficking of SREBP-2 from the ER to the Golgi requires protein kinase B (Akt) activation. oAβ42 significantly reduces Akt phosphorylation and this decrease is responsible for the decline in SREBP-2 activation. Overexpression of constitutively active Akt prevents the effect of oAβ42 on SREBP-2 and the downstream inhibition of cholesterol synthesis and protein prenylation. Our work provides a novel mechanistic link between Aβ and the mevalonate pathway, which will impact the views on issues related to cholesterol, isoprenoids, and statins in AD. We also identify SREBP-2 as an indirect target of Akt in neurons, which may play a role in the cross-talk between AD and diabetes.
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Affiliation(s)
- Amany Mohamed
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Anissa Viveiros
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Kathleen Williams
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Elena Posse de Chaves
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
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Kang MJ, Kwon EB, Yuk HJ, Ryu HW, Kim SY, Lee MK, Moon DO, Lee SU, Oh SR, Lee HS, Kim MO. Tripterygium regelii decreases the biosynthesis of triacylglycerol and cholesterol in HepG2 cells. Biosci Biotechnol Biochem 2017; 81:2285-2291. [PMID: 29090619 DOI: 10.1080/09168451.2017.1390392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In the course of screening to find a plant material decreasing the activity of triacylglycerol and cholesterol, we identified Tripterygium regelii (TR). The methanol extract of TR leaves (TR-LM) was shown to reduce the intracellular lipid contents consisting of triacylglycerol (TG) and cholesterol in HepG2 cells. TR-LM also downregulated the mRNA and protein expression of the lipogenic genes such as SREBP-1 and its target enzymes. Consequently, TR-LM reduced the TG biosynthesis in HepG2 cells. In addition, TR-LM decreased SREBP2 and its target enzyme HMG-CoA reductase, which is involved in cholesterol synthesis. In this study, we evaluated that TR-LM attenuated cellular lipid contents through the suppression of de novo TG and cholesterol biosynthesis in HepG2 cells. All these taken together, TR-LM could be beneficial in regulating lipid metabolism and useful preventing the hyperlipidemia and its complications, in that liver is a crucial tissue for the secretion of serum lipids.
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Affiliation(s)
- Myung-Ji Kang
- a Korea Research Institute of Bioscience and Biotechnology (KRIBB) , Cheongju , Republic of Korea.,b College of Pharmacy , Chungbuk National University , Cheongju , Republic of Korea
| | - Eun-Bin Kwon
- a Korea Research Institute of Bioscience and Biotechnology (KRIBB) , Cheongju , Republic of Korea.,b College of Pharmacy , Chungbuk National University , Cheongju , Republic of Korea
| | - Heung Joo Yuk
- a Korea Research Institute of Bioscience and Biotechnology (KRIBB) , Cheongju , Republic of Korea
| | - Hyung Won Ryu
- a Korea Research Institute of Bioscience and Biotechnology (KRIBB) , Cheongju , Republic of Korea
| | - Soo-Yeon Kim
- a Korea Research Institute of Bioscience and Biotechnology (KRIBB) , Cheongju , Republic of Korea.,b College of Pharmacy , Chungbuk National University , Cheongju , Republic of Korea
| | - Mi-Kyeong Lee
- b College of Pharmacy , Chungbuk National University , Cheongju , Republic of Korea
| | - Dong-Oh Moon
- c Department of Biology Education , Daegu University , Gyeongsan-si , Republic of Korea
| | - Su Ui Lee
- a Korea Research Institute of Bioscience and Biotechnology (KRIBB) , Cheongju , Republic of Korea
| | - Sei-Ryang Oh
- a Korea Research Institute of Bioscience and Biotechnology (KRIBB) , Cheongju , Republic of Korea
| | - Hyun-Sun Lee
- a Korea Research Institute of Bioscience and Biotechnology (KRIBB) , Cheongju , Republic of Korea
| | - Mun-Ock Kim
- a Korea Research Institute of Bioscience and Biotechnology (KRIBB) , Cheongju , Republic of Korea
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Harada N, Okuyama M, Yoshikatsu A, Yamamoto H, Ishiwata S, Hamada C, Hirose T, Shono M, Kuroda M, Tsutsumi R, Takeo J, Taketani Y, Nakaya Y, Sakaue H. Endoplasmic Reticulum Stress in Mice Increases Hepatic Expression of Genes Carrying a Premature Termination Codon via a Nutritional Status‐Independent GRP78‐Dependent Mechanism. J Cell Biochem 2017; 118:3810-3824. [DOI: 10.1002/jcb.26031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 04/04/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Nagakatsu Harada
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Maiko Okuyama
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Aya Yoshikatsu
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Hironori Yamamoto
- Faculty of Human LifeDepartment of Health and NutritionJin‐ai University3‐1‐1 Ohde‐choEchizen City915‐8586Japan
| | - Saori Ishiwata
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Chikako Hamada
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Tomoyo Hirose
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Masayuki Shono
- Support Center for Advanced Medical SciencesInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Masashi Kuroda
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Rie Tsutsumi
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Jiro Takeo
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
- Central Research LaboratoryNippon Suisan Kaisha32‐3 Nanakuni 1 ChomeHachiojiTokyo192‐0991Japan
| | - Yutaka Taketani
- Department of Clinical Nutrition and Food ManagementInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Yutaka Nakaya
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
| | - Hiroshi Sakaue
- Department of Nutrition and MetabolismInstitute of Biomedical SciencesTokushima University Graduate School3‐18‐15, Kuramoto‐choTokushima City770‐8503Japan
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Jump DB, Botolin D, Wang Y, Xu J, Christian B. Fatty acids and gene transcription. SCANDINAVIAN JOURNAL OF FOOD & NUTRITION 2016. [DOI: 10.1080/17482970601069318] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Donald B. Jump
- Departments of Physiology, Biochemistry and Molecular BiologyMichigan State UniversityMichiganUSA
| | - Daniela Botolin
- Departments of Physiology, Biochemistry and Molecular BiologyMichigan State UniversityMichiganUSA
| | - Yun Wang
- Departments of Physiology, Biochemistry and Molecular BiologyMichigan State UniversityMichiganUSA
| | - Jinghua Xu
- Departments of Physiology, Biochemistry and Molecular BiologyMichigan State UniversityMichiganUSA
| | - Barbara Christian
- Departments of Physiology, Biochemistry and Molecular BiologyMichigan State UniversityMichiganUSA
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Bengoechea-Alonso MT, Ericsson J. The phosphorylation-dependent regulation of nuclear SREBP1 during mitosis links lipid metabolism and cell growth. Cell Cycle 2016; 15:2753-65. [PMID: 27579997 PMCID: PMC5053579 DOI: 10.1080/15384101.2016.1220456] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 07/13/2016] [Accepted: 07/31/2016] [Indexed: 01/02/2023] Open
Abstract
The SREBP transcription factors are major regulators of lipid metabolism. Disturbances in lipid metabolism are at the core of several health issues facing modern society, including cardiovascular disease, obesity and diabetes. In addition, the role of lipid metabolism in cancer cell growth is receiving increased attention. Transcriptionally active SREBP molecules are unstable and rapidly degraded in a phosphorylation-dependent manner by Fbw7, a ubiquitin ligase that targets several cell cycle regulatory proteins for degradation. We have previously demonstrated that active SREBP1 is stabilized during mitosis. We have now delineated the mechanisms involved in the stabilization of SREBP1 in mitotic cells. This process is initiated by the phosphorylation of a specific serine residue in nuclear SREBP1 by the mitotic kinase Cdk1. The phosphorylation of this residue creates a docking site for a separate mitotic kinase, Plk1. Plk1 interacts with nuclear SREBP1 in mitotic cells and phosphorylates a number of residues in the C-terminal domain of the protein, including a threonine residue in close proximity of the Fbw7 docking site in SREBP1. The phosphorylation of these residues by Plk1 blocks the interaction between SREBP1 and Fbw7 and attenuates the Fbw7-dependent degradation of nuclear SREBP1 during cell division. Inactivation of SREBP1 results in a mitotic defect, suggesting that SREBP1 could regulate cell division. We propose that the mitotic phosphorylation and stabilization of nuclear SREBP1 during cell division provides a link between lipid metabolism and cell proliferation. Thus, the current study provides additional support for the emerging hypothesis that SREBP-dependent lipid metabolism may be important for cell growth.
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Affiliation(s)
| | - Johan Ericsson
- University College Dublin, School of Medicine and Medical Science, UCD Conway Institute, Dublin, Ireland
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Intracellular cholesterol transport proteins: roles in health and disease. Clin Sci (Lond) 2016; 130:1843-59. [DOI: 10.1042/cs20160339] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 07/12/2016] [Indexed: 12/13/2022]
Abstract
Effective cholesterol homoeostasis is essential in maintaining cellular function, and this is achieved by a network of lipid-responsive nuclear transcription factors, and enzymes, receptors and transporters subject to post-transcriptional and post-translational regulation, whereas loss of these elegant, tightly regulated homoeostatic responses is integral to disease pathologies. Recent data suggest that sterol-binding sensors, exchangers and transporters contribute to regulation of cellular cholesterol homoeostasis and that genetic overexpression or deletion, or mutations, in a number of these proteins are linked with diseases, including atherosclerosis, dyslipidaemia, diabetes, congenital lipoid adrenal hyperplasia, cancer, autosomal dominant hearing loss and male infertility. This review focuses on current evidence exploring the function of members of the ‘START’ (steroidogenic acute regulatory protein-related lipid transfer) and ‘ORP’ (oxysterol-binding protein-related proteins) families of sterol-binding proteins in sterol homoeostasis in eukaryotic cells, and the evidence that they represent valid therapeutic targets to alleviate human disease.
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Aylon Y, Oren M. The Hippo pathway, p53 and cholesterol. Cell Cycle 2016; 15:2248-55. [PMID: 27419353 PMCID: PMC5004696 DOI: 10.1080/15384101.2016.1207840] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 06/19/2016] [Accepted: 06/26/2016] [Indexed: 02/06/2023] Open
Abstract
ASBTRACT Increased rates of cholesterol and lipid synthesis have long been recognized as important aspects of the metabolic rewiring that occurs during cancerous transformation. Many genes encoding enzymes involved in cholesterol and fatty acid biogenesis are transcriptional targets of the sterol regulatory element-binding proteins (SREBPs). The SREBPs act as a hub for metabolic and proliferation-related signals; their activity is the focus of a tug-of-war between tumor suppressors, who generally inhibit SREBP function, and oncogenes, who often promote, and rely on, SREBP activity. The Hippo pathway plays a central role in coordinating cell proliferation and organ size, whereas p53 is a crucial tumor suppressor that maintains metabolic homeostasis and orchestrates cellular stress responses. Together, the Hippo and p53 signaling pathways cooperate on multiple levels to fine-tune SREPB activity and regulate cholesterol/lipid levels. Cholesterol biosynthesis inhibitors such as statins are appealing conceptually, but have yet to show an indisputable effect on cancer development. Fortunately, the complex regulation surrounding the Hippo-p53-SREBP network potentially provides a broad interface for additional novel cancer-targeting interventions.
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Affiliation(s)
- Yael Aylon
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel
| | - Moshe Oren
- Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot, Israel
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Chen H, Yuan R, Zhang Y, Zhang X, Chen L, Zhou X, Yuan Z, Nie Y, Li M, Mo D, Chen Y. ATF4 regulates SREBP1c expression to control fatty acids synthesis in 3T3-L1 adipocytes differentiation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1459-1469. [PMID: 27452504 DOI: 10.1016/j.bbagrm.2016.07.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/07/2016] [Accepted: 07/20/2016] [Indexed: 11/26/2022]
Abstract
Activating transcription factor 4 (ATF4), which is highly expressed in 3T3-L1 adipocytes after adipogenic induction, is essential for adipocytes differentiation. ATF4 also plays a vital role in regulating fatty acids biosynthesis, whereas the detailed mechanism of this process is still unclear. Here we demonstrated that siRNA-based ATF4 depletion in 3T3-L1 adipocytes significantly reduced the accumulation of fatty acids and triglycerides. Moreover, SREBP1c protein, which is an important transcription factor of lipogenesis, appreciably decreased while Srebp1c mRNA increased. Then we identified that ATF4 could maintain SREBP1c protein stability by directly activating the expression of USP7 which deubiquitinates SREBP1c and increases its protein content in cell. Besides, USP7 could restore the synthesis of fatty acids and triglycerides in the absence of ATF4. On the other hand, we found that ATF4 might inhibit the transcription of Srebp1c through TRB3, which is repressed by IBMX and DEX during early adipogenesis. Thus, our data indicate that ATF4 regulates SREBP1c expression to control fatty acids synthesis.
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Affiliation(s)
- Hu Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Renqiang Yuan
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Ying Zhang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xumeng Zhang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Luxi Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xingyu Zhou
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zhuning Yuan
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yaping Nie
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Ming Li
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Delin Mo
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
| | - Yaosheng Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
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Danesi F, Govoni M, D'Antuono LF, Bordoni A. The molecular mechanism of the cholesterol-lowering effect of dill and kale: The influence of the food matrix components. Electrophoresis 2016; 37:1805-13. [PMID: 27028988 PMCID: PMC5215634 DOI: 10.1002/elps.201600033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 03/09/2016] [Accepted: 03/18/2016] [Indexed: 12/22/2022]
Abstract
Foods are complex matrices containing many different compounds, all of which contribute to the overall effect of the food itself, although they have different mechanisms of action. While evaluating the effect of bioactive compounds, it is important to consider that the use of a single compound can hide the effects of the other molecules that can act synergistically or antagonistically in the same food. The aim of the present study was to evaluate the influence of food matrix components by comparing two edible plants (dill and kale) with cholesterol-lowering potential and similar contents of their most representative bioactive, quercetin. The molecular effects of the extracts were evaluated in HepG2 cells by measuring the expression of sterol-regulatory element-binding proteins (SREBPs), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and low density lipoprotein receptor (LDLR) at the mRNA and protein level. The results reported here show that both extracts reduced the cellular cholesterol level with a similar trend and magnitude. It is conceivable that the slightly different results are due to the diverse composition of minor bioactive compounds, indicating that only by considering food as a whole is it possible to understand the complex relationship between food, nutrition, and health in a foodomics vision.
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Affiliation(s)
- Francesca Danesi
- Department of Agri-Food Science and Technology (DISTAL), University of Bologna, Cesena, FC, Italy
| | - Marco Govoni
- BioEngLab, Health Science and Technology - Interdepartmental Center for Industrial Research (HST-CIRI), University of Bologna, Ozzano dell'Emilia BO, Italy
| | - Luigi Filippo D'Antuono
- Department of Agri-Food Science and Technology (DISTAL), University of Bologna, Cesena, FC, Italy
| | - Alessandra Bordoni
- Department of Agri-Food Science and Technology (DISTAL), University of Bologna, Cesena, FC, Italy
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Bawazeer NA, Choudhry H, Zamzami MA, Abdulaal WH, Middleton B, Moselhy SS. Role of hesperetin in LDL-receptor expression in hepatoma HepG2 cells. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2016; 16:182. [PMID: 27349523 PMCID: PMC4924268 DOI: 10.1186/s12906-016-1165-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2015] [Accepted: 06/15/2016] [Indexed: 11/10/2022]
Abstract
BACKGROUND High plasma concentration of low-density lipoprotein cholesterol (LDL-c) plays a significant role in the incidence of atherosclerosis and coronary heart diseases. The aim of this study was to investigate the mechanism by which the citrus flavonoid, hesperetin, regulates the LDL receptor (LDLr) gene in the human liver using the human hepatoma cell line, HepG2. METHODS Luciferase reporter gene assays were performed (in the absence of lipoprotein) to measure the activity of the LDLr promoter and the promoters of the sterol regulatory element binding protein (SREBP) transcription factors that control the LDLr promoter. RESULTS Only SREBP-1 promoter activity was significantly increased 4 h after exposure to 200 μM hesperetin. However, after 24 h incubation with 200 μM hesperetin, the activities of all the promoter-constructs, SREBP-1a, -1c, -2 and LDLr, were significantly increased. The effects of 200 μM hesperetin on elevating LDLr mRNA levels were possibly due to regulation of LDLr gene transcription by SREBP-la and SREBP-2. CONCLUSIONS We conclude that 200 μM hesperetin was likely to have stimulated LDLr gene expression in human hepatoma HepG2 cells via increased phosphorylation of PI3K andERK1/2, which increased SREBP-1a and SREBP-2 mRNA levels and enhanced the maturation of the encoded proteins. This may lead to lower plasma LDL cholesterol; therefore, diets supplemented with hesperidin might provide cardio-protective effects and reduce mortality and morbidity from coronary heart diseases.
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Affiliation(s)
- Nora A Bawazeer
- Department of Home Economics, Taif University, Taif, Saudi Arabia
| | - Hani Choudhry
- Department of Biochemistry, Faculty of Science, Cancer and mutagensis unit, Center of Innovation in Personalized Medicine, King Fahd Center for medical Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mazin A Zamzami
- Department of Biochemistry, Cancer and mutagensis Unit, King Fahad Medical Research Center, KingAbdulaziz University, Jeddah, Saudi Arabia
| | - Wesam H Abdulaal
- Department of Biochemistry, Cancer and mutagensis Unit, King Fahad Medical Research Center, KingAbdulaziz University, Jeddah, Saudi Arabia
| | - Bruce Middleton
- Department of Biochemistry, Medical School, Nottingham University, Nottingham, UK
| | - Said S Moselhy
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
- Department of Biochemistry, Faculty of Science, Ain shams University, Cairo, Egypt.
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Tong X, Li P, Zhang D, VanDommelen K, Gupta N, Rui L, Omary MB, Yin L. E4BP4 is an insulin-induced stabilizer of nuclear SREBP-1c and promotes SREBP-1c-mediated lipogenesis. J Lipid Res 2016; 57:1219-30. [PMID: 27252523 DOI: 10.1194/jlr.m067181] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Indexed: 12/16/2022] Open
Abstract
Upon food intake, insulin stimulates de novo lipogenesis (DNL) in hepatocytes via the AKT-mTORC1-sterol regulatory element-binding protein (SREBP)-1c pathway. How insulin maintains the maximal SREBP-1c activities during the entire feeding state remains elusive. We previously reported that insulin induced b-ZIP transcription factor, E4-binding protein 4 (E4BP4), in hepatocytes. In the current study, we show that insulin injection increases hepatic E4bp4 expression by activating the AKT-mTORC1-SREBP-1c pathway in hepatocytes. E4bp4-deficient hepatocytes not only fail to maintain robust DNL but also become resistant to SREBP-1c-induced lipogenesis. In vivo, acute depletion of E4bp4 in the liver by adenoviral shRNA reduces the expression of lipogenic enzymes and results in reduced levels of serum triglycerides and cholesterol during the postprandial phase. In hepatocytes, E4BP4 interacts with nuclear SREBP-1c to preserve its acetylation, and subsequently protects it from ubiquitination-dependent degradation. In conclusion, the current studies uncover a novel positive feedback pathway mediated by E4BP4 to augment SREBP-1c-mediated DNL in the liver during the fed state.
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Affiliation(s)
- Xin Tong
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48019
| | - Pei Li
- Xiangya School of Medicine, Central South University, Changsha 410013, People's Republic of China
| | - Deqiang Zhang
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48019
| | - Kyle VanDommelen
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48019
| | - Neil Gupta
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48019
| | - Liangyou Rui
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48019
| | - M Bishr Omary
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48019
| | - Lei Yin
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48019
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Phorbol 12-myristate 13-acetate promotes nuclear translocation of hepatic steroid response element binding protein-2. Int J Biochem Cell Biol 2016; 75:1-10. [PMID: 27032751 DOI: 10.1016/j.biocel.2016.03.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 03/16/2016] [Accepted: 03/21/2016] [Indexed: 11/22/2022]
Abstract
Sterol regulatory element-binding protein (SREBP)-2 is a pivotal transcriptional factor in cholesterol metabolism. Factors interfering with the proper functioning of SREBP-2 potentially alter plasma lipid profiles. Phorbol 12-myristate 13-acetate (PMA), which is a common protein kinase C (PKC) activator, was shown to promote the post-translational processing and nuclear translocation of SREBP-2 in hepatic cells in the current study. Following SREBP-2 translocation, the transcripts of its target genes HMGCR and LDLR were upregulated as demonstrated by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Electrophoretic mobility shift assays (EMSA) also demonstrated an induced DNA-binding activity on the sterol response element (SRE) domain under PMA treatment. The increase of activated Srebp-2 without the concurrent induced mRNA expression was also observed in an animal model. As the expression of SREBP-2 was not increased by PMA, the activation of PKC was the focus of investigation. Specific PKC isozyme inhibition and overexpression supported that PKCβ was responsible for the promoting effect. Further studies showed that the mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinases (JNK), but not 5' adenosine monophosphate-activated protein kinase (AMPK), were the possible downstream signaling proteins of PKCβ. In conclusion, this study illustrated that PKCβ increased SREBP-2 nuclear translocation in a pathway mediated by MEK/ERK and JNK, rather than the one dictated by AMPK. These results revealed a novel signaling target of PKCβ in the liver cells.
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Zhang Y, Ma KL, Ruan XZ, Liu BC. Dysregulation of the Low-Density Lipoprotein Receptor Pathway Is Involved in Lipid Disorder-Mediated Organ Injury. Int J Biol Sci 2016; 12:569-79. [PMID: 27019638 PMCID: PMC4807419 DOI: 10.7150/ijbs.14027] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 02/26/2016] [Indexed: 12/12/2022] Open
Abstract
The low-density lipoprotein receptor (LDLR) pathway is a negative feedback system that plays important roles in the regulation of plasma and intracellular cholesterol homeostasis. To maintain a cholesterol homeostasis, LDLR expression is tightly regulated by sterol regulatory element-binding protein-2 (SREBP-2) and SREBP cleavage-activating protein (SCAP) in transcriptional level and by proprotein convertase subtilisin/kexin type 9 (PCSK9) in posttranscriptional level. The dysregulation of LDLR expression results in abnormal lipid accumulation in cells and tissues, such as vascular smooth muscle cells, hepatic cells, renal mesangial cells, renal tubular cells and podocytes. It has been demonstrated that inflammation, renin-angiotensin system (RAS) activation, and hyperglycemia induce the disruption of LDLR pathway, which might contribute to lipid disorder-mediated organ injury (atherosclerosis, non-alcoholic fatty liver disease, kidney fibrosis, etc). The mammalian target of rapamycin (mTOR) pathway is a critical mediator in the disruption of LDLR pathway caused by pathogenic factors. The mTOR complex1 activation upregulates LDLR expression at the transcriptional and posttranscriptional levels, consequently resulting in lipid deposition. This paper mainly reviews the mechanisms for the dysregulation of LDLR pathway and its roles in lipid disorder-mediated organ injury under various pathogenic conditions. Understanding these mechanisms leading to the abnormality of LDLR expression contributes to find potential new drug targets in lipid disorder-mediated diseases.
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Vallianou I, Hadzopoulou-Cladaras M. Camphene, a Plant Derived Monoterpene, Exerts Its Hypolipidemic Action by Affecting SREBP-1 and MTP Expression. PLoS One 2016; 11:e0147117. [PMID: 26784701 PMCID: PMC4718691 DOI: 10.1371/journal.pone.0147117] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 12/29/2015] [Indexed: 11/18/2022] Open
Abstract
The control of hyperlipidemia plays a central role in cardiovascular disease. Previously, we have shown that camphene, a constituent of mastic gum oil, lowers cholesterol and triglycerides (TG) in the plasma of hyperlipidemic rats without affecting HMG-CoA reductase activity, suggesting that its hypocholesterolemic and hypotriglyceridemic effects are associated with a mechanism of action different than that of statins. In the present study, we examine the mechanism by which camphene exerts its hypolipidemic action. We evaluated the effect of camphene on the de novo synthesis of cholesterol and TG from [14C]-acetate in HepG2 cells, along with the statin mevinolin. Camphene inhibited the biosynthesis of cholesterol in a concentration-dependent manner, and a maximal inhibition of 39% was observed at 100 μM while mevinolin nearly abolished cholesterol biosynthesis. Moreover, treatment with camphene reduced TG by 34% and increased apolipoprotein AI expression. In contrast, mevinolin increased TG by 26% and had a modest effect on apolipoprotein AI expression. To evaluate the mode of action of camphene, we examined its effects on the expression of SREBP-1, which affects TG biosynthesis and SREBP-2, which mostly affects sterol synthesis. Interestingly, camphene increased the nuclear translocation of the mature form of SREBP-1 while mevinolin was found to increase the amount of the mature form of SREBP-2. The effect of camphene is most likely regulated through SREBP-1 by affecting MTP levels in response to a decrease in the intracellular cholesterol. We propose that camphene upregulates SREBP-1 expression and MTP inhibition is likely to be a probable mechanism whereby camphene exerts its hypolipidemic effect.
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Affiliation(s)
- Ioanna Vallianou
- Department of Genetics, Development and Molecular Biology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece
| | - Margarita Hadzopoulou-Cladaras
- Department of Genetics, Development and Molecular Biology, School of Biology, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece
- * E-mail:
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Glycogen synthase kinase-3-mediated phosphorylation of serine 73 targets sterol response element binding protein-1c (SREBP-1c) for proteasomal degradation. Biosci Rep 2015; 36:e00284. [PMID: 26589965 PMCID: PMC4718510 DOI: 10.1042/bsr20150234] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 10/30/2015] [Indexed: 01/08/2023] Open
Abstract
We have identified Serine 73 as a novel GSK-3β site on SREBP-1c that alters its affinity for SCAP, and proteasomal degradation. Phosphorylation of Serine 73 by GSK-3β during starvation (insulin-depleted stat) may lead to lower levels of SREBP-1c; conversely, de-phosphorylation of this site may be involved in stabilizing SREBP-1c by insulin (by blocking GSK-3β action). A functional role of this site needs to be corroborated in vivo. Sterol regulatory element binding protein-1c (SREBP-1c) is a key transcription factor that regulates genes involved in the de novo lipid synthesis and glycolysis pathways. The structure, turnover and transactivation potential of SREBP-1c are regulated by macronutrients and hormones via a cascade of signalling kinases. Using MS, we have identified serine 73 as a novel glycogen synthase kinase-3 (GSK-3) phosphorylation site in the rat SREBP-1c purified from McA-RH7777 hepatoma cells. Our site-specific mutagenesis strategy revealed that the turnover of SREBP-1c, containing wild type, phospho-null (serine to alanine) or phospho-mimetic (serine to aspartic acid) substitutions, was differentially regulated. We show that the S73D mutant of pSREBP-1c, that mimicked a state of constitutive phosphorylation, dissociated from the SREBP-1c–SCAP complex more readily and underwent GSK-3-dependent proteasomal degradation via SCFFbw7 ubiquitin ligase pathway. Pharmacologic inhibition of GSK-3 or knockdown of GSK-3 by siRNA prevented accelerated degradation of SREBP-1c. As demonstrated by MS, SREBP-1c was phosphorylated in vitro by GSK-3β at serine 73. Phosphorylation of serine 73 also occurs in the intact liver. We propose that GSK-3-mediated phosphorylation of serine 73 in the rat SREBP-1c and its concomitant destabilization represents a novel mechanism involved in the inhibition of de novo lipid synthesis in the liver.
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Wong TY, Lin SM, Leung LK. The Flavone Luteolin Suppresses SREBP-2 Expression and Post-Translational Activation in Hepatic Cells. PLoS One 2015; 10:e0135637. [PMID: 26302339 PMCID: PMC4547722 DOI: 10.1371/journal.pone.0135637] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 07/24/2015] [Indexed: 11/18/2022] Open
Abstract
High blood cholesterol has been associated with cardiovascular diseases. The enzyme HMG CoA reductase (HMGCR) is responsible for cholesterol synthesis, and inhibitors of this enzyme (statins) have been used clinically to control blood cholesterol. Sterol regulatory element binding protein (SREBP) -2 is a key transcription factor in cholesterol metabolism, and HMGCR is a target gene of SREBP-2. Attenuating SREBP-2 activity could potentially minimize the expression of HMGCR. Luteolin is a flavone that is commonly detected in plant foods. In the present study, Luteolin suppressed the expression of SREBP-2 at concentrations as low as 1 μM in the hepatic cell lines WRL and HepG2. This flavone also prevented the nuclear translocation of SREBP-2. Post-translational processing of SREBP-2 protein was required for nuclear translocation. Luteolin partially blocked this activation route through increased AMP kinase (AMPK) activation. At the transcriptional level, the mRNA and protein expression of SREBP-2 were reduced through luteolin. A reporter gene assay also verified that the transcription of SREBF2 was weakened in response to this flavone. The reduced expression and protein processing of SREBP-2 resulted in decreased nuclear translocation. Thus, the transcription of HMGCR was also decreased after luteolin treatment. In summary, the results of the present study showed that luteolin modulates HMGCR transcription by decreasing the expression and nuclear translocation of SREBP-2.
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Affiliation(s)
- Tsz Yan Wong
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong S.A.R., People's Republic of China
| | - Shu-mei Lin
- Dept. of Food Science, National Chiayi University, Chiayi City, Taiwan, (R.O.C.)
| | - Lai K. Leung
- Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong S.A.R., People's Republic of China
- Biochemistry Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong S.A.R., People's Republic of China
- * E-mail:
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Miyata S, Inoue J, Shimizu M, Sato R. Xanthohumol Improves Diet-induced Obesity and Fatty Liver by Suppressing Sterol Regulatory Element-binding Protein (SREBP) Activation. J Biol Chem 2015; 290:20565-79. [PMID: 26140926 DOI: 10.1074/jbc.m115.656975] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Indexed: 02/02/2023] Open
Abstract
Sterol regulatory element-binding proteins (SREBPs) are key transcription factors that stimulate the expression of genes involved in fatty acid and cholesterol biosynthesis. Here, we demonstrate that a prenylated flavonoid in hops, xanthohumol (XN), is a novel SREBP inactivator that reduces the de novo synthesis of fatty acid and cholesterol. XN independently suppressed the maturation of SREBPs of insulin-induced genes in a manner different from sterols. Our results suggest that XN impairs the endoplasmic reticulum-to-Golgi translocation of the SREBP cleavage-activating protein (SCAP)-SREBP complex by binding to Sec23/24 and blocking SCAP/SREBP incorporation into common coated protein II vesicles. Furthermore, in diet-induced obese mice, dietary XN suppressed SREBP-1 target gene expression in the liver accompanied by a reduction of the mature form of hepatic SREBP-1, and it inhibited the development of obesity and hepatic steatosis. Altogether, our data suggest that XN attenuates the function of SREBP-1 by repressing its maturation and that it has the potential of becoming a nutraceutical food or pharmacological agent for improving metabolic syndrome.
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Affiliation(s)
- Shingo Miyata
- From the Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan
| | - Jun Inoue
- From the Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan
| | - Makoto Shimizu
- From the Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan
| | - Ryuichiro Sato
- From the Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan
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Barbosa S, Carreira S, Bailey D, Abaitua F, O'Hare P. Phosphorylation and SCF-mediated degradation regulate CREB-H transcription of metabolic targets. Mol Biol Cell 2015; 26:2939-54. [PMID: 26108621 PMCID: PMC4571331 DOI: 10.1091/mbc.e15-04-0247] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 06/15/2015] [Indexed: 12/12/2022] Open
Abstract
CREB‑H, an endoplasmic reticulum-anchored transcription factor, plays a key role in regulating secretion and in metabolic and inflammatory pathways, but how its activity is modulated remains unclear. We examined processing of the nuclear active form and identified a motif around S87-S90 with homology to DSG-type phosphodegrons. We show that this region is subject to multiple phosphorylations, which regulate CREB-H stability by targeting it to the SCF(Fbw1a) E3 ubiquitin ligase. Data from phosphatase treatment, use of phosophospecific antibody, and substitution of serine residues demonstrate phosphorylation of candidate serines in the region, with the core S87/S90 motif representing a critical determinant promoting proteasome-mediated degradation. Candidate kinases CKII and GSK-3b phosphorylate CREB-H in vitro with specificities for different serines. Prior phosphorylation with GSK-3 at one or more of the adjacent serines substantially increases S87/S90-dependent phosphorylation by CKII. In vivo expression of a dominant-negative Cul1 enhances steady-state levels of CREB‑H, an effect augmented by Fbw1a. CREB-H directly interacts with Fbw1a in a phosphorylation-dependent manner. Finally, mutations within the phosphodegron, when incorporated into the full-length protein, result in increased levels of constitutively cleaved nuclear protein and increased transcription and secretion of a key endogenous target gene, apolipoprotein A IV.
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Affiliation(s)
- Sónia Barbosa
- Department of Medicine, Imperial College, London W2 1PG, United Kingdom
| | - Suzanne Carreira
- Department of Medicine, Imperial College, London W2 1PG, United Kingdom
| | - Daniel Bailey
- Health Protection Agency, Porton Down, Salisbury SP4 0JG, United Kingdom
| | - Fernando Abaitua
- Department of Medicine, Imperial College, London W2 1PG, United Kingdom
| | - Peter O'Hare
- Department of Medicine, Imperial College, London W2 1PG, United Kingdom
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The flavone apigenin blocks nuclear translocation of sterol regulatory element-binding protein-2 in the hepatic cells WRL-68. Br J Nutr 2015; 113:1844-52. [DOI: 10.1017/s0007114515001312] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Sterol regulatory element-binding protein-2 (SREBP-2) is a pivotal transcriptional factor in cholesterol metabolism. Factors interfering with the proper functioning of SREBP-2 potentially alter plasma lipid concentrations. Consuming fruits and vegetables is associated with beneficial plasma lipid profile. The mechanism by which plant foods induce desirable lipid changes remains unclear. Apigenin, a common plant food flavonoid, was shown to modulate the nuclear translocation of SREBP-2 in the hepatic cells WRL-68 in the present study. The processing of SREBP-2 protein occurred after translation, and apigenin blocked this activation route. Further examination indicated that AMP-activated protein kinase (AMPK) was activated by the flavone, and co-administrating the AMPK-specific inhibitor compound C could release the blockage. Reporter gene assay revealed that the transactivation of sterol responsive element (SRE)-containing 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) promoter was suppressed by the flavone. Similarly, electromobility shift assay result also demonstrated a reduced DNA-binding activity on the SRE domain under the same treatment. The reduced transactivity and DNA-binding activity could be attributed to a decreased amount of SREBP-2 translocating from cytosol to nucleus as depicted by confocal microscopy. Quantitative RT-PCR assay demonstrated that the transcription of HMGCR followed the same pattern of SREBP-2 translocation. In summary, the present study showed that apigenin prevented SREBP-2 translocation and reduced the downstream gene HMGCR transcription. The minimum effective dosage should be achievable in the form of functional food consumption or dietary supplementation.
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