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Kim HY, Jang HJ, Muthamil S, Shin UC, Lyu JH, Kim SW, Go Y, Park SH, Lee HG, Park JH. Novel insights into regulators and functional modulators of adipogenesis. Biomed Pharmacother 2024; 177:117073. [PMID: 38981239 DOI: 10.1016/j.biopha.2024.117073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 06/27/2024] [Accepted: 06/29/2024] [Indexed: 07/11/2024] Open
Abstract
Adipogenesis is a process that differentiates new adipocytes from precursor cells and is tightly regulated by several factors, including many transcription factors and various post-translational modifications. Recently, new roles of adipogenesis have been suggested in various diseases. However, the molecular mechanisms and functional modulation of these adipogenic genes remain poorly understood. This review summarizes the regulatory factors and modulators of adipogenesis and discusses future research directions to identify novel mechanisms regulating adipogenesis and the effects of adipogenic regulators in pathological conditions. The master adipogenic transcriptional factors PPARγ and C/EBPα were identified along with other crucial regulatory factors such as SREBP, Kroxs, STAT5, Wnt, FOXO1, SWI/SNF, KLFs, and PARPs. These transcriptional factors regulate adipogenesis through specific mechanisms, depending on the adipogenic stage. However, further studies related to the in vivo role of newly discovered adipogenic regulators and their function in various diseases are needed to develop new potent therapeutic strategies for metabolic diseases and cancer.
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Affiliation(s)
- Hyun-Yong Kim
- Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, Naju, Jeollanam-do 58245, Republic of Korea; New Drug Development Center, Osong Medical Innovation Foundation, 123, Osongsaengmyeong-ro, Osong-eup, Heungdeok-gu, Cheongju-si, Chungcheongbuk-do 28160, Republic of Korea.
| | - Hyun-Jun Jang
- Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, Naju, Jeollanam-do 58245, Republic of Korea; Research Group of Personalized Diet, Korea Food Research Institute, Wanju-gun, Jeollabuk-do 55365, Republic of Korea.
| | - Subramanian Muthamil
- Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, Naju, Jeollanam-do 58245, Republic of Korea.
| | - Ung Cheol Shin
- Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, Naju, Jeollanam-do 58245, Republic of Korea.
| | - Ji-Hyo Lyu
- Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, Naju, Jeollanam-do 58245, Republic of Korea.
| | - Seon-Wook Kim
- Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, Naju, Jeollanam-do 58245, Republic of Korea.
| | - Younghoon Go
- Korean Medicine (KM)-application Center, Korea Institute of Oriental Medicine, Daegu 41062, Republic of Korea.
| | - Seong-Hoon Park
- Genetic and Epigenetic Toxicology Research Group, Korea Institute of Toxicology, Daejeon 34141, Republic of Korea.
| | - Hee Gu Lee
- Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Republic of Korea.
| | - Jun Hong Park
- Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, Naju, Jeollanam-do 58245, Republic of Korea; University of Science & Technology (UST), KIOM campus, Korean Convergence Medicine Major, Daejeon 34054, Republic of Korea.
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Agrawal S, Buyan A, Severin J, Koido M, Alam T, Abugessaisa I, Chang HY, Dostie J, Itoh M, Kere J, Kondo N, Li Y, Makeev VJ, Mendez M, Okazaki Y, Ramilowski JA, Sigorskikh AI, Strug LJ, Yagi K, Yasuzawa K, Yip CW, Hon CC, Hoffman MM, Terao C, Kulakovskiy IV, Kasukawa T, Shin JW, Carninci P, de Hoon MJL. Annotation of nuclear lncRNAs based on chromatin interactions. PLoS One 2024; 19:e0295971. [PMID: 38709794 PMCID: PMC11073715 DOI: 10.1371/journal.pone.0295971] [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: 06/19/2023] [Accepted: 12/02/2023] [Indexed: 05/08/2024] Open
Abstract
The human genome is pervasively transcribed and produces a wide variety of long non-coding RNAs (lncRNAs), constituting the majority of transcripts across human cell types. Some specific nuclear lncRNAs have been shown to be important regulatory components acting locally. As RNA-chromatin interaction and Hi-C chromatin conformation data showed that chromatin interactions of nuclear lncRNAs are determined by the local chromatin 3D conformation, we used Hi-C data to identify potential target genes of lncRNAs. RNA-protein interaction data suggested that nuclear lncRNAs act as scaffolds to recruit regulatory proteins to target promoters and enhancers. Nuclear lncRNAs may therefore play a role in directing regulatory factors to locations spatially close to the lncRNA gene. We provide the analysis results through an interactive visualization web portal at https://fantom.gsc.riken.jp/zenbu/reports/#F6_3D_lncRNA.
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Affiliation(s)
- Saumya Agrawal
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Andrey Buyan
- Autosome.org, Russia
- FANTOM Consortium, Dolgoprudny, Russia
| | - Jessica Severin
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Masaru Koido
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Tanvir Alam
- College of Science and Engineering, Hamad Bin Khalifa University, Doha, Qatar
| | | | - Howard Y. Chang
- Center for Personal Dynamic Regulome, Stanford University, Stanford, California, United States of America
| | - Josée Dostie
- Department of Biochemistry, Rosalind and Morris Goodman Cancer Research Center, McGill University, Montréal, Québec, Canada
| | - Masayoshi Itoh
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- RIKEN Preventive Medicine and Diagnosis Innovation Program, Wako, Japan
| | - Juha Kere
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
- Stem Cells and Metabolism Research Program, University of Helsinki and Folkhälsan Research Center, Helsinki, Finland
| | - Naoto Kondo
- RIKEN Center for Life Science Technologies, Yokohama, Japan
| | - Yunjing Li
- Division of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
| | | | - Mickaël Mendez
- Department of Computer Science, University of Toronto, Toronto, Ontario, Canada
| | - Yasushi Okazaki
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Jordan A. Ramilowski
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- Advanced Medical Research Center, Yokohama City University, Yokohama, Japan
| | | | - Lisa J. Strug
- Division of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
- Department of Computer Science, University of Toronto, Toronto, Ontario, Canada
- Department of Statistical Sciences, University of Toronto, Ontario, Canada
- The Centre for Applied Genomics and Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Ken Yagi
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Kayoko Yasuzawa
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Chi Wai Yip
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Chung Chau Hon
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Michael M. Hoffman
- Department of Computer Science, University of Toronto, Toronto, Ontario, Canada
- Princess Margaret Cancer Centre, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Vector Institute, Toronto, Ontario, Canada
| | - Chikashi Terao
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | | | - Takeya Kasukawa
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Jay W. Shin
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- Genome Institute of Singapore (GIS), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Piero Carninci
- RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- Human Technopole, Milan, Italy
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3
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Song Y, Wei D, Raza SHA, Zhao Y, Jiang C, Song X, Wu H, Wang X, Luoreng Z, Ma Y. Research progress of intramuscular fat formation based on co-culture. Anim Biotechnol 2023; 34:3216-3236. [PMID: 36200856 DOI: 10.1080/10495398.2022.2127410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Intramuscular fat (IMF) is closely related to the meat quality of livestock and poultry. As a new cell culture technique in vitro, cell co-culture has been gradually applied to the related research of IMF formation because it can simulate the changes of microenvironment in vivo during the process of IMF cell formation. In the co-culture model, in addition to studying the effects of skeletal muscle cells on the proliferation and differentiation of IMF, we can also consider the role of many secretion factors in the formation of IMF, thus making the cell research in vitro closer to the real level in vivo. This paper reviewed the generation and origin of IMF, summarized the existing co-culture methods and systems, and discussed the advantages and disadvantages of each method as well as the challenges faced in the establishment of the system, with emphasis on the current status of research on the formation of IMF for human and animal based on co-culture technology.
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Affiliation(s)
- Yaping Song
- School of Agriculture, Ningxia University, Ningxia Yin Chuan, China
- Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia University, Ningxia Yinchuan, China
| | - Dawei Wei
- School of Agriculture, Ningxia University, Ningxia Yin Chuan, China
- Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia University, Ningxia Yinchuan, China
| | | | - Yiang Zhao
- School of Agriculture, Ningxia University, Ningxia Yin Chuan, China
- Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia University, Ningxia Yinchuan, China
| | - Chao Jiang
- School of Agriculture, Ningxia University, Ningxia Yin Chuan, China
- Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia University, Ningxia Yinchuan, China
| | - Xiaoyu Song
- School of Agriculture, Ningxia University, Ningxia Yin Chuan, China
- Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia University, Ningxia Yinchuan, China
| | - Hao Wu
- School of Agriculture, Ningxia University, Ningxia Yin Chuan, China
- Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia University, Ningxia Yinchuan, China
| | - Xingping Wang
- School of Agriculture, Ningxia University, Ningxia Yin Chuan, China
- Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia University, Ningxia Yinchuan, China
| | - Zhuoma Luoreng
- School of Agriculture, Ningxia University, Ningxia Yin Chuan, China
- Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia University, Ningxia Yinchuan, China
| | - Yun Ma
- School of Agriculture, Ningxia University, Ningxia Yin Chuan, China
- Key Laboratory of Ruminant Molecular Cell Breeding, Ningxia University, Ningxia Yinchuan, China
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4
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Zhang Y, Tian Z, Ye H, Sun X, Zhang H, Sun Y, Mao Y, Yang Z, Li M. Emerging functions of circular RNA in the regulation of adipocyte metabolism and obesity. Cell Death Dis 2022; 8:268. [PMID: 35595755 PMCID: PMC9122900 DOI: 10.1038/s41420-022-01062-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 05/04/2022] [Accepted: 05/10/2022] [Indexed: 02/08/2023]
Abstract
As noncoding RNAs, circular RNAs (circRNAs) are covalently enclosed endogenous biomolecules in eukaryotes that have tissue specificity and cell specificity. circRNAs were once considered a rare splicing byproduct. With the development of high-throughput sequencing, it has been confirmed that they are expressed in thousands of mammalian genes. To date, only a few circRNA functions and regulatory mechanisms have been verified. Adipose is the main tissue for body energy storage and energy supply. Adipocyte metabolism is a physiological process involving a series of genes and affects biological activities in the body, such as energy metabolism, immunity, and signal transmission. When adipocyte formation is dysregulated, it will cause a series of diseases, such as atherosclerosis, obesity, fatty liver, and diabetes. In recent years, many noncoding RNAs involved in adipocyte metabolism have been revealed. This review provides a comprehensive overview of the basic structure and biosynthetic mechanism of circRNAs, and further discusses the circRNAs related to adipocyte formation in adipose tissue and liver. Our review will provide a reference for further elucidating the genetic regulation mechanism of circRNAs involved in adipocyte metabolism.
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Affiliation(s)
- Yuanyuan Zhang
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, 225009, Yangzhou, Jiangsu, China.,Key Laboratory of Animal Genetics & Breeding and Molecular Design of Jiangsu province, College of Animal Science and Technology, Yangzhou University, 225009, Yangzhou, Jiangsu, China
| | - Zhichen Tian
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, 225009, Yangzhou, Jiangsu, China.,Key Laboratory of Animal Genetics & Breeding and Molecular Design of Jiangsu province, College of Animal Science and Technology, Yangzhou University, 225009, Yangzhou, Jiangsu, China
| | - Haibo Ye
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, 225009, Yangzhou, Jiangsu, China.,Key Laboratory of Animal Genetics & Breeding and Molecular Design of Jiangsu province, College of Animal Science and Technology, Yangzhou University, 225009, Yangzhou, Jiangsu, China
| | - Xiaomei Sun
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, 225009, Yangzhou, Jiangsu, China.,Key Laboratory of Animal Genetics & Breeding and Molecular Design of Jiangsu province, College of Animal Science and Technology, Yangzhou University, 225009, Yangzhou, Jiangsu, China
| | - Huiming Zhang
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, 225009, Yangzhou, Jiangsu, China.,Key Laboratory of Animal Genetics & Breeding and Molecular Design of Jiangsu province, College of Animal Science and Technology, Yangzhou University, 225009, Yangzhou, Jiangsu, China
| | - Yujia Sun
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, 225009, Yangzhou, Jiangsu, China.,Key Laboratory of Animal Genetics & Breeding and Molecular Design of Jiangsu province, College of Animal Science and Technology, Yangzhou University, 225009, Yangzhou, Jiangsu, China
| | - Yongjiang Mao
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, 225009, Yangzhou, Jiangsu, China.,Key Laboratory of Animal Genetics & Breeding and Molecular Design of Jiangsu province, College of Animal Science and Technology, Yangzhou University, 225009, Yangzhou, Jiangsu, China
| | - Zhangping Yang
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, 225009, Yangzhou, Jiangsu, China. .,Key Laboratory of Animal Genetics & Breeding and Molecular Design of Jiangsu province, College of Animal Science and Technology, Yangzhou University, 225009, Yangzhou, Jiangsu, China.
| | - Mingxun Li
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, 225009, Yangzhou, Jiangsu, China. .,Key Laboratory of Animal Genetics & Breeding and Molecular Design of Jiangsu province, College of Animal Science and Technology, Yangzhou University, 225009, Yangzhou, Jiangsu, China.
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5
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Sultan F, Basu R, Murthy D, Kochar M, Attri KS, Aggarwal A, Kumari P, Dnyane P, Tanwar J, Motiani RK, Singh A, Gadgil C, Bhavesh NS, Singh PK, Natarajan VT, Gokhale RS. Temporal analysis of melanogenesis identifies fatty acid metabolism as key skin pigment regulator. PLoS Biol 2022; 20:e3001634. [PMID: 35584084 PMCID: PMC9116682 DOI: 10.1371/journal.pbio.3001634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 04/19/2022] [Indexed: 11/19/2022] Open
Abstract
Therapeutic methods to modulate skin pigmentation has important implications for skin cancer prevention and for treating cutaneous hyperpigmentary conditions. Towards defining new potential targets, we followed temporal dynamics of melanogenesis using a cell-autonomous pigmentation model. Our study elucidates 3 dominant phases of synchronized metabolic and transcriptional reprogramming. The melanogenic trigger is associated with high MITF levels along with rapid uptake of glucose. The transition to pigmented state is accompanied by increased glucose channelisation to anabolic pathways that support melanosome biogenesis. SREBF1-mediated up-regulation of fatty acid synthesis results in a transient accumulation of lipid droplets and enhancement of fatty acids oxidation through mitochondrial respiration. While this heightened bioenergetic activity is important to sustain melanogenesis, it impairs mitochondria lately, shifting the metabolism towards glycolysis. This recovery phase is accompanied by activation of the NRF2 detoxication pathway. Finally, we show that inhibitors of lipid metabolism can resolve hyperpigmentary conditions in a guinea pig UV-tanning model. Our study reveals rewiring of the metabolic circuit during melanogenesis, and fatty acid metabolism as a potential therapeutic target in a variety of cutaneous diseases manifesting hyperpigmentary phenotype. Temporal analysis of melanogenesis, based on transcriptomic and metabolomic signatures, reveals fatty acid metabolism as a crucial mediator of the transition between pigmentation phases. Inhibitors of the fatty acid pathway could represent a new target for modulating pigmentation.
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Affiliation(s)
- Farina Sultan
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, UP, India
| | - Reelina Basu
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Divya Murthy
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Manisha Kochar
- Immunometabolism Laboratory, National Institute of Immunology, New Delhi, India
| | - Kuldeep S. Attri
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Ayush Aggarwal
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, UP, India
| | - Pooja Kumari
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Pooja Dnyane
- Academy of Scientific and Innovative Research, Ghaziabad, UP, India
- CSIR-National Chemical Laboratory, Pune, Maharashtra, India
| | - Jyoti Tanwar
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, UP, India
- Laboratory of Calciomics and Systemic Pathophysiology, Regional Centre of Biotechnology (RCB), Faridabad, Haryana, India
| | - Rajender K. Motiani
- Laboratory of Calciomics and Systemic Pathophysiology, Regional Centre of Biotechnology (RCB), Faridabad, Haryana, India
| | - Archana Singh
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, UP, India
| | - Chetan Gadgil
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, UP, India
- CSIR-National Chemical Laboratory, Pune, Maharashtra, India
| | - Neel Sarovar Bhavesh
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Pankaj K. Singh
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Vivek T. Natarajan
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, UP, India
- * E-mail: (VTN); (RSG)
| | - Rajesh S. Gokhale
- Immunometabolism Laboratory, National Institute of Immunology, New Delhi, India
- * E-mail: (VTN); (RSG)
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Tyurin-Kuzmin PA, Molchanov AY, Chechekhin VI, Ivanova AM, Kulebyakin KY. Metabolic Regulation of Mammalian Stem Cell Differentiation. BIOCHEMISTRY (MOSCOW) 2020; 85:264-278. [PMID: 32564731 DOI: 10.1134/s0006297920030025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Formation of normal tissue structure, homeostasis maintenance, and tissue damage repair require proliferation and differentiation of stem cells. A distinctive feature of these cells is a unique organization of metabolic pathways, in which contribution of energy production mechanisms to the general cellular metabolism is principally different from that in differentiated cells. Moreover, metabolic changes during differentiation of embryonic and postnatal stem cells have several specific features. The alterations in the stem cell metabolism are not simply consequences of cell differentiation, but also active regulators of this process. Metabolic enzymes and intermediates control and guide the maintenance of stemness, self-renewal, and differentiation of stem cells. The review discusses the patterns and molecular mechanisms of the switch in the metabolism of stem cells during their transition from the pluripotent to differentiated state with the special emphasis on how metabolic processes occurring in the stem cells regulate their functions, ability to differentiate, and the choice of the direction for development.
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Affiliation(s)
- P A Tyurin-Kuzmin
- Lomonosov Moscow State University, Faculty of Medicine, Department of Biochemistry and Molecular Medicine, Moscow, 119991, Russia.
| | - A Yu Molchanov
- Lomonosov Moscow State University, Faculty of Biology, Department of Embryology, Moscow, 119234, Russia
| | - V I Chechekhin
- Lomonosov Moscow State University, Faculty of Medicine, Department of Biochemistry and Molecular Medicine, Moscow, 119991, Russia
| | - A M Ivanova
- Lomonosov Moscow State University, Faculty of Medicine, Department of Biochemistry and Molecular Medicine, Moscow, 119991, Russia
| | - K Yu Kulebyakin
- Lomonosov Moscow State University, Faculty of Medicine, Department of Biochemistry and Molecular Medicine, Moscow, 119991, Russia
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Lee GE, Kim J, Lee JS, Ko J, Lee EJ, Yoon JS. Role of Proprotein Convertase Subtilisin/Kexin Type 9 in the Pathogenesis of Graves' Orbitopathy in Orbital Fibroblasts. Front Endocrinol (Lausanne) 2020; 11:607144. [PMID: 33488522 PMCID: PMC7821242 DOI: 10.3389/fendo.2020.607144] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 11/24/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND The proprotein convertase subtilisin/kexin type 9 (PCSK9) has been implicated in the pathogenesis of inflammatory diseases. We sought to investigate the role of PCSK9 in the pathogenesis of Graves' orbitopathy (GO) and whether it may be a legitimate target for treatment. METHODS The PCSK9 was compared between GO (n=11) and normal subjects (n=7) in orbital tissue explants using quantitative real-time PCR, and in cultured interleukin-1β (IL-1β)-treated fibroblasts using western blot. Western blot was used to identify the effects of PCSK9 inhibition on IL-1β-induced pro-inflammatory cytokines production and signaling molecules expression as well as levels of adipogenic markers and oxidative stress-related proteins. Adipogenic differentiation was identified using Oil Red O staining. The plasma PCSK9 concentrations were compared between patients with GO (n=44) and healthy subjects (n=26) by ELISA. RESULTS The PCSK9 transcript level was higher in GO tissues. The depletion of PCSK9 blunted IL-1β-induced expression of intercellular adhesion molecule 1 (ICAM-1), IL-6, IL-8, and cyclooxygenase-2 (COX-2) in GO and non-GO fibroblasts. The levels of activated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and phosphorylated forms of Akt and p38 were diminished when PCSK9 was suppressed in GO fibroblasts. Decreases in lipid droplets and attenuated levels of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein β (C/EBPβ), and leptin as well as hypoxia-inducible factor 1α (HIF-1α), manganese superoxide dismutase (MnSOD), thioredoxin (Trx), and heme oxygenase-1 (HO-1) were noted when PCSK9 was suppressed during adipocyte differentiation. The plasma PCSK9 level was significantly higher in GO patients and correlated with level of thyrotropin binding inhibitory immunoglobulin (TBII) and the clinical activity score (CAS). CONCLUSIONS PCSK9 plays a significant role in GO. The PCSK9 inhibition attenuated the pro-inflammatory cytokines production, oxidative stress, and fibroblast differentiation into adipocytes. PCSK9 may serve as a therapeutic target and biomarker for GO.
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Affiliation(s)
- Ga Eun Lee
- Yonsei University College of Medicine, Seoul, South Korea
| | - Jinjoo Kim
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea
| | - Jihei Sara Lee
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea
| | - JaeSang Ko
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea
| | - Eun Jig Lee
- Department of Endocrinology, Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea
| | - Jin Sook Yoon
- Department of Ophthalmology, Severance Hospital, Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea
- *Correspondence: Jin Sook Yoon,
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8
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Tung EWY, Peshdary V, Gagné R, Rowan-Carroll A, Yauk CL, Boudreau A, Atlas E. Adipogenic Effects and Gene Expression Profiling of Firemaster® 550 Components in Human Primary Preadipocytes. ENVIRONMENTAL HEALTH PERSPECTIVES 2017; 125:097013. [PMID: 28934090 PMCID: PMC5915190 DOI: 10.1289/ehp1318] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 05/18/2017] [Accepted: 05/23/2017] [Indexed: 05/27/2023]
Abstract
BACKGROUND Exposure to flame retardants has been associated with negative health outcomes including metabolic effects. As polybrominated diphenyl ether flame retardants were pulled from commerce, human exposure to new flame retardants such as Firemaster® 550 (FM550) has increased. Although previous studies in murine systems have shown that FM550 and its main components increase adipogenesis, the effects of FM550 in human models have not been elucidated. OBJECTIVES The objectives of this study were to determine if FM550 and its components are active in human preadipocytes, and to further investigate their mode of action. METHODS Human primary preadipocytes were differentiated in the presence of FM550 and its components. Differentiation was assessed by lipid accumulation and expression of peroxisome proliferator-activated receptor γ (PPARG), fatty acid binding protein (FABP) 4 and lipoprotein lipase (LPL). mRNA was collected for Poly (A) RNA sequencing and was used to identify differentially expressed genes (DEGs). Functional analysis of DEGs was undertaken in Ingenuity Pathway Analysis. RESULTS FM550 triphenyl phosphate (TPP) and isopropylated triphenyl phosphates (IPTP), increased adipogenesis in human primary preadipocytes as assessed by lipid accumulation and mRNA expression of regulators of adipogenesis such as PPARγ, CCAAT enhancer binding protein (C/EBP) α and sterol regulatory element binding protein (SREBP) 1 as well as the adipogenic markers FABP4 LPL and perilipin. Poly (A) RNA sequencing analysis revealed potential modes of action including liver X receptor/retinoid X receptor (LXR/RXR) activation, thyroid receptor (TR)/RXR, protein kinase A, and nuclear receptor subfamily 1 group H members activation. CONCLUSIONS We found that FM550, and two of its components, induced adipogenesis in human primary preadipocytes. Further, using global gene expression analysis we showed that both TPP and IPTP likely exert their effects through PPARG to induce adipogenesis. In addition, IPTP perturbed signaling pathways that were not affected by TPP. https://doi.org/10.1289/EHP1318.
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Affiliation(s)
- Emily W Y Tung
- Environmental Health Science and Research Bureau, Health Canada , Ottawa, Ontario, Canada
| | - Vian Peshdary
- Environmental Health Science and Research Bureau, Health Canada , Ottawa, Ontario, Canada
| | - Remi Gagné
- Environmental Health Science and Research Bureau, Health Canada , Ottawa, Ontario, Canada
| | - Andrea Rowan-Carroll
- Environmental Health Science and Research Bureau, Health Canada , Ottawa, Ontario, Canada
| | - Carole L Yauk
- Environmental Health Science and Research Bureau, Health Canada , Ottawa, Ontario, Canada
| | - Adéle Boudreau
- Environmental Health Science and Research Bureau, Health Canada , Ottawa, Ontario, Canada
| | - Ella Atlas
- Environmental Health Science and Research Bureau, Health Canada , Ottawa, Ontario, Canada
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Saad DY, Soliman MM, Baiomy AA, Yassin MH, El-Sawy HB. Effects of Karela (Bitter Melon; Momordica charantia) on genes of lipids and carbohydrates metabolism in experimental hypercholesterolemia: biochemical, molecular and histopathological study. Altern Ther Health Med 2017. [PMID: 28623919 PMCID: PMC5474009 DOI: 10.1186/s12906-017-1833-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background Hypercholesterolemia is a serious diseases associated with type-2 diabetes, atherosclerosis, cardiovascular disorders and liver diseases. Humans seek for safe herbal medication such as karela (Momordica charantia/bitter melon) to treat such disorders to avoid side effect of pharmacotherapies widely used. Methods Forty male Wistar rats were divided into four equal groups; control group with free access to food and water, cholesterol administered group (40 mg/kg BW orally); karela administered group (5 g /kg BW orally) and mixture of cholesterol and karela. The treatments continued for 10 weeks. Karela was given for hypercholesterolemic rats after 6 weeks of cholesterol administration. Serum, liver and epididymal adipose tissues were taken for biochemical, histopathological and genetic assessments. Results Hypercholesterolemia induced a decrease in serum superoxide dismutase (SOD), catalase, reduced glutathione (GSH) and an increase in malondialdehyde (MDA) levels that were ameliorated by karela administration. Hypercholesterolemia up regulated antioxidants mRNA expression and altered the expression of carbohydrate metabolism genes. In parallel, hypercholesterolemic groups showed significant changes in the expression of PPAR-alpha and gamma, lipolysis, lipogenesis and cholesterol metabolism such as carnitine palmitoyltransferase-1 (CPT-1). Acyl CoA oxidase (ACO), fatty acids synthase (FAS), sterol responsible element binding protein-1c (SREBP1c), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR) and cholesterol 7α-hydroxylase (CYP7A1) at hepatic and adipose tissue levels. Interestingly, Karela ameliorated all altered genes confirming its hypocholesterolemic effect. Histopathological and immunohistochemical findings revealed that hypercholesterolemia induced hepatic tissue changes compared with control. These changes include cholesterol clefts, necrosis, karyolysis and sever congestion of portal blood vessel. Caspase-3 immunoreactivity showed positive expression in hepatic cells of hypercholesterolemic rats compared to control. All were counteracted and normalized after Karela administration to hypercholesterolemic group. Conclusion Current findings confirmed that karela is a potential supplement useful in treatment of hypercholesterolemia and its associated disorders and is good for human health.
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Abd Eldaim MA, Matsuoka S, Okamatsu-Ogura Y, Kamikawa A, Ahmed MM, Terao A, Nakajima KI, Kimura K. Retinoic acid modulates lipid accumulation glucose concentration dependently through inverse regulation of SREBP-1 expression in 3T3L1 adipocytes. Genes Cells 2017; 22:568-582. [PMID: 28488421 DOI: 10.1111/gtc.12498] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 03/29/2017] [Indexed: 12/19/2022]
Abstract
It is well known that retinoic acid (RA) suppresses adipogenesis, although there are some contradicting reports. In this study, we examined the effect of extracellular glucose on RA-induced suppression of adipogenesis in 3T3L1 cell culture. When the cells were cultured in normal glucose medium (NG), the addition of RA suppressed lipid accumulation. However, when cultured in high glucose medium (HG), addition of RA to the cells enhanced lipid accumulation. These changes were accompanied by parallel alterations in fatty acid synthase (FAS) and sterol regulatory element-binding protein (SREBP)-1 gene expression. Transfection of SREBP-1 siRNA suppressed RA-induced enhancement of lipid accumulation and FAS expression in the cells cultured with HG. Transfection of the nuclear form of SREBP-1a cDNA into the cells cultured with NG inhibited RA-induced suppression of lipid accumulation and FAS expression. Moreover, RA- and HG-induced SREBP-1a expression occurred at the early phase of adipogenesis and was dependent on glucocorticoid to induce liver X receptor (LXR) β, peroxisomal proliferator-activated receptor (PPAR) γ and retinoid X receptor (RXR), the key nuclear factors influencing the SREBP-1a gene expression. These results suggest that RA suppresses and enhances lipid accumulation through extracellular glucose concentration-dependent modulation of SREBP-1 expression.
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Affiliation(s)
- Mabrouk Attia Abd Eldaim
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan.,Department of Biochemistry and Chemistry of Nutrition, Faculty of Veterinary Medicine, Menoufia University, Menoufia, 32721, Egypt
| | - Shinya Matsuoka
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Yuko Okamatsu-Ogura
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Akihiro Kamikawa
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Mohamed Mohamed Ahmed
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Akira Terao
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Kei-Ichi Nakajima
- National Agricultural Research Center for Hokkaido Region, Sapporo, 062-8555, Japan
| | - Kazuhiro Kimura
- Laboratories of Biochemistry, Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
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11
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Takahashi Y, Shinoda A, Kamada H, Shimizu M, Inoue J, Sato R. Perilipin2 plays a positive role in adipocytes during lipolysis by escaping proteasomal degradation. Sci Rep 2016; 6:20975. [PMID: 26876687 PMCID: PMC4753471 DOI: 10.1038/srep20975] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 01/14/2016] [Indexed: 12/18/2022] Open
Abstract
Perilipin2 (Plin2), also known as adipose differentiation-related protein (ADRP), or adipophilin, is a member of the PAT family involved in lipid droplet (LD) formation in the liver and peripheral tissues. Although Plin2 was originally identified as a highly expressed gene in adipocytes, its physiological role in mature adipocytes is largely unknown. In this report, we investigated the regulation of Plin2 expression and its function in differentiated adipocytes of mouse embryonic fibroblasts (MEFs). Plin2 mRNA levels increased during adipocyte differentiation whereas protein levels did not. Plin2 was degraded through the ubiquitin-proteasome pathway but was inhibited by lipolytic inducers. Furthermore, lentiviral-mediated Plin2 knockdown attenuated lipolysis in differentiated MEFs in a time-dependent manner. Oleic acid-induced LD formation enhanced Plin2 protein stability when it was localized to LDs. Furthermore, a mutational analysis revealed that the ubiquitination and degradation of Plin2 required both the second and third alanine in the N-terminal region. These results suggest that Plin2 is degraded in the cytosol in its N-terminal amino acid sequence-dependent manner and instead becomes stable when localized on LDs. Our findings highlight the relationship between protein stability and a previously unnoticed function of Plin2 during lipolysis in adipocytes.
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Affiliation(s)
- Yu Takahashi
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Akihiro Shinoda
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Haruhiko Kamada
- Laboratory of Biopharmaceutical Research, National Institute of Biomedical Innovation, Osaka, Japan.,The Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka, Japan
| | - Makoto Shimizu
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Jun Inoue
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Ryuichiro Sato
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
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Takano Y, Sato R, Satsu H, Shimizu M. Characterization of the Human Intestinal Calcium Transporter, CaT1, Stably Expressed in CHO Cells. Cytotechnology 2011; 43:113-20. [PMID: 19003215 DOI: 10.1023/b:cyto.0000039904.17298.42] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The human calcium transporter, hCaT1, was cloned and analyzed. The obtained amino acid sequence was slightly different from the ortholog of hCaT1 which had been identified by Peng et al. (2000. Biochem. Biophys. Res. Commun 278: 326-332). An mRNA analysis of human gastrointestinal segments demonstrates that hCaT1 was expressed in the stomach, duodenum, jejunum, ileum, ileocecum, cecum, ascending colon, transverse colon, descending colon, and, at very low levels, in the esophagus and rectum. hCaT1 was transiently expressed by transfecting COS-1 cells and was stably expressed by the transfected CHO cells. The transfected cells expressed hCaT1 with a molecular mass of 75 kDa. Stable expression of hCaT1 in the CHO cells increased the cellular uptake of Ca(2+). hCaT1 was inhibited by La(3+), Gd(3+) and Cd(2+), whereas Co(2+), Fe(2+), Mn(2+) and Mg(2+) showed no significant effects on the activity. Acidification of the extracellular solution to pH 5.5 reduced the (45)Ca(2+)uptake by hCaT1 in the CHO cells. The addition of lactose and raffinose had no effect on the (45)Ca(2+) uptake, whereas galactose and glucose increased the (45)Ca(2+) uptake. CHO cells stably expressing hCaT1 will be useful to detect and analyze food substances that could modulate the hCaT1 activity.
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Affiliation(s)
- Yoshihiko Takano
- Department of Applied Biological Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo, 113-9657, Japan
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13
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Takahashi Y, Shinoda A, Inoue J, Sato R. The gene expression of the myocardial lipid droplet protein is highly regulated by PPARγ in adipocytes differentiated from MEFs or SVCs. Biochem Biophys Res Commun 2010; 399:209-14. [DOI: 10.1016/j.bbrc.2010.07.056] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 07/15/2010] [Indexed: 12/14/2022]
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Nerurkar PV, Lee YK, Nerurkar VR. Momordica charantia (bitter melon) inhibits primary human adipocyte differentiation by modulating adipogenic genes. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2010; 10:34. [PMID: 20587058 PMCID: PMC2911406 DOI: 10.1186/1472-6882-10-34] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 06/29/2010] [Indexed: 11/10/2022]
Abstract
BACKGROUND Escalating trends of obesity and associated type 2 diabetes (T2D) has prompted an increase in the use of alternative and complementary functional foods. Momordica charantia or bitter melon (BM) that is traditionally used to treat diabetes and complications has been demonstrated to alleviate hyperglycemia as well as reduce adiposity in rodents. However, its effects on human adipocytes remain unknown. The objective of our study was to investigate the effects of BM juice (BMJ) on lipid accumulation and adipocyte differentiation transcription factors in primary human differentiating preadipocytes and adipocytes. METHODS Commercially available cryopreserved primary human preadipocytes were treated with and without BMJ during and after differentiation. Cytotoxicity, lipid accumulation, and adipogenic genes mRNA expression was measured by commercial enzymatic assay kits and semi-quantitative RT-PCR (RT-PCR). RESULTS Preadipocytes treated with varying concentrations of BMJ during differentiation demonstrated significant reduction in lipid content with a concomitant reduction in mRNA expression of adipocyte transcription factors such as, peroxisome proliferator-associated receptor gamma (PPARgamma) and sterol regulatory element-binding protein 1c (SREBP-1c) and adipocytokine, resistin. Similarly, adipocytes treated with BMJ for 48 h demonstrated reduced lipid content, perilipin mRNA expression, and increased lipolysis as measured by the release of glycerol. CONCLUSION Our data suggests that BMJ is a potent inhibitor of lipogenesis and stimulator of lipolysis activity in human adipocytes. BMJ may therefore prove to be an effective complementary or alternative therapy to reduce adipogenesis in humans.
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Affiliation(s)
- Pratibha V Nerurkar
- Laboratory of Metabolic Disorders and Alternative Medicine, Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa, Honolulu, Hawaii 96822 USA
| | - Yun-Kung Lee
- Laboratory of Metabolic Disorders and Alternative Medicine, Department of Molecular Biosciences and Bioengineering, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa, Honolulu, Hawaii 96822 USA
| | - Vivek R Nerurkar
- Retrovirology Research Laboratory, Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii 96813 USA
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Suh JH, Gong EY, Kim JB, Lee IK, Choi HS, Lee K. Sterol regulatory element-binding protein-1c represses the transactivation of androgen receptor and androgen-dependent growth of prostatic cells. Mol Cancer Res 2008; 6:314-24. [PMID: 18245227 DOI: 10.1158/1541-7786.mcr-07-0354] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sterol regulatory element-binding protein-1c (SREBP-1c) is a basic helix-loop-helix transcription factor that plays an important role in lipid homeostasis. Here, we show that SREBP-1c regulates androgen receptor (AR) transactivation through direct interaction with AR and represses androgen-dependent growth of prostatic cells. Transient transfection studies show that SREBP-1c specifically inhibits the transactivation of AR. Chromatin immunoprecipitation assays reveal that SREBP-1c is recruited with AR onto the endogenous AR target promoter. Moreover, adenovirus-mediated overexpression of SREBP-1c decreases the mRNA level of the prostate-specific antigen gene, an endogenous target gene of AR, supporting SREBP-1c modulation of AR transactivation. In vivo and in vitro protein interaction assays show that SREBP-1c directly interacts with AR through the activation function-1 domain of AR. In addition, transfection studies and glutathione S-transferase pull-down competition experiments reveal that the SREBP-1c-mediated repression of AR transactivation is accomplished through competition with certain AR coactivators for AR interaction. The SREBP-1c-mediated inhibition of AR transactivation also involves the recruitment of histone deacetylase 1. Finally, adenovirus-mediated overexpression of SREBP-1c inhibits androgen-induced proliferation of prostatic cells in vitro and in vivo, and small interfering RNA-mediated down-regulation of SREBP-1 enhances androgen-induced proliferation of prostatic cells as well as the transactivation of AR. Taken together, these results suggest that SREBP-1c acts as an AR corepressor and may play an important role in the regulation of AR-dependent prostatic cell growth.
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Affiliation(s)
- Ji Ho Suh
- Hormone Research Center, Chonnam National University, Gwangju, Republic of Korea
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16
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Im SS, Kwon SK, Kang SY, Kim TH, Kim HI, Hur MW, Kim KS, Ahn YH. Regulation of GLUT4 gene expression by SREBP-1c in adipocytes. Biochem J 2006; 399:131-9. [PMID: 16787385 PMCID: PMC1570175 DOI: 10.1042/bj20060696] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Expression of the GLUT4 (glucose transporter type 4 isoform) gene in adipocytes is subject to hormonal or metabolic control. In the present study, we have characterized an adipose tissue transcription factor that is influenced by fasting/refeeding regimens and insulin. Northern blotting showed that refeeding increased GLUT4 mRNA levels for 24 h in adipose tissue. Consistent with an increased GLUT4 gene expression, the mRNA levels of SREBP (sterol-regulatory-element-binding protein)-1c in adipose tissue were also increased by refeeding. In streptozotocin-induced diabetic rats, insulin treatment increased the mRNA levels of GLUT4 in adipose tissue. Serial deletion, luciferase reporter assays and electrophoretic mobility-shift assay studies indicated that the putative sterol response element is located in the region between bases -109 and -100 of the human GLUT4 promoter. Transduction of the SREBP-1c dominant negative form to differentiated 3T3-L1 adipocytes caused a reduction in the mRNA levels of GLUT4, suggesting that SREBP-1c mediates the transcription of GLUT4. In vivo chromatin immunoprecipitation revealed that refeeding increased the binding of SREBP-1 to the putative sterol-response element in the GLUT4. Furthermore, treating streptozotocin-induced diabetic rats with insulin restored SREBP-1 binding. In addition, we have identified an Sp1 binding site adjacent to the functional sterol-response element in the GLUT4 promoter. The Sp1 site appears to play an additive role in SREBP-1c mediated GLUT4 gene upregulation. These results suggest that upregulation of GLUT4 gene transcription might be directly mediated by SREBP-1c in adipose tissue.
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Affiliation(s)
- Seung-Soon Im
- *Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- †Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- ‡Center for Chronic Metabolic Disease Research, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
| | - Sool-Ki Kwon
- *Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- †Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- ‡Center for Chronic Metabolic Disease Research, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
| | - Seung-Youn Kang
- ‡Center for Chronic Metabolic Disease Research, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
| | - Tae-Hyun Kim
- *Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- †Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- ‡Center for Chronic Metabolic Disease Research, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
| | - Ha-Il Kim
- *Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- ‡Center for Chronic Metabolic Disease Research, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
| | - Man-Wook Hur
- *Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- †Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
| | - Kyung-Sup Kim
- *Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- †Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- ‡Center for Chronic Metabolic Disease Research, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- §The Institute of Genetic Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
| | - Yong-Ho Ahn
- *Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- †Brain Korea 21 Project for Medical Sciences, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- ‡Center for Chronic Metabolic Disease Research, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemoon-gu, Seoul 120-752, Korea
- To whom correspondence should be addressed (email )
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Hackl H, Burkard TR, Sturn A, Rubio R, Schleiffer A, Tian S, Quackenbush J, Eisenhaber F, Trajanoski Z. Molecular processes during fat cell development revealed by gene expression profiling and functional annotation. Genome Biol 2005; 6:R108. [PMID: 16420668 PMCID: PMC1414107 DOI: 10.1186/gb-2005-6-13-r108] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Revised: 08/23/2005] [Accepted: 11/08/2005] [Indexed: 12/31/2022] Open
Abstract
In-depth bioinformatics analyses of expressed sequence tags found to be differentially expressed during differentiation of 3T3-L1 pre-adipocyte cells were combined with de novo functional annotation and mapping onto known pathways to generate a molecular atlas of fat-cell development. Background Large-scale transcription profiling of cell models and model organisms can identify novel molecular components involved in fat cell development. Detailed characterization of the sequences of identified gene products has not been done and global mechanisms have not been investigated. We evaluated the extent to which molecular processes can be revealed by expression profiling and functional annotation of genes that are differentially expressed during fat cell development. Results Mouse microarrays with more than 27,000 elements were developed, and transcriptional profiles of 3T3-L1 cells (pre-adipocyte cells) were monitored during differentiation. In total, 780 differentially expressed expressed sequence tags (ESTs) were subjected to in-depth bioinformatics analyses. The analysis of 3'-untranslated region sequences from 395 ESTs showed that 71% of the differentially expressed genes could be regulated by microRNAs. A molecular atlas of fat cell development was then constructed by de novo functional annotation on a sequence segment/domain-wise basis of 659 protein sequences, and subsequent mapping onto known pathways, possible cellular roles, and subcellular localizations. Key enzymes in 27 out of 36 investigated metabolic pathways were regulated at the transcriptional level, typically at the rate-limiting steps in these pathways. Also, coexpressed genes rarely shared consensus transcription-factor binding sites, and were typically not clustered in adjacent chromosomal regions, but were instead widely dispersed throughout the genome. Conclusions Large-scale transcription profiling in conjunction with sophisticated bioinformatics analyses can provide not only a list of novel players in a particular setting but also a global view on biological processes and molecular networks.
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Affiliation(s)
- Hubert Hackl
- Institute for Genomics and Bioinformatics and Christian Doppler Laboratory for Genomics and Bioinformatics, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
| | - Thomas Rainer Burkard
- Institute for Genomics and Bioinformatics and Christian Doppler Laboratory for Genomics and Bioinformatics, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
- Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria
| | - Alexander Sturn
- Institute for Genomics and Bioinformatics and Christian Doppler Laboratory for Genomics and Bioinformatics, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
| | - Renee Rubio
- Dana-Farber Cancer Institute, Department of Biostatistics and Computational Biology, 44 Binney Street, Boston, MA 02115
| | - Alexander Schleiffer
- Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria
| | - Sun Tian
- Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria
| | - John Quackenbush
- Dana-Farber Cancer Institute, Department of Biostatistics and Computational Biology, 44 Binney Street, Boston, MA 02115
| | - Frank Eisenhaber
- Research Institute of Molecular Pathology, Dr Bohr-Gasse 7, 1030 Vienna, Austria
| | - Zlatko Trajanoski
- Institute for Genomics and Bioinformatics and Christian Doppler Laboratory for Genomics and Bioinformatics, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
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Madsen L, Petersen RK, Kristiansen K. Regulation of adipocyte differentiation and function by polyunsaturated fatty acids. Biochim Biophys Acta Mol Basis Dis 2005; 1740:266-86. [PMID: 15949694 DOI: 10.1016/j.bbadis.2005.03.001] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Revised: 02/23/2005] [Accepted: 03/02/2005] [Indexed: 12/11/2022]
Abstract
A diet enriched in PUFAs, in particular of the n-3 family, decreases adipose tissue mass and suppresses development of obesity in rodents. Although several nuclear hormone receptors are identified as PUFA targets, the precise molecular mechanisms underlying the effects of PUFAs still remain to be elucidated. Here we review research aimed at elucidating molecular mechanisms governing the effects of PUFAs on the differentiation and function of white fat cells. This review focuses on dietary PUFAs as signaling molecules, with special emphasis on agonistic and antagonistic effects on transcription factors currently implicated as key players in adipocyte differentiation and function, including peroxisome proliferator activated receptors (PPARs) (alpha, beta and gamma), sterol regulatory element binding proteins (SREBPs) and liver X receptors (LXRs). We review evidence that dietary n-3 PUFAs decrease adipose tissue mass and suppress the development of obesity in rodents by targeting a set of key regulatory transcription factors involved in both adipogensis and lipid homeostasis in mature adipocytes. The same set of factors are targeted by PUFAs of the n-6 family, but the cellular/physiological responses are dependent on the experimental setting as n-6 PUFAs may exert either an anti- or a proadipogenic effect. Feeding status and hormonal background may therefore be of particular importance in determining the physiological effects of PUFAs of the n-6 family.
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Affiliation(s)
- Lise Madsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
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Smith LH, Petrie MS, Morrow JD, Oates JA, Vaughan DE. The sterol response element binding protein regulates cyclooxygenase-2 gene expression in endothelial cells. J Lipid Res 2005; 46:862-71. [PMID: 15716578 DOI: 10.1194/jlr.m500021-jlr200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously demonstrated that cholesterol deprivation increases endothelial cyclooxygenase-2 (COX-2)-dependent prostacyclin [prostaglandin I2 (PGI2)] production in vitro. Cholesterol directly regulates gene transcription through the sterol response element binding protein (SREBP). In this work, we demonstrate that SREBP directly regulates COX-2 expression. Cholesterol reduces human COX-2 promoter-luciferase reporter construct activity in transiently transfected endothelial cells. Conversely, cotransfection with a constitutively active mutant SREBP increases COX-2 promoter activity. SREBP-1a and -2 specifically bind a putative sterol response element (SRE) sequence in the COX-2 promoter. This sequence competes for SREBP binding to a low density lipoprotein receptor consensus sequence in an electromobility-shift assay. These data indicate that endothelial COX-2 is regulated by cholesterol via the SREBP pathway. The present study identifies COX-2 as the first vascular gene without a clear role in lipid metabolism transactivated by SREBP, and suggests that enhanced production of PGI2 through this pathway may be an additional benefit of cholesterol-lowering therapies.
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Affiliation(s)
- Layton Harris Smith
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
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Arimura N, Horiba T, Imagawa M, Shimizu M, Sato R. The Peroxisome Proliferator-activated Receptor γ Regulates Expression of the Perilipin Gene in Adipocytes. J Biol Chem 2004; 279:10070-6. [PMID: 14704148 DOI: 10.1074/jbc.m308522200] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent studies have shown that lipid droplets are covered with a proteinaceous coat, although the functions and identities of the component proteins have not yet been well elucidated. The first identified lipid droplet-specific proteins are the perilipins, a family of proteins coating the surfaces of lipid droplets of adipocytes. The generation of perilipin-null mice has revealed that although they consume more food than control mice, they have normal body weight and are resistant to diet-induced obesity. In one study (Martinez-Botas, J., Anderson, J. B., Tessier, D., Lapillonne, A., Chang, B. H. J., Quast, M. J., Gorenstein, D., Chen, K. H., and Chan, L. (2000) Nat. Genet. 26, 474-479) it was reported that in an animal model obesity was reversible by breeding perilipin -/- alleles into Lepr db/db obese mice, ostensibly by increasing the metabolic rate of the mice. To understand the exact mechanisms that drive the exclusive expression of the perilipin gene in adipocytes, we analyzed the 5'-flanking region of the mouse gene. Treatment of differentiating 3T3-L1 adipocytes with an agonist of proliferator-activated receptor (PPAR) gamma, the putative "master regulator" of adipocyte differentiation, significantly augmented perilipin gene expression. Reporter assays using the -2.0-kb promoter revealed that this region contains a functional PPARgamma-responsive element. Gel mobility shift and chromatin immunoprecipitation assays showed that endogenous PPARgamma protein binds to the perilipin promoter. PPARgamma2, an isoform exclusively expressed in adipocytes, was found to be the most potent regulator from among the PPAR family members including PPARalpha and PPARgamma1. These results make evident the fact that perilipin gene expression in differentiating adipocytes is crucially regulated by PPARgamma2, providing new insights into the adipogenic action of PPARgamma2 and adipose-specific gene expression, as well as potential anti-obesity pharmaceutical agents targeted to a reduction of the perilipin gene product.
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Affiliation(s)
- Naoto Arimura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
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21
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Lagace DC, Nachtigal MW. Inhibition of histone deacetylase activity by valproic acid blocks adipogenesis. J Biol Chem 2004; 279:18851-60. [PMID: 14985358 DOI: 10.1074/jbc.m312795200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Adipogenesis is dependent on the sequential activation of transcription factors including the CCAAT/enhancer-binding proteins (C/EBP), peroxisome proliferator-activated receptor gamma (PPARgamma), and steroid regulatory element-binding protein (SREBP). We show that the mood stabilizing drug valproic acid (VPA; 0.5-2 mm) inhibits mouse 3T3 L1 and human preadipocyte differentiation, likely through its histone deacetylase (HDAC) inhibitory properties. The HDAC inhibitor trichostatin A (TSA) also inhibited adipogenesis, whereas the VPA analog valpromide, which does not possess HDAC inhibitory effects, did not prevent adipogenesis. Acute or chronic VPA treatment inhibited differentiation yet did not affect mitotic clonal expansion. VPA (1 mm) inhibited PPARgamma induced differentiation but does not activate a PPARgamma reporter gene, suggesting that it is not a PPARgamma ligand. VPA or TSA treatment reduced mRNA and protein levels of PPARgamma and SREBP1a. TSA reduced C/EBPalpha mRNA and protein levels, whereas VPA only produced a decrease in C/EBPalpha protein expression. Overall our results highlight a role for HDAC activity in adipogenesis that can be blocked by treatment with VPA.
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Affiliation(s)
- Diane C Lagace
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
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22
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Lee YS, Lee HH, Park J, Yoo EJ, Glackin CA, Choi YI, Jeon SH, Seong RH, Park SD, Kim JB. Twist2, a novel ADD1/SREBP1c interacting protein, represses the transcriptional activity of ADD1/SREBP1c. Nucleic Acids Res 2004; 31:7165-74. [PMID: 14654692 PMCID: PMC291873 DOI: 10.1093/nar/gkg934] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Adipocyte determination and differentiation dependent factor 1 (ADD1)/sterol regulatory element binding protein isoform (SREBP1c) is a key transcription factor in fatty acid metabolism and insulin- dependent gene expression. Although its transcriptional and post-translational regulation has been extensively studied, its regulation by interacting proteins is not well understood. To identify cellular proteins that associate with ADD1/SREBP1c, we employed the yeast two-hybrid system with an adipocyte cDNA library. Using the N-terminal domain of ADD1/SREBP1c as bait, we identified Twist2 (also known as Dermo-1), a basic helix-loop-helix (bHLH) protein, as a novel ADD1/SREBP1c interacting protein. Over-expression of Twist2 strongly repressed the transcriptional activity of ADD1/SREBP1c, primarily by reducing its binding to target sequences. Inhibition of histone deacetylase (HDAC) activity with HDAC inhibitors relieved this repression. Our data suggest that physical interaction between Twist2 and ADD1/SREBP1c attenuates transcriptional activation by ADD1/SREBP1c by inhibiting its binding to DNA, and that this inhibition is at least partly dependent on chromatin modification by HDACs.
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Affiliation(s)
- Yun Sok Lee
- School of Biological Sciences, Seoul National University, Seoul 151-742, Korea
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Okada T, Haze K, Nadanaka S, Yoshida H, Seidah NG, Hirano Y, Sato R, Negishi M, Mori K. A serine protease inhibitor prevents endoplasmic reticulum stress-induced cleavage but not transport of the membrane-bound transcription factor ATF6. J Biol Chem 2003; 278:31024-32. [PMID: 12782636 DOI: 10.1074/jbc.m300923200] [Citation(s) in RCA: 168] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mammalian cells express several transcription factors embedded in the endoplasmic reticulum (ER) as transmembrane proteins that are activated by proteolysis, and two types of these proteins have been extensively investigated. One type comprises the sterol regulatory element-binding proteins (SREBP-1 and SREBP-2). The other type comprises the activating transcription factors 6 (ATF6alpha and ATF6beta), which are activated in response to ER stress. It was shown previously that both SREBP and ATF6 are cleaved sequentially first by the Site-1 protease (serine protease) and then by the Site-2 protease (metalloprotease) (Ye, J., Rawson, R. B., Komuro, R., Chen, X., Dave, U. P., Prywes, R., Brown, M. S., and Goldstein, J. L. (2000) Mol. Cell 6, 1355-1364). In this study, we examined various protease inhibitors and found that 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF), a serine protease inhibitor, prevented ER stress-induced cleavage of ATF6alpha and ATF6beta, resulting in inhibition of transcriptional induction of ATF6-target genes. AEBSF also inhibited production of the mature form of SREBP-2 that was induced in response to sterol depletion, and appeared to directly prevent cleavage of ATF6alpha and ATF6beta by inhibiting Site-1 protease. As the Site-1 protease is localized in the Golgi apparatus, both SREBP and ATF6 must relocate to the Golgi apparatus to be cleaved. We showed here that AEBSF treatment had little effect on ER stress-induced translocation of ATF6 from the ER to the Golgi apparatus, but blocked nuclear localization of ATF6. These results indicate that the transport of ATF6 from the ER to the Golgi apparatus and that from the Golgi apparatus to the nucleus are distinct steps that can be distinguished by treatment with AEBSF.
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Affiliation(s)
- Tetsuya Okada
- Graduate School of Biostudies, Kyoto University, Kyoto 606-8304, Japan
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24
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Hirano Y, Murata S, Tanaka K, Shimizu M, Sato R. Sterol regulatory element-binding proteins are negatively regulated through SUMO-1 modification independent of the ubiquitin/26 S proteasome pathway. J Biol Chem 2003; 278:16809-19. [PMID: 12615929 DOI: 10.1074/jbc.m212448200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Sterol regulatory element-binding proteins (SREBPs) are major transcription factors that activate the genes involved in cholesterol and fatty acid biosynthesis. We here report that the nuclear forms of SREBPs are modified by the small ubiquitin-related modifier (SUMO)-1. Mutational analyses identified two major sumoylation sites (Lys(123) and Lys(418)) in SREBP-1a and a single site (Lys(464)) in SREBP-2. Mutant SREBPs lacking one or two sumoylation sites exhibited increased transactivation capacity on an SREBP-responsive promoter. Overexpression of SUMO-1 reduced whereas its dominant negative form increased mRNA levels of SREBP-responsive genes. Nuclear SREBPs interacted with the SUMO-1-conjugating enzyme Ubc9, and overexpression of a dominant negative form of Ubc9 increased the mRNA levels of SREBP-responsive genes. Pulse-chase experiments revealed that sumoylation did not affect the degradation of SREBPs through the ubiquitin-proteasome pathway. In vitro ubiquitylation assay showed no competition between ubiquitin and SUMO-1 for the same lysine. Considered together, our results indicate that SUMO-1 modification suppresses the transactivation capacity of nuclear SREBPs in a manner different from the negative regulatory mechanism mediated by proteolysis.
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Affiliation(s)
- Yuko Hirano
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo 113-8657, Japan
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Wang H, Liu F, Millette CF, Kilpatrick DL. Expression of a novel, sterol-insensitive form of sterol regulatory element binding protein 2 (SREBP2) in male germ cells suggests important cell- and stage-specific functions for SREBP targets during spermatogenesis. Mol Cell Biol 2002; 22:8478-90. [PMID: 12446768 PMCID: PMC139869 DOI: 10.1128/mcb.22.24.8478-8490.2002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Cholesterol biosynthesis in somatic cells is controlled at the transcriptional level by a homeostatic feedback pathway involving sterol regulatory element binding proteins (SREBPs). These basic helix-loop-helix (bHLH)-Zip proteins are synthesized as membrane-bound precursors, which are cleaved to form a soluble, transcriptionally active mature SREBP that regulates the promoters for genes involved in lipid synthesis. Homeostasis is conferred by sterol feedback inhibition of this maturation process. Previous work has demonstrated the expression of SREBP target genes in the male germ line, several of which are highly up-regulated during specific developmental stages. However, the role of SREBPs in the control of sterol regulatory element-containing promoters during spermatogenesis has been unclear. In particular, expression of several of these genes in male germ cells appears to be insensitive to sterols, contrary to SREBP-dependent gene regulation in somatic cells. Here, we have characterized a novel isoform of the transcription factor SREBP2, which is highly enriched in rat and mouse spermatogenic cells. This protein, SREBP2gc, is expressed in a stage-dependent fashion as a soluble, constitutively active transcription factor that is not subject to feedback control by sterols. These findings likely explain the apparent sterol-insensitive expression of lipid synthesis genes during spermatogenesis. Expression of a sterol-independent, constitutively active SREBP2gc in the male germ line may have arisen as a means to regulate SREBP target genes in specific developmental stages. This may reflect unique roles for cholesterol synthesis and other functional targets of SREBPs during spermatogenesis.
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Affiliation(s)
- Hang Wang
- Department of Physiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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Nakahara M, Fujii H, Maloney PR, Shimizu M, Sato R. Bile acids enhance low density lipoprotein receptor gene expression via a MAPK cascade-mediated stabilization of mRNA. J Biol Chem 2002; 277:37229-34. [PMID: 12149270 DOI: 10.1074/jbc.m206749200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent studies have indicated that bile acids regulate the expression of several genes involved in bile acid and lipid metabolism as ligands for the farnesoid X receptor (FXR). We report here that bile acids are directly able to govern cholesterol metabolism by a novel mechanism. We show that chenodeoxycholic acid (CDCA) enhances low density lipoprotein (LDL) receptor gene expression in human cultured cell lines (HeLa, Hep G2, and Caco-2). The proteolytic activation of sterol regulatory element-binding protein-2 (SREBP-2), a major regulator for LDL receptor gene expression, is not affected by CDCA. Both deoxycholic acid and lithocholic acid as well as CDCA, but not ursodeoxycholic acid, increase the mRNA level for the LDL receptor, even when Hep G2 cells are cultured with 25-hydroxycholesterol, a potent suppressor of gene expression for the LDL receptor. Although it seems possible that FXR might be involved in genetic regulation, both reporter assays with a reporter gene containing the LDL receptor promoter as well as Northern blot analysis reveal that FXR is not involved in the process. On the other hand, inhibition of mitogen-activated protein (MAP) kinase activities, which are found to be induced by CDCA, abolishes the CDCA-mediated up-regulation of LDL receptor gene expression. We further demonstrate that CDCA stabilizes LDL receptor mRNA and that the MAP kinase inhibitors accelerate its turnover. Taken together, these results indicate that bile acids increase LDL uptake and the intracellular cholesterol levels through the activation of MAP kinase cascades in conjunction with a down-regulation of bile acid biosynthesis by FXR. This work opens up a new avenue for developing pharmaceutical interventions that lower plasma LDL by stabilizing LDL receptor mRNA.
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Affiliation(s)
- Mayuko Nakahara
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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