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Białek W, Hryniewicz-Jankowska A, Czechowicz P, Sławski J, Collawn JF, Czogalla A, Bartoszewski R. The lipid side of unfolded protein response. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159515. [PMID: 38844203 DOI: 10.1016/j.bbalip.2024.159515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/16/2024] [Accepted: 05/31/2024] [Indexed: 06/12/2024]
Abstract
Although our current knowledge of the molecular crosstalk between the ER stress, the unfolded protein response (UPR), and lipid homeostasis remains limited, there is increasing evidence that dysregulation of either protein or lipid homeostasis profoundly affects the other. Most research regarding UPR signaling in human diseases has focused on the causes and consequences of disrupted protein folding. The UPR itself consists of very complex pathways that function to not only maintain protein homeostasis, but just as importantly, modulate lipid biogenesis to allow the ER to adjust and promote cell survival. Lipid dysregulation is known to activate many aspects of the UPR, but the complexity of this crosstalk remains a major research barrier. ER lipid disequilibrium and lipotoxicity are known to be important contributors to numerous human pathologies, including insulin resistance, liver disease, cardiovascular diseases, neurodegenerative diseases, and cancer. Despite their medical significance and continuous research, however, the molecular mechanisms that modulate lipid synthesis during ER stress conditions, and their impact on cell fate decisions, remain poorly understood. Here we summarize the current view on crosstalk and connections between altered lipid metabolism, ER stress, and the UPR.
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Affiliation(s)
- Wojciech Białek
- Department of Biophysics, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | | | - Paulina Czechowicz
- Department of Biophysics, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Jakub Sławski
- Department of Biophysics, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - James F Collawn
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, USA
| | - Aleksander Czogalla
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Rafał Bartoszewski
- Department of Biophysics, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland.
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2
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Zhou S, Cheng K, Peng Y, Liu Y, Hu Q, Zeng S, Qi X, Yu L. Regulation mechanism of endoplasmic reticulum stress on metabolic enzymes in liver diseases. Pharmacol Res 2024; 207:107332. [PMID: 39089398 DOI: 10.1016/j.phrs.2024.107332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 07/28/2024] [Accepted: 07/29/2024] [Indexed: 08/04/2024]
Abstract
The endoplasmic reticulum (ER) plays a pivotal role in protein folding and secretion, Ca2+ storage, and lipid synthesis in eukaryotic cells. When the burden of protein synthesis and folding required to be handled exceeds the processing capacity of the ER, the accumulation of misfolded/unfolded proteins triggers ER stress. In response to short-term ER stress, the unfolded protein response (UPR) is activated to allow cells to survive. When ER stress is severe and sustained, it typically provokes cell death through multiple approaches. It is well documented that ER stress and metabolic deregulation are functionally intertwined, both are considered contributing factors to the pathogenesis of liver diseases, including non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), ischemia/reperfusion (I/R) injury, viral hepatitis, liver fibrosis, and hepatocellular carcinoma (HCC). Hepatocytes are rich in smooth and rough ER, which harbor metabolic enzymes that are capable of sensing alterations in various nutritional status and external stimuli. Extensive research has focused on the molecular mechanism linking ER stress with metabolic enzymes. The purpose of this review is to summarize the current knowledge regarding the effects of ER stress on metabolic enzymes in various liver diseases and to provide potential therapeutic strategies for chronic liver diseases via targeting UPR.
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Affiliation(s)
- Shaojun Zhou
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; National Key Laboratory of Advanced Drug Delivery and Release Systems, Zhejiang University, Hangzhou 310058, China
| | - Kaiwen Cheng
- Medical Research Center, Shaoxing People's Hospital (Shaoxing Hospital, Zhejiang University School of Medicine), Shaoxing 312000, China
| | - Yi Peng
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China
| | - Yuxi Liu
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; National Key Laboratory of Advanced Drug Delivery and Release Systems, Zhejiang University, Hangzhou 310058, China
| | - Qingqing Hu
- The Fourth Affiliated Hospital, School of Medicine, Zhejiang University, Jinhua 322023, China
| | - Su Zeng
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; National Key Laboratory of Advanced Drug Delivery and Release Systems, Zhejiang University, Hangzhou 310058, China
| | - Xuchen Qi
- Department of Pharmacy, Shaoxing People's Hospital (Shaoxing Hospital, Zhejiang University School of Medicine), Shaoxing 312000, China; Department of Neurosurgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310020, China.
| | - Lushan Yu
- Institute of Drug Metabolism and Pharmaceutical Analysis, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China; National Key Laboratory of Advanced Drug Delivery and Release Systems, Zhejiang University, Hangzhou 310058, China; Department of Pharmacy, Shaoxing People's Hospital (Shaoxing Hospital, Zhejiang University School of Medicine), Shaoxing 312000, China; Westlake Laboratory of Life Sciences and Biomedicine of Zhejiang Province, Hangzhou 310024, China; Department of Pharmacy, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China.
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3
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Zhang J, Zhang T, Chen Y, Xuan X, Zhao Y, Lu G. Spermidine mitigates ferroptosis in free fatty acid-induced AML-12 cells through the ATF4/SLC7A11/GCLM/GPX4 pathway. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159560. [PMID: 39181440 DOI: 10.1016/j.bbalip.2024.159560] [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: 01/16/2024] [Revised: 08/20/2024] [Accepted: 08/21/2024] [Indexed: 08/27/2024]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a prominent cause of chronic liver disease worldwide. Spermidine (SPD), a naturally occurring polyamine, has shown potential in alleviating the accumulation of hepatic lipids and reducing NAFLD symptoms in overweight mice. Nonetheless, the specific mechanisms through which SPD exerts its effects remain largely unknown. This study seeks to explore the protective effects of SPD on NAFLD and to clarify the underlying mechanisms. An in vitro model of NAFLD was established by inducing steatosis in AML-12 cells through the use of free fatty acids (FFAs). Our experimental results demonstrate that SPD significantly reduces NAFLD development induced by FFAs. This reduction is primarily achieved through the inhibition of cellular ferroptosis, as evidenced by decreased levels of Fe2+, malondialdehyde (MDA), and reactive oxygen species (ROS). Additionally, SPD was found to enhance cellular activity and ameliorate mitochondrial dysfunction and oxidative stress caused by FFA exposure. Further mechanistic studies have revealed that SPD upregulates the expression of solute transporter family 7a member 11 (SLC7A11), glutamate-cysteine ligase modifier subunit (GCLM), and glutathione peroxidase (GPX4). This upregulation is mediated by the activation of activating transcription factor 4 (ATF4). Knockdown experiments of ATF4 confirmed that its inhibition reverses the upregulation of SLC7A11, GCLM, and GPX4, thereby negating the protective effects of SPD. In conclusion, our findings suggest that SPD mitigates NAFLD by modulating the ATF4/SLC7A11/GCLM/GPX4 signaling pathway, resulting in the suppression of ferroptosis and the improvement of cellular health. These insights provide a novel molecular mechanism and identify potential therapeutic targets for the treatment of NAFLD.
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Affiliation(s)
- Jia Zhang
- Department of Gastroenterology, The Second Affiliated Hospital, Zhengzhou University, Zhengzhou 450000, China; Tianjian Laboratory of Advanced Biomedical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou 450000, China
| | - Tao Zhang
- Department of Gastroenterology, The Second Affiliated Hospital, Zhengzhou University, Zhengzhou 450000, China; Tianjian Laboratory of Advanced Biomedical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou 450000, China
| | - Yihang Chen
- Department of Gastroenterology, The Second Affiliated Hospital, Zhengzhou University, Zhengzhou 450000, China; Tianjian Laboratory of Advanced Biomedical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou 450000, China
| | - Xiaojie Xuan
- Department of Gastroenterology, The Second Affiliated Hospital, Zhengzhou University, Zhengzhou 450000, China; Tianjian Laboratory of Advanced Biomedical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou 450000, China
| | - Yuqian Zhao
- Department of Gastroenterology, The Second Affiliated Hospital, Zhengzhou University, Zhengzhou 450000, China; Tianjian Laboratory of Advanced Biomedical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou 450000, China
| | - Gaofeng Lu
- Department of Gastroenterology, The Second Affiliated Hospital, Zhengzhou University, Zhengzhou 450000, China; Tianjian Laboratory of Advanced Biomedical Sciences, Academy of Medical Sciences, Zhengzhou University, Zhengzhou 450000, China.
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Zhang X, Li Z, Zhang X, Yuan Z, Zhang L, Miao P. ATF family members as therapeutic targets in cancer: From mechanisms to pharmacological interventions. Pharmacol Res 2024; 208:107355. [PMID: 39179052 DOI: 10.1016/j.phrs.2024.107355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Revised: 08/09/2024] [Accepted: 08/15/2024] [Indexed: 08/26/2024]
Abstract
The activating transcription factor (ATF)/ cAMP-response element binding protein (CREB) family represents a large group of basic zone leucine zip (bZIP) transcription factors (TFs) with a variety of physiological functions, such as endoplasmic reticulum (ER) stress, amino acid stress, heat stress, oxidative stress, integrated stress response (ISR) and thus inducing cell survival or apoptosis. Interestingly, ATF family has been increasingly implicated in autophagy and ferroptosis in recent years. Thus, the ATF family is important for homeostasis and its dysregulation may promote disease progression including cancer. Current therapeutic approaches to modulate the ATF family include direct modulators, upstream modulators, post-translational modifications (PTMs) modulators. This review summarizes the structural domain and the PTMs feature of the ATF/CREB family and comprehensively explores the molecular regulatory mechanisms. On this basis, their pathways affecting proliferation, metastasis, and drug resistance in various types of cancer cells are sorted out and discussed. We then systematically summarize the status of the therapeutic applications of existing ATF family modulators and finally look forward to the future prospect of clinical applications in the treatment of tumors by modulating the ATF family.
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Affiliation(s)
- Xueyao Zhang
- Department of Anus and Intestine Surgery, Department of Cardiology, and Department of Respiratory and Critical Care Medicine, The First Hospital of China Medical University, Shenyang 110001, China
| | - Zhijia Li
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Xiaochun Zhang
- Department of Anus and Intestine Surgery, Department of Cardiology, and Department of Respiratory and Critical Care Medicine, The First Hospital of China Medical University, Shenyang 110001, China
| | - Ziyue Yuan
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Lan Zhang
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China.
| | - Peng Miao
- Department of Anus and Intestine Surgery, Department of Cardiology, and Department of Respiratory and Critical Care Medicine, The First Hospital of China Medical University, Shenyang 110001, China.
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5
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Zhang N, Nao J, Zhang S, Dong X. Novel insights into the activating transcription factor 4 in Alzheimer's disease and associated aging-related diseases: Mechanisms and therapeutic implications. Front Neuroendocrinol 2024; 74:101144. [PMID: 38797197 DOI: 10.1016/j.yfrne.2024.101144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 05/16/2024] [Accepted: 05/22/2024] [Indexed: 05/29/2024]
Abstract
Ageing is inherent to all human beings, most mechanistic explanations of ageing results from the combined effects of various physiological and pathological processes. Additionally, aging pivotally contributes to several chronic diseases. Activating transcription factor 4 (ATF4), a member of the ATF/cAMP response element-binding protein family, has recently emerged as a pivotal player owing to its indispensable role in the pathophysiological processes of Alzheimer's disease and aging-related diseases. Moreover, ATF4 is integral to numerous biological processes. Therefore, this article aims to comprehensively review relevant research on the role of ATF4 in the onset and progression of aging-related diseases, elucidating its potential mechanisms and therapeutic approaches. Our objective is to furnish scientific evidence for the early identification of risk factors in aging-related diseases and pave the way for new research directions for their treatment. By elucidating the signaling pathway network of ATF4 in aging-related diseases, we aspire to gain a profound understanding of the molecular and cellular mechanisms, offering novel strategies for addressing aging and developing related therapeutics.
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Affiliation(s)
- Nan Zhang
- Department of Neurology, the Seventh Clinical College of China Medical University, No. 24 Central Street, Xinfu District, Fushun 113000, Liaoning, China.
| | - Jianfei Nao
- Department of Neurology, Shengjing Hospital of China Medical University, No. 36 Sanhao Street, Heping District, Shenyang 110000, Liaoning, China.
| | - Shun Zhang
- Department of Neurology, Shengjing Hospital of China Medical University, No. 36 Sanhao Street, Heping District, Shenyang 110000, Liaoning, China.
| | - Xiaoyu Dong
- Department of Neurology, Shengjing Hospital of China Medical University, No. 36 Sanhao Street, Heping District, Shenyang 110000, Liaoning, China.
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Hazari Y, Chevet E, Bailly-Maitre B, Hetz C. ER stress signaling at the interphase between MASH and HCC. Hepatology 2024:01515467-990000000-00844. [PMID: 38626349 DOI: 10.1097/hep.0000000000000893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Accepted: 03/28/2024] [Indexed: 04/18/2024]
Abstract
HCC is the most frequent primary liver cancer with an extremely poor prognosis and often develops on preset of chronic liver diseases. Major risk factors for HCC include metabolic dysfunction-associated steatohepatitis, a complex multifactorial condition associated with abnormal endoplasmic reticulum (ER) proteostasis. To cope with ER stress, the unfolded protein response engages adaptive reactions to restore the secretory capacity of the cell. Recent advances revealed that ER stress signaling plays a critical role in HCC progression. Here, we propose that chronic ER stress is a common transversal factor contributing to the transition from liver disease (risk factor) to HCC. Interventional strategies to target the unfolded protein response in HCC, such as cancer therapy, are also discussed.
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Affiliation(s)
- Younis Hazari
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
- Faculty of Medicine, Biomedical Neuroscience Institute (BNI), University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Department of Biotechnology, University of Kashmir, Srinagar, India
| | - Eric Chevet
- Inserm U1242, University of Rennes, Rennes, France
- Centre de Lutte Contre le Cancer Eugène Marquis, Rennes, France
| | - Béatrice Bailly-Maitre
- Institut National de la Santé et de la Recherche Médicale (INSERM) UMR1065, Université Côte d'Azur (UCA), Centre Méditerranéen de Médecine Moléculaire (C3M), 06204 Nice, France Team "Metainflammation and Hematometabolism", Metabolism Department, France
- Université Côte d'Azur, INSERM, U1065, C3M, 06200 Nice, France
| | - Claudio Hetz
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
- Faculty of Medicine, Biomedical Neuroscience Institute (BNI), University of Chile, Santiago, Chile
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile
- Buck Institute for Research on Aging, Novato, California, USA
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7
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Grmai L, Michaca M, Lackner E, Nampoothiri V P N, Vasudevan D. Integrated stress response signaling acts as a metabolic sensor in fat tissues to regulate oocyte maturation and ovulation. Cell Rep 2024; 43:113863. [PMID: 38457339 DOI: 10.1016/j.celrep.2024.113863] [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: 03/21/2023] [Revised: 11/23/2023] [Accepted: 02/08/2024] [Indexed: 03/10/2024] Open
Abstract
Reproduction is an energy-intensive process requiring systemic coordination. However, the inter-organ signaling mechanisms that relay nutrient status to modulate reproductive output are poorly understood. Here, we use Drosophila melanogaster as a model to establish the integrated stress response (ISR) transcription factor, Atf4, as a fat tissue metabolic sensor that instructs oogenesis. We demonstrate that Atf4 regulates lipase activity to mediate yolk lipoprotein synthesis in the fat body. Depletion of Atf4 in the fat body also blunts oogenesis recovery after amino acid deprivation and re-feeding, suggestive of a nutrient-sensing role for Atf4. We also discovered that Atf4 promotes secretion of a fat-body-derived neuropeptide, CNMamide, which modulates neural circuits that promote egg-laying behavior (ovulation). Thus, we posit that ISR signaling in fat tissue acts as a "metabolic sensor" that instructs female reproduction-directly by impacting yolk lipoprotein production and follicle maturation and systemically by regulating ovulation.
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Affiliation(s)
- Lydia Grmai
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA
| | - Manuel Michaca
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Emily Lackner
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | | | - Deepika Vasudevan
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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Flores-Leon M, Outeiro TF. More than meets the eye in Parkinson's disease and other synucleinopathies: from proteinopathy to lipidopathy. Acta Neuropathol 2023; 146:369-385. [PMID: 37421475 PMCID: PMC10412683 DOI: 10.1007/s00401-023-02601-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 06/12/2023] [Accepted: 06/14/2023] [Indexed: 07/10/2023]
Abstract
The accumulation of proteinaceous inclusions in the brain is a common feature among neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease (PD), and dementia with Lewy bodies (DLB). The main neuropathological hallmark of PD and DLB are inclusions, known as Lewy bodies (LBs), enriched not only in α-synuclein (aSyn), but also in lipid species, organelles, membranes, and even nucleic acids. Furthermore, several genetic risk factors for PD are mutations in genes involved in lipid metabolism, such as GBA1, VSP35, or PINK1. Thus, it is not surprising that mechanisms that have been implicated in PD, such as inflammation, altered intracellular and vesicular trafficking, mitochondrial dysfunction, and alterations in the protein degradation systems, may be also directly or indirectly connected through lipid homeostasis. In this review, we highlight and discuss the recent evidence that suggests lipid biology as important drivers of PD, and which require renovated attention by neuropathologists. Particularly, we address the implication of lipids in aSyn accumulation and in the spreading of aSyn pathology, in mitochondrial dysfunction, and in ER stress. Together, this suggests we should broaden the view of PD not only as a proteinopathy but also as a lipidopathy.
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Affiliation(s)
- Manuel Flores-Leon
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37073, Göttingen, Germany
- Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, Ciudad de México, Mexico
| | - Tiago Fleming Outeiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, 37073, Göttingen, Germany.
- Max Planck Institute for Multidisciplinary Science, Göttingen, Germany.
- Faculty of Medical Sciences, Translational and Clinical Research Institute, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK.
- Scientific Employee with an Honorary Contract at Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Göttingen, Germany.
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He F, Zhang P, Liu J, Wang R, Kaufman RJ, Yaden BC, Karin M. ATF4 suppresses hepatocarcinogenesis by inducing SLC7A11 (xCT) to block stress-related ferroptosis. J Hepatol 2023; 79:362-377. [PMID: 36996941 PMCID: PMC11332364 DOI: 10.1016/j.jhep.2023.03.016] [Citation(s) in RCA: 74] [Impact Index Per Article: 74.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 03/02/2023] [Accepted: 03/06/2023] [Indexed: 04/01/2023]
Abstract
BACKGROUND & AIMS Hepatocellular carcinoma (HCC), a leading cause of cancer-related death, is associated with viral hepatitis, non-alcoholic steatohepatitis (NASH), and alcohol-related steatohepatitis, all of which trigger endoplasmic reticulum (ER) stress, hepatocyte death, inflammation, and compensatory proliferation. Using ER stress-prone MUP-uPA mice, we established that ER stress and hypernutrition cooperate to cause NASH and HCC, but the contribution of individual stress effectors, such as activating transcription factor 4 (ATF4), to HCC and their underlying mechanisms of action remained unknown. METHODS Hepatocyte-specific ATF4-deficient MUP-uPA mice (MUP-uPA/Atf4Δhep) and control MUP-uPA/Atf4F/F mice were fed a high-fat diet to induce NASH-related HCC, and Atf4F/F and Atf4Δhep mice were injected with diethylnitrosamine to model carcinogen-induced HCC. Histological, biochemical, and RNA-sequencing analyses were performed to identify and define the role of ATF4-induced solute carrier family 7a member 11 (SLC7A11) expression in hepatocarcinogenesis. Reconstitution of SLC7A11 in ATF4-deficient primary hepatocytes and mouse livers was used to study its effects on ferroptosis and HCC development. RESULTS Hepatocyte ATF4 ablation inhibited hepatic steatosis, but increased susceptibility to ferroptosis, resulting in accelerated HCC development. Although ATF4 activates numerous genes, ferroptosis susceptibility and hepatocarcinogenesis were reversed by ectopic expression of a single ATF4 target, Slc7a11, coding for a subunit of the cystine/glutamate antiporter xCT, which is needed for glutathione synthesis. A ferroptosis inhibitor also reduced liver damage and inflammation. ATF4 and SLC7A11 amounts were positively correlated in human HCC and livers of patients with NASH. CONCLUSIONS Despite ATF4 being upregulated in established HCC, it serves an important protective function in normal hepatocytes. By maintaining glutathione production, ATF4 inhibits ferroptosis-dependent inflammatory cell death, which is known to promote compensatory proliferation and hepatocarcinogenesis. Ferroptosis inhibitors or ATF4 activators may also blunt HCC onset. IMPACT AND IMPLICATIONS Liver cancer or hepatocellular carcinoma (HCC) is associated with multiple aetiologies. Most HCC aetiologies cause hepatocyte stress and death, as well as subsequent inflammation, and compensatory proliferation, thereby accelerating HCCdevelopment. The contribution of individual stress effectors to HCC and their underlying mechanisms of action were heretofore unknown. This study shows that the stress-responsive transcription factor ATF4 blunts liver damage and cancer development by suppressing iron-dependent cell death (ferroptosis). Although ATF4 ablation prevents hepatic steatosis, it also increases susceptibility to ferroptosis, due to decreased expression of the cystine/glutamate antiporter SLC7A11, whose expression in human HCC and NASH correlates with ATF4. These findings reinforce the notion that benign steatosis may be protective and does not increase cancer risk unless accompanied by stress-induced liver damage. These results have important implications for prevention of liver damage and cancer.
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Affiliation(s)
- Feng He
- Academy of Integrative Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China; Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, School of Medicine, University of California San Diego, San Diego, CA, USA.
| | - Peng Zhang
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, School of Medicine, University of California San Diego, San Diego, CA, USA
| | - Junlai Liu
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, School of Medicine, University of California San Diego, San Diego, CA, USA
| | - Ruolei Wang
- Academy of Integrative Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Randal J Kaufman
- Degenerative Diseases Program, Center for Genetic Disorders and Aging Research, SBP Medical Discovery Institute, La Jolla, CA, USA
| | - Benjamin C Yaden
- Diabetes Novel Therapies and External Innovation, Eli Lilly and Company, Indianapolis, IN, USA.
| | - Michael Karin
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, School of Medicine, University of California San Diego, San Diego, CA, USA; Department of Pathology, School of Medicine, University of California San Diego, San Diego, CA, USA.
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10
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Basha A, May SC, Anderson RM, Samala N, Mirmira RG. Non-Alcoholic Fatty Liver Disease: Translating Disease Mechanisms into Therapeutics Using Animal Models. Int J Mol Sci 2023; 24:9996. [PMID: 37373143 PMCID: PMC10298283 DOI: 10.3390/ijms24129996] [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: 05/17/2023] [Revised: 06/06/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a range of pathologies arising from fat accumulation in the liver in the absence of excess alcohol use or other causes of liver disease. Its complications include cirrhosis and liver failure, hepatocellular carcinoma, and eventual death. NAFLD is the most common cause of liver disease globally and is estimated to affect nearly one-third of individuals in the United States. Despite knowledge that the incidence and prevalence of NAFLD are increasing, the pathophysiology of the disease and its progression to cirrhosis remain insufficiently understood. The molecular pathogenesis of NAFLD involves insulin resistance, inflammation, oxidative stress, and endoplasmic reticulum stress. Better insight into these molecular pathways would allow for therapies that target specific stages of NAFLD. Preclinical animal models have aided in defining these mechanisms and have served as platforms for screening and testing of potential therapeutic approaches. In this review, we will discuss the cellular and molecular mechanisms thought to contribute to NAFLD, with a focus on the role of animal models in elucidating these mechanisms and in developing therapies.
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Affiliation(s)
- Amina Basha
- Kovler Diabetes Center, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL 60637, USA
| | - Sarah C. May
- Kovler Diabetes Center, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL 60637, USA
| | - Ryan M. Anderson
- Kovler Diabetes Center, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL 60637, USA
| | - Niharika Samala
- Department of Medicine, Division of Gastroenterology and Hepatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Raghavendra G. Mirmira
- Kovler Diabetes Center, Section of Adult and Pediatric Endocrinology, Diabetes and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL 60637, USA
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11
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Celik C, Lee SYT, Yap WS, Thibault G. Endoplasmic reticulum stress and lipids in health and diseases. Prog Lipid Res 2023; 89:101198. [PMID: 36379317 DOI: 10.1016/j.plipres.2022.101198] [Citation(s) in RCA: 37] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/03/2022] [Accepted: 11/09/2022] [Indexed: 11/14/2022]
Abstract
The endoplasmic reticulum (ER) is a complex and dynamic organelle that regulates many cellular pathways, including protein synthesis, protein quality control, and lipid synthesis. When one or multiple ER roles are dysregulated and saturated, the ER enters a stress state, which, in turn, activates the highly conserved unfolded protein response (UPR). By sensing the accumulation of unfolded proteins or lipid bilayer stress (LBS) at the ER, the UPR triggers pathways to restore ER homeostasis and eventually induces apoptosis if the stress remains unresolved. In recent years, it has emerged that the UPR works intimately with other cellular pathways to maintain lipid homeostasis at the ER, and so does at cellular levels. Lipid distribution, along with lipid anabolism and catabolism, are tightly regulated, in part, by the ER. Dysfunctional and overwhelmed lipid-related pathways, independently or in combination with ER stress, can have reciprocal effects on other cellular functions, contributing to the development of diseases. In this review, we summarize the current understanding of the UPR in response to proteotoxic stress and LBS and the breadth of the functions mitigated by the UPR in different tissues and in the context of diseases.
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Affiliation(s)
- Cenk Celik
- School of Biological Sciences, Nanyang Technological University, Singapore
| | | | - Wei Sheng Yap
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Guillaume Thibault
- School of Biological Sciences, Nanyang Technological University, Singapore; Mechanobiology Institute, National University of Singapore, Singapore; Institute of Molecular and Cell Biology, A*STAR, Singapore.
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12
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Florance I, Ramasubbu S. Current Understanding on the Role of Lipids in Macrophages and Associated Diseases. Int J Mol Sci 2022; 24:ijms24010589. [PMID: 36614031 PMCID: PMC9820199 DOI: 10.3390/ijms24010589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 11/30/2022] [Accepted: 12/09/2022] [Indexed: 12/31/2022] Open
Abstract
Lipid metabolism is the major intracellular mechanism driving a variety of cellular functions such as energy storage, hormone regulation and cell division. Lipids, being a primary component of the cell membrane, play a pivotal role in the survival of macrophages. Lipids are crucial for a variety of macrophage functions including phagocytosis, energy balance and ageing. However, functions of lipids in macrophages vary based on the site the macrophages are residing at. Lipid-loaded macrophages have recently been emerging as a hallmark for several diseases. This review discusses the significance of lipids in adipose tissue macrophages, tumor-associated macrophages, microglia and peritoneal macrophages. Accumulation of macrophages with impaired lipid metabolism is often characteristically observed in several metabolic disorders. Stress signals differentially regulate lipid metabolism. While conditions such as hypoxia result in accumulation of lipids in macrophages, stress signals such as nutrient deprivation initiate lipolysis and clearance of lipids. Understanding the biology of lipid accumulation in macrophages requires the development of potentially active modulators of lipid metabolism.
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13
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Yu D, Li J, Wang Y, Guo D, Zhang X, Chen M, Zhou Z. Oridonin ameliorates acetaminophen-induced acute liver injury through ATF4/PGC-1α pathway. Drug Dev Res 2022; 84:211-225. [PMID: 36567664 DOI: 10.1002/ddr.22024] [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: 07/18/2022] [Revised: 11/26/2022] [Accepted: 12/04/2022] [Indexed: 12/27/2022]
Abstract
Acetaminophen (APAP) overdose-induced acute liver injury (ALI) causes hepatocyte cell death, oxidative stress, and inflammation. Oridonin (Ori), a covalent NLRP3-inflammasome inhibitor, ameliorates APAP-induced ALI through an unclear molecular mechanism. This study found that Ori decreased hepatic cytochrome P450 2E1 level and increased glutathione content to prevent APAP metabolism, and then reduced the necrotic area, improved liver function, and inhibited APAP-induced proinflammatory cytokines and oxidative stress. Ori also decreased activating transcription factor 4 (ATF4) protein levels and increased peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) to reduce APAP-induced endoplasmic reticulum stress activation and mitochondrial dysfunction. Furthermore, western blot and luciferase assay found that ATF4 inhibited transcription in the PGC-1α promoter -507 to -495 region to reduce PGC-1α levels, while ATF4 knockdown neutralized the hepatoprotective effect of Ori. Molecular docking showed that Ori bound to ATF4's amino acid residue glutamate 302 through 6, 7, and 18 hydroxyl bands. Our findings demonstrated that Ori prevented metabolic activation of APAP and further inhibited the ATF4/PGC-1α pathway to alleviate APAP overdose-induced hepatic toxicity, which illuminated its potential therapeutic effects on ALI.
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Affiliation(s)
- Dongsheng Yu
- Department of Chinese Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Jiye Li
- Henan Research Centre for Organ Transplantation, Zhengzhou, China.,Henan Key Laboratory for Digestive Organ Transplantation, Zhengzhou, China
| | - Yu Wang
- Department of Chinese Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Danfeng Guo
- Henan Research Centre for Organ Transplantation, Zhengzhou, China.,Henan Key Laboratory for Digestive Organ Transplantation, Zhengzhou, China
| | - Xiaodan Zhang
- Henan Research Centre for Organ Transplantation, Zhengzhou, China.,Henan Key Laboratory for Digestive Organ Transplantation, Zhengzhou, China
| | - Mingming Chen
- Chinese Medicine Modernization and Big Data Research Center, Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine, Nanjing, China.,Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Zheng Zhou
- Department of Chinese Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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14
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Huang CY, Chen HW, Lo CW, Wang YR, Li CC, Liu KL, Lii CK. Luteolin ameliorates palmitate-induced lipotoxicity in hepatocytes by mediating endoplasmic reticulum stress and autophagy. Food Chem Toxicol 2022; 171:113554. [PMID: 36509263 DOI: 10.1016/j.fct.2022.113554] [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: 07/12/2022] [Revised: 11/21/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
Abnormal accumulation of lipids in liver leads to uncontrolled endoplasmic reticulum (ER) stress and autophagy. Luteolin is known to have antioxidant, anti-inflammatory, and anti-cancer properties, but whether it protects against lipotoxicity in liver remains unclear. In this study, we challenged AML12 liver cells and mouse primary hepatocytes with palmitic acid (PA) with or without luteolin pretreatment. In the presence of PA, reactive oxygen species (ROS) production was increased at 3 h, followed by enhancement of expression of p-PERK, ATF4, p-eIF2α, CHOP, and TXNIP (ER stress markers) and p-p62 and LC3II/LC3I ratio (autophagy markers), in both primary hepatocytes and AML12 cells. When PA treatment was extended up to 24 h, apoptosis was induced as evidenced by an increase in caspase-3 activation. RFP-GFP-LC3B transfection further revealed that the fusion of autophagosomes with lysosomes was damaged by PA. With luteolin treatment, the expression of antioxidant enzymes, i.e., heme oxygenase-1 and glutathione peroxidase, was upregulated, and PA-induced ROS production, ER stress, and cell death were dose-dependently ameliorated. Luteolin could also reverse the damage caused to autophagic flux. These results indicate that luteolin protects hepatocytes against PA assault by enhancing antioxidant defense, which can attenuate ER stress and autophagy as well as promote autophagic flux.
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Affiliation(s)
- Chun-Yin Huang
- Department of Nutrition, China Medical University, Taichung, Taiwan
| | - Haw-Wen Chen
- Department of Nutrition, China Medical University, Taichung, Taiwan
| | - Chia-Wen Lo
- Department of Nutrition, China Medical University, Taichung, Taiwan
| | - Yu-Ru Wang
- Department of Nutrition, China Medical University, Taichung, Taiwan
| | - Chien-Chun Li
- Department of Nutrition, Chung Shan Medical University, Taichung, Taiwan; Department of Nutrition, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Kai-Li Liu
- Department of Nutrition, Chung Shan Medical University, Taichung, Taiwan; Department of Nutrition, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Chong-Kuei Lii
- Department of Nutrition, China Medical University, Taichung, Taiwan; Department of Health and Nutrition Biotechnology, Asia University, Taichung, Taiwan.
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15
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Steffen J, Ngo J, Wang SP, Williams K, Kramer HF, Ho G, Rodriguez C, Yekkala K, Amuzie C, Bialecki R, Norquay L, Nawrocki AR, Erion M, Pocai A, Shirihai OS, Liesa M. The mitochondrial fission protein Drp1 in liver is required to mitigate NASH and prevents the activation of the mitochondrial ISR. Mol Metab 2022; 64:101566. [PMID: 35940556 PMCID: PMC9420962 DOI: 10.1016/j.molmet.2022.101566] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 07/14/2022] [Accepted: 07/29/2022] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE The mitochondrial fission protein Drp1 was proposed to promote NAFLD, as inhibition of hepatocyte Drp1 early in life prevents liver steatosis induced by high-fat diet in mice. However, whether Drp1-knockdown in older mice can reverse established NASH is unknown. METHODS N-acetylgalactosamine-siRNA conjugates, an FDA approved method to deliver siRNA selectively to hepatocytes, were used to knockdown hepatocyte-Drp1 in mice (NAG-Drp1si). NASH was induced in C57BL/6NTac mice by Gubra-Amylin-NASH diet (D09100310, 40% fat, 22% fructose and 2% cholesterol) and treatment with NAG-Drp1si was started at week 24 of diet. Circulating transaminases, liver histology, gene expression of fibrosis and inflammation markers, and hydroxyproline synthesis determined NASH severity. Liver NEFA and triglycerides were quantified by GC/MS. Mitochondrial function was determined by respirometry. Western blots of Oma1, Opa1, p-eIf2α, as well as transcriptional analyses of Atf4-regulated genes determined ISR engagement. RESULTS NAG-Drp1si treatment decreased body weight and induced liver inflammation in adult healthy mice. Increased hepatic Gdf15 production was the major contributor to body-weight loss caused by NAG-Drp1si treatment, as Gdf15 receptor deletion (Gfral KO) prevented the decrease in food intake and mitigated weight loss. NAG-Drp1si activated the Atf4-controlled integrated stress response (ISR) to increase hepatic Gdf15 expression. NAG-Drp1si in healthy mice caused ER stress and activated the mitochondrial protease Oma1, which are the ER and mitochondrial triggers that activate the Atf4-controlled ISR. Remarkably, induction of NASH was not sufficient to activate Oma1 in liver. However, NAG-Drp1si treatment was sufficient to activate Oma1 in adult mice with NASH, as well as exacerbating NASH-induced ER stress. Consequently, NAG-Drp1si treatment in mice with NASH led to higher ISR activation, exacerbated inflammation, fibrosis and necrosis. CONCLUSION Drp1 mitigates NASH by decreasing ER stress, preventing Oma1 activation and ISR exacerbation. The elevation in Gdf15 actions induced by NAG-Drp1si might represent an adaptive response decreasing the nutrient load to liver when mitochondria are misfunctional. Our study argues against blocking Drp1 in hepatocytes to combat NASH.
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Affiliation(s)
- Janos Steffen
- Cardiovascular and Metabolic Disease Research, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - Jennifer Ngo
- Department of Chemistry and Biochemistry, UCLA. 607 Charles E. Young Dr., Los Angeles, CA 90095, USA; Department of Medicine, Division of Endocrinology, David Geffen School of Medicine at UCLA. 650 Charles E. Young Dr., Los Angeles, CA 90095, USA
| | - Sheng-Ping Wang
- Cardiovascular and Metabolic Disease Research, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - Kevin Williams
- Department of Chemistry and Biochemistry, UCLA. 607 Charles E. Young Dr., Los Angeles, CA 90095, USA
| | - Henning F Kramer
- Cardiovascular and Metabolic Disease Research, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - George Ho
- Cardiovascular and Metabolic Disease Research, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - Carlos Rodriguez
- Cardiovascular and Metabolic Disease Research, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - Krishna Yekkala
- Preclinical Safety and Translational Sciences, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - Chidozie Amuzie
- Preclinical Safety and Translational Sciences, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - Russell Bialecki
- Preclinical Safety and Translational Sciences, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - Lisa Norquay
- Business Development, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - Andrea R Nawrocki
- Cardiovascular and Metabolic Disease Research, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - Mark Erion
- Cardiovascular and Metabolic Disease Research, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA
| | - Alessandro Pocai
- Cardiovascular and Metabolic Disease Research, Janssen Research & Development, LLC, 1400 McKean Road, Spring House, PA 19477-0776, USA.
| | - Orian S Shirihai
- Department of Medicine, Division of Endocrinology, David Geffen School of Medicine at UCLA. 650 Charles E. Young Dr., Los Angeles, CA 90095, USA; Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA. 650 Charles E. Young Dr., Los Angeles, CA 90095, USA.
| | - Marc Liesa
- Department of Medicine, Division of Endocrinology, David Geffen School of Medicine at UCLA. 650 Charles E. Young Dr., Los Angeles, CA 90095, USA; Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA. 650 Charles E. Young Dr., Los Angeles, CA 90095, USA; Molecular Biology Institute at UCLA, 611 Charles E. Young Drive East, Los Angeles, CA 90095-1570, USA; Institut de Biologia Molecular de Barcelona, IBMB, CSIC, Baldiri Reixac 4-8, Barcelona, Catalonia, 08028, Spain.
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16
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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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17
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Zhou L, Shen H, Li X, Wang H. Endoplasmic reticulum stress in innate immune cells - a significant contribution to non-alcoholic fatty liver disease. Front Immunol 2022; 13:951406. [PMID: 35958574 PMCID: PMC9361020 DOI: 10.3389/fimmu.2022.951406] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 06/28/2022] [Indexed: 12/12/2022] Open
Abstract
Liver disease and its complications affect millions of people worldwide. NAFLD (non-alcoholic fatty liver disease) is the liver disease associated with metabolic dysfunction and consists of four stages: steatosis with or without mild inflammation (NAFLD), non-alcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. With increased necroinflammation and progression of liver fibrosis, NAFLD may progress to cirrhosis or even hepatocellular carcinoma. Although the underlying mechanisms have not been clearly elucidated in detail, what is clear is that complex immune responses are involved in the pathogenesis of NASH, activation of the innate immune system is critically involved in triggering and amplifying hepatic inflammation and fibrosis in NAFLD/NASH. Additionally, disruption of endoplasmic reticulum (ER) homeostasis in cells, also known as ER stress, triggers the unfolded protein response (UPR) which has been shown to be involved to inflammation and apoptosis. To further develop the prevention and treatment of NAFLD/NASH, it is imperative to clarify the relationship between NAFLD/NASH and innate immune cells and ER stress. As such, this review focuses on innate immune cells and their ER stress in the occurrence of NAFLD and the progression of cirrhosis.
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Affiliation(s)
- Liangliang Zhou
- Department of Oncology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Medical University, Hefei, China
| | - Haiyuan Shen
- Department of Oncology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Medical University, Hefei, China
| | - Xiaofeng Li
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Medical University, Hefei, China
- Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China
| | - Hua Wang
- Department of Oncology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, Anhui Medical University, Hefei, China
- *Correspondence: Hua Wang,
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18
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Herrema H, Guan D, Choi JW, Feng X, Salazar Hernandez MA, Faruk F, Auen T, Boudett E, Tao R, Chun H, Ozcan U. FKBP11 rewires UPR signaling to promote glucose homeostasis in type 2 diabetes and obesity. Cell Metab 2022; 34:1004-1022.e8. [PMID: 35793654 DOI: 10.1016/j.cmet.2022.06.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 11/21/2021] [Accepted: 06/11/2022] [Indexed: 12/12/2022]
Abstract
Chronic endoplasmic reticulum (ER) stress and sustained activation of unfolded protein response (UPR) signaling contribute to the development of type 2 diabetes in obesity. UPR signaling is a complex signaling pathway, which is still being explored in many different cellular processes. Here, we demonstrate that FK506-binding protein 11 (FKBP11), which is transcriptionally regulated by XBP1s, is severely reduced in the livers of obese mice. Restoring hepatic FKBP11 expression in obese mice initiates an atypical UPR signaling pathway marked by rewiring of PERK signaling toward NRF2, away from the eIF2α-ATF4 axis of the UPR. This alteration in UPR signaling establishes glucose homeostasis without changing hepatic ER stress, food consumption, or body weight. We conclude that ER stress during obesity can be beneficially rewired to promote glucose homeostasis. These findings may uncover possible new avenues in the development of novel approaches to treat diseases marked by ER stress.
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Affiliation(s)
- Hilde Herrema
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02130, USA.
| | - Dongxian Guan
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02130, USA
| | - Jae Won Choi
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02130, USA
| | - Xudong Feng
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02130, USA
| | | | - Farhana Faruk
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02130, USA
| | - Thomas Auen
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02130, USA
| | - Eliza Boudett
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02130, USA
| | - Rongya Tao
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02130, USA
| | - Hyonho Chun
- Department of Mathematics and Statistics, Boston University, Boston, MA 02130, USA
| | - Umut Ozcan
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02130, USA.
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19
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Byun JH, Lebeau PF, Platko K, Carlisle RE, Faiyaz M, Chen J, MacDonald ME, Makda Y, Yousof T, Lynn EG, Dickhout JG, Krepinsky JC, Weaver F, Igdoura SA, Seidah NG, Austin RC. Inhibitory Antibodies against PCSK9 Reduce Surface CD36 and Mitigate Diet-Induced Renal Lipotoxicity. KIDNEY360 2022; 3:1394-1410. [PMID: 36176646 PMCID: PMC9416829 DOI: 10.34067/kid.0007022021] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 04/26/2022] [Indexed: 01/11/2023]
Abstract
Background PCSK9 modulates the uptake of circulating lipids through a range of receptors, including the low-density lipoprotein receptor (LDLR) and CD36. In the kidney, CD36 is known to contribute to renal injury through pro-inflammatory and -fibrotic pathways. In this study, we sought to investigate the role of PCSK9 in modulating renal lipid accumulation and injury through CD36 using a high fat diet (HFD)-induced murine model. Methods The effect of PCSK9 on the expression of CD36 and intracellular accumulation of lipid was examined in cultured renal cells and in the kidneys of male C57BL/6J mice. The effect of these findings was subsequently explored in a model of HFD-induced renal injury in Pcsk9 -/- and Pcsk9 +/+ littermate control mice on a C57BL/6J background. Results In the absence of PCSK9, we observed heightened CD36 expression levels, which increased free fatty acid (FFA) uptake in cultured renal tubular cells. As a result, PCSK9 deficiency was associated with an increase in long-chain saturated FFA-induced ER stress. Consistent with these observations, Pcsk9-/- mice fed a HFD displayed elevated ER stress, inflammation, fibrosis, and renal injury relative to HFD-fed control mice. In contrast to Pcsk9-/- mice, pretreatment of WT C57BL/6J mice with evolocumab, an anti-PCSK9 monoclonal antibody (mAb) that binds to and inhibits the function of circulating PCSK9, protected against HFD-induced renal injury in association with reducing cell surface CD36 expression on renal epithelia. Conclusions We report that circulating PCSK9 modulates renal lipid uptake in a manner dependent on renal CD36. In the context of increased dietary fat consumption, the absence of circulating PCSK9 may promote renal lipid accumulation and subsequent renal injury. However, although the administration of evolocumab blocks the interaction of PCSK9 with the LDLR, this evolocumab/PCSK9 complex can still bind CD36, thereby protecting against HFD-induced renal lipotoxicity.
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Affiliation(s)
- Jae Hyun Byun
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Paul F. Lebeau
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Khrystyna Platko
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Rachel E. Carlisle
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Mahi Faiyaz
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Jack Chen
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Melissa E. MacDonald
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Yumna Makda
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Tamana Yousof
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Edward G. Lynn
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Jeffrey G. Dickhout
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Joan C. Krepinsky
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
| | - Fiona Weaver
- Department of Biology and Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
| | - Suleiman A. Igdoura
- Department of Biology and Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
| | - Nabil G. Seidah
- Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, University of Montreal, Montreal, Canada
| | - Richard C. Austin
- Department of Medicine, Division of Nephrology, McMaster University, The Research Institute of St. Joe’s Hamilton and The Hamilton Centre for Kidney Research, Hamilton, Canada
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20
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Malekpour-Dehkordi Z, Nourbakhsh M, Shahidi M, Sarraf N, Sharifi R. "Silymarin diminishes oleic acid-induced lipid accumulation in HepG2 cells by modulating the expression of endoplasmic reticulum stress markers". J Herb Med 2022. [DOI: 10.1016/j.hermed.2022.100565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Duwaerts CC, Maiers JL. ER Disposal Pathways in Chronic Liver Disease: Protective, Pathogenic, and Potential Therapeutic Targets. Front Mol Biosci 2022; 8:804097. [PMID: 35174209 PMCID: PMC8841999 DOI: 10.3389/fmolb.2021.804097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 11/18/2021] [Indexed: 11/13/2022] Open
Abstract
The endoplasmic reticulum is a central player in liver pathophysiology. Chronic injury to the ER through increased lipid content, alcohol metabolism, or accumulation of misfolded proteins causes ER stress, dysregulated hepatocyte function, inflammation, and worsened disease pathogenesis. A key adaptation of the ER to resolve stress is the removal of excess or misfolded proteins. Degradation of intra-luminal or ER membrane proteins occurs through distinct mechanisms that include ER-associated Degradation (ERAD) and ER-to-lysosome-associated degradation (ERLAD), which includes macro-ER-phagy, micro-ER-phagy, and Atg8/LC-3-dependent vesicular delivery. All three of these processes are critical for removing misfolded or unfolded protein aggregates, and re-establishing ER homeostasis following expansion/stress, which is critical for liver function and adaptation to injury. Despite playing a key role in resolving ER stress, the contribution of these degradative processes to liver physiology and pathophysiology is understudied. Analysis of publicly available datasets from diseased livers revealed that numerous genes involved in ER-related degradative pathways are dysregulated; however, their roles and regulation in disease progression are not well defined. Here we discuss the dynamic regulation of ER-related protein disposal pathways in chronic liver disease and cell-type specific roles, as well as potentially targetable mechanisms for treatment of chronic liver disease.
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Affiliation(s)
- Caroline C. Duwaerts
- Department of Medicine, University of California, San Francisco, San Francisco, CA, United States
| | - Jessica L. Maiers
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States
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22
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Park CY, Lee SK, Kim J, Kim D, Choe H, Jeong JH, Choi KC, Park HS, Han SN, Jang YJ. Endoplasmic reticulum stress increases LECT2 expression via ATF4. Biochem Biophys Res Commun 2021; 585:169-176. [PMID: 34808500 DOI: 10.1016/j.bbrc.2021.11.038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 11/11/2021] [Indexed: 12/23/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is frequently associated with obesity, insulin resistance, and endoplasmic reticulum (ER) stress. Elevated circulating levels of the hepatokine leukocyte cell-derived chemotaxin-2 (LECT2) have also been noted in NAFLD; however, the mechanism underlying this association is unclear. To investigate a possible link between ER stress/unfolded protein response (UPR) signaling and LECT2 secretion, HepG2 cells were incubated with ER stress inducers with or without an ER stress-reducing chemical chaperone. Additionally, UPR pathway genes were knocked down and overexpressed, and a ChIP assay was performed. In diet-induced obese mice, hepatic expression of LECT2 and activating transcription factor 4 (ATF4) was measured. In HepG2 cells, LECT2 expression was increased by ER stressors, an effect blocked by the chemical chaperone. Among UPR pathway proteins, only knockdown of ATF4 suppressed ER stress-induced LECT2 expression, while overexpression of ATF4 enhanced LECT2 expression. The ChIP assay revealed that ATF4 binds to three putative binding sites on the LECT2 promoter and binding is promoted by an ER stress inducer. In steatotic livers of obese mice, LECT2 and ATF4 expression was concomitantly elevated. Our data indicate that activation of ER stress/UPR signaling induces LECT2 expression in steatotic liver; specifically, ATF4 appears to mediate upregulation of LECT2 transcription.
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Affiliation(s)
- Chan Yoon Park
- Department of Physiology, University of Ulsan College of Medicine, Seoul, South Korea; Department of Food & Nutrition, College of Health Science, The University of Suwon, Hwaseong-si, Gyeonggi-do, South Korea
| | - Seul Ki Lee
- Department of Physiology, University of Ulsan College of Medicine, Seoul, South Korea
| | - Jimin Kim
- Department of Physiology, University of Ulsan College of Medicine, Seoul, South Korea
| | - Donguk Kim
- Department of Physiology, University of Ulsan College of Medicine, Seoul, South Korea
| | - Han Choe
- Department of Physiology, University of Ulsan College of Medicine, Seoul, South Korea
| | - Ji-Hoon Jeong
- Department of Biomedical Sciences, Asan Medical Center, AMIST, University of Ulsan College of Medicine, Seoul, South Korea
| | - Kyung-Chul Choi
- Department of Biomedical Sciences, Asan Medical Center, AMIST, University of Ulsan College of Medicine, Seoul, South Korea
| | - Hye Soon Park
- Department of Family Medicine, University of Ulsan College of Medicine, Seoul, South Korea
| | - Sung Nim Han
- Department of Food and Nutrition & Research Institute of Human Ecology, College of Human Ecology, Seoul National University, Seoul, South Korea
| | - Yeon Jin Jang
- Department of Physiology, University of Ulsan College of Medicine, Seoul, South Korea.
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23
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Byles V, Cormerais Y, Kalafut K, Barrera V, Hughes Hallett JE, Sui SH, Asara JM, Adams CM, Hoxhaj G, Ben-Sahra I, Manning BD. Hepatic mTORC1 signaling activates ATF4 as part of its metabolic response to feeding and insulin. Mol Metab 2021; 53:101309. [PMID: 34303878 PMCID: PMC8368025 DOI: 10.1016/j.molmet.2021.101309] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 07/14/2021] [Accepted: 07/19/2021] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVE The mechanistic target of rapamycin complex 1 (mTORC1) is dynamically regulated by fasting and feeding cycles in the liver to promote protein and lipid synthesis while suppressing autophagy. However, beyond these functions, the metabolic response of the liver to feeding and insulin signaling orchestrated by mTORC1 remains poorly defined. Here, we determine whether ATF4, a stress responsive transcription factor recently found to be independently regulated by mTORC1 signaling in proliferating cells, is responsive to hepatic mTORC1 signaling to alter hepatocyte metabolism. METHODS ATF4 protein levels and expression of canonical gene targets were analyzed in the liver following fasting and physiological feeding in the presence or absence of the mTORC1 inhibitor, rapamycin. Primary hepatocytes from wild-type or liver-specific Atf4 knockout (LAtf4KO) mice were used to characterize the effects of insulin-stimulated mTORC1-ATF4 function on hepatocyte gene expression and metabolism. Both unbiased steady-state metabolomics and stable-isotope tracing methods were employed to define mTORC1 and ATF4-dependent metabolic changes. RNA-sequencing was used to determine global changes in feeding-induced transcripts in the livers of wild-type versus LAtf4KO mice. RESULTS We demonstrate that ATF4 and its metabolic gene targets are stimulated by mTORC1 signaling in the liver, in a hepatocyte-intrinsic manner by insulin in response to feeding. While we demonstrate that de novo purine and pyrimidine synthesis is stimulated by insulin through mTORC1 signaling in primary hepatocytes, this regulation was independent of ATF4. Metabolomics and metabolite tracing studies revealed that insulin-mTORC1-ATF4 signaling stimulates pathways of nonessential amino acid synthesis in primary hepatocytes, including those of alanine, aspartate, methionine, and cysteine, but not serine. CONCLUSIONS The results demonstrate that ATF4 is a novel metabolic effector of mTORC1 in the liver, extending the molecular consequences of feeding and insulin-induced mTORC1 signaling in this key metabolic tissue to the control of amino acid metabolism.
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Affiliation(s)
- Vanessa Byles
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Yann Cormerais
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Krystle Kalafut
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Victor Barrera
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - James E Hughes Hallett
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Shannan Ho Sui
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - John M Asara
- Division of Signal Transduction, Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Christopher M Adams
- Division of Endocrinology, Metabolism and Nutrition, Mayo Clinic, Rochester, MN, USA
| | - Gerta Hoxhaj
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA; Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Issam Ben-Sahra
- Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine and Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL, USA
| | - Brendan D Manning
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
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24
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Mizuno TM, Lew PS. Regulation of Activating Transcription Factor 4 (ATF4) Expression by Fat Mass and Obesity-Associated (FTO) in Mouse Hepatocyte Cells. ACTA ENDOCRINOLOGICA-BUCHAREST 2021; 17:26-32. [PMID: 34539907 DOI: 10.4183/aeb.2021.26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Context Abnormally increased hepatic glucose production contributes to hyperglycemia in diabetes. Interventions that suppress hepatic gluconeogenesis should be beneficial in improving glycemic control in patients with diabetes. Objectives It has been suggested that hepatic FTO is involved in glycemic control by regulating gluconeogenesis. Both FTO and activating transcription factor 4 (ATF4) positively regulate the expression of gluconeogenic genes in the liver, suggesting the possibility that ATF4 mediates the stimulatory effect of FTO on hepatic gluconeogenesis. The present study aimed to determine the effect of altered expression or activity of FTO on Atf4 and gluconeogenic gene expression in hepatocyte cells. Methods Mouse hepatocyte AML12 cells were treated with the FTO inhibitor rhein or transfected with an FTO-expressing plasmid. Levels of gluconeogenic glucose-6-phosphatase (G6pc) and Atf4 mRNA and protein were measured. Results Rhein treatment significantly reduced G6pc mRNA levels as well as Atf4 mRNA and protein levels. Conversely, enhanced FTO expression caused an increase in G6pc and Atf4 mRNA levels. Conclusions These findings support the hypothesis that hepatic FTO participates in the regulation of hepatic gluconeogenic gene and ATF4 expression. Reducing the activity of the hepatic FTO-ATF4 pathway may be beneficial in reducing hepatic glucose production and ameliorating hyperglycemia in diabetes.
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Affiliation(s)
- T M Mizuno
- University of Manitoba, Department of Physiology and Pathophysiology, Winnipeg, Manitoba, Canada
| | - P S Lew
- University of Manitoba, Department of Physiology and Pathophysiology, Winnipeg, Manitoba, Canada
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25
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Dong XC, Chowdhury K, Huang M, Kim HG. Signal Transduction and Molecular Regulation in Fatty Liver Disease. Antioxid Redox Signal 2021; 35:689-717. [PMID: 33906425 PMCID: PMC8558079 DOI: 10.1089/ars.2021.0076] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Significance: Fatty liver disease is a major liver disorder in the modern societies. Comprehensive understanding of the pathophysiology and molecular mechanisms is essential for the prevention and treatment of the disease. Recent Advances: Remarkable progress has been made in the recent years in basic and translational research in the field of fatty liver disease. Multiple signaling pathways have been implicated in the development of fatty liver disease, including AMP-activated protein kinase, mechanistic target of rapamycin kinase, endoplasmic reticulum stress, oxidative stress, inflammation, transforming growth factor β, and yes1-associated transcriptional regulator/transcriptional coactivator with PDZ-binding motif (YAP/TAZ). In addition, critical molecular regulations at the transcriptional and epigenetic levels have been linked to the pathogenesis of fatty liver disease. Critical Issues: Some critical issues remain to be solved so that research findings can be translated into clinical applications. Robust and reliable biomarkers are needed for diagnosis of different stages of the fatty liver disease. Effective and safe molecular targets remain to be identified and validated. Prevention strategies require solid scientific evidence and population-wide feasibility. Future Directions: As more data are generated with time, integrative approaches are needed to comprehensively understand the disease pathophysiology and mechanisms at multiple levels from population, organismal system, organ/tissue, to cell. The interactions between genes and environmental factors require deeper investigation for the purposes of prevention and personalized treatment of fatty liver disease. Antioxid. Redox Signal. 35, 689-717.
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Affiliation(s)
- Xiaocheng Charlie Dong
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of BioHealth Informatics, School of Informatics and Computing, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, USA
| | - Kushan Chowdhury
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Menghao Huang
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Hyeong Geug Kim
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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26
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Cheng S, Liu X, Gong F, Ding X, Zhou X, Liu C, Zhao F, Li X, Shi J. Dexamethasone promotes the endoplasmic reticulum stress response of bone marrow mesenchymal stem cells by activating the PERK-Nrf2 signaling pathway. Pharmacol Res Perspect 2021; 9:e00791. [PMID: 34038621 PMCID: PMC8153378 DOI: 10.1002/prp2.791] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 04/19/2021] [Indexed: 12/20/2022] Open
Abstract
The pathogenesis of steroid-induced avascular necrosis of femoral head (SANFH) is complex, and there is a lack of effective early prevention method. The aim of the present study was to evaluate the effect of dexamethasone (DEX) on the biological behavior of bone marrow mesenchymal stem cells (BMSCs) and to explore the possibility of DEX in the clinical treatment of SANFH. The effect of DEX on the proliferation of BMSCs was evaluated by Counting Kit-8 assay, western blot assay, and enzyme-linked immunosorbent assay. Flow cytometry and western blot assay were performed to detect the effect of DEX on the apoptosis of BMSCs. Quantitative real-time PCR and western blot assay were performed to detect the effect of DEX on the expression of endoplasmic reticulum stress (ERS)-related genes. Immunoblotting analysis was conducted for detecting the nuclear-cytoplasmic distribution of Nrf2. DEX could significantly inhibit the proliferation of BMSCs and promote apoptosis of BMSCs. DEX could increase the expression of PERK, ATF6, and IRE1a, and induce nuclear translocation of Nrf2. The addition of ML385 could reverse the effect of DEX on BMSCs. DEX could activate the PERK-Nrf2 pathway to promote ERS and finally affect the cell proliferation and apoptosis of BMSCs.
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Affiliation(s)
- Suoli Cheng
- Department of Orthopaedics, Ningxia Medical University, People's Hospital of Ningxia Hui Autonomous Region, Yinchuan, Ningxia, China
| | - Xueqin Liu
- Department of Obstetrics and Gynecology, People's Hospital of Ningxia Hui Autonomous Region, Yinchuan, Ningxia, China
| | - Fan Gong
- Department of Orthopaedics, People's Hospital of Ningxia Hui Autonomous Region, Yinchuan, Ningxia, China
| | - Xiaoling Ding
- Department of Digestive System, People's Hospital of Ningxia Hui Autonomous Region, Yinchuan, Ningxia, China
| | - Xuebing Zhou
- Department of General Surgery, People's Hospital of Ningxia Hui Autonomous Region, Yinchuan, Ningxia, China
| | - Cuiyun Liu
- Department of Pediatrics, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, China
| | - Fei Zhao
- Department of Orthopaedics, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, China
| | - Xiaoliang Li
- Department of Orthopaedics, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, China
| | - Jiandang Shi
- Department of Orthopaedics, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, China
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27
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Cui A, Ding D, Li Y. Regulation of Hepatic Metabolism and Cell Growth by the ATF/CREB Family of Transcription Factors. Diabetes 2021; 70:653-664. [PMID: 33608424 PMCID: PMC7897342 DOI: 10.2337/dbi20-0006] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/14/2020] [Indexed: 12/12/2022]
Abstract
The liver is a major metabolic organ that regulates the whole-body metabolic homeostasis and controls hepatocyte proliferation and growth. The ATF/CREB family of transcription factors integrates nutritional and growth signals to the regulation of metabolism and cell growth in the liver, and deregulated ATF/CREB family signaling is implicated in the progression of type 2 diabetes, nonalcoholic fatty liver disease, and cancer. This article focuses on the roles of the ATF/CREB family in the regulation of glucose and lipid metabolism and cell growth and its importance in liver physiology. We also highlight how the disrupted ATF/CREB network contributes to human diseases and discuss the perspectives of therapeutically targeting ATF/CREB members in the clinic.
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Affiliation(s)
- Aoyuan Cui
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Dong Ding
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yu Li
- CAS Key Laboratory of Nutrition, Metabolism and Food Safety, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
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28
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Wei J, Fang D. Endoplasmic Reticulum Stress Signaling and the Pathogenesis of Hepatocarcinoma. Int J Mol Sci 2021; 22:ijms22041799. [PMID: 33670323 PMCID: PMC7918477 DOI: 10.3390/ijms22041799] [Citation(s) in RCA: 170] [Impact Index Per Article: 56.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 12/12/2022] Open
Abstract
Hepatocellular carcinoma (HCC), also known as hepatoma, is a primary malignancy of the liver and the third leading cause of cancer mortality globally. Although much attention has focused on HCC, its pathogenesis remains largely obscure. The endoplasmic reticulum (ER) is a cellular organelle important for regulating protein synthesis, folding, modification and trafficking, and lipid metabolism. ER stress occurs when ER homeostasis is disturbed by numerous environmental, physiological, and pathological challenges. In response to ER stress due to misfolded/unfolded protein accumulation, unfolded protein response (UPR) is activated to maintain ER function for cell survival or, in cases of excessively severe ER stress, initiation of apoptosis. The liver is especially susceptible to ER stress given its protein synthesis and detoxification functions. Experimental data suggest that ER stress and unfolded protein response are involved in HCC development, aggressiveness and response to treatment. Herein, we highlight recent findings and provide an overview of the evidence linking ER stress to the pathogenesis of HCC.
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29
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Moncan M, Mnich K, Blomme A, Almanza A, Samali A, Gorman AM. Regulation of lipid metabolism by the unfolded protein response. J Cell Mol Med 2021; 25:1359-1370. [PMID: 33398919 PMCID: PMC7875919 DOI: 10.1111/jcmm.16255] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 12/17/2022] Open
Abstract
The endoplasmic reticulum (ER) is the site of protein folding and secretion, Ca2+ storage and lipid synthesis in eukaryotic cells. Disruption to protein folding or Ca2+ homeostasis in the ER leads to the accumulation of unfolded proteins, a condition known as ER stress. This leads to activation of the unfolded protein response (UPR) pathway in order to restore protein homeostasis. Three ER membrane proteins, namely inositol‐requiring enzyme 1 (IRE1), protein kinase RNA‐like ER kinase (PERK) and activating transcription factor 6 (ATF6), sense the accumulation of unfolded/misfolded proteins and are activated, initiating an integrated transcriptional programme. Recent literature demonstrates that activation of these sensors can alter lipid enzymes, thus implicating the UPR in the regulation of lipid metabolism. Given the presence of ER stress and UPR activation in several diseases including cancer and neurodegenerative diseases, as well as the growing recognition of altered lipid metabolism in disease, it is timely to consider the role of the UPR in the regulation of lipid metabolism. This review provides an overview of the current knowledge on the impact of the three arms of the UPR on the synthesis, function and regulation of fatty acids, triglycerides, phospholipids and cholesterol.
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Affiliation(s)
- Matthieu Moncan
- Apoptosis Research Centre, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Katarzyna Mnich
- Apoptosis Research Centre, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Arnaud Blomme
- Laboratory of Cancer Signaling, GIGA-institute, University of Liège, Liège, Belgium
| | - Aitor Almanza
- Apoptosis Research Centre, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Afshin Samali
- Apoptosis Research Centre, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Adrienne M Gorman
- Apoptosis Research Centre, School of Natural Sciences, National University of Ireland, Galway, Ireland
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30
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Abstract
Nonalcoholic hepatitis (NASH) is the progressive inflammatory form of nonalcoholic fatty liver disease. Although the mechanisms of hepatic inflammation in NASH remain incompletely understood, emerging literature implicates the proinflammatory environment created by toxic lipid-induced hepatocyte injury, termed lipotoxicity. Interestingly, numerous NASH-promoting kinases in hepatocytes, immune cells, and adipocytes are activated by the lipotoxic insult associated with obesity. In the current review, we discuss recent advances in NASH-promoting kinases as disease mediators and therapeutic targets. The focus of the review is mainly on the mitogen-activated protein kinases including mixed lineage kinase 3, apoptosis signal-regulating kinase 1, c-Jun N-terminal kinase, and p38 MAPK; the endoplasmic reticulum (ER) stress kinases protein kinase RNA-like ER kinase and inositol-requiring protein-1α; as well as the Rho-associated protein kinase 1. We also discuss various pharmacological agents targeting these stress kinases in NASH that are under different phases of development.
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Affiliation(s)
- Samar H. Ibrahim
- Division of Gastroenterology & Hepatology in the Department of Pediatrics, Rochester, Minnesota.,Division of Gastroenterology & Hepatology in the Department of Medicine Mayo Clinic, Rochester, Minnesota
| | - Petra Hirsova
- Division of Gastroenterology & Hepatology in the Department of Medicine Mayo Clinic, Rochester, Minnesota
| | - Harmeet Malhi
- Division of Gastroenterology & Hepatology in the Department of Medicine Mayo Clinic, Rochester, Minnesota
| | - Gregory J. Gores
- Division of Gastroenterology & Hepatology in the Department of Medicine Mayo Clinic, Rochester, Minnesota
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31
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Nathanael J, Harsono HCA, Wibawa AD, Suardana P, Vianney YM, Dwi Putra SE. The genetic basis of high-carbohydrate and high-monosodium glutamate diet related to the increase of likelihood of type 2 diabetes mellitus: a review. Endocrine 2020; 69:18-29. [PMID: 32172486 DOI: 10.1007/s12020-020-02256-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 03/03/2020] [Indexed: 12/27/2022]
Abstract
Diabetes is one of the most common metabolic diseases. Aside from the genetic factor, previous studies stated that other factors such as environment, lifestyle, and paternal-maternal condition play critical roles in diabetes through DNA methylation in specific areas of the genome. One of diabetic cases is caused by insulin resistance and changing the homeostasis of blood glucose control so glucose concentration stood beyond normal rate (hyperglycemia). High fat diet has been frequently studied and linked to triggering diabetes. However, most Asians consume rice (or food with high carbohydrate) and food with monosodium glutamate (MSG). This habit could lead to pathophysiology of type 2 diabetes mellitus (T2D). Previous studies showed that high-carbohydrate or high-MSG diet could change gene expression or modify protein activity in body metabolism. This imbalanced metabolism can lead to pleiotropic effects of diabetes mellitus. In this study, the authors have attempted to relate various changes in genes expression or protein activity to the high-carbohydrate and high-MSG-induced diabetes. The authors have also tried to relate several genes that contribute to pathophysiology of T2D and proposed several ideas of genes as markers and target for curing people with T2D. These are done by investigating altered activities of various genes that cause or are caused by diabetes. These genes are selected based on their roles in pathophysiology of T2D.
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Affiliation(s)
- Joshua Nathanael
- Department of Biology, Faculty of Biotechnology, University of Surabaya, Raya Kalirungkut, Surabaya, East Java, 60292, Indonesia
| | - Hans Cristian Adhinatya Harsono
- Department of Biology, Faculty of Biotechnology, University of Surabaya, Raya Kalirungkut, Surabaya, East Java, 60292, Indonesia
| | - Aubrey Druce Wibawa
- Department of Biology, Faculty of Biotechnology, University of Surabaya, Raya Kalirungkut, Surabaya, East Java, 60292, Indonesia
| | - Putu Suardana
- Department of Biology, Faculty of Biotechnology, University of Surabaya, Raya Kalirungkut, Surabaya, East Java, 60292, Indonesia
| | - Yoanes Maria Vianney
- Department of Biology, Faculty of Biotechnology, University of Surabaya, Raya Kalirungkut, Surabaya, East Java, 60292, Indonesia
| | - Sulistyo Emantoko Dwi Putra
- Department of Biology, Faculty of Biotechnology, University of Surabaya, Raya Kalirungkut, Surabaya, East Java, 60292, Indonesia.
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32
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Do MH, Lee HB, Lee E, Park HY. The Effects of Gelatinized Wheat Starch and High Salt Diet on Gut Microbiota and Metabolic Disorder. Nutrients 2020; 12:E301. [PMID: 31979147 PMCID: PMC7070891 DOI: 10.3390/nu12020301] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 01/17/2020] [Accepted: 01/19/2020] [Indexed: 02/07/2023] Open
Abstract
Diets high in gelatinized starch and high in gelatinized starch supplemented with salt-induced metabolic disorders and changes in gut microbiota have scarcely been studied. In this study, mice on wheat starch diets (WD) exhibited significantly higher body weight, white adipose tissue (WAT), and gut permeability compared to those on normal diet (ND). However, gelatinized wheat starch diet (GWD) and NaCl-supplemented gelatinized wheat starch diet (SGW) mice did not increase body and WAT weights or dyslipidemia, and maintained consistent colon pH at ND levels. WD mice showed higher levels of Desulfovibrio, Faecalibaculum, and Lactobacillus and lower levels of Muribaculum compared to ND mice. However, GWD and SGW mice showed a significantly different gut microbial composition, such as a lower proportion of Lactobacillus and Desulfovibrio, and higher proportion of Faecalibaculum and Muribaculum compared to WD mice. High starch diet-induced dysbiosis caused increase of lipid accumulation and inflammation-related proteins' expression, thereby leading to non-alcoholic fatty liver disease. However, GWD and SGW showed lower levels than that, and it might be due to the difference in the gut microbial composition compared to WD. Taken together, diets high in gelatinized starch and high in gelatinized starch supplemented with salt induced mild metabolic disorders compared to native starch.
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Affiliation(s)
- Moon Ho Do
- Research Division of Food Functionality, Korea Food Research Institute, Jeollabuk-do 55365, Korea; (M.H.D.); (H.-B.L.)
| | - Hye-Bin Lee
- Research Division of Food Functionality, Korea Food Research Institute, Jeollabuk-do 55365, Korea; (M.H.D.); (H.-B.L.)
- Department of Food Science and Technology, Chonbuk National University, Jeollabuk-do 54896, Korea
| | - Eunjung Lee
- Research Division of Strategic Food Technology, Korea Food Research Institute, Jeollabuk-do 55365, Korea;
| | - Ho-Young Park
- Research Division of Food Functionality, Korea Food Research Institute, Jeollabuk-do 55365, Korea; (M.H.D.); (H.-B.L.)
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Song MJ, Malhi H. The unfolded protein response and hepatic lipid metabolism in non alcoholic fatty liver disease. Pharmacol Ther 2019; 203:107401. [PMID: 31419516 PMCID: PMC6848795 DOI: 10.1016/j.pharmthera.2019.107401] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 08/08/2019] [Indexed: 12/19/2022]
Abstract
Nonalcoholic fatty liver disease is a major public health burden. Although many features of nonalcoholic fatty liver disease pathogenesis are known, the specific mechanisms and susceptibilities that determine an individual's risk of developing nonalcoholic steatohepatitis versus isolated steatosis are not well delineated. The predominant and defining histologic and imaging characteristic of nonalcoholic fatty liver disease is the accumulation of lipids. Dysregulation of lipid homeostasis in hepatocytes leads to transient generation or accumulation of toxic lipids that result in endoplasmic reticulum (ER) stress with inflammation, hepatocellular damage, and apoptosis. ER stress activates the unfolded protein response (UPR) which is classically viewed as an adaptive pathway to maintain protein folding homeostasis. Recent studies have uncovered the contribution of the UPR sensors in the regulation of hepatic steatosis and in the cellular response to lipotoxic stress. Interestingly, the UPR sensors can be directly activated by toxic lipids, independently of the accumulation of misfolded proteins, termed lipotoxic and proteotoxic stress, respectively. The dual function of the UPR sensors in protein and lipid homeostasis suggests that these two types of stress are interconnected likely due to the central role of the ER in protein folding and trafficking and lipid biosynthesis and trafficking, such that perturbations in either impact the function of the ER and activate the UPR sensors in an effort to restore homeostasis. The precise molecular similarities and differences between proteotoxic and lipotoxic ER stress are beginning to be understood. Herein, we provide an overview of the mechanisms involved in the activation and cross-talk between the UPR sensors, hepatic lipid metabolism, and lipotoxic stress, and discuss the possible therapeutic potential of targeting the UPR in nonalcoholic fatty liver disease.
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Affiliation(s)
- Myeong Jun Song
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, United States of America; Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea
| | - Harmeet Malhi
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, United States of America.
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Ma Y, Zhang M, Yu H, Lu J, Cheng KKY, Zhou J, Chen H, Jia W. Activation of G0/G1 switch gene 2 by endoplasmic reticulum stress enhances hepatic steatosis. Metabolism 2019; 99:32-44. [PMID: 31271806 DOI: 10.1016/j.metabol.2019.06.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 06/12/2019] [Accepted: 06/28/2019] [Indexed: 12/27/2022]
Abstract
BACKGROUND Perturbed endoplasmic reticulum (ER) homeostasis and increased levels of G0/G1 Switch Gene 2 (G0S2) have been documented in animal models with fatty liver disease. In this study, we investigated whether G0S2 is regulated by branch of the unfolded protein response (UPR) and contributes to ER stress-induced hepatic steatosis. METHODS We first analyzed G0S2 expression and the state of the three canonical UPR branches in several hepatic steatosis models, tunicamycin-treated C57BL/6J mice and HepG2 cells, where ER homeostasis was perturbed. We pretreated HepG2 cells with tauroursodeoxycholic acid (TUDCA) to validate whether G0S2 was the downstream target of ER stress. Loss or gain function analysis was conducted to identify which UPR branch specifically linked to G0S2 transcription. The transcription mechanism was estimated by luciferase reporter assay and ChIP assay. RESULTS Here we showed that the activation of ER stress was accompanied by elevation of G0S2 expression in the occurrence of fatty liver disease. Furthermore, G0S2 was found to be a novel target gene of activating transcription factor 4(ATF4). We also localized one conserved ATF4-binding sequence in the 5' regulatory region of G0S2, which was responsible for transcriptional activating G0S2 by ATF4. CONCLUSION G0S2 is regulated by the PERK-eIF2α-ATF4 branch of the UPR and mediates ER stress-induced hepatic steatosis.
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Affiliation(s)
- Yunqin Ma
- Department of Endocrinology and Metabolism, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center of Diabetes, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Mingliang Zhang
- Department of Endocrinology and Metabolism, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center of Diabetes, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Haoyong Yu
- Department of Endocrinology and Metabolism, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center of Diabetes, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Junxi Lu
- Department of Endocrinology and Metabolism, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center of Diabetes, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Kenneth K Y Cheng
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Jian Zhou
- Department of Endocrinology and Metabolism, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center of Diabetes, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Haibing Chen
- Department of Endocrinology and Metabolism, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center of Diabetes, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China
| | - Weiping Jia
- Department of Endocrinology and Metabolism, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Clinical Center of Diabetes, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, 200233, China.
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Ou L, Sun T, Cheng Y, Huang L, Zhan X, Zhang P, Yang J, Zhang Y, Zhou Z. MicroRNA-214 contributes to regulation of necroptosis via targeting ATF4 in diabetes-associated periodontitis. J Cell Biochem 2019; 120:14791-14803. [PMID: 31090954 DOI: 10.1002/jcb.28740] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 02/01/2019] [Accepted: 02/14/2019] [Indexed: 12/26/2022]
Abstract
Diabetes and periodontal diseases have a mutual promoting relationship that induces severe tissue damage and cell death. The potential roles of microRNAs (miRNAs) and the type of cell death involved in diabetes-associated periodontitis are obscure. The gingival tissues of patients were obtained and MC3T3-E1 cells were costimulated with high glucose and lipopolysaccharide (LPS). Osseous morphometric analysis was evaluated with micro-CT, and histological characteristics were measured by hematoxylin/eosin and immunohistochemical staining. Cytokine secretion was confirmed by enzyme-linked immunosorbent assay, and reactive oxygen species (ROS) was measured using a DCFH-DA probe kit. Gene expression was measured by real-time quantitative reverse transcription PCR (qRT-PCR), and protein expression was assessed by Western blot and immunofluorescence analysis. The miR-214 level, receptor-interacting serine-threonine protein (RIP) 1, RIP3, and phospho-mixed lineage kinase domain-like (p-MLKL) protein expression were elevated in the inflamed gingival tissues of diabetes-associated periodontitis patients, with activating transcription factor 4 (ATF4) expression showing the opposite effect. The high glucose (22 mM) could not induce significant increase of RIP1, RIP3, and p-MLKL; however, the high glucose and LPS (500-1000 ng/mL) cotreatment resulted in increase in the number of RIP1, RIP3, and p-MLKL in MC3T3-E1 cells. NAC (ROS inhibitor) inhibited RIP1, RIP3, and increased ATF4; however, necrostatin-1 (Nec-1) (RIP1 inhibitor) specifically inhibited the protein expression of RIP1 and RIP3 and had no influence on ATF4. The use of antagomir-214 suppressed the expression of miR-214, RIP1, RIP3, and p-MLKL, but increased ATF4 protein level in glucose and LPS-induced cells. ATF4 knockdown by ATF4 small interfering RNA offset the effect of antagomir-214. RIP1- and RIP3-dependent necroptosis was confirmed in the inflamed gingival tissues of diabetes-associated periodontitis patients and high glucose- and LPS- cotreated cells. It was suggested that miR-214-targeted ATF4 participated in the regulation of necroptosis in vivo and in vitro.
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Affiliation(s)
- Lingling Ou
- Department of Stomatology, The First Affiliated Hospital of Jinan University, Guangzhou, P.R. China
| | - Ting Sun
- Department of Stomatology, The First Affiliated Hospital of Jinan University, Guangzhou, P.R. China
| | - Yaodong Cheng
- Department of Stomatology, The First Affiliated Hospital of Jinan University, Guangzhou, P.R. China
| | - Linwei Huang
- Department of Stomatology, The First Affiliated Hospital of Jinan University, Guangzhou, P.R. China
| | - Xiaozhen Zhan
- Department of Stomatology, The First Affiliated Hospital of Jinan University, Guangzhou, P.R. China
| | - Peng Zhang
- Department of Pathology, Medical School of Yichun University, Yichun, Jiangxi, P.R. China
| | - Junjie Yang
- Department of Stomatology, The First Affiliated Hospital of Jinan University, Guangzhou, P.R. China
| | - Ye Zhang
- Department of Stomatology, The First Affiliated Hospital of Jinan University, Guangzhou, P.R. China
| | - Zhiying Zhou
- Department of Stomatology, The First Affiliated Hospital of Jinan University, Guangzhou, P.R. China
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Abstract
Endoplasmic reticulum (ER) stress is a major contributor to liver disease and hepatic fibrosis, but the role it plays varies depending on the cause and progression of the disease. Furthermore, ER stress plays a distinct role in hepatocytes versus hepatic stellate cells (HSCs), which adds to the complexity of understanding ER stress and its downstream signaling through the unfolded protein response (UPR) in liver disease. Here, the authors focus on the current literature of ER stress in nonalcoholic and alcoholic fatty liver diseases, how ER stress impacts hepatocyte injury, and the role of ER stress in HSC activation and hepatic fibrosis. This review provides insight into the complex signaling and regulation of the UPR, parallels and distinctions between different liver diseases, and how ER stress may be targeted as an antisteatotic or antifibrotic therapy to limit the progression of liver disease.
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Affiliation(s)
- Jessica L. Maiers
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - Harmeet Malhi
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
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Di F, Liu J, Li S, Hong Y, Chen ZJ, Du Y. Activating transcriptional factor 4 correlated with obesity and insulin resistance in polycystic ovary syndrome. Gynecol Endocrinol 2019; 35:351-355. [PMID: 30382797 DOI: 10.1080/09513590.2018.1527307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
PCOS is a systemic disorder that is commonly characterized by insulin resistance (IR). ATF4 participates in the regulation of energy homeostasis and glucose metabolism, but its role in PCOS remains unclear. In this study, we found that ATF4 was highly expressed in human granulosa cells (hGCs) of PCOS patients with obesity and IR. Thus, we performed Spearman's correlation analysis to further investigate the correlation between ATF4 expression and obesity, lipometabolic disorders, or IR in PCOS. We found that increased ATF4 was an important trigger for lipid accumulation and abnormal insulin signal transduction in PCOS. In cultured KGN cells, insulin positively regulated the mRNA and protein abundance of ATF4. Overexpression of ATF4 significantly impaired insulin-stimulated phosphorylation of AKT. Collectively, our findings provided a novel insight into the molecular mechanisms underlying the occurrence and development of PCOS, implying that ATF4 may be a new molecular target for PCOS therapy.
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Affiliation(s)
- Fangfang Di
- a Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine , Shanghai Jiao Tong University , Shanghai , China
- b Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics , Shanghai , China
| | - Jiansheng Liu
- a Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine , Shanghai Jiao Tong University , Shanghai , China
- b Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics , Shanghai , China
| | - Shang Li
- a Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine , Shanghai Jiao Tong University , Shanghai , China
- b Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics , Shanghai , China
| | - Yan Hong
- a Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine , Shanghai Jiao Tong University , Shanghai , China
- b Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics , Shanghai , China
| | - Zi-Jiang Chen
- a Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine , Shanghai Jiao Tong University , Shanghai , China
- b Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics , Shanghai , China
- c National Research Center for Assisted Reproductive Technology and Reproductive Genetics, The Key Laboratory for Reproductive Endocrinology of Ministry of Education, Shandong Provincial Hospital , Shandong University , Jinan , China
- d Shandong Provincial Key Laboratory of Reproductive Medicine, Center for Reproductive Medicine, Shandong Provincial Hospital , Shandong University , Jinan , China
| | - Yanzhi Du
- a Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine , Shanghai Jiao Tong University , Shanghai , China
- b Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics , Shanghai , China
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Abstract
Endoplasmic reticulum (ER) stress occurs when ER homeostasis is perturbed with accumulation of unfolded/misfolded protein or calcium depletion. The unfolded protein response (UPR), comprising of inositol-requiring enzyme 1α (IRE1α), PKR-like ER kinase (PERK) and activating transcription factor 6 (ATF6) signaling pathways, is a protective cellular response activated by ER stress. However, UPR activation can also induce cell death upon persistent ER stress. The liver is susceptible to ER stress given its synthetic and other biological functions. Numerous studies from human liver samples and animal disease models have indicated a crucial role of ER stress and UPR signaling pathways in the pathogenesis of liver diseases, including non-alcoholic fatty liver disease, alcoholic liver disease, alpha-1 antitrypsin deficiency, cholestatic liver disease, drug-induced liver injury, ischemia/reperfusion injury, viral hepatitis and hepatocellular carcinoma. Extensive investigations have demonstrated the potential underlying mechanisms of the induction of ER stress and the contribution of UPR pathways during the development of the diseases. Moreover ER stress and the UPR proteins and genes have become emerging therapeutic targets to treat liver diseases.
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Affiliation(s)
- Xiaoying Liu
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Tarry Building 15-709, 303 East Superior Street, Chicago, IL 60611, Northwestern University Feinberg School of Medicine, Chicago, IL, USA, Corresponding author: Xiaoying-liu@northwestern
| | - Richard M. Green
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Tarry Building 15-709, 303 East Superior Street, Chicago, IL 60611, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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Almanza A, Carlesso A, Chintha C, Creedican S, Doultsinos D, Leuzzi B, Luís A, McCarthy N, Montibeller L, More S, Papaioannou A, Püschel F, Sassano ML, Skoko J, Agostinis P, de Belleroche J, Eriksson LA, Fulda S, Gorman AM, Healy S, Kozlov A, Muñoz‐Pinedo C, Rehm M, Chevet E, Samali A. Endoplasmic reticulum stress signalling - from basic mechanisms to clinical applications. FEBS J 2019; 286:241-278. [PMID: 30027602 PMCID: PMC7379631 DOI: 10.1111/febs.14608] [Citation(s) in RCA: 547] [Impact Index Per Article: 109.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 06/24/2018] [Accepted: 07/18/2018] [Indexed: 02/06/2023]
Abstract
The endoplasmic reticulum (ER) is a membranous intracellular organelle and the first compartment of the secretory pathway. As such, the ER contributes to the production and folding of approximately one-third of cellular proteins, and is thus inextricably linked to the maintenance of cellular homeostasis and the fine balance between health and disease. Specific ER stress signalling pathways, collectively known as the unfolded protein response (UPR), are required for maintaining ER homeostasis. The UPR is triggered when ER protein folding capacity is overwhelmed by cellular demand and the UPR initially aims to restore ER homeostasis and normal cellular functions. However, if this fails, then the UPR triggers cell death. In this review, we provide a UPR signalling-centric view of ER functions, from the ER's discovery to the latest advancements in the understanding of ER and UPR biology. Our review provides a synthesis of intracellular ER signalling revolving around proteostasis and the UPR, its impact on other organelles and cellular behaviour, its multifaceted and dynamic response to stress and its role in physiology, before finally exploring the potential exploitation of this knowledge to tackle unresolved biological questions and address unmet biomedical needs. Thus, we provide an integrated and global view of existing literature on ER signalling pathways and their use for therapeutic purposes.
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Affiliation(s)
- Aitor Almanza
- Apoptosis Research CentreNational University of IrelandGalwayIreland
| | - Antonio Carlesso
- Department of Chemistry and Molecular BiologyUniversity of GothenburgGöteborgSweden
| | - Chetan Chintha
- Apoptosis Research CentreNational University of IrelandGalwayIreland
| | | | - Dimitrios Doultsinos
- INSERM U1242University of RennesFrance
- Centre de Lutte Contre le Cancer Eugène MarquisRennesFrance
| | - Brian Leuzzi
- Apoptosis Research CentreNational University of IrelandGalwayIreland
| | - Andreia Luís
- Ludwig Boltzmann Institute for Experimental and Clinical TraumatologyAUVA Research CentreViennaAustria
| | - Nicole McCarthy
- Institute for Experimental Cancer Research in PaediatricsGoethe‐UniversityFrankfurtGermany
| | - Luigi Montibeller
- Neurogenetics GroupDivision of Brain SciencesFaculty of MedicineImperial College LondonUK
| | - Sanket More
- Department Cellular and Molecular MedicineLaboratory of Cell Death and TherapyKU LeuvenBelgium
| | - Alexandra Papaioannou
- INSERM U1242University of RennesFrance
- Centre de Lutte Contre le Cancer Eugène MarquisRennesFrance
| | - Franziska Püschel
- Cell Death Regulation GroupOncobell ProgramBellvitge Biomedical Research Institute (IDIBELL)BarcelonaSpain
| | - Maria Livia Sassano
- Department Cellular and Molecular MedicineLaboratory of Cell Death and TherapyKU LeuvenBelgium
| | - Josip Skoko
- Institute of Cell Biology and ImmunologyUniversity of StuttgartGermany
| | - Patrizia Agostinis
- Department Cellular and Molecular MedicineLaboratory of Cell Death and TherapyKU LeuvenBelgium
| | - Jackie de Belleroche
- Neurogenetics GroupDivision of Brain SciencesFaculty of MedicineImperial College LondonUK
| | - Leif A. Eriksson
- Department of Chemistry and Molecular BiologyUniversity of GothenburgGöteborgSweden
| | - Simone Fulda
- Institute for Experimental Cancer Research in PaediatricsGoethe‐UniversityFrankfurtGermany
| | | | - Sandra Healy
- Apoptosis Research CentreNational University of IrelandGalwayIreland
| | - Andrey Kozlov
- Ludwig Boltzmann Institute for Experimental and Clinical TraumatologyAUVA Research CentreViennaAustria
| | - Cristina Muñoz‐Pinedo
- Cell Death Regulation GroupOncobell ProgramBellvitge Biomedical Research Institute (IDIBELL)BarcelonaSpain
| | - Markus Rehm
- Institute of Cell Biology and ImmunologyUniversity of StuttgartGermany
| | - Eric Chevet
- INSERM U1242University of RennesFrance
- Centre de Lutte Contre le Cancer Eugène MarquisRennesFrance
| | - Afshin Samali
- Apoptosis Research CentreNational University of IrelandGalwayIreland
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Pinto BAS, França LM, Laurindo FRM, Paes AMDA. Unfolded Protein Response: Cause or Consequence of Lipid and Lipoprotein Metabolism Disturbances? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1127:67-82. [DOI: 10.1007/978-3-030-11488-6_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Xu X, Krumm C, So JS, Bare CJ, Holman C, Gromada J, Cohen DE, Lee AH. Preemptive Activation of the Integrated Stress Response Protects Mice From Diet-Induced Obesity and Insulin Resistance by Fibroblast Growth Factor 21 Induction. Hepatology 2018; 68:2167-2181. [PMID: 29698569 PMCID: PMC6203669 DOI: 10.1002/hep.30060] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 04/23/2018] [Indexed: 12/11/2022]
Abstract
Integrated stress response (ISR) is a signaling system in which phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) by stress-specific kinases and subsequent activation of activation transcription factor (ATF) 4 help restore cellular homeostasis following exposure to environmental stresses. ISR activation has been observed in metabolic diseases, including hepatic steatosis (HS), steatohepatitis (SH), and insulin resistance (IR), but it remains unclear whether ISR contributes to disease pathogenesis or represents an innate defense mechanism against metabolic stresses. Constitutive repressor of eIF2α phosphorylation (CReP) is a critical regulatory subunit of the eIF2α phosphatase complex. Here, we show that CReP ablation causes constitutive eIF2α phosphorylation in the liver, which leads to activation of the ATF4 transcriptional program including increased fibroblast growth factor 21 (FGF21) production. Liver-specific CReP knockout (CRePLKO ) mice exhibited marked browning of white adipose tissue (WAT) and increased energy expenditure and insulin sensitivity in an FGF21-dependent manner. Furthermore, CRePLKO mice were protected from high-fat diet (HFD)-induced obesity, HS, and IR. Acute CReP ablation in liver of HFD-induced obese mice also reduced adiposity and improved glucose homeostasis. Conclusion: These data suggest that CReP abundance is a critical determinant for eIF2α phosphorylation and ensuing ISR activation in the liver. Constitutive ISR activation in the liver induces FGF21 and confers protection from HFD-induced adiposity, IR, and HS in mice. Augmenting hepatic ISR may represent a therapeutic approach to treat metabolic disorders.
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Affiliation(s)
- Xu Xu
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065,Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Christopher Krumm
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065,Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Jae-Seon So
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065,Department of Medical Biotechnology, Dongguk University Gyeongju, Gyeongju-si, Korea
| | - Curtis J. Bare
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Corey Holman
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Jesper Gromada
- Regeneron Pharmaceuticals, Tarrytown, New York 10591, USA
| | - David E. Cohen
- Division of Gastroenterology and Hepatology, Joan & Sanford I. Weill Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Ann-Hwee Lee
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065,Regeneron Pharmaceuticals, Tarrytown, New York 10591, USA,Correspondence to: Ann-Hwee Lee, PhD, Regeneron Pharmaceuticals, 777 Old Saw Mill River Road, Tarrytown, NY 10591, Phone: 914-847-1997,
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Zhu X, Li H, Wu Y, Zhou J, Yang G, Wang W. lncRNA MEG3 promotes hepatic insulin resistance by serving as a competing endogenous RNA of miR-214 to regulate ATF4 expression. Int J Mol Med 2018; 43:345-357. [PMID: 30431065 PMCID: PMC6257836 DOI: 10.3892/ijmm.2018.3975] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 10/19/2018] [Indexed: 01/08/2023] Open
Abstract
MicroRNA (miR)-214 has been demonstrated to suppress gluconeogenesis by targeting activating transcription factor 4 (ATF4), which regulates gluconeogenesis by affecting the transcriptional activity of forkhead box protein O1 (FoxO1). Our previous study revealed that the upregulation of maternally expressed gene 3 (MEG3), a long noncoding RNA, enhanced hepatic insulin resistance via increased FoxO1 expression. The present study aimed to explore whether miR-214 and ATF4 were involved in the MEG3-mediated increase of FoxO1 expression. MEG3, miR-214 and ATF4 expression were examined by reverse transcription quantitative polymerase chain reaction and western blot analysis. The interaction among MEG3, miR-214 and ATF4 was analysed using the luciferase reporter assay. MEG3-targeting small interference RNAs were injected into high-fat diet (HFD)-fed mice to verify the role of MEG3 in hepatic insulin resistance in vivo. MEG-3 and ATF4 were demonstrated to be upregulated and miR-214 was indicated to be downregulated in the livers of HFD-fed and ob/ob mice. In mouse primary hepatocytes, palmitate time-dependently increased MEG3 and ATF4 but decreased miR-214 expression levels. Furthermore, MEG3 served as a competing endogenous RNA (ceRNA) for miR-214 to facilitate ATF4 expression, while miR-214 inhibition and ATF4 overexpression reversed the MEG3 knockdown-mediated decrease in the expression of FoxO1 and FoxO1-downstream targets phosphoenolpyruvate carboxykinase and glucose-6-phosphatase catalytic subunit. In HFD-fed mice, MEG3 knockdown substantially improved impaired glucose and insulin tolerance, while down-regulating HFD-induced ATF4 expression and upregulating HFD-suppressed miR-214 expression. In conclusion, MEG3 promoted hepatic insulin resistance by serving as a ceRNA of miR-214 to facilitate ATF4 expression. These data provide insight into the molecular mechanism of MEG3 involvement in the development of type 2 diabetes mellitus.
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Affiliation(s)
- Xiang Zhu
- Department of Gerontology, The First Affiliated Hospital of University of Science and Technology of China, Hefei, Anhui 230001, P.R. China
| | - Hongqi Li
- Department of Gerontology, The First Affiliated Hospital of University of Science and Technology of China, Hefei, Anhui 230001, P.R. China
| | - Yuanbo Wu
- Department of Neurology, The First Affiliated Hospital of University of Science and Technology of China, Hefei, Anhui 230001, P.R. China
| | - Jian Zhou
- Department of Gerontology, The First Affiliated Hospital of University of Science and Technology of China, Hefei, Anhui 230001, P.R. China
| | - Guangwei Yang
- Department of Endocrinology, The First Affiliated Hospital of University of Science and Technology of China, Hefei, Anhui 230001, P.R. China
| | - Weidong Wang
- Department of Gerontology, The First Affiliated Hospital of University of Science and Technology of China, Hefei, Anhui 230001, P.R. China
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Fat Mass and Obesity Associated ( FTO) Gene and Hepatic Glucose and Lipid Metabolism. Nutrients 2018; 10:nu10111600. [PMID: 30388740 PMCID: PMC6266206 DOI: 10.3390/nu10111600] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 10/20/2018] [Accepted: 10/20/2018] [Indexed: 01/17/2023] Open
Abstract
Common genetic variants of the fat mass and obesity associated (FTO) gene are strongly associated with obesity and type 2 diabetes. FTO is ubiquitously expressed. Earlier studies have focused on the role of hypothalamic FTO in the regulation of metabolism. However, recent studies suggest that expression of hepatic FTO is regulated by metabolic signals, such as nutrients and hormones, and altered FTO levels in the liver affect glucose and lipid metabolism. This review outlines recent findings on hepatic FTO in the regulation of metabolism, with particular focus on hepatic glucose and lipid metabolism. It is proposed that abnormal activity of hepatic signaling pathways involving FTO links metabolic impairments such as obesity, type 2 diabetes and nonalcoholic fatty liver disease (NAFLD). Therefore, a better understanding of these pathways may lead to therapeutic approaches to treat these metabolic diseases by targeting hepatic FTO. The overall goal of this review is to place FTO within the context of hepatic regulation of metabolism.
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Liu S, Yuan J, Yue W, Bi Y, Shen X, Gao J, Xu X, Lu Z. GCN2 deficiency protects against high fat diet induced hepatic steatosis and insulin resistance in mice. Biochim Biophys Acta Mol Basis Dis 2018; 1864:3257-3267. [PMID: 30006154 DOI: 10.1016/j.bbadis.2018.07.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 06/27/2018] [Accepted: 07/09/2018] [Indexed: 02/05/2023]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic lipid deposition and oxidative stress. It has been demonstrated that general control nonderepressible 2 (GCN2) is required to maintain hepatic fatty acid homeostasis under conditions of amino acid deprivation. However, the impact of GCN2 on the development of NAFLD has not been investigated. In this study, we used Gcn2-/- mice to investigate the effect of GCN2 on high fat diet (HFD)-induced hepatic steatosis. After HFD feeding for 12 weeks, Gcn2-/- mice were less obese than wild-type (WT) mice, and Gcn2-/- significantly attenuated HFD-induced liver dysfunction, hepatic steatosis and insulin resistance. In the livers of the HFD-fed mice, GCN2 deficiency resulted in higher levels of lipolysis genes, lower expression of genes related to FA synthesis, transport and lipogenesis, and less induction of oxidative stress. Furthermore, we found that knockdown of GCN2 attenuated, whereas overexpression of GCN2 exacerbated, palmitic acid-induced steatosis, oxidative & ER stress, and changes of peroxisome proliferator-activated receptor gamma (PPARγ), fatty acid synthase (FAS) and metallothionein (MT) expression in HepG2 cells. Collectively, our data provide evidences that GCN2 deficiency protects against HFD-induced hepatic steatosis by inhibiting lipogenesis and reducing oxidative stress. Our findings suggest that strategies to inhibit GCN2 activity in the liver may provide a novel approach to attenuate NAFLD development.
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Affiliation(s)
- Shasha Liu
- College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Juntao Yuan
- College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenhui Yue
- College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China; Department of Cardiology, Pan-Vascular Research Institute, Shanghai Tenth People's Hospital, Tongji University, Shanghai 200072, China
| | - Yanwei Bi
- Shantou University Medical College, Shantou 515041, China
| | - Xiyue Shen
- College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junling Gao
- College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Xu
- Department of Exercise Rehabilitation, Shanghai University of Sport, Shanghai 200438, China.
| | - Zhongbing Lu
- College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China.
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45
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Zhang F, Hu Z, Li G, Huo S, Ma F, Cui A, Xue Y, Han Y, Gong Q, Gao J, Bian H, Meng Z, Wu H, Long G, Tan Y, Zhang Y, Lin X, Gao X, Xu A, Li Y. Hepatic CREBZF couples insulin to lipogenesis by inhibiting insig activity and contributes to hepatic steatosis in diet-induced insulin-resistant mice. Hepatology 2018; 68:1361-1375. [PMID: 29637572 DOI: 10.1002/hep.29926] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 03/28/2018] [Accepted: 04/04/2018] [Indexed: 01/05/2023]
Abstract
UNLABELLED Insulin is critical for the regulation of de novo fatty acid synthesis, which converts glucose to lipid in the liver. However, how insulin signals are transduced into the cell and then regulate lipogenesis remains to be fully understood. Here, we identified CREB/ATF bZIP transcription factor (CREBZF) of the activating transcription factor/cAMP response element-binding protein (ATF/CREB) gene family as a key regulator for lipogenesis through insulin-Akt signaling. Insulin-induced gene 2a (Insig-2a) decreases during refeeding, allowing sterol regulatory element binding protein 1c to be processed to promote lipogenesis; but the mechanism of reduction is unknown. We show that Insig-2a inhibition is mediated by insulin-induced CREBZF. CREBZF directly inhibits transcription of Insig-2a through association with activating transcription factor 4. Liver-specific knockout of CREBZF causes an induction of Insig-2a and Insig-1 and resulted in repressed lipogenic program in the liver of mice during refeeding or upon treatment with streptozotocin and insulin. Moreover, hepatic CREBZF deficiency attenuates hepatic steatosis in high-fat, high-sucrose diet-fed mice. Importantly, expression levels of CREBZF are increased in livers of diet-induced insulin resistance or genetically obese ob/ob mice and humans with hepatic steatosis, which may underscore the potential role of CREBZF in the development of sustained lipogenesis in the liver under selective insulin resistance conditions. CONCLUSION These findings uncover an unexpected mechanism that couples changes in extracellular hormonal signals to hepatic lipid homeostasis; disrupting CREBZF function may have the therapeutic potential for treating fatty liver disease and insulin resistance. (Hepatology 2018).
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Affiliation(s)
- Feifei Zhang
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhimin Hu
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Gaopeng Li
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong, China
| | - Shaofeng Huo
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Fengguang Ma
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Aoyuan Cui
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yaqian Xue
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yamei Han
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Qi Gong
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Jing Gao
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hua Bian
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China.,Fudan Institute for Metabolic Diseases, Shanghai, China
| | - Zhuoxian Meng
- Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Haifu Wu
- Metabolic and Bariatric Surgery of Department of General Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Gang Long
- Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Yi Tan
- Pediatric Research Institute at the Department of Pediatrics, Wendy L. Novak Diabetes Care Center, University of Louisville, Louisville, KY
| | - Yan Zhang
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong, China
| | - Xu Lin
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xin Gao
- Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China.,Fudan Institute for Metabolic Diseases, Shanghai, China
| | - Aimin Xu
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Hong Kong, China.,Department of Medicine, The University of Hong Kong, Hong Kong, China.,Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China
| | - Yu Li
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
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46
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Gasparin FRS, Carreño FO, Mewes JM, Gilglioni EH, Pagadigorria CLS, Natali MRM, Utsunomiya KS, Constantin RP, Ouchida AT, Curti C, Gaemers IC, Elferink RPJO, Constantin J, Ishii-Iwamoto EL. Sex differences in the development of hepatic steatosis in cafeteria diet-induced obesity in young mice. Biochim Biophys Acta Mol Basis Dis 2018; 1864:2495-2509. [DOI: 10.1016/j.bbadis.2018.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 03/29/2018] [Accepted: 04/06/2018] [Indexed: 02/08/2023]
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47
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Zhao X, Zhou H, Cheng Y, Yu W, Luo G, Duan C, Yao F, Xiao B, Feng C, Xia X, Wei M, Wang Y, Li J, Dai R. Reduction in activating transcription factor 4 promotes carbon tetrachloride and lipopolysaccharide/D‑galactosamine‑mediated liver injury in mice. Mol Med Rep 2018; 18:1718-1725. [PMID: 29845243 DOI: 10.3892/mmr.2018.9080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 05/18/2018] [Indexed: 11/06/2022] Open
Abstract
Although activating transcription factor 4 (ATF4) is involved in the regulation of numerous biological functions, whether ATF4 has a direct role in liver injury is unknown. The aim of the present study was to investigate the role of ATF4 in liver injury using mouse models. The results revealed that ATF4 protein is expressed markedly higher in the mouse liver when in comparison with other tissues. Notably, tunicamycin treatment, an endoplasmic reticulum (ER) stress inducer, induced the phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), but decreased ATF4 protein levels in the mouse liver. This suggested an unconventional regulation pattern of ATF4 protein not associated with ER stress or eIF2α. In addition, it was also observed that the liver levels of ATF4 protein were significantly reduced upon chronic liver injury induced by carbon tetrachloride (CCl4). ATF4 protein was also decreased in acute liver injury induced by lipopolysaccharide (LPS) plus D‑galactosamine (D‑GalN). Furthermore, the results revealed that knockdown of ATF4 by injecting ATF4‑targeting Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)‑CRISPR associated protein 9 plasmids exacerbated CCl4 and LPS/D‑GalN‑induced liver injury as demonstrated by elevated serum aspartate transaminase and alanine aminotransferase levels. ATF4 suppression also enhanced CCl4 and LPS/D‑GalN mediated c‑Jun N‑terminal kinase activation. By contrast, ATF4 overexpression alleviated CCl4 and LPS/D‑GalN‑induced liver injury. Taken together, these observations suggested that ATF4 may serve a protective role in the mouse liver.
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Affiliation(s)
- Xiaofang Zhao
- Department of Biochemistry and Molecular Biology, Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Hong Zhou
- Department of Biochemistry and Molecular Biology, Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Ying Cheng
- Department of Biochemistry and Molecular Biology, Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Wenjing Yu
- Department of Biochemistry and Molecular Biology, Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Guosong Luo
- Department of Hepatobiliary Surgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Chunyan Duan
- Department of Biochemistry and Molecular Biology, Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Fuli Yao
- Department of Biochemistry and Molecular Biology, Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Bin Xiao
- Department of Biochemistry and Molecular Biology, Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Chunhong Feng
- Department of Hepatobiliary Surgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Xianming Xia
- Department of Hepatobiliary Surgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Mei Wei
- Department of Liver Diseases, The Affiliated Hospital of Chinese Traditional Medicine, Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Yong Wang
- Liver Diseases Laboratory, Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Jing Li
- Department of Hepatobiliary Surgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
| | - Rongyang Dai
- Liver Diseases Laboratory, Southwest Medical University, Luzhou, Sichuan 646000, P.R. China
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48
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Örd T, Örd D, Örd T. TRIB3 limits FGF21 induction during in vitro and in vivo nutrient deficiencies by inhibiting C/EBP-ATF response elements in the Fgf21 promoter. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1861:271-281. [PMID: 29378327 DOI: 10.1016/j.bbagrm.2018.01.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 01/21/2018] [Accepted: 01/22/2018] [Indexed: 12/11/2022]
Abstract
Mammals must be able to endure periods of limited food availability, and the liver plays a central role in the adaptation to nutritional stresses. TRIB3 (Tribbles homolog 3) is a cellular stress-inducible gene with a liver-centric expression pattern and it has been implicated in stress response regulation and metabolic control. In the current article, we study the involvement of TRIB3 in responses to nutrient deficiencies, including fasting for up to 48 h in mice. We show that hepatic expression of Trib3 is increased after 48 h of fasting and mice with a targeted deletion of the Trib3 gene present elevated hepatic triglyceride content and liver weight at 48 h, along with an upregulation of lipid utilization genes in the liver. Further, hepatic and serum levels of the metabolic stress hormone FGF21 are considerably increased in 48-h-fasted Trib3 knockout mice compared to wild type. Trib3 deficiency also leads to elevated FGF21 levels in the mouse liver during essential amino acid deficiency and in cultured mouse embryonic fibroblasts during glucose starvation. Reporter assays reveal that TRIB3 regulates FGF21 by inhibiting ATF4-mediated, C/EBP-ATF site-dependent activation of Fgf21 transcription. Based on chromatin immunoprecipitation from mouse liver, the binding of TRIB3 and ATF4, a transcription factor known to physically interact with TRIB3, is significantly increased at the Fgf21 promoter following 48 h of fasting. Thus, under nutrient-limiting conditions that stimulate ATF4 activity, TRIB3 is implicated in the regulation of metabolic adaptation by restraining the transcription of Fgf21.
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Affiliation(s)
- Tiit Örd
- Estonian Biocentre, Institute of Genomics, University of Tartu, Riia 23b, 51010 Tartu, Estonia
| | - Daima Örd
- Estonian Biocentre, Institute of Genomics, University of Tartu, Riia 23b, 51010 Tartu, Estonia
| | - Tõnis Örd
- Estonian Biocentre, Institute of Genomics, University of Tartu, Riia 23b, 51010 Tartu, Estonia.
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49
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Yeh KY, Lai CY, Lin CY, Hsu CC, Lo CP, Her GM. ATF4 overexpression induces early onset of hyperlipidaemia and hepatic steatosis and enhances adipogenesis in zebrafish. Sci Rep 2017; 7:16362. [PMID: 29180630 PMCID: PMC5703967 DOI: 10.1038/s41598-017-16587-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 11/13/2017] [Indexed: 02/08/2023] Open
Abstract
Activating transcription factor 4 (ATF4) is constitutively expressed in a variety of tissues, and regulates several pathological features associated with metabolic diseases such as non-alcoholic fatty liver diseases (NAFLD) and obesity. However, the role of ATF4 in animal model systems is poorly understood. To investigate ATF4 functions in zebrafish, we conditionally expressed ATF4 proteins, using a Tet-off transgenic system. We observed early-onset hyperlipidaemia and liver steatosis in ATF4 transgenic zebrafish (ATs) without doxycycline treatment (ATs − Dox). Oil Red O (ORO)-stained signals were predominant in the intravascular blood vessels and liver buds of larval ATs − Dox, indicating that ATF4 functionally promotes lipogenesis. Further, ATF4 overexpression accompanied the stimulation of the unfolded protein response. Therefore, adult ATs − Dox showed increased lipid accumulation, which led, in turn, to liver steatosis. Liver histology and ORO staining of ATs − Dox hepatocytes also indicated oxidative stress and induced NASH-like phenotypes. Moreover, ATF4 overexpression accelerated adipocyte differentiation via CCAAT enhancer binding protein-beta and peroxisome proliferator activated receptor-gamma inducible expression. ATs-Dox zebrafish showed increased weight gain with larger fat pads due to adipocyte hyperplasia. In this study, we report that ATF4 is a potential stimulator of lipid biosynthesis and adipogenesis in zebrafish.
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Affiliation(s)
- Kun-Yun Yeh
- Division of Hemato-Oncology, Department of Internal Medicine, Chang-Chung Memorial Hospital, 222 Maijin Road, Keelung, 204, Taiwan
| | - Chi-Yu Lai
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, 2, Pei Ning Road, Keelung, 202, Taiwan
| | - Chiu-Ya Lin
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, 2, Pei Ning Road, Keelung, 202, Taiwan
| | - Chia-Chun Hsu
- Department of Radiology, Buddhist Tzu Chi General Hospital, Taichung Branch, No. 66 Fēngxìng Road Section 1, Taichung, 427, Taiwan.,School of Medicine, Tzu Chi University, No.701, Sec. 3, Jhongyang Road, Hualien, 97004, Taiwan
| | - Chung-Ping Lo
- Department of Radiology, Buddhist Tzu Chi General Hospital, Taichung Branch, No. 66 Fēngxìng Road Section 1, Taichung, 427, Taiwan.,School of Medicine, Tzu Chi University, No.701, Sec. 3, Jhongyang Road, Hualien, 97004, Taiwan
| | - Guor Mour Her
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, 2, Pei Ning Road, Keelung, 202, Taiwan.
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50
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Endoplasmic Reticulum Stress in Hearing Loss. JOURNAL OF OTORHINOLARYNGOLOGY, HEARING AND BALANCE MEDICINE 2017. [DOI: 10.3390/ohbm1010003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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