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Oh SJ, Hwang Y, Hur KY, Lee MS. Lysosomal Ca 2+ as a mediator of palmitate-induced lipotoxicity. Cell Death Discov 2023; 9:100. [PMID: 36944629 PMCID: PMC10030853 DOI: 10.1038/s41420-023-01379-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 02/22/2023] [Accepted: 02/23/2023] [Indexed: 03/23/2023] Open
Abstract
While the mechanism of lipotoxicity by palmitic acid (PA), an effector of metabolic stress in vitro and in vivo, has been extensively investigated, molecular details of lipotoxicity are still not fully characterized. Since recent studies reported that PA can exert lysosomal stress in addition to well-known ER and mitochondrial stress, we studied the role of lysosomal events in lipotoxicity by PA, focusing on lysosomal Ca2+. We found that PA induced accumulation of mitochondrial ROS and that mitochondrial ROS induced release of lysosomal Ca2+ due to lysosomal Ca2+ exit channel activation. Lysosomal Ca2+ release led to increased cytosolic Ca2+ which induced mitochondrial permeability transition (mPT). Chelation of cytoplasmic Ca2+ or blockade of mPT with olesoxime or decylubiquinone (DUB) suppressed lipotoxicity. Lysosomal Ca2+ release led to reduced lysosomal Ca2+ content which was replenished by ER Ca2+, the largest intracellular Ca2+ reservoir (ER → lysosome Ca2+ refilling), which in turn activated store-operated Ca2+ entry (SOCE). Inhibition of ER → lysosome Ca2+ refilling by blockade of ER Ca2+ exit channel using dantrolene or inhibition of SOCE using BTP2 inhibited lipotoxicity in vitro. Dantrolene or DUB also inhibited lipotoxic death of hepatocytes in vivo induced by administration of ethyl palmitate together with LPS. These results suggest a novel pathway of lipotoxicity characterized by mPT due to lysosomal Ca2+ release which was supplemented by ER → lysosome Ca2+ refilling and subsequent SOCE, and also suggest the potential role of modulation of ER → lysosome Ca2+ refilling by dantrolene or other blockers of ER Ca2+ exit channels in disease conditions characterized by lipotoxicity such as metabolic syndrome, diabetes, cardiomyopathy or nonalcoholic steatohepatitis.
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Affiliation(s)
- Soo-Jin Oh
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, 06355, Korea
- Department of Integrated Biomedical Science, Soonchunhyang Institute of Medi-bio Science and Division of Endocrinology, Department of Internal Medicine, Soonchunhyang Medical Center, Soonchunhyang University College of Medicine, Cheonan, Korea
| | - Yeseong Hwang
- Severance Biomedical Science Institute, Graduate school of Medical Science, BK21 Project, Yonsei University College of Medicine, Seoul, 03722, Korea
| | - Kyu Yeon Hur
- Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Myung-Shik Lee
- Department of Integrated Biomedical Science, Soonchunhyang Institute of Medi-bio Science and Division of Endocrinology, Department of Internal Medicine, Soonchunhyang Medical Center, Soonchunhyang University College of Medicine, Cheonan, Korea.
- Severance Biomedical Science Institute, Graduate school of Medical Science, BK21 Project, Yonsei University College of Medicine, Seoul, 03722, Korea.
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2
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DGKB mediates radioresistance by regulating DGAT1-dependent lipotoxicity in glioblastoma. Cell Rep Med 2023; 4:100880. [PMID: 36603576 PMCID: PMC9873821 DOI: 10.1016/j.xcrm.2022.100880] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Revised: 08/08/2022] [Accepted: 12/08/2022] [Indexed: 01/06/2023]
Abstract
Glioblastoma (GBM) currently has a dismal prognosis. GBM cells that survive radiotherapy contribute to tumor progression and recurrence with metabolic advantages. Here, we show that diacylglycerol kinase B (DGKB), a regulator of the intracellular concentration of diacylglycerol (DAG), is significantly downregulated in radioresistant GBM cells. The downregulation of DGKB increases DAG accumulation and decreases fatty acid oxidation, contributing to radioresistance by reducing mitochondrial lipotoxicity. Diacylglycerol acyltransferase 1 (DGAT1), which catalyzes the formation of triglycerides from DAG, is increased after ionizing radiation. Genetic inhibition of DGAT1 using short hairpin RNA (shRNA) or microRNA-3918 (miR-3918) mimic suppresses radioresistance. We discover that cladribine, a clinical drug, activates DGKB, inhibits DGAT1, and sensitizes GBM cells to radiotherapy in vitro and in vivo. Together, our study demonstrates that DGKB downregulation and DGAT1 upregulation confer radioresistance by reducing mitochondrial lipotoxicity and suggests DGKB and DGAT1 as therapeutic targets to overcome GBM radioresistance.
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3
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Modelling fatty liver disease with mouse liver-derived multicellular spheroids. Biomaterials 2022; 290:121817. [DOI: 10.1016/j.biomaterials.2022.121817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/28/2022] [Accepted: 09/19/2022] [Indexed: 11/19/2022]
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4
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Pelargonidin-3-O-Glucoside Encapsulated Pectin-Chitosan-Nanoliposomes Recovers Palmitic Acid-Induced Hepatocytes Injury. Antioxidants (Basel) 2022; 11:antiox11040623. [PMID: 35453309 PMCID: PMC9025254 DOI: 10.3390/antiox11040623] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/18/2022] [Accepted: 03/22/2022] [Indexed: 02/04/2023] Open
Abstract
Pelargonidin-3-O-glucoside (Pg) is a well-known anthocyanin derivative possessing potential biological activity. Nonetheless, the bioactivity of Pg is limited due to instability in the physiological environment. Functionalized nanoliposomes using chitosan and/or pectin coating is an excellent carrier system for nanoencapsulation of food bioactive compounds such as Pg. Therefore, this study aimed to investigate the protective effect of Pg-loaded pectin–chitosan coated nanoliposomes against palmitic acid (PA)-induced hepatocytes injury in L02 cells. Firstly, Pg-loaded pectin–chitosan coated nanoliposomes were characterized using the DLS, HPLC, TEM, and cellular uptake study in L02 cells. Thereafter, we assayed the protective effect against PA-induced lipotoxicity, ROS and O2•− generation, mitochondrial dysfunction (MMP), and GSH depletion. Results showed that Pg-loaded nanoliposomes significantly reduced the PA-induced L02 cells toxicity via suppressing ROS production, O2•− generation, MMP collapse, and GSH reduction, whereas the free-Pg samples were not effective. On the contrary, the chitosan and/or pectin coated nanoliposomes showed higher results compared to coating-free nanoliposomes. Altogether, the results of our study ensured that Pg-loaded pectin–chitosan coated nanoliposomes was capable of reducing PA-induced hepatocytes injury. Thus, pectin–chitosan coated nanoliposomes can be useful for hepatocellular delivery of hydrophilic compounds with greater biological activity.
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5
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Castelli S, De Falco P, Ciccarone F, Desideri E, Ciriolo MR. Lipid Catabolism and ROS in Cancer: A Bidirectional Liaison. Cancers (Basel) 2021; 13:cancers13215484. [PMID: 34771647 PMCID: PMC8583096 DOI: 10.3390/cancers13215484] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/28/2021] [Accepted: 10/28/2021] [Indexed: 12/14/2022] Open
Abstract
Although cancer cell metabolism was mainly considered to rely on glycolysis, with the concomitant impairment of mitochondrial metabolism, it has recently been demonstrated that several tumor types are sustained by oxidative phosphorylation (OXPHOS). In this context, endogenous fatty acids (FAs) deriving from lipolysis or lipophagy are oxidised into the mitochondrion, and are used as a source of energy through OXPHOS. Because the electron transport chain is the main source of ROS, cancer cells relying on fatty acid oxidation (FAO) need to be equipped with antioxidant systems that maintain the ROS levels under the death threshold. In those conditions, ROS can act as second messengers, favouring proliferation and survival. Herein, we highlight the different responses that tumor cells adopt when lipid catabolism is augmented, taking into account the different ROS fates. Many papers have demonstrated that the pro- or anti-tumoral roles of endogenous FA usage are hugely dependent on the tumor type, and on the capacity of cancer cells to maintain redox homeostasis. In light of this, clinical studies have taken advantage of the boosting of lipid catabolism to increase the efficacy of tumor therapy, whereas, in other contexts, antioxidant compounds are useful to reduce the pro-survival effects of ROS deriving from FAO.
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Affiliation(s)
- Serena Castelli
- Department of Biology, University of Rome “Tor Vergata”, Via Della Ricerca Scientifica 1, 00133 Rome, Italy; (S.C.); (P.D.F.); (E.D.)
| | - Pamela De Falco
- Department of Biology, University of Rome “Tor Vergata”, Via Della Ricerca Scientifica 1, 00133 Rome, Italy; (S.C.); (P.D.F.); (E.D.)
| | - Fabio Ciccarone
- IRCCS San Raffaele Pisana, Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, 00166 Rome, Italy;
| | - Enrico Desideri
- Department of Biology, University of Rome “Tor Vergata”, Via Della Ricerca Scientifica 1, 00133 Rome, Italy; (S.C.); (P.D.F.); (E.D.)
| | - Maria Rosa Ciriolo
- Department of Biology, University of Rome “Tor Vergata”, Via Della Ricerca Scientifica 1, 00133 Rome, Italy; (S.C.); (P.D.F.); (E.D.)
- IRCCS San Raffaele Pisana, Via Della Pisana 235, 00163 Rome, Italy
- Correspondence:
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6
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Broadfield LA, Duarte JAG, Schmieder R, Broekaert D, Veys K, Planque M, Vriens K, Karasawa Y, Napolitano F, Fujita S, Fujii M, Eto M, Holvoet B, Vangoitsenhoven R, Fernandez-Garcia J, Van Elsen J, Dehairs J, Zeng J, Dooley J, Rubio RA, van Pelt J, Grünewald TGP, Liston A, Mathieu C, Deroose CM, Swinnen JV, Lambrechts D, di Bernardo D, Kuroda S, De Bock K, Fendt SM. Fat Induces Glucose Metabolism in Nontransformed Liver Cells and Promotes Liver Tumorigenesis. Cancer Res 2021; 81:1988-2001. [PMID: 33687947 DOI: 10.1158/0008-5472.can-20-1954] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 01/27/2021] [Accepted: 03/02/2021] [Indexed: 12/21/2022]
Abstract
Hepatic fat accumulation is associated with diabetes and hepatocellular carcinoma (HCC). Here, we characterize the metabolic response that high-fat availability elicits in livers before disease development. After a short term on a high-fat diet (HFD), otherwise healthy mice showed elevated hepatic glucose uptake and increased glucose contribution to serine and pyruvate carboxylase activity compared with control diet (CD) mice. This glucose phenotype occurred independently from transcriptional or proteomic programming, which identifies increased peroxisomal and lipid metabolism pathways. HFD-fed mice exhibited increased lactate production when challenged with glucose. Consistently, administration of an oral glucose bolus to healthy individuals revealed a correlation between waist circumference and lactate secretion in a human cohort. In vitro, palmitate exposure stimulated production of reactive oxygen species and subsequent glucose uptake and lactate secretion in hepatocytes and liver cancer cells. Furthermore, HFD enhanced the formation of HCC compared with CD in mice exposed to a hepatic carcinogen. Regardless of the dietary background, all murine tumors showed similar alterations in glucose metabolism to those identified in fat exposed nontransformed mouse livers, however, particular lipid species were elevated in HFD tumor and nontumor-bearing HFD liver tissue. These findings suggest that fat can induce glucose-mediated metabolic changes in nontransformed liver cells similar to those found in HCC. SIGNIFICANCE: With obesity-induced hepatocellular carcinoma on a rising trend, this study shows in normal, nontransformed livers that fat induces glucose metabolism similar to an oncogenic transformation.
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Affiliation(s)
- Lindsay A Broadfield
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium.,Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
| | - João André Gonçalves Duarte
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium.,Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
| | - Roberta Schmieder
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium.,Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
| | - Dorien Broekaert
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium.,Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
| | - Koen Veys
- Department of Oncology (KU Leuven) and Center for Cancer Biology (VIB), Laboratory of Angiogenesis and Vascular Metabolism, Leuven, Belgium
| | - Mélanie Planque
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium.,Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
| | - Kim Vriens
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium.,Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
| | - Yasuaki Karasawa
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, Japan.,Department of Neurosurgery, University of Tokyo Hospital, Tokyo, Japan.,Department of Rehabilitation, University of Tokyo Hospital, Tokyo, Japan
| | - Francesco Napolitano
- Telethon Institute of Genetics and Medicine (TIGEM), System Biology and Bioinformatics Laboratory and High Content Screening Facility, Naples, Italy
| | - Suguru Fujita
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, Japan
| | - Masashi Fujii
- Department of Mathematical and Life Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan
| | - Miki Eto
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, Japan
| | - Bryan Holvoet
- Department of Imaging and Pathology, Nuclear Medicine and Molecular Imaging, KU Leuven, Belgium
| | | | - Juan Fernandez-Garcia
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium.,Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
| | - Joke Van Elsen
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium.,Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
| | - Jonas Dehairs
- Department of Oncology, Laboratory of Lipid Metabolism and Cancer, KU Leuven Cancer Institute, Leuven, Belgium
| | - Jia Zeng
- School of Life Science, Hunan University of Science and Technology, Xiangtan, Hunan, China
| | - James Dooley
- Department of Microbiology and Immunology, KU Leuven; and Translational Immunology Laboratory, Leuven, Belgium
| | - Rebeca Alba Rubio
- Max-Eder Research Group for Pediatric Sarcoma Biology, Institute of Pathology, Faculty of Medicine, Munich, Germany
| | - Jos van Pelt
- Department of Oncology, Laboratory of Clinical Digestive Oncology, KU, Leuven, Belgium
| | - Thomas G P Grünewald
- Max-Eder Research Group for Pediatric Sarcoma Biology, Institute of Pathology, Faculty of Medicine, Munich, Germany.,Hopp Children's Cancer Center (KiTZ), Heidelberg, Germany.,Division of Translational Pediatric Sarcoma Research, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), Heidelberg, Germany.,Institute of Pathology, Heidelberg University Hospital, Heidelberg, Germany
| | - Adrian Liston
- Department of Microbiology and Immunology, KU Leuven; and Translational Immunology Laboratory, Leuven, Belgium
| | - Chantal Mathieu
- Department of Endocrinology, UZ Gasthuisberg KU Leuven, Leuven, Belgium
| | - Christophe M Deroose
- Department of Imaging and Pathology, Nuclear Medicine and Molecular Imaging, KU Leuven, Belgium
| | - Johannes V Swinnen
- Department of Oncology, Laboratory of Lipid Metabolism and Cancer, KU Leuven Cancer Institute, Leuven, Belgium
| | - Diether Lambrechts
- Department of Human Genetics, Laboratory of Translational Genetics, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium
| | - Diego di Bernardo
- Telethon Institute of Genetics and Medicine (TIGEM), System Biology and Bioinformatics Laboratory and High Content Screening Facility, Naples, Italy.,Department of Chemical, Materials and Industrial Production Engineering, University of Naples Federico II, Naples, Italy
| | - Shinya Kuroda
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, Japan
| | - Katrien De Bock
- Department of Health Sciences and Technology, Laboratory of Exercise and Health, ETH Zurich, Zurich, Switzerland
| | - Sarah-Maria Fendt
- Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, Leuven, Belgium. .,Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
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7
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Li Y, Ding H, Liu L, Song Y, Du X, Feng S, Wang X, Li X, Wang Z, Li X, Li J, Wu J, Liu G. Non-esterified Fatty Acid Induce Dairy Cow Hepatocytes Apoptosis via the Mitochondria-Mediated ROS-JNK/ERK Signaling Pathway. Front Cell Dev Biol 2020; 8:245. [PMID: 32411699 PMCID: PMC7198733 DOI: 10.3389/fcell.2020.00245] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 03/24/2020] [Indexed: 12/30/2022] Open
Abstract
Elevated plasma non-esterified fatty acid (NEFA) levels and hepatocytes damage are characteristics of ketosis in dairy cows. Oxidative stress is associated with the pathogenesis of NEFA-induced liver damage. However, the exact mechanism by which oxidative stress mediates NEFA-induced hepatocytes apoptosis and liver injury remains poorly understood. The results of the present study demonstrated that NEFA contribute to reactive oxygen species (ROS) generation, resulting in an imbalance between oxidative and antioxidant species, transcriptional activation of p53, transcriptional inhibition of nuclear factor E2-related factor 2 (Nrf2), loss of mitochondria membrane potential (MMP) and release of apoptosis-inducing factor (AIF) and cytochrome c (cyt c) into the cytosol, leading to hepatocytes apoptosis. Besides, NEFA triggered apoptosis in dairy cow hepatocytes via the regulation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated protein kinases 1 and 2 (ERK1/2), Bcl-2-associated X protein (Bax), B-cell lymphoma gene 2 (Bcl-2), caspase 9 and poly (ADP-ribose) polymerase (PARP). Pretreatment with the inhibitor SP600125 or PD98059 or the antioxidant N-acetylcysteine (NAC) revealed that NEFA-ROS-JNK/ERK-mediated mitochondrial signaling pathway plays a crucial role in NEFA-induced hepatocytes apoptosis. Moreover, the results suggested that the transcription factors p53 and Nrf2 function downstream of this NEFA-ROS-JNK/ERK pathway and are involved in NEFA-induced hepatocytes apoptosis. In conclusion, these findings indicate that the NEFA-ROS-JNK/ERK-mediated mitochondrial pathway plays an important role in NEFA-induced dairy cow hepatocytes apoptosis and strongly suggests that the inhibitors SP600125 and PD98059 and the antioxidant NAC may be developed as therapeutics to prevent hyperlipidemia-induced apoptotic damage in ketotic dairy cows.
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Affiliation(s)
- Yu Li
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, China.,Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Hongyan Ding
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Leihong Liu
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Yuxiang Song
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xiliang Du
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Shibin Feng
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Xichun Wang
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Xiaobing Li
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Zhe Wang
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xinwei Li
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Jinchun Li
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Jinjie Wu
- College of Animal Science and Technology, Anhui Agricultural University, Hefei, China
| | - Guowen Liu
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
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8
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Zhao Y, Li H, Chai Z, Shi W, Li X, Ma H. An endoplasmic reticulum-targeting fluorescent probe for imaging ˙OH in living cells. Chem Commun (Camb) 2020; 56:6344-6347. [DOI: 10.1039/d0cc00233j] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A new ER-targeting fluorescent probe for ˙OH is developed and applied to imaging ˙OH generation as well as lipid droplet formation in ER stress.
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Affiliation(s)
- Yanyan Zhao
- Beijing National Laboratory for Molecular Sciences
- Key Laboratory of Analytical Chemistry for Living Biosystems
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
| | - Hongyu Li
- Beijing National Laboratory for Molecular Sciences
- Key Laboratory of Analytical Chemistry for Living Biosystems
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
| | - Ziyin Chai
- Beijing National Laboratory for Molecular Sciences
- Key Laboratory of Analytical Chemistry for Living Biosystems
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
| | - Wen Shi
- Beijing National Laboratory for Molecular Sciences
- Key Laboratory of Analytical Chemistry for Living Biosystems
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
| | - Xiaohua Li
- Beijing National Laboratory for Molecular Sciences
- Key Laboratory of Analytical Chemistry for Living Biosystems
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
| | - Huimin Ma
- Beijing National Laboratory for Molecular Sciences
- Key Laboratory of Analytical Chemistry for Living Biosystems
- Institute of Chemistry
- Chinese Academy of Sciences
- Beijing 100190
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9
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Polysaccharide from Rubus chingii Hu affords protection against palmitic acid-induced lipotoxicity in human hepatocytes. Int J Biol Macromol 2019; 133:1063-1071. [DOI: 10.1016/j.ijbiomac.2019.04.176] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/25/2019] [Accepted: 04/25/2019] [Indexed: 01/06/2023]
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10
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Pandey V, Hatzimanikatis V. Investigating the deregulation of metabolic tasks via Minimum Network Enrichment Analysis (MiNEA) as applied to nonalcoholic fatty liver disease using mouse and human omics data. PLoS Comput Biol 2019; 15:e1006760. [PMID: 31002661 PMCID: PMC6493771 DOI: 10.1371/journal.pcbi.1006760] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 05/01/2019] [Accepted: 01/06/2019] [Indexed: 01/07/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is associated with metabolic syndromes spanning a wide spectrum of diseases, from simple steatosis to the more complex nonalcoholic steatohepatitis. To identify the deregulation that occurs in metabolic processes at the molecular level that give rise to these various NAFLD phenotypes, algorithms such as pathway enrichment analysis (PEA) can be used. These analyses require the use of predefined pathway maps, which are composed of reactions describing metabolic processes/subsystems. Unfortunately, the annotation of the metabolic subsystems can differ depending on the pathway database used, making these approaches subject to biases associated with different pathway annotations, and these methods cannot capture the balancing of cofactors and byproducts through the complex nature and interactions of genome-scale metabolic networks (GEMs). Here, we introduce a framework entitled Minimum Network Enrichment Analysis (MiNEA) that is applied to GEMs to generate all possible alternative minimal networks (MiNs), which are possible and feasible networks composed of all the reactions pertaining to various metabolic subsystems that can synthesize a target metabolite. We applied MiNEA to investigate deregulated MiNs and to identify key regulators in different NAFLD phenotypes, such as a fatty liver and liver inflammation, in both humans and mice by integrating condition-specific transcriptomics data from liver samples. We identified key deregulations in the synthesis of cholesteryl esters, cholesterol, and hexadecanoate in both humans and mice, and we found that key regulators of the hydrogen peroxide synthesis network were regulated differently in humans and mice. We further identified which MiNs demonstrate the general and specific characteristics of the different NAFLD phenotypes. MiNEA is applicable to any GEM and to any desired target metabolite, making MiNEA flexible enough to study condition-specific metabolism for any given disease or organism. This work aims to introduce a network-based enrichment analysis using metabolic networks and transcriptomics data. Previous pathways/subsystems enrichment methods use predefined gene annotations of metabolic processes and gene annotations can differ based on different resources and can produce bias in pathway definitions. Thus, we introduce a framework, Minimum Network Enrichment Analysis (MiNEA), which first finds all possible minimal-size networks for a given metabolic process/task and then identifies deregulated minimal networks using deregulated genes between two conditions. MiNEA also identifies the deregulation in key reactions that are overlapped across all possible minimal-size networks. We applied MiNEA to identify deregulated metabolic tasks and their synthesis networks in the steatosis and the nonalcoholic steatohepatitis (NASH) diseases using a metabolic network and transcriptomics data of mouse and human liver samples. We identified key regulators of NASH for the synthesis networks of hydrogen peroxide and ceramide in both humans and mice. We also identified opposite deregulation in NASH for the phosphatidylserine synthesis network between humans and mice. MiNEA finds synthesis networks for a given target metabolite and due to this it is flexible to study deregulation in different phenotypes. MiNEA can be widely applicable for studying context-specific metabolism for any organism because the metabolic networks and context-specific gene expression data are now available for many organisms.
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Affiliation(s)
- Vikash Pandey
- Laboratory of Computational Systems Biotechnology, EPFL, Lausanne, Switzerland
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11
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Chien Y, Huang CS, Lin HC, Lu KH, Tsai PH, Lai YH, Chen KH, Lee SD, Huang YH, Wang CY. Improvement of non-alcoholic steatohepatitis by hepatocyte-like cells generated from iPSCs with Oct4/Sox2/Klf4/Parp1. Oncotarget 2018; 9:18594-18606. [PMID: 29719629 PMCID: PMC5915096 DOI: 10.18632/oncotarget.23603] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 11/17/2017] [Indexed: 12/21/2022] Open
Abstract
The prevalence of nonalcoholic fatty liver disease (NAFLD) is usually increased with age. Non-alcoholic steatohepatitis (NASH), a serious form of NAFLD, may lead to cirrhosis and end-stage liver diseases. Induced pluripotent stem cells (iPSCs) hold promising potential in personalized medicine. Although obviation of c-Myc reduces tumorigenic risk, it also largely reduced the generation of iPSCs. Recently, Poly(ADP-ribose) polymerase 1 (Parp1) has been reported to enhance cell reprogramming. In this study, we demonstrated that forced expression of Oct4/Sox2/Klf4/Parp1 (OSKP) effectively promoted iPSC generation from senescent somatic cells from 18-month-old mouse. The iPSCs presented regular pluripotent properties, ability to form smaller teratoma with smaller size, and the potential for tridermal differentiation including hepatocyte-like cells (OSKP-iPSC-Heps). Resembled to fetal hepatocytes but not senescent hepatocytes, these OSKP-iPSC-Heps possessed antioxidant ability and were resistant to oxidative insult induced by H2O2 or exogenous fatty acid. Intrasplenic transplantation of OSKP-iPSC-Heps ameliorated the triglyceride over-accumulation and hepatitis, prevented the production of inflammatory cytokines and oxidative substances, and reduced apoptotic cells in methionine/choline-deficient diet (MCDD)-fed mice. In conclusion, we demonstrated that Parp-1 promoted iPSC generation from senescent cells, which can be used for the treatment of NASH after hepatic-specific differentiation. These findings indicated that patient-derived iPSC-Heps may offer an alternative option for treatment of NASH and NASH-associated end-stage liver diseases.
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Affiliation(s)
- Yueh Chien
- Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan, ROC.,Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Chi-Shuan Huang
- Division of Colorectal Surgery, Department of Surgery, Cheng-Hsin General Hospital, Taipei, Taiwan, ROC
| | - Hsin-Chi Lin
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC.,School of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Kai-Hsi Lu
- Department of Medical Research and Education, Cheng-Hsin General Hospital, Taipei, Taiwan, ROC
| | - Ping-Hsing Tsai
- Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan, ROC.,Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Ying-Hsiu Lai
- Department of Medical Research and Education, Cheng-Hsin General Hospital, Taipei, Taiwan, ROC
| | - Kuan-Hsuan Chen
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan, ROC.,Department of Pharmacy, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Shou-Dong Lee
- Division of Gastroenterology, Department of Internal Medicine, Cheng-Hsin General Hospital, Taipei, Taiwan, ROC.,Division of Gastroenterology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Yi-Hsiang Huang
- Division of Gastroenterology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Chien-Ying Wang
- School of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC.,Division of Trauma, Department of Emergency Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
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12
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Zhou L, Yin P, Luo P, Tang L, Wang Z, Gao P, Piao H, Lu X, Xu G. High-throughput metabolic profiling based on small amount of hepatic cells. Electrophoresis 2017; 38:2296-2303. [DOI: 10.1002/elps.201600539] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 04/17/2017] [Accepted: 04/18/2017] [Indexed: 12/27/2022]
Affiliation(s)
- Lina Zhou
- Key Laboratory of Separation Science for Analytical Chemistry; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian P. R. China
| | - Peiyuan Yin
- Key Laboratory of Separation Science for Analytical Chemistry; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian P. R. China
| | - Ping Luo
- Key Laboratory of Separation Science for Analytical Chemistry; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian P. R. China
| | - Ling Tang
- Key Laboratory of Separation Science for Analytical Chemistry; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian P. R. China
| | - Zhichao Wang
- Key Laboratory of Separation Science for Analytical Chemistry; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian P. R. China
| | - Peng Gao
- Key Laboratory of Separation Science for Analytical Chemistry; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian P. R. China
| | - Hailong Piao
- Key Laboratory of Separation Science for Analytical Chemistry; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian P. R. China
| | - Xin Lu
- Key Laboratory of Separation Science for Analytical Chemistry; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian P. R. China
| | - Guowang Xu
- Key Laboratory of Separation Science for Analytical Chemistry; Dalian Institute of Chemical Physics; Chinese Academy of Sciences; Dalian P. R. China
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13
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Im AR, Kim YH, Lee HW, Song KH. Water Extract of Dolichos lablab Attenuates Hepatic Lipid Accumulation in a Cellular Nonalcoholic Fatty Liver Disease Model. J Med Food 2017; 19:495-503. [PMID: 27152979 DOI: 10.1089/jmf.2015.3623] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease that is rising in prevalence worldwide. Therapeutic strategies for patients with NAFLD are limited by a lack of effective drugs. In this report, we show that Dolichos lablab water extract (DLL-Ex) protects against free fatty acid (FFA)-induced lipid accumulation and attenuates expression of genes involved in lipid droplet accumulation in cellular NAFLD models. The hepatoprotective effects and underlying mechanism of DLL-Ex were assessed using an in vitro cellular model in which NAFLD was simulated by inducing excessive FFA influx into hepatocytes. HepG2 cells were treated with DLL-Ex and FFAs for 24 h, after which intracellular lipid content was observed by using Nile Red and Oil Red O staining. Quantitative real-time polymerase chain reaction was used to measure expression levels of genes related to FFA-mediated cellular energy depletion. Western blotting was used to measure protein levels of phosphorylated c-Jun N-terminal kinase, AMP-activated protein kinase alpha (AMPKα), and peroxisome proliferator-activated receptor γ coactivator 1 alpha. In HepG2 cells, DLL-Ex inhibited expression of CD36, which regulates fatty acid uptake, as well as BODIPY-labeled fatty acid uptake. Additionally, DLL-Ex significantly attenuated FFA-mediated cellular energy depletion and mitochondrial membrane depolarization. Furthermore, DLL-Ex enhanced phosphorylation of AMPK, indicating that AMPK is a critical regulator of DLL-Ex-mediated inhibition of hepatic lipid accumulation, possibly through its antioxidative effect. These results demonstrate that DLL-Ex exerts potent anti-NAFLD activity, suggesting that it could be a potential adjuvant treatment for patients with NAFLD.
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Affiliation(s)
- A-Rang Im
- 1 KM Convergence Research Division, Korea Institute of Oriental Medicine , Daejeon, Korea
| | - Yun Hee Kim
- 1 KM Convergence Research Division, Korea Institute of Oriental Medicine , Daejeon, Korea
| | - Hye Won Lee
- 1 KM Convergence Research Division, Korea Institute of Oriental Medicine , Daejeon, Korea
| | - Kwang Hoon Song
- 2 Mibyeong Research Center, Korea Institute of Oriental Medicine , Daejeon, Korea.,3 University of Science and Technology , Daejeon, Korea
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14
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Hepatic FTO expression is increased in NASH and its silencing attenuates palmitic acid-induced lipotoxicity. Biochem Biophys Res Commun 2016; 479:476-481. [PMID: 27651333 DOI: 10.1016/j.bbrc.2016.09.086] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 09/16/2016] [Indexed: 11/20/2022]
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15
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Xu S, Nam SM, Kim JH, Das R, Choi SK, Nguyen TT, Quan X, Choi SJ, Chung CH, Lee EY, Lee IK, Wiederkehr A, Wollheim CB, Cha SK, Park KS. Palmitate induces ER calcium depletion and apoptosis in mouse podocytes subsequent to mitochondrial oxidative stress. Cell Death Dis 2015; 6:e1976. [PMID: 26583319 PMCID: PMC4670935 DOI: 10.1038/cddis.2015.331] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 10/02/2015] [Accepted: 10/12/2015] [Indexed: 12/14/2022]
Abstract
Pathologic alterations in podocytes lead to failure of an essential component of the glomerular filtration barrier and proteinuria in chronic kidney diseases. Elevated levels of saturated free fatty acid (FFA) are harmful to various tissues, implemented in the progression of diabetes and its complications such as proteinuria in diabetic nephropathy. Here, we investigated the molecular mechanism of palmitate cytotoxicity in cultured mouse podocytes. Incubation with palmitate dose-dependently increased cytosolic and mitochondrial reactive oxygen species, depolarized the mitochondrial membrane potential, impaired ATP synthesis and elicited apoptotic cell death. Palmitate not only evoked mitochondrial fragmentation but also caused marked dilation of the endoplasmic reticulum (ER). Consistently, palmitate upregulated ER stress proteins, oligomerized stromal interaction molecule 1 (STIM1) in the subplasmalemmal ER membrane, abolished the cyclopiazonic acid-induced cytosolic Ca2+ increase due to depletion of luminal ER Ca2+. Palmitate-induced ER Ca2+ depletion and cytotoxicity were blocked by a selective inhibitor of the fatty-acid transporter FAT/CD36. Loss of the ER Ca2+ pool induced by palmitate was reverted by the phospholipase C (PLC) inhibitor edelfosine. Palmitate-dependent activation of PLC was further demonstrated by following cytosolic translocation of the pleckstrin homology domain of PLC in palmitate-treated podocytes. An inhibitor of diacylglycerol (DAG) kinase, which elevates cytosolic DAG, strongly promoted ER Ca2+ depletion by low-dose palmitate. GF109203X, a PKC inhibitor, partially prevented palmitate-induced ER Ca2+ loss. Remarkably, the mitochondrial antioxidant mitoTEMPO inhibited palmitate-induced PLC activation, ER Ca2+ depletion and cytotoxicity. Palmitate elicited cytoskeletal changes in podocytes and increased albumin permeability, which was also blocked by mitoTEMPO. These data suggest that oxidative stress caused by saturated FFA leads to mitochondrial dysfunction and ER Ca2+ depletion through FAT/CD36 and PLC signaling, possibly contributing to podocyte injury.
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Affiliation(s)
- S Xu
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - S M Nam
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.,Department of Internal Medicine, Daejeon Sun Hospital, Daejeon, Korea
| | - J-H Kim
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - R Das
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - S-K Choi
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - T T Nguyen
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - X Quan
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - S J Choi
- Department of Microbiology, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - C H Chung
- Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - E Y Lee
- Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan, Korea
| | - I-K Lee
- Department of Internal Medicine, Kyungpook National University Hospital, Daegu, Korea
| | - A Wiederkehr
- Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - C B Wollheim
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - S-K Cha
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - K-S Park
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
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16
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Choi K, Ortega MT, Jeffery B, Riviere JE, Monteiro-Riviere NA. Oxidative stress response in canine in vitro liver, kidney and intestinal models with seven potential dietary ingredients. Toxicol Lett 2015; 241:49-59. [PMID: 26602166 DOI: 10.1016/j.toxlet.2015.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/13/2015] [Accepted: 11/13/2015] [Indexed: 02/07/2023]
Abstract
In vitro cell culture systems are a useful tool to rapidly assess the potential safety or toxicity of chemical constituents of food. Here, we investigated oxidative stress and organ-specific antioxidant responses by 7 potential dietary ingredients using canine in vitro culture of hepatocytes, proximal tubule cells (CPTC), bone marrow-derived mesenchymal stem cells (BMSC) and enterocyte-like cells (ELC). Cellular production of free radical species by denatonium benzoate (DB), epigallocatechin gallate (EPI), eucalyptol (EUC), green tea catechin extract (GTE) and sodium copper chlorophyllin (SCC), tetrahydroisohumulone (TRA) as well as xylitol (XYL) were continuously measured for reactive oxygen/nitrogen species (ROS/RNS) and superoxide (SO) for up to 24h. DB and TRA showed strong prooxidant activities in hepatocytes and to a lesser degree in ELC. DB was a weak prooxidant in BMSC. In contrast DB and TRA were antioxidants in CPTC. EPI was prooxidant in hepatocytes and BMSC but showed prooxidant and antioxidant activity in CPTC. SCC in hepatocytes (12.5mg/mL) and CPTC (0.78mg/mL) showed strong prooxidant and antioxidant activity in a concentration-dependent manner. GTE was effective antioxidant only in ELC. EUC and XYL did not induce ROS/RNS in all 4 cell types. SO production by EPI and TRA increased in hepatocytes but decreased by SCC in hepatocytes and ELC. These results suggest that organ-specific responses to oxidative stress by these potential prooxidant compounds may implicate a mechanism of their toxicities.
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Affiliation(s)
- Kyoungju Choi
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
| | - Maria T Ortega
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
| | - Brett Jeffery
- Mars Global Food Safety Center, Yanqi Economic Development Zone, Huairou, Beijing, P.R. China
| | - Jim E Riviere
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
| | - Nancy A Monteiro-Riviere
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States.
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17
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Abstract
SIGNIFICANCE Cardiac function is energetically demanding, reliant on efficient well-coupled mitochondria to generate adenosine triphosphate and fulfill the cardiac demand. Predictably then, mitochondrial dysfunction is associated with cardiac pathologies, often related to metabolic disease, most commonly diabetes. Diabetic cardiomyopathy (DCM), characterized by decreased left ventricular function, arises independently of coronary artery disease and atherosclerosis. Dysregulation of Ca(2+) handling, metabolic changes, and oxidative stress are observed in DCM, abnormalities reflected in alterations in mitochondrial energetics. Cardiac tissue from DCM patients also presents with altered mitochondrial morphology, suggesting a possible role of mitochondrial dynamics in its pathological progression. RECENT ADVANCES Abnormal mitochondrial morphology is associated with pathologies across diverse tissues, suggesting that this highly regulated process is essential for proper cell maintenance and physiological homeostasis. Highly structured cardiac myofibers were hypothesized to limit alterations in mitochondrial morphology; however, recent work has identified morphological changes in cardiac tissue, specifically in DCM. CRITICAL ISSUES Mitochondrial dysfunction has been reported independently from observations of altered mitochondrial morphology in DCM. The temporal relationship and causative nature between functional and morphological changes of mitochondria in the establishment/progression of DCM is unclear. FUTURE DIRECTIONS Altered mitochondrial energetics and morphology are not only causal for but also consequential to reactive oxygen species production, hence exacerbating oxidative damage through reciprocal amplification, which is integral to the progression of DCM. Therefore, targeting mitochondria for DCM will require better mechanistic characterization of morphological distortion and bioenergetic dysfunction.
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Affiliation(s)
- Chad A Galloway
- 1Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Yisang Yoon
- 2Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
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18
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Schaller S, Michaud M, Latyszenok V, Robert F, Hocine M, Arnoux T, Gabriac M, Codoul H, Bourhane A, de Bellefois IC, Afxantidis J, Pruss RM. TRO40303, a mitochondrial-targeted cytoprotective compound, provides protection in hepatitis models. Pharmacol Res Perspect 2015; 3:e00144. [PMID: 26236486 PMCID: PMC4492760 DOI: 10.1002/prp2.144] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 03/17/2015] [Indexed: 01/05/2023] Open
Abstract
TRO40303 is cytoprotective compound that was shown to reduce infarct size in preclinical models of myocardial infarction. It targets mitochondria, delays mitochondrial permeability transition pore (mPTP) opening and reduces oxidative stress in cardiomyocytes submitted to ischemia/reperfusion in vitro. Because the involvement of the mitochondria and the mPTP has been demonstrated in chronic as well as acute hepatitis, we investigated the potential of TRO40303 to prevent hepatocyte injury. A first set of in vitro studies showed that TRO40303 (from 0.3 to 3 μmol/L) protected HepG2 cells and primary mouse embryonic hepatocytes (PMEH) from palmitate intoxication, a model mimicking steatohepatitis. In PMEH, TRO40303 provided similar protection against cell death due to Jo2 anti-Fas antibody intoxication. Further studies were then preformed in a mouse model of Fas-induced fulminant hepatitis induced by injecting Jo2 anti-Fas antibody. When mice received a sublethal dose of Jo2 at 125 μg/kg, TRO40303 pretreatment prevented liver enzyme elevation in plasma in parallel with a decrease in cytochrome C release from mitochondria and caspase 3 and 7 activation in hepatic tissue. When higher, lethal doses of Jo2 were administered, TRO40303 (10 and 30 mg/kg) significantly reduced mortality by 65–90% when administered intraperitoneally (i.p.) 1 h before Jo2 injection, a time when TRO40303 plasma concentrations reached their peak. TRO40303 (30 mg/kg, i.p.) was also able to reduce mortality by 30–50% when administered 1 h postlethal Jo2 intoxication. These results suggest that TRO40303 could be a promising new therapy for the treatment or prevention of hepatitis.
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Affiliation(s)
| | - Magali Michaud
- Trophos S. A., Luminy Biotech Entreprise Marseille, France
| | | | - Fabrice Robert
- Trophos S. A., Luminy Biotech Entreprise Marseille, France
| | - Mélanie Hocine
- Trophos S. A., Luminy Biotech Entreprise Marseille, France
| | - Thomas Arnoux
- Trophos S. A., Luminy Biotech Entreprise Marseille, France
| | | | - Hélène Codoul
- Trophos S. A., Luminy Biotech Entreprise Marseille, France
| | - Ahmed Bourhane
- Trophos S. A., Luminy Biotech Entreprise Marseille, France
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19
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Ueda N. Ceramide-induced apoptosis in renal tubular cells: a role of mitochondria and sphingosine-1-phoshate. Int J Mol Sci 2015; 16:5076-124. [PMID: 25751724 PMCID: PMC4394466 DOI: 10.3390/ijms16035076] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 02/09/2015] [Accepted: 02/12/2015] [Indexed: 12/16/2022] Open
Abstract
Ceramide is synthesized upon stimuli, and induces apoptosis in renal tubular cells (RTCs). Sphingosine-1 phosphate (S1P) functions as a survival factor. Thus, the balance of ceramide/S1P determines ceramide-induced apoptosis. Mitochondria play a key role for ceramide-induced apoptosis by altered mitochondrial outer membrane permeability (MOMP). Ceramide enhances oligomerization of pro-apoptotic Bcl-2 family proteins, ceramide channel, and reduces anti-apoptotic Bcl-2 proteins in the MOM. This process alters MOMP, resulting in generation of reactive oxygen species (ROS), cytochrome C release into the cytosol, caspase activation, and apoptosis. Ceramide regulates apoptosis through mitogen-activated protein kinases (MAPKs)-dependent and -independent pathways. Conversely, MAPKs alter ceramide generation by regulating the enzymes involving ceramide metabolism, affecting ceramide-induced apoptosis. Crosstalk between Bcl-2 family proteins, ROS, and many signaling pathways regulates ceramide-induced apoptosis. Growth factors rescue ceramide-induced apoptosis by regulating the enzymes involving ceramide metabolism, S1P, and signaling pathways including MAPKs. This article reviews evidence supporting a role of ceramide for apoptosis and discusses a role of mitochondria, including MOMP, Bcl-2 family proteins, ROS, and signaling pathways, and crosstalk between these factors in the regulation of ceramide-induced apoptosis of RTCs. A balancing role between ceramide and S1P and the strategy for preventing ceramide-induced apoptosis by growth factors are also discussed.
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Affiliation(s)
- Norishi Ueda
- Department of Pediatrics, Public Central Hospital of Matto Ishikawa, 3-8 Kuramitsu, Hakusan, Ishikawa 924-8588, Japan.
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20
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Paradies G, Paradies V, Ruggiero FM, Petrosillo G. Oxidative stress, cardiolipin and mitochondrial dysfunction in nonalcoholic fatty liver disease. World J Gastroenterol 2014; 20:14205-18. [PMID: 25339807 PMCID: PMC4202349 DOI: 10.3748/wjg.v20.i39.14205] [Citation(s) in RCA: 317] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 02/13/2014] [Accepted: 06/26/2014] [Indexed: 02/06/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is today considered the most common form of chronic liver disease, affecting a high proportion of the population worldwide. NAFLD encompasses a large spectrum of liver damage, ranging from simple steatosis to steatohepatitis, advanced fibrosis and cirrhosis. Obesity, hyperglycemia, type 2 diabetes and hypertriglyceridemia are the most important risk factors. The pathogenesis of NAFLD and its progression to fibrosis and chronic liver disease is still unknown. Accumulating evidence indicates that mitochondrial dysfunction plays a key role in the physiopathology of NAFLD, although the mechanisms underlying this dysfunction are still unclear. Oxidative stress is considered an important factor in producing lethal hepatocyte injury associated with NAFLD. Mitochondrial respiratory chain is the main subcellular source of reactive oxygen species (ROS), which may damage mitochondrial proteins, lipids and mitochondrial DNA. Cardiolipin, a phospholipid located at the level of the inner mitochondrial membrane, plays an important role in several reactions and processes involved in mitochondrial bioenergetics as well as in mitochondrial dependent steps of apoptosis. This phospholipid is particularly susceptible to ROS attack. Cardiolipin peroxidation has been associated with mitochondrial dysfunction in multiple tissues in several physiopathological conditions, including NAFLD. In this review, we focus on the potential roles played by oxidative stress and cardiolipin alterations in mitochondrial dysfunction associated with NAFLD.
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21
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Cadavez L, Montane J, Alcarraz-Vizán G, Visa M, Vidal-Fàbrega L, Servitja JM, Novials A. Chaperones ameliorate beta cell dysfunction associated with human islet amyloid polypeptide overexpression. PLoS One 2014; 9:e101797. [PMID: 25010593 PMCID: PMC4092029 DOI: 10.1371/journal.pone.0101797] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/10/2014] [Indexed: 12/14/2022] Open
Abstract
In type 2 diabetes, beta-cell dysfunction is thought to be due to several causes, one being the formation of toxic protein aggregates called islet amyloid, formed by accumulations of misfolded human islet amyloid polypeptide (hIAPP). The process of hIAPP misfolding and aggregation is one of the factors that may activate the unfolded protein response (UPR), perturbing endoplasmic reticulum (ER) homeostasis. Molecular chaperones have been described to be important in regulating ER response to ER stress. In the present work, we evaluate the role of chaperones in a stressed cellular model of hIAPP overexpression. A rat pancreatic beta-cell line expressing hIAPP exposed to thapsigargin or treated with high glucose and palmitic acid, both of which are known ER stress inducers, showed an increase in ER stress genes when compared to INS1E cells expressing rat IAPP or INS1E control cells. Treatment with molecular chaperone glucose-regulated protein 78 kDa (GRP78, also known as BiP) or protein disulfite isomerase (PDI), and chemical chaperones taurine-conjugated ursodeoxycholic acid (TUDCA) or 4-phenylbutyrate (PBA), alleviated ER stress and increased insulin secretion in hIAPP-expressing cells. Our results suggest that the overexpression of hIAPP induces a stronger response of ER stress markers. Moreover, endogenous and chemical chaperones are able to ameliorate induced ER stress and increase insulin secretion, suggesting that improving chaperone capacity can play an important role in improving beta-cell function in type 2 diabetes.
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Affiliation(s)
- Lisa Cadavez
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic de Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Joel Montane
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic de Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Gema Alcarraz-Vizán
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic de Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Montse Visa
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic de Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Laia Vidal-Fàbrega
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic de Barcelona, Spain
| | - Joan-Marc Servitja
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic de Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Anna Novials
- Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic de Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
- * E-mail:
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22
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Lee MH, Jeon HM, Han JH, Park N, Kang C, Sessler JL, Kim JS. Toward a chemical marker for inflammatory disease: a fluorescent probe for membrane-localized thioredoxin. J Am Chem Soc 2014; 136:8430-7. [PMID: 24840911 PMCID: PMC4227802 DOI: 10.1021/ja503356q] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
![]()
Thioredoxin
(Trx) is a redox-active protein that plays a key role
in mitigating the effects of oxidative stress. The secretion of Trx
on the plasma membrane has been suggested as a distinctive feature
of inflammation. However, selective monitoring of membrane-associated
Trx activity has proved challenging because of the ubiquity of Trx
action in cells. Here, we report a Trx-specific probe that allows
visualization of Trx activity associated with the membranes via fluorescence
microscopy. The ability of this probe to act as a possible screening
tool for agents that modulate Trx secretion was demonstrated in HeLa
cells under oxidative stress conditions and in a cellular hepatosteatosis
model. Control experiments serve to confirm that the response seen
for the present probe is due to Trx and that it is selective over
various potentially competing metabolites, including thiol-containing
small molecules and test proteins.
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Affiliation(s)
- Min Hee Lee
- Department of Chemistry, The University of Texas at Austin , Austin, Texas 78712-1224, United States
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The production of nitric oxide, IL-6, and TNF-alpha in palmitate-stimulated PBMNCs is enhanced through hyperglycemia in diabetes. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2014; 2014:479587. [PMID: 24803982 PMCID: PMC3997868 DOI: 10.1155/2014/479587] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 03/01/2014] [Indexed: 01/22/2023]
Abstract
We examined nitric oxide (NO), IL-6, and TNF-α secretion from cultured palmitate-stimulated PBMNCs or in the plasma from type 2 diabetes mellitus (T2MD) patients or nondiabetic (ND) controls. Free fatty acids (FFA) have been suggested to induce chronic low-grade inflammation, activate the innate immune system, and cause deleterious effects on vascular cells and other tissues through inflammatory processes. The levels of NO, IL-6, TNF-α, and MDA were higher in supernatant of palmitate stimulated blood cells (PBMNC) or from plasma from patients. The results obtained in the present study demonstrated that hyperglycemia in diabetes exacerbates in vitro inflammatory responses in PBMNCs stimulated with high levels of SFA (palmitate). These results suggest that hyperglycemia primes PBMNCs for NO, IL-6, and TNF-alpha secretion under in vitro FFA stimulation are associated with the secretion of inflammatory biomarkers in diabetes. A combined therapy targeting signaling pathways activated by hyperglycemia in conjunction with simultaneous control of hyperglycemia and hypertriglyceridemia would be suggested for controlling the progress of diabetic complications.
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Egnatchik RA, Leamy AK, Noguchi Y, Shiota M, Young JD. Palmitate-induced activation of mitochondrial metabolism promotes oxidative stress and apoptosis in H4IIEC3 rat hepatocytes. Metabolism 2014; 63:283-95. [PMID: 24286856 PMCID: PMC3946971 DOI: 10.1016/j.metabol.2013.10.009] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 09/19/2013] [Accepted: 10/20/2013] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Hepatic lipotoxicity is characterized by reactive oxygen species (ROS) accumulation, mitochondrial dysfunction, and excessive apoptosis, but the precise sequence of biochemical events leading to oxidative damage and cell death remains unclear. The goal of this study was to delineate the role of mitochondrial metabolism in mediating hepatocyte lipotoxicity. MATERIALS/METHODS We treated H4IIEC3 rat hepatoma cells with free fatty acids in combination with antioxidants and mitochondrial inhibitors designed to block key events in the progression toward apoptosis. We then applied (13)C metabolic flux analysis (MFA) to quantify mitochondrial pathway alterations associated with these treatments. RESULTS Treatment with palmitate alone led to a doubling in oxygen uptake rate and in most mitochondrial fluxes. Supplementing culture media with the antioxidant N-acetyl-cysteine (NAC) reduced ROS accumulation and caspase activation and partially restored cell viability. However, (13)C MFA revealed that treatment with NAC did not normalize palmitate-induced metabolic alterations, indicating that neither elevated ROS nor downstream apoptotic events contributed to mitochondrial activation. To directly limit mitochondrial metabolism, the complex I inhibitor phenformin was added to cells treated with palmitate. Phenformin addition eliminated abnormal ROS accumulation, prevented the appearance of apoptotic markers, and normalized mitochondrial carbon flow. Further studies revealed that glutamine provided the primary fuel for elevated mitochondrial metabolism in the presence of palmitate, rather than fatty acid beta-oxidation, and that glutamine consumption could be reduced through co-treatment with phenformin but not NAC. CONCLUSION Our results indicate that ROS accumulation in palmitate-treated H4IIEC3 cells occurs downstream of altered mitochondrial oxidative metabolism, which is independent of beta-oxidation and precedes apoptosis initiation.
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Affiliation(s)
- Robert A Egnatchik
- Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA
| | - Alexandra K Leamy
- Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA
| | - Yasushi Noguchi
- Institute for Innovation, Ajinomoto Co., Inc., Kawasaki, Japan
| | - Masakazu Shiota
- Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Jamey D Young
- Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA; Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA.
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25
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García-Ruiz C, Baulies A, Mari M, García-Rovés PM, Fernandez-Checa JC. Mitochondrial dysfunction in non-alcoholic fatty liver disease and insulin resistance: Cause or consequence? Free Radic Res 2013; 47:854-68. [DOI: 10.3109/10715762.2013.830717] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Arany I, Clark JS, Reed DK, Juncos LA, Dixit M. Role of p66shc in renal toxicity of oleic acid. Am J Nephrol 2013; 38:226-32. [PMID: 23988748 DOI: 10.1159/000354357] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 07/11/2013] [Indexed: 01/09/2023]
Abstract
BACKGROUND/AIMS Adult and childhood obesity is an independent risk factor in development of chronic kidney disease (CKD) and its progression to end-stage kidney disease. Pathologic consequences of obesity include non-esterified fatty acid-induced oxidative stress and consequent injury. Since the serine36-phosphorylated p66shc is a newly recognized mediator of oxidative stress and kidney injury, we studied its role in oleic acid (OA)-induced production of reactive oxygen species (ROS), mitochondrial depolarization and injury in cultured renal proximal tubule cells. METHODS Renal proximal tubule cells were used and treated with OA: ROS production, mitochondrial depolarization as well as injury were determined. Transcriptional effects of OA on the p66shc gene were determined in a reporter luciferase assay. The role of p66shc in adverse effects of OA was determined using knockdown, p66shc serine36 phosphorylation and cytochrome c binding-deficient cells. RESULTS We found that OA increased ROS production via the mitochondria - and to a less extent via the NADPH oxidase - resulting in ROS-dependent mitochondrial depolarization and consequent injury. Interestingly, OA also stimulated the promoter of p66shc. Hence, knockdown of p66shc, impairment its Ser36 phosphorylation (mutation of Ser36 residue to alanine) or cytochrome c binding (W134F mutation) significantly attenuated OA-dependent lipotoxicity. CONCLUSION These results offer a novel mechanism by which obesity may lead to renal tubular injury and consequently development of CKD. Manipulation of this pathway may offer therapeutic means to ameliorate obesity-dependent renal lipotoxicity.
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Affiliation(s)
- Istvan Arany
- Division of Pediatric Nephrology, Department of Pediatrics, University of Mississippi Medical Center, Jackson, MO 39110, USA.
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Abstract
SIGNIFICANCE Mitochondria are the cellular energy-producing organelles and are at the crossroad of determining cell life and death. As such, the function of mitochondria has been intensely studied in metabolic disorders, including diabetes and associated maladies commonly grouped under all-inclusive pathological condition of metabolic syndrome. More recently, the altered metabolic profiles and function of mitochondria in these ailments have been correlated with their aberrant morphologies. This review describes an overview of mitochondrial fission and fusion machineries, and discusses implications of mitochondrial morphology and function in these metabolic maladies. RECENT ADVANCES Mitochondria undergo frequent morphological changes, altering the mitochondrial network organization in response to environmental cues, termed mitochondrial dynamics. Mitochondrial fission and fusion mediate morphological plasticity of mitochondria and are controlled by membrane-remodeling mechanochemical enzymes and accessory proteins. Growing evidence suggests that mitochondrial dynamics play an important role in diabetes establishment and progression as well as associated ailments, including, but not limited to, metabolism-secretion coupling in the pancreas, nonalcoholic fatty liver disease progression, and diabetic cardiomyopathy. CRITICAL ISSUES While mitochondrial dynamics are intimately associated with mitochondrial bioenergetics, their cause-and-effect correlation remains undefined in metabolic diseases. FUTURE DIRECTIONS The involvement of mitochondrial dynamics in metabolic diseases is in its relatively early stages. Elucidating the role of mitochondrial dynamics in pathological metabolic conditions will aid in defining the intricate form-function correlation of mitochondria in metabolic pathologies and should provide not only important clues to metabolic disease progression, but also new therapeutic targets.
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Affiliation(s)
- Chad A Galloway
- Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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Esposito G, Vos M, Vilain S, Swerts J, De Sousa Valadas J, Van Meensel S, Schaap O, Verstreken P. Aconitase causes iron toxicity in Drosophila pink1 mutants. PLoS Genet 2013; 9:e1003478. [PMID: 23637640 PMCID: PMC3636082 DOI: 10.1371/journal.pgen.1003478] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 03/12/2013] [Indexed: 12/21/2022] Open
Abstract
The PTEN-induced kinase 1 (PINK1) is a mitochondrial kinase, and pink1 mutations cause early onset Parkinson's disease (PD) in humans. Loss of pink1 in Drosophila leads to defects in mitochondrial function, and genetic data suggest that another PD-related gene product, Parkin, acts with pink1 to regulate the clearance of dysfunctional mitochondria (mitophagy). Consequently, pink1 mutants show an accumulation of morphologically abnormal mitochondria, but it is unclear if other factors are involved in pink1 function in vivo and contribute to the mitochondrial morphological defects seen in specific cell types in pink1 mutants. To explore the molecular mechanisms of pink1 function, we performed a genetic modifier screen in Drosophila and identified aconitase (acon) as a dominant suppressor of pink1. Acon localizes to mitochondria and harbors a labile iron-sulfur [4Fe-4S] cluster that can scavenge superoxide to release hydrogen peroxide and iron that combine to produce hydroxyl radicals. Using Acon enzymatic mutants, and expression of mitoferritin that scavenges free iron, we show that [4Fe-4S] cluster inactivation, as a result of increased superoxide in pink1 mutants, results in oxidative stress and mitochondrial swelling. We show that [4Fe-4S] inactivation acts downstream of pink1 in a pathway that affects mitochondrial morphology, but acts independently of parkin. Thus our data indicate that superoxide-dependent [4Fe-4S] inactivation defines a potential pathogenic cascade that acts independent of mitophagy and links iron toxicity to mitochondrial failure in a PD–relevant model. In this work we provide mechanistic insight linking together two of the earliest observations in Parkinson's disease: the excessive build-up of iron in diseased substantia nigra neurons and mitochondrial dysfunction particularly increased reactive oxygen species production at the level of Complex I. We identify aconitase mutants as strong genetic suppressors of Parkinson-related pink1 mutant phenotypes, both at the organismal and at the cellular/mitochondrial level. We show that the mitochondrial dysfunction in pink1 mutants that includes Complex I dysfunction results in superoxide-dependent inactivation of the Aconitase iron-sulfur cluster, leading to the release of iron and peroxide that combine to produce hydroxyl radicals and mitochondrial failure. Consequently, scavenging free iron using expression of mitoferritin or decreasing the levels of aconitase both rescue pink1 mutants; while increased wild-type Aconitase, but not a mutant that does not harbor an iron-sulfur cluster, results in severe mitochondrial defects. Given that reduced electron transport chain activity, increased oxidative stress, and natural iron build-up in the substantia nigra are common factors in sporadic and familial forms of Parkinson's disease, we believe that oxidative inactivation of Aconitase may represent an important pathogenic cascade underlying neuronal dysfunction in Parkinson's disease.
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Affiliation(s)
- Giovanni Esposito
- VIB Center for the Biology of Disease, Leuven, Belgium
- KU Leuven, Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium
| | - Melissa Vos
- VIB Center for the Biology of Disease, Leuven, Belgium
- KU Leuven, Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium
| | - Sven Vilain
- VIB Center for the Biology of Disease, Leuven, Belgium
- KU Leuven, Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium
| | - Jef Swerts
- VIB Center for the Biology of Disease, Leuven, Belgium
- KU Leuven, Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium
| | - Jorge De Sousa Valadas
- VIB Center for the Biology of Disease, Leuven, Belgium
- KU Leuven, Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium
| | - Stefanie Van Meensel
- VIB Center for the Biology of Disease, Leuven, Belgium
- KU Leuven, Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium
| | - Onno Schaap
- VIB Center for the Biology of Disease, Leuven, Belgium
- KU Leuven, Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium
| | - Patrik Verstreken
- VIB Center for the Biology of Disease, Leuven, Belgium
- KU Leuven, Center for Human Genetics and Leuven Research Institute for Neuroscience and Disease (LIND), Leuven, Belgium
- * E-mail:
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Cho H, Wu M, Zhang L, Thompson R, Nath A, Chan C. Signaling dynamics of palmitate-induced ER stress responses mediated by ATF4 in HepG2 cells. BMC SYSTEMS BIOLOGY 2013; 7:9. [PMID: 23339444 PMCID: PMC3557202 DOI: 10.1186/1752-0509-7-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 01/17/2013] [Indexed: 11/21/2022]
Abstract
Background Palmitic acid, the most common saturated free fatty acid, has been implicated in ER (endoplasmic reticulum) stress-mediated apoptosis. This lipoapotosis is dependent, in part, on the upregulation of the activating transcription factor-4 (ATF4). To better understand the mechanisms by which palmitate upregulates the expression level of ATF4, we integrated literature information on palmitate-induced ER stress signaling into a discrete dynamic model. The model provides an in silico framework that enables simulations and predictions. The model predictions were confirmed through further experiments in human hepatocellular carcinoma (HepG2) cells and the results were used to update the model and our current understanding of the signaling induced by palmitate. Results The three key things from the in silico simulation and experimental results are: 1) palmitate induces different signaling pathways (PKR (double-stranded RNA-activated protein kinase), PERK (PKR-like ER kinase), PKA (cyclic AMP (cAMP)-dependent protein kinase A) in a time dependent-manner, 2) both ATF4 and CREB1 (cAMP-responsive element-binding protein 1) interact with the Atf4 promoter to contribute to a prolonged accumulation of ATF4, and 3) CREB1 is involved in ER-stress induced apoptosis upon palmitate treatment, by regulating ATF4 expression and possibly Ca2+ dependent-CaM (calmodulin) signaling pathway. Conclusion The in silico model helped to delineate the essential signaling pathways in palmitate-mediated apoptosis.
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Affiliation(s)
- Hyunju Cho
- Department of Chemical Engineering and Materials Science, East Lansing, MI 48824, USA
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30
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Kwan HY, Fong WF, Yang Z, Yu ZL, Hsiao WLW. Inhibition of DNA-dependent protein kinase reduced palmitate and oleate-induced lipid accumulation in HepG2 cells. Eur J Nutr 2012. [DOI: 10.1007/s00394-012-0467-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Sharma M, Gadang V, Jaeschke A. Critical role for mixed-lineage kinase 3 in acetaminophen-induced hepatotoxicity. Mol Pharmacol 2012; 82:1001-7. [PMID: 22918968 PMCID: PMC3477232 DOI: 10.1124/mol.112.079863] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 08/23/2012] [Indexed: 12/13/2022] Open
Abstract
c-Jun NH(2)-terminal kinase (JNK) activation plays a major role in acetaminophen (APAP)-induced hepatotoxicity. However, the exact mechanism of APAP-induced JNK activation is incompletely understood. It has been established that apoptosis signal-regulating kinase 1 (ASK1) regulates the late phase of APAP-induced JNK activation, but the mitogen-activated protein kinase kinase kinase that mediates the initial phase of APAP-induced JNK activation has not been identified. Oxidative stress produced during APAP metabolism causes JNK activation, which promotes mitochondrial dysfunction and results in the amplification of oxidative stress. Therefore, inhibition of the initial phase of JNK activation may be key to protection against APAP-induced liver injury. The goal of this study was to determine whether mixed-lineage kinase 3 (MLK3) mediates the initial, ASK1-independent phase of APAP-induced JNK activation and thus promotes drug-induced hepatotoxicity. We found that MLK3 was activated by oxidative stress and was required for JNK activation in response to oxidative stress. Loss of MLK3 attenuated APAP-induced JNK activation and hepatocyte death in vitro, independent of receptor-interacting protein 1. Moreover, JNK and glycogen synthase kinase 3β activation was significantly attenuated, and Mcl-1 degradation was inhibited in APAP-treated MLK3-knockout mice. Furthermore, we showed that loss of MLK3 increased expression of glutamate cysteine ligase, accelerated hepatic GSH recovery, and decreased production of reactive oxygen species after APAP treatment. MLK3-deficient mice were significantly protected from APAP-induced liver injury, compared with wild-type mice. Together, these studies establish a novel role for MLK3 in APAP-induced JNK activation and hepatotoxicity, and they suggest MLK3 as a possible target in the treatment of APAP-induced liver injury.
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Affiliation(s)
- Manju Sharma
- Department of Pathology, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio 45237, USA
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Babenko NA, Hassouneh LKM, Kharchenko VS, Garkavenko VV. Vitamin E prevents the age-dependent and palmitate-induced disturbances of sphingolipid turnover in liver cells. AGE (DORDRECHT, NETHERLANDS) 2012; 34:905-15. [PMID: 21796379 PMCID: PMC3682064 DOI: 10.1007/s11357-011-9288-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 07/04/2011] [Indexed: 05/31/2023]
Abstract
Sphingolipid turnover has been shown to be activated at old age and in response to various stress stimuli including oxidative stress. Reduction of vitamin E content in the liver under the pro-oxidant action is associated with enhanced sphingolipid turnover and ceramide accumulation in hepatocytes. In the present paper, the correction of sphingolipid metabolism in the liver cells of old rats and in the palmitate-treated young hepatocytes using α-tocopherol has been investigated. 3- and 24-month-old rats, [(14) C]palmitic acid, [methyl-(14) C-choline]sphingomyelin (SM), and [(14) C]serine were used. α-Tocopherol administration to old rats or addition to the culture medium of old liver slices or hepatocytes prevented age-dependent increase of ceramide synthesis and lipid accumulation, and increased SM content in liver tissue and cells. α-Tocopherol treatment of old cells decreased the neutral and acid sphingomyelinase (SMase) activities in hepatocytes and serine palmitoyl transferase activity in the liver cell microsomes. Effect of α- or γ-tocopherol, but not of δ-tocopherol, on the newly synthesized ceramide content in old cells was correlated with the action of inhibitor of serine palmitoyl transferase (SPT) activity (myriocin) and SMase inhibitors (glutathione, imipramine). Addition of α-tocopherol as well as myriocin to the culture medium of young hepatocytes, treated by palmitate, abolished ceramide accumulation and synthesis. The data obtained demonstrate that α-tocopherol normalized elevated ceramide content in the old liver cells via inhibition of acid and neutral SMase activities and lipid synthesis de novo. α-Tocopherol, reducing ceramide synthesis, prevented palmitate-induced aging-like ceramide accumulation in young liver cells.
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Affiliation(s)
- Nataliya A Babenko
- Department of Physiology of Ontogenesis, Institute of Biology, Kharkov Karazin National University, 4 Svobody pl., Kharkov, Ukraine.
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Luo Y, Rana P, Will Y. Cyclosporine A and palmitic acid treatment synergistically induce cytotoxicity in HepG2 cells. Toxicol Appl Pharmacol 2012; 261:172-80. [DOI: 10.1016/j.taap.2012.03.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 03/29/2012] [Accepted: 03/30/2012] [Indexed: 10/28/2022]
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Fukui M, Senmaru T, Hasegawa G, Yamazaki M, Asano M, Kagami Y, Ishigami A, Maruyama N, Iwasa K, Kitawaki J, Itoh Y, Okanoue T, Ohta M, Obayashi H, Nakamura N. 17β-Estradiol attenuates saturated fatty acid diet-induced liver injury in ovariectomized mice by up-regulating hepatic senescence marker protein-30. Biochem Biophys Res Commun 2011; 415:252-7. [DOI: 10.1016/j.bbrc.2011.10.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 10/07/2011] [Indexed: 10/16/2022]
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Ghosh S, Sulistyoningrum DC, Glier MB, Verchere CB, Devlin AM. Altered glutathione homeostasis in heart augments cardiac lipotoxicity associated with diet-induced obesity in mice. J Biol Chem 2011; 286:42483-42493. [PMID: 22021075 DOI: 10.1074/jbc.m111.304592] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Obesity-related cardiac lipid accumulation is associated with increased myocardial oxidative stress. The role of the antioxidant glutathione in cardiac lipotoxicity is unclear. Cystathionine β-synthase (Cbs) catalyzes the first step in the trans-sulfuration of homocysteine to cysteine, which is estimated to provide ∼50% of cysteine for hepatic glutathione biosynthesis. As cardiac glutathione is a reflection of the liver glutathione pool, we hypothesize that mice heterozygous for targeted disruption of Cbs (Cbs(+/-)) are more susceptible to obesity-related cardiolipotoxicity because of impaired liver glutathione synthesis. Cbs(+/+) and Cbs(+/-) mice were fed a high fat diet (60% energy) from weaning for 13 weeks to induce obesity and had similar increases in body weight and body fat. This was accompanied by increased hepatic triglyceride but no differences in hepatic glutathione levels compared with mice fed chow. However, Cbs(+/-) mice with diet-induced obesity had greater glucose intolerance and lower total and reduced glutathione levels in the heart, accompanied by lower plasma cysteine levels compared with Cbs(+/+) mice. Higher triglyceride concentrations, increased oxidative stress, and increased markers of apoptosis were also observed in heart from Cbs(+/-) mice with diet-induced obesity compared with Cbs(+/+) mice. This study suggests a novel role for Cbs in maintaining the cardiac glutathione pool and protecting against cardiac lipid accumulation and oxidative stress during diet-induced obesity in mice.
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Affiliation(s)
- Sanjoy Ghosh
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Child and Family Research Institute, Vancouver, British Columbia, V5Z 4H4, Canada
| | - Dian C Sulistyoningrum
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Child and Family Research Institute, Vancouver, British Columbia, V5Z 4H4, Canada
| | - Melissa B Glier
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Child and Family Research Institute, Vancouver, British Columbia, V5Z 4H4, Canada
| | - C Bruce Verchere
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Child and Family Research Institute, Vancouver, British Columbia, V5Z 4H4, Canada
| | - Angela M Devlin
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Child and Family Research Institute, Vancouver, British Columbia, V5Z 4H4, Canada; Department of Pediatrics, University of British Columbia, Child and Family Research Institute, Vancouver, British Columbia, V5Z 4H4, Canada.
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Gu X, Li K, Laybutt DR, He ML, Zhao HL, Chan JCN, Xu G. Bip overexpression, but not CHOP inhibition, attenuates fatty-acid-induced endoplasmic reticulum stress and apoptosis in HepG2 liver cells. Life Sci 2010; 87:724-32. [PMID: 20970436 DOI: 10.1016/j.lfs.2010.10.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 09/30/2010] [Accepted: 10/11/2010] [Indexed: 01/12/2023]
Abstract
AIMS In this study we investigated whether attenuation of endoplasmic reticulum stress (ER stress) could protect HepG2 cells from free fatty acid (FFA)-induced apoptosis. MAIN METHODS Human liver cell line HepG2 cells were exposed to Sodium Palmitate (Pa) or Sodium Oleate (Ol). Apoptosis and ER stress of HepG2 cells were analyzed with flow cytometry, real-time RT-PCR and Western Blotting. An expression plasmid encoding for the ER chaperone immunoglobulin heavy chain-binding protein (Bip) was transfected into HepG2 cells to attenuate ER stress. Small interfering RNA siCHOP was used to knockdown the expression of C/EBP Homologous Protein (CHOP) in HepG2. KEY FINDINGS Pa led to cytotoxicity and apoptosis in HepG2 cells in a dose-dependent pattern and also induced ER stress indicated by increased phosphorylation of eIF2α, upregulation of IRE1α and CHOP. Bip expression levels were slightly down regulated after Pa treatment. The unsaturated fatty acid, Ol, induced neither apoptosis nor ER stress in HepG2 cells. Overexpression of Bip attenuated Pa-induced ER stress and led to a significant reduction in Pa-mediated apoptosis, indicating a requirement of ER stress for lipotoxicity in liver cells. siRNA-mediated reduction of CHOP did not protect against Pa-induced apoptosis. SIGNIFICANCE While ER stress makes a necessary contribution to palmitate cytotoxicity, inhibition of CHOP alone is not sufficient to prevent palmitate-induced apoptosis. Our findings could advance the detailed understanding on the mechanism of high fatty acid (FFA)-induced apoptosis.
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Affiliation(s)
- Xuemei Gu
- Department of Medicine and Therapeutics, The Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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Marí M, Colell A, Morales A, von Montfort C, Garcia-Ruiz C, Fernández-Checa JC. Redox control of liver function in health and disease. Antioxid Redox Signal 2010; 12:1295-331. [PMID: 19803748 PMCID: PMC2864660 DOI: 10.1089/ars.2009.2634] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Reactive oxygen species (ROS), a heterogeneous population of biologically active intermediates, are generated as by-products of the aerobic metabolism and exhibit a dual role in biology. When produced in controlled conditions and in limited quantities, ROS may function as signaling intermediates, contributing to critical cellular functions such as proliferation, differentiation, and cell survival. However, ROS overgeneration and, particularly, the formation of specific reactive species, inflicts cell death and tissue damage by targeting vital cellular components such as DNA, lipids, and proteins, thus arising as key players in disease pathogenesis. Given the predominant role of hepatocytes in biotransformation and metabolism of xenobiotics, ROS production constitutes an important burden in liver physiology and pathophysiology and hence in the progression of liver diseases. Despite the recognized role of ROS in disease pathogenesis, the efficacy of antioxidants as therapeutics has been limited. A better understanding of the mechanisms, nature, and location of ROS generation, as well as the optimization of cellular defense strategies, may pave the way for a brighter future for antioxidants and ROS scavengers in the therapy of liver diseases.
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Affiliation(s)
- Montserrat Marí
- Liver Unit, Hospital Clinic, IDIBAPS-CIBEK, CIBEREHD, and Department of Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain
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Synergistic effect of cAMP and palmitate in promoting altered mitochondrial function and cell death in HepG2 cells. Exp Cell Res 2009; 316:716-27. [PMID: 20026039 DOI: 10.1016/j.yexcr.2009.12.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 12/07/2009] [Accepted: 12/10/2009] [Indexed: 01/19/2023]
Abstract
Saturated free fatty acids (FFAs), e.g. palmitate, have long been shown to induce toxicity and cell death in various types of cells. In this study, we demonstrate that cAMP synergistically amplifies the effect of palmitate on the induction of cell death in human hepatocellular carcinoma cell line, HepG2 cells. Elevation of cAMP level in palmitate-treated cells led to enhanced mitochondrial fragmentation, mitochondrial reactive oxygen species (ROS) generation and mitochondrial biogenesis. Mitochondrial fragmentation precedes mitochondrial ROS generation and mitochondrial biogenesis, and may contribute to mitochondrial ROS overproduction and subsequent mitochondrial biogenesis. Fragmentation of mitochondria also facilitated the release of cytotoxic mitochondrial proteins, such as Smac, from the mitochondria and subsequent activation of caspases. However, cell death induced by palmitate and cAMP was caspase-independent and mainly necrotic.
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Sabaretnam T, Harris MJ, Kockx M, Witting PK, Le Couteur DG, Kritharides L. Effects of hydrogen peroxide and apolipoprotein E isoforms on apolipoprotein E trafficking in HepG2 cells. Clin Exp Pharmacol Physiol 2009; 36:e96-102. [PMID: 19793104 DOI: 10.1111/j.1440-1681.2009.05306.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
1. The major source of apolipoprotein E (apoE) is the liver. In the present study, the effects of oxidative stress and apoE isoforms on apoE distribution and trafficking were established using the HepG2 liver tumour cell line. 2. Hydrogen peroxide (0, 25, 250 and 1000 micromol/L) was associated with rapid and concentration-dependent redistribution of apoE into the early endosomal compartment. This redistribution was achieved with a much lower concentration (25 micromol/L) than that needed to induce changes in intracellular apoE mRNA expression, apoE protein levels and markers of oxidative stress (250-1000 micromol/L). 3. Live cell imaging of apoE3-green fluorescent protein revealed a significant decrease in traffic velocity in response to oxidative stress. 4. The E4 isoform was associated with reduced trafficking velocity compared with the E3 isoform under basal conditions. 5. The results indicate that oxidative stress and apoE isoforms influence apoE trafficking and distribution within HepG2 cells. Altered apoE hepatocyte trafficking may provide a mechanistic link between oxidative stress, ageing and some diseases in older people.
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Brennan KM, Terry EN, Michal JJ, Kincaid RL, Johnson KA. Body weight loss in beef cows: II. Increased antioxidant messenger ribonucleic acid levels in skeletal muscle but not erythrocyte antioxidant activity. J Anim Sci 2009; 87:2867-73. [DOI: 10.2527/jas.2008-1301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Kim BY, Cui ZG, Lee SR, Kim SJ, Kang HK, Lee YK, Park DB. Effects of Asparagus officinalis Extracts on Liver Cell Toxicity and Ethanol Metabolism. J Food Sci 2009; 74:H204-8. [DOI: 10.1111/j.1750-3841.2009.01263.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Yang X, Zhou Y, Jin R, Chan C. Reconstruct modular phenotype-specific gene networks by knowledge-driven matrix factorization. ACTA ACUST UNITED AC 2009; 25:2236-43. [PMID: 19542155 DOI: 10.1093/bioinformatics/btp376] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
MOTIVATION Reconstructing gene networks from microarray data has provided mechanistic information on cellular processes. A popular structure learning method, Bayesian network inference, has been used to determine network topology despite its shortcomings, i.e. the high-computational cost when analyzing a large number of genes and the inefficiency in exploiting prior knowledge, such as the co-regulation information of the genes. To address these limitations, we are introducing an alternative method, knowledge-driven matrix factorization (KMF) framework, to reconstruct phenotype-specific modular gene networks. RESULTS Considering the reconstruction of gene network as a matrix factorization problem, we first use the gene expression data to estimate a correlation matrix, and then factorize the correlation matrix to recover the gene modules and the interactions between them. Prior knowledge from Gene Ontology is integrated into the matrix factorization. We applied this KMF algorithm to hepatocellular carcinoma (HepG2) cells treated with free fatty acids (FFAs). By comparing the module networks for the different conditions, we identified the specific modules that are involved in conferring the cytotoxic phenotype induced by palmitate. Further analysis of the gene modules of the different conditions suggested individual genes that play important roles in palmitate-induced cytotoxicity. In summary, KMF can efficiently integrate gene expression data with prior knowledge, thereby providing a powerful method of reconstructing phenotype-specific gene networks and valuable insights into the mechanisms that govern the phenotype.
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Affiliation(s)
- Xuerui Yang
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA
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Yang X, Chan C. Repression of PKR mediates palmitate-induced apoptosis in HepG2 cells through regulation of Bcl-2. Cell Res 2009; 19:469-86. [PMID: 19259124 PMCID: PMC2664847 DOI: 10.1038/cr.2009.25] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
In the present study we found that double-stranded RNA-dependent protein kinase (PKR) regulates the protein expression level and the phosphorylation of Bcl-2 and exploits an anti-apoptotic role in human hepatocellular carcinoma cells (HepG2). Saturated free fatty acids (FFAs), e.g. palmitate, have been shown to induce cellular apoptosis in various types of cells by different mechanisms. We found palmitate down-regulates the activity of PKR, and thereby decreases the protein level of Bcl-2, mediated, in part, by the NF-κB transcription factor. In addition to the protein level of Bcl-2, the phosphorylation of Bcl-2 at different amino acid residues, such as Ser70 and Ser87, is also important in regulating cellular apoptosis. The decrease in the phosphorylation of Bcl-2 at Ser70 upon exposure to palmitate is mediated by PKR and possibly JNK, while the phosphorylation of Bcl-2 at Ser87 is not affected by palmitate or PKR. In summary, PKR mediates the regulation of the protein level and the phosphorylation status of Bcl-2, providing a novel mechanism of palmitate-induced apoptosis in HepG2 cells.
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Affiliation(s)
- Xuerui Yang
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA
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Leekumjorn S, Cho HJ, Wu Y, Wright NT, Sum AK, Chan C. The role of fatty acid unsaturation in minimizing biophysical changes on the structure and local effects of bilayer membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1508-16. [PMID: 19371719 DOI: 10.1016/j.bbamem.2009.04.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Revised: 04/06/2009] [Accepted: 04/06/2009] [Indexed: 11/18/2022]
Abstract
Studying the effects of saturated and unsaturated fatty acids on biological and model (liposomes) membranes could provide insight into the contribution of biophysical effects on the cytotoxicity observed with saturated fatty acids. In vitro experiments suggest that unsaturated fatty acids, such as oleate and linoleate, are less toxic, and have less impact on the membrane fluidity. To understand and assess the biophysical changes in the presence of the different fatty acids, we performed computational analyses of model liposomes with palmitate, oleate, and linoleate. The computational results indicate that the unsaturated fatty acid chain serves as a membrane stabilizer by preventing changes to the membrane fluidity. Based on a Voronoi tessellation analysis, unsaturated fatty acids have structural properties that can reduce the lipid ordering within the model membranes. In addition, hydrogen bond analysis indicates a more uniform level of membrane hydration in the presence of oleate and linoleate as compared to palmitate. Altogether, these observations from the computational studies provide a possible mechanism by which unsaturated fatty acids minimize biophysical changes and protect the cellular membrane and structure. To corroborate our findings, we also performed a liposomal leakage study to assess how the different fatty acids alter the membrane integrity of liposomes. This showed that palmitate, a saturated fatty acid, caused greater destabilization of liposomes (more "leaky") than oleate, an unsaturated fatty acid.
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Affiliation(s)
- Sukit Leekumjorn
- Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
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Abstract
Drug-induced liver toxicity is one of the leading causes of acute liver failure in the United States, exceeding all other causes combined. The objective of this paper is to describe systems biology methods for identifying pathways involved in liver toxicity induced by free fatty acids (FFA) and tumor necrosis factor (TNF)-α in human hepatoblastoma cells (HepG2/C3A). Systems biology approaches were developed to integrate multi-level data, i.e., gene expression, metabolite profile, toxicity measurements and a priori knowledge to identify gene targets for modulating liver toxicity. Targets that modulate liver toxicity, in vitro, were computationally predicted and some targets were experimentally validated.
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Affiliation(s)
- Zheng Li
- Cellular and Molecular Biology Lab, Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA.
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Anderson N, Borlak J. Molecular Mechanisms and Therapeutic Targets in Steatosis and Steatohepatitis. Pharmacol Rev 2008; 60:311-57. [DOI: 10.1124/pr.108.00001] [Citation(s) in RCA: 291] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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47
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Lambertucci RH, Hirabara SM, Silveira LDR, Levada-Pires AC, Curi R, Pithon-Curi TC. Palmitate increases superoxide production through mitochondrial electron transport chain and NADPH oxidase activity in skeletal muscle cells. J Cell Physiol 2008; 216:796-804. [PMID: 18446788 DOI: 10.1002/jcp.21463] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effect of unbound palmitic acid (PA) at plasma physiological concentration range on reactive oxygen species (ROS) production by cultured rat skeletal muscle cells was investigated. The participation of the main sites of ROS production was also examined. Production of ROS was evaluated by cytochrome c reduction and dihydroethidium oxidation assays. PA increased ROS production after 1 h incubation. A xanthine oxidase inhibitor did not change PA-induced ROS production. However, the treatment with a mitochondrial uncoupler and mitochondrial complex III inhibitor decreased superoxide production induced by PA. The importance of mitochondria was also evaluated in 1 h incubated rat soleus and extensor digitorum longus (EDL) muscles. Soleus muscle, which has a greater number of mitochondria than EDL, showed a higher superoxide production induced by PA. These results indicate that mitochondrial electron transport chain is an important contributor for superoxide formation induced by PA in skeletal muscle. Results obtained with etomoxir and bromopalmitate treatment indicate that PA has to be oxidized to raise ROS production. A partial inhibition of superoxide formation induced by PA was observed by treatment with diphenylene iodonium, an inhibitor of NADPH oxidase. The participation of this enzyme complex was confirmed through an increase of p47(phox) phosphorylation after treatment with PA.
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Affiliation(s)
- Rafael Herling Lambertucci
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
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Schönfeld P, Wojtczak L. Fatty acids as modulators of the cellular production of reactive oxygen species. Free Radic Biol Med 2008; 45:231-41. [PMID: 18482593 DOI: 10.1016/j.freeradbiomed.2008.04.029] [Citation(s) in RCA: 308] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 04/16/2008] [Accepted: 04/22/2008] [Indexed: 12/17/2022]
Abstract
Long-chain nonesterified ("free") fatty acids (FFA) and some of their derivatives and metabolites can modify intracellular production of reactive oxygen species (ROS), in particular O(2)(-) and H(2)O(2). In mitochondria, FFA exert a dual effect on ROS production. Because of slowing down the rate of electron flow through Complexes I and III of the respiratory chain due to interaction within the complex subunit structure, and between Complexes III and IV due to release of cytochrome c from the inner membrane, FFA increase the rate of ROS generation in the forward mode of electron transport. On the other hand, due to their protonophoric action on the inner mitochondrial membrane ("mild uncoupling effect"), FFA strongly decrease ROS generation in the reverse mode of electron transport. In the plasma membrane of phagocytic neutrophils and a number of other types of cells, polyunsaturated FFA stimulate O(2)(-) generation by NADPH oxidase. These effects of FFA can modulate signaling functions of ROS and be, at least partly, responsible for their proapoptotic effects in several types of cells.
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Affiliation(s)
- Peter Schönfeld
- Institute of Biochemistry and Cell Biology, Otto von Guericke University, Leipziger Str. 44, 39120 Magdeburg, Germany.
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Effects of reactive oxygen species on cellular wall disassembly of banana fruit during ripening. Food Chem 2008; 109:319-24. [DOI: 10.1016/j.foodchem.2007.12.041] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2007] [Revised: 12/08/2007] [Accepted: 12/17/2007] [Indexed: 02/07/2023]
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50
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Buratta M, Castigli E, Sciaccaluga M, Pellegrino RM, Spinozzi F, Roberti R, Corazzi L. Loss of cardiolipin in palmitate-treated GL15 glioblastoma cells favors cytochrome c release from mitochondria leading to apoptosis. J Neurochem 2008; 105:1019-31. [DOI: 10.1111/j.1471-4159.2007.05209.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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