101
|
Williams LM, Lago BA, McArthur AG, Raphenya AR, Pray N, Saleem N, Salas S, Paulson K, Mangar RS, Liu Y, Vo AH, Shavit JA. The transcription factor, Nuclear factor, erythroid 2 (Nfe2), is a regulator of the oxidative stress response during Danio rerio development. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2016; 180:141-154. [PMID: 27716579 PMCID: PMC5274700 DOI: 10.1016/j.aquatox.2016.09.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/28/2016] [Accepted: 09/30/2016] [Indexed: 05/17/2023]
Abstract
Development is a complex and well-defined process characterized by rapid cell proliferation and apoptosis. At this stage in life, a developmentally young organism is more sensitive to toxicants as compared to an adult. In response to pro-oxidant exposure, members of the Cap'n'Collar (CNC) basic leucine zipper (b-ZIP) transcription factor family (including Nfe2 and Nfe2-related factors, Nrfs) activate the expression of genes whose protein products contribute to reduced toxicity. Here, we studied the role of the CNC protein, Nfe2, in the developmental response to pro-oxidant exposure in the zebrafish (Danio rerio). Following acute waterborne exposures to diquat or tert-buytlhydroperoxide (tBOOH) at one of three developmental stages, wildtype (WT) and nfe2 knockout (KO) embryos and larvae were morphologically scored and their transcriptomes sequenced. Early in development, KO animals suffered from hypochromia that was made more severe through exposure to pro-oxidants; this phenotype in the KO may be linked to decreased expression of alas2, a gene involved in heme synthesis. WT and KO eleutheroembryos and larvae were phenotypically equally affected by exposure to pro-oxidants, where tBOOH caused more pronounced phenotypes as compared to diquat. Comparing diquat and tBOOH exposed embryos relative to the WT untreated control, a greater number of genes were up-regulated in the tBOOH condition as compared to diquat (tBOOH: 304 vs diquat: 148), including those commonly found to be differentially regulated in the vertebrate oxidative stress response (OSR) (e.g. hsp70.2, txn1, and gsr). When comparing WT and KO across all treatments and times, there were 1170 genes that were differentially expressed, of which 33 are known targets of the Nrf proteins Nrf1 and Nrf2. More specifically, in animals exposed to pro-oxidants a total of 968 genes were differentially expressed between WT and KO across developmental time, representing pathways involved in coagulation, embryonic organ development, body fluid level regulation, erythrocyte differentiation, and oxidation-reduction, amongst others. The greatest number of genes that changed in expression between WT and KO occurred in animals exposed to diquat at 2h post fertilization (hpf). Across time and treatment, there were six genes (dhx40, cfap70, dnajb9b, slc35f4, spi-c, and gpr19) that were significantly up-regulated in KO compared to WT and four genes (fhad1, cyp4v7, nlrp12, and slc16a6a) that were significantly down-regulated. None of these genes have been previously identified as targets of Nfe2 or the Nrf family. These results demonstrate that the zebrafish Nfe2 may be a regulator of both primitive erythropoiesis and the OSR during development.
Collapse
Affiliation(s)
- Larissa M Williams
- Biology Department, Bates College, 44 Campus Avenue, Lewiston, ME 04240, USA; The MDI Biological Laboratory, 159 Old Bar Harbor Road, Bar Harbor, ME 04609 USA, USA.
| | - Briony A Lago
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada.
| | - Andrew G McArthur
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada.
| | - Amogelang R Raphenya
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada.
| | - Nicholas Pray
- Biology Department, Bates College, 44 Campus Avenue, Lewiston, ME 04240, USA.
| | - Nabil Saleem
- Biology Department, Bates College, 44 Campus Avenue, Lewiston, ME 04240, USA; The MDI Biological Laboratory, 159 Old Bar Harbor Road, Bar Harbor, ME 04609 USA, USA.
| | - Sophia Salas
- Biology Department, Bates College, 44 Campus Avenue, Lewiston, ME 04240, USA; The MDI Biological Laboratory, 159 Old Bar Harbor Road, Bar Harbor, ME 04609 USA, USA.
| | - Katherine Paulson
- Biology Department, Bates College, 44 Campus Avenue, Lewiston, ME 04240, USA; The MDI Biological Laboratory, 159 Old Bar Harbor Road, Bar Harbor, ME 04609 USA, USA.
| | - Roshni S Mangar
- The MDI Biological Laboratory, 159 Old Bar Harbor Road, Bar Harbor, ME 04609 USA, USA; College of the Atlantic, 105 Eden Street, Bar Harbor, ME 04609, USA.
| | - Yang Liu
- Department of Pediatrics and Communicable Diseases, University of Michigan, 8200 MSRB III 1150 West Medical Center Drive, Ann Arbor, MI 48109, USA.
| | - Andy H Vo
- Department of Pediatrics and Communicable Diseases, University of Michigan, 8200 MSRB III 1150 West Medical Center Drive, Ann Arbor, MI 48109, USA.
| | - Jordan A Shavit
- Department of Pediatrics and Communicable Diseases, University of Michigan, 8200 MSRB III 1150 West Medical Center Drive, Ann Arbor, MI 48109, USA.
| |
Collapse
|
102
|
Katsuoka F, Yamazaki H, Yamamoto M. Small Maf deficiency recapitulates the liver phenotypes of Nrf1- and Nrf2-deficient mice. Genes Cells 2016; 21:1309-1319. [PMID: 27723178 DOI: 10.1111/gtc.12445] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/15/2016] [Indexed: 12/29/2022]
Abstract
Nrf1 and Nrf2 (NF-E2-related factors 1 and 2, respectively) are transcription factors that belong to the Cap'n'collar (CNC) family and play critical roles in various tissues, including the liver. Liver-specific Nrf1 knockout mice show hepatic steatosis, accompanied by dysregulation of various metabolic genes. Nrf2 knockout mice show impairment in the induction of antioxidant and xenobiotic-metabolizing enzyme genes. Although it has been shown that small Maf (sMaf) proteins act as obligatory partners of CNC proteins, their precise contributions to the function of CNC proteins remain unclear especially in the context of adult liver functions. To address this issue, we generated mice that conditionally lack expression of all sMaf proteins in the liver. The liver-specific sMaf-deficient mice develop hepatic steatosis and dysregulation of genes involved in lipid and amino acid metabolism and proteasomal subunit expression. Importantly, the gene expression profiles in the sMaf-deficient livers share a strong similarity with those in Nrf1-deficient livers. In addition, the basal expression levels of a number of Nrf2 target genes were diminished in the sMaf-deficient livers. These results provide the first genetic evidence that sMaf proteins are indispensable for liver functions as heterodimeric partners for Nrf1 and Nrf2.
Collapse
Affiliation(s)
- Fumiki Katsuoka
- Department of Integrative Genomics, Tohoku Medical Megabank Organization, Tohoku University, Sendai, 980-8573, Japan
| | - Hiromi Yamazaki
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, Sendai, 980-8575, Japan
| | - Masayuki Yamamoto
- Department of Integrative Genomics, Tohoku Medical Megabank Organization, Tohoku University, Sendai, 980-8573, Japan.,Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, Sendai, 980-8575, Japan
| |
Collapse
|
103
|
Molecular and cellular basis for the unique functioning of Nrf1, an indispensable transcription factor for maintaining cell homoeostasis and organ integrity. Biochem J 2016; 473:961-1000. [PMID: 27060105 DOI: 10.1042/bj20151182] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 01/26/2016] [Indexed: 12/30/2022]
Abstract
The consensuscis-regulatory AP-1 (activator protein-1)-like AREs (antioxidant-response elements) and/or EpREs (electrophile-response elements) allow for differential recruitment of Nrf1 [NF-E2 (nuclear factor-erythroid 2)-related factor 1], Nrf2 and Nrf3, together with each of their heterodimeric partners (e.g. sMaf, c-Jun, JunD or c-Fos), to regulate different sets of cognate genes. Among them, NF-E2 p45 and Nrf3 are subject to tissue-specific expression in haemopoietic and placental cell lineages respectively. By contrast, Nrf1 and Nrf2 are two important transcription factors expressed ubiquitously in various vertebrate tissues and hence may elicit putative combinational or competitive functions. Nevertheless, they have de facto distinct biological activities because knockout of their genes in mice leads to distinguishable phenotypes. Of note, Nrf2 is dispensable during development and growth, albeit it is accepted as a master regulator of antioxidant, detoxification and cytoprotective genes against cellular stress. Relative to the water-soluble Nrf2, less attention has hitherto been drawn to the membrane-bound Nrf1, even though it has been shown to be indispensable for embryonic development and organ integrity. The biological discrepancy between Nrf1 and Nrf2 is determined by differences in both their primary structures and topovectorial subcellular locations, in which they are subjected to distinct post-translational processing so as to mediate differential expression of ARE-driven cytoprotective genes. In the present review, we focus on the molecular and cellular basis for Nrf1 and its isoforms, which together exert its essential functions for maintaining cellular homoeostasis, normal organ development and growth during life processes. Conversely, dysfunction of Nrf1 results in spontaneous development of non-alcoholic steatohepatitis, hepatoma, diabetes and neurodegenerative diseases in animal models.
Collapse
|
104
|
Taniguchi K, Yamachika S, He F, Karin M. p62/SQSTM1-Dr. Jekyll and Mr. Hyde that prevents oxidative stress but promotes liver cancer. FEBS Lett 2016; 590:2375-97. [PMID: 27404485 DOI: 10.1002/1873-3468.12301] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 07/08/2016] [Accepted: 07/09/2016] [Indexed: 12/17/2022]
Abstract
p62/SQSTM1 is a multifunctional signaling hub and autophagy adaptor with many binding partners, which allow it to activate mTORC1-dependent nutrient sensing, NF-κB-mediated inflammatory responses, and the NRF2-activated antioxidant defense. p62 recognizes polyubiquitin chains via its C-terminal domain and binds to LC3 via its LIR motif, thereby promoting the autophagic degradation of ubiquitinated cargos. p62 accumulates in many human liver diseases, including nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC), where it is a component of Mallory-Denk bodies and intracellular hyaline bodies. Chronic p62 elevation contributes to HCC development by preventing oncogene-induced senescence and death of cancer-initiating cells and enhancing their proliferation. In this review, we discuss p62-mediated signaling pathways and their roles in liver pathophysiology, especially NASH and HCC.
Collapse
Affiliation(s)
- Koji Taniguchi
- Laboratory of Gene Regulation and Signal Transduction, Departments of Pharmacology and Pathology, University of California San Diego, La Jolla, CA, USA.,Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.,Department of Microbiology and Immunology, Keio University School of Medicine, Tokyo, Japan
| | - Shinichiro Yamachika
- Laboratory of Gene Regulation and Signal Transduction, Departments of Pharmacology and Pathology, University of California San Diego, La Jolla, CA, USA
| | - Feng He
- Laboratory of Gene Regulation and Signal Transduction, Departments of Pharmacology and Pathology, University of California San Diego, La Jolla, CA, USA
| | - Michael Karin
- Laboratory of Gene Regulation and Signal Transduction, Departments of Pharmacology and Pathology, University of California San Diego, La Jolla, CA, USA
| |
Collapse
|
105
|
Kang JW, Hong JM, Lee SM. Melatonin enhances mitophagy and mitochondrial biogenesis in rats with carbon tetrachloride-induced liver fibrosis. J Pineal Res 2016; 60:383-93. [PMID: 26882442 DOI: 10.1111/jpi.12319] [Citation(s) in RCA: 168] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 02/09/2016] [Indexed: 12/14/2022]
Abstract
Liver fibrosis leads to liver cirrhosis and failure, and no effective treatment is currently available. Growing evidence supports a link between mitochondrial dysfunction and liver fibrogenesis and mitochondrial quality control-based therapy has emerged as a new therapeutic target. We investigated the protective mechanisms of melatonin against mitochondrial dysfunction-involved liver fibrosis, focusing on mitophagy and mitochondrial biogenesis. Rats were treated with carbon tetrachloride (CCl4) dissolved in olive oil (0.5 mL/kg, twice a week, i.p.) for 8 wk. Melatonin was administered orally at 2.5, 5, and 10 mg/kg once a day. Chronic CCl4 exposure induced collagen deposition, hepatocellular damage, and oxidative stress, and melatonin attenuated these increases. Increases in mRNA and protein expression levels of transforming growth factor β1 and α-smooth muscle actin in response to CCl4 were attenuated by melatonin. Melatonin attenuated hallmarks of mitochondrial dysfunction, such as mitochondrial swelling and glutamate dehydrogenase release. Chronic CCl4 exposure impaired mitophagy and mitochondrial biogenesis, and melatonin attenuated this impairment, as indicated by increases in mitochondrial DNA and in protein levels of PTEN-induced putative kinase 1 (PINK1); Parkin; peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α); nuclear respiratory factor 1 (NRF1); and transcription factor A, mitochondrial (TFAM). CCl4-mediated decreases in mitochondrial fission- and fusion-related proteins, such as dynamin-related protein 1 (DRP1) and mitofusin 2, were also attenuated by melatonin. Moreover, melatonin induced AMP-activated protein kinase (AMPK) phosphorylation. These results suggest that melatonin protects against liver fibrosis via upregulation of mitophagy and mitochondrial biogenesis, and may be useful as an anti-fibrotic treatment.
Collapse
Affiliation(s)
- Jung-Woo Kang
- School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi-do, Korea
| | - Jeong-Min Hong
- School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi-do, Korea
| | - Sun-Mee Lee
- School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi-do, Korea
| |
Collapse
|
106
|
TALENs-directed knockout of the full-length transcription factor Nrf1α that represses malignant behaviour of human hepatocellular carcinoma (HepG2) cells. Sci Rep 2016; 6:23775. [PMID: 27065079 PMCID: PMC4827396 DOI: 10.1038/srep23775] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 03/14/2016] [Indexed: 02/07/2023] Open
Abstract
The full-length Nrf1α is processed into distinct isoforms, which together regulate genes essential for maintaining cellular homeostasis and organ integrity, and liver-specific loss of Nrf1 in mice results in spontaneous hepatoma. Herein, we report that the human constitutive Nrf1α, rather than smaller Nrf1β/γ, expression is attenuated or abolished in the case of low-differentiated high-metastatic hepatocellular carcinomas. Therefore, Nrf1α is of importance in the physio-pathological origin and development, but its specific pathobiological function(s) remains elusive. To address this, TALENs-directed knockout of Nrf1α, but not Nrf1β/γ, is created in the human hepatocellular carcinoma (HepG2) cells. The resulting Nrf1α−/− cells are elongated, with slender spindle-shapes and enlarged gaps between cells observed under scanning electron microscope. When compared with wild-type controls, the invasive and migratory abilities of Nrf1α−/− cells are increased significantly, along with the cell-cycle G2-M arrest and S-phase reduction, as accompanied by suppressed apoptosis. Despite a modest increase in the soft-agar colony formation of Nrf1α−/− cells, its loss-of-function markedly promotes malgrowth of the subcutaneous carcinoma xenograft in nude mice with hepatic metastasis. Together with molecular expression results, we thus suppose requirement of Nrf1α (and major derivates) for gene regulatory mechanisms repressing cancer cell process (e.g. EMT) and malignant behaviour (e.g. migration).
Collapse
|
107
|
Small Maf proteins (MafF, MafG, MafK): History, structure and function. Gene 2016; 586:197-205. [PMID: 27058431 DOI: 10.1016/j.gene.2016.03.058] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 03/11/2016] [Accepted: 03/30/2016] [Indexed: 12/12/2022]
Abstract
The small Maf proteins (sMafs) are basic region leucine zipper (bZIP)-type transcription factors. The basic region of the Maf family is unique among the bZIP factors, and it contributes to the distinct DNA-binding mode of this class of proteins. MafF, MafG and MafK are the three vertebrate sMafs, and no functional differences have been observed among them in terms of their bZIP structures. sMafs form homodimers by themselves, and they form heterodimers with cap 'n' collar (CNC) proteins (p45 NF-E2, Nrf1, Nrf2, and Nrf3) and also with Bach proteins (Bach1 and Bach2). Because CNC and Bach proteins cannot bind to DNA as monomers, sMafs are indispensable partners that are required by CNC and Bach proteins to exert their functions. sMafs lack the transcriptional activation domain; hence, their homodimers act as transcriptional repressors. In contrast, sMafs participate in transcriptional activation or repression depending on their heterodimeric partner molecules and context. Mouse genetic analyses have revealed that various biological pathways are under the regulation of CNC-sMaf heterodimers. In this review, we summarize the history and current progress of sMaf studies in relation to their partners.
Collapse
|
108
|
Li DQ, Qiu M, Nie XM, Gui R, Huang MZ. Oxidored-nitro domain-containing protein 1 expression is associated with the progression of hepatocellular carcinoma. Oncol Lett 2016; 11:3003-3008. [PMID: 27123053 PMCID: PMC4840759 DOI: 10.3892/ol.2016.4362] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 03/04/2016] [Indexed: 12/13/2022] Open
Abstract
Hepatocarcinogenesis is a stepwise process during which multiple genes are altered. Understanding the molecular mechanisms that induce hepatocarcinogenesis may improve the screening, prevention and treatment of patients with hepatocellular carcinoma (HCC). In recent years, the oxidored-nitro domain-containing protein 1 (NOR1) gene has been identified to have an important role in the development of HCC in vitro experiments. The current study aimed to examine the expression of NOR1 mRNA and protein expression in specimens of normal liver, hepatitis, cirrhosis and HCC, together representing the process of HCC development. Furthermore, the association between NOR1 expression and clinicopathological parameters of HCC patients was analyzed. Tissue microarrays containing the specimens of human normal liver, hepatitis, cirrhosis and HCC were purchased, and in situ hybridization and immunohistochemistry were used to detect the expression of NOR1 mRNA and protein expression, respectively. It was revealed that the positive rate of NOR1 protein and mRNA expression in the specimens of hepatitis and cirrhosis were not significantly different from that in the normal liver samples. However, the specimens of HCC exhibited an increased positive rate of NOR1 protein and mRNA expression in comparison with the normal liver samples. In addition, a higher positive rate of NOR1 protein expression was observed in HCC patients with a poor pathological differentiation grade and high tumor node metastasis (TNM) stage. In conclusion, the present study provides evidence, for the first time, of the increased expression of NOR1 in human HCC tissues, and its correlation with the pathological stage and TNM status. These findings indicate that NOR1 may be involved in the progression of HCC and it could be employed as a predictive biomarker in HCC development.
Collapse
Affiliation(s)
- Deng-Qing Li
- Department of Laboratory Medicine, Xiangya Medical School, Central South University, Changsha, Hunan 410013, P.R. China
| | - Ming Qiu
- Department of Laboratory Medicine, Xiangya Medical School, Central South University, Changsha, Hunan 410013, P.R. China
| | - Xin-Min Nie
- Clinical Laboratory Centre of The Third Xiangya Hospital, Central South University, Changsha, Hunan 410013, P.R. China
| | - Rong Gui
- Clinical Laboratory Centre of The Third Xiangya Hospital, Central South University, Changsha, Hunan 410013, P.R. China
| | - Min-Zhu Huang
- Public Health School of Central South University, Changsha, Hunan 410078, P.R. China
| |
Collapse
|
109
|
Kim HM, Han JW, Chan JY. Nuclear Factor Erythroid-2 Like 1 (NFE2L1): Structure, function and regulation. Gene 2016; 584:17-25. [PMID: 26947393 DOI: 10.1016/j.gene.2016.03.002] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 02/18/2016] [Accepted: 03/01/2016] [Indexed: 02/06/2023]
Abstract
Nrf1 (also referred to as NFE2L1) is a member of the CNC-bZIP family of transcription factors that are characterized by a highly conserved CNC-domain, and a basic-leucine zipper domain required for dimerization and DNA binding. Nrf1 is ubiquitously expressed across tissue and cell types as various isoforms, and is induced by stress signals from a broad spectrum of stimuli. Evidence indicates that Nrf1 plays an important role in regulating a range of cellular functions including oxidative stress response, differentiation, inflammatory response, metabolism, and maintaining proteostasis. Thus, Nrf1 has been implicated in the pathogenesis of various disease processes including cancer development, and degenerative and metabolic disorders. This review summarizes our current understanding of Nrf1 and the molecular mechanism underlying its regulation and action in different cellular functions.
Collapse
Affiliation(s)
- Hyun Min Kim
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Sciences, Irvine, CA 92697, USA
| | - Jeong Woo Han
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Sciences, Irvine, CA 92697, USA
| | - Jefferson Y Chan
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Sciences, Irvine, CA 92697, USA.
| |
Collapse
|
110
|
Teng YC, Shen ZQ, Kao CH, Tsai TF. Hepatocellular carcinoma mouse models: Hepatitis B virus-associated hepatocarcinogenesis and haploinsufficient tumor suppressor genes. World J Gastroenterol 2016; 22:300-325. [PMID: 26755878 PMCID: PMC4698494 DOI: 10.3748/wjg.v22.i1.300] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 10/14/2015] [Accepted: 11/24/2015] [Indexed: 02/06/2023] Open
Abstract
The multifactorial and multistage pathogenesis of hepatocellular carcinoma (HCC) has fascinated a wide spectrum of scientists for decades. While a number of major risk factors have been identified, their mechanistic roles in hepatocarcinogenesis still need to be elucidated. Many tumor suppressor genes (TSGs) have been identified as being involved in HCC. These TSGs can be classified into two groups depending on the situation with respect to allelic mutation/loss in the tumors: the recessive TSGs with two required mutated alleles and the haploinsufficient TSGs with one required mutated allele. Hepatitis B virus (HBV) is one of the most important risk factors associated with HCC. Although mice cannot be infected with HBV due to the narrow host range of HBV and the lack of a proper receptor, one advantage of mouse models for HBV/HCC research is the numerous and powerful genetic tools that help investigate the phenotypic effects of viral proteins and allow the dissection of the dose-dependent action of TSGs. Here, we mainly focus on the application of mouse models in relation to HBV-associated HCC and on TSGs that act either in a recessive or in a haploinsufficient manner. Discoveries obtained using mouse models will have a great impact on HCC translational medicine.
Collapse
|
111
|
Cui T, Lai Y, Janicki JS, Wang X. Nuclear factor erythroid-2 related factor 2 (Nrf2)-mediated protein quality control in cardiomyocytes. Front Biosci (Landmark Ed) 2016; 21:192-202. [PMID: 26709769 DOI: 10.2741/4384] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Protein quality control (PQC) acts to minimize the level and toxicity of malfolded proteins in the cell. It is performed by an elaborate network of molecular chaperones and targeted protein degradation pathways. PQC monitors and maintains protein homeostasis or proteostasis in the cells. Whilst chaperones may actively promote refolding of malfolded proteins, the malfolded proteins which cannot be correctly refolded are degraded by the ubiquitin proteasome system (UPS) and the autophagic-lysosome pathway (ALP). The UPS degrades individual misfolded protein molecules, whereas the ALP removes large and less soluble protein aggregates and organelles. Emerging evidence indicates that dysregulated and inadequate PQC play an important role in the pathogenesis of not only classic conformational disease but more common forms of cardiac pathology such as cardiac pathological hypertrophy and heart failure. Nuclear factor erythroid 2-related factor 2 (Nrf2), a master transcription factor of cellular defense, appears to regulate the USP and the ALP by directly controlling the expression of UPS- and ALP- related genes. This article highlights an emerging role of Nrf2 in the regulation of intracellular PQC as well as its potential involvement in cardiac pathology.
Collapse
Affiliation(s)
| | | | - Jospeh S Janicki
- Department of Cell Biology and Anatomy, University of South Carolina School of Medicine, Columbia, SC, 29209, USA
| | - Xuejun Wang
- Division of Biomedical Sciences, University of South Dakota Sanford School of Medicine, Vermillion, South Dakota, USA.,
| |
Collapse
|
112
|
Satapati S, Kucejova B, Duarte JAG, Fletcher JA, Reynolds L, Sunny NE, He T, Nair LA, Livingston KA, Fu X, Merritt ME, Sherry AD, Malloy CR, Shelton JM, Lambert J, Parks EJ, Corbin I, Magnuson MA, Browning JD, Burgess SC. Mitochondrial metabolism mediates oxidative stress and inflammation in fatty liver. J Clin Invest 2015; 125:4447-62. [PMID: 26571396 DOI: 10.1172/jci82204] [Citation(s) in RCA: 283] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 10/08/2015] [Indexed: 02/06/2023] Open
Abstract
Mitochondria are critical for respiration in all tissues; however, in liver, these organelles also accommodate high-capacity anaplerotic/cataplerotic pathways that are essential to gluconeogenesis and other biosynthetic activities. During nonalcoholic fatty liver disease (NAFLD), mitochondria also produce ROS that damage hepatocytes, trigger inflammation, and contribute to insulin resistance. Here, we provide several lines of evidence indicating that induction of biosynthesis through hepatic anaplerotic/cataplerotic pathways is energetically backed by elevated oxidative metabolism and hence contributes to oxidative stress and inflammation during NAFLD. First, in murine livers, elevation of fatty acid delivery not only induced oxidative metabolism, but also amplified anaplerosis/cataplerosis and caused a proportional rise in oxidative stress and inflammation. Second, loss of anaplerosis/cataplerosis via genetic knockdown of phosphoenolpyruvate carboxykinase 1 (Pck1) prevented fatty acid-induced rise in oxidative flux, oxidative stress, and inflammation. Flux appeared to be regulated by redox state, energy charge, and metabolite concentration, which may also amplify antioxidant pathways. Third, preventing elevated oxidative metabolism with metformin also normalized hepatic anaplerosis/cataplerosis and reduced markers of inflammation. Finally, independent histological grades in human NAFLD biopsies were proportional to oxidative flux. Thus, hepatic oxidative stress and inflammation are associated with elevated oxidative metabolism during an obesogenic diet, and this link may be provoked by increased work through anabolic pathways.
Collapse
|
113
|
Tebay LE, Robertson H, Durant ST, Vitale SR, Penning TM, Dinkova-Kostova AT, Hayes JD. Mechanisms of activation of the transcription factor Nrf2 by redox stressors, nutrient cues, and energy status and the pathways through which it attenuates degenerative disease. Free Radic Biol Med 2015; 88:108-146. [PMID: 26122708 PMCID: PMC4659505 DOI: 10.1016/j.freeradbiomed.2015.06.021] [Citation(s) in RCA: 604] [Impact Index Per Article: 67.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 12/11/2022]
Abstract
UNLABELLED Nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) regulates the basal and stress-inducible expression of a battery of genes encoding key components of the glutathione-based and thioredoxin-based antioxidant systems, as well as aldo-keto reductase, glutathione S-transferase, and NAD(P)H quinone oxidoreductase-1 drug-metabolizing isoenzymes along with multidrug-resistance-associated efflux pumps. It therefore plays a pivotal role in both intrinsic resistance and cellular adaptation to reactive oxygen species (ROS) and xenobiotics. Activation of Nrf2 can, however, serve as a double-edged sword because some of the genes it induces may contribute to chemical carcinogenesis by promoting futile redox cycling of polycyclic aromatic hydrocarbon metabolites or confer resistance to chemotherapeutic drugs by increasing the expression of efflux pumps, suggesting its cytoprotective effects will vary in a context-specific fashion. In addition to cytoprotection, Nrf2 also controls genes involved in intermediary metabolism, positively regulating those involved in NADPH generation, purine biosynthesis, and the β-oxidation of fatty acids, while suppressing those involved in lipogenesis and gluconeogenesis. Nrf2 is subject to regulation at multiple levels. Its ability to orchestrate adaptation to oxidants and electrophiles is due principally to stress-stimulated modification of thiols within one of its repressors, the Kelch-like ECH-associated protein 1 (Keap1), which is present in the cullin-3 RING ubiquitin ligase (CRL) complex CRLKeap1. Thus modification of Cys residues in Keap1 blocks CRLKeap1 activity, allowing newly translated Nrf2 to accumulate rapidly and induce its target genes. The ability of Keap1 to repress Nrf2 can be attenuated by p62/sequestosome-1 in a mechanistic target of rapamycin complex 1 (mTORC1)-dependent manner, thereby allowing refeeding after fasting to increase Nrf2-target gene expression. In parallel with repression by Keap1, Nrf2 is also repressed by β-transducin repeat-containing protein (β-TrCP), present in the Skp1-cullin-1-F-box protein (SCF) ubiquitin ligase complex SCFβ-TrCP. The ability of SCFβ-TrCP to suppress Nrf2 activity is itself enhanced by prior phosphorylation of the transcription factor by glycogen synthase kinase-3 (GSK-3) through formation of a DSGIS-containing phosphodegron. However, formation of the phosphodegron in Nrf2 by GSK-3 is inhibited by stimuli that activate protein kinase B (PKB)/Akt. In particular, PKB/Akt activity can be increased by phosphoinositide 3-kinase and mTORC2, thereby providing an explanation of why antioxidant-responsive element-driven genes are induced by growth factors and nutrients. Thus Nrf2 activity is tightly controlled via CRLKeap1 and SCFβ-TrCP by oxidative stress and energy-based signals, allowing it to mediate adaptive responses that restore redox homeostasis and modulate intermediary metabolism. Based on the fact that Nrf2 influences multiple biochemical pathways in both positive and negative ways, it is likely its dose-response curve, in terms of susceptibility to certain degenerative disease, is U-shaped. Specifically, too little Nrf2 activity will lead to loss of cytoprotection, diminished antioxidant capacity, and lowered β-oxidation of fatty acids, while conversely also exhibiting heightened sensitivity to ROS-based signaling that involves receptor tyrosine kinases and apoptosis signal-regulating kinase-1. By contrast, too much Nrf2 activity disturbs the homeostatic balance in favor of reduction, and so may have deleterious consequences including overproduction of reduced glutathione and NADPH, the blunting of ROS-based signal transduction, epithelial cell hyperplasia, and failure of certain cell types to differentiate correctly. We discuss the basis of a putative U-shaped Nrf2 dose-response curve in terms of potentially competing processes relevant to different stages of tumorigenesis.
Collapse
Affiliation(s)
- Lauren E Tebay
- Jacqui Wood Cancer Centre, Division of Cancer Research, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK
| | - Holly Robertson
- Jacqui Wood Cancer Centre, Division of Cancer Research, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK
| | - Stephen T Durant
- AstraZeneca Oncology Innovative Medicines, Bioscience, 33F197 Mereside, Alderley Park, Cheshire SK10 4TG, UK
| | - Steven R Vitale
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6160, USA
| | - Trevor M Penning
- Center of Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6160, USA
| | - Albena T Dinkova-Kostova
- Jacqui Wood Cancer Centre, Division of Cancer Research, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK
| | - John D Hayes
- Jacqui Wood Cancer Centre, Division of Cancer Research, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK.
| |
Collapse
|
114
|
Blackwell TK, Steinbaugh MJ, Hourihan JM, Ewald CY, Isik M. SKN-1/Nrf, stress responses, and aging in Caenorhabditis elegans. Free Radic Biol Med 2015; 88:290-301. [PMID: 26232625 PMCID: PMC4809198 DOI: 10.1016/j.freeradbiomed.2015.06.008] [Citation(s) in RCA: 381] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 06/17/2015] [Accepted: 06/18/2015] [Indexed: 01/06/2023]
Abstract
The mammalian Nrf/CNC proteins (Nrf1, Nrf2, Nrf3, p45 NF-E2) perform a wide range of cellular protective and maintenance functions. The most thoroughly described of these proteins, Nrf2, is best known as a regulator of antioxidant and xenobiotic defense, but more recently has been implicated in additional functions that include proteostasis and metabolic regulation. In the nematode Caenorhabditis elegans, which offers many advantages for genetic analyses, the Nrf/CNC proteins are represented by their ortholog SKN-1. Although SKN-1 has diverged in aspects of how it binds DNA, it exhibits remarkable functional conservation with Nrf/CNC proteins in other species and regulates many of the same target gene families. C. elegans may therefore have considerable predictive value as a discovery model for understanding how mammalian Nrf/CNC proteins function and are regulated in vivo. Work in C. elegans indicates that SKN-1 regulation is surprisingly complex and is influenced by numerous growth, nutrient, and metabolic signals. SKN-1 is also involved in a wide range of homeostatic functions that extend well beyond the canonical Nrf2 function in responses to acute stress. Importantly, SKN-1 plays a central role in diverse genetic and pharmacologic interventions that promote C. elegans longevity, suggesting that mechanisms regulated by SKN-1 may be of conserved importance in aging. These C. elegans studies predict that mammalian Nrf/CNC protein functions and regulation may be similarly complex and that the proteins and processes that they regulate are likely to have a major influence on mammalian life- and healthspan.
Collapse
Affiliation(s)
- T Keith Blackwell
- Research Division, Joslin Diabetes Center, One Joslin Place, Boston, MA 02215, USA; Department of Genetics and Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02215, USA.
| | - Michael J Steinbaugh
- Research Division, Joslin Diabetes Center, One Joslin Place, Boston, MA 02215, USA; Department of Genetics and Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02215, USA
| | - John M Hourihan
- Research Division, Joslin Diabetes Center, One Joslin Place, Boston, MA 02215, USA; Department of Genetics and Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Collin Y Ewald
- Research Division, Joslin Diabetes Center, One Joslin Place, Boston, MA 02215, USA; Department of Genetics and Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Meltem Isik
- Research Division, Joslin Diabetes Center, One Joslin Place, Boston, MA 02215, USA; Department of Genetics and Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02215, USA
| |
Collapse
|
115
|
Steinbaugh MJ, Narasimhan SD, Robida-Stubbs S, Moronetti Mazzeo LE, Dreyfuss JM, Hourihan JM, Raghavan P, Operaña TN, Esmaillie R, Blackwell TK. Lipid-mediated regulation of SKN-1/Nrf in response to germ cell absence. eLife 2015. [PMID: 26196144 PMCID: PMC4541496 DOI: 10.7554/elife.07836] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In Caenorhabditis elegans, ablation of germline stem cells (GSCs) extends lifespan, but also increases fat accumulation and alters lipid metabolism, raising the intriguing question of how these effects might be related. Here, we show that a lack of GSCs results in a broad transcriptional reprogramming in which the conserved detoxification regulator SKN-1/Nrf increases stress resistance, proteasome activity, and longevity. SKN-1 also activates diverse lipid metabolism genes and reduces fat storage, thereby alleviating the increased fat accumulation caused by GSC absence. Surprisingly, SKN-1 is activated by signals from this fat, which appears to derive from unconsumed yolk that was produced for reproduction. We conclude that SKN-1 plays a direct role in maintaining lipid homeostasis in which it is activated by lipids. This SKN-1 function may explain the importance of mammalian Nrf proteins in fatty liver disease and suggest that particular endogenous or dietary lipids might promote health through SKN-1/Nrf.
Collapse
Affiliation(s)
| | | | | | | | | | - John M Hourihan
- Department of Genetics and Harvard Stem Cell Institute, Harvard Medical School, Boston, United States
| | | | | | - Reza Esmaillie
- Research Division, Joslin Diabetes Center, Boston, United States
| | | |
Collapse
|
116
|
Zhang Y, Li S, Xiang Y, Qiu L, Zhao H, Hayes JD. The selective post-translational processing of transcription factor Nrf1 yields distinct isoforms that dictate its ability to differentially regulate gene expression. Sci Rep 2015; 5:12983. [PMID: 26268886 PMCID: PMC4534795 DOI: 10.1038/srep12983] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 07/13/2015] [Indexed: 12/20/2022] Open
Abstract
Upon translation, the N-terminal homology box 1 (NHB1) signal anchor sequence of Nrf1 integrates it within the endoplasmic reticulum (ER) whilst its transactivation domains [TADs, including acidic domain 1 (AD1), the flanking Asn/Ser/Thr-rich (NST) domain and AD2] are transiently translocated into the ER lumen, whereupon the NST domain is glycosylated to yield an inactive 120-kDa glycoprotein. Subsequently, these TADs are retrotranslocated into extra-luminal subcellular compartments, where Nrf1 is deglycosylated to yield an active 95-kDa isoform. Herein, we report that AD1 and AD2 are required for the stability of the 120-kDa Nrf1 glycoprotein, but not that of the non-glycosylated/de-glycosylated 95-kDa isoform. Degrons within AD1 do not promote proteolytic degradation of the 120-kDa Nrf1 glycoprotein. However, repositioning of AD2-adjoining degrons (i.e. DSGLS-containing SDS1 and PEST2 sequences) into the cyto/nucleoplasm enables selective topovectorial processing of Nrf1 by the proteasome and/or calpains to generate a cleaved active 85-kDa Nrf1 or a dominant-negative 36-kDa Nrf1γ. Production of Nrf1γ is abolished by removal of SDS1 or PEST2 degrons, whereas production of the cleaved 85-kDa Nrf1 is blocked by deletion of the ER luminal-anchoring NHB2 sequence (aa 81–106). Importantly, Nrf1 activity is positively and/or negatively regulated by distinct doses of proteasome and calpain inhibitors.
Collapse
Affiliation(s)
- Yiguo Zhang
- 1] The NSFC-funded Laboratory of Cell Biochemistry and Gene Regulation, College of Medical Bioengineering and Faculty of Life Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 400044, China [2] Jacqui Wood Cancer Centre, James Arrott Drive, Division of Cancer Research, Medical Research Institute, Ninewells Hospital &Medical School, University of Dundee, DD1 9SY, Scotland, UK
| | - Shaojun Li
- The NSFC-funded Laboratory of Cell Biochemistry and Gene Regulation, College of Medical Bioengineering and Faculty of Life Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 400044, China
| | - Yuancai Xiang
- The NSFC-funded Laboratory of Cell Biochemistry and Gene Regulation, College of Medical Bioengineering and Faculty of Life Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 400044, China
| | - Lu Qiu
- The NSFC-funded Laboratory of Cell Biochemistry and Gene Regulation, College of Medical Bioengineering and Faculty of Life Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 400044, China
| | - Huakan Zhao
- The NSFC-funded Laboratory of Cell Biochemistry and Gene Regulation, College of Medical Bioengineering and Faculty of Life Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 400044, China
| | - John D Hayes
- Jacqui Wood Cancer Centre, James Arrott Drive, Division of Cancer Research, Medical Research Institute, Ninewells Hospital &Medical School, University of Dundee, DD1 9SY, Scotland, UK
| |
Collapse
|
117
|
Changing gears in Nrf1 research, from mechanisms of regulation to its role in disease and prevention. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:1260-76. [PMID: 26254094 DOI: 10.1016/j.bbagrm.2015.08.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 07/02/2015] [Accepted: 08/03/2015] [Indexed: 12/12/2022]
Abstract
The "cap'n'collar" bZIP transcription factor Nrf1 heterodimerizes with small Maf proteins to bind to the Antioxidant Response Element/Electrophile Response Element to transactivate antioxidant enzyme, phase 2 detoxification enzyme and proteasome subunit gene expression. Nrf1 specifically regulates pathways in lipid metabolism, amino acid metabolism, proteasomal degradation, the citric acid cycle, and the mitochondrial respiratory chain. Nrf1 is maintained in the endoplasmic reticulum (ER) in an inactive glycosylated state. Activation involves retrotranslocation from the ER lumen to the cytoplasm, deglycosylation and partial proteolytic processing to generate the active forms of Nrf1. Recent evidence has revealed how this factor is regulated and its involvement in various metabolic diseases. This review outlines Nrf1 structure, function, regulation and its links to insulin resistance, diabetes and inflammation. The glycosylation/deglycosylation of Nrf1 is controlled by glucose levels. Nrf1 glycosylation affects its control of glucose transport, glycolysis, gluconeogenesis and lipid metabolism.
Collapse
|
118
|
Transcription factor Nrf1 is negatively regulated by its O-GlcNAcylation status. FEBS Lett 2015; 589:2347-58. [PMID: 26231763 DOI: 10.1016/j.febslet.2015.07.030] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Revised: 07/19/2015] [Accepted: 07/20/2015] [Indexed: 12/30/2022]
Abstract
O-Linked N-acetylglucosamine transferase (OGT) was identified as an Nrf1-interacting protein. Herein, we show that Nrf1 enables interaction with OGT and their co-immunoprecipitates are O-GlcNAcylated by the enzyme. The putative O-GlcNAcylation negatively regulates Nrf1/TCF11 to reduce both its protein stability and transactivation activity of target gene expression. The turnover of Nrf1 is enhanced upon overexpression of OGT, which promotes ubiquitination of the CNC-bZIP protein. Furthermore, the serine/theorine-rich sequence of PEST2 degron within Nrf1 is identified to be involved in the protein O-GlcNAcylation by OGT. Overall, Nrf1 is negatively regulated by its O-GlcNAcylation status that depends on the glucose concentrations.
Collapse
|
119
|
Nyagode BA, Williams IR, Morgan ET. Altered inflammatory responses to Citrobacter rodentium infection, but not bacterial lipopolysaccharide, in mice lacking the Cyp4a10 or Cyp4a14 genes. Inflammation 2015; 37:893-907. [PMID: 24413902 DOI: 10.1007/s10753-013-9809-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Murine hepatic Cyp4a mRNAs are markedly downregulated during inflammation. Here, we investigated the roles of Cyp4a10 and Cyp4a14 in the response to infection with C. rodentium. Absence of either Cyp4a gene attenuated or abrogated the changes in spleen weight, colon crypt length, hepatic cytokine, and acute phase protein mRNAs, and serum acute phase proteins and cytokines caused by infection. Cyp4a10(-/-) mice on a low-salt diet had a similar hepatic acute phase response as those mice on a high-salt diet, suggesting that hypertension associated with this genotype is not the cause of their altered inflammatory response. In contrast, wild-type, Cyp4a10(-/-), and Cyp4a14(-/-) mice showed similar responses to injected LPS. These results implicate Cyp4a10 and Cyp4a14 in the regulation of the host inflammatory response to enteropathogenic bacterial infection but not to acute aseptic inflammation. Understanding the mechanism of this role may lead to novel therapeutic approaches in some inflammatory diseases.
Collapse
Affiliation(s)
- Beatrice A Nyagode
- Department of Pharmacology, Emory University School of Medicine, 5119 Rollins Research Center, 1510 Clifton Road, Atlanta, GA, 30322, USA
| | | | | |
Collapse
|
120
|
Karim MR, Taniguchi H, Kobayashi A. Constitutive activation of Drosophila CncC transcription factor reduces lipid formation in the fat body. Biochem Biophys Res Commun 2015; 463:693-8. [PMID: 26049108 DOI: 10.1016/j.bbrc.2015.05.126] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 05/31/2015] [Indexed: 12/21/2022]
Abstract
Accumulating evidence indicates that the vertebrate stress-response transcription factors Nrf1 and Nrf2 are involved in hepatic lipid metabolism. However, the underlying molecular mechanisms of Nrf1-and Nrf2-mediated lipid metabolism remain unclear. To elucidate the precise roles of Nrfs in this process, we analyzed the physiological role of CncC in lipid metabolism as a Drosophila model for vertebrate Nrf1 and Nrf2. We first examined whether CncC activity is repressed under physiological conditions through a species-conserved NHB1 (N-terminal homology box 1) domain, similar to that observed for Nrf1. Deletion of the NHB1 domain (CncCΔN) led to CncC-mediated rough-eye phenotypes and the induced expression of the CncC target gene gstD1 both in vivo and in vitro. Thus, we decided to explore how CncCΔN overexpression affects the formation of the fat body, which is the major lipid storage organ. Intriguingly, CncCΔN caused a significant reduction in lipid droplet size and triglyceride (TG) levels in the fat body compared to wild type. We found that CncCΔN induced a number of genes related to innate immunity that might have an effect on the regulation of cellular lipid storage. Our study provides new insights into the regulatory mechanism of CncC and its role in lipid homeostasis.
Collapse
Affiliation(s)
- M Rezaul Karim
- Laboratory for Genetic Code, Graduate School of Life and Medical Sciences, Doshisha University, Japan
| | - Hiroaki Taniguchi
- Laboratory for Genetic Code, Graduate School of Life and Medical Sciences, Doshisha University, Japan
| | - Akira Kobayashi
- Laboratory for Genetic Code, Graduate School of Life and Medical Sciences, Doshisha University, Japan.
| |
Collapse
|
121
|
Abstract
Defects in the maintenance of protein homeostasis, or proteostasis, has emerged as an underlying feature of a variety of human pathologies, including aging-related diseases. Proteostasis is achieved through the coordinated action of cellular systems overseeing amino acid availability, mRNA translation, protein folding, secretion, and degradation. The regulation of these distinct systems must be integrated at various points to attain a proper balance. In a recent study, we found that the mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) pathway, well known to enhance the protein synthesis capacity of cells while concordantly inhibiting autophagy, promotes the production of more proteasomes. Activation of mTORC1 genetically, through loss of the tuberous sclerosis complex (TSC) tumor suppressors, or physiologically, through growth factors or feeding, stimulates a transcriptional program involving the sterol-regulatory element binding protein 1 (SREBP1) and nuclear factor erythroid-derived 2-related factor 1 (NRF1; also known as NFE2L1) transcription factors leading to an increase in cellular proteasome content. As discussed here, our findings suggest that this increase in proteasome levels facilitates both the maintenance of proteostasis and the recovery of amino acids in the face of an increased protein load consequent to mTORC1 activation. We also consider the physiological and pathological implications of this unexpected new downstream branch of mTORC1 signaling.
Collapse
Affiliation(s)
- Yinan Zhang
- a Department of Genetics and Complex Diseases; Harvard T.H. Chan School of Public Health ; Boston , MA , USA
| | | |
Collapse
|
122
|
Tsujita T, Baird L, Furusawa Y, Katsuoka F, Hou Y, Gotoh S, Kawaguchi SI, Yamamoto M. Discovery of an NRF1-specific inducer from a large-scale chemical library using a direct NRF1-protein monitoring system. Genes Cells 2015; 20:563-77. [PMID: 25940588 DOI: 10.1111/gtc.12248] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Accepted: 03/26/2015] [Indexed: 11/26/2022]
Abstract
NRF1 (NF-E2-p45-related factor 1) plays an important role in the regulation of genes encoding proteasome subunits, a cystine transporter, and lipid-metabolizing enzymes. Global and tissue-specific disruptions of the Nrf1 gene in mice result in embryonic lethality and spontaneous development of severe tissue defects, respectively, suggesting NRF1 plays a critical role in vivo. Mechanistically, the continuous degradation of the NRF1 protein by the proteasome is regarded as a major regulatory nexus of NRF1 activity. To develop NRF1-specific inducers that act to overcome the phenotypes related to the lack of NRF1 activity, we constructed a novel NRF1ΔC-Luc fusion protein reporter and developed cell lines that stably express the reporter in Hepa1c1c7 cells for use in high-throughput screening. In screening of a chemical library with this reporter system, we identified two hit compounds that significantly induced luciferase activity. Through an examination of a series of derivatives of one of the hit compounds, we identified T1-20, which induced a 70-fold increase in luciferase activity. T1-20 significantly increased the level of NRF1 protein in the mouse liver, indicating that the compound is also functional in vivo. Thus, these results show the successful identification of the first small chemical compounds which specifically and significantly induce NRF1.
Collapse
Affiliation(s)
- Tadayuki Tsujita
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
- Department of Molecular Medicine and Therapy, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
| | - Liam Baird
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
| | - Yuki Furusawa
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
- Pharmaceutical Research Center, Mochida Pharmaceutical Co. Ltd, 722 Uenohara, Jimba, Gotemba, Shizuoka, 412-8524, Japan
| | - Fumiki Katsuoka
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
- Department of Bioscience for Drug Discovery, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
- Tohoku Medical Megabank Organization, Tohoku University, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
| | - Yoshika Hou
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
| | - Satomi Gotoh
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
| | - Shin-ichi Kawaguchi
- Department of Molecular Medicine and Therapy, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan
| | - Masayuki Yamamoto
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
- Department of Bioscience for Drug Discovery, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
- Tohoku Medical Megabank Organization, Tohoku University, 2-1 Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan
| |
Collapse
|
123
|
Noureddin M, Rinella ME. Nonalcoholic Fatty liver disease, diabetes, obesity, and hepatocellular carcinoma. Clin Liver Dis 2015; 19:361-79. [PMID: 25921668 PMCID: PMC6658171 DOI: 10.1016/j.cld.2015.01.012] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Diabetes and obesity are associated with nonalcoholic fatty liver disease (NAFLD) and an increased incidence of hepatocellular carcinoma (HCC). NAFLD is the commonest cause of chronic liver disease. HCC can develop in NAFLD patients even without cirrhosis, suggesting an association between the metabolic process and HCC and raising a concern that many cancers could be missed given high NAFLD prevalence and screening limitations. The increasing prevalence of these conditions and lack of effective treatments necessitate a better understanding of their connection. This article defines the known interrelationships and common pathways between NAFLD, diabetes, obesity and HCC and possible chemoprevention strategies.
Collapse
Affiliation(s)
- Mazen Noureddin
- Division of Gastrointestinal and Liver Diseases, USC Keck School of Medicine, 2011 Zonal Avenue, HMR 101, Los Angeles, CA 90033, USA
| | - Mary E. Rinella
- Division of Gastroenterology and Hepatology, Northwestern University Feinberg School of Medicine, 676 North Saint Clair, Arkes Pavillion 14-005, Chicago, IL 60611, USA,Corresponding author.
| |
Collapse
|
124
|
Streba LAM, Vere CC, Rogoveanu I, Streba CT. Nonalcoholic fatty liver disease, metabolic risk factors, and hepatocellular carcinoma: An open question. World J Gastroenterol 2015; 21:4103-4110. [PMID: 25892859 PMCID: PMC4394070 DOI: 10.3748/wjg.v21.i14.4103] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Revised: 01/17/2015] [Accepted: 02/13/2015] [Indexed: 02/06/2023] Open
Abstract
Non-alcoholic liver disease (NAFLD) defines liver abnormalities ranging from simple steatosis to nonalcoholic steatohepatitis with or without cirrhosis development, occurring in the absence of significant alcohol consumption, use of teratogenic medication, or hereditary disorders. The association between NAFLD and metabolic syndrome is well documented and widely recognized. Obesity, type 2 diabetes mellitus (T2DM), and dyslipidemia are the most common metabolic risk factors associated with NAFLD. Among the components of metabolic syndrome, current evidence strongly indicates obesity and diabetes as hepatocellular carcinoma (HCC) risk factors. There is also growing evidence that suggests an increased risk of HCC in NAFLD patients, even surpassing other etiologies in some high-income countries. Epidemiologic data demonstrate a parallel rise in prevalence of obesity, diabetes, NAFLD, and HCC. As obesity and its related diseases have steadily afflicted larger populations, HCC incidence is expected to increase in the future. Pathophysiologic mechanisms that underlie NAFLD development and subsequent progression to nonalcoholic steatohepatitis and cirrhosis (insulin resistance and hyperinsulinemia, oxidative stress, hepatic stellate cell activation, cytokine/adipocytokine signaling pathways, and genetic and environmental factors) appear to play a significant role in the development of NAFLD-related HCC. However, a comprehensive view of molecular mechanisms linking obesity, T2DM, and NAFLD-related HCC, as well as the exact sequence of molecular events, is still not understood in its entirety. Good-quality data are still necessary, and efforts should continue towards better understanding the underlying carcinogenic mechanisms of NAFLD-related HCC. In this paper, we aimed to centralize the most important links supporting these relationships, focusing on obesity, T2DM, and NAFLD-related HCC, as well as point out the major gaps in knowledge regarding the underlying molecular mechanisms behind them.
Collapse
|
125
|
Zheng H, Fu J, Xue P, Zhao R, Dong J, Liu D, Yamamoto M, Tong Q, Teng W, Qu W, Zhang Q, Andersen ME, Pi J. CNC-bZIP protein Nrf1-dependent regulation of glucose-stimulated insulin secretion. Antioxid Redox Signal 2015; 22:819-31. [PMID: 25556857 PMCID: PMC4367236 DOI: 10.1089/ars.2014.6017] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AIMS The inability of pancreatic β-cells to secrete sufficient insulin in response to glucose stimulation is a major contributing factor to the development of type 2 diabetes (T2D). We investigated both the in vitro and in vivo effects of deficiency of nuclear factor-erythroid 2-related factor 1 (Nrf1) in β-cells on β-cell function and glucose homeostasis. RESULTS Silencing of Nrf1 in β-cells leads to a pre-T2D phenotype with disrupted glucose metabolism and impaired insulin secretion. Specifically, MIN6 β-cells with stable knockdown of Nrf1 (Nrf1-KD) and isolated islets from β-cell-specific Nrf1-knockout [Nrf1(b)-KO] mice displayed impaired glucose responsiveness, including elevated basal insulin release and decreased glucose-stimulated insulin secretion (GSIS). Nrf1(b)-KO mice exhibited severe fasting hyperinsulinemia, reduced GSIS, and glucose intolerance. Silencing of Nrf1 in MIN6 cells resulted in oxidative stress and altered glucose metabolism, with increases in both glucose uptake and aerobic glycolysis, which is associated with the elevated basal insulin release and reduced glucose responsiveness. The elevated glycolysis and reduced glucose responsiveness due to Nrf1 silencing likely result from altered expression of glucose metabolic enzymes, with induction of high-affinity hexokinase 1 and suppression of low-affinity glucokinase. INNOVATION Our study demonstrated a novel role of Nrf1 in regulating glucose metabolism and insulin secretion in β-cells and characterized Nrf1 as a key transcription factor that regulates the coupling of glycolysis and mitochondrial metabolism and GSIS. CONCLUSION Nrf1 plays critical roles in regulating glucose metabolism, mitochondrial function, and insulin secretion, suggesting that Nrf1 may be a novel target to improve the function of insulin-secreting β-cells.
Collapse
Affiliation(s)
- Hongzhi Zheng
- 1 The First Affiliated Hospital, China Medical University , Shenyang, China
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
126
|
Gandhi CR, Chaillet JR, Nalesnik MA, Kumar S, Dangi A, Demetris AJ, Ferrell R, Wu T, Divanovic S, Stankeiwicz T, Shaffer B, Stolz DB, Harvey SAK, Wang J, Starzl TE. Liver-specific deletion of augmenter of liver regeneration accelerates development of steatohepatitis and hepatocellular carcinoma in mice. Gastroenterology 2015; 148:379-391.e4. [PMID: 25448926 PMCID: PMC4802363 DOI: 10.1053/j.gastro.2014.10.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 10/06/2014] [Accepted: 10/07/2014] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS Augmenter of liver regeneration (ALR, encoded by GFER) is a widely distributed pleiotropic protein originally identified as a hepatic growth factor. However, little is known about its roles in hepatic physiology and pathology. We created mice with liver-specific deletion of ALR to study its function. METHODS We developed mice with liver-specific deletion of ALR (ALR-L-KO) using the albumin-Cre/LoxP system. Liver tissues were collected from ALR-L-KO mice and ALR(floxed/floxed) mice (controls) and analyzed by histology, reverse-transcription polymerase chain reaction, immunohistochemistry, electron microscopy, and techniques to measure fibrosis and lipids. Liver tissues from patients with and without advanced liver disease were determined by immunoblot analysis. RESULTS Two weeks after birth, livers of ALR-L-KO mice contained low levels of ALR and adenosine triphosphate (ATP); they had reduced mitochondrial respiratory function and increased oxidative stress, compared with livers from control mice, and had excessive steatosis, and hepatocyte apoptosis. Levels of carbamyl-palmitoyl transferase 1a and ATP synthase subunit ATP5G1 were reduced in livers of ALR-L-KO mice, indicating defects in mitochondrial fatty acid transport and ATP synthesis. Electron microscopy showed mitochondrial swelling with abnormalities in shapes and numbers of cristae. From weeks 2-4 after birth, levels of steatosis and apoptosis decreased in ALR-L-KO mice, and numbers of ALR-expressing cells increased, along with ATP levels. However, at weeks 4-8 after birth, livers became inflamed, with hepatocellular necrosis, ductular proliferation, and fibrosis; hepatocellular carcinoma developed by 1 year after birth in nearly 60% of the mice. Hepatic levels of ALR were also low in ob/ob mice and alcohol-fed mice with liver steatosis, compared with controls. Levels of ALR were lower in liver tissues from patients with advanced alcoholic liver disease and nonalcoholic steatohepatitis than in control liver tissues. CONCLUSIONS We developed mice with liver-specific deletion of ALR, and showed that it is required for mitochondrial function and lipid homeostasis in the liver. ALR-L-KO mice provide a useful model for investigating the pathogenesis of steatohepatitis and its complications.
Collapse
Affiliation(s)
- Chandrashekhar R Gandhi
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Surgery, University of Cincinnati, Cincinnati, Ohio; Cincinnati VA Medical Center, Cincinnati, Ohio; Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh, Pennsylvania.
| | - J Richard Chaillet
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pennsylvania
| | - Michael A Nalesnik
- Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh, Pennsylvania; Department of Pathology, University of Pittsburgh, Pennsylvania
| | - Sudhir Kumar
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Anil Dangi
- Department of Surgery, University of Cincinnati, Cincinnati, Ohio; Cincinnati VA Medical Center, Cincinnati, Ohio
| | - A Jake Demetris
- Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh, Pennsylvania; Department of Pathology, University of Pittsburgh, Pennsylvania
| | - Robert Ferrell
- School of Public Health, University of Pittsburgh, Pennsylvania
| | - Tong Wu
- Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana
| | - Senad Divanovic
- Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Traci Stankeiwicz
- Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Benjamin Shaffer
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pennsylvania
| | - Donna B Stolz
- Department of Cell Biology, University of Pittsburgh, Pennsylvania
| | | | - Jiang Wang
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Thomas E Starzl
- Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh, Pennsylvania
| |
Collapse
|
127
|
Ho DV, Chan JY. Induction of Herpud1 expression by ER stress is regulated by Nrf1. FEBS Lett 2015; 589:615-20. [PMID: 25637874 PMCID: PMC10084809 DOI: 10.1016/j.febslet.2015.01.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 01/16/2015] [Accepted: 01/20/2015] [Indexed: 12/30/2022]
Abstract
Herpud1 is an ER-localized protein that contributes to endoplasmic reticulum (ER) homeostasis by participating in the ER-associated protein degradation pathway. The Nrf1 transcription factor is important in cellular stress pathways. We show that loss of Nrf1 function results in decreased Herpud1 expression in cells and liver tissues. Expression of Herpud1 increases in response to ER stress, but not in Nrf1 knockout cells. Transactivation studies show that Nrf1 acts through antioxidant response elements located in the Herpud1 promoter, and chromatin immunoprecipitation demonstrates that Herpud1 is a direct Nrf1 target gene. These results indicate that Nrf1 is a transcriptional activator of Herpud1 expression during ER stress, and they suggest Nrf1 is a key player in the regulation of the ER stress response in cells.
Collapse
Affiliation(s)
- Daniel V Ho
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Sciences, Irvine, CA 92697, USA
| | - Jefferson Y Chan
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Sciences, Irvine, CA 92697, USA.
| |
Collapse
|
128
|
Abstract
Abundant evidence supports the belief of a causal relationship between cirrhosis and hepatocellular carcinoma, but one that differs between high- and low-incidence regions of the tumor. In high-incidence regions, the cirrhosis is of the macronodular variety, is typically asymptomatic, and is caused predominantly by chronic hepatitis B virus infection, whereas in low-incidence regions, the cirrhosis, although usually macronodular, may be micronodular, is commonly symptomatic and of long-standing, and is caused by chronic hepatitis C virus infection, alcohol abuse over many years, the metabolic syndrome, or hereditary hemochromatosis. In a minority of patients, hepatocellular carcinoma develops in the absence of cirrhosis, supporting a direct hepatocarcinogenic effect of some of the causal agents. Cirrhosis is the major risk factor for tumor formation in patients with chronic hepatitis C virus infection. This virus does not integrate into cellular DNA, and malignant transformation results from increased liver cell turnover induced by recurring injury and regeneration of cells in the context of persisting inflammation, oxidative DNA damage, fibrosis, cirrhosis, and changes induced by the virus at a DNA level that have yet to be fully defined. Hepatitis B virus causes malignant transformation by both direct and indirect routes. The direct route results, in part, from integration of the viral DNA into host cellular DNA; transcriptional activation of host growth regulatory genes by hepatitis B virus-encoded proteins; and effects on apoptosis, cell signaling, and DNA repair. The direct route may share some similarities with that of hepatitis C virus infection. The metabolic syndrome may cause malignant transformation by production of oxidative stress and the induction of a variety of mutations, including some in the p53 gene.
Collapse
Affiliation(s)
- Michael C Kew
- Department of Medicine, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa,
| |
Collapse
|
129
|
The C-terminal domain of Nrf1 negatively regulates the full-length CNC-bZIP factor and its shorter isoform LCR-F1/Nrf1β; both are also inhibited by the small dominant-negative Nrf1γ/δ isoforms that down-regulate ARE-battery gene expression. PLoS One 2014; 9:e109159. [PMID: 25290918 PMCID: PMC4188613 DOI: 10.1371/journal.pone.0109159] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 09/08/2014] [Indexed: 12/30/2022] Open
Abstract
The C-terminal domain (CTD, aa 686–741) of nuclear factor-erythroid 2 p45-related factor 1 (Nrf1) shares 53% amino acid sequence identity with the equivalent Neh3 domain of Nrf2, a homologous transcription factor. The Neh3 positively regulates Nrf2, but whether the Neh3-like (Neh3L) CTD of Nrf1 has a similar role in regulating Nrf1-target gene expression is unknown. Herein, we report that CTD negatively regulates the full-length Nrf1 (i.e. 120-kDa glycoprotein and 95-kDa deglycoprotein) and its shorter isoform LCR-F1/Nrf1β (55-kDa). Attachment of its CTD-adjoining 112-aa to the C-terminus of Nrf2 yields the chimaeric Nrf2-C112Nrf1 factor with a markedly decreased activity. Live-cell imaging of GFP-CTD reveals that the extra-nuclear portion of the fusion protein is allowed to associate with the endoplasmic reticulum (ER) membrane through the amphipathic Neh3L region of Nrf1 and its basic c-tail. Thus removal of either the entire CTD or the essential Neh3L portion within CTD from Nrf1, LCR-F1/Nrf1β and Nrf2-C112Nrf1, results in an increase in their transcriptional ability to regulate antioxidant response element (ARE)-driven reporter genes. Further examinations unravel that two smaller isoforms, 36-kDa Nrf1γ and 25-kDa Nrf1δ, act as dominant-negative inhibitors to compete against Nrf1, LCR-F1/Nrf1β and Nrf2. Relative to Nrf1, LCR-F1/Nrf1β is a weak activator, that is positively regulated by its Asn/Ser/Thr-rich (NST) domain and acidic domain 2 (AD2). Like AD1 of Nrf1, both AD2 and NST domain of LCR-F1/Nrf1β fused within two different chimaeric contexts to yield Gal4D:Nrf1β607 and Nrf1β:C270Nrf2, positively regulate their transactivation activity of cognate Gal4- and Nrf2-target reporter genes. More importantly, differential expression of endogenous ARE-battery genes is attributable to up-regulation by Nrf1 and LCR-F1/Nrf1β and down-regulation by Nrf1γ and Nrf1δ.
Collapse
|
130
|
Transcription factor Nrf1 negatively regulates the cystine/glutamate transporter and lipid-metabolizing enzymes. Mol Cell Biol 2014; 34:3800-16. [PMID: 25092871 DOI: 10.1128/mcb.00110-14] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Liver-specific Nrf1 (NF-E2-p45-related factor 1) knockout mice develop nonalcoholic steatohepatitis. To identify postnatal mechanisms responsible for this phenotype, we generated an inducible liver-specific Nrf1 knockout mouse line using animals harboring an Nrf1(flox) allele and a rat CYP1A1-Cre transgene (Nrf1(flox/flox)::CYP1A1-Cre mice). Administration of 3-methylcholanthrene (3-MC) to these mice (Nrf1(flox/flox)::CYP1A1-Cre+3MC mice) resulted in loss of hepatic Nrf1 expression. The livers of mice lacking Nrf1 accumulated lipid, and the hepatic fatty acid (FA) composition in such animals differed significantly from that in the Nrf1(flox/flox)::CYP1A1-Cre control. This change was provoked by upregulation of several FA metabolism genes. Unexpectedly, we also found that the level of glutathione was increased dramatically in livers of Nrf1(flox/flox)::CYP1A1-Cre+3MC mice. While expression of glutathione biosynthetic enzymes was unchanged, xCT, a component of the cystine/glutamate antiporter system x(c)(-), was significantly upregulated in livers of Nrf1(flox/flox)::CYP1A1-Cre+3MC mice, suggesting that Nrf1 normally suppresses xCT. Thus, stress-inducible expression of xCT is a two-step process: under homeostatic conditions, Nrf1 effectively suppresses nonspecific transactivation of xCT, but when cells encounter severe oxidative/electrophilic stress, Nrf1 is displaced from an antioxidant response element (ARE) in the gene promoter while Nrf2 is recruited to the ARE. Thus, Nrf1 controls both the FA and the cystine/cysteine content of hepatocytes by participating in an elaborate regulatory network.
Collapse
|
131
|
Choi J, Corder NLB, Koduru B, Wang Y. Oxidative stress and hepatic Nox proteins in chronic hepatitis C and hepatocellular carcinoma. Free Radic Biol Med 2014; 72:267-84. [PMID: 24816297 PMCID: PMC4099059 DOI: 10.1016/j.freeradbiomed.2014.04.020] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 04/16/2014] [Accepted: 04/18/2014] [Indexed: 02/08/2023]
Abstract
Hepatocellular carcinoma (HCC) is the most common liver cancer and a leading cause of cancer-related mortality in the world. Hepatitis C virus (HCV) is a major etiologic agent of HCC. A majority of HCV infections lead to chronic infection that can progress to cirrhosis and, eventually, HCC and liver failure. A common pathogenic feature present in HCV infection, and other conditions leading to HCC, is oxidative stress. HCV directly increases superoxide and H2O2 formation in hepatocytes by elevating Nox protein expression and sensitizing mitochondria to reactive oxygen species generation while decreasing glutathione. Nitric oxide synthesis and hepatic iron are also elevated. Furthermore, activation of phagocytic NADPH oxidase (Nox) 2 of host immune cells is likely to exacerbate oxidative stress in HCV-infected patients. Key mechanisms of HCC include genome instability, epigenetic regulation, inflammation with chronic tissue injury and sustained cell proliferation, and modulation of cell growth and death. Oxidative stress, or Nox proteins, plays various roles in these mechanisms. Nox proteins also function in hepatic fibrosis, which commonly precedes HCC, and Nox4 elevation by HCV is mediated by transforming growth factor β. This review summarizes mechanisms of oncogenesis by HCV, highlighting the roles of oxidative stress and hepatic Nox enzymes in HCC.
Collapse
Affiliation(s)
- Jinah Choi
- School of Natural Sciences, University of California at Merced, Merced, CA 95343, USA.
| | - Nicole L B Corder
- School of Natural Sciences, University of California at Merced, Merced, CA 95343, USA
| | - Bhargav Koduru
- School of Natural Sciences, University of California at Merced, Merced, CA 95343, USA
| | - Yiyan Wang
- School of Natural Sciences, University of California at Merced, Merced, CA 95343, USA
| |
Collapse
|
132
|
Chheda TK, Shivakumar P, Sadasivan SK, Chanderasekharan H, Moolemath Y, Oommen AM, Madanahalli JR, Marikunte VV. Fast food diet with CCl4 micro-dose induced hepatic-fibrosis--a novel animal model. BMC Gastroenterol 2014; 14:89. [PMID: 24884574 PMCID: PMC4036109 DOI: 10.1186/1471-230x-14-89] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 05/06/2014] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is defined as a spectrum of conditions ranging from hepatocellular steatosis to steatohepatitis and fibrosis, progressing to cirrhosis, which occur in the absence of excessive alcohol use. Several animal models capture aspects of NAFLD but are limited either in their representation of the disease stages or use for development of therapeutics due to the extended periods of time required to develop full histological features. METHODS Here, we report the development of a novel rat model for NAFLD that addresses some of these limitations. We used a fast food diet (FFD) and a CCl4 micro dose (0.5 ml/kg B.wt) for 8 weeks in Wistar rats. Serological analyses, gene expression profiling and liver histology studies were conducted to investigate the development of steatosis, steatohepatitis and fibrosis in the FFD-CCl4 model when compared to the individual effects of a FFD or a micro dose of CCl4 in rats. RESULTS The serum biochemical profile of the FFD-CCl4 model showed an increase in liver injury and fibrosis. This was also accompanied by a significant increase in liver triglycerides (TG), inflammation and oxidative stress. Importantly, we observed extensive fibrosis confirmed by: i) increased gene expression of fibrosis markers and, ii) moderate to severe collagen deposition seen as perisinusoidal and bridging fibrosis using H&E, Trichome and Sirius Red staining. CONCLUSIONS In summary, we find that the FFD-CCl4 rat model developed NAFLD histological features including, steatosis, inflammation and fibrosis in 8 weeks showing promise as a model that can be used to develop NAFLD therapeutics and liver anti-fibrotics.
Collapse
|
133
|
Mobasher MA, Valverde ÁM. Signalling pathways involved in paracetamol-induced hepatotoxicity: new insights on the role of protein tyrosine phosphatase 1B. Arch Physiol Biochem 2014; 120:51-63. [PMID: 24738658 DOI: 10.3109/13813455.2014.893365] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Acute hepatic failure secondary to paracetamol poisoning is associated with high mortality. Paracetamol-induced hepatotoxicity causes oxidative stress that triggers signalling pathways and ultimately leads to lethal hepatocyte injury. We will review the signalling pathways activated by paracetamol in the liver emphasizing the role of protein tyrosine phosphatase 1B (PTP1B) in the balance between cell death and survival in hepatocytes. PTP1B has emerged as a key modulator of the antioxidant system mediated by the nuclear factor erythroid-2-related factor 2 (Nrf2) in hepatic cells in response to paracetamol overdose. Also, this phosphatase modulates the classical survival pathways triggered by the activation of the insulin-like growth factor-I (IGF-I) signalling cascade. Therefore, PTP1B is a novel therapeutic target against paracetamol-induced liver failure.
Collapse
Affiliation(s)
- Maysa Ahmed Mobasher
- Instituto de Investigaciones Biomédicas Alberto Sols (CSIC-UAM), 28029 Madrid, Spain, and Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) , ISCIII , Spain
| | | |
Collapse
|
134
|
Zhang Y, Ren Y, Li S, Hayes JD. Transcription factor Nrf1 is topologically repartitioned across membranes to enable target gene transactivation through its acidic glucose-responsive domains. PLoS One 2014; 9:e93458. [PMID: 24695487 PMCID: PMC3973704 DOI: 10.1371/journal.pone.0093458] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Accepted: 03/05/2014] [Indexed: 01/12/2023] Open
Abstract
The membrane-bound Nrf1 transcription factor regulates critical homeostatic and developmental genes. The conserved N-terminal homology box 1 (NHB1) sequence in Nrf1 targets the cap‘n’collar (CNC) basic basic-region leucine zipper (bZIP) factor to the endoplasmic reticulum (ER), but it is unknown how its activity is controlled topologically within membranes. Herein, we report a hitherto unknown mechanism by which the transactivation activity of Nrf1 is controlled through its membrane-topology. Thus after Nrf1 is anchored within ER membranes, its acidic transactivation domains (TADs), including the Asn/Ser/Thr-rich (NST) glycodomain situated between acidic domain 1 (AD1) and AD2, are transiently translocated into the lumen of the ER, where NST is glycosylated in the presence of glucose to yield an inactive 120-kDa Nrf1 glycoprotein. Subsequently, portions of the TADs partially repartition across membranes into the cyto/nucleoplasmic compartments, whereupon an active 95-kDa form of Nrf1 accumulates, a process that is more obvious in glucose-deprived cells and may involve deglycosylation. The repartitioning of Nrf1 out of membranes is monitored within this protein by its acidic-hydrophobic amphipathic glucose-responsive domains, particularly the Neh5L subdomain within AD1. Therefore, the membrane-topological organization of Nrf1 dictates its post-translational modifications (i.e. glycosylation, the putative deglycosylation and selective proteolysis), which together control its ability to transactivate target genes.
Collapse
Affiliation(s)
- Yiguo Zhang
- The NSFC-funded Laboratory of Cell Biochemistry and Gene Regulation, College of Medical Bioengineering and Faculty of Life Sciences, Chongqing University, Chongqing, China
- Division of Cancer Research, Medical Research Institute, Ninewells Hospital & Medical School, University of Dundee, Scotland, United Kingdom
- * E-mail:
| | - Yonggang Ren
- The NSFC-funded Laboratory of Cell Biochemistry and Gene Regulation, College of Medical Bioengineering and Faculty of Life Sciences, Chongqing University, Chongqing, China
| | - Shaojun Li
- The NSFC-funded Laboratory of Cell Biochemistry and Gene Regulation, College of Medical Bioengineering and Faculty of Life Sciences, Chongqing University, Chongqing, China
| | - John D. Hayes
- Division of Cancer Research, Medical Research Institute, Ninewells Hospital & Medical School, University of Dundee, Scotland, United Kingdom
| |
Collapse
|
135
|
Abstract
Obesity is an established risk factor for many types of cancers, particularly for hepatocellular carcinoma (HCC), owing to its carcinogenic potential and the association with nonalcoholic fatty liver disease (NAFLD). HCC may develop in cirrhotic and noncirrhotic livers with NAFLD, particularly in the presence of multiple metabolic risk factors such as obesity and diabetes. This issue is alarming because the population potentially at higher risk is greatly increasing. This review summarizes current evidence linking obesity and liver cancer, and discusses recent advances on the mechanisms underlying this relationship.
Collapse
|
136
|
Song MO, Mattie MD, Lee CH, Freedman JH. The role of Nrf1 and Nrf2 in the regulation of copper-responsive transcription. Exp Cell Res 2014; 322:39-50. [PMID: 24462598 DOI: 10.1016/j.yexcr.2014.01.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 02/06/2023]
Abstract
Recent evidences indicated Nrf2 is more potent than Nrf1 in the activation of antioxidant genes. However, the roles of Nrf proteins in the regulation of copper-responsive transcription have not been well addressed. We took the toxicogenomic approach and the present network and Gene Ontology analyses results showed that Nrf1 and Nrf2 are distinctively involved in copper-responsive transcriptional regulation in HepG2 transcriptome. Cells deficient in either Nrf1 or Nrf2 were more susceptible to copper exposure than wild type cells. Nrf1 and Nrf2 null cells were transfected with the luciferase reporters containing either ARE(s) or a combination of ARE(s) and MREs, and then treated with copper. In Nrf2-null (Nrf2(-/-)) cells, copper did not activate transcription of reporter genes, whereas Nrf1 deficiency did not affect copper-inducible activation. Ectopic expression of Nrf2 restored copper-inducible transcription in Nrf2(-/-) cells. However, the changes in the intrinsic mRNA levels of MT-1 in Nrf null cells following copper treatment showed that Nrf1 and Nrf2 equally contributed to MT-1 activation after 4h, while Nrf1involved more than Nrf2 following 24h exposure. These results suggest that while Nrf2 is crucial for MRE/ARE-mediated transcription in response to copper, Nrf1 may activate MT-1 expression by a mechanism different from that Nrf2 employs.
Collapse
Affiliation(s)
- Min Ok Song
- Department of Biology, College of Natural Sciences, Gangneung-Wonju National University, Gangwon-do 210-702, Republic of Korea.
| | - Michael D Mattie
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, USA.
| | - Chang-Ho Lee
- Department of Biology, College of Natural Sciences, Gangneung-Wonju National University, Gangwon-do 210-702, Republic of Korea
| | - Jonathan H Freedman
- Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| |
Collapse
|
137
|
Eriocitrin ameliorates diet-induced hepatic steatosis with activation of mitochondrial biogenesis. Sci Rep 2014; 4:3708. [PMID: 24424211 PMCID: PMC3892443 DOI: 10.1038/srep03708] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 12/10/2013] [Indexed: 02/06/2023] Open
Abstract
Lemon (Citrus limon) contains various bioactive flavonoids, and prevents obesity and obesity-associated metabolic diseases. We focused on eriocitrin (eriodictyol 7-rutinoside), a powerful antioxidative flavonoid in lemon with lipid-lowering effects in a rat model of high-fat diet. To investigate the mechanism of action of eriocitrin, we conducted feeding experiments on zebrafish with diet-induced obesity. Oral administration of eriocitrin (32 mg/kg/day for 28 days) improved dyslipidaemia and decreased lipid droplets in the liver. DNA microarray analysis revealed that eriocitrin increased mRNA of mitochondrial biogenesis genes, such as mitochondria transcription factor, nuclear respiratory factor 1, cytochrome c oxidase subunit 4, and ATP synthase. In HepG2 cells, eriocitrin also induced the corresponding orthologues, and reduced lipid accumulation under conditions of lipid loading. Eriocitrin increased mitochondrial size and mtDNA content, which resulted in ATP production in HepG2 cells and zebrafish. In summary, dietary eriocitrin ameliorates diet-induced hepatic steatosis with activation of mitochondrial biogenesis.
Collapse
|
138
|
Abstract
Nrf2:INrf2 (Keap1) are cellular sensors of oxidative and electrophilic stress. Nrf2 is a nuclear factor that controls the expression and coordinated induction of a battery of genes that encode detoxifying enzymes, drug transporters, antiapoptotic proteins, and proteasomes. In the basal state, Nrf2 is constantly degraded in the cytoplasm by its inhibitor, INrf2. INrf2 functions as an adapter for Cul3/Rbx1 E3 ubiquitin ligase-mediated degradation of Nrf2. Chemicals, including antioxidants, tocopherols including α-tocopherol (vitamin E), and phytochemicals, and radiation antagonize the Nrf2:INrf2 interaction and lead to the stabilization and activation of Nrf2. The signaling events involve preinduction, induction, and postinduction responses that tightly control Nrf2 activation and repression back to the basal state. Oxidative/electrophilic signals activate unknown tyrosine kinases in a preinduction response that phosphorylates specific residues on Nrf2 negative regulators, INrf2, Fyn, and Bach1, leading to their nuclear export, ubiquitination, and degradation. This prepares nuclei for unhindered import of Nrf2. Oxidative/electrophilic modification of INrf2 cysteine 151 followed by PKC phosphorylation of Nrf2 serine 40 in the induction response results in the escape or release of Nrf2 from INrf2. Nrf2 is thus stabilized and translocates to the nucleus, resulting in a coordinated activation of gene expression. This is followed by a postinduction response that controls the "switching off" of Nrf2-activated gene expression. GSK3β, under the control of AKT and PI3K, phosphorylates Fyn, leading to Fyn nuclear localization. Fyn phosphorylates Nrf2 Y568, resulting in nuclear export and degradation of Nrf2. The activation and repression of Nrf2 provide protection against oxidative/electrophilic stress and associated diseases, including cancer. However, deregulation of INrf2 and Nrf2 due to mutations may lead to nuclear accumulation of Nrf2 that reduces apoptosis and promotes oncogenesis and drug resistance.
Collapse
Affiliation(s)
- Suryakant K Niture
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Raju Khatri
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Anil K Jaiswal
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| |
Collapse
|
139
|
Williams LM, Timme-Laragy AR, Goldstone JV, McArthur AG, Stegeman JJ, Smolowitz RM, Hahn ME. Developmental expression of the Nfe2-related factor (Nrf) transcription factor family in the zebrafish, Danio rerio. PLoS One 2013; 8:e79574. [PMID: 24298298 PMCID: PMC3840143 DOI: 10.1371/journal.pone.0079574] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 09/24/2013] [Indexed: 12/30/2022] Open
Abstract
Transcription factors in the CNC-bZIP family (NFE2, NRF1, NRF2 and NRF3) regulate genes with a wide range of functions in response to both physiological and exogenous signals, including those indicating changes in cellular redox status. Given their role in helping to maintain cellular homeostasis, it is imperative to understand the expression, regulation, and function of CNC-bZIP genes during embryonic development. We explored the expression and function of six nrf genes (nfe2, nrf1a, nrf1b, nrf2a, nrf2b, and nrf3) using zebrafish embryos as a model system. Analysis by microarray and quantitative RT-PCR showed that genes in the nrf family were expressed throughout development from oocytes to larvae. The spatial expression of nrf3 suggested a role in regulating the development of the brain, brachia and pectoral fins. Knock-down by morpholino anti-sense oligonucleotides suggested that none of the genes were necessary for embryonic viability, but nfe2 was required for proper cellular organization in the pneumatic duct and subsequent swim bladder function, as well as for proper formation of the otic vesicles. nrf genes were induced by the oxidant tert-butylhydroperoxide, and some of this response was regulated through family members Nrf2a and Nrf2b. Our results provide a foundation for understanding the role of nrf genes in normal development and in regulating the response to oxidative stress in vertebrate embryos.
Collapse
Affiliation(s)
- Larissa M. Williams
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
- Biology Department, Bates College, Lewiston, Maine, United States of America
| | - Alicia R. Timme-Laragy
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
| | - Jared V. Goldstone
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
| | | | - John J. Stegeman
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
| | - Roxanna M. Smolowitz
- Department of Biology and Marine Biology, Roger Williams University, Bristol, Rhode Island, United States of America
| | - Mark E. Hahn
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
140
|
Zhang Y, Hayes JD. The membrane-topogenic vectorial behaviour of Nrf1 controls its post-translational modification and transactivation activity. Sci Rep 2013; 3:2006. [PMID: 23774320 PMCID: PMC3684815 DOI: 10.1038/srep02006] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 05/30/2013] [Indexed: 12/17/2022] Open
Abstract
The integral membrane-bound Nrf1 transcription factor fulfils important functions in maintaining cellular homeostasis and organ integrity, but how it is controlled vectorially is unknown. Herein, creative use of Gal4-based reporter assays with protease protection assays (GRAPPA), and double fluorescence protease protection (dFPP), reveals that the membrane-topogenic vectorial behaviour of Nrf1 dictates its post-translational modification and transactivation activity. Nrf1 is integrated within endoplasmic reticulum (ER) membranes through its NHB1-associated TM1 in cooperation with other semihydrophobic amphipathic regions. The transactivation domains (TADs) of Nrf1, including its Asn/Ser/Thr-rich (NST) glycodomain, are transiently translocated into the ER lumen, where it is glycosylated in the presence of glucose to become a 120-kDa isoform. Thereafter, the NST-adjoining TADs are partially repartitioned out of membranes into the cyto/nucleoplasmic side, where Nrf1 is subject to deglycosylation and/or proteolysis to generate 95-kDa and 85-kDa isoforms. Therefore, the vectorial process of Nrf1 controls its target gene expression.
Collapse
Affiliation(s)
- Yiguo Zhang
- The NSFC-funded Laboratory of Cell Biochemistry and Gene Regulation, College of Medical Bioengineering and Faculty of Life Sciences, University of Chongqing, Shapingba District, Chongqing, China.
| | | |
Collapse
|
141
|
Xu C, Zhao W, Hao Y, Chang C, Fan J. Comparative analysis of gene expression profiles of acute hepatic failure and that of liver regeneration in rat. Gene 2013; 528:59-66. [DOI: 10.1016/j.gene.2013.07.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 06/28/2013] [Accepted: 07/02/2013] [Indexed: 01/18/2023]
|
142
|
Cesaratto L, Codarin E, Vascotto C, Leonardi A, Kelley MR, Tiribelli C, Tell G. Specific inhibition of the redox activity of ape1/ref-1 by e3330 blocks tnf-α-induced activation of IL-8 production in liver cancer cell lines. PLoS One 2013; 8:e70909. [PMID: 23967134 PMCID: PMC3744539 DOI: 10.1371/journal.pone.0070909] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 06/24/2013] [Indexed: 12/23/2022] Open
Abstract
APE1/Ref-1 is a main regulator of cellular response to oxidative stress via DNA-repair function and co-activating activity on the NF-κB transcription factor. APE1 is central in controlling the oxidative stress-based inflammatory processes through modulation of cytokines expression and its overexpression is responsible for the onset of chemoresistance in different tumors including hepatic cancer. We examined the functional role of APE1 overexpression during hepatic cell damage related to fatty acid accumulation and the role of the redox function of APE1 in the inflammatory process. HepG2 cells were stably transfected with functional and non-functional APE1 encoding plasmids and the protective effect of APE1 overexpression toward genotoxic compounds or FAs accumulation, was tested. JHH6 cells were stimulated with TNF-α in the presence or absence of E3330, an APE1 redox inhibitor. IL-8 promoter activity was assessed by a luciferase reporter assay, gene expression by Real-Time PCR and cytokines (IL-6, IL-8, IL-12) levels measured by ELISA. APE1 over-expression did not prevent cytotoxicity induced by lipid accumulation. E3330 treatment prevented the functional activation of NF-κB via the alteration of APE1 subcellular trafficking and reduced IL-6 and IL-8 expression induced by TNF-α and FAs accumulation through blockage of the redox-mediated activation of NF-κB. APE1 overexpression observed in hepatic cancer cells may reflect an adaptive response to cell damage and may be responsible for further cell resistance to chemotherapy and for the onset of inflammatory response. The efficacy of the inhibition of APE1 redox activity in blocking TNF-α and FAs induced inflammatory response opens new perspectives for treatment of inflammatory-based liver diseases.
Collapse
Affiliation(s)
- Laura Cesaratto
- Dipartimento di Scienze Mediche e Biologiche, Università di Udine, Udine, Italy
- Fondazione Italiana Fegato, AREA Science Park, Basovizza, Trieste, Italy
| | - Erika Codarin
- Dipartimento di Scienze Mediche e Biologiche, Università di Udine, Udine, Italy
| | - Carlo Vascotto
- Dipartimento di Scienze Mediche e Biologiche, Università di Udine, Udine, Italy
| | - Antonio Leonardi
- Dipartimento di Patologia Cellulare e Molecolare ‘L. Califano’ Università “Federico II” di Napoli, Napoli, Italy
| | - Mark R. Kelley
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University, Indianapolis, Indiana, United States of America
| | - Claudio Tiribelli
- Fondazione Italiana Fegato, AREA Science Park, Basovizza, Trieste, Italy
- Dipartimento Scienze Cliniche, Università di Trieste, Trieste, Italy
| | - Gianluca Tell
- Dipartimento di Scienze Mediche e Biologiche, Università di Udine, Udine, Italy
- * E-mail:
| |
Collapse
|
143
|
The casein kinase 2-nrf1 axis controls the clearance of ubiquitinated proteins by regulating proteasome gene expression. Mol Cell Biol 2013; 33:3461-72. [PMID: 23816881 DOI: 10.1128/mcb.01271-12] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Impairment of the ubiquitin-proteasome system (UPS) has been implicated in the pathogenesis of human diseases, including neurodegenerative disorders. Thus, stimulating proteasome activity is a promising strategy to ameliorate these age-related diseases. Here we show that the protein kinase casein kinase 2 (CK2) regulates the transcriptional activity of Nrf1 to control the expression of the proteasome genes and thus the clearance of ubiquitinated proteins. We identify CK2 as an Nrf1-binding protein and find that the knockdown of CK2 enhances the Nrf1-dependent expression of the proteasome subunit genes. Real-time monitoring of proteasome activity reveals that CK2 knockdown alleviates the accumulation of ubiquitinated proteins upon proteasome inhibition. Furthermore, we identify Ser 497 of Nrf1 as the CK2 phosphorylation site and demonstrate that its alanine substitution (S497A) augments the transcriptional activity of Nrf1 and mitigates proteasome dysfunction and the formation of p62-positive juxtanuclear inclusion bodies upon proteasome inhibition. These results indicate that the CK2-mediated phosphorylation of Nrf1 suppresses the proteasome gene expression and activity and thus suggest that the CK2-Nrf1 axis is a potential therapeutic target for diseases associated with UPS impairment.
Collapse
|
144
|
Lee CS, Ho DV, Chan JY. Nuclear factor-erythroid 2-related factor 1 regulates expression of proteasome genes in hepatocytes and protects against endoplasmic reticulum stress and steatosis in mice. FEBS J 2013; 280:3609-20. [PMID: 23702335 DOI: 10.1111/febs.12350] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 05/14/2013] [Accepted: 05/20/2013] [Indexed: 12/22/2022]
Abstract
The ubiquitin-proteasome system is important in maintaining protein homeostasis. NFE2-related factor 1 (Nrf1), a transcription factor in the cap 'n' collar basic-leucine zipper family, regulates expression of cytoprotective genes. It was previously shown that liver-specific knockout of Nrf1 (Nrf1LKO) leads to hepatic cell death, steatohepatitis and cancer. However, the mechanisms underlying these pathologies are not clear. Here, we report that Nrf1 is critical for proteasome gene expression in the liver. Liver-specific knockout of Nrf1 results in impaired basal and induced expression of proteasome genes, and diminished proteasome activity in hepatocytes. In addition, our findings demonstrated that endoplasmic reticulum stress signaling pathway was also activated in Nrf1LKO livers. Inhibition of proteasome activity leads to endoplasmic reticulum stress in Nrf1-deficient hepatocytes, prompting the development of steatosis in the liver. Our results indicate that Nrf1 plays an integral role in the maintenance of proteasome function in hepatocytes and in the prevention of liver steatosis development. Moreover, these results highlight an association between proteasome dysfunction, endoplasmic reticulum stress and steatosis.
Collapse
Affiliation(s)
- Candy S Lee
- Department of Laboratory Medicine and Pathology, University of California Irvine, Irvine, CA 92697, USA
| | | | | |
Collapse
|
145
|
Biswas M, Kwong EK, Park E, Nagra P, Chan JY. Glycogen synthase kinase 3 regulates expression of nuclear factor-erythroid-2 related transcription factor-1 (Nrf1) and inhibits pro-survival function of Nrf1. Exp Cell Res 2013; 319:1922-1931. [PMID: 23623971 DOI: 10.1016/j.yexcr.2013.04.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 03/29/2013] [Accepted: 04/16/2013] [Indexed: 12/30/2022]
Abstract
Nuclear factor E2-related factor-1 (Nrf1) is a basic leucine zipper transcription factor that is known to regulate antioxidant and cytoprotective gene expression. It was recently shown that Nrf1 is regulated by SCF-Fbw7 ubiquitin ligase. However our knowledge of upstream signals that targets Nrf1 for degradation by the UPS is not known. We report here that Nrf1 expression is negatively regulated by glycogen synthase kinase 3 (GSK3) in Fbw7-dependent manner. We show that GSK3 interacts with Nrf1 and phosphorylates the Cdc4 phosphodegron domain (CPD) in Nrf1. Mutation of serine residue in the CPD of Nrf1 to alanine (S350A), blocks Nrf1 from phosphorylation by GSK3, and stabilizes Nrf1. Knockdown of Nrf1 and expression of a constitutively active form of GSK3 results in increased apoptosis in neuronal cells in response to ER stress, while expression of the GSK3 phosphorylation resistant S350A-Nrf1 attenuates apoptotic cell death. Together these data suggest that GSK3 regulates Nrf1 expression and cell survival function in response to stress activation.
Collapse
Affiliation(s)
- Madhurima Biswas
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Science 1, Irvine, CA 92697, USA
| | - Erick K Kwong
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Science 1, Irvine, CA 92697, USA
| | - Eujean Park
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Science 1, Irvine, CA 92697, USA
| | - Parminder Nagra
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Science 1, Irvine, CA 92697, USA
| | - Jefferson Y Chan
- Department of Laboratory Medicine and Pathology, University of California, Irvine, D440 Medical Science 1, Irvine, CA 92697, USA.
| |
Collapse
|
146
|
Alterations in the redox state and liver damage: hints from the EASL Basic School of Hepatology. J Hepatol 2013; 58:365-74. [PMID: 23023012 DOI: 10.1016/j.jhep.2012.09.018] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 08/27/2012] [Accepted: 09/19/2012] [Indexed: 12/19/2022]
Abstract
The importance of a correct balance between oxidative and reductive events has been shown to have a paramount effect on cell function for quite a long time. However, in spite of this body of rapidly growing evidence, the implication of the alteration of the redox state in human disease has been so far much less appreciated. Liver diseases make no exception. Although not fully comprehensive, this article reports what discussed during an EASL Basic School held in 2012 in Trieste, Italy, where the effect of the alteration of the redox state was addressed in different experimental and human models. This translational approach resulted in further stressing the concept that this topic should be expanded in the future not only to better understand how oxidative stress may be linked to a liver damage but also, perhaps more important, how this may be the target for better, more focused treatments. In parallel, understanding how alteration of the redox balance may be associated with liver damage may help define sensitive and ideally early biomarkers of the disorder.
Collapse
|
147
|
Shelton P, Jaiswal AK. The transcription factor NF-E2-related factor 2 (Nrf2): a protooncogene? FASEB J 2013; 27:414-23. [PMID: 23109674 PMCID: PMC3545532 DOI: 10.1096/fj.12-217257] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 10/15/2012] [Indexed: 12/13/2022]
Abstract
The transcription factor Nrf2 is responsible for regulating a battery of antioxidant and cellular protective genes, primarily in response to oxidative stress. A member of the cap 'n' collar family of transcription factors, Nrf2 activation is tightly controlled by a series of signaling events. These events can be separated into the basal state, a preinduction response, gene induction, and finally a postinduction response, culminating in the restoration of redox homeostasis. However, despite the immensely intricate level of control the cellular environment imposes on Nrf2 activity, there are many opportunities for perturbations to arise in the signaling events that favor carcinogenesis and, therefore, implicate Nrf2 as both a tumor suppressor and a protooncogene. Herein, we highlight the ways in which Nrf2 is regulated, and discuss some of the Nrf2-inducible antioxidant (NQO1, NQO2, HO-1, GCLC), antiapoptotic (Bcl-2), metabolic (G6PD, TKT, PPARγ), and drug efflux transporter (ABCG2, MRP3, MRP4) genes. In addition, we focus on how Nrf2 functions as a tumor suppressor under normal conditions and how its ability to detoxify the cellular environment makes it an attractive target for other oncogenes either via stabilization or degradation of the transcription factor. Finally, we discuss some of the ways in which Nrf2 is being considered as a therapeutic target for cancer treatment.
Collapse
Affiliation(s)
- Phillip Shelton
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Anil K. Jaiswal
- Department of Pharmacology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| |
Collapse
|
148
|
Ivanov AV, Bartosch B, Smirnova OA, Isaguliants MG, Kochetkov SN. HCV and oxidative stress in the liver. Viruses 2013; 5:439-69. [PMID: 23358390 PMCID: PMC3640510 DOI: 10.3390/v5020439] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 12/26/2012] [Accepted: 01/17/2013] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) is the etiological agent accounting for chronic liver disease in approximately 2-3% of the population worldwide. HCV infection often leads to liver fibrosis and cirrhosis, various metabolic alterations including steatosis, insulin and interferon resistance or iron overload, and development of hepatocellular carcinoma or non-Hodgkin lymphoma. Multiple molecular mechanisms that trigger the emergence and development of each of these pathogenic processes have been identified so far. One of these involves marked induction of a reactive oxygen species (ROS) in infected cells leading to oxidative stress. To date, markers of oxidative stress were observed both in chronic hepatitis C patients and in various in vitro systems, including replicons or stable cell lines expressing viral proteins. The search for ROS sources in HCV-infected cells revealed several mechanisms of ROS production and thus a number of cellular proteins have become targets for future studies. Furthermore, during last several years it has been shown that HCV modifies antioxidant defense mechanisms. The aim of this review is to summarize the present state of art in the field and to try to predict directions for future studies.
Collapse
Affiliation(s)
- Alexander V. Ivanov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str., 32, Moscow 119991, Russia; E-Mails: (A.I.); (O.S.); (S.K.)
| | - Birke Bartosch
- CRCL, INSERM U1052, CNRS 5286, Université de Lyon, 151, Cours A Thomas 69424 Lyon Cedex France; E-Mail:
| | - Olga A. Smirnova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str., 32, Moscow 119991, Russia; E-Mails: (A.I.); (O.S.); (S.K.)
| | - Maria G. Isaguliants
- Department of Molecular Biology, Tumor and Cell Biology, Karolinska Institutet, Nobels väg 16 17177 Stockholm, Sweden; E-Mail:
- D.I. Ivanovsky Institute of Virology, Gamaleya Str. 16, 123098 Moscow, Russia; E-Mail:
| | - Sergey N. Kochetkov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str., 32, Moscow 119991, Russia; E-Mails: (A.I.); (O.S.); (S.K.)
| |
Collapse
|
149
|
Ye P, Cheah IK, Halliwell B. High fat diets and pathology in the guinea pig. Atherosclerosis or liver damage? Biochim Biophys Acta Mol Basis Dis 2012. [PMID: 23195951 DOI: 10.1016/j.bbadis.2012.11.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Animal models have been widely used to investigate the relationship between diet and atherosclerosis and also to study disease etiology and possible interventions. Guinea pigs have been suggested to be a more "realistic" model for atherosclerosis due to their many similarities to humans. However, few published studies actually reported observations of characteristic atherosclerotic lesions and even fewer of advanced lesions. Studies, by our group, of guinea pigs fed on a high-fat diet revealed similar observations, with indications primarily of fatty streaks but little evidence of atherosclerotic plaques. This review discusses the feasibility of the guinea pig as a model for dietary-induced atherosclerosis. As it stands, current evidence raises doubt as to whether guinea pigs could serve as a realistic model for atherosclerosis. However, our own data and the literature suggest that they could be useful models for studying lipoprotein metabolism, non-alcoholic fatty liver disease, and dietary interventions which may help regulate these conditions.
Collapse
Affiliation(s)
- Peng Ye
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore
| | | | | |
Collapse
|
150
|
Kwong EK, Kim KM, Penalosa PJ, Chan JY. Characterization of Nrf1b, a novel isoform of the nuclear factor-erythroid-2 related transcription factor-1 that activates antioxidant response element-regulated genes. PLoS One 2012; 7:e48404. [PMID: 23144760 PMCID: PMC3483171 DOI: 10.1371/journal.pone.0048404] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 10/01/2012] [Indexed: 12/30/2022] Open
Abstract
Nuclear factor E2-related factor 1 (Nrf1) is a basic leucine zipper transcription factor that plays an important role in the activation of cytoprotective genes through the antioxidant response elements. The previously characterized long isoform of Nrf1 (Nrf1a) is targeted to the endoplasmic reticulum and accumulates in the nucleus in response to activating signals. Here we characterized a novel Nrf1 protein isoform (Nrf1b) generated through an alternative promoter and first exon that lacks the ER targeting domain of Nrf1a. The 5′-flanking region of Nrf1b directed high levels of luciferase reporter expression in cells. RT-PCR and Western blotting showed Nrf1b is widely expressed in various cell lines and mouse tissues. Immunoblot analysis of subcellular fractions and imaging of green fluorescence protein (GFP)-tagged Nrf1b demonstrate Nrf1b is constitutively localized to the nucleus. Nrf1b can activate GAL4-dependent transcription when fused to the heterologous GAL4 DNA-binding domain. Gel-shift and coimmunoprecipitation experiments demonstrate that Nrf1b forms a complex with MafG, and expression of Nrf1b activates the expression of antioxidant response element containing reporters and genes in cells. These results suggest Nrf1b is targeted to the nucleus where it activates ARE-driven genes and may play a role in modulating antioxidant response elements.
Collapse
Affiliation(s)
- Eric K. Kwong
- Department of Laboratory Medicine and Pathology, University of California Irvine, Irvine, California, United States of America
| | - Kyung-Mi Kim
- Department of Laboratory Medicine and Pathology, University of California Irvine, Irvine, California, United States of America
| | - Patrick J. Penalosa
- Department of Laboratory Medicine and Pathology, University of California Irvine, Irvine, California, United States of America
| | - Jefferson Y. Chan
- Department of Laboratory Medicine and Pathology, University of California Irvine, Irvine, California, United States of America
- * E-mail:
| |
Collapse
|