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Miyachi Y, Miyazawa T, Ogawa Y. HNF1A Mutations and Beta Cell Dysfunction in Diabetes. Int J Mol Sci 2022; 23:ijms23063222. [PMID: 35328643 PMCID: PMC8948720 DOI: 10.3390/ijms23063222] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 12/26/2022] Open
Abstract
Understanding the genetic factors of diabetes is essential for addressing the global increase in type 2 diabetes. HNF1A mutations cause a monogenic form of diabetes called maturity-onset diabetes of the young (MODY), and HNF1A single-nucleotide polymorphisms are associated with the development of type 2 diabetes. Numerous studies have been conducted, mainly using genetically modified mice, to explore the molecular basis for the development of diabetes caused by HNF1A mutations, and to reveal the roles of HNF1A in multiple organs, including insulin secretion from pancreatic beta cells, lipid metabolism and protein synthesis in the liver, and urinary glucose reabsorption in the kidneys. Recent studies using human stem cells that mimic MODY have provided new insights into beta cell dysfunction. In this article, we discuss the involvement of HNF1A in beta cell dysfunction by reviewing previous studies using genetically modified mice and recent findings in human stem cell-derived beta cells.
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Li LM, Jiang BG, Sun LL. HNF1A:From Monogenic Diabetes to Type 2 Diabetes and Gestational Diabetes Mellitus. Front Endocrinol (Lausanne) 2022; 13:829565. [PMID: 35299962 PMCID: PMC8921476 DOI: 10.3389/fendo.2022.829565] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 02/03/2022] [Indexed: 12/12/2022] Open
Abstract
Diabetes, a disease characterized by hyperglycemia, has a serious impact on the lives and families of patients as well as on society. Diabetes is a group of highly heterogeneous metabolic diseases that can be classified as type 1 diabetes (T1D), type 2 diabetes (T2D), gestational diabetes mellitus (GDM), or other according to the etiology. The clinical manifestations are more or less similar among the different types of diabetes, and each type is highly heterogeneous due to different pathogenic factors. Therefore, distinguishing between various types of diabetes and defining their subtypes are major challenges hindering the precise treatment of the disease. T2D is the main type of diabetes in humans as well as the most heterogeneous. Fortunately, some studies have shown that variants of certain genes involved in monogenic diabetes also increase the risk of T2D. We hope this finding will enable breakthroughs regarding the pathogenesis of T2D and facilitate personalized treatment of the disease by exploring the function of the signal genes involved. Hepatocyte nuclear factor 1 homeobox A (HNF1α) is widely expressed in pancreatic β cells, the liver, the intestines, and other organs. HNF1α is highly polymorphic, but lacks a mutation hot spot. Mutations can be found at any site of the gene. Some single nucleotide polymorphisms (SNPs) cause maturity-onset diabetes of the young type 3 (MODY3) while some others do not cause MODY3 but increase the susceptibility to T2D or GDM. The phenotypes of MODY3 caused by different SNPs also differ. MODY3 is among the most common types of MODY, which is a form of monogenic diabetes mellitus caused by a single gene mutation. Both T2D and GDM are multifactorial diseases caused by both genetic and environmental factors. Different types of diabetes mellitus have different clinical phenotypes and treatments. This review focuses on HNF1α gene polymorphisms, HNF1A-MODY3, HNF1A-associated T2D and GDM, and the related pathogenesis and treatment methods. We hope this review will provide a valuable reference for the precise and individualized treatment of diabetes caused by abnormal HNF1α by summarizing the clinical heterogeneity of blood glucose abnormalities caused by HNF1α mutation.
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Affiliation(s)
- Li-Mei Li
- Research Center for Translational Medicine, Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Bei-Ge Jiang
- Third Department of Hepatic Surgery, Eastern Hepatobiliary Surgery Hospital, Naval Medical University, Shanghai, China
- *Correspondence: Bei-Ge Jiang, ; Liang-Liang Sun,
| | - Liang-Liang Sun
- Department of Endocrinology and Metabolism, Changzheng Hospital, Naval Medical University, Shanghai, China
- *Correspondence: Bei-Ge Jiang, ; Liang-Liang Sun,
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Hu M, Huang X, Han X, Ji L. Loss of HNF1α Function Contributes to Hepatocyte Proliferation and Abnormal Cholesterol Metabolism via Downregulating miR-122: A Novel Mechanism of MODY3. Diabetes Metab Syndr Obes 2020; 13:627-639. [PMID: 32184642 PMCID: PMC7060037 DOI: 10.2147/dmso.s236915] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 01/20/2020] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Mutations in hepatocyte nuclear factor 1α (HNF1α) are the cause of maturity-onset diabetes of the young type 3 (MODY3) and involved in the development of hepatocellular adenoma and abnormal lipid metabolism. Previously, we have found that the serum microRNA (miR)-122 levels in MODY3 patients were lower than those in type 2 diabetes mellitus and healthy controls. This study aimed to investigate the mechanism of decreased miR-122 levels in patients with MODY3 and whether low levels of miR-122 mediate tumorigenesis and abnormal lipid metabolism associated with HNF1α deficiency in human hepatocytes. METHODS The expression of miR-122 was examined by real-time PCR. Dual-luciferase reporter assay was performed to confirm the transcriptional regulation of miR-122 by HNF1α. HepG2 cells were transfected with siRNA or miRNA mimic to downregulate or upregulate the expression of HNF1α or miR-122, respectively. CCK-8 and colony formation assay were used to determine cell proliferation. Lipid accumulation was examined by Oil Red O staining and intracellular triglyceride and cholesterol quantification assays. RESULTS HNF1α regulated the expression of miR-122 by directly binding to its promoter. Knockdown of HNF1α in HepG2 cells reduced the expression of miR-122, increased proliferation and promoted intracellular cholesterol accumulation. Overexpression of miR-122 partially rescued the phenotypes associated with HNF1α deficiency in human hepatocytes. Mechanistically, HNF1α modulated cholesterol homeostasis via miR-122-dependent activation of sterol regulatory element-binding protein-2 (SREBP-2) and regulation of proprotein convertase subtilisin/kexin type 9 (PCSK9). Moreover, circulating miR-122 levels were associated with serum cholesterol levels. CONCLUSION Loss of HNF1α function led to hepatocyte proliferation and abnormal cholesterol metabolism by downregulating miR-122. Our findings revealed a novel mechanism that low levels of miR-122 mediate tumorigenesis and abnormal lipid metabolism associated with MODY3. MiR-122 may be a potential therapeutic target for the treatment of MODY3.
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Affiliation(s)
- Mengdie Hu
- Department of Endocrinology and Metabolism, Peking University People’s Hospital, Peking University Diabetes Center, Beijing100044, People’s Republic of China
| | - Xiuting Huang
- Department of Endocrinology and Metabolism, Peking University People’s Hospital, Peking University Diabetes Center, Beijing100044, People’s Republic of China
| | - Xueyao Han
- Department of Endocrinology and Metabolism, Peking University People’s Hospital, Peking University Diabetes Center, Beijing100044, People’s Republic of China
| | - Linong Ji
- Department of Endocrinology and Metabolism, Peking University People’s Hospital, Peking University Diabetes Center, Beijing100044, People’s Republic of China
- Correspondence: Linong Ji; Xueyao Han Department of Endocrinology and Metabolism, Peking University People’s Hospital, Peking University Diabetes Center, Beijing100044, People’s Republic of ChinaTel +86 10-8832 5578Fax +86 10-8832 4371 Email ;
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Wang X, Hassan W, Zhao J, Bakht S, Nie Y, Wang Y, Pang Q, Huang Z. The impact of hepatocyte nuclear factor-1α on liver malignancies and cell stemness with metabolic consequences. Stem Cell Res Ther 2019; 10:315. [PMID: 31685031 PMCID: PMC6829964 DOI: 10.1186/s13287-019-1438-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/03/2019] [Accepted: 10/01/2019] [Indexed: 01/18/2023] Open
Abstract
Hepatocyte nuclear factor-1 alpha (HNF-1α) is a transcription factor expressed predominantly in the liver among other organs. Structurally, it contains POU-homeodomain that binds to DNA and form proteins that help in maintaining cellular homeostasis, controlling metabolism, and differentiating cell lineages. Scientific research over the period of three decades has reported it as an important player in various liver malignancies such as hepatocellular cancers (HCCs), hepatocellular adenoma (HA), and a more specific HNF-1α-inactivated human hepatocellular adenoma (H-HCAs). Abundant clinical and rodent data have noted the downregulation of HNF-1α in parallel with liver malignancies. It is also interesting to notice that the co-occurrence of mutated HNF-1α expression and hepatic carcinomas transpires typically along with metabolic repercussion. Moreover, scientific data implies that HNF-1α exerts its effects on cell stemness and hence can indirectly impact liver malignancies and metabolic functioning. The effects of HNF-1α on cell stemness present a future opportunity to explore a possible and potential breakthrough. Although the mechanism through which inactivated HNF-1α leads to hepatic malignancies remain largely obscure, several key signal molecules or pathways, including TNF-α, SHP-1, CDH17, SIRT, and MIA-2, have been reported to take part in the regulations of HNF-1α. It can be concluded from the present scientific data that HNF-1α has a great potential to serve as a target for liver malignancies and cell stemness.
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Affiliation(s)
- Xue Wang
- Laboratory of Cancer Epigenetics, Wuxi School of Medicine, Jiangnan University, Wuxi, China
| | - Waseem Hassan
- Department of Pharmacy, COMSATS University Islamabad, Lahore campus, Lahore, Pakistan
| | - Jing Zhao
- Laboratory of Cancer Epigenetics, Wuxi School of Medicine, Jiangnan University, Wuxi, China
| | - Sahar Bakht
- Department of Pharmacy, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
| | - Yunjuan Nie
- Laboratory of Cancer Epigenetics, Wuxi School of Medicine, Jiangnan University, Wuxi, China
| | - Ying Wang
- Laboratory of Cancer Epigenetics, Wuxi School of Medicine, Jiangnan University, Wuxi, China.,Wuxi Cancer Institute, Affiliated Hospital of Jiangnan University, Wuxi, 214062, Jiangsu, China
| | - Qingfeng Pang
- Department of physiopathology, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu province, China
| | - Zhaohui Huang
- Laboratory of Cancer Epigenetics, Wuxi School of Medicine, Jiangnan University, Wuxi, China. .,Wuxi Cancer Institute, Affiliated Hospital of Jiangnan University, Wuxi, 214062, Jiangsu, China.
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Takahashi T, Nishida T, Baba H, Hatta H, Imura J, Sutoh M, Toyohara S, Hokao R, Watanabe S, Ogawa H, Uehara H, Tsuneyama K. Histopathological characteristics of glutamine synthetase-positive hepatic tumor lesions in a mouse model of spontaneous metabolic syndrome (TSOD mouse). Mol Clin Oncol 2016; 5:267-270. [PMID: 27446562 PMCID: PMC4950734 DOI: 10.3892/mco.2016.924] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 04/27/2016] [Indexed: 12/11/2022] Open
Abstract
We previously reported that Tsumura-Suzuki obese diabetic (TSOD) mice, a polygenic model of spontaneous type 2 diabetes, is a valuable model of hepatic carcinogenesis via non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). One of the characteristics of tumors in these mice is the diffuse expression of glutamine synthetase (GS), which is a diagnostic marker for hepatocellular carcinoma (HCC). In this study, we performed detailed histopathological examinations and found that GS expression was diffusely positive in >70% of the hepatic tumors from 15-month-old male TSOD mice. Translocation of β-catenin into nuclei with enhanced membranous expression also occurred in GS-positive tumors. Small lesions (<1 mm) in GS-positive cases exhibited dysplastic nodules, with severe nuclear atypia, whereas large lesions (>3 mm) bore the characteristics of human HCC, exhibiting nuclear and structural atypia with invasive growth. By contrast, the majority of GS-negative tumors were hepatocellular adenomas with advanced fatty change and low nuclear grade. In GS-negative tumors, loss of liver fatty acid-binding protein expression was observed. These results suggest that the histological characteristics of GS-positive hepatic tumors in TSOD mice resemble human HCC; thus, this model may be a useful tool in translational research targeting the NAFLD/NASH-HCC sequence.
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Affiliation(s)
- Tetsuyuki Takahashi
- Department of Pathology and Laboratory Medicine, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Tokushima 770-8503, Japan
| | - Takeshi Nishida
- Department of Diagnostic Pathology, Graduate School of Medical and Pharmaceutical Sciences, University of Toyama, Toyama, Toyama 930-0194, Japan
| | - Hayato Baba
- Department of Diagnostic Pathology, Graduate School of Medical and Pharmaceutical Sciences, University of Toyama, Toyama, Toyama 930-0194, Japan
| | - Hideki Hatta
- Department of Diagnostic Pathology, Graduate School of Medical and Pharmaceutical Sciences, University of Toyama, Toyama, Toyama 930-0194, Japan
| | - Johji Imura
- Department of Diagnostic Pathology, Graduate School of Medical and Pharmaceutical Sciences, University of Toyama, Toyama, Toyama 930-0194, Japan
| | - Mitsuko Sutoh
- Institute for Animal Reproduction, Kasumigaura, Ibaraki 300-0134, Japan
| | - Syunji Toyohara
- Institute for Animal Reproduction, Kasumigaura, Ibaraki 300-0134, Japan
| | - Ryoji Hokao
- Institute for Animal Reproduction, Kasumigaura, Ibaraki 300-0134, Japan
| | - Syunsuke Watanabe
- Department of Pathology and Laboratory Medicine, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Tokushima 770-8503, Japan
| | - Hirohisa Ogawa
- Department of Pathology and Laboratory Medicine, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Tokushima 770-8503, Japan
| | - Hisanori Uehara
- Department of Pathology and Laboratory Medicine, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Tokushima 770-8503, Japan
| | - Koichi Tsuneyama
- Department of Pathology and Laboratory Medicine, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Tokushima 770-8503, Japan
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Chikada H, Ito K, Yanagida A, Nakauchi H, Kamiya A. The basic helix-loop-helix transcription factor, Mist1, induces maturation of mouse fetal hepatoblasts. Sci Rep 2015; 5:14989. [PMID: 26456005 PMCID: PMC4601036 DOI: 10.1038/srep14989] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 09/07/2015] [Indexed: 12/14/2022] Open
Abstract
Hepatic stem/progenitor cells, hepatoblasts, have a high proliferative ability and can differentiate into mature hepatocytes and cholangiocytes. Therefore, these cells are considered to be useful for regenerative medicine and drug screening for liver diseases. However, it is problem that in vitro maturation of hepatoblasts is insufficient in the present culture system. In this study, a novel regulator to induce hepatic differentiation was identified and the molecular function of this factor was examined in embryonic day 13 hepatoblast culture with maturation factor, oncostatin M and extracellular matrices. Overexpression of the basic helix-loop-helix type transcription factor, Mist1, induced expression of mature hepatocytic markers such as carbamoyl-phosphate synthetase1 and several cytochrome P450 (CYP) genes in this culture system. In contrast, Mist1 suppressed expression of cholangiocytic markers such as Sox9, Sox17, Ck19, and Grhl2. CYP3A metabolic activity was significantly induced by Mist1 in this hepatoblast culture. In addition, Mist1 induced liver-enriched transcription factors, CCAAT/enhancer-binding protein α and Hepatocyte nuclear factor 1α, which are known to be involved in liver functions. These results suggest that Mist1 partially induces mature hepatocytic expression and function accompanied by the down-regulation of cholangiocytic markers.
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Affiliation(s)
- Hiromi Chikada
- Department of Molecular Life Sciences, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan
| | - Keiichi Ito
- Division of Stem Cell Therapy, Center for Stem Cell and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, 4-6-4 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
| | - Ayaka Yanagida
- Division of Stem Cell Therapy, Center for Stem Cell and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, 4-6-4 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
| | - Hiromitsu Nakauchi
- Division of Stem Cell Therapy, Center for Stem Cell and Regenerative Medicine, The Institute of Medical Science, The University of Tokyo, 4-6-4 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, 265 Campus Drive, Stanford, California 94305-5461, USA
| | - Akihide Kamiya
- Department of Molecular Life Sciences, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan
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Current Proceedings in the Molecular Dissection of Hepatocellular Adenomas: Review and Hands-on Guide for Diagnosis. Int J Mol Sci 2015; 16:20994-1007. [PMID: 26404250 PMCID: PMC4613237 DOI: 10.3390/ijms160920994] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 08/10/2015] [Accepted: 08/19/2015] [Indexed: 02/07/2023] Open
Abstract
Molecular dissection of hepatocellular adenomas has brought forward a diversity of well-defined entities. Their distinction is important for routine practice, since prognosis is tightly related to the individual subgroup. Very recent activity has generated new details on the molecular background of hepatocellular adenoma, which this article aims to integrate into the current concepts of taxonomy.
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Thomeer MG, E Bröker ME, de Lussanet Q, Biermann K, Dwarkasing RS, de Man R, Ijzermans JN, de Vries M. Genotype-phenotype correlations in hepatocellular adenoma: an update of MRI findings. Diagn Interv Radiol 2015; 20:193-9. [PMID: 24509184 DOI: 10.5152/dir.2013.13315] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hepatocellular adenoma (HCA) is a generally benign liver tumor with the potential for malignancy and bleeding. HCAs are categorized into four subtypes on the basis of genetic and pathological features: hepatocyte nuclear factor 1α-mutated HCA, β-catenin-mutated HCA, inflammatory HCA, and unclassified HCA. Magnetic resonance imaging (MRI) plays an important role in the diagnosis, subtype characterization, and detection of HCA complications; it is also used to differentiate HCA from focal nodular hyperplasia. In this review, we present an overview of the genetic abnormalities, oncogenesis, and typical and atypical MRI findings of specific subtypes of HCA using contrast-enhanced MRI with or without hepatobiliary contrast agents (gadobenate dimeglumine and gadoxetate disodium). We also discuss their different management implications after diagnosis.
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Affiliation(s)
- Maarten G Thomeer
- From the Departments of Radiology Medical Center Zuiderzee, Lelystad, the Netherlands.
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High glucose potentiates L-FABP mediated fibrate induction of PPARα in mouse hepatocytes. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:1412-25. [PMID: 23747828 DOI: 10.1016/j.bbalip.2013.05.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 05/17/2013] [Accepted: 05/30/2013] [Indexed: 01/22/2023]
Abstract
Although liver fatty acid binding protein (L-FABP) binds fibrates and PPARα in vitro and enhances fibrate induction of PPARα in transformed cells, the functional significance of these findings is unclear, especially in normal hepatocytes. Studies with cultured primary mouse hepatocytes show that: 1) At physiological (6mM) glucose, fibrates (bezafibrate, fenofibrate) only weakly activated PPARα transcription of genes in LCFA β-oxidation; 2) High (11-20mM) glucose, but not maltose (osmotic control), significantly potentiated fibrate-induction of mRNA of these and other PPARα target genes to increase LCFA β-oxidation. These effects were associated with fibrate-mediated redistribution of L-FABP into nuclei-an effect prolonged by high glucose-but not with increased de novo fatty acid synthesis from glucose; 3) Potentiation of bezafibrate action by high glucose required an intact L-FABP/PPARα signaling pathway as shown with L-FABP null, PPARα null, PPARα inhibitor-treated WT, or PPARα-specific fenofibrate-treated WT hepatocytes. High glucose alone in the absence of fibrate was ineffective. Thus, high glucose potentiation of PPARα occurred through FABP/PPARα rather than indirectly through other PPARs or glucose induced signaling pathways. These data indicated L-FABP's importance in fibrate-induction of hepatic PPARα LCFA β-oxidative genes, especially in the context of high glucose levels.
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Petrescu AD, Huang H, Martin GG, McIntosh AL, Storey SM, Landrock D, Kier AB, Schroeder F. Impact of L-FABP and glucose on polyunsaturated fatty acid induction of PPARα-regulated β-oxidative enzymes. Am J Physiol Gastrointest Liver Physiol 2013; 304:G241-56. [PMID: 23238934 PMCID: PMC3566512 DOI: 10.1152/ajpgi.00334.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Liver fatty acid binding protein (L-FABP) is the major soluble protein that binds very-long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) in hepatocytes. However, nothing is known about L-FABP's role in n-3 PUFA-mediated peroxisome proliferator activated receptor-α (PPARα) transcription of proteins involved in long-chain fatty acid (LCFA) β-oxidation. This issue was addressed in cultured primary hepatocytes from wild-type, L-FABP-null, and PPARα-null mice with these major findings: 1) PUFA-mediated increase in the expression of PPARα-regulated LCFA β-oxidative enzymes, LCFA/LCFA-CoA binding proteins (L-FABP, ACBP), and PPARα itself was L-FABP dependent; 2) PPARα transcription, robustly potentiated by high glucose but not maltose, a sugar not taken up, correlated with higher protein levels of these LCFA β-oxidative enzymes and with increased LCFA β-oxidation; and 3) high glucose altered the potency of n-3 relative to n-6 PUFA. This was not due to a direct effect of glucose on PPARα transcriptional activity nor indirectly through de novo fatty acid synthesis from glucose. Synergism was also not due to glucose impacting other signaling pathways, since it was observed only in hepatocytes expressing both L-FABP and PPARα. Ablation of L-FABP or PPARα as well as treatment with MK886 (PPARα inhibitor) abolished/reduced PUFA-mediated PPARα transcription of these genes, especially at high glucose. Finally, the PUFA-enhanced L-FABP distribution into nuclei with high glucose augmentation of the L-FABP/PPARα interaction reveals not only the importance of L-FABP for PUFA induction of PPARα target genes in fatty acid β-oxidation but also the significance of a high glucose enhancement effect in diabetes.
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Affiliation(s)
- Anca D. Petrescu
- 1Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, Texas; and
| | - Huan Huang
- 1Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, Texas; and
| | - Gregory G. Martin
- 1Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, Texas; and
| | - Avery L. McIntosh
- 1Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, Texas; and
| | - Stephen M. Storey
- 1Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, Texas; and
| | - Danilo Landrock
- 1Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, Texas; and
| | - Ann B. Kier
- 2Department of Pathobiology, Texas A&M University, TVMC, College Station, Texas
| | - Friedhelm Schroeder
- 1Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, Texas; and
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Tan X, Sun X, Li Q, Zhao Y, Zhong W, Sun X, Jia W, McClain CJ, Zhou Z. Leptin deficiency contributes to the pathogenesis of alcoholic fatty liver disease in mice. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:1279-86. [PMID: 22841822 DOI: 10.1016/j.ajpath.2012.06.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 05/29/2012] [Accepted: 06/11/2012] [Indexed: 02/06/2023]
Abstract
White adipose tissue (WAT) secretes adipokines, which critically regulate lipid metabolism. The present study investigated the effects of alcohol on adipokines and the mechanistic link between adipokine dysregulation and alcoholic fatty liver disease. Mice were fed alcohol for 2, 4, or 8 weeks to document changes in adipokines over time. Alcohol exposure reduced WAT mass and body weight in association with hepatic lipid accumulation. The plasma adiponectin concentration was increased at 2 weeks, but declined to normal at 4 and 8 weeks. Alcohol exposure suppressed leptin gene expression in WAT and reduced the plasma leptin concentration at all times measured. There is a highly positive correlation between plasma leptin concentration and WAT mass or body weight. To determine whether leptin deficiency mediates alcohol-induced hepatic lipid dyshomeostasis, mice were fed alcohol for 8 weeks with or without leptin administration for the last 2 weeks. Leptin administration normalized the plasma leptin concentration and reversed alcoholic fatty liver. Alcohol-perturbed genes involved in fatty acid β-oxidation, very low-density lipoprotein secretion, and transcriptional regulation were attenuated by leptin. Leptin also normalized alcohol-reduced phosphorylation levels of signal transducer Stat3 and adenosine monophosphate-activated protein kinase. These data demonstrated for the first time that leptin deficiency in association with WAT mass reduction contributes to the pathogenesis of alcoholic fatty liver disease.
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Affiliation(s)
- Xiaobing Tan
- Center for Translational Biomedical Research, University of North Carolina at Greensboro, North Carolina Research Campus, Kannapolis, North Carolina 28081, USA
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12
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Yan J, Gong Y, Wang G, Gong Y, Burczynski FJ. Regulation of liver fatty acid binding protein expression by clofibrate in hepatoma cells. Biochem Cell Biol 2010; 88:957-67. [DOI: 10.1139/o10-151] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Peroxisome proliferator-activated receptor (PPAR) agonists such as clofibrate are known to affect liver fatty acid binding protein (L-FABP) levels, which in turn influence hepatocellular oxidant status. The mechanism of clofibrate’s modulation of L-FABP levels is not clear. In this study we used clofibrate (PPARα agonist), MK886 (PPARα antagonist), and GW9662 (PPARγ antagonist) in determining the regulating mechanism of L-FABP expression and its antioxidant activity in CRL-1548 hepatoma cells. Antioxidant activity was assessed by determining intracellular reactive oxygen species (ROS) using dichlorofluorescein (DCF) fluorescence. The effect of clofibrate on cytosolic activity of the intracellular antioxidant enzymes was also assessed. RT-PCR and mRNA stability assay showed that clofibrate treatment enhanced L-FABP mRNA stability, which resulted in increased L-FABP levels. A nuclear run-off assay and RT-PCR measurements of L-FABP mRNA revealed that clofibrate increased the L-FABP gene transcription rate. The increased L-FABP was associated with reduced cytosolic ROS. Levels of superoxide dismutase, glutathione peroxidase, and catalase were not affected by clofibrate treatment. L-FABP siRNA knockdown studies showed that a reduction in L-FABP expression was associated with increased DCF fluorescence. We conclude that clofibrate enhanced L-FABP gene transcription and mRNA stability, thus affecting L-FABP expression and ultimately cellular antioxidant activity.
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Affiliation(s)
- Jing Yan
- Faculty of Pharmacy, University of Manitoba, Winnipeg, MB R3E 0T5, Canada
- Section of Hepatology, Department of Internal Medicine, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
- McColl–Lockwood Laboratory, Cannon Research Center, Charlotte, NC 28232-2861, USA
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Yuewen Gong
- Faculty of Pharmacy, University of Manitoba, Winnipeg, MB R3E 0T5, Canada
- Section of Hepatology, Department of Internal Medicine, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
- McColl–Lockwood Laboratory, Cannon Research Center, Charlotte, NC 28232-2861, USA
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Guqi Wang
- Faculty of Pharmacy, University of Manitoba, Winnipeg, MB R3E 0T5, Canada
- Section of Hepatology, Department of Internal Medicine, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
- McColl–Lockwood Laboratory, Cannon Research Center, Charlotte, NC 28232-2861, USA
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Yu Gong
- Faculty of Pharmacy, University of Manitoba, Winnipeg, MB R3E 0T5, Canada
- Section of Hepatology, Department of Internal Medicine, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
- McColl–Lockwood Laboratory, Cannon Research Center, Charlotte, NC 28232-2861, USA
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
| | - Frank J. Burczynski
- Faculty of Pharmacy, University of Manitoba, Winnipeg, MB R3E 0T5, Canada
- Section of Hepatology, Department of Internal Medicine, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
- McColl–Lockwood Laboratory, Cannon Research Center, Charlotte, NC 28232-2861, USA
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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13
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Bonzo JA, Patterson AD, Krausz KW, Gonzalez FJ. Metabolomics identifies novel Hnf1alpha-dependent physiological pathways in vivo. Mol Endocrinol 2010; 24:2343-55. [PMID: 20943816 DOI: 10.1210/me.2010-0130] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Mutations in the HNF1A gene cause maturity-onset diabetes of the young type 3, one of the most common genetic causes of non-insulin-dependent (type 2) diabetes mellitus. Although the whole-body Hnf1a-null mouse recapitulates the low insulin levels and high blood glucose observed in human maturity-onset diabetes of the young type 3 patients, these mice also suffer from Laron dwarfism and aminoaciduria, suggesting a role for hepatocyte nuclear factor 1α (Hnf1α) in pathophysiologies distinct from non-insulin-dependent (type 2) diabetes mellitus. In an effort to identify pathways associated with inactivation of Hnf1α, an ultraperformance liquid chromatography coupled to mass spectrometry-based metabolomics study was conducted on urine samples from wild-type and Hnf1a-null mice. An increase in phenylalanine metabolites is in agreement with the known regulation of the phenylalanine hydroxylase gene by Hnf1α. This metabolomic approach also identified urinary biomarkers for three tissue-specific dysfunctions previously unassociated with Hnf1α function. 1) Elevated indolelactate coupled to decreased xanthurenic acid also indicated defects in the indole and kynurenine pathways of tryptophan metabolism, respectively. 2) An increase in the neutral amino acid proline in the urine of Hnf1a-null mice correlated with loss of renal apical membrane transporters of the Slc6a family. 3) Further investigation into the mechanism of aldosterone increase revealed an overactive adrenal gland in Hnf1a-null mice possibly due to inhibition of negative feedback regulation. Although the phenotype of the Hnf1a-null mouse is complex, metabolomics has opened the door to investigation of several physiological systems in which Hnf1α may be a critical regulatory component.
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Affiliation(s)
- Jessica A Bonzo
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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14
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Jeannot E, Mellottee L, Bioulac-Sage P, Balabaud C, Scoazec JY, Tran Van Nhieu J, Bacq Y, Michalak S, Buob D, Laurent-Puig P, Rusyn I, Zucman-Rossi J. Spectrum of HNF1A somatic mutations in hepatocellular adenoma differs from that in patients with MODY3 and suggests genotoxic damage. Diabetes 2010; 59:1836-44. [PMID: 20393147 PMCID: PMC2889786 DOI: 10.2337/db09-1819] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVE Maturity onset diabetes of the young type 3 (MODY3) is a consequence of heterozygous germline mutation in HNF1A. A subtype of hepatocellular adenoma (HCA) is also caused by biallelic somatic HNF1A mutations (H-HCA), and rare HCA may be related to MODY3. To better understand a relationship between the development of MODY3 and HCA, we compared both germline and somatic spectra of HNF1A mutations. RESEARCH DESIGN AND METHODS We compared 151 somatic HNF1A mutations in HCA with 364 germline mutations described in MODY3. We searched for genotoxic and oxidative stress features in HCA and surrounding liver tissue. RESULTS A spectrum of HNF1A somatic mutations significantly differed from the germline changes in MODY3. In HCA, we identified a specific hot spot at codon 206, nonsense and frameshift mutations mainly in the NH(2)-terminal part, and almost all amino acid substitutions were restricted to the POU-H domain. The high frequency of G-to-T tranversions, predominantly found on the nontranscribed DNA strand, suggested a genotoxic mechanism. However, no features of oxidative stress were observed in the nontumor liver tissue. Finally, in a few MODY3 patients with HNF1A germline mutation leading to amino acid substitutions outside the POU-H domain, we identified a different subtype of HCA either with a gp130 and/or CTNNB1 activating mutation. CONCLUSIONS Germline HNF1A mutations could be associated with different molecular subtypes of HCA. H-HCA showed mutations profoundly inactivating hepatocyte nuclear factor-1alpha function; they are associated with a genotoxic signature suggesting a specific toxicant exposure that could be associated with genetic predisposition.
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Affiliation(s)
- Emmanuelle Jeannot
- Institut National de la Santé et de la Recherche Médicale, U674, Génomique Fonctionnelle des Tumeurs Solides; Université Paris Descartes, Paris, France
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Lucille Mellottee
- Institut National de la Santé et de la Recherche Médicale, U674, Génomique Fonctionnelle des Tumeurs Solides; Université Paris Descartes, Paris, France
| | - Paulette Bioulac-Sage
- Institut National de la Santé et de la Recherche Médicale, U889, Université Bordeaux 2, IFR66, Centre Hospitalier Universitaire Bordeaux, Hôpital Pellegrin, Bordeaux, France
| | - Charles Balabaud
- Institut National de la Santé et de la Recherche Médicale, U889, Université Bordeaux 2, IFR66, Centre Hospitalier Universitaire Bordeaux, Hôpital Pellegrin, Bordeaux, France
| | | | - Jeanne Tran Van Nhieu
- Assistance Publique-Hôpitaux de Paris, Pathology Department, Hôpital Henri Mondor, Créteil, France
| | - Yannick Bacq
- Hôpital Trousseau, Centre Hospitalier Régional et Universitaire de Tours, Tours, France
| | - Sophie Michalak
- Centre Hospitalier Universitaire, Pathology Department, Angers, France
| | - David Buob
- Pôle Pathologie, Centre de Biologie Pathologie, Centre Hospitalier Régional et Universitaire de Lille, Lille, France
| | | | - Pierre Laurent-Puig
- Institut National de la Santé et de la Recherche Médicale, U775; Université Paris Descartes, Paris, France
| | - Ivan Rusyn
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jessica Zucman-Rossi
- Institut National de la Santé et de la Recherche Médicale, U674, Génomique Fonctionnelle des Tumeurs Solides; Université Paris Descartes, Paris, France
- Corresponding author: Jessica Zucman-Rossi,
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15
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Servitja JM, Pignatelli M, Maestro MA, Cardalda C, Boj SF, Lozano J, Blanco E, Lafuente A, McCarthy MI, Sumoy L, Guigó R, Ferrer J. Hnf1alpha (MODY3) controls tissue-specific transcriptional programs and exerts opposed effects on cell growth in pancreatic islets and liver. Mol Cell Biol 2009; 29:2945-59. [PMID: 19289501 PMCID: PMC2682018 DOI: 10.1128/mcb.01389-08] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 10/29/2008] [Accepted: 03/02/2009] [Indexed: 01/08/2023] Open
Abstract
Heterozygous HNF1A mutations cause pancreatic-islet beta-cell dysfunction and monogenic diabetes (MODY3). Hnf1alpha is known to regulate numerous hepatic genes, yet knowledge of its function in pancreatic islets is more limited. We now show that Hnf1a deficiency in mice leads to highly tissue-specific changes in the expression of genes involved in key functions of both islets and liver. To gain insights into the mechanisms of tissue-specific Hnf1alpha regulation, we integrated expression studies of Hnf1a-deficient mice with identification of direct Hnf1alpha targets. We demonstrate that Hnf1alpha can bind in a tissue-selective manner to genes that are expressed only in liver or islets. We also show that Hnf1alpha is essential only for the transcription of a minor fraction of its direct-target genes. Even among genes that were expressed in both liver and islets, the subset of targets showing functional dependence on Hnf1alpha was highly tissue specific. This was partly explained by the compensatory occupancy by the paralog Hnf1beta at selected genes in Hnf1a-deficient liver. In keeping with these findings, the biological consequences of Hnf1a deficiency were markedly different in islets and liver. Notably, Hnf1a deficiency led to impaired large-T-antigen-induced growth and oncogenesis in beta cells yet enhanced proliferation in hepatocytes. Collectively, these findings show that Hnf1alpha governs broad, highly tissue-specific genetic programs in pancreatic islets and liver and reveal key consequences of Hnf1a deficiency relevant to the pathophysiology of monogenic diabetes.
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Affiliation(s)
- Joan-Marc Servitja
- Genomic Programming of Beta-Cells Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
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16
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Transcriptional regulation of human UGT1A1 gene expression through distal and proximal promoter motifs: implication of defects in the UGT1A1 gene promoter. Naunyn Schmiedebergs Arch Pharmacol 2008; 377:597-605. [PMID: 18172616 DOI: 10.1007/s00210-007-0226-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Accepted: 11/16/2007] [Indexed: 12/15/2022]
Abstract
Human UDP-glucuronosyltransferase (UGT)1A1 is a critical enzyme responsible for detoxification and metabolism of endogenous and exogenous lipophilic compounds, such as potentially neurotoxic bilirubin and the anticancer drug irinotecan SN-38, via conjugation with glucuronic acid. A 290-bp distal enhancer module, phenobarbital-responsive enhancer module of UGT1A1 (gtPBREM), fully accounts for constitutive androstane receptor (CAR)-, pregnane X receptor (PXR)-, glucocorticoid receptor (GR)-, and aryl hydrocarbon receptor (AhR)-mediated activation of the UGT1A1 gene. This study indicates that hepatocyte nuclear factor 1alpha (HNF1alpha) bound to the proximal promoter motif not only enhances the basal reporter activity of UGT1A1, including the distal (-3570/-3180) and proximal (-165/-1) regions, but also influences the transcriptional regulation of UGT1A1 by CAR, PXR, GR, and AhR to markedly enhance reporter activities. Moreover, we assessed the influence of the TA repeat polymorphism and gtPBREM T-3279G mutation on transcriptional activation of UGT1A1 by CAR, PXR, GR, and AhR. Transcriptional activation of the A(TA)(7)TAA mutant by CAR, the PXR activator rifampicin, the GR activator dexamethasone, and the AhR activator benzo[a]pyrene was more reduced than that of the T-3279G variant, and the activity of the UGT1A1 promoter with both T-3279G and A(TA)(7)TAA mutations was still lower. Thus, UGT1A1 gene promoter variations, including the TA repeat polymorphism and T-3279G gtPBREM, have important clinical implications.
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17
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Yang Q, Nagano T, Shah Y, Cheung C, Ito S, Gonzalez FJ. The PPAR alpha-humanized mouse: a model to investigate species differences in liver toxicity mediated by PPAR alpha. Toxicol Sci 2007; 101:132-9. [PMID: 17690133 PMCID: PMC2197159 DOI: 10.1093/toxsci/kfm206] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
To determine the impact of the species difference between rodents and humans in response to peroxisome proliferators (PPs) mediated by peroxisome proliferator-activated receptor (PPAR)alpha, PPAR alpha-humanized transgenic mice were generated using a P1 phage artificial chromosome (PAC) genomic clone bred onto a ppar alpha-null mouse background, designated hPPAR alpha PAC. In hPPAR alpha PAC mice, the human PPAR alpha gene is expressed in tissues with high fatty acid catabolism and induced upon fasting, similar to mouse PPAR alpha in wild-type (Wt) mice. Upon treatment with the PP fenofibrate, hPPAR alpha PAC mice exhibited responses similar to Wt mice, including peroxisome proliferation, lowering of serum triglycerides, and induction of PPAR alpha target genes encoding enzymes involved in fatty acid metabolism in liver, kidney, and heart, suggesting that human PPAR alpha (hPPAR alpha) functions in the same manner as mouse PPAR alpha in regulating fatty acid metabolism and lowering serum triglycerides. However, in contrast to Wt mice, treatment of hPPAR alpha PAC mice with fenofibrate did not cause significant hepatomegaly and hepatocyte proliferation, thus indicating that the mechanisms by which PPAR alpha affects lipid metabolism are distinct from the hepatocyte proliferation response, the latter of which is only induced by mouse PPAR alpha. In addition, a differential regulation of several genes, including the oncogenic let-7C miRNA by PPs, was observed between Wt and hPPAR alpha PAC mice that may contribute to the inherent difference between mouse and human PPAR alpha in activation of hepatocellular proliferation. The hPPAR alpha PAC mouse model provides an in vivo platform to investigate the species difference mediated by PPAR alpha and an ideal model for human risk assessment PPs exposure.
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Affiliation(s)
| | | | | | | | | | - Frank J. Gonzalez
- To whom correspondence should be addressed. Frank J. Gonzalez, Building 37, Room 3106, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892. Fax: (301) 496-8419. E-mail:
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18
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The PPAR alpha-humanized mouse: a model to investigate species differences in liver toxicity mediated by PPAR alpha. Toxicol Sci 2007. [PMID: 17690133 DOI: 10.1093toxsci/kfm206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
To determine the impact of the species difference between rodents and humans in response to peroxisome proliferators (PPs) mediated by peroxisome proliferator-activated receptor (PPAR)alpha, PPAR alpha-humanized transgenic mice were generated using a P1 phage artificial chromosome (PAC) genomic clone bred onto a ppar alpha-null mouse background, designated hPPAR alpha PAC. In hPPAR alpha PAC mice, the human PPAR alpha gene is expressed in tissues with high fatty acid catabolism and induced upon fasting, similar to mouse PPAR alpha in wild-type (Wt) mice. Upon treatment with the PP fenofibrate, hPPAR alpha PAC mice exhibited responses similar to Wt mice, including peroxisome proliferation, lowering of serum triglycerides, and induction of PPAR alpha target genes encoding enzymes involved in fatty acid metabolism in liver, kidney, and heart, suggesting that human PPAR alpha (hPPAR alpha) functions in the same manner as mouse PPAR alpha in regulating fatty acid metabolism and lowering serum triglycerides. However, in contrast to Wt mice, treatment of hPPAR alpha PAC mice with fenofibrate did not cause significant hepatomegaly and hepatocyte proliferation, thus indicating that the mechanisms by which PPAR alpha affects lipid metabolism are distinct from the hepatocyte proliferation response, the latter of which is only induced by mouse PPAR alpha. In addition, a differential regulation of several genes, including the oncogenic let-7C miRNA by PPs, was observed between Wt and hPPAR alpha PAC mice that may contribute to the inherent difference between mouse and human PPAR alpha in activation of hepatocellular proliferation. The hPPAR alpha PAC mouse model provides an in vivo platform to investigate the species difference mediated by PPAR alpha and an ideal model for human risk assessment PPs exposure.
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19
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Yang Q, Ito S, Gonzalez FJ. Hepatocyte-restricted constitutive activation of PPAR alpha induces hepatoproliferation but not hepatocarcinogenesis. Carcinogenesis 2007; 28:1171-7. [PMID: 17331954 PMCID: PMC1885989 DOI: 10.1093/carcin/bgm046] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Peroxisome proliferator-activated receptor alpha (PPARalpha) is responsible for peroxisome proliferator-induced pleiotropic responses, including the development of hepatocellular carcinoma in rodents. However, it remains to be determined whether activation of PPARalpha only in hepatocytes is sufficient to induce hepatocellular carcinomas. To address this issue, transgenic mice were generated that target constitutively activated PPARalpha specifically to hepatocytes. The transgenic mice exhibited various responses that mimic wild-type mice treated with peroxisome proliferators, including significantly decreased serum fatty acids and marked induction of PPARalpha target genes encoding fatty acid oxidation enzymes, suggesting that the transgene functions in the same manner as peroxisome proliferators to regulate fatty acid metabolism. However, the transgenic mice did not develop hepatocellular carcinomas, even though they exhibited peroxisome proliferation and hepatocyte proliferation, indicating that these events are not sufficient to induce liver cancer. In contrast to the transgenic mice, peroxisome proliferators activate proliferation of hepatic non-parenchymal cells (NPCs). Thus, activation of hepatic NPCs and/or associated molecular events is an important step in peroxisome proliferators-induced hepatocarcinogenesis.
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Affiliation(s)
- Qian Yang
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Shinji Ito
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Frank J. Gonzalez
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
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20
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Yang Q, Kurotani R, Yamada A, Kimura S, Gonzalez FJ. Peroxisome proliferator-activated receptor alpha activation during pregnancy severely impairs mammary lobuloalveolar development in mice. Endocrinology 2006; 147:4772-80. [PMID: 16857745 PMCID: PMC1570154 DOI: 10.1210/en.2006-0437] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
To identify the potential functions of peroxisome proliferator-activated receptor alpha (PPARalpha) in skin development, transgenic mice were generated to target constitutively activated PPARalpha (VP16PPARalpha) to the stratified epithelia by use of the keratin K5 promoter. In addition to marked alterations in epidermal development, the transgenic mice had a severe defect in lactation during pregnancy resulting in 100% pup mortality. In this study, the alteration of mammary gland development in these transgenic mice was investigated. The results showed that expression of the VP16PPARalpha transgene during pregnancy resulted in impaired development of lobuloalveoli, which is associated with reduced proliferation and increased apoptosis of mammary epithelia. Mammary epithelia from transgenic mice also showed a significant reduction in the expression of beta-catenin and a down-regulation of one of its target genes, cyclin D1, which is thought to be required for lobuloalveolar development. Furthermore, upon PPARalpha ligand treatment, similar effects on lobuloalveolar development were observed in wild-type mice, but not in PPARalpha-null mice. These findings suggest that PPARalpha activation has a marked influence in mammary lobuloalveolar development.
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Affiliation(s)
- Qian Yang
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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21
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Dudas J, Elmaouhoub A, Mansuroglu T, Batusic D, Tron K, Saile B, Papoutsi M, Pieler T, Wilting J, Ramadori G. Prospero-related homeobox 1 (Prox1) is a stable hepatocyte marker during liver development, injury and regeneration, and is absent from "oval cells". Histochem Cell Biol 2006; 126:549-62. [PMID: 16770575 DOI: 10.1007/s00418-006-0191-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2006] [Indexed: 10/24/2022]
Abstract
The aim of this study was to analyse the changes of Prospero-related homeobox 1 (Prox1) gene expression in rat liver under different experimental conditions of liver injury, regeneration and acute phase reaction, and to correlate it with that of markers for hepatoblasts, hepatocytes, cholangiocytes and oval cells. Gene expression was studied at RNA level by RT-PCR, and at protein level by immunohistochemistry. At embryonal stage of rat liver development (embryonal days (ED) 14-16) hepatoblasts were found to be Prox1(+)/Cytokeratin (CK) 19(+) and alpha-fetoprotein (AFP)(+), at this stage Prox1(-)/CK19(+)/AFP(-) small cells (early cholangiocytes?) were identified. In fetal liver (ED 18-22) hepatoblasts were Prox1(+)/CK19(-)/AFP(+). CK7(+) cholangiocytes were detected at this stage, and they were Prox1(-)/AFP(-). In the adult liver hepatocytes were Prox1(+)/CK19(-)/CK7(-)/AFP(-), cholangiocytes were CK19(+) and/or CK7(+) and AFP(-)/Prox1(-). In models of liver damage and regeneration Prox1 remained a stable marker of hepatocytes. After 2-acetyl-aminofluorene treatment with partial hepatectomy (AAF/PH) the amount of Prox1 specific transcripts was low in the liver, when CK19 and AFP gene expression was high, and at no time point AFP(+)/CK19(+ )"oval cells" were found to be Prox1(+). However, a few Prox1(+)/CK19(+) and a few Prox1(+)/CK7(+ )cells were identified in the liver of AAF/PH-animals, which may represent precursors of hepatocytes, or a precancerous state.
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Affiliation(s)
- Jozsef Dudas
- Department of Internal Medicine, Section of Gastroenterology and Endocrinology, Georg-August-University Göttingen, Robert-Koch-Strasse 40, 37075 Goettingen, Germany
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22
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Morimura K, Cheung C, Ward JM, Reddy JK, Gonzalez FJ. Differential susceptibility of mice humanized for peroxisome proliferator-activated receptor alpha to Wy-14,643-induced liver tumorigenesis. Carcinogenesis 2006; 27:1074-80. [PMID: 16377806 PMCID: PMC1447533 DOI: 10.1093/carcin/bgi329] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Peroxisome proliferators, such as lipid-lowering fibrate drugs, are agonists for the peroxisome proliferator-activated receptor alpha (PPARalpha). Sustained activation of PPARalpha leads to the development of liver tumors in rodents. Paradoxically, humans appear to be resistant to the induction of peroxisome proliferation and development of liver tumors by peroxisome proliferators. To examine the species differences in response to peroxisome proliferators, a PPARalpha humanized mouse (hPPARalpha) was generated, in which the human PPARalpha was expressed in liver under control of the Tet-OFF system. To evaluate the susceptibility of hPPARalpha mice to peroxisome proliferator-induced hepatocarcinogenesis, a long-term feeding study of Wy-14,643 was carried out. hPPARalpha and wild-type (mPPARalpha) mice were fed either a control diet or one containing 0.1% Wy-14,643 for 44 and 38 weeks, respectively. Gene expression analysis for peroxisomal and mitochondrial fatty acid metabolizing enzymes revealed that both hPPARalpha and mPPARalpha were functional. However, the incidence of liver tumors including hepatocellular carcinoma was 71% in Wy-14,643-treated mPPARalpha mice, and 5% in Wy-14,643-treated hPPARalpha mice. Upregulation of cell cycle regulated genes such as cd1 and Cdks were observed in non-tumorous liver tissue of Wy-14,643-treated mPPARalpha mice, whereas p53 gene expression was increased only in the livers of Wy-14,643-treated hPPARalpha mice. These findings suggest that structural differences between human and mouse PPARalpha are responsible for the differential susceptibility to the peroxisome proliferator-induced hepatocarcinogenesis. This mouse model will be useful for human cancer risk assessment of PPARalpha ligands.
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Key Words
- pparα, peroxisome proliferator-activated receptor α
- wy-14,643, [4-chloro-6-(2,3-xylidino)-pyrimidynylthio]acetic acid
- 36b4, acidic ribosomal phosphoprotein
- acox, acyl-coa oxidase
- cyp4a, cytochrome p450 4a family
- mcad, medium chain acyl-coa dehydrogenase
- me, malic enzyme
- c myc, c-myc
- cd1, cyclin d1
- cdk, cyclin-dependent kinase
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Affiliation(s)
- Keiichirou Morimura
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Connie Cheung
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
| | - Jerrold M. Ward
- Comparative Medicine Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD
| | - Janardan K. Reddy
- Department of Pathology, Northwestern University School of Medicine, Chicago, IL
| | - Frank J. Gonzalez
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD
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Bosse T, van Wering HM, Gielen M, Dowling LN, Fialkovich JJ, Piaseckyj CM, Gonzalez FJ, Akiyama TE, Montgomery RK, Grand RJ, Krasinski SD. Hepatocyte nuclear factor-1alpha is required for expression but dispensable for histone acetylation of the lactase-phlorizin hydrolase gene in vivo. Am J Physiol Gastrointest Liver Physiol 2006; 290:G1016-24. [PMID: 16223943 DOI: 10.1152/ajpgi.00359.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hepatocyte nuclear factor-1alpha (HNF-1alpha) is a modified homeodomain-containing transcription factor that has been implicated in the regulation of intestinal genes. To define the importance and underlying mechanism of HNF-1alpha for the regulation of intestinal gene expression in vivo, we analyzed the expression of the intestinal differentiation markers and putative HNF-1alpha targets lactase-phlorizin hydrolase (LPH) and sucrase-isomaltase (SI) in hnf1alpha null mice. We found that in adult jejunum, LPH mRNA in hnf1alpha(-/-) mice was reduced 95% compared with wild-type controls (P < 0.01, n = 4), whereas SI mRNA was virtually identical to that in wild-type mice. Furthermore, SI mRNA abundance was unchanged in the absence of HNF-1alpha along the length of the adult mouse small intestine as well as in newborn jejunum. We found that HNF-1alpha occupies the promoters of both the LPH and SI genes in vivo. However, in contrast to liver and pancreas, where HNF-1alpha regulates target genes by recruitment of histone acetyl transferase activity to the promoter, the histone acetylation state of the LPH and SI promoters was not affected by the presence or absence of HNF-1alpha. Finally, we showed that a subset of hypothesized intestinal target genes is regulated by HNF-1alpha in vivo and that this regulation occurs in a defined tissue-specific and developmental context. These data indicate that HNF-1alpha is an activator of a subset of intestinal genes and induces these genes through an alternative mechanism in which it is dispensable for chromatin remodeling.
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Affiliation(s)
- Tjalling Bosse
- Department of Medicine, University of Amsterdam, Amsterdam, the Netherlands
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24
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Rowley CW, Staloch LJ, Divine JK, McCaul SP, Simon TC. Mechanisms of mutual functional interactions between HNF-4alpha and HNF-1alpha revealed by mutations that cause maturity onset diabetes of the young. Am J Physiol Gastrointest Liver Physiol 2006; 290:G466-75. [PMID: 16223942 DOI: 10.1152/ajpgi.00431.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hepatic nuclear factor (HNF)-4alpha and HNF-1alpha are key endodermal transcriptional regulators that physically and functionally interact. HNF-4alpha and HNF-1alpha cooperatively activate genes with binding sites for both factors, whereas suppressive interactions occur at regulatory sequences with a binding site for only one factor. The liver fatty acid binding protein gene (Fabp1) has binding sites for both factors, and chromatin precipitation assays were utilized to demonstrate that HNF-4alpha increased HNF-1alpha Fabp1 promoter occupancy during cooperative transcriptional activation. The HNF4 P2 promoter contains a HNF-1 but not HNF-4 binding site, and HNF-4alpha suppressed HNF-1alpha HNF4 P2 activation and decreased promoter HNF-1alpha occupancy. The apolipoprotein C III (APOC3) promoter contains a HNF-4 but not HNF-1 binding site, and HNF-1alpha suppressed HNF-4alpha APOC3 activation and decreased HNF-4alpha promoter occupancy. Maturity onset diabetes of the young (MODY) as well as defects in hepatic lipid metabolism result from mutations in either HNF-4alpha or HNF-1alpha. We found that MODY missense mutant R127W HNF-4alpha retained wild-type individual Fabp1 activation and bound to HNF-1alpha better than wild-type HNF-4alpha, yet did not cooperate with HNF-1alpha or increase HNF-1alpha Fabp1 promoter occupancy. The R127W mutant was also defective in both suppressing HNF-1alpha activation of HNF4 P2 and decreasing HNF-1alpha promoter occupancy. The HNF-1alpha R131Q MODY mutant also retained wild-type Fabp1 activation and bound to HNF-4alpha as well as the wild type but was defective in both suppressing HNF-4alpha APOC3 activation and decreasing HNF-4alpha promoter occupancy. These results suggest HNF-1alpha-HNF-4alpha functional interactions are accomplished by regulating factor promoter occupancy and that defective factor-factor interactions may contribute to the MODY phenotype.
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Affiliation(s)
- Christopher W Rowley
- Department of Pediatrics, Washington University School of Medicine, Campus Box 8208, St. Louis, MO 63110, USA
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25
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Anderson AL, Banks KE, Pontoglio M, Yaniv M, McLachlan A. Alpha/beta interferon differentially modulates the clearance of cytoplasmic encapsidated replication intermediates and nuclear covalently closed circular hepatitis B virus (HBV) DNA from the livers of hepatocyte nuclear factor 1alpha-null HBV transgenic mice. J Virol 2005; 79:11045-52. [PMID: 16103155 PMCID: PMC1193586 DOI: 10.1128/jvi.79.17.11045-11052.2005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Treatment with alpha interferon is a standard therapy for patients with chronic hepatitis B virus (HBV) infections. This treatment can reduce virus load and ameliorate disease symptoms. However, in the majority of cases, alpha interferon therapy fails to resolve the chronic HBV infection. The reason alpha interferon therapy is inefficient at resolving chronic HBV infections is assumed to be because it fails to eliminate covalently closed circular (CCC) HBV DNA from the nuclei of infected hepatocytes. In an attempt to address this issue, the stability of HBV CCC DNA in response to alpha/beta interferon induction was examined in HNF1alpha-null HBV transgenic mice. Alpha/beta interferon induction by polyinosinic-polycytidylic acid [poly(I-C)] treatment efficiently eliminated encapsidated cytoplasmic HBV replication intermediates while only modestly reducing nuclear HBV CCC DNA. These observations indicate that nuclear HBV CCC DNA is more stable than cytoplasmic replication intermediates in response to alpha/beta interferon induction. Consequently it appears that for therapies to resolve chronic HBV infection efficiently, they will have to target the elimination of the most stable HBV replication intermediate, nuclear HBV CCC DNA.
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Affiliation(s)
- Aimee L Anderson
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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26
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Divine JK, Staloch LJ, Haveri H, Jacobsen CM, Wilson DB, Heikinheimo M, Simon TC. GATA-4, GATA-5, and GATA-6 activate the rat liver fatty acid binding protein gene in concert with HNF-1alpha. Am J Physiol Gastrointest Liver Physiol 2004; 287:G1086-99. [PMID: 14715527 DOI: 10.1152/ajpgi.00421.2003] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Transcriptional regulation by GATA-4, GATA-5, and GATA-6 in intestine and liver was explored using a transgene constructed from the proximal promoter of the rat liver fatty acid binding protein gene (Fabpl). An immunohistochemical survey detected GATA-4 and GATA-6 in enterocytes, GATA-6 in hepatocytes, and GATA-5 in neither cell type in adult animals. In cell transfection assays, GATA-4 or GATA-5 but not GATA-6 activated the Fabpl transgene solely through the most proximal of three GATA binding sites in the Fabpl promoter. However, all three factors activated transgenes constructed from each Fabpl site upstream of a minimal viral promoter. GATA factors interact with hepatic nuclear factor (HNF)-1alpha, and the proximal Fabpl GATA site adjoins an HNF-1 site. GATA-4, GATA-5, or GATA-6 bounded to HNF-1alpha in solution, and all cooperated with HNF-1alpha to activate the Fabpl transgene. Mutagenizing all Fabpl GATA sites abrogated transgene activation by GATA factors, but GATA-4 activated the mutagenized transgene in the presence of HNF-1alpha. These in vitro results suggested GATA/HNF-1alpha interactions function in Fabpl regulation, and in vivo relevance was determined with subsequent experiments. In mice, the Fabpl transgene was active in enterocytes and hepatocytes, a transgene with mutagenized HNF-1 site was silent, and a transgene with mutagenized GATA sites had identical expression as the native transgene. Mice mosaic for biallelic Gata4 inactivation lost intestinal but not hepatic Fabpl expression in Gata4-deficient cells but not wild-type cells. These results demonstrate GATA-4 is critical for intestinal gene expression in vivo and suggest a specific GATA-4/HNF-1alpha physical and functional interaction in Fabpl activation.
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Affiliation(s)
- Joyce K Divine
- Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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27
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Kamijo A, Sugaya T, Hikawa A, Okada M, Okumura F, Yamanouchi M, Honda A, Okabe M, Fujino T, Hirata Y, Omata M, Kaneko R, Fujii H, Fukamizu A, Kimura K. Urinary excretion of fatty acid-binding protein reflects stress overload on the proximal tubules. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 165:1243-55. [PMID: 15466390 PMCID: PMC1618632 DOI: 10.1016/s0002-9440(10)63384-6] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Urinary excretion of human liver-type fatty acid-binding protein (hL-FABP), which is expressed in human proximal tubules and engaged in free fatty acid (FFA) metabolism, was reported to reflect the clinical prognosis of chronic kidney disease. Here we have investigated the pathophysiological significance of hL-FABP in a model of protein overload nephropathy. Because L-FABP is not expressed in the wild-type mice, we generated hL-FABP chromosomal gene transgenic (Tg) mice. Tg mice were intraperitoneally injected with bovine serum albumin (BSA) replete with FFAs (r-BSA group) or FFA-depleted BSA (d-BSA group). The r-BSA group developed significantly more severe tubulointerstitial damage than did the d-BSA group. Renal expression of the hL-FABP gene was more up-regulated, and urinary excretion of hL-FABP was significantly higher, in the r-BSA group than in the d-BSA group. Furthermore, compared with their wild-type littermates injected with r-BSA, the number of infiltrated macrophages was significantly attenuated in Tg mice injected with it on day 28. In patients with kidney disease (n = 50), urinary hL-FABP was correlated with both urinary protein and the severity of tubulointerstitial injury. In conclusion, our experimental model suggests that urinary excretion of hL-FABP reflects stresses, such as urinary protein overload, on the proximal tubules. The clinical observations support this hypothesis.
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Affiliation(s)
- Atsuko Kamijo
- St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-Ku, Kawasaki 216-8511, Japan
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28
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Yadetie F, Laegreid A, Bakke I, Kusnierczyk W, Komorowski J, Waldum HL, Sandvik AK. Liver gene expression in rats in response to the peroxisome proliferator-activated receptor-alpha agonist ciprofibrate. Physiol Genomics 2003; 15:9-19. [PMID: 12851464 DOI: 10.1152/physiolgenomics.00064.2003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Fibrate class hypolipidemic drugs such as ciprofibrate activate the peroxisome proliferator-activated receptor-alpha (PPARalpha), which is involved in processes including lipid metabolism and hepatocyte proliferation in rodents. We examined the effects of ciprofibrate (50 mg/kg body wt per day for 60 days) on liver gene expression in rats using cDNA microarrays. The 60-day dosing period was chosen to elucidate both the metabolic and proliferative actions of this substance, while avoiding confounding effects from the hepatic carcinogenesis seen during more long-term stimulation. Ciprofibrate changed the expression of many genes including previously known PPARalpha agonist-responsive genes involved in processes such as lipid metabolism and inflammatory responses. In addition, many novel candidate genes involved in sugar metabolism, transcription, signal transduction, cell proliferation, and stress responses appeared to be differentially regulated in ciprofibrate-dosed rats. Ciprofibrate also resulted in significant increases in liver weight and hepatocyte proliferation. The cDNA microarray results were confirmed by Northern blot analysis for selected genes. This study thus identifies many genes that appear to be differentially regulated in ciprofibrate-dosed rats, and some of these are potential targets of PPARalpha. The functional diversity of these candidate genes suggests that most of them are likely to be differentially regulated as indirect consequence of the many processes affected by ciprofibrate in rodent liver. Although caution is advisable in the interpretation of genome-wide expression data, the genes identified in the present study provide candidates for further studies that may give new insight into the mechanisms of action of peroxisome proliferators.
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Affiliation(s)
- Fekadu Yadetie
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, N-7489 Trondheim, Norway.
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29
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Fujishiro K, Fukui Y, Sato O, Kawabe K, Seto K, Motojima K. Analysis of tissue-specific and PPARalpha-dependent induction of FABP gene expression in the mouse liver by an in vivo DNA electroporation method. Mol Cell Biochem 2003. [PMID: 12479582 DOI: 10.1023/a: 1020546606429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Peroxisome proliferator (PPAR)alpha ligand Wy14,643 induces liver-fatty acid binding protein (FABP) spontaneously and heart-FABP gradually, but not intestine-FABP mRNA expression in the mouse liver. These strict regulations have not been reproduced in cultured cell systems. We applied a DNA electroporation method to directly introduce reporter gene constructs into the livers of mice. This system reproduced the in vivo responses of the above three FABP gene promoters to the PPARalpha ligand but not that of a promoter containing the typical three PPAR binding sites in tandem. Deletion and mutation analyses of the mouse L-FABP gene suggested that, in addition to the binding site for PPARalpha, a far upstream sequence is required for PPAR-dependent transactivation in the liver. In contrast to the cultured cell systems, our in vivo DNA electroporation method showed that PPARalpha binding to the promoter is necessary but not sufficient for PPARalpha ligand-dependent transcriptional activation of the L-FABP gene in vivo.
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Affiliation(s)
- Kensei Fujishiro
- Department of Biochemistry, School of Pharmaceutical Sciences, Toho University, Funabashi, Chiba, Japan
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30
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Divine JK, McCaul SP, Simon TC. HNF-1alpha and endodermal transcription factors cooperatively activate Fabpl: MODY3 mutations abrogate cooperativity. Am J Physiol Gastrointest Liver Physiol 2003; 285:G62-72. [PMID: 12646418 DOI: 10.1152/ajpgi.00074.2003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hepatocyte nuclear factor (HNF)-1alpha plays a central role in intestinal and hepatic gene regulation and is required for hepatic expression of the liver fatty acid binding protein gene (Fabpl). An Fabpl transgene was directly activated through cognate sites by HNF-1alpha and HNF-1beta, as well as five other endodermal factors: CDX-1, C/EBPbeta, GATA-4, FoxA2, and HNF-4alpha. HNF-1alpha activated the Fabpl transgene by as much as 60-fold greater in the presence of the other five endodermal factors than in their absence, accounting for up to one-half the total transgene activation by the group of six factors. This degree of synergistic interaction suggests that multifactor cooperativity is a critical determinant of endodermal gene activation by HNF-1alpha. Mutations in HNF-1alpha that result in maturity onset diabetes of the young (MODY3) provide evidence for the in vivo significance of these synergistic interactions. An R131Q HNF-1alpha MODY3 mutant exhibits complete loss of synergistic activation in concert with the other endodermal transcription factors despite wild-type transactivation ability in their absence. Furthermore, whereas wild-type HNF-1alpha exhibited pairwise cooperative synergy with each of the other five factors, the R131Q mutant could synergize only with GATA-4 and C/EBPbeta. Selective loss of synergy with other endodermal transcription factors accompanied by retention of native transactivation ability in an HNF-1alpha MODY mutant suggests in vivo significance for cooperative synergy.
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Affiliation(s)
- Joyce K Divine
- Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
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31
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Hayhurst GP, Lee YH, Lambert G, Ward JM, Gonzalez FJ. Hepatocyte nuclear factor 4alpha (nuclear receptor 2A1) is essential for maintenance of hepatic gene expression and lipid homeostasis. Mol Cell Biol 2001; 21:1393-403. [PMID: 11158324 PMCID: PMC99591 DOI: 10.1128/mcb.21.4.1393-1403.2001] [Citation(s) in RCA: 865] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The numerous functions of the liver are controlled primarily at the transcriptional level by the concerted actions of a limited number of hepatocyte-enriched transcription factors (hepatocyte nuclear factor 1alpha [HNF1alpha], -1beta, -3alpha, -3beta, -3gamma, -4alpha, and -6 and members of the c/ebp family). Of these, only HNF4alpha (nuclear receptor 2A1) and HNF1alpha appear to be correlated with the differentiated phenotype of cultured hepatoma cells. HNF1alpha-null mice are viable, indicating that this factor is not an absolute requirement for the formation of an active hepatic parenchyma. In contrast, HNF4alpha-null mice die during embryogenesis. Moreover, recent in vitro experiments using tetraploid aggregation suggest that HNF4alpha is indispensable for hepatocyte differentiation. However, the function of HNF4alpha in the maintenance of hepatocyte differentiation and function is less well understood. To address the function of HNF4alpha in the mature hepatocyte, a conditional gene knockout was produced using the Cre-loxP system. Mice lacking hepatic HNF4alpha expression accumulated lipid in the liver and exhibited greatly reduced serum cholesterol and triglyceride levels and increased serum bile acid concentrations. The observed phenotypes may be explained by (i) a selective disruption of very-low-density lipoprotein secretion due to decreased expression of genes encoding apolipoprotein B and microsomal triglyceride transfer protein, (ii) an increase in hepatic cholesterol uptake due to increased expression of the major high-density lipoprotein receptor, scavenger receptor BI, and (iii) a decrease in bile acid uptake to the liver due to down-regulation of the major basolateral bile acid transporters sodium taurocholate cotransporter protein and organic anion transporter protein 1. These data indicate that HNF4alpha is central to the maintenance of hepatocyte differentiation and is a major in vivo regulator of genes involved in the control of lipid homeostasis.
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Affiliation(s)
- G P Hayhurst
- Laboratory of Metabolism, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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