1
|
Bioinformatic analysis of microRNA networks following the activation of the constitutive androstane receptor (CAR) in mouse liver. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1228-1237. [PMID: 27080131 DOI: 10.1016/j.bbagrm.2016.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/01/2016] [Accepted: 04/03/2016] [Indexed: 12/18/2022]
Abstract
The constitutive androstane receptor (CAR; NR1I3) is a member of the nuclear receptor superfamily that functions as a xenosensor, serving to regulate xenobiotic detoxification, lipid homeostasis and energy metabolism. CAR activation is also a key contributor to the development of chemical hepatocarcinogenesis in mice. The underlying pathways affected by CAR in these processes are complex and not fully elucidated. MicroRNAs (miRNAs) have emerged as critical modulators of gene expression and appear to impact many cellular pathways, including those involved in chemical detoxification and liver tumor development. In this study, we used deep sequencing approaches with an Illumina HiSeq platform to differentially profile microRNA expression patterns in livers from wild type C57BL/6J mice following CAR activation with the mouse CAR-specific ligand activator, 1,4-bis-[2-(3,5,-dichloropyridyloxy)] benzene (TCPOBOP). Bioinformatic analyses and pathway evaluations were performed leading to the identification of 51 miRNAs whose expression levels were significantly altered by TCPOBOP treatment, including mmu-miR-802-5p and miR-485-3p. Ingenuity Pathway Analysis of the differentially expressed microRNAs revealed altered effector pathways, including those involved in liver cell growth and proliferation. A functional network among CAR targeted genes and the affected microRNAs was constructed to illustrate how CAR modulation of microRNA expression may potentially mediate its biological role in mouse hepatocyte proliferation. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie.
Collapse
|
2
|
Structural insights into gene repression by the orphan nuclear receptor SHP. Proc Natl Acad Sci U S A 2013; 111:839-44. [PMID: 24379397 DOI: 10.1073/pnas.1322827111] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Small heterodimer partner (SHP) is an orphan nuclear receptor that functions as a transcriptional repressor to regulate bile acid and cholesterol homeostasis. Although the precise mechanism whereby SHP represses transcription is not known, E1A-like inhibitor of differentiation (EID1) was isolated as a SHP-interacting protein and implicated in SHP repression. Here we present the crystal structure of SHP in complex with EID1, which reveals an unexpected EID1-binding site on SHP. Unlike the classical cofactor-binding site near the C-terminal helix H12, the EID1-binding site is located at the N terminus of the receptor, where EID1 mimics helix H1 of the nuclear receptor ligand-binding domain. The residues composing the SHP-EID1 interface are highly conserved. Their mutation diminishes SHP-EID1 interactions and affects SHP repressor activity. Together, these results provide important structural insights into SHP cofactor recruitment and repressor function and reveal a conserved protein interface that is likely to have broad implications for transcriptional repression by orphan nuclear receptors.
Collapse
|
3
|
Laurenzana EM, Chen T, Kannuswamy M, Sell BE, Strom SC, Li Y, Omiecinski CJ. The orphan nuclear receptor DAX-1 functions as a potent corepressor of the constitutive androstane receptor (NR1I3). Mol Pharmacol 2012; 82:918-28. [PMID: 22896671 DOI: 10.1124/mol.112.080721] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Regulation of gene transcription is controlled in part by nuclear receptors that function coordinately with coregulator proteins. The human constitutive androstane receptor (CAR; NR1I3) is expressed primarily in liver and regulates the expression of genes involved in xenobiotic metabolism as well as hormone, energy, and lipid homeostasis. In this report, DAX-1, a nuclear receptor family member with corepressor properties, was identified as a potent CAR regulator. Results of transaction and mutational studies demonstrated that both DAX-1's downstream LXXLL and its PCFQVLP motifs were critical contributors to DAX-1's corepression activities, although two other LXXM/LL motifs located nearer the N terminus had no impact on the CAR functional interaction. Deletion of DAX-1's C-terminal transcription silencing domain restored CAR1 transactivation activity in reporter assays to approximately 90% of control, demonstrating its critical function in mediating the CAR repression activities. Furthermore, results obtained from mammalian two-hybrid experiments assessing various domain configurations of the respective receptors showed that full-length DAX-1 inhibited the CAR-SRC1 interaction by approximately 50%, whereas the same interaction was restored to 90% of control when the DAX-1 transcription silencing domain was deleted. Direct interaction between CAR and DAX-1 was demonstrated with both alpha-screen and coimmunoprecipitation experiments, and this interaction was enhanced in the presence of the CAR activator 6-(4-chlorophenyl)imidazo[2,1-b]thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime (CITCO). Results obtained in primary human hepatocytes further demonstrated DAX-1 inhibition of CAR-mediated CITCO induction of the CYP2B6 target gene. The results of this investigation identify DAX-1 as a novel and potent CAR corepressor and suggest that DAX-1 functions as a coordinate hepatic regulator of CAR's biological function.
Collapse
Affiliation(s)
- Elizabeth M Laurenzana
- Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | | | | | | | | | | | | |
Collapse
|
4
|
Kim DK, Ryu D, Koh M, Lee MW, Lim D, Kim MJ, Kim YH, Cho WJ, Lee CH, Park SB, Koo SH, Choi HS. Orphan nuclear receptor estrogen-related receptor γ (ERRγ) is key regulator of hepatic gluconeogenesis. J Biol Chem 2012; 287:21628-39. [PMID: 22549789 DOI: 10.1074/jbc.m111.315168] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Glucose homeostasis is tightly controlled by hormonal regulation of hepatic glucose production. Dysregulation of this system is often associated with insulin resistance and diabetes, resulting in hyperglycemia in mammals. Here, we show that the orphan nuclear receptor estrogen-related receptor γ (ERRγ) is a novel downstream mediator of glucagon action in hepatic gluconeogenesis and demonstrate a beneficial impact of the inverse agonist GSK5182. Hepatic ERRγ expression was increased by fasting-dependent activation of the cAMP-response element-binding protein-CRTC2 pathway. Overexpression of ERRγ induced Pck1 and G6PC gene expression and glucose production in primary hepatocytes, whereas abolition of ERRγ gene expression attenuated forskolin-mediated induction of gluconeogenic gene expression. Deletion and mutation analyses of the Pck1 promoter showed that ERRγ directly regulates the Pck1 gene transcription via ERR response elements of the Pck1 promoter as confirmed by ChIP assay and in vivo imaging analysis. We also demonstrate that GSK5182, an inverse agonist of ERRγ, specifically inhibits the transcriptional activity of ERRγ in a PGC-1α dependent manner. Finally, the ERRγ inverse agonist ameliorated hyperglycemia through inhibition of hepatic gluconeogenesis in db/db mice. Control of hepatic glucose production by an ERRγ-specific inverse agonist is a new potential therapeutic approach for the treatment of type 2 diabetes.
Collapse
Affiliation(s)
- Don-Kyu Kim
- National Creative Research Initiatives Center for Nuclear Receptor Signals, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
A pleiotropic role for the orphan nuclear receptor small heterodimer partner in lipid homeostasis and metabolic pathways. J Lipids 2012; 2012:304292. [PMID: 22577560 PMCID: PMC3346990 DOI: 10.1155/2012/304292] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 12/05/2011] [Indexed: 12/29/2022] Open
Abstract
Nuclear receptors (NRs) comprise one of the most abundant classes of transcriptional regulators of metabolic diseases and have emerged as promising pharmaceutical targets. Small heterodimer partner (SHP; NR0B2) is a unique orphan NR lacking a DNA-binding domain but contains a putative ligand-binding domain. SHP is a transcriptional regulator affecting multiple key biological functions and metabolic processes including cholesterol, bile acid, and fatty acid metabolism, as well as reproductive biology and glucose-energy homeostasis. About half of all mammalian NRs and several transcriptional coregulators can interact with SHP. The SHP-mediated repression of target transcription factors includes at least three mechanisms including direct interference with the C-terminal activation function 2 (AF2) coactivator domains of NRs, recruitment of corepressors, or direct interaction with the surface of NR/transcription factors. Future research must focus on synthetic ligands acting on SHP as a potential therapeutic target in a series of metabolic abnormalities. Current understanding about the pleiotropic role of SHP is examined in this paper, and principal metabolic aspects connected with SHP function will be also discussed.
Collapse
|
6
|
Kim DK, Kim JR, Koh M, Kim YD, Lee JM, Chanda D, Park SB, Min JJ, Lee CH, Park TS, Choi HS. Estrogen-related receptor γ (ERRγ) is a novel transcriptional regulator of phosphatidic acid phosphatase, LIPIN1, and inhibits hepatic insulin signaling. J Biol Chem 2011; 286:38035-38042. [PMID: 21911493 DOI: 10.1074/jbc.m111.250613] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
LIPINs have been reported to perform important roles in the regulation of intracellular lipid levels. Their mutations induce lipodystrophy, myoglobinuria, and inflammatory disorders. Recently, the phosphatidic acid phosphatase function of LIPINs has been associated with the perturbation of hepatic insulin receptor signaling via the diacylglycerol-mediated stimulation of PKCε activity. Here, we report that nuclear estrogen-related receptor (ERR) γ is a novel transcriptional regulator of LIPIN1. Overexpression of ERRγ significantly increased LIPIN1 expression in primary hepatocytes, whereas the abolition of ERRγ gene expression attenuated the expression of LIPIN1. Deletion and mutation analyses of the LIPIN1 promoter showed that ERRγ exerts its effect on the transcriptional regulation of LIPIN1 via ERRE1 of the LIPIN1 promoter, as confirmed by ChIP assay. We also determined that the gene transcription of LIPIN1 by ERRγ is controlled by the competition between PGC-1α and small heterodimer partner. Additionally, ERRγ leads to the induction of hepatic LIPIN1 expression and diacylglycerol production in vivo. Finally, an inverse agonist of ERRγ, GSK5182, restores the impaired insulin signaling induced by LIPIN1-mediated PKCε activation. Our findings indicate that the selective control of ERRγ transcriptional activity by its specific inverse agonist could provide a novel therapeutic approach to the amelioration of impaired hepatic insulin signaling induced by LIPIN1-mediated PKCε activation.
Collapse
Affiliation(s)
- Don-Kyu Kim
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Jung Ran Kim
- Lee Gil Ya Cancer and Diabetes Institute, Department of Medicine, Gachon University of Medicine and Science, Incheon 406-840, Republic of Korea
| | - Minseob Koh
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-747, Republic of Korea
| | - Yong Deuk Kim
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Ji-Min Lee
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Dipanjan Chanda
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Seung Bum Park
- Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-747, Republic of Korea; Department of Biophysics and Chemical Biology, College of Natural Sciences, Seoul National University, Seoul 151-747, Republic of Korea
| | - Jung-Joon Min
- Departments of Nuclear Medicine and Microbiology, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea; Bioimaging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea
| | - Chul-Ho Lee
- Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Republic of Korea
| | - Tae-Sik Park
- Lee Gil Ya Cancer and Diabetes Institute, Department of Medicine, Gachon University of Medicine and Science, Incheon 406-840, Republic of Korea
| | - Hueng-Sik Choi
- National Creative Research Initiatives Center for Nuclear Receptor Signals and Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea; Research Institute of Medical Sciences, Department of Biomedical Sciences, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea.
| |
Collapse
|
7
|
Zhang Y, Hagedorn CH, Wang L. Role of nuclear receptor SHP in metabolism and cancer. Biochim Biophys Acta Mol Basis Dis 2010; 1812:893-908. [PMID: 20970497 DOI: 10.1016/j.bbadis.2010.10.006] [Citation(s) in RCA: 185] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 10/12/2010] [Accepted: 10/14/2010] [Indexed: 02/07/2023]
Abstract
Small heterodimer partner (SHP, NR0B2) is a unique member of the nuclear receptor (NR) superfamily that contains the dimerization and ligand-binding domain found in other family members, but lacks the conserved DNA-binding domain. The ability of SHP to bind directly to multiple NRs is crucial for its physiological function as a transcriptional inhibitor of gene expression. A wide variety of interacting partners for SHP have been identified, indicating the potential for SHP to regulate an array of genes in different biological pathways. In this review, we summarize studies concerning the structure and target genes of SHP and discuss recent progress in understanding the function of SHP in bile acid, cholesterol, triglyceride, glucose, and drug metabolism. In addition, we review the regulatory role of SHP in microRNA (miRNA) regulation, liver fibrosis and cancer progression. The fact that SHP controls a complex set of genes in multiple metabolic pathways suggests the intriguing possibility of developing new therapeutics for metabolic diseases, including fatty liver, dyslipidemia and obesity, by regulating SHP with small molecules. To achieve this goal, more progress regarding SHP ligands and protein structure will be required. Besides its metabolic regulatory function, studies by us and other groups provide strong evidence that SHP plays a critical role in the development of cancer, particularly liver and breast cancer. An increased understanding of the fundamental mechanisms by which SHP regulates the development of cancers will be critical in applying knowledge of SHP in diagnostic, therapeutic or preventive strategies for specific cancers. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease.
Collapse
Affiliation(s)
- Yuxia Zhang
- Department of Medicine, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | | | | |
Collapse
|
8
|
Chanda D, Xie YB, Choi HS. Transcriptional corepressor SHP recruits SIRT1 histone deacetylase to inhibit LRH-1 transactivation. Nucleic Acids Res 2010; 38:4607-19. [PMID: 20375098 PMCID: PMC2919721 DOI: 10.1093/nar/gkq227] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Orphan nuclear receptor Small Heterodimer Partner (SHP; NR0B2) is a transcriptional corepressor of a wide variety of nuclear receptors (NRs). Here, we report that SHP recruits SIRT1, a class III histone deacetylase, in an NR-specific manner to inhibit transcriptional activity. SHP interacts and co-localizes specifically with SIRT1 in vivo and inhibition of SIRT1 activity leads to a recovery from the intrinsic repressive activity of SHP but not of DAX1. Furthermore, we observed that SIRT1 does not deacetylate SHP or LRH1. However, inhibition of either SIRT1 or SHP significantly diminished the repressive effect of SHP on LRH1 transactivity. LRH1-mediated activation of CYP7A1 and SHP gene transcription was significantly repressed by both SHP and SIRT1 whereas inhibition of SIRT1 activity by inhibitors or dominant negative SIRT1 or knockdown of SHP led to a significant release of this inhibitory effect. ChIP assays revealed that SHP recruits SIRT1 on LRH1 target gene promoters and SIRT1 deacetylated template-dependent histone H3 and H4 to inhibit transcription of LRH1 target genes. Finally, we demonstrated that inhibition of SIRT1 activity significantly reversed SHP-mediated inhibition of bile-acid synthesis by LRH1 overexpression, thereby suggesting a novel mechanism of SHP-mediated inhibition of LRH1-dependent bile-acid homeostasis via recruitment of SIRT1 histone deacetylase protein.
Collapse
Affiliation(s)
- Dipanjan Chanda
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | | | | |
Collapse
|
9
|
Lam IPY, Lee LTO, Choi HS, Alpini G, Chow BKC. Bile acids inhibit duodenal secretin expression via orphan nuclear receptor small heterodimer partner (SHP). Am J Physiol Gastrointest Liver Physiol 2009; 297:G90-7. [PMID: 19372104 PMCID: PMC2711755 DOI: 10.1152/ajpgi.00094.2009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Small heterodimer partner (SHP) is an orphan nuclear receptor in which gene expression can be upregulated by bile acids. It regulates its target genes by repressing the transcriptional activities of other nuclear receptors including NeuroD, which has been shown to regulate secretin gene expression. Here, we evaluated the regulation on duodenal secretin gene expression by SHP and selected bile acids, cholic acid (CA) and chenodeoxycholic acid (CDCA). In vitro treatment of CDCA or fexaramine elevated the SHP transcript level and occupancy on secretin promoter. The increase in the SHP level, induced by bile acid treatment or overexpression, reduced secretin gene expression, whereas this gene inhibitory effect was reversed by silencing of endogenous SHP. In in vivo studies, double-immunofluorescence staining demonstrated the coexpression of secretin and SHP in mouse duodenum. Feeding mice with 1% CA-enriched rodent chow resulted in upregulation of SHP and a concomitant decrease in secretin transcript and protein levels in duodenum compared with the control group fed with normal chow. A diet enriched with 5% cholestyramine led to a decrease in SHP level and a corresponding increase in secretin expression. Overall, this study showed that bile acids via SHP inhibit duodenal secretin gene expression. Because secretin is a key hormone that stimulates bile flow in cholangiocytes, this pathway thus provides a novel means to modulate secretin-stimulated choleresis in response to intraduodenal bile acids.
Collapse
Affiliation(s)
- Ian P. Y. Lam
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China; Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea; Research, Central Texas Veterans Health Care System, Medicine and Systems Biology and Translational Medicine, Texas A & M Health Science Center, College of Medicine, Temple, Texas
| | - Leo T. O. Lee
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China; Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea; Research, Central Texas Veterans Health Care System, Medicine and Systems Biology and Translational Medicine, Texas A & M Health Science Center, College of Medicine, Temple, Texas
| | - Hueng-Sik Choi
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China; Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea; Research, Central Texas Veterans Health Care System, Medicine and Systems Biology and Translational Medicine, Texas A & M Health Science Center, College of Medicine, Temple, Texas
| | - Gianfranco Alpini
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China; Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea; Research, Central Texas Veterans Health Care System, Medicine and Systems Biology and Translational Medicine, Texas A & M Health Science Center, College of Medicine, Temple, Texas
| | - Billy K. C. Chow
- School of Biological Sciences, The University of Hong Kong, Hong Kong, China; Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea; Research, Central Texas Veterans Health Care System, Medicine and Systems Biology and Translational Medicine, Texas A & M Health Science Center, College of Medicine, Temple, Texas
| |
Collapse
|
10
|
Xie YB, Nedumaran B, Choi HS. Molecular characterization of SMILE as a novel corepressor of nuclear receptors. Nucleic Acids Res 2009; 37:4100-15. [PMID: 19429690 PMCID: PMC2709580 DOI: 10.1093/nar/gkp333] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
SMILE (small heterodimer partner interacting leucine zipper protein) has been identified as a coregulator in ER signaling. In this study, we have examined the effects of SMILE on other NRs (nuclear receptors). SMILE inhibits GR, CAR and HNF4α-mediated transactivation. Knockdown of SMILE gene expression increases the transactivation of the NRs. SMILE interacts with GR, CAR and HNF4α in vitro and in vivo. SMILE and these NRs colocalize in the nucleus. SMILE binds to the ligand-binding domain or AF2 domain of the NRs. Competitions between SMILE and the coactivators GRIP1 or PGC-1α have been demonstrated in vitro and in vivo. Furthermore, an intrinsic repressive activity of SMILE is observed in Gal4-fusion system, and the intrinsic repressive domain is mapped to the C-terminus of SMILE, spanning residues 203–354. Moreover, SMILE interacts with specific HDACs (histone deacetylases) and SMILE-mediated repression is released by HDAC inhibitor trichostatin A, in a NR-specific manner. Finally, ChIP (chromatin immunoprecipitation) assays reveal that SMILE associates with the NRs on the target gene promoters. Adenoviral overexpression of SMILE represses GR-, CAR- and HNF4α-mediated target gene expression. Overall, these results suggest that SMILE functions as a novel corepressor of NRs via competition with coactivators and the recruitment of HDACs.
Collapse
Affiliation(s)
- Yuan-Bin Xie
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, 500-757, Republic of Korea
| | | | | |
Collapse
|
11
|
Sablin EP, Woods A, Krylova IN, Hwang P, Ingraham HA, Fletterick RJ. The structure of corepressor Dax-1 bound to its target nuclear receptor LRH-1. Proc Natl Acad Sci U S A 2008; 105:18390-5. [PMID: 19015525 PMCID: PMC2587556 DOI: 10.1073/pnas.0808936105] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Indexed: 11/18/2022] Open
Abstract
The Dax-1 protein is an enigmatic nuclear receptor that lacks an expected DNA binding domain, yet functions as a potent corepressor of nuclear receptors. Here we report the structure of Dax-1 bound to one of its targets, liver receptor homolog 1 (LRH-1). Unexpectedly, Dax-1 binds to LRH-1 using a new module, a repressor helix built from a family conserved sequence motif, PCFXXLP. Mutations in this repressor helix that are linked with human endocrine disorders dissociate the complex and attenuate Dax-1 function. The structure of the Dax-1:LRH-1 complex provides the molecular mechanism for the function of Dax-1 as a potent transcriptional repressor.
Collapse
Affiliation(s)
| | - April Woods
- Departments of Biochemistry and Biophysics and
| | - Irina N. Krylova
- Molecular and Cellular Pharmacology, University of California, San Francisco, CA 94143
| | - Peter Hwang
- Departments of Biochemistry and Biophysics and
| | - Holly A. Ingraham
- Molecular and Cellular Pharmacology, University of California, San Francisco, CA 94143
| | | |
Collapse
|
12
|
Orphan nuclear receptor SHP interacts with and represses hepatocyte nuclear factor-6 (HNF-6) transactivation. Biochem J 2008; 413:559-69. [PMID: 18459945 DOI: 10.1042/bj20071637] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
SHP (small heterodimer partner; NR0B2) is an atypical orphan NR (nuclear receptor) that functions as a transcriptional co-repressor by interacting with a diverse set of NRs and transcriptional factors. HNF-6 (hepatocyte nuclear factor-6) is a key regulatory factor in pancreatic development, endocrine differentiation and the formation of the biliary tract, as well as glucose metabolism. In this study, we have investigated the function of SHP as a putative repressor of HNF-6. Using transient transfection assays, we have shown that SHP represses the transcriptional activity of HNF-6. Confocal microscopy revealed that both SHP and HNF-6 co-localize in the nuclei of cells. SHP physically interacted with HNF-6 in protein-protein association assays in vitro. EMSAs (electrophoretic mobility-shift assays) and ChIP (chromatin immunoprecipitation) assays demonstrated that SHP inhibits the DNA-binding activity of HNF-6 to an HNF-6-response element consensus sequence, and the HNF-6 target region of the endogenous G6Pase (glucose 6-phosphatase) promoter respectively. Northern blot analysis of HNF-6 target genes in cells infected with adenoviral vectors for SHP and SHP siRNAs (small inhibitory RNAs) indicated that SHP represses the expression of endogenous G6Pase and PEPCK (phosphoenolpyruvate carboxykinase). Our results suggest that HNF-6 is a novel target of SHP in the regulation of gluconeogenesis.
Collapse
|
13
|
Dawson MI, Xia Z, Jiang T, Ye M, Fontana JA, Farhana L, Patel B, Xue LP, Bhuiyan M, Pellicciari R, Macchiarulo A, Nuti R, Zhang XK, Han YH, Tautz L, Hobbs PD, Jong L, Waleh N, Chao WR, Feng GS, Pang Y, Su Y. Adamantyl-substituted retinoid-derived molecules that interact with the orphan nuclear receptor small heterodimer partner: effects of replacing the 1-adamantyl or hydroxyl group on inhibition of cancer cell growth, induction of cancer cell apoptosis, and inhibition of SRC homology 2 domain-containing protein tyrosine phosphatase-2 activity. J Med Chem 2008; 51:5650-62. [PMID: 18759424 DOI: 10.1021/jm800456k] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
(E)-4-[3-(1-Adamantyl)-4'-hydroxyphenyl]-3-chlorocinnamic acid (3-Cl-AHPC) induces the cell-cycle arrest and apoptosis of leukemia and cancer cells. Studies demonstrated that 3-Cl-AHPC bound to the atypical orphan nuclear receptor small heterodimer partner (SHP). Although missing a DNA-binding domain, SHP heterodimerizes with the ligand-binding domains of other nuclear receptors to repress their abilities to induce or inhibit gene expression. 3-Cl-AHPC analogues having the 1-adamantyl and phenolic hydroxyl pharmacophoric elements replaced with isosteric groups were designed, synthesized, and evaluated for their inhibition of proliferation and induction of human cancer cell apoptosis. Structure-anticancer activity relationship studies indicated the importance of both groups to apoptotic activity. Docking of 3-Cl-AHPC and its analogues to an SHP computational model that was based on the crystal structure of ultraspiracle complexed with 1-stearoyl-2-palmitoylglycero-3-phosphoethanolamine suggested why these 3-Cl-AHPC groups could influence SHP activity. Inhibitory activity against Src homology 2 domain-containing protein tyrosine phosphatase 2 (Shp-2) was also assessed. The most active Shp-2 inhibitor was found to be the 3'-(3,3-dimethylbutynyl) analogue of 3-Cl-AHPC.
Collapse
Affiliation(s)
- Marcia I Dawson
- Cancer Center and Inflammatory and Infectious Disease Center, Burnham Institute for Medical Research, La Jolla, California 92037, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Chanda D, Park JH, Choi HS. Molecular basis of endocrine regulation by orphan nuclear receptor Small Heterodimer Partner. Endocr J 2008; 55:253-68. [PMID: 17984569 DOI: 10.1507/endocrj.k07e-103] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Nuclear receptors (NRs) are a unique superfamily of transcription factors (TFs) which are involved in and play a crucial role in almost all aspects of mammalian physiology. Small Heterodimer Partner (SHP; NR0B2), an exceptional member of this superfamily of NRs, have been identified as a key regulatory factor of the transcription of a variety of genes involved in diverse metabolic pathways, and are thereby an important factor in a variety of physiological functions. Since its discovery a decade ago, considerable progress has been made in the elucidation of the underlying mechanism by which SHP regulates various metabolic processes, and the results of previous studies support its importance in the maintenance of metabolic homeostasis. In this review, we have evaluated the current state of understanding of the molecular mechanisms and the resultant physiological interpretations governed by SHP.
Collapse
Affiliation(s)
- Dipanjan Chanda
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
| | | | | |
Collapse
|
15
|
Kim YD, Park KG, Lee YS, Park YY, Kim DK, Nedumaran B, Jang WG, Cho WJ, Ha J, Lee IK, Lee CH, Choi HS. Metformin inhibits hepatic gluconeogenesis through AMP-activated protein kinase-dependent regulation of the orphan nuclear receptor SHP. Diabetes 2008; 57:306-14. [PMID: 17909097 DOI: 10.2337/db07-0381] [Citation(s) in RCA: 313] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Metformin is an antidiabetic drug commonly used to treat type 2 diabetes. The aim of the study was to determine whether metformin regulates hepatic gluconeogenesis through the orphan nuclear receptor small heterodimer partner (SHP; NR0B2). RESEARCH DESIGN AND METHODS We assessed the regulation of hepatic SHP gene expression by Northern blot analysis with metformin and adenovirus containing a constitutive active form of AMP-activated protein kinase (AMPK) (Ad-AMPK) and evaluated SHP, PEPCK, and G6Pase promoter activities via transient transfection assays in hepatocytes. Knockdown of SHP using siRNA SHP was conducted to characterize the metformin-induced inhibition of hepatic gluconeogenic gene expression in hepatocytes, and metformin-and adenovirus SHP (Ad-SHP)-mediated hepatic glucose production was measured in B6-Lep(ob/ob) mice. RESULTS Hepatic SHP gene expression was induced by metformin, 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR), and Ad-AMPK. Metformin-induced SHP gene expression was abolished by adenovirus containing the dominant negative form of AMPK (Ad-DN-AMPK), as well as by compound C. Metformin inhibited hepatocyte nuclear factor-4alpha-or FoxA2-mediated promoter activity of PEPCK and G6Pase, and the inhibition was blocked with siRNA SHP. Additionally, SHP knockdown by adenovirus containing siRNA SHP inhibited metformin-mediated repression of cAMP/dexamethasone-induced hepatic gluconeogenic gene expression. Furthermore, oral administration of metformin increased SHP mRNA levels in B6-Lep(ob/ob) mice. Overexpression of SHP by Ad-SHP decreased blood glucose levels and hepatic gluconeogenic gene expression in B6-Lep(ob/ob) mice. CONCLUSIONS We have concluded that metformin inhibits hepatic gluconeogenesis through AMPK-dependent regulation of SHP.
Collapse
Affiliation(s)
- Yong Deuk Kim
- Hormone Research Center, School of Biological Sciences & Technology, Chonnam National University, Gwangju, 500-757, Republic of Korea
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Vargas D, Celis L, Romero C, Lizcano F. Modulation of thyroid hormone receptor transactivation by the early region 1A (E1A)-like inhibitor of differentiation 1 (EID1). Genet Mol Biol 2008. [DOI: 10.1590/s1415-47572008000300003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
17
|
Lee YS, Chanda D, Sim J, Park YY, Choi HS. Structure and function of the atypical orphan nuclear receptor small heterodimer partner. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 261:117-58. [PMID: 17560281 DOI: 10.1016/s0074-7696(07)61003-1] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The small heterodimer partner (SHP; NROB2) is a member of the nuclear receptor superfamily and is classified as an "orphan" subgroup, as its ligand has not yet been identified. SHP lacks the classical DNA-binding domain found in most nuclear receptors and functions as a transcriptional coregulator by directly interacting with nuclear receptors and other transcription factors. SHP regulates the transcription of a variety of target genes and controls a variety of physiological functions. For the past 10 years, great progress has been made in our understanding of the mechanism of action of SHP and the regulation of SHP gene expression. Many of the results imply that SHP has a variety of roles in the regulation of metabolic homeostasis. In this review, we discuss the current state of understanding of the structure, expression, and function of the orphan nuclear receptor, SHP.
Collapse
Affiliation(s)
- Yong-Soo Lee
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Korea
| | | | | | | | | |
Collapse
|
18
|
Suh JH, Huang J, Park YY, Seong HA, Kim D, Shong M, Ha H, Lee IK, Lee K, Wang L, Choi HS. Orphan nuclear receptor small heterodimer partner inhibits transforming growth factor-beta signaling by repressing SMAD3 transactivation. J Biol Chem 2006; 281:39169-78. [PMID: 17074765 DOI: 10.1074/jbc.m605947200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Orphan nuclear receptor small heterodimer partner (SHP) is an atypical member of the nuclear receptor superfamily; SHP regulates the nuclear receptor-mediated transcription of target genes but lacks a conventional DNA binding domain. In this study, we demonstrate that SHP represses transforming growth factor-beta (TGF-beta)-induced gene expression through a direct interaction with Smad, a transducer of TGF-beta signaling. Transient transfection studies demonstrate that SHP represses Smad3-induced transcription. In vivo and in vitro protein interaction assays revealed that SHP directly interacts with Smad2 and Smad3 but not with Smad4. Mapping of domains mediating the interaction between SHP and Smad3 showed that the entire N-terminal domain (1-159 amino acids) of SHP and the linker domain of Smad3 are involved in this interaction. In vitro glutathione S-transferase pulldown competition experiments revealed the SHP-mediated repression of Smad3 transactivation through competition with its co-activator p300. SHP also inhibits the activation of endogenous TGF-beta-responsive gene promoters, the p21, Smad7, and plasminogen activator inhibitor-1 (PAI-1) promoters. Moreover, adenovirus-mediated overexpression of SHP decreases PAI-1 mRNA levels, and down-regulation of SHP by a small interfering RNA increases both the transactivation of Smad3 and the PAI-1 mRNA levels. Finally, the PAI-1 gene is expressed in SHP(-/-) mouse hepatocytes at a higher level than in normal hepatocytes. Taken together, these data indicate that SHP is a novel co-regulator of Smad3, and this study provides new insights into regulation of TGF-beta signaling.
Collapse
Affiliation(s)
- Ji Ho Suh
- Hormone Research Center, School of Biological Science and Technology, Chonnam National University, Kwangju 500-757, Republic of Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Song KH, Park YY, Kee HJ, Hong CY, Lee YS, Ahn SW, Kim HJ, Lee K, Kook H, Lee IK, Choi HS. Orphan nuclear receptor Nur77 induces zinc finger protein GIOT-1 gene expression, and GIOT-1 acts as a novel corepressor of orphan nuclear receptor SF-1 via recruitment of HDAC2. J Biol Chem 2006; 281:15605-14. [PMID: 16595694 DOI: 10.1074/jbc.m505937200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Kruppel-associated box (KRAB) domain-containing proteins consist of potential transcriptional repression modules. Previously, gonadotropin-inducible ovarian transcription factor-1 (GIOT-1) was identified as a novel KRAB-containing zinc finger protein and shown to have transcriptional repression activity. Here, we demonstrate that orphan nuclear receptor Nur77 regulates GIOT-1 gene expression in testicular Leydig cell lines and that GIOT-1 acts as a novel corepressor of the orphan nuclear receptor steroidogenic factor 1 (SF-1). Mutation analysis of the GIOT-1 promoter and overexpression analysis of dominant-negative Nur77 revealed that luteinizing hormone activates GIOT-1 gene expression through Nur77. Electrophoretic mobility shift and chromatin immunoprecipitation assays showed that Nur77 directly binds to the GIOT-1 promoter. GIOT-1 represses the SF-1 transactivation, and specific interaction between GIOT-1 and SF-1 was observed. We also demonstrate an interaction between GIOT-1 and histone deacetylase 2 (HDAC2). GIOT-1-mediated transrepression was recovered by down-regulation of HDAC2 expression with small interfering RNA of HDAC2. Knock down of the endogenous GIOT-1 results in significant enhancement of CYP17 expression in Leydig cells. In conclusion, this study of cross-talk between GIOT-1 and orphan nuclear receptors will provide new insights into the role of KRAB-containing zinc finger proteins in nuclear receptor action.
Collapse
Affiliation(s)
- Kwang-Hoon Song
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Macchiarulo A, Rizzo G, Costantino G, Fiorucci S, Pellicciari R. Unveiling hidden features of orphan nuclear receptors: The case of the small heterodimer partner (SHP). J Mol Graph Model 2006; 24:362-72. [PMID: 16288980 DOI: 10.1016/j.jmgm.2005.09.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 09/29/2005] [Accepted: 09/29/2005] [Indexed: 10/25/2022]
Abstract
The small heterodimer partner (SHP) is an atypical nuclear receptor lacking the N-terminal ligand-independent activation domain and the DNA binding domain. SHP acts as transcriptional inhibitor of a large set of nuclear receptors, among which ER, AR, CAR, RXR, GR, LXR and ERRgamma. The repression mechanism of SHP involves several actions including competition with coactivators binding on the AF-2 of nuclear receptors and recruitment of transcriptional inhibitors such as EID-1. The investigation of the structure and repression mechanism of SHP is a challenging task for a full understanding of nuclear receptor interaction pathways and functions. So far, mutational analyses in multiple populations identified loss of function mutants of SHP gene involved in mild obesity, increased birth weight and insulin levels. Furthermore, experimental mutagenesis has been exploited to characterize the interactions between SHP and the transcriptional inhibitor EID-1. With the aim of gaining insight into the structural basis of SHP repression mechanism, we modelled SHP and EID-1 structures. Docking experiments were carried out to identify the EID-1 binding surface on SHP structure. The results obtained in this study allow for the first time a unique interpretation of many experimental data available from the published literature. In addition, a fascinating hypothesis raises from the inspection of the proposed SHP structure: the presence of a potential unexpected ligand binding site, supported by recently available experimental data that may represent a breakthrough in the design and development of synthetic modulators of SHP functions.
Collapse
Affiliation(s)
- Antonio Macchiarulo
- Dipartimento di Chimica e Tecnologia del Farmaco, Università di Perugia, via del Liceo 1, 06127 Perugia, Italy
| | | | | | | | | |
Collapse
|
21
|
Song KH, Chiang JYL. Glucagon and cAMP inhibit cholesterol 7alpha-hydroxylase (CYP7A1) gene expression in human hepatocytes: discordant regulation of bile acid synthesis and gluconeogenesis. Hepatology 2006; 43:117-25. [PMID: 16323215 DOI: 10.1002/hep.20919] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The gene encoding cholesterol 7alpha-hydroxylase (CYP7A1) is tightly regulated to control bile acid synthesis and maintain lipid homeostasis. Recent studies in mice suggest that bile acid synthesis is regulated by the fasted-to-fed cycle, and fasting induces CYP7A1 gene expression in parallel to the induction of peroxisome proliferators-activated receptor gamma co-activator 1alpha (PGC-1alpha) and phosphoenolpyruvate carboxykinase (PEPCK). How glucagon regulates CYP7A1 gene expression in the human liver is not clear. Here we show that glucagon and cyclic adenosine monophosphate (cAMP) strongly repressed CYP7A1 mRNA expression in human primary hepatocytes. Reporter assays confirmed that cAMP and protein kinase A (PKA) inhibited human CYP7A1 gene transcription, in contrast to their stimulation of the PEPCK gene. Mutagenesis analysis identified a PKA-responsive region located within the previously identified HNF4alpha binding site in the human CYP7A1 promoter. Glucagon and cAMP increased HNF4alpha phosphorylation and reduced the amount of HNF4alpha present in CYP7A1 chromatin. Our findings suggest that glucagon inhibited CYP7A1 gene expression via PKA phosphorylation of HNF4alpha, which lost its ability to bind the CYP7A1 gene and resulted in inhibition of human CYP7A1 gene transcription. In conclusion, this study unveils a species difference in nutrient regulation of the human and mouse CYP7A1 gene and suggests a discordant regulation of bile acid synthesis and gluconeogenesis by glucagon in human livers during fasting.
Collapse
Affiliation(s)
- Kwang-Hoon Song
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown, OH 44272, USA
| | | |
Collapse
|
22
|
Park YY, Ahn SW, Kim HJ, Kim JM, Lee IK, Kang H, Choi HS. An autoregulatory loop controlling orphan nuclear receptor DAX-1 gene expression by orphan nuclear receptor ERRgamma. Nucleic Acids Res 2005; 33:6756-68. [PMID: 16314306 PMCID: PMC1301593 DOI: 10.1093/nar/gki976] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The estrogen receptor-related receptor gamma (ERRγ/ERR3/NR3B3) is a member of the nuclear receptor superfamily that activates transcription in the absence of ligand. However, the detailed mechanism of gene regulation by ERRγ is not fully understood. In this study we have found that the orphan nuclear receptor ERRγ activates the DAX-1 promoter, which, in turn, represses transactivation by ERRγ. Serial deletions of mouse DAX-1 (mDAX-1) gene promoter have revealed that the region responding to ERRγ is located between −129 and −121 bp and −334 and −326 bp. Gel shift assays and chromatin immunoprecipitation (ChIP) assays demonstrated that ERRγ binds directly to the mDAX-1 promoter. Site-directed mutagenesis results demonstrated that ERRE1 (−129 to −121 bp) is more important than ERRE2 (−334 to −326 bp) which is not conserved in the human DAX-1 promoter. In addition, adenovirus-mediated overexpression of ERRγ induced DAX-1 gene expression in MCF-7 breast cancer cells that co-expressed ERRγ and DAX-1. Moreover, yeast two-hybrid and glutathione S-transferase (GST)-pull down assays demonstrated that DAX-1 physically interacted with ERRγ and inhibited ERRγ transactivation, and that this interaction was dependent on the AF-2 domain of ERRγ. In addition, in vitro competition assays showed that DAX-1 inhibited PGC-1α mediated ERRγ transactivation, via competition between these two factors for the AF-2 binding domain. We thus propose a novel autoregulatory loop that controls DAX-1 gene expression by ERRγ.
Collapse
Affiliation(s)
| | | | - Hye-Jin Kim
- Section of Endocrinology, Department of Internal Medicine, Kyungpook National University Hospital, School of Medicine, Kyungpook National UniversityTaegu, Republic of Korea
| | - Jin-Man Kim
- Department of Pathology, College of Medicine, Chungnam National UniversityDaejeon, 301-131, Republic of Korea
| | - In-Kyu Lee
- Section of Endocrinology, Department of Internal Medicine, Kyungpook National University Hospital, School of Medicine, Kyungpook National UniversityTaegu, Republic of Korea
| | - Heonjoong Kang
- Center for Marine Natural Products and Drug Discovery, School of Earth and Environmental Science, Seoul National UniversitySeoul, Republic of Korea
| | - Hueng-Sik Choi
- To whom correspondence should be addressed. Tel: +82 62 530 0503; Fax: +82 62 530 0500;
| |
Collapse
|
23
|
Sasajima Y, Tanaka H, Miyake S, Yuasa Y. A novel EID family member, EID-3, inhibits differentiation and forms a homodimer or heterodimer with EID-2. Biochem Biophys Res Commun 2005; 333:969-75. [PMID: 15970276 DOI: 10.1016/j.bbrc.2005.06.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Accepted: 06/06/2005] [Indexed: 11/23/2022]
Abstract
The EID family members, i.e., E1A-like inhibitor of differentiation-1 (EID-1) and EID-1-like inhibitor of differentiation-2 (EID-2), were identified as negative regulators of cellular differentiation. EID-1 seems to inhibit differentiation by blocking histone acetyltransferase activity and EID-2 possibly inhibits differentiation through binding to class I histone deacetylases (HDACs). Here, we report a novel inhibitor of differentiation exhibiting homology with EID-2 termed EID-3 (EID-2-like inhibitor of differentiation-3). Like EID-2, EID-3 inhibited MyoD- and GRalpha-dependent transcription and blocked muscle differentiation in cultured cells by binding to class I HDACs. Unlike that of EID-2, the C-terminus, but not the N-terminus, of EID-3 was required for nuclear localization. EID-3 formed a homodimer or heterodimer with EID-2. These results suggest that EID-3 inhibits differentiation by blocking transcription as a complex in cells.
Collapse
Affiliation(s)
- Yuka Sasajima
- Department of Molecular Oncology, Graduate School of Medicine and Dentistry, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | | | | | | |
Collapse
|
24
|
Yeo MG, Yoo YG, Choi HS, Pak YK, Lee MO. Negative cross-talk between Nur77 and small heterodimer partner and its role in apoptotic cell death of hepatoma cells. Mol Endocrinol 2004; 19:950-63. [PMID: 15625237 DOI: 10.1210/me.2004-0209] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Nur77, an orphan nuclear receptor, has been implicated in apoptosis of a variety of cell types, including hepatocytes. The small heterodimer partner (SHP) binds and inhibits the function of many nuclear receptors. Here, we investigated cross-talk between Nur77 and SHP during anti-Fas antibody (CH11)-mediated apoptosis of hepatic cells. Expression of SHP decreased, whereas antisense SHP enhanced, the transcriptional activity of Nur77 in HepG2 cells. SHP and Nur77 were physically associated in vivo and colocalized in the nucleus. SHP decreased the transactivation function of the N-terminal domain of Nur77 that recruits coactivators. Nur77 and SHP competitively bound to cAMP response element-binding protein-binding protein and the expression of coactivators, such as cAMP response element-binding protein-binding protein and activating signal cointegrator-2, recovered the decreased function of Nur77 caused by SHP. Finally, SHP was differentially expressed in hepatoma cell lines in that it was not detected in the interferon-gamma (IFNgamma)/CH11-sensitive SNU354, whereas it was significantly expressed in the IFNgamma/CH11-resistant HepG2. Interestingly, a stable SNU354 cell line that expressed SHP became resistant to the IFNgamma/CH11-induced apoptosis. Together, our results suggest that SHP plays a key role in the regulation of Nur77 activation and thereby in Nur77-mediated apoptosis in the liver.
Collapse
MESH Headings
- Apoptosis
- Binding, Competitive
- Carcinoma, Hepatocellular/metabolism
- Cell Nucleus/chemistry
- Cyclic AMP Response Element-Binding Protein/metabolism
- DNA-Binding Proteins/analysis
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Dimerization
- Down-Regulation
- Humans
- Intracellular Signaling Peptides and Proteins/metabolism
- Liver Neoplasms/metabolism
- Nuclear Receptor Coactivators
- Nuclear Receptor Subfamily 4, Group A, Member 1
- Protein Structure, Tertiary
- Receptors, Cytoplasmic and Nuclear/analysis
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Steroid/analysis
- Receptors, Steroid/genetics
- Receptors, Steroid/metabolism
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Transcription Factors/analysis
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcription, Genetic
- Transcriptional Activation
- Tumor Cells, Cultured
Collapse
Affiliation(s)
- Myeong Goo Yeo
- College of Pharmacy, Seoul National University, San 56-1 Sillim, Kwanak, Seoul 151-742, Korea
| | | | | | | | | |
Collapse
|
25
|
Kim JY, Kim HJ, Kim KT, Park YY, Seong HA, Park KC, Lee IK, Ha H, Shong M, Park SC, Choi HS. Orphan nuclear receptor small heterodimer partner represses hepatocyte nuclear factor 3/Foxa transactivation via inhibition of its DNA binding. Mol Endocrinol 2004; 18:2880-94. [PMID: 15358835 DOI: 10.1210/me.2004-0211] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Small heterodimer partner (SHP; NR0B2) is an atypical orphan nuclear receptor and acts as a coregulator of various nuclear receptors. Herein, we examined a novel cross talk between SHP and a forkhead transcription factor HNF3 (hepatocyte nuclear factor 3/Foxa. Transient transfection assay demonstrated that SHP inhibited the transcriptional activity of all three isoforms of HNF3, HNF3alpha, beta, and gamma. In vivo and in vitro protein interaction studies showed that SHP physically interacted with HNF3. Adenovirus-mediated overexpression of SHP significantly decreased the mRNA levels of glucose-6-phosphase (G6Pase), cholesterol 7-alpha-hydroxylase (CYP7A1), and phosphoenolpyruvate carboxykinase (PEPCK) in HepG2 cells and rat primary hepatocytes. Moreover, the mRNA level of G6Pase was notably increased by down-regulation of SHP with small interfering RNA. Interestingly, HNF3 transactivity was still repressed by SHPDelta128-139 that fails to repress nuclear receptors. Mapping of interaction domain revealed that SHP interacted with forkhead DNA binding domain of HNF3alpha. Gel mobility shift and chromatin immunoprecipitation assays demonstrated that SHP inhibits DNA binding of HNF3. These results suggest that SHP is involved in the regulation of G6Pase, CYP7A1, and PEPCK gene expression via novel mechanism of inhibition of HNF3 activity and expand the role of SHP as a coregulator of other family of transcription factors in addition to nuclear receptors.
Collapse
Affiliation(s)
- Joon-Young Kim
- Hormone Research Center, Chonnam National University, Gwangju 500-757, Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Iyer AK, McCabe ERB. Molecular mechanisms of DAX1 action. Mol Genet Metab 2004; 83:60-73. [PMID: 15464421 DOI: 10.1016/j.ymgme.2004.07.018] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Revised: 07/12/2004] [Accepted: 07/13/2004] [Indexed: 11/24/2022]
Abstract
DAX1 (dosage sensitive sex reversal (DSS), adrenal hypoplasia congenita (AHC) critical region on the X chromosome, gene 1) encoded by the gene NR0B1, is an unusual orphan nuclear receptor that when mutated causes AHC with associated hypogonadotropic hypogonadism (HH), and when duplicated causes DSS. DAX1 expression has been shown in all regions of the hypothalamic-pituitary-adrenal-gonadal (HPAG) axis during development and in adult tissues, suggesting a critical role for DAX1 in the normal development and function of this axis. Steroidogenic factor 1 (SF1, NR5A1) knockout mice show similar developmental defects as AHC and HH patients, but paradoxically, DAX1 is a negative coregulator of SF1 transactivation. The function of DAX1 as an antagonist of SF1 in gonadal development is consistent with the fact that in humans, duplication of the region of the X chromosome containing DAX1 causes a similar phenotype as mutations in SF1. However, how disruption of DAX1 leads to adrenal, hypothalamic, and pituitary developmental defects similar to SF1 disruption remains to be clarified. The exact mechanism of DAX1 action in each of these tissues during adulthood and critical stages of development are not fully understood. Recent evidence suggests a broader functional role for DAX1 as a negative coregulator of estrogen receptor (ER, NR3A1-2), liver receptor homologue-1 (LRH-1, NR5A2), androgen receptor (AR, NR3C4), and progesterone receptor (PR, NR3C3), each by distinct repression mechanisms. DAX1 may have pleiotropic roles in addition to its function as a negative regulator of steroidogenesis during the development and adult function of the HPAG axis.
Collapse
MESH Headings
- Animals
- DAX-1 Orphan Nuclear Receptor
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- DNA-Binding Proteins/physiology
- Female
- Gene Expression Regulation, Developmental
- Homeodomain Proteins
- Humans
- Hypothalamo-Hypophyseal System/physiology
- Male
- Mice
- Ovary/growth & development
- Ovary/physiology
- Pituitary-Adrenal System/physiology
- Receptors, Androgen/genetics
- Receptors, Androgen/metabolism
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Receptors, Progesterone/genetics
- Receptors, Progesterone/metabolism
- Receptors, Retinoic Acid/physiology
- Repressor Proteins/physiology
- Sex Determination Processes
- Steroidogenic Factor 1
- Testis/growth & development
- Testis/physiology
- Transcription Factors/genetics
- Transcription Factors/metabolism
Collapse
Affiliation(s)
- Anita K Iyer
- Department of Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | | |
Collapse
|