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Haque N, Tischkau SA. Sexual Dimorphism in Adipose-Hypothalamic Crosstalk and the Contribution of Aryl Hydrocarbon Receptor to Regulate Energy Homeostasis. Int J Mol Sci 2022; 23:ijms23147679. [PMID: 35887027 PMCID: PMC9322714 DOI: 10.3390/ijms23147679] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/08/2022] [Accepted: 07/09/2022] [Indexed: 11/16/2022] Open
Abstract
There are fundamental sex differences in the regulation of energy homeostasis. Better understanding of the underlying mechanisms of energy balance that account for this asymmetry will assist in developing sex-specific therapies for sexually dimorphic diseases such as obesity. Multiple organs, including the hypothalamus and adipose tissue, play vital roles in the regulation of energy homeostasis, which are regulated differently in males and females. Various neuronal populations, particularly within the hypothalamus, such as arcuate nucleus (ARC), can sense nutrient content of the body by the help of peripheral hormones such leptin, derived from adipocytes, to regulate energy homeostasis. This review summarizes how adipose tissue crosstalk with homeostatic network control systems in the brain, which includes energy regulatory regions and the hypothalamic–pituitary axis, contribute to energy regulation in a sex-specific manner. Moreover, development of obesity is contingent upon diet and environmental factors. Substances from diet and environmental contaminants can exert insidious effects on energy metabolism, acting peripherally through the aryl hydrocarbon receptor (AhR). Developmental AhR activation can impart permanent alterations of neuronal development that can manifest a number of sex-specific physiological changes, which sometimes become evident only in adulthood. AhR is currently being investigated as a potential target for treating obesity. The consensus is that impaired function of the receptor protects from obesity in mice. AhR also modulates sex steroid receptors, and hence, one of the objectives of this review is to explain why investigating sex differences while examining this receptor is crucial. Overall, this review summarizes sex differences in the regulation of energy homeostasis imparted by the adipose–hypothalamic axis and examines how this axis can be affected by xenobiotics that signal through AhR.
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Affiliation(s)
- Nazmul Haque
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62702, USA;
| | - Shelley A. Tischkau
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62702, USA;
- Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL 62702, USA
- Correspondence:
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2
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Nahalka J. Transcription of the Envelope Protein by 1-L Protein-RNA Recognition Code Leads to Genes/Proteins That Are Relevant to the SARS-CoV-2 Life Cycle and Pathogenesis. Curr Issues Mol Biol 2022; 44:791-816. [PMID: 35723340 PMCID: PMC8928949 DOI: 10.3390/cimb44020055] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 01/21/2022] [Accepted: 02/03/2022] [Indexed: 12/02/2022] Open
Abstract
The theoretical protein-RNA recognition code was used in this study to research the compatibility of the SARS-CoV-2 envelope protein (E) with mRNAs in the human transcriptome. According to a review of the literature, the spectrum of identified genes showed that the virus post-transcriptionally promotes or represses the genes involved in the SARS-CoV-2 life cycle. The identified genes/proteins are also involved in adaptive immunity, in the function of the cilia and wound healing (EMT and MET) in the pulmonary epithelial tissue, in Alzheimer's and Parkinson's disease and in type 2 diabetes. For example, the E-protein promotes BHLHE40, which switches off the IL-10 inflammatory "brake" and inhibits antiviral THαβ cells. In the viral cycle, E supports the COPII-SCAP-SREBP-HSP90α transport complex by the lowering of cholesterol in the ER and by the repression of insulin signaling, which explains the positive effect of HSP90 inhibitors in COVID-19 (geldanamycin), and E also supports importin α/β-mediated transport to the nucleus, which explains the positive effect of ivermectin, a blocker of importins α/β. In summary, transcription of the envelope protein by the 1-L protein-RNA recognition code leads to genes/proteins that are relevant to the SARS-CoV-2 life cycle and pathogenesis.
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Affiliation(s)
- Jozef Nahalka
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dubravska Cesta 9, SK-84538 Bratislava, Slovakia
- Centre of Excellence for White-Green Biotechnology, Institute of Chemistry, Slovak Academy of Sciences, Trieda Andreja Hlinku 2, SK-94976 Nitra, Slovakia
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Imai Y, Koseki Y, Hirano M, Nakamura S. Nutrigenomic Studies on the Ameliorative Effect of Enzyme-Digested Phycocyanin in Alzheimer's Disease Model Mice. Nutrients 2021; 13:nu13124431. [PMID: 34959983 PMCID: PMC8707209 DOI: 10.3390/nu13124431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/03/2021] [Accepted: 12/06/2021] [Indexed: 01/01/2023] Open
Abstract
Alzheimer’s disease (AD) is the most common form of dementia, and the cognitive impairments associated with this degenerative disease seriously affect daily life. Nutraceuticals for the prevention or delay of AD are urgently needed. It has been increasingly observed that phycocyanin (PC) exerts neuroprotective effects. AD model mice intracerebroventricularly injected with amyloid beta-peptide 25–35 (Aβ25–35) at 10 nmol/head displayed significant cognitive impairment in the spontaneous alternation test. Cognitive impairment was significantly ameliorated in mice treated with 750 mg/kg of enzyme-digested (ED) PC by daily oral administration for 22 consecutive days. Application of DNA microarray data on hippocampal gene expression to nutrigenomics studies revealed that oral EDPC counteracted the aberrant expression of 35 genes, including Prnp, Cct4, Vegfd (Figf), Map9 (Mtap9), Pik3cg, Zfand5, Endog, and Hbq1a. These results suggest that oral administration of EDPC ameliorated cognitive impairment in AD model mice by maintaining and/or restoring normal gene expression patterns in the hippocampus.
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Affiliation(s)
- Yasuyuki Imai
- Health Care Technical G., Chiba Plants, DIC Corporation, Ichihara 290-8585, Chiba, Japan; (Y.I.); (Y.K.)
| | - Yurino Koseki
- Health Care Technical G., Chiba Plants, DIC Corporation, Ichihara 290-8585, Chiba, Japan; (Y.I.); (Y.K.)
| | - Makoto Hirano
- R&D Institute, Intelligence & Technology Lab, Inc., Kaizu 503-0628, Gifu, Japan;
| | - Shin Nakamura
- R&D Institute, Intelligence & Technology Lab, Inc., Kaizu 503-0628, Gifu, Japan;
- Biomedical Institute, NPO Primate Agora, Kaizu 503-0628, Gifu, Japan
- Correspondence: ; Tel.: +81-(0)-584-54-0015
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Ellsworth BS, Stallings CE. Molecular Mechanisms Governing Embryonic Differentiation of Pituitary Somatotropes. Trends Endocrinol Metab 2018; 29:510-523. [PMID: 29759686 DOI: 10.1016/j.tem.2018.04.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 04/18/2018] [Accepted: 04/19/2018] [Indexed: 02/07/2023]
Abstract
Pituitary somatotropes secrete growth hormone (GH), which is essential for normal growth and metabolism. Somatotrope defects result in GH deficiency (GHD), leading to short stature in childhood and increased cardiovascular morbidity and mortality in adulthood. Current hormone replacement therapies fail to recapitulate normal pulsatile GH secretion. Stem cell therapies could overcome this problem but are dependent on a thorough understanding of somatotrope differentiation. Although several transcription factors, signaling pathways, and hormones that regulate this process have been identified, the mechanisms of action are not well understood. The purpose of this review is to highlight the known players in somatotrope differentiation while emphasizing the need to better understand these pathways to serve patients with GHD.
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Affiliation(s)
- Buffy S Ellsworth
- Department of Physiology, School of Medicine, Southern Illinois University, Carbondale, IL 62901-6523, USA.
| | - Caitlin E Stallings
- Department of Physiology, School of Medicine, Southern Illinois University, Carbondale, IL 62901-6523, USA
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Dunham LSS, Momiji H, Harper CV, Downton PJ, Hey K, McNamara A, Featherstone K, Spiller DG, Rand DA, Finkenstädt B, White MRH, Davis JRE. Asymmetry between Activation and Deactivation during a Transcriptional Pulse. Cell Syst 2017; 5:646-653.e5. [PMID: 29153839 PMCID: PMC5747351 DOI: 10.1016/j.cels.2017.10.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 08/04/2017] [Accepted: 10/18/2017] [Indexed: 11/23/2022]
Abstract
Transcription in eukaryotic cells occurs in gene-specific bursts or pulses of activity. Recent studies identified a spectrum of transcriptionally active “on-states,” interspersed with periods of inactivity, but these “off-states” and the process of transcriptional deactivation are poorly understood. To examine what occurs during deactivation, we investigate the dynamics of switching between variable rates. We measured live single-cell expression of luciferase reporters from human growth hormone or human prolactin promoters in a pituitary cell line. Subsequently, we applied a statistical variable-rate model of transcription, validated by single-molecule FISH, to estimate switching between transcriptional rates. Under the assumption that transcription can switch to any rate at any time, we found that transcriptional activation occurs predominantly as a single switch, whereas deactivation occurs with graded, stepwise decreases in transcription rate. Experimentally altering cAMP signalling with forskolin or chromatin remodelling with histone deacetylase inhibitor modifies the duration of defined transcriptional states. Our findings reveal transcriptional activation and deactivation as mechanistically independent, asymmetrical processes. Gene transcription switches between variable rates Single-cell microscopy and mathematical modeling quantifies switch dynamics We observe an asymmetry in the activation/deactivation of transcriptional bursts
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Affiliation(s)
- Lee S S Dunham
- Division of Endocrinology, Diabetes and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, AV Hill Building, Manchester M13 9PT, UK
| | - Hiroshi Momiji
- Warwick Systems Biology Centre, University of Warwick, Coventry CV4, 7AL, UK
| | - Claire V Harper
- Division of Cellular and Molecular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester M13 9PT, UK
| | - Polly J Downton
- Division of Cellular and Molecular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester M13 9PT, UK
| | - Kirsty Hey
- Department of Statistics, University of Warwick, Coventry CV4 7AL, UK
| | - Anne McNamara
- Division of Cellular and Molecular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester M13 9PT, UK
| | - Karen Featherstone
- Division of Endocrinology, Diabetes and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, AV Hill Building, Manchester M13 9PT, UK
| | - David G Spiller
- Division of Cellular and Molecular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester M13 9PT, UK
| | - David A Rand
- Warwick Systems Biology Centre, University of Warwick, Coventry CV4, 7AL, UK
| | | | - Michael R H White
- Division of Cellular and Molecular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester M13 9PT, UK.
| | - Julian R E Davis
- Division of Endocrinology, Diabetes and Gastroenterology, School of Medical Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, AV Hill Building, Manchester M13 9PT, UK.
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6
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Formosa R, Vassallo J. The Complex Biology of the Aryl Hydrocarbon Receptor and Its Role in the Pituitary Gland. Discov Oncol 2017. [PMID: 28634910 DOI: 10.1007/s12672-017-0300-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor best known for its ability to mediate the effects of environmental toxins such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD or dioxin), polycyclic aromatic hydrocarbons (PAHs), benzene, and polychlorinated biphenyls (PCBs) through the initiation of transcription of a number of metabolically active enzymes. Therefore, the AHR has been studied mostly in the context of xenobiotic signaling. However, several studies have shown that the AHR is constitutively active and plays an important role in general cell physiology, independently of its activity as a xenobiotic receptor and in the absence of exogenous ligands. Within the pituitary, activation of the AHR by environmental toxins has been implicated in disruption of gonadal development and fertility. Studies carried out predominantly in mouse models have revealed the detrimental influence of several environmental toxins on specific cell lineages of the pituitary tissue mediated by activation of AHR and its downstream effectors. Activation of AHR during fetal development adversely affected pituitary development while adult models exposed to AHR ligands demonstrated varying degrees of pituitary dysfunction. Such dysfunction may arise as a result of direct effects on pituitary cells or indirect effects on the hypothalamic-pituitary-gonadal axis. This review offers in-depth analysis of all aspects of AHR biology, with a particular focus on its role and activity within the adenohypophysis and specifically in pituitary tumorigenesis. A novel mechanism by which the AHR may play a direct role in pituitary cell proliferation and tumor formation is postulated. This review therefore attempts to cover all aspects of the AHR's role in the pituitary tissue, from fetal development to adult physiology and the pathophysiology underlying endocrine disruption and pituitary tumorigenesis.
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Affiliation(s)
- Robert Formosa
- Department of Medicine, Faculty of Medicine and Surgery, University of Malta, MSD 2080, Msida, Malta
| | - Josanne Vassallo
- Department of Medicine, Faculty of Medicine and Surgery, University of Malta, MSD 2080, Msida, Malta. .,Neuroendocrine Clinic, Department of Medicine, Mater Dei Hospital, Msida, Malta.
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7
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Isbel L, Prokopuk L, Wu H, Daxinger L, Oey H, Spurling A, Lawther AJ, Hale MW, Whitelaw E. Wiz binds active promoters and CTCF-binding sites and is required for normal behaviour in the mouse. eLife 2016; 5. [PMID: 27410475 PMCID: PMC4977153 DOI: 10.7554/elife.15082] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 07/09/2016] [Indexed: 12/26/2022] Open
Abstract
We previously identified Wiz in a mouse screen for epigenetic modifiers. Due to its known association with G9a/GLP, Wiz is generally considered a transcriptional repressor. Here, we provide evidence that it may also function as a transcriptional activator. Wiz levels are high in the brain, but its function and direct targets are unknown. ChIP-seq was performed in adult cerebellum and Wiz peaks were found at promoters and transcription factor CTCF binding sites. RNA-seq in Wiz mutant mice identified genes differentially regulated in adult cerebellum and embryonic brain. In embryonic brain most decreased in expression and included clustered protocadherin genes. These also decreased in adult cerebellum and showed strong Wiz ChIP-seq enrichment. Because a precise pattern of protocadherin gene expression is required for neuronal development, behavioural tests were carried out on mutant mice, revealing an anxiety-like phenotype. This is the first evidence of a role for Wiz in neural function. DOI:http://dx.doi.org/10.7554/eLife.15082.001
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Affiliation(s)
- Luke Isbel
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia
| | - Lexie Prokopuk
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia
| | - Haoyu Wu
- Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Lucia Daxinger
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia.,Department of Human Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Harald Oey
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia
| | - Alex Spurling
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia
| | - Adam J Lawther
- Department of Psychology and Counselling, La Trobe University, Melbourne, Australia.,School of Psychology and Public Health, La Trobe University, Melbourne, Australia
| | - Matthew W Hale
- Department of Psychology and Counselling, La Trobe University, Melbourne, Australia.,School of Psychology and Public Health, La Trobe University, Melbourne, Australia
| | - Emma Whitelaw
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Melbourne, Australia
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8
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Harten SK, Oey H, Bourke LM, Bharti V, Isbel L, Daxinger L, Faou P, Robertson N, Matthews JM, Whitelaw E. The recently identified modifier of murine metastable epialleles, Rearranged L-Myc Fusion, is involved in maintaining epigenetic marks at CpG island shores and enhancers. BMC Biol 2015; 13:21. [PMID: 25857663 PMCID: PMC4381397 DOI: 10.1186/s12915-015-0128-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 02/23/2015] [Indexed: 01/08/2023] Open
Abstract
Background We recently identified a novel protein, Rearranged L-myc fusion (Rlf), that is required for DNA hypomethylation and transcriptional activity at two specific regions of the genome known to be sensitive to epigenetic gene silencing. To identify other loci affected by the absence of Rlf, we have now analysed 12 whole genome bisulphite sequencing datasets across three different embryonic tissues/stages from mice wild-type or null for Rlf. Results Here we show that the absence of Rlf results in an increase in DNA methylation at thousands of elements involved in transcriptional regulation and many of the changes occur at enhancers and CpG island shores. ChIP-seq for H3K4me1, a mark generally found at regulatory elements, revealed associated changes at many of the regions that are differentially methylated in the Rlf mutants. RNA-seq showed that the numerous effects of the absence of Rlf on the epigenome are associated with relatively subtle effects on the mRNA population. In vitro studies suggest that Rlf’s zinc fingers have the capacity to bind DNA and that the protein interacts with other known epigenetic modifiers. Conclusion This study provides the first evidence that the epigenetic modifier Rlf is involved in the maintenance of DNA methylation at enhancers and CGI shores across the genome. Electronic supplementary material The online version of this article (doi:10.1186/s12915-015-0128-2) contains supplementary material, which is available to authorized users.
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9
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Takeda H, Wei Z, Koso H, Rust AG, Yew CCK, Mann MB, Ward JM, Adams DJ, Copeland NG, Jenkins NA. Transposon mutagenesis identifies genes and evolutionary forces driving gastrointestinal tract tumor progression. Nat Genet 2015; 47:142-50. [PMID: 25559195 DOI: 10.1038/ng.3175] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Accepted: 12/04/2014] [Indexed: 12/14/2022]
Abstract
To provide a more comprehensive understanding of the genes and evolutionary forces driving colorectal cancer (CRC) progression, we performed Sleeping Beauty (SB) transposon mutagenesis screens in mice carrying sensitizing mutations in genes that act at different stages of tumor progression. This approach allowed us to identify a set of genes that appear to be highly relevant for CRC and to provide a better understanding of the evolutionary forces and systems properties of CRC. We also identified six genes driving malignant tumor progression and a new human CRC tumor-suppressor gene, ZNF292, that might also function in other types of cancer. Our comprehensive CRC data set provides a resource with which to develop new therapies for treating CRC.
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Affiliation(s)
- Haruna Takeda
- 1] Division of Genomics and Genetics, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore. [2] Department of Oncologic Pathology, School of Medicine, Kanazawa Medical University, Ishikawa, Japan
| | - Zhubo Wei
- Cancer Research Program, Houston Methodist Research Institute, Houston, Texas, USA
| | - Hideto Koso
- 1] Division of Genomics and Genetics, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore. [2] Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Alistair G Rust
- Experimental Cancer Genetics, Wellcome Trust Sanger Institute, Hinxton, UK
| | - Christopher Chin Kuan Yew
- Division of Genomics and Genetics, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore
| | - Michael B Mann
- 1] Division of Genomics and Genetics, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore. [2] Cancer Research Program, Houston Methodist Research Institute, Houston, Texas, USA
| | - Jerrold M Ward
- Division of Genomics and Genetics, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore
| | - David J Adams
- Experimental Cancer Genetics, Wellcome Trust Sanger Institute, Hinxton, UK
| | - Neal G Copeland
- 1] Division of Genomics and Genetics, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore. [2] Cancer Research Program, Houston Methodist Research Institute, Houston, Texas, USA
| | - Nancy A Jenkins
- 1] Division of Genomics and Genetics, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore. [2] Cancer Research Program, Houston Methodist Research Institute, Houston, Texas, USA
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10
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Dioxin-induced retardation of development through a reduction in the expression of pituitary hormones and possible involvement of an aryl hydrocarbon receptor in this defect: a comparative study using two strains of mice with different sensitivities to dioxin. Toxicol Appl Pharmacol 2014; 278:220-9. [PMID: 24793433 DOI: 10.1016/j.taap.2014.04.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/19/2014] [Accepted: 04/21/2014] [Indexed: 11/23/2022]
Abstract
We have previously revealed that treating pregnant rats with 2,3,7,8-tetracholorodibenzo-p-dioxin (TCDD) reduces the expression of gonadotropins and growth hormone (GH) in the fetal and neonatal pituitary. A change in gonadotropin expression impairs the testicular expression of steroidogenic proteins in perinatal pups, and imprint defects in sexual behavior after reaching maturity. In this study, we examined whether TCDD also affects the expression of gonadotropin and GH in mice using C57BL/6J and DBA/2J strains which express the aryl hydrocarbon receptor (Ahr) exhibiting a different affinity for TCDD. When pregnant C57BL/6J mice at gestational day (GD) 12 were given oral TCDD (0.2-20 μg/kg), all doses significantly attenuated the pituitary expression of gonadotropin mRNAs in fetuses at GD18. On the other hand, in DBA/2J mice, a much higher dose of TCDD (20 μg/kg) was needed to produce a significant attenuation. Such reduction in the C57BL/6J strain continued until at least postnatal day (PND) 4. In agreement with this, TCDD reduced the testicular expression of steroidogenic proteins in C57BL/6J neonates at PND2 and 4, although the same did not occur in the fetal testis and ovary. Furthermore, TCDD reduced the perinatal expression of GH, litter size and the body weight of newborn pups only in the C57BL/6J strain. These results suggest that 1) also in mice, maternal exposure to TCDD attenuates gonadotropin-regulated steroidogenesis and GH expression leading to the impairment of pup development and sexual immaturity; and 2) Ahr activation during the late fetal and early postnatal stages is required for these defects.
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11
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de Moraes DC, Vaisman M, Conceição FL, Ortiga-Carvalho TM. Pituitary development: a complex, temporal regulated process dependent on specific transcriptional factors. J Endocrinol 2012; 215:239-45. [PMID: 22872762 DOI: 10.1530/joe-12-0229] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Pituitary organogenesis is a highly complex and tightly regulated process that depends on several transcription factors (TFs), such as PROP1, PIT1 (POU1F1), HESX1, LHX3 and LHX4. Normal pituitary development requires the temporally and spatially organised expression of TFs and interactions between different TFs, DNA and TF co-activators. Mutations in these genes result in different combinations of hypopituitarism that can be associated with structural alterations of the central nervous system, causing the congenital form of panhypopituitarism. This review aims to elucidate the complex process of pituitary organogenesis, to clarify the role of the major TFs, and to compile the lessons learned from functional studies of TF mutations in panhypopituitarism patients and TF deletions or mutations in transgenic animals.
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Affiliation(s)
- Débora Cristina de Moraes
- Laboratório de Endocrinologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Avenida Carlos Chagas Filho, s/n, Rio de Janeiro, Brasil.
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12
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Insulin-like growth factor 1 mediates negative feedback to somatotroph GH expression via POU1F1/CREB binding protein interactions. Mol Cell Biol 2012; 32:4258-69. [PMID: 22890843 DOI: 10.1128/mcb.00171-12] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Circulating insulin-like growth factor 1 (IGF-1) has been shown to act as a negative feedback regulator of growth hormone (GH) gene expression; however, the mechanism of this negative feedback is poorly understood. Activation and regulation of GH gene expression require the binding of the transcription factor POU1F1 to the GH promoter along with cyclic AMP (cAMP) response element binding protein (CREB) binding protein (CBP). We investigate the role of CBP as a target of IGF-1 somatotroph regulation using the MtT/S somatotroph cell line. IGF-1 significantly inhibits basal GH mRNA levels but not POU1F1 levels. Chromatin immunoprecipitation assays demonstrate inhibition of CBP binding to the GH promoter after IGF-1 treatment. We hypothesized that IGF-1 receptor (IGF-1R) signaling disrupts the POU1F1/CBP complex to inhibit gene expression. In support, the use of a mutant CBP (S436A) construct, which lacks a critical phosphorylation site, leads to the loss of IGF-1 inhibition. The studies of CBP (S436A) knock-in mice show elevated serum GH levels, a greater response to GH releasing hormone (GHRH) stimulation along with lower weight gain, and decreased body fat. Our data confirm the inhibitory effects of IGF-1 on GH expression at the level of the promoter and provide evidence of CBP's role as a target of IGF-1R signaling.
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13
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Abstract
Many transcription factors have important roles in the function and differentiation of the human pituitary adenomas. Forkhead box gene transcription factor L2, Foxl2, is expressed during mouse pituitary development and co-localizes with the expression of α-glycoprotein hormone subunit (αGSU). In addition, Foxl2 regulates expression of the αGSU gene (Cga) in cell culture. To elucidate the functional role of FOXL2 in the human pituitary, we examined the expression and localization of FOXL2 in normal human pituitaries and various types of pituitary adenomas. Human pituitary adenomas were obtained by trans-sphenoidal surgery from 67 patients. Three normal adult pituitaries were obtained from autopsies of non-endocrine cases. The localization of FOXL2 and pituitary hormones in these pituitary patients was examined by immunohistochemical staining and RT-PCR. Quantitative analysis of FOXL2 protein was performed by immunoblotting. FOXL2 was localized in the nuclei of ∼20% of normal pituitary cells that also co-expressed gonadotropins including follicule-stimulating hormone β (FSHβ), luteinizing hormone β (LHβ), and αGSU, whereas it was observed in minor proportion of thyroid-stimulating hormone (TSH)-producing cells, prolactin (PRL)-producing cells, and precursor of adrenocorticotropic hormone (ACTH)-producing cells. FOXL2 immunoreactivity was not detected in growth hormone (GH)-producing cells or S100-positive folliculo-stellate cells. In human pituitary adenomas, FOXL2 was expressed in the nuclei of the adenoma cells. FOXL2 was detected in 13 of 15 gonadotropin-subunit-producing adenoma (Gn-oma) cases and 8 of 11 null cell adenoma cases, but its incidence was reduced or not detected in the other types of adenomas. The results of this study suggest that FOXL2 contributes to the human-specific functional expression and the differentiation of gonadotroph cells and adenomas.
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15
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Giordano M, Godi M, Mellone S, Petri A, Vivenza D, Tiradani L, Carlomagno Y, Ferrante D, Arrigo T, Corneli G, Bellone S, Giacopelli F, Santoro C, Bona G, Momigliano-Richiardi P. A functional common polymorphism in the vitamin D-responsive element of the GH1 promoter contributes to isolated growth hormone deficiency. J Clin Endocrinol Metab 2008; 93:1005-12. [PMID: 18160466 DOI: 10.1210/jc.2007-1918] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Causal mutations have been detected only in a minority of isolated GH deficiency (IGHD) patients. Idiopathic IGHD might be the result of the interaction between several low-penetrance genetic factors and the environment. OBJECTIVE The aim of this study was to test the contribution to IGHD of genetic variations in the GH1 gene regulatory regions. DESIGN AND PATIENTS A case-control association study was performed including 118 sporadic IGHD patients with a nonsevere phenotype (height -4/-1 sd score and partial GH deficiency) and two control groups, normal stature (n=200) and short-stature individuals with normal GH secretion (n=113). Seven single-nucleotide polymorphisms in the GH1 promoter, one in the IVS4 region, and two in the locus control region were analyzed. RESULTS The -57T allele within the vitamin D-responsive element showed a positive significant association when comparing patients with normal (P=0.006) or short stature (P=0.0011) controls. The genotype -57TT showed an odds ratio of 2.93 (1.44-5.99) and 2.99 (1.42-6.31), respectively. The functional relevance of the -57 variation was demonstrated by the luciferase assay in the presence of vitamin D. The vitamin D-induced inhibition of luciferase activity was significantly (P=0.012) stronger for the promoter haplotype carrying the associated variation -57T [haplotype #1 (hp#1)] with respect to hp#2, bearing -57G. Replacement of the T with a G at -57 on hp#1 abolished the repression, demonstrating that the T at position -57 is necessary to determine the greater vitamin D-induced inhibitory effect of hp#1. EMSA experiments showed a different band-shift pattern of the T and G sequences. CONCLUSION The common -57G-->T polymorphism contributes to IGHD susceptibility, indicating that it may have a multifactorial etiology.
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Affiliation(s)
- Mara Giordano
- Laboratory of Human Genetics, Department of Medical Sciences, University of Eastern Piedmont, Via Solaroli 17, 28100 Novara, Italy.
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16
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de Guise C, Lacerte A, Rafiei S, Reynaud R, Roy M, Brue T, Lebrun JJ. Activin inhibits the human Pit-1 gene promoter through the p38 kinase pathway in a Smad-independent manner. Endocrinology 2006; 147:4351-62. [PMID: 16740974 DOI: 10.1210/en.2006-0444] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The pituitary transcription factor Pit-1 regulates hormonal production from the anterior pituitary gland. However, the mechanisms by which Pit-1 gene expression is regulated in humans are poorly understood. Activin, a member of the TGFbeta superfamily, acts as a negative regulator of cell growth and prolactin gene expression in lactotrope cells. In this study, we show that activin negatively regulates the human Pit-1 gene promoter. We defined a 117-bp element within the Pit-1 promoter that is sufficient to relay these inhibitory effects. We further investigated the signaling pathways that mediate activin-induced inhibition of Pit-1 gene promoter in pituitary lactotrope cells. We found that the activin effects on Pit-1 gene regulation are Smad independent and require the p38 MAPK pathway. Specifically, blocking p38 kinase activity reverses activin-mediated inhibition of the Pit-1 gene promoter. Together, our results highlight the p38 MAPK pathway as a key regulator of activin function in pituitary lactotrope cells and further emphasizes the critical role played by activin in regulating hormonal production in the pituitary gland.
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Affiliation(s)
- Chantal de Guise
- Hormones and Cancer Research Unit, Department of Medicine, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, Quebec, Canada H3A 1A1
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17
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Trujillo MA, Sakagashira M, Eberhardt NL. The human growth hormone gene contains a silencer embedded within an Alu repeat in the 3'-flanking region. Mol Endocrinol 2006; 20:2559-75. [PMID: 16762973 DOI: 10.1210/me.2006-0147] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Alu family sequences are middle repetitive short interspersed elements (SINEs) dispersed throughout vertebrate genomes that can modulate gene transcription. The human (h) GH locus contains 44 complete and four partial Alu elements. An Sx Alu repeat lies in close proximity to the hGH-1 and hGH-2 genes in the 3'-flanking region. Deletion of the Sx Alu repeat in reporter constructs containing hGH-1 3'-flanking sequences increased reporter activity in transfected pituitary GC cells, suggesting this region contained a repressor element. Analysis of multiple deletion fragments from the 3'-flanking region of the hGH-1 gene revealed a strong orientation- and position-independent silencing activity mapping between nucleotides 2158 and 2572 encompassing the Sx Alu repeat. Refined mapping revealed that the silencer was a complex element comprising four discrete entities, including a core repressor domain (CRD), an antisilencer domain (ASE) that contains elements mediating the orientation-independent silencer activity, and two domains flanking the CRD/ASE that modulate silencer activity in a CRD-dependent manner. The upstream modulator domain is also required for orientation-independent silencer function. EMSA with DNA fragments representing all of the silencer domains yielded a complex pattern of DNA-protein interactions indicating that numerous GC cell nuclear proteins bind specifically to the CRD, ASE, and modulator domains. The silencer is GH promoter dependent and, in turn, its presence decreases the rate of promoter-associated histone acetylation resulting in a significant decrease of RNA polymerase II recruitment to the promoter. The silencer may provide for complex regulatory control of hGH gene expression in pituitary cells.
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Affiliation(s)
- Miguel A Trujillo
- Department of Medicine, Mayo Clinic/Mayo Foundation Rochester, Minnesota 55905, USA
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18
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Giordano M, Godi M, Giacopelli F, Lessi M, Mellone S, Paracchini R, Petri A, Bellone J, Ravazzolo R, Bona G, Momigliano-Richiardi P. A variation in a Pit-1 site in the growth hormone gene (GH1) promoter induces a differential transcriptional activity. Mol Cell Endocrinol 2006; 249:51-7. [PMID: 16517055 DOI: 10.1016/j.mce.2006.01.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Revised: 12/23/2005] [Accepted: 01/19/2006] [Indexed: 11/28/2022]
Abstract
The proximal promoter of the human growth hormone gene (GH1) is highly polymorphic. We tested if promoter haplotypes differing at possibly functional sites, namely -278T/G (in the NF1 binding site), -75A/G (in the proximal Pit-1 binding site) and -57G/T (in the VDR binding site), induced a different luciferase activity when transfected in a rat pituitary cell line. The presence of a G instead of an A at position -75 induced a more than two-fold reduced activity (p<0.0001). In accordance with this findings the electrophoretic mobility shift assay demonstrated a reduced affinity of the -75G for the pituitary transcription factor Pit-1. Despite the strong effect of this polymorphism in vitro, the -75G variation was not associated to an impairment of the GH secretion in vivo.
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Affiliation(s)
- Mara Giordano
- Laboratorio di Genetica Umana, Dipartimento di Scienze Mediche and IRCAD, Università del Piemonte Orientale, Novara, Italy.
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19
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Flynn MP, Hurley DL. Growth hormone transcription factor ZN-16 genomic coding regions are composed of a single exon and are evolutionarily conserved in mammals. Gene 2005; 368:78-83. [PMID: 16303260 DOI: 10.1016/j.gene.2005.10.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2005] [Revised: 10/11/2005] [Accepted: 10/13/2005] [Indexed: 11/16/2022]
Abstract
The structure of the gene encoding ZN-16, a transcription factor that binds to the mammalian growth hormone promoter in tandem with Pit-1, was determined in order to elucidate the exon-intron organization of the 16 zinc finger domains of the protein. Southern hybridization of mouse genomic DNA showed fragments with sizes identical to those predicted from mouse ZN-16 cDNA for two different probes covering the 2200 aa coding frame. Mouse genome database sequences also showed no introns in the zn-16 coding regions on chromosome 4. Analysis of human zn-16 by Southern hybridization and genomic database sequence analysis also indicated a single exon for the human protein coding sequences. BLASTP query of available genomic databases with critical zinc finger residues from mouse ZN-16 identified highly similar canine, bovine, and chimpanzee genomic sequences that encode proteins. Phylogenetic analysis of these mammalian proteins resulted in relationships as would be expected in species spanning rodents to humans. All six independent zn-16 sequences show a single exon coding region with no introns, a similarity ruling out the possibility that these genomic sequences are pseudogenes. Thus, mammalian zn-16 has a compact single exon structure encoding a very large protein (2200-3000 aa), the conservation of which may have functional implications such as the importance of posttranscriptional modifications.
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Affiliation(s)
- Maxfield P Flynn
- Department of Biochemistry, Tulane University School of Medicine, New Orleans, LA, USA
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20
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Cai J, Xue H, Zhan M, Rao MS. Characterization of Progenitor-Cell-Specific Genes Identified by Subtractive Suppression Hybridization. Dev Neurosci 2005; 26:131-47. [PMID: 15711056 DOI: 10.1159/000082133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2003] [Accepted: 02/23/2004] [Indexed: 11/19/2022] Open
Abstract
We have utilized subtractive suppression hybridization (SSH) to identify differentially expressed genes present in either neuroepithelial (NEP) cells or glial restricted precursor (GRP) cells. Eighteen clones enriched in GRP cells and 28 in NEP cells were identified. Five of the GRP-specific clones (tenascin C, cystatin C, GABA transporter 3, extracellular matrix molecule 2 and H2-4) were characterized further, and their glial specificity was confirmed by RT-PCR, in situ hybridization and immunocytochemistry. H2-4 (an expressed sequence tag) was shown to be part of chondroitin sulfate proteoglycan 3. Overall, our results show that SSH can be used to identify lineage- and stage-specific markers and that extracellular matrix molecules likely play important roles in the migration and differentiation of GRPs.
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Affiliation(s)
- Jingli Cai
- Laboratoryof Neurosciences, National Institute on Aging, Baltimore, MD 21224, USA
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21
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Lipkin SM, Rozek LS, Rennert G, Yang W, Chen PC, Hacia J, Hunt N, Shin B, Fodor S, Kokoris M, Greenson JK, Fearon E, Lynch H, Collins F, Gruber SB. The MLH1 D132H variant is associated with susceptibility to sporadic colorectal cancer. Nat Genet 2004; 36:694-9. [PMID: 15184898 DOI: 10.1038/ng1374] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Accepted: 04/22/2004] [Indexed: 01/07/2023]
Abstract
Most susceptibility to colorectal cancer (CRC) is not accounted for by known risk factors. Because MLH1, MSH2 and MSH6 mutations underlie high-penetrance CRC susceptibility in hereditary nonpolyposis colon cancer (HNPCC), we hypothesized that attenuated alleles might also underlie susceptibility to sporadic CRC. We looked for gene variants associated with HNPCC in Israeli probands with familial CRC unstratified with respect to the microsatellite instability (MSI) phenotype. Association studies identified a new MLH1 variant (415G-->C, resulting in the amino acid substitution D132H) in approximately 1.3% of Israeli individuals with CRC self-described as Jewish, Christian and Muslim. MLH1 415C confers clinically significant susceptibility to CRC. In contrast to classic HNPCC, CRCs associated with MLH1 415C usually do not have the MSI defect, which is important for clinical mutation screening. Structural and functional analyses showed that the normal ATPase function of MLH1 is attenuated, but not eliminated, by the MLH1 415G-->C mutation. The new MLH1 variant confers a high risk of CRC and identifies a previously unrecognized mechanism in microsatellite-stable tumors. These studies suggest that variants of mismatch repair proteins with attenuated function may account for a higher proportion of susceptibility to sporadic microsatellite-stable CRC than previously assumed.
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Affiliation(s)
- Steven M Lipkin
- Division of Oncology, Department of Medicine, University of California, Irvine, Irvine, California 92697, USA.
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22
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Cheng RYS, Hockman T, Crawford E, Anderson LM, Shiao YH. Epigenetic and gene expression changes related to transgenerational carcinogenesis. Mol Carcinog 2004; 40:1-11. [PMID: 15108325 DOI: 10.1002/mc.20022] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Transgenerational carcinogenesis refers to transmission of cancer risk to the untreated progeny of parents exposed to carcinogens before mating. Accumulated evidence suggests that the mechanism of this process is epigenetic, and might involve hormonal and gene expression changes in offspring. To begin to test this hypothesis, we utilized a mouse model (NIH Swiss) in which exposure of fathers to Cr(III) chloride 2 wk before mating can alter incidence of neoplastic and nonneoplastic changes in offspring tissues. Utilizing a MS-RDA approach, we found that the sperm of these fathers had a significantly higher percentage of undermethylated copies of the 45S ribosomal RNA gene (rRNA); this finding was confirmed by bisulfite sequencing. Because gene methylation is a known mechanism of expression control in germ cells, and ribosomal RNA levels have been linked to cancer, these findings are consistent with the hypothesis. Secondly, we observed that offspring of Cr(III)-treated fathers were significantly heavier than controls, and had higher levels of serum T3. Possible effects of T3 levels on gene expression in the offspring were examined by microarray analysis of cDNAs from liver. A total of 58 genes, including 25 named genes, had expression ratios that correlated significantly with serum T3 ratios at P </= 0.001. Some of these genes have potential roles in growth and/or tumor suppression. These results also support the hypothesis of an epigenetic and/or gene expression-based mechanism for transgenerational carcinogenesis. Published 2004 Wiley-Liss, Inc.
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Affiliation(s)
- Robert Y-S Cheng
- Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Frederick, Maryland 21702, USA
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23
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Savage JJ, Yaden BC, Kiratipranon P, Rhodes SJ. Transcriptional control during mammalian anterior pituitary development. Gene 2004; 319:1-19. [PMID: 14597167 DOI: 10.1016/s0378-1119(03)00804-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The mammalian anterior pituitary gland is a compound endocrine organ that regulates reproductive development and fitness, growth, metabolic homeostasis, the response to stress, and lactation, by actions on target organs such as the gonads, the liver, the thyroid, the adrenals, and the mammary gland. The protein and peptide hormones that control these physiological parameters are secreted by specialized pituitary cell types that derive from a common origin in the early ectoderm. Collectively, the broad physiological importance of the pituitary gland, its intriguing organogenesis, and the clinical and agricultural significance of its actions, have established pituitary development as an excellent model system for the study of the gene-regulatory cascades that guide vertebrate cell determination and differentiation. We review the transcriptional pathways that regulate the commitment of the individual pituitary cell lineages and that subsequently modulate trophic hormone gene activity in the differentiated cells of the mature gland.
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Affiliation(s)
- Jesse J Savage
- Department of Biology, Indiana University Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, Indianapolis, IN 46202-5132, USA
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24
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Malvagia S, Poggi GM, Pasquini E, Donati MA, Pela I, Morrone A, Zammarchi E. The de novo Q167K mutation in the POU1F1 gene leads to combined pituitary hormone deficiency in an Italian patient. Pediatr Res 2003; 54:635-40. [PMID: 12904605 DOI: 10.1203/01.pdr.0000084113.41375.1e] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The POU1F1 gene encodes a transcription factor that is important for the development and differentiation of the cells producing GH, prolactin, and TSH in the anterior pituitary gland. Patients with POU1F1 mutations show a combined pituitary hormone deficiency with low or absent levels of GH, prolactin, and TSH. Fourteen mutations have been reported in the POU1F1 gene up to now. These genetic lesions can be inherited either in an autosomal dominant or an autosomal recessive mode. We report on the first Italian patient, a girl, affected by combined pituitary hormone deficiency. The patient was found to be positive for congenital hypothyroidism (with low TSH levels) at neonatal screening. Substitutive therapy was started, but subsequent growth was very poor, although psychomotor development was substantially normal. Hospitalized at 10 mo she showed hypotonic crises, growth retardation, delayed bone age, and facial dysmorphism. In addition to congenital hypothyroidism, GH and prolactin deficiencies were found. Mutation DNA analysis of the patient's POU1F1 gene identified the novel Q167K amino acid change at the heterozygous level. The highly conserved Q167 residue is located in the POU-specific domain. No mutation was detected in the other allele. DNA analysis in the proband's parents did not identify this amino acid substitution, suggesting a de novo genetic lesion. From these data it can be hypothesized that the Q167K mutation has a dominant negative effect.
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Affiliation(s)
- Sabrina Malvagia
- Department of Paediatrics, University of Florence, 50132 Florence, Italy.
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25
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Targeted ablation of gonadotrophs in transgenic mice depresses prolactin but not growth hormone gene expression at birth as measured by quantitative mRNA detection. J Biomed Sci 2003. [DOI: 10.1007/bf02256333] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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26
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Hashimoto Y, Cisternino M, Cohen LE. A novel nonsense mutation in the Pit-1 gene: evidence for a gene dosage effect. J Clin Endocrinol Metab 2003; 88:1241-7. [PMID: 12629113 DOI: 10.1210/jc.2002-021510] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The POU transcription factor Pit-1 functions in the development of somatotrophs, lactotrophs, and thyrotrophs of the anterior pituitary gland. It also plays a role in cell-specific gene expression and regulation of the gene products from these cell types, GH, prolactin, and TSH, respectively. In the present report we studied a patient with severe growth failure. Provocative studies revealed undetectable GH, prolactin, and TSH levels, and her pituitary gland was hypoplastic on magnetic resonance imaging. She had a novel homozygous nonsense mutation in the 3' end of the first alpha-helix of the POU-specific domain of the Pit-1 gene. This mutation results in a truncated protein with loss of most of the Pit-1 DNA-binding domains. Interestingly, her parents, who each have one mutant allele, have evidence of mild endocrine dysfunction. Thus, two normal copies of the Pit-1 gene appear necessary for full Pit-1 gene function.
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Affiliation(s)
- Yukiko Hashimoto
- Division of Endocrinology, Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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27
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Affiliation(s)
- Laurie E Cohen
- Division of Endocrinology, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
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28
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Gordon DF, Woodmansee WW, Black JN, Dowding JM, Bendrick-Peart J, Wood WM, Ridgway EC. Domains of Pit-1 required for transcriptional synergy with GATA-2 on the TSH beta gene. Mol Cell Endocrinol 2002; 196:53-66. [PMID: 12385825 DOI: 10.1016/s0303-7207(02)00223-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Previous studies showed that Pit-1 functionally cooperates with GATA-2 to stimulate transcription of the TSH beta gene. Pit-1 and GATA-2 are uniquely coexpressed in pituitary thyrotropes and activate transcription by binding to a composite promoter element. To define the domains of Pit-1 important for functional cooperativity with GATA-2, we cotransfected a set of Pit-1 deletions with an mTSH beta-luciferase reporter. Plasmids were titrated to express equivalent amounts of protein. A mutant containing a deletion of the hinge region between the POU and homeodomains retained the ability to fully synergize with GATA-2. In contrast, mutants containing deletions of amino acids 2-80 or 72-125 demonstrated 56 or 34% of the synergy found with the full-length protein, suggesting that these regions contributed to cooperativity. Mutants with deletions of the POU-specific or homeodomain further reduced the effect signifying the requirement for DNA binding. GST interaction studies demonstrated that only the homeodomain of Pit-1 interacted with GATA-2. Finally, several mutations between the Pit-1 and GATA-2 sites on the TSH beta promoter reduced binding for each factor and greatly reduced ternary complex formation. Thus multiple domains of Pit-1 are required for full synergy with GATA-2 and sequences between the two binding sites contribute to co-occupancy with both factors on the proximal TSH beta promoter.
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Affiliation(s)
- David F Gordon
- Department of Medicine, University of Colorado Health Sciences Center, Box B151, 4200 E Ninth Avenue, Denver, CO 80262, USA.
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29
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McDermott NB, Gordon DF, Kramer CA, Liu Q, Linney E, Wood WM, Haugen BR. Isolation and functional analysis of the mouse RXRgamma1 gene promoter in anterior pituitary cells. J Biol Chem 2002; 277:36839-44. [PMID: 12114515 DOI: 10.1074/jbc.m203689200] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The retinoid X receptor (RXR) isoform RXRgamma has limited tissue expression, including brain, skeletal muscle, and anterior pituitary gland. Within the anterior pituitary gland, RXRgamma expression is limited primarily to the thyrotropes. In this report, we have isolated approximately 3 kb of 5'-flanking DNA of the mouse RXRgamma1 gene. We have identified the major transcription start site in the thyrotrope-derived TtT-97 cells. Transient transfection studies show that a 1.4-kb promoter fragment has full promoter activity in TtT-97 cells. This promoter has much less activity in thyrotrope-derived alphaTSH cells, pituitary-derived GH3 somatomammotropes, and non-pituitary CV-1 cells. None of these cell lines has detectable RXRgamma1 mRNA. A previous report has identified a non-consensus direct repeat (DR-1) element in the RXRgamma2 gene promoter region that mediates stimulation of promoter activity by 9-cis-retinoic acid (9-cis-RA). Inspection of the RXRgamma1 promoter region revealed a non-consensus DR-1 element at -232 bp from the transcription start site. Interestingly, RXRgamma1 promoter activity was suppressed 50% by 9-cis-RA in the TtT-97 thyrotropes. Further experiments in non-pituitary cells showed that suppression of RXRgamma1 promoter activity was RXR-dependent. Mutagenesis of the DR-1 element abrogated suppression of promoter activity by 9-cis-RA, suggesting that this negative regulation requires both RXR and this specific DR-1 element. In summary, we have isolated the mouse RXRgamma1 gene promoter region and identified the major start site in thyrotropes. Promoter activity is uniquely suppressed by 9-cis-RA through a DR-1 element. Isolation and characterization of the mouse RXRgamma1 promoter region provides a tool for further investigation focusing on thyrotrope-specific gene expression as well as negative regulation of genes by retinoic acid.
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Affiliation(s)
- Nicole B McDermott
- Department of Medicine, University of Colorado Health Sciences Center, University of Colorado Cancer Center, Denver, Colorado 80262, USA
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30
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Shewchuk BM, Liebhaber SA, Cooke NE. Specification of unique Pit-1 activity in the hGH locus control region. Proc Natl Acad Sci U S A 2002; 99:11784-9. [PMID: 12189206 PMCID: PMC129346 DOI: 10.1073/pnas.182418199] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The human GH (hGH) gene cluster is regulated by a remote 5' locus control region (LCR). HSI, an LCR component located 14.5 kb 5' to the hGH-N promoter, constitutes the primary determinant of high-level hGH-N activation in pituitary somatotropes. HSI encompasses an array of three binding sites for the pituitary-specific POU homeodomain factor Pit-1. In the present report we demonstrate that all three Pit-1 sites in the HSI array contribute to LCR activity in vivo. Furthermore, these three sites as a unit are fully sufficient for position-independent and somatotrope-restricted hGH-N transgene activation. In contrast, the hGH-N transgene is not activated by Pit-1 sites native to either the hGH-N or rat (r)GH gene promoters. These findings suggest that the structures of the Pit-1 binding sites at HSI specify distinct chromatin-dependent activities essential for LCR-mediated activation of hGH in the developing pituitary.
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Affiliation(s)
- Brian M Shewchuk
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
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31
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Abstract
Pituitary gland commitment from oral ectoderm occurs in response to inductive signals from the neuroepithelium of the ventral diencephalon. Invagination of the oral ectoderm leads to the creation of Rathke's pouch. Intensified cell proliferation within Rathke's pouch results in formation of the anterior pituitary lobe. Subsequently, highly differentiated cell types arise sequentially due to overlapping, but distinct, spatial and temporal patterns of signaling molecules and transcription factors. Mutations in some of the pituitary-specific transcription factors have been identified in patients with hypopituitarism, confirming the role of these factors in pituitary development.
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Affiliation(s)
- Laurie E Cohen
- Division of Endocrinology, Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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32
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Argenton F, Vianello S, Bernardini S, Lopreiato R, Colombo L, Bortolussi M. Trout GH promoter analysis reveals a modular pattern of regulation consistent with the diversification of GH gene control and function in vertebrates. Mol Cell Endocrinol 2002; 189:11-23. [PMID: 12039061 DOI: 10.1016/s0303-7207(01)00757-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In vertebrates, growth hormone (GH) gene expression requires the pituitary-specific transcription factor Pit-1/GHF1 but is differently regulated by a variety of factors in different vertebrate species. Here, we have studied the transcriptional activity of the trout GH (tGH) promoter, which is synergistically stimulated by cAMP and glucocorticoid. Gel shift assays indicated that Pit-1 binds as a dimer to three high affinity sites in the -226/+24 tGH region, and that recombinant cAMP response element (CRE)-binding protein (CREB) binds to a CRE situated between the two distal Pit-1 sites. Deletional and mutational transfection experiments, performed in pituitary Pit-1-expressing GC cells, showed that the different Pit-1 sites play distinct roles and are obligatory elements in the mechanisms mediating cAMP and glucocorticoid responses. Remarkably, the results suggest a hierarchical modular model of regulation of the tGH promoter, according to which a critical module, triggered by Pit-1 bound to the proximal Pit-1 site, is necessary and sufficient to turn on and drive basal levels of transcription. The latter may be stimulated synergistically by two Pit-1-dependent reciprocally non-cooperative auxiliary modules, activated by cAMP and glucocorticoid, respectively. Such modularity explains, in evolutionary terms, the crucial role played by Pit-1 in transcriptional activation and the emergence of the wide variety of mechanisms regulating transcriptional levels of GH, prolactin and other Pit-1-target genes in vertebrates.
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Affiliation(s)
- Francesco Argenton
- Dipartimento di Biologia, Università degli Studi di Padova, Università di Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy
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33
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Abstract
Transcription factor GATA-2 contains two copies of a highly conserved zinc finger domain and plays unique roles at an early stage of hematopoietic differentiation. In the mouse pituitary gland, Pit-1-GATA-2 protein-protein interaction has been shown to lead to gene-specific actions to obtain cell-specific roles. In this study, we investigated the expression of GATA-2 and Pit-1 in human pituitary adenomas using reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical techniques. By immunohistochemical analysis, GATA-2 was detected in all of the gonadotropin-subunit (Gn-su)-positive adenomas (n = 8) and in four of five thyroid-stimulating hormone (TSH)-secreting adenomas, but its incidence was low in the other types of adenomas. Pit-1 protein was detected in 4 of 5 TSH-secreting adenomas and in 10 of 10 growth hormone (GH)-secreting adenomas. By RT-PCR analysis, GATA-2 was detected in all Gn-su-positive adenomas and TSH-secreting adenomas, and Pit-1 was detected in all TSH-secreting adenomas and GH-secreting adenomas. These results suggested that GATA-2 contributes to the functional expression and the differentiation of Gn-su-positive adenomas and the TSH-secreting adenomas and that the interaction between GATA-2 and Pit-1 can lead to gene-specific action and differentiation of TSH-secreting adenomas. It is further speculated that GATA-2 and transcriptional interaction with Pit-1 play roles in the functional differentiation of specific pituitary adenomas.
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Affiliation(s)
- Katsuya Umeoka
- Department of Neurosurgery, Nippon Medical School, Tokyo, Japan
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34
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Batt J, Asa S, Fladd C, Rotin D. Pituitary, pancreatic and gut neuroendocrine defects in protein tyrosine phosphatase-sigma-deficient mice. Mol Endocrinol 2002; 16:155-69. [PMID: 11773446 DOI: 10.1210/mend.16.1.0756] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The expression of receptor protein tyrosine phosphatase sigma (PTPfinal sigma) is developmentally regulated in neuronal and neuroendocrine tissues. We have previously shown that mice deficient in PTPfinal sigma demonstrate nervous system abnormalities, pituitary hypoplasia, increased neonatal mortality (60%), and death from a wasting syndrome at 2-3 wk of age (38%). We have now examined the role of PTPfinal sigma on pituitary, pancreas and enteroendocrine cytodifferentiation, hormone production, and development. The adenohypophyses of PTPfinal sigma(-/-) mice were small and exhibited reduced GH and PRL immunoreactivity. Cells containing TSH, LH, FSH, ACTH, pituitary-specific POU homeodomain factor (Pit-1), ER, and steroidogenic factor 1 were found in normal proportions and distributions. The diminished expression of GH and PRL was not associated with apoptosis of somatotrophs or lactotrophs. Pit-1-positive TSH-negative cells were detected, suggesting that impaired GH and PRL synthesis was not attributable to Pit-1 deficiency. In the knockout mice, pancreatic islets were hypoplastic with reduced insulin immunoreactivity, and there was also variable expression of gut hormones. Functionally, the GH deficiency was associated with hypoglycemia and death in the PTPfinal sigma(-/-) neonate and accordingly, ip administration of GH rescued the PTPfinal sigma(-/-) neonate and normalized the blood glucose. These data indicate that PTPfinal sigma plays a major role in differentiation and development of the neuroendocrine system.
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Affiliation(s)
- Jane Batt
- The Hospital for Sick Children, Program in Cell Biology, and Institute of Medical Science and Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1X8, Canada
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35
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Abstract
During the development of the pituitary gland, distinct hormone-producing cell types arise from a common population of ectodermal progenitors, providing an instructive model system for elucidating the molecular mechanisms of patterning and cell type specification in mammalian organogenesis. Recent studies have established that the development of the pituitary occurs through multiple sequential steps, allowing the coordinate control of the commitment, early patterning, proliferation, and positional determination of pituitary cell lineages in response to extrinsic and intrinsic signals. The early phases of pituitary development appear to be mediated through the activities of multiple signaling gradients emanating from key organizing centers that give rise to temporally and spatially distinct patterns of transcription factor expression. The induction of these transcriptional mediators in turn acts to positionally organize specific pituitary cell lineages within an apparently uniform field of ectodermal progenitors. Ultimately, pituitary cell types have proven to be both specified and maintained through the combinatorial interactions of a series of cell-type-restricted transcription factors that dictate the cell autonomous programs of differentiation in response to the transient signaling events.
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Affiliation(s)
- J S Dasen
- Howard Hughes Medical Institute, Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093-0648, USA.
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36
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Andersen B, Rosenfeld MG. POU domain factors in the neuroendocrine system: lessons from developmental biology provide insights into human disease. Endocr Rev 2001; 22:2-35. [PMID: 11159814 DOI: 10.1210/edrv.22.1.0421] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
POU domain factors are transcriptional regulators characterized by a highly conserved DNA-binding domain referred to as the POU domain. The structure of the POU domain has been solved, facilitating the understanding of how these proteins bind to DNA and regulate transcription via complex protein-protein interactions. Several members of the POU domain family have been implicated in the control of development and function of the neuroendocrine system. Such roles have been most clearly established for Pit-1, which is required for formation of somatotropes, lactotropes, and thyrotropes in the anterior pituitary gland, and for Brn-2, which is critical for formation of magnocellular and parvocellular neurons in the paraventricular and supraoptic nuclei of the hypothalamus. While genetic evidence is lacking, molecular biology experiments have implicated several other POU factors in the regulation of gene expression in the hypothalamus and pituitary gland. Pit-1 mutations in humans cause combined pituitary hormone deficiency similar to that found in mice deleted for the Pit-1 gene, providing a striking example of how basic developmental biology studies have provided important insights into human disease.
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Affiliation(s)
- B Andersen
- Department of Medicine, University of California, San Diego, La Jolla, 92093-0648, USA.
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37
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Scully KM, Jacobson EM, Jepsen K, Lunyak V, Viadiu H, Carrière C, Rose DW, Hooshmand F, Aggarwal AK, Rosenfeld MG. Allosteric effects of Pit-1 DNA sites on long-term repression in cell type specification. Science 2000; 290:1127-31. [PMID: 11073444 DOI: 10.1126/science.290.5494.1127] [Citation(s) in RCA: 195] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Reciprocal gene activation and restriction during cell type differentiation from a common lineage is a hallmark of mammalian organogenesis. A key question, then, is whether a critical transcriptional activator of cell type-specific gene targets can also restrict expression of the same genes in other cell types. Here, we show that whereas the pituitary-specific POU domain factor Pit-1 activates growth hormone gene expression in one cell type, the somatotrope, it restricts its expression from a second cell type, the lactotrope. This distinction depends on a two-base pair spacing in accommodation of the bipartite POU domains on a conserved growth hormone promoter site. The allosteric effect on Pit-1, in combination with other DNA binding factors, results in the recruitment of a corepressor complex, including nuclear receptor corepressor N-CoR, which, unexpectedly, is required for active long-term repression of the growth hormone gene in lactotropes.
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Affiliation(s)
- K M Scully
- Howard Hughes Medical Institute, Department of Endocrinology and Metabolism, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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38
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Abstract
Extrinsic and intrinsic signaling gradients determine expression patterns of pituitary-specific factors in the developing anterior pituitary gland. The temporal and spatial relations of these developmental factors are required for the determination of each of the pituitary cell lineages. Rpx is required for early differentiation of the anterior pituitary. The determination of the somatotroph cell line is dependent on the transcription factors Lhx3, Prop-1, and Pit-1. Pit-1 also plays a role in the activation and regulation of the somatotroph gene product, GH. Additional factors such as CREB and the GHRH receptor, may be involved in somatotroph determination, while Zn-15 and Pitx2 may be involved in GH gene activation.
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Affiliation(s)
- L E Cohen
- Division of Endocrinology, Children's Hospital, Boston, MA 02115, USA.
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39
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Su Y, Liebhaber SA, Cooke NE. The human growth hormone gene cluster locus control region supports position-independent pituitary- and placenta-specific expression in the transgenic mouse. J Biol Chem 2000; 275:7902-9. [PMID: 10713106 DOI: 10.1074/jbc.275.11.7902] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human growth hormone (hGH) cluster contains five genes. The hGH-N gene is predominantly expressed in pituitary somatotropes, whereas the remaining four genes, the chorionic somatomammotropin genes (hCS-L, hCS-A, and hCS-B) and hGH-V, are expressed selectively in the placenta. In contrast, the mouse genome contains a single pituitary-specific GH gene and lacks any GH-related CS genes. Activation of the hGH transgene in the mouse is dependent on its linkage to a previously described locus control region (LCR) located -15 to -32 kilobases upstream of the hGH cluster. The sporadic, nonreproducible expression of hCS transgenes lacking the LCR suggests that they may be dependent on hGH LCR activity as well. To determine whether the hCS genes could be expressed with appropriate placental specificity, a series of five transgenic mouse lines carrying an 87-kilobase human genomic insert encompassing the majority of the hGH gene cluster and the entire contiguous LCR was established. All of the hGH cluster genes were appropriately expressed in each of these lines. High level expression of hGH was restricted to the pituitary and hCS to the labyrinthine layer of the placenta. The expression of the GH cluster genes in their respective tissues paralleled transgene copy numbers irrespective of the transgene insertion site in the host mouse genome. These studies have extended the utility of the transgenic mouse model for the analysis of the full spectrum of hGH gene cluster activation. Further, they support a role for the hGH LCR in placental hCS, as well as pituitary hGH gene activation, and expression.
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Affiliation(s)
- Y Su
- Departments of Medicine and Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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40
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López-Bermejo A, Buckway CK, Rosenfeld RG. Genetic defects of the growth hormone-insulin-like growth factor axis. Trends Endocrinol Metab 2000; 11:39-49. [PMID: 10675889 DOI: 10.1016/s1043-2760(99)00226-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Our understanding of the physiology of the growth hormone-insulin-like growth factor (GH-IGF) axis has been characterized by remarkable advances in the past decade, with clarification of genetic defects in the development of somatotropes, GH secretion and action, and IGF synthesis and action. Combined efforts of research in this area and the development of animal models of growth retardation have also indicated new genetic abnormalities that might prove to cause short stature in humans. Genetic defects, both established and hypothetical, are reviewed, and a pragmatic clinical approach to the genetic investigation of short-statured patients is presented.
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Affiliation(s)
- A López-Bermejo
- Department of Pediatrics, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, OR 97201-3098, USA
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41
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Bradford AP, Brodsky KS, Diamond SE, Kuhn LC, Liu Y, Gutierrez-Hartmann A. The Pit-1 homeodomain and beta-domain interact with Ets-1 and modulate synergistic activation of the rat prolactin promoter. J Biol Chem 2000; 275:3100-6. [PMID: 10652292 DOI: 10.1074/jbc.275.5.3100] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pit-1/GHF-1 is a pituitary-specific, POU homeodomain transcription factor required for development of somatotroph, lactotroph, and thyrotroph cell lineages and regulation of the temporal and spatial expression of the growth hormone, prolactin (PRL), and thyrotropin-beta genes. Synergistic interaction of Pit-1 with a member of the Ets family of transcription factors, Ets-1, has been shown to be an important mechanism regulating basal and Ras-induced lactotroph-specific rat (r) PRL promoter activity. Pit-1beta/GHF-2, an alternatively spliced isoform containing a 26-amino acid insert (beta-domain) within its transcription-activation domain, physically interacts with Ets-1 but fails to synergize. By using a series of Pit-1 internal-deletion constructs in a transient transfection protocol to reconstitute rPRL promoter activity in HeLa cells, we have determined that the functional and physical interaction of Pit-1 and Ets-1 is mediated via the POU homeodomain, which is common to both Pit-1 and Pit-1beta. Although the Pit-1 homeodomain is both necessary and sufficient for direct binding to Ets-1 in a DNA-independent manner, an additional interaction surface was mapped to the beta-domain, specific to the Pit-1beta isoform. Thus, the unique transcriptional properties of Pit-1 and Pit-1beta on the rPRL promoter may be due to the formation of functionally distinct complexes of these two Pit-1 isoforms with Ets-1.
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Affiliation(s)
- A P Bradford
- Department of Obstetrics, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
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42
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VanderHeyden TC, Wojtkiewicz PW, Voss TC, Mangin TM, Harrelson Z, Ahlers KM, Phelps CJ, Hurley DL. Mouse growth hormone transcription factor Zn-16: unique bipartite structure containing tandemly repeated zinc finger domains not reported in rat Zn-15. Mol Cell Endocrinol 2000; 159:89-98. [PMID: 10687855 DOI: 10.1016/s0303-7207(99)00200-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rat Zn-15 is a transcription factor activating GH gene expression by synergistic interactions with Pit-1, named for 15 DNA-binding zinc fingers, including fingers IX, X, and XI that are responsible for GH promoter binding. In this study, a mouse cDNA for Zn-15 was characterized. The predicted 2192-amino acid mouse protein is 89% identical to rat (r) Zn-15 overall, and is 97% similar in the C-terminal domain necessary for binding the GH promoter. However, the mouse cDNA encodes 16 zinc fingers, and sequences of rZn-15 pituitary cDNAs were the same as the mouse (m) Zn-16; the rat sequence in GenBank has a one nucleotide offset of a 17-bp segment in the finger V region. The mouse and corrected rat sequences contain four tandemly repeated fingers in the N-terminus, each separated by seven amino acids, typical of zinc finger proteins of the transcription factor IIIA-type. Analysis of mZn-16 expression by RT-PCR showed that the mRNA is, produced at similar levels in normal and GH-deficient Ames dwarf (Prop-1 <df-/->) mouse pituitaries at postnatal day 1. Mouse Zn-16 mRNA also was detected by ribonuclease protection assay in the pre-somatotrophic mouse cell line GHFT1-5. The Zn-16 protein is bipartite in that the N-terminal half displays tandem spacing typical of most zinc finger proteins, while the C-terminal portion contains long linkers between fingers that cooperatively bind to a DNA response element. Expression in early postnatal pituitary and in pre-somatotrophic cells suggests that Zn-16 could play a role in pituitary development prior to somatotroph differentiation.
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Affiliation(s)
- T C VanderHeyden
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118-5698, USA
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43
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Shewchuk BM, Asa SL, Cooke NE, Liebhaber SA. Pit-1 binding sites at the somatotrope-specific DNase I hypersensitive sites I, II of the human growth hormone locus control region are essential for in vivo hGH-N gene activation. J Biol Chem 1999; 274:35725-33. [PMID: 10585453 DOI: 10.1074/jbc.274.50.35725] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The human growth hormone gene cluster is composed of five closely related genes. The 5'-most gene in the cluster, hGH-N, is expressed exclusively in somatotropes and lactosomatotropes of the anterior pituitary. Although the hGH-N promoter contains functional binding sites for multiple transcription factors, including Sp1, Zn-15, and Pit-1, predictable and developmentally appropriate expression of hGH-N transgenes in the mouse pituitary requires the presence of a previously characterized locus control region (LCR) composed of multiple chromatin DNase I hypersensitive sites (HS). LCR determinant(s) necessary for hGH-N transgene activation are largely conferred by two closely spaced HS (HS I,II) located 14.5 kilobase pairs upstream of the hGH-N gene. The region sufficient to mediate this activity has recently been sublocalized to a 404-base pair segment of HS I,II (F14 segment). In the present study, we identified multiple binding sites for the pituitary POU domain transcription factor Pit-1 within this segment. Using a transgenic founder assay, these sites were shown to be required for high level, position-independent, and somatotrope-specific expression of a linked hGH-N transgene. Because the Pit-1 sites in the hGH-N gene promoter are insufficient for such gene activation in vivo, these data suggested a unique chromatin-mediated developmental role for Pit-1 in the hGH LCR.
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Affiliation(s)
- B M Shewchuk
- Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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44
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Abstract
The anterior lobe of the pituitary gland is derived from the oral ectoderm early in gestation. A variety of techniques have been used to understand how early precursor cells differentiate to form the five major cell types that populate the adult anterior lobe. Current evidence suggests that corticotropes arise from a lineage distinct from that of the other four cell types. The cells of the other lineage branch - thyrotropes, gonadotropes, somatotropes and lactotropes - appear to be related because of their dependence on common transcription factors and the frequent occurrence of cells that produce multiple hormones. While thyrotropes arise through two routes, the lineage related to somatotropes and lactotropes appears to be the most important for hormone production. Each cell type can populate the organ and function in the absence of the other cell types, except for lactotropes, which have a strong dependence on somatotropes. Our current knowledge of anterior pituitary cell lineage relationships may contribute to a better understanding of the origin of pituitary adenomas and tumors.
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45
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Cohen LE, Hashimoto Y, Zanger K, Wondisford F, Radovick S. CREB-independent regulation by CBP is a novel mechanism of human growth hormone gene expression. J Clin Invest 1999; 104:1123-30. [PMID: 10525051 PMCID: PMC408577 DOI: 10.1172/jci7308] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Hypothalamic growth hormone-releasing hormone (GHRH) stimulates growth hormone (GH) gene expression in anterior pituitary somatotrophs by binding to the GHRH receptor, a G-protein-coupled transmembrane receptor, and by mediating a cAMP-mediated protein kinase A (PKA) signal-transduction pathway. Two nonclassical cAMP-response element motifs (CGTCA) are located at nucleotides -187/-183 (distal cAMP-response element; dCRE) and -99/-95 (proximal cAMP-response element; pCRE) of the human GH promoter and are required for cAMP responsiveness, along with the pituitary-specific transcription factor Pit-1 (official nomenclature, POU1F1). Although a role for cAMP-response element binding protein (CREB) in GH stimulation by PKA has been suggested, it is unclear how the effect may be mediated. CREB binding protein (CBP) is a nuclear cofactor named for its ability to bind CREB. However, CBP also binds other nuclear proteins. We determined that CBP interacts with Pit-1 and is a cofactor for Pit-1-dependent activation of the human GH promoter. This pathway appears to be independent of CREB, with CPB being the likely target of phosphorylation by PKA.
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Affiliation(s)
- L E Cohen
- Division of Endocrinology, Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
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46
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Dasen JS, Rosenfeld MG. Combinatorial codes in signaling and synergy: lessons from pituitary development. Curr Opin Genet Dev 1999; 9:566-74. [PMID: 10508698 DOI: 10.1016/s0959-437x(99)00015-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The development of the hormone-secreting cell types in the pituitary gland provides an excellent model system in which to explore the complex transcriptional mechanisms underlying the specification and maintenance of differentiated cell types in mammalian organogenesis. Pituitary development is orchestrated through the combinatorial actions of a repertoire of signaling-gradient-induced transcription factors which, on the basis of their distinct and overlapping expression patterns, and functional interactions, ultimately has led to the generation of functionally distinct cell phenotypes from a common ectodermal primordium.
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Affiliation(s)
- J S Dasen
- Howard Hughes Medical Institute Cellular and Molecular Medicine University of California San Diego, Department and School of Medicine La Jolla, California, 92093-0648, USA.
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47
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Abstract
Several homeodomain factors are found in the developing anterior pituitary lobe. The production of these developmental transcription factors has distinct temporal and spatial patterns. By interacting with each other, as well as with other extrinsic and intrinsic signals, they control cell determination and specification. Here, we discuss transcription factors that have been shown to have an in vivo role in pituitary cell-type specification.
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Affiliation(s)
- LE Cohen
- Children's Hospital, Department of Medicine, Division of Endocrinology, 300 Longwood Avenue, Boston, MA 02115, USA
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48
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Dai KS, Liew CC. Chromosomal, in silico and in vitro expression analysis of cardiovascular-based genes encoding zinc finger proteins. J Mol Cell Cardiol 1999; 31:1749-69. [PMID: 10471358 DOI: 10.1006/jmcc.1999.1011] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Three hundred and sixty expressed sequence tags (ESTs) from human heart cDNA libraries corresponding to one hundred and twenty six unique zinc finger proteins (ZFPs) were annotated and classified into seven types of ZFPs as reported previously. Among these 126 cvbZFPs (cardiovascular-based ZFPs), the C(2)H(2)-type and the C(2)C(2)-type are the two major ZFP types which account for more than 80% of ZFP genes present in the cardiovascular system. The expression patterns of 11 randomly selected ZFP genes (at least one for each type) in normal fetal, adult and hypertrophic adult hearts, respectively, were determined using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. The results suggest that ZFPs may be involved in the processes of either developmental control (downregulated or upregulated expression) or basic cellular functional regulation (constant expression). Interestingly, PAF-1 (peroxisome assembly factor-1), a C(3)HC(4)-type ZFP (RING domain-containing ZFP) showing a downregulated expression pattern in normal tissues was found to be upregulated in hypertrophic adult heart, suggesting a possible role for this fetal gene in the pathogenesis of cardiac hypertrophy. In silico Northern analysis of 15 tissues showed that over 90% of cvbZFPs demonstrate widespread tissue distribution, suggesting the vast majority of ZFPs are functionally shared among tissues. The potential importance of transcriptional repressors in cardiovascular development and disease, such as HFHZ, was supported by the observation that one-third (39 of 126) of cvbZFPs possess this function. Of these, 26 are C(2)H(2)-type and the remaining 13 included 8 C(2)C(2)-type, 1 C(3)HC(4)-type, 1 C(2)HC(4)C(HD)-type, 2 C(3)H-type and 1 combination type. Of particular interest was the observation that ZFPs which contain a KRAB domain are the major subtype present (51. 3% of the total repressors in cvbZFPs). Chromosomal distribution analysis showed that mapping loci of cvbZFP genes are concentrated on chromosomes 1, 3, 6, 8, 10, 11, 12, 19 and X. In particular, chromosome 19 appears to be enriched in ZFP genes with C(2)H(2)-type as the predominant type present. Overall, this report provides a fundamental initial step toward understanding the potential role of ZFPs in regulating cadiac development and disease.
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Affiliation(s)
- K S Dai
- The Cardiac Gene Unit, Institute of Medical Science Department of Laboratory Medicine and Pathobiology, University of Toronto, Ontario, Canada
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49
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Abstract
The pituitary is a complex gland and is composed of several cell types, each responsible for the production of specific hormones. In the past, it was thought that one cell could make only one hormone; the concept of plurihormonality was poorly understood. Plurihormonal adenomas were thought to be either composed of multiple cell types, each producing one hormone (plurimorphous adenomas) or composed of poorly differentiated cells that exhibited abnormal production of multiple hormones. However, the molecular factors that determine hormone production have now been identified as transcription factors that target specific hormone genes. These factors have clarified three main pathways of cell differentiation. ACTH-producing corticotrophs are determined by corticotropin upstream transcription-binding element (CUTE) proteins including neuroD1/beta 2. Bihormonal gonadotrophs require expression of steroidgenic factor (SF)-1. The complex family of Pit-1 expressing cells can mature into somatotrophs, mammosomatotrophs, lactotrophs or thyrotrophs with the additional expression of estrogen receptor (ER) alpha, which enhances PRL secretion, or thyrotroph embryonic factor (TEF) which stimulates TSH-beta production. The recognition of these molecular determinants of adenohypophysial cytodifferentiation has clarified the patterns of plurihormonality which have been recognized in pituitary adenomas and provide a framework for classification of these tumors.
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Affiliation(s)
- S L Asa
- Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
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50
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Cohen LE, Zanger K, Brue T, Wondisford FE, Radovick S. Defective retinoic acid regulation of the Pit-1 gene enhancer: a novel mechanism of combined pituitary hormone deficiency. Mol Endocrinol 1999; 13:476-84. [PMID: 10077004 DOI: 10.1210/mend.13.3.0251] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Pit-1 is a pituitary-specific transcription factor responsible for pituitary development and hormone expression in mammals. Pit-1 contains two protein domains, termed POU-specific and POU-homeo, which are both necessary for DNA binding and activation of the GH and PRL genes and regulation of the PRL, TSH-beta subunit (TSH-beta), and Pit-1 genes. Pit-1 is also necessary for retinoic acid induction of its own gene during development through a Pit-1-dependent enhancer. Combined pituitary hormone deficiency is caused by defective transactivation of target genes in the anterior pituitary. In the present report, we provide in vivo evidence that retinoic acid induction of the Pit-1 gene can be impaired by a Pit-1 gene mutation, suggesting a new molecular mechanism for combined pituitary hormone deficiency in man.
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Affiliation(s)
- L E Cohen
- Department of Medicine, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
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