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Zhao W, Yuan T, Fu Y, Niu D, Chen W, Chen L, Lu L. Seasonal differences in the transcriptome profile of the Zhedong white goose (Anser cygnoides) pituitary gland. Poult Sci 2020; 100:1154-1166. [PMID: 33518074 PMCID: PMC7858147 DOI: 10.1016/j.psj.2020.10.049] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 10/15/2020] [Accepted: 10/19/2020] [Indexed: 11/30/2022] Open
Abstract
In animals, the adaptation to breed at the time of greatest survival of the young is known as seasonal reproduction. This is mainly controlled by the photoperiod, which stimulates the hypothalamic-pituitary-gonadal axis and starts the breeding season. Herein, we have determined the seasonal changes in gene expression patterns of Zhedong white geese pituitary glands under a natural photoperiodism, conducted at autumn equinox (AE), winter solstice (WS), spring equinox (SE), and summer solstice (SS). Pairwise comparisons of WS vs. AE, SE vs. WS, SS vs. SE, and AE vs. SS resulted in 1,139, 33, 704, and 3,503 differently expressed genes, respectively. When compared with SS, AE showed downregulation of genes, such as vasoactive intestinal peptide receptor, prolactin receptor, and thyroid hormone receptor beta, whereas gonadotropin-releasing hormone II receptor was upregulated, indicating that these genes may be responsible for the transition from cessation to egg laying. In addition, the expression levels of 5 transcription factors (POU1F1, Pitx2, NR5A1, NR4A2, and SREBF2) and 6 circadian clock-associated genes (Clock, Per2, ARNTL2, Eya3, Dio2, and NPAS2) also changed seasonally. Gene Ontology term and Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that “response to oxidative stress” and steroid biosynthesis pathway also participate in regulating the reproduction seasonality of geese. Overall, these results contribute to the identification of genes involved in seasonal reproduction, enabling a better understanding of the molecular mechanism underlying seasonal reproduction of geese.
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Affiliation(s)
- Wanqiu Zhao
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Taoyan Yuan
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Yan Fu
- College of Animal Sciences, Zhejiang University, Hangzhou 310058, China
| | - Dong Niu
- College of Animal Science and Technology, Zhejiang A&F University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, Hangzhou 311300, Zhejiang, China
| | - Weihu Chen
- Department of Animal Husbandry and Veterinary, Xiangshan County Agricultural and Rural Bureau, Ningbo 315700, China
| | - Li Chen
- Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China
| | - Lizhi Lu
- Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China.
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The syndrome of central hypothyroidism and macroorchidism: IGSF1 controls TRHR and FSHB expression by differential modulation of pituitary TGFβ and Activin pathways. Sci Rep 2017; 7:42937. [PMID: 28262687 PMCID: PMC5338029 DOI: 10.1038/srep42937] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 01/18/2017] [Indexed: 12/22/2022] Open
Abstract
IGSF1 (Immunoglobulin Superfamily 1) gene defects cause central hypothyroidism and macroorchidism. However, the pathogenic mechanisms of the disease remain unclear. Based on a patient with a full deletion of IGSF1 clinically followed from neonate to adulthood, we investigated a common pituitary origin for hypothyroidism and macroorchidism, and the role of IGSF1 as regulator of pituitary hormone secretion. The patient showed congenital central hypothyroidism with reduced TSH biopotency, over-secretion of FSH at neonatal minipuberty and macroorchidism from 3 years of age. His markedly elevated inhibin B was unable to inhibit FSH secretion, indicating a status of pituitary inhibin B resistance. We show here that IGSF1 is expressed both in thyrotropes and gonadotropes of the pituitary and in Leydig and germ cells in the testes, but at very low levels in Sertoli cells. Furthermore, IGSF1 stimulates transcription of the thyrotropin-releasing hormone receptor (TRHR) by negative modulation of the TGFβ1-Smad signaling pathway, and enhances the synthesis and biopotency of TSH, the hormone secreted by thyrotropes. By contrast, IGSF1 strongly down-regulates the activin-Smad pathway, leading to reduced expression of FSHB, the hormone secreted by gonadotropes. In conclusion, two relevant molecular mechanisms linked to central hypothyroidism and macroorchidism in IGSF1 deficiency are identified, revealing IGSF1 as an important regulator of TGFβ/Activin pathways in the pituitary.
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Brigante G, Spaggiari G, Santi D, Cioni K, Gnarini V, Diazzi C, Pignatti E, Casarini L, Marino M, Tüttelmann F, Carani C, Simoni M. The TRHR Gene Is Associated with Hypothalamo-Pituitary Sensitivity to Levothyroxine. Eur Thyroid J 2014; 3:101-8. [PMID: 25114873 PMCID: PMC4109513 DOI: 10.1159/000358590] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/13/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Thyroidectomized patients need variable doses of levothyroxine (LT4) to obtain target thyroid-stimulating hormone (TSH) levels. Individual feedback set-points have been hypothesized and the influence of several genes in the regulation of the pituitary-thyroid axis has been demonstrated. OBJECTIVES We hypothesized that genetic variants of the TRHR gene could be associated with a different hypothalamo-pituitary sensitivity to thyroid hormone feedback. METHODS We retrospectively analyzed 84 thyroidectomized patients with no residual thyroid function and undetectable thyroglobulin levels. Patients were evaluated under LT4 resulting in TSH levels detectable but <0.5 μIU/ml. The two SNPs rs3134105 and rs3110040 were identified as informative markers of the TRHR gene. Genotyping was performed using high-resolution melting technology. Genotype distribution was compared between the patients and 99 euthyroid controls. RESULTS The selected SNPs were in linkage disequilibrium and only rs3134105 was further considered. A significant difference between the three possible genotypes for rs3134105 was found for TSH (p = 0.04) and free thyroxine (fT4)/TSH ratio (p = 0.02). Moreover, despite similar serum concentrations of free triiodothyronine (fT3) and fT4, carriers of at least one A allele of rs3134105 had significantly lower serum TSH levels (p = 0.01) as well as higher fT3/TSH (p = 0.01) and fT4/TSH ratios (p < 0.01). CONCLUSIONS We demonstrated an association between serum TSH levels and discrete alleles of the TRHR gene in totally thyroidectomized patients under LT4 therapy. Therefore, the TRHR gene seems to be a determinant of hypothalamo-pituitary sensitivity to LT4.
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Affiliation(s)
- Giulia Brigante
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Azienda USL, Modena, Italy
| | - Giorgia Spaggiari
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Azienda USL, Modena, Italy
| | - Daniele Santi
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Azienda USL, Modena, Italy
| | - Katia Cioni
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Azienda USL, Modena, Italy
| | - Valentina Gnarini
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Azienda USL, Modena, Italy
| | - Chiara Diazzi
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Azienda USL, Modena, Italy
| | - Elisa Pignatti
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Center of Genomic Research, University of Modena and Reggio Emilia, Modena, Italy
| | - Livio Casarini
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Center of Genomic Research, University of Modena and Reggio Emilia, Modena, Italy
| | - Marco Marino
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Center of Genomic Research, University of Modena and Reggio Emilia, Modena, Italy
| | - Frank Tüttelmann
- Institute of Human Genetics, University of Munster, Munster, Germany
| | - Cesare Carani
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Azienda USL, Modena, Italy
| | - Manuela Simoni
- Unit of Endocrinology and Metabolism, Department of Biomedical, Metabolic and Neural Sciences, Modena, Italy
- Center of Genomic Research, University of Modena and Reggio Emilia, Modena, Italy
- Azienda USL, Modena, Italy
- *Manuela Simoni, MD, PhD, Unit of Endocrinology and Metabolism, Nuovo Ospedale S. Agostino Estense, Via Giardini 1355, IT-41125 Modena (Italy), E-Mail
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Jiang X, Cai Z, Zhao X, Zhang L, Chen Z, Wang Y, Guo X, Xu N. Mapping, CDNA Cloning and Tissue Expression of the Porcine Thyrotropin-Releasing Hormone Receptor Gene. Anim Biotechnol 2011; 22:30-6. [DOI: 10.1080/10495398.2011.547745] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Howard PW, Jue SF, Maurer RA. Expression of the synaptotagmin I gene is enhanced by binding of the pituitary-specific transcription factor, POU1F1. Mol Endocrinol 2009; 23:1563-71. [PMID: 19608642 DOI: 10.1210/me.2009-0111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The POU1F1 transcription factor (also known as Pit-1/GHF1) is required for development of pituitary cells that secrete prolactin, GH, and TSH. Presumably, POU1F1 regulates the expression of multiple genes required for expansion and differentiation of these pituitary cell lineages. However, only a few genes regulated by POU1F1 have been identified. In the present studies we have identified synaptotagmin I (Syt1) as a target gene for POU1F1 in GH(3) pituitary cells. Chromatin immunoprecipitation assays have provided evidence that POU1F1 binds close to the Syt1 exon that contains the initiation codon. Although this exon has previously been considered to be located far from the transcription initiation site, transcript mapping in GH(3) cells indicates that Syt1 mRNA synthesis is initiated close to the mapped POU1F1-binding site. POU1F1 knockdown studies using a short hairpin RNA vector have provided evidence that POU1F1 plays a role in stimulating expression of the endogenous Syt1 gene. Transfection studies with a Syt1-luciferase reporter gene are consistent with the presence of an internal, POU1F1-regulated promoter in the Syt1 gene. In vitro binding studies have provided further evidence for a POU1F1-binding site within this region of the Syt1 gene. Overall the studies provide evidence that Syt1 is a target gene regulated by POU1F1 in GH(3) pituitary cells. Because SYT1 has been extensively studied as an important transducer of Ca(2+) signaling in regulated secretion, it seems likely that activation of Syt1 gene expression is part of a mechanism mediating POU1F-induced differentiation of pituitary cells.
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Affiliation(s)
- Paul W Howard
- Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, Oregon 97239, USA
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Fjeldheim AK, Høvring PI, Løseth OP, Johansen PW, Glover JC, Matre V, Olstad OK, Reppe S, Gordeladze JO, Walaas SI, Gautvik KM. Thyrotrophin-releasing hormone receptor 1 and prothyrotrophin-releasing hormone mRNA expression in the central nervous system are regulated by suckling in lactating rats. Eur J Endocrinol 2005; 152:791-803. [PMID: 15879366 DOI: 10.1530/eje.1.01902] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND The accepted function of the hypothalamic peptide, thyrotrophin-releasing hormone (TRH), is to initiate release of thyrotrophin (TSH) from the pituitary. A physiological role for TRH in lactating rats has not yet been established. METHODS Tissues were prepared from random-cycling and lactating rats and analysed using Northern blot, real time RT-PCR and quantitative in situ hybridisation. RESULTS This study demonstrates that TRH receptor 1 (TRHR1) mRNA expression is up-regulated in the pituitary and in discrete nuclei of the hypothalamus in lactating rats, while proTRH mRNA expression levels are increased only in the hypothalamus. The results were corroborated by quantitative in situ analysis of proTRH and TRHR1. Bromocriptine, which reduced prolactin (PRL) concentrations in plasma of lactating and nursing rats, also counteracted the suckling-induced increase in TRHR1 mRNA expression in the hypothalamus, but had an opposite effect in the pituitary. These changes were confined to the hypothalamus and the amygdala in the brain. CONCLUSIONS The present study shows that the mechanisms of suckling-induced lactation involve region-specific regulation of TRHR1 and proTRH mRNAs in the central nervous system notably at the hypothalamic level. The results demonstrate that continued suckling is critical to maintain plasma prolactin (PRL) levels as well as proTRH and TRHR1 mRNA expression in the hypothalamus. Increased plasma PRL levels may have a positive modulatory role on the proTRH/TRHR1 system during suckling.
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Affiliation(s)
- Ase-Karine Fjeldheim
- Institute of Basic Medical Science, Department of Biochemistry, University of Oslo, PO Box 1112 Blindern, N-0317 Oslo, Norway
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Matre V, Høvring PI, Fjeldheim AK, Helgeland L, Orvain C, Andersson KB, Gautvik KM, Gabrielsen OS. The human neuroendocrine thyrotropin-releasing hormone receptor promoter is activated by the haematopoietic transcription factor c-Myb. Biochem J 2003; 372:851-9. [PMID: 12628004 PMCID: PMC1223435 DOI: 10.1042/bj20030057] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2003] [Revised: 03/03/2003] [Accepted: 03/10/2003] [Indexed: 01/14/2023]
Abstract
Thyrotropin-releasing hormone (TRH) receptor (TRHR) is a G-protein-coupled receptor playing a crucial role in the anterior pituitary where it controls the synthesis and secretion of thyroid-stimulating hormone and prolactin. Its widespread presence not only in the central nervous system, but also in peripheral tissues, including thymus, indicates other important, but unknown, functions. One hypothesis is that the neuropeptide TRH could play a role in the immune system. We report here that the human TRHR promoter contains 11 putative response elements for the haematopoietic transcription factor c-Myb and is highly Myb-responsive in transfection assays. Analysis of Myb binding to putative response elements revealed one preferred binding site in intron 1 of the receptor gene. Transfection studies of promoter deletions confirmed that this high-affinity element is necessary for efficient Myb-dependent transactivation of reporter plasmids in CV-1 cells. The Myb-dependent activation of the TRHR promoter was strongly suppressed by expression of a dominant negative Myb-Engrailed fusion. In line with these observations, reverse transcriptase PCR analysis of rat tissues showed that the TRHR gene is expressed both in thymocytes and bone marrow. Furthermore, specific, high-affinity TRH agonist binding to cell-surface receptors was demonstrated in thymocytes and a haematopoietic cell line. Our findings imply a novel functional link between the neuroendocrine and the immune systems at the level of promoter regulation.
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Affiliation(s)
- Vilborg Matre
- Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, Norway.
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Kim K, Arai K, Sanno N, Teramoto A, Shibasaki T. The expression of thyrotrophin-releasing hormone receptor 1 messenger ribonucleic acid in human pituitary adenomas. Clin Endocrinol (Oxf) 2001; 54:309-16. [PMID: 11298082 DOI: 10.1046/j.1365-2265.2001.01237.x] [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: 11/20/2022]
Abstract
OBJECTIVE Thyrotrophin-releasing hormone (TRH) paradoxically induces the release of growth hormone (GH) when injected intravenously into acromegalic patients, although the mechanism of this action is unknown at present. Several research groups have reported that the level of TRH receptor-1 (TRHR-1) mRNA expression is variable in pituitary adenomas, and does not correlate with the degree of paradoxical GH response to TRH administration in a limited number of acromegalic patients. We aimed to compare the expression levels of TRHR-1 mRNA among various types of pituitary adenoma and to clarify whether these levels correlate with the degree of pituitary hormone response to TRH. PATIENTS Pituitary adenoma tissue was obtained by surgery from 14 patients with acromegaly, four with prolactinomas, nine with nonfunctioning adenomas and one with a TSH-producing adenoma. METHODS The level of human TRHR-1 mRNA expression in each adenoma was quantified using the competitive reverse transcription polymerase chain reaction (RT-PCR) METHOD: For amplification of a TRHR-1 cDNA fragment, a sense primer was designed according to the sequence in exon 2 and an antisense primer designed according to the sequence located at the region in exon 3 that does not encode for the alternative splicing-generated short form of TRHR-1 mRNA. RESULTS TRHR-1 mRNA was detected in all pituitary adenomas examined and did not correlate with their size. The mean level of TRHR-1 mRNA expression was significantly lower in GH-producing adenomas than in prolactinomas and nonfunctioning adenomas (1.4 +/- 0.4 x 10(-2) attomol/microg total RNA, 10.7 3.4 x 10(-2) attomol/microg total RNA, and 7.2 +/- 3.3 x 10(-2) attomol/g total RNA, respectively). The ratio of plasma peak GH induced by TRH administration to the basal level of plasma GH in the patients with acromegaly correlated positively with the level of TRHR-1 mRNA expression in their GH-producing adenomas (r = 0.620, P = 0.0179). The responsiveness of plasma PRL and gonadotrophin to TRH in the patients with prolactinoma and nonfunctioning pituitary adenoma did not significantly correlate with the levels of TRHR-1 mRNA expression in their pituitary adenomas, respectively. CONCLUSIONS The findings of the present study suggest that the level of TRHR-1 mRNA expression varies among different types of pituitary adenoma. Furthermore, in acromegaly, the responsiveness of plasma GH to TRH administration appears to at least partially depend on the level of TRHR-1 mRNA expression in the GH-producing pituitary adenoma.
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Affiliation(s)
- K Kim
- Department of Physiology, Nippon Medical School, Tokyo, Japan. Kim_Kyongsong/
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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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Harvey S, Azumaya Y, Hull KL. Pituitary and extrapituitary growth hormone: Pit-1 dependence? Can J Physiol Pharmacol 2000. [DOI: 10.1139/y00-095] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Growth hormone (GH) is primarily produced in pituitary somatotrophs. The synthesis of this hormone is thought to be dependent upon a pituitary-specific transcription factor (Pit-1). However, many extrapituitary tissues are now known to express GH genes. The extrapituitary production of GH may therefore indicate an extrapituitary distribution of the Pit-1 gene. The extrapituitary production of GH may, alternatively, indicate that GH expression occurs independently of Pit-1 in extrapituitary tissues. These possibilities are considered in this brief review.Key words: growth hormone, pituitary, pituitary transcription factor 1.
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Abstract
Advances related to thyrotropin during 1999 included better understanding of the genetic basis of pituitary development and genetic advances in identifying clinical entities and their mechanisms and enabling new therapies. Initial clinical use of recombinant thyrotropin in evaluation of thyroid cancer recurrence was described. The importance of glycosylation pattern was clarified including the role of thyrotropin-releasing hormone in synthesis of thyrotropin molecules with mature glycosylation, and the impact of abnormal glycosylation in loss-of-function and gain-of-function mutations of the thyrotropin receptor. Causes of excessive thyrotropin secretion were evaluated, including pituitary thyrotropin-secreting adenomas. The fairly common causes of central hypothyroidism including ischemic injury, cranial irradiation, psychiatric conditions, or medical illness were assessed. The action of thyrotropin at the thyroid cell was assessed as a growth factor and as an influence on tyrosine sulfate content of thyroglobulin. Such basic and clinical science advances are rapidly affecting clinical care.
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Affiliation(s)
- S R Rose
- University of Tennessee Health Science Center, Memphis, USA.
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Abstract
Central hypothyroidism, characterized by insufficient TSH secretion in the presence of low levels of thyroid hormones, is a rare disorder. It has recently been found that, although mainly due to tumors or infiltrative diseases of the hypothalamo-pituitary area or to pituitary atrophy, central hypothyroidism may be caused by inactivating mutations in several of the genes that code for the various proteins involved in the regulation of the hypothalamo-pituitary-thyroid axis (HPTA). These experiments of nature allow us to better understand the pathophysiology but also the normal physiology of the HPTA. This review will analyze reports of mutations that affect the HPTA and result in either isolated central hypothyroidism or in the syndrome of combined pituitary hormone deficiency (CPHD). Mutations have been identified in the genes for the TRH receptor, the transcription factors Pit-1 and PROP1, and the TSH beta-subunit.
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Affiliation(s)
- R Collu
- Division of Endocrinology, University of Ancona, Torrette Hospital, Italy
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Høvring PI, Matre V, Fjeldheim AK, Loseth OP, Gautvik KM. Transcription of the human thyrotropin-releasing hormone receptor gene-analysis of basal promoter elements and glucocorticoid response elements. Biochem Biophys Res Commun 1999; 257:829-34. [PMID: 10208868 DOI: 10.1006/bbrc.1999.0545] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The gene for the human thyrotropin-releasing hormone receptor (TRHR) spans 35 kb and contains three exons and two introns (Matre et al. (1999) J. Neurochem. 72, 1-11). Despite a reported transcription start site (TSS) mapped to position -885 upstream of the translation initiation codon (Iwasaki et al. (1996) J. Biol. Chem. 271, 22183-8), we found cell type specific promoter activity directed by a fragment downstream of this site (-770 to +1). To elucidate the basis for this unexpected activity, we analyzed basal promoter elements in this region of the gene. One divergent TATA box, TTTAAA in position -759, was found by mutational analysis to be critical for promoter activity, providing a likely explanation for the basal activity observed. This proximal region apparently contains several promoter elements, including Pit-1 binding sequences within the first intron of the TRHR gene as previously reported. Here we describe the analysis of two putative glucocorticoid response elements (GREs) that we identified in this region, one (distal) half site overlapping the proposed TSS at -885 and one (proximal) full site within the first intron at position -624. Accordingly, stimulation of rat pituitary GH3 and GH4C1 cells with dexamethasone strongly enhanced transcription activity of a reporter construct containing the distal GRE half site and the proximal GRE site. Both sites bound the glucocorticoid receptor (GR) in a specific manner. Deletion of the distal GRE half site abolished the dexamethasone induction of CAT transcription, as did mutations in the proximal site. We therefore conclude that both sites are necessary for regulation of the TRHR gene transcription by glucocorticoids.
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Affiliation(s)
- P I Høvring
- Institute of Medical Biochemistry, University of Oslo, Blindern, Oslo, 0317, Norway.
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