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Jiménez-Díaz E, Del-Rio D, Fiordelisio T. The Contribution of Cell Imaging to the Study of Anterior Pituitary Function and Its Regulation. Neuroendocrinology 2023; 113:179-192. [PMID: 35231920 DOI: 10.1159/000523860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 02/18/2022] [Indexed: 11/19/2022]
Abstract
Advances in the knowledge of the neuroendocrine system are closely related to the development of cellular imaging and labeling techniques. This synergy ranges from the staining techniques that allowed the first characterizations of the anterior pituitary gland, its relationship with the hypothalamus, and the birth of neuroendocrinology; through the development of fluorescence microscopy applications, specific labeling strategies, transgenic systems, and intracellular calcium sensors that enabled the study of processes and dynamics at the cellular and tissue level; until the advent of super-resolution microscopy, miniscopes, optogenetics, fiber photometry, and other imaging methods that allowed high spatiotemporal resolution and long-term three-dimensional cellular activity recordings in living systems in a conscious and freely moving condition. In this review, we briefly summarize the main contributions of cellular imaging techniques that have allowed relevant advances in the field of neuroendocrinology and paradigm shifts that have improved our understanding of the function of the hypothalamic-pituitary axes. The development of these methods and equipment is the result of the integration of knowledge achieved by the integration of several disciplines and effort to solve scientific questions and problems of high impact on health and society that this system entails.
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Affiliation(s)
- Edgar Jiménez-Díaz
- Laboratorio de Neuroendocrinología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Laboratorio Nacional de Soluciones Biomiméticas para Diagnóstico y Terapia LaNSBioDyT, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Diana Del-Rio
- Laboratorio de Neuroendocrinología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Laboratorio Nacional de Soluciones Biomiméticas para Diagnóstico y Terapia LaNSBioDyT, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Tatiana Fiordelisio
- Laboratorio de Neuroendocrinología Comparada, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Laboratorio Nacional de Soluciones Biomiméticas para Diagnóstico y Terapia LaNSBioDyT, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Lines KE, Gluck AK, Thongjuea S, Bountra C, Thakker RV, Gorvin CM. The bromodomain inhibitor JQ1+ reduces calcium-sensing receptor activity in pituitary cell lines. J Mol Endocrinol 2021; 67:83-94. [PMID: 34223822 PMCID: PMC8345903 DOI: 10.1530/jme-21-0030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 07/05/2021] [Indexed: 12/05/2022]
Abstract
Corticotrophinomas represent 10% of all surgically removed pituitary adenomas, however, current treatment options are often not effective, and there is a need for improved pharmacological treatments. Recently, JQ1+, a bromodomain inhibitor that promotes gene transcription by binding acetylated histone residues and recruiting transcriptional machinery, has been shown to reduce proliferation in a murine corticotroph cell line, AtT20. RNA-Seq analysis of AtT20 cells following treatment with JQ1+ identified the calcium-sensing receptor (CaSR) gene as significantly downregulated, which was subsequently confirmed using real-time PCR and Western blot analysis. CaSR is a G protein-coupled receptor that plays a central role in calcium homeostasis but can elicit non-calcitropic effects in multiple tissues, including the anterior pituitary where it helps regulate hormone secretion. However, in AtT20 cells, CaSR activates a tumour-specific cAMP pathway that promotes ACTH and PTHrP hypersecretion. We hypothesised that the Casr promoter may harbour binding sites for BET proteins, and using chromatin immunoprecipitation (ChIP)-sequencing demonstrated that the BET protein Brd3 binds to the promoter of the Casr gene. Assessment of CaSR signalling showed that JQ1+ significantly reduced Ca2+e-mediated increases in intracellular calcium (Ca2+i) mobilisation and cAMP signalling. However, the CaSR-negative allosteric modulator, NPS-2143, was unable to reduce AtT20 cell proliferation, indicating that reducing CaSR expression rather than activity is likely required to reduce pituitary cell proliferation. Thus, these studies demonstrate that reducing CaSR expression may be a viable option in the treatment of pituitary tumours. Moreover, current strategies to reduce CaSR activity, rather than protein expression for cancer treatments, may be ineffective.
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Affiliation(s)
- Kate E Lines
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford,UK
- Correspondence should be addressed to K E Lines or C M Gorvin: or
| | - Anna K Gluck
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford,UK
| | - Supat Thongjuea
- Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Chas Bountra
- Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Rajesh V Thakker
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford,UK
| | - Caroline M Gorvin
- Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford,UK
- Institute of Metabolism and Systems Research and Centre for Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK
- Correspondence should be addressed to K E Lines or C M Gorvin: or
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Caputo M, Pigni S, Agosti E, Daffara T, Ferrero A, Filigheddu N, Prodam F. Regulation of GH and GH Signaling by Nutrients. Cells 2021; 10:1376. [PMID: 34199514 PMCID: PMC8227158 DOI: 10.3390/cells10061376] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 02/06/2023] Open
Abstract
Growth hormone (GH) and insulin-like growth factor-1 (IGF-I) are pleiotropic hormones with important roles in lifespan. They promote growth, anabolic actions, and body maintenance, and in conditions of energy deprivation, favor catabolic feedback mechanisms switching from carbohydrate oxidation to lipolysis, with the aim to preserve protein storages and survival. IGF-I/insulin signaling was also the first one identified in the regulation of lifespan in relation to the nutrient-sensing. Indeed, nutrients are crucial modifiers of the GH/IGF-I axis, and these hormones also regulate the complex orchestration of utilization of nutrients in cell and tissues. The aim of this review is to summarize current knowledge on the reciprocal feedback among the GH/IGF-I axis, macro and micronutrients, and dietary regimens, including caloric restriction. Expanding the depth of information on this topic could open perspectives in nutrition management, prevention, and treatment of GH/IGF-I deficiency or excess during life.
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Affiliation(s)
- Marina Caputo
- SCDU of Endocrinology, University Hospital Maggiore della Carità, 28100 Novara, Italy; (M.C.); (S.P.); (T.D.); (A.F.)
- Department of Health Sciences, Università del Piemonte Orientale, 28100 Novara, Italy;
| | - Stella Pigni
- SCDU of Endocrinology, University Hospital Maggiore della Carità, 28100 Novara, Italy; (M.C.); (S.P.); (T.D.); (A.F.)
| | - Emanuela Agosti
- Department of Health Sciences, Università del Piemonte Orientale, 28100 Novara, Italy;
| | - Tommaso Daffara
- SCDU of Endocrinology, University Hospital Maggiore della Carità, 28100 Novara, Italy; (M.C.); (S.P.); (T.D.); (A.F.)
| | - Alice Ferrero
- SCDU of Endocrinology, University Hospital Maggiore della Carità, 28100 Novara, Italy; (M.C.); (S.P.); (T.D.); (A.F.)
| | - Nicoletta Filigheddu
- Department of Translational Medicine, Università del Piemonte Orientale, 28100 Novara, Italy;
| | - Flavia Prodam
- SCDU of Endocrinology, University Hospital Maggiore della Carità, 28100 Novara, Italy; (M.C.); (S.P.); (T.D.); (A.F.)
- Department of Health Sciences, Università del Piemonte Orientale, 28100 Novara, Italy;
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Cheng Y, Chen T, Song J, Qi Q, Wang C, Xi Q, Liu S, Hao L, Zhang Y. miR-709 inhibits GHRP6 induced GH synthesis by targeting PRKCA in pituitary. Mol Cell Endocrinol 2020; 506:110763. [PMID: 32084499 DOI: 10.1016/j.mce.2020.110763] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 02/02/2020] [Accepted: 02/18/2020] [Indexed: 02/07/2023]
Abstract
Pituitary growth hormone (GH) plays an essential role in processes of organism growth and metabolism. MicroRNA (miRNA) could also participate in diverse biological processes. However, the role of miRNA in the regulation of pituitary GH during the growth process remains unclear. In this study, we firstly confirmed that the second highly expressed pituitary miRNA (miR-709) significantly inhibited the GH synthesis and suppressed the viability of GH3 cells. The bioinformatics analysis and dual luciferase report system were used to ascertain the PRKCA is the direct target gene of miR-709, which is the coding gene of PKCα. Then the transcription and translation levels of Prkca were obvious reduced by the over-expression of miR-709 in GH3 cells, followed by the inhibition of the transcription factor (CREB1) of Gh1 gene and the ERK1/2 signaling pathway or the possible cross-talk signaling pathway (cAMP/PKA signaling pathway) detected by western blot, suggesting that ERK1/2 maybe an important factor involved in the GH3 cell viability mediated by PKCα. At last, GHRP6 increased PKCα and GH expression but reduced miR-709 expression in vitro and vivo assays, and this conclusion was further confirmed by the result of GHRP6 attenuated the inhibition of miR-709 on GH expression. These findings will provide new molecular mechanism on the regulation of pituitary GH.
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Affiliation(s)
- Yunyun Cheng
- Guangdong Provincial Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, 483 Wushan Road, Guangzhou, 510642, China
| | - Ting Chen
- Guangdong Provincial Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, 483 Wushan Road, Guangzhou, 510642, China
| | - Jie Song
- Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, 5333 Xian Road, Changchun, 130062, China
| | - Qien Qi
- School of Life Science and Engineering, Foshan University, Foshan, 528231, China
| | - Chunli Wang
- Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, 5333 Xian Road, Changchun, 130062, China
| | - Qianyun Xi
- Guangdong Provincial Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, 483 Wushan Road, Guangzhou, 510642, China
| | - Songcai Liu
- Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, 5333 Xian Road, Changchun, 130062, China
| | - Linlin Hao
- Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, 5333 Xian Road, Changchun, 130062, China.
| | - Yongliang Zhang
- Guangdong Provincial Key Laboratory of Animal Nutritional Regulation, National Engineering Research Center for Breeding Swine Industry, Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, 483 Wushan Road, Guangzhou, 510642, China.
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Díaz-Soto G, Rocher A, García-Rodríguez C, Núñez L, Villalobos C. The Calcium-Sensing Receptor in Health and Disease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 327:321-369. [PMID: 27692178 DOI: 10.1016/bs.ircmb.2016.05.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The extracellular calcium-sensing receptor (CaSR) is a unique G protein-coupled receptor (GPCR) activated by extracellular Ca2+ and by other physiological cations including Mg2+, amino acids, and polyamines. CaSR is the most important master controller of the extracellular Ca2+ homeostatic system being expressed at high levels in the parathyroid gland, kidney, gut and bone, where it regulates parathyroid hormone (PTH) secretion, vitamin D synthesis, and Ca2+ absorption and resorption, respectively. Gain and loss of function mutations in the CaSR are responsible for severe disturbances in extracellular Ca2+ metabolism. CaSR agonists (calcimimetics) and antagonists (calcilytics) are in use or under intense research for treatment of hyperparathyroidism secondary to kidney failure and hypocalcemia with hypercalciuria, respectively. Expression of the CaSR extends to other tissues and systems beyond the extracellular Ca2+ homeostatic system including the cardiovascular system, the airways, and the nervous system where it may play physiological functions yet to be fully understood. As a consequence, CaSR has been recently involved in different pathologies including uncontrolled blood pressure, vascular calcification, asthma, and Alzheimer's disease. Finally, the CaSR has been shown to play a critical role in cancer either contributing to bone metastasis and/or acting as a tumor suppressor in some forms of cancer (parathyroid cancer, colon cancer, and neuroblastoma) and as oncogene in others (breast and prostate cancers). Here we review the role of CaSR in health and disease in calciotropic tissues and others beyond the extracellular calcium homeostatic system.
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Affiliation(s)
- G Díaz-Soto
- Endocrinology and Nutrition, Valladolid University Hospital, Valladolid, Spain
| | - A Rocher
- Department of Biochemistry and Molecular Biology and Physiology, University of Valladolid, Valladolid, Spain; Institute of Molecular Biology and Genetics (IBGM), University of Valladolid and National Research Council (CSIC), Valladolid, Spain
| | - C García-Rodríguez
- Institute of Molecular Biology and Genetics (IBGM), University of Valladolid and National Research Council (CSIC), Valladolid, Spain
| | - L Núñez
- Department of Biochemistry and Molecular Biology and Physiology, University of Valladolid, Valladolid, Spain; Institute of Molecular Biology and Genetics (IBGM), University of Valladolid and National Research Council (CSIC), Valladolid, Spain
| | - C Villalobos
- Institute of Molecular Biology and Genetics (IBGM), University of Valladolid and National Research Council (CSIC), Valladolid, Spain.
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Qi QE, Xi QY, Ye RS, Chen T, Cheng X, Li CY, Zhu XT, Shu G, Wang LN, Jiang QY, Zhang YL. Alteration of the miRNA expression profile in male porcine anterior pituitary cells in response to GHRH and CST and analysis of the potential roles for miRNAs in regulating GH. Growth Horm IGF Res 2015; 25:66-74. [PMID: 25613666 DOI: 10.1016/j.ghir.2014.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 11/27/2014] [Accepted: 12/01/2014] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Growth hormone releasing hormone (GHRH) is a major positive regulator of growth hormone (GH) in the anterior pituitary gland, while cortistatin's (CST) role is negative. miRNAs (microRNAs or miRs) are small RNA molecules modulating gene expression at the post-transcriptional level. However, little is known about the function of miRNAs in the regulation of GH synthesis and/or secretion. This study investigated potential functional miRNAs involved in GH secretion in the normal porcine pituitary. DESIGN Primary porcine anterior pituitary cells were cultivated and then treated with 10 nmol/L GHRH and 100 nmol/L CST, respectively. The effects of GHRH and CST on GH secretion were determined using RIA. miRNA microarrays were employed to analyze miRNA expression after treatment and then differentially expressed miRNAs were screened. Bioinformatics analysis was used to analyze the potential targets in growth hormone regulation of altered miRNAs. Furthermore, functional experiments were conducted to study the function of ssc-let-7c. RESULTS GHRH significantly promoted GH secretion, while CST suppressed GH secretion. 19 and 35 differentially expressed miRNAs were identified in response to GHRH and CST treatments respectively. Verification of 5 randomly selected miRNAs by quantitative real-time PCR (qRT-PCR) showed similar changes with microarray analysis. Target analysis showed that some miRNAs may be involved in GH secretion-related pathways. Importantly, ssc-let-7c was predicted to target GH1 and GHRHR mRNA 3'untranslated regions (3'UTRs), which was supported by luciferase reporter assay. Furthermore, functional experimental results showed that ssc-let-7c was involved in GH secretion regulation, and overexpression of ssc-let-7c inhibited GH secretion in porcine anterior pituitary cells. CONCLUSIONS GHRH and CST modulated porcine pituitary cell miRNA expression. Bioinformatics analysis revealed a complicated network among differentially expressed miRNAs, GH regulation-related genes and hormones. More interestingly, ssc-let-7c inhibited both GH1 and GHRHR mRNA 3'UTR reporter vectors' luciferase activity and overexpression of ssc-let-7c led to a decrease of GH secretion.
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Affiliation(s)
- Qi-En Qi
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China
| | - Qian-Yun Xi
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China
| | - Rui-Song Ye
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China
| | - Ting Chen
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China
| | - Xiao Cheng
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China
| | - Chao-Yun Li
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China
| | - Xiao-Tong Zhu
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China
| | - Gang Shu
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China
| | - Li-Na Wang
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China
| | - Qing-Yan Jiang
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China
| | - Yong-Liang Zhang
- Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agriculture University, Wushan Road, Guangzhou 510642, China.
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Chang JP, Habibi HR, Yu Y, Moussavi M, Grey CL, Pemberton JG. Calcium and other signalling pathways in neuroendocrine regulation of somatotroph functions. Cell Calcium 2011; 51:240-52. [PMID: 22137240 DOI: 10.1016/j.ceca.2011.11.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 11/01/2011] [Accepted: 11/07/2011] [Indexed: 12/22/2022]
Abstract
Relative to mammals, the neuroendocrine control of pituitary growth hormone (GH) secretion and synthesis in teleost fish involves numerous stimulatory and inhibitory regulators, many of which are delivered to the somatotrophs via direct innervation. Among teleosts, how multifactorial regulation of somatotroph functions are mediated at the level of post-receptor signalling is best characterized in goldfish. Supplemented with recent findings, this review focuses on the known intracellular signal transduction mechanisms mediating the ligand- and function-specific actions in multifactorial control of GH release and synthesis, as well as basal GH secretion, in goldfish somatotrophs. These include membrane voltage-sensitive ion channels, Na(+)/H(+) antiport, Ca(2+) signalling, multiple pharmacologically distinct intracellular Ca(2+) stores, cAMP/PKA, PKC, nitric oxide, cGMP, MEK/ERK and PI3K. Signalling pathways mediating the major neuroendocrine regulators of mammalian somatotrophs, as well as those in other major teleost study model systems are also briefly highlighted. Interestingly, unlike mammals, spontaneous action potential firings are not observed in goldfish somatotrophs in culture. Furthermore, three goldfish brain somatostatin forms directly affect pituitary GH secretion via ligand-specific actions on membrane ion channels and intracellular Ca(2+) levels, as well as exert isoform-specific action on basal and stimulated GH mRNA expression, suggesting the importance of somatostatins other than somatostatin-14.
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Affiliation(s)
- John P Chang
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
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Mamillapalli R, Wysolmerski J. The calcium-sensing receptor couples to Galpha(s) and regulates PTHrP and ACTH secretion in pituitary cells. J Endocrinol 2010; 204:287-97. [PMID: 20032198 PMCID: PMC3777408 DOI: 10.1677/joe-09-0183] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The calcium-sensing receptor (CaR or CASR as listed in the MGI Database) is a G protein-coupled receptor that binds and signals in response to extracellular calcium and other polycations. It is highly expressed on parathyroid and kidney cells, where it participates in the regulation of systemic calcium homeostasis. It is also expressed on many other cell types and is involved in a wide array of biological functions such as cell growth and differentiation, ion transport, and hormone secretion. It has been described to couple to several different G proteins including Galpha(i/0), Galpha(q/11), and Galpha(12/13). Recently, it has also been shown to stimulate cAMP production by coupling to Galpha(s) in immortalized or malignant breast cells. The CaR is expressed on cells in the anterior pituitary and had previously been described to stimulate cAMP production in these cells. In this report, we examined signaling from the CaR in murine pituitary corticotroph-derived, AtT-20 cells. We found that CaR activation led to the stimulation of cAMP production, and PTH-related protein (PTHrP or PTHLH as listed in the MGI Database) and ACTH secretion from these cells. Furthermore, manipulation of cAMP levels was able to modulate PTHrP and ACTH secretion independent of changes in extracellular calcium. Finally, we demonstrated that the CaR couples to Galpha(s) in AtT-20 cells. Therefore, in pituitary corticotroph-like cells, as in breast cancer cells, the CaR utilizes Galpha(s) and activates cAMP production to stimulate hormone secretion.
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Affiliation(s)
- Ramanaiah Mamillapalli
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, TAC S131, New Haven, Connecticut 06520-8020, USA
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Cecconi E, Bogazzi F, Morselli LL, Gasperi M, Procopio M, Gramaglia E, Broglio F, Giovannetti C, Ghigo E, Martino E. Primary hyperparathyroidism is associated with marked impairment of GH response to acylated ghrelin. Clin Endocrinol (Oxf) 2008; 69:197-201. [PMID: 18221398 DOI: 10.1111/j.1365-2265.2008.03188.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Impaired GH secretion is a common finding in patients with primary hyperparathyroidism (PHP). Ghrelin displays strong GH-releasing action, mainly at the hypothalamic level. OBJECTIVE To evaluate secretory response of GH to ghrelin in PHP patients. PATIENTS Fifteen patients [11 women/4 men, mean age 54 years, range 32-70 years, body mass index (BMI) 25.0 +/- 0.7 kg/m(2)] affected with PHP due to single parathyroid adenoma and 35 normal age-matched subjects (23 women/12 men, mean age 58 years, range 35-68 years, BMI 24.1 +/- 1.1 kg/m(2)). METHODS A measure of 1 microg/kg body weight i.v. acylated ghrelin or 1 microg/kg body weight i.v. GH releasing hormone (GHRH) followed by 0.5 g/kg body weight i.v. arginine (ARG) hydrochloride were administered to all subjects on alternate days in order to evaluate GH response. RESULTS Mean serum GH peak after GHRH + ARG was 32.6 +/- 7.8 and 17.4 +/- 4.0 microg/l, in controls and PHP patients, respectively (P < 0.05). Mean serum GH peak after ghrelin was 70.4 +/- 31.5 and 16.8 +/- 1.9 microg/l, in controls and PHP patients, respectively, (P < 0.001). Using ROC curves, a serum GH peak > 22 microg/l after ghrelin stimulation might be considered as a cut-off value for identifying normal subjects. Ten (67%) PHP patients have impaired GH response to GHRH + ARG and 13 (87%) to ghrelin. Serum GH peak after ghrelin or GHRH + ARG was unrelated to serum IGF-1, PTH or ionized calcium concentrations. CONCLUSIONS The present data confirm that GH secretion is impaired in PHP patients using the potent GH secretagogue ghrelin and suggest that impaired GH secretion is likely due to a deleterious effect of hypercalcaemia at the hypothalamic level in PHP patients.
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Affiliation(s)
- E Cecconi
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy
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10
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Breitwieser GE. Extracellular calcium as an integrator of tissue function. Int J Biochem Cell Biol 2008; 40:1467-80. [PMID: 18328773 PMCID: PMC2441573 DOI: 10.1016/j.biocel.2008.01.019] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 01/16/2008] [Accepted: 01/18/2008] [Indexed: 12/23/2022]
Abstract
The past several decades of research into calcium signaling have focused on intracellular calcium (Ca(i)(2+)), revealing both exquisite spatial and dynamic control of this potent second messenger. Our understanding of Ca(i)(2+) signaling has benefited from the evolution of cell culture methods, development of high affinity fluorescent calcium indicators (both membrane-permeant small molecules and genetically encoded proteins), and high-resolution fluorescence microscopy. As our understanding of single cell calcium dynamics has increased, translational efforts have attempted to push calcium signaling studies back into tissues, organs and whole animals. Emerging results from these more complicated, diffusion-limited systems have begun to define a role for extracellular calcium (Ca(o)(2+)) as an agonist, spurred by the cloning and characterization of a G protein-coupled receptor activated by Ca(o)(2+) (the calcium sensing receptor, CaR). Here, we review the current state-of-the art for measurement of Ca(o)(2+) fluctuations, and the evidence that fluctuations in Ca(o)(2+) can act as primary signals regulating cell function. Current results suggest that Ca(o)(2+) in bone and epidermis may act as a chemotactic homing signal, targeting cells to the appropriate tissue locations prior to initiation of the differentiation program. Ca(i)(2+) signaling-mediated Ca(o)(2+) fluctuations in interstitial spaces may integrate cell signaling responses in multicellular networks through activation of CaR. Appreciation of the importance of Ca(o)(2+) fluctuations in coordinating cell function will likely spur identification of additional, niche-specific Ca(2+) sensors, and provide unique insights into the regulation of multicellular signaling networks.
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Affiliation(s)
- Gerda E Breitwieser
- Weis Center for Research, Geisinger Clinic, 100 N. Academy Avenue, Danville, PA 17822, United States.
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Cecconi E, Gasperi M, Genovesi M, Bogazzi F, Grasso L, Procopio M, Marcocci C, Pinchera A, Bartalena L, Martino E. Growth hormone secretion in primary and secondary hyperparathyroidism. J Endocrinol Invest 2005; 28:113-6. [PMID: 15887855 DOI: 10.1007/bf03345352] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
Abstract
Primary hyperparathyroidism (PHP) is associated with impaired GH secretion. Whether this effect is due to hypercalcemia or to increased serum PTH concentration is unclear. However, patients with familial hypocalciuric hypercalcemia (FHH), who have normal PTH and increased serum calcium concentrations, also have an impaired GH secretion, suggesting that calcium rather than PTH is responsable for this effect on GH secretion. To further investigate this issue, 10 consecutive patients with secondary hyperparathyroidism (SHP) due to vitamin D deficiency were evaluated by the GH response to GHRH+arginine (Arg) test. A group of 60 consecutive untreated PHP patients served as controls. Mean GH response to GHRH+Arg test was 15.8+/-14 microg/l and 37.5+/-16 microg/l (p<0.001) in PHP and in SHP patients, respectively. Forty-two out of 60 (70%) PHP patients had a suppressed or blunted GH response, whereas all SHP patients had normal GH response. The results of the present study confirm and extend our previous observations that PHP is associated with an impaired GH secretion in the majority of cases, and indicate that SHP patients have no abnormality of GH secretion. Thus, hypercalcemia rather than increased serum PTH is responsible for the abnormality of GH secretion.
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Affiliation(s)
- E Cecconi
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy
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12
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Abstract
UNLABELLED PURPOSE OF VIEW: A major clinical trial and a meta-analysis completed within the past year addressed the issue of renal disease progression after blood pressure-lowering treatment in patients with hypertension and diminished renal function. Important human and animal studies have addressed mechanistic issues regarding renal disease progression. These advances warrant detailed discussion. RECENT FINDINGS The African American Study of Kidney Disease and Hypertension Study Group trial found that an angiotensin-converting enzyme inhibitor was superior to a calcium antagonist or beta-blocker in ameliorating renal disease progression in African-Americans. An attempt to show an advantage of lowering blood pressure to less than 130/80 compared with 140/90 mmHg showed no additional benefit. However, a meta-analysis of 2000 non-diabetic hypertensive patients suggested that lower blood pressures are beneficial, particularly in individuals with proteinuria. An autopsy study of hypertensive and normotensive individuals dying in motor vehicle accidents supported the theory that hypertensive individuals have fewer, albeit larger, glomeruli than normotensive individuals. An animal study in sheep showed similar findings in sheep born to dams given dexamethasone compared with placebo. Animal studies involving stress, immunity, and cytokines shed further light on the mechanisms. The transfer of Smad7 ameliorated renal damage in rats with ureteral obstruction and fibrosis. SUMMARY Guidelines suggest prescribing angiotensin-converting enzyme inhibitor or angiotensin 1 receptor blocker therapy to all patients with decreased renal function and hypertension with or without diabetes. The possibility that essential hypertension involves reduced glomerular numbers received support, as well as the theory of prenatal imprinting. Progress is being made regarding basic mechanisms and novel therapies.
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Affiliation(s)
- Friedrich C Luft
- Franz Volhard Clinic, Medical Faculty of the Charité, HELIOS Klinikum, Berlin, Germany.
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13
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Affiliation(s)
- Friedrich C Luft
- Franz Volhard Clinic, HELIOS Klinikum, Medical Faculty of the Charité, Humboldt University of Berlin, Wiltberg Strasse 50, 13125 Berlin, Germany.
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van den Hurk MJJ, Ouwens DTWM, Scheenen WJJM, Limburg V, Gellekink H, Bai M, Roubos EW, Jenks BG. Expression and characterization of the extracellular Ca(2+)-sensing receptor in melanotrope cells of Xenopus laevis. Endocrinology 2003; 144:2524-33. [PMID: 12746315 DOI: 10.1210/en.2003-0014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The extracellular Ca(2+)-sensing receptor (CaR) is expressed in many different organs in various species, ranging from mammals to fish. In some of these organs, this G protein-coupled receptor is involved in the control of systemic Ca(2+) homeostasis, whereas in other organs its role is unclear (e.g. in the pituitary gland). We have characterized the CaR in the neuroendocrine melanotrope cell of the intermediate pituitary lobe of the South African clawed toad Xenopus laevis. First, the presence of CaR mRNA was demonstrated by RT-PCR and in situ hybridization. Then it was shown that activation of the CaR by an elevated extracellular Ca(2+) concentration and different CaR-activators, including L-phenylalanine and spermine, stimulates both Ca(2+) oscillations and secretion from the melanotrope. Furthermore, it was revealed that activation of the receptor stimulates Ca(2+) oscillations through opening of voltage-operated Ca(2+) channels in the plasma membrane of the melanotropes. Finally, it was shown that the CaR activator L-phenylalanine could induce the biosynthesis of proopiomelanocortin in the intermediate lobe. Thus, in this study it is demonstrated that the CaR is present and functional in a defined cell type of the pituitary gland, the amphibian melanotrope cell.
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Affiliation(s)
- M J J van den Hurk
- Department of Cellular Animal Physiology, Institute of Cellular Signalling, Nijmegen Institute for Neurosciences, University of Nijmegen, 6525 ED Nijmegen, The Netherlands.
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