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Chen Z, Peeters RP, Leeuwenburgh S, Broekhuizen M, Neuman RI, Hitzerd E, Tan L, Jongejan RMS, de Rijke YB, Reiss IKM, Danser AHJ, Visser WE, Meima ME. Asymmetrical Transport of Thyroxine Across Human Term Placenta. Thyroid 2023; 33:625-631. [PMID: 36416258 DOI: 10.1089/thy.2022.0406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Background: Fetal development is crucially dependent on thyroid hormone (TH). Maternal-to-fetal transfer of TH is a prerequisite for fetal TH availability, particularly in the first half of pregnancy. The mechanisms of transplacental transport of TH, however, are yet poorly understood. We, therefore, investigated the TH transport processes across human placentas using an ex vivo perfusion system. Methods: Intact cotyledons from term placentas of uncomplicated pregnancies were cannulated within 30 minutes after delivery and the maternal and fetal circulations were re-established. One hundred nanomolar thyroxine (T4) was added to either the maternal or fetal circulation and perfusions run up to three hours during which samples were taken from both circulations at different time points. Variables included addition of iopanoic acid (IOP) to block activity of the deiodinase type 3 (D3) and bovine serum albumin (BSA) to trap released T4. T4 and 3,3',5'-triiodothyronine concentrations in the perfusates were measured by radioimmunoassays. Results: Maternal-to-fetal transfer was slow, with T4 barely detectable in the fetal circulation unless D3 was blocked by IOP. Fetal T4 was detected after three hours perfusion (10.6 ± 0.6 nM) when BSA (34 g/L) was added in the fetal circulation to trap the released T4. In contrast, fetal-to-maternal transfer of T4 was rapid and maternal T4 increased to 43.6 ± 5.5 nM. Conclusions: Maternal-to-fetal T4 transport is limited, whereas fetal-to-maternal transport is rapid indicating that T4 transport across human term placenta is an asymmetrical process. With the high D3 activity, our observations are compatible with a protective role of the placental barrier. Future studies should reveal how the placenta exerts its gatekeeper function in ensuring optimal TH passage to the fetus.
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Affiliation(s)
- Zhongli Chen
- Department of Internal Medicine, Academic Center for Thyroid Diseases; Department of Internal Medicine; Erasmus MC, Rotterdam, The Netherlands
| | - Robin P Peeters
- Department of Internal Medicine, Academic Center for Thyroid Diseases; Department of Internal Medicine; Erasmus MC, Rotterdam, The Netherlands
| | - Selmar Leeuwenburgh
- Department of Internal Medicine, Academic Center for Thyroid Diseases; Department of Internal Medicine; Erasmus MC, Rotterdam, The Netherlands
| | - Michelle Broekhuizen
- Division of Pharmacology and Vascular Medicine, Department of Internal Medicine; Erasmus MC, Rotterdam, The Netherlands
- Division of Neonatology, Department of Pediatrics; Erasmus MC, University Medical Center, Rotterdam, The Netherlands
- Division of Experimental Cardiology, Department of Cardiology; Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Rugina I Neuman
- Division of Pharmacology and Vascular Medicine, Department of Internal Medicine; Erasmus MC, Rotterdam, The Netherlands
- Division of Neonatology, Department of Pediatrics; Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Emilie Hitzerd
- Division of Pharmacology and Vascular Medicine, Department of Internal Medicine; Erasmus MC, Rotterdam, The Netherlands
- Division of Neonatology, Department of Pediatrics; Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Lunbo Tan
- Division of Pharmacology and Vascular Medicine, Department of Internal Medicine; Erasmus MC, Rotterdam, The Netherlands
| | - Rutchanna M S Jongejan
- Department of Clinical Chemistry; Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Yolanda B de Rijke
- Department of Clinical Chemistry; Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Irwin K M Reiss
- Department of Pediatrics, Division of Neonatology, Erasmus MC-Sophia, Rotterdam, The Netherlands
| | - A H Jan Danser
- Division of Pharmacology and Vascular Medicine, Department of Internal Medicine; Erasmus MC, Rotterdam, The Netherlands
| | - W Edward Visser
- Department of Internal Medicine, Academic Center for Thyroid Diseases; Department of Internal Medicine; Erasmus MC, Rotterdam, The Netherlands
| | - Marcel E Meima
- Department of Internal Medicine, Academic Center for Thyroid Diseases; Department of Internal Medicine; Erasmus MC, Rotterdam, The Netherlands
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Corsi A, Cherman N, Donaldson DL, Robey PG, Collins MT, Riminucci M. Neonatal McCune-Albright Syndrome: A Unique Syndromic Profile With an Unfavorable Outcome. JBMR Plus 2019; 3:e10134. [PMID: 31485549 PMCID: PMC6715781 DOI: 10.1002/jbm4.10134] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 11/17/2018] [Accepted: 11/28/2018] [Indexed: 12/26/2022] Open
Abstract
Somatic gain‐of‐function mutations of GNAS cause a spectrum of clinical phenotypes, ranging from McCune‐Albright syndrome (MAS) to isolated disease of bone, endocrine glands, and more rarely, other organs. In MAS, a syndrome classically characterized by polyostotic fibrous dysplasia (FD), café‐au‐lait (CAL) skin spots, and precocious puberty, the heterogenity of organ involvement, age of onset, and clinical severity of the disease are thought to reflect the variable size and the random distribution of the mutated cell clone arising from the postzygotic mutation. We report a case of neonatal MAS with hypercortisolism and cholestatic hepatobiliary dysfunction in which bone changes indirectly emanating from the disease genotype, and distinct from FD, led to a fatal outcome. Pulmonary embolism of marrow and bone fragments secondary to rib fractures was the immediate cause of death. Ribs, and all other skeletal segments, were free of changes of typical FD and fractures appeared to be the result of a mild‐to‐moderate degree of osteopenia. The mutated allele was abundant in the adrenal glands and liver, but not in skin, muscle, and fractured ribs, where it could only be demonstrated using a much more sensitive PNA hybridization probe‐based FRET (Förster resonance energy transfer) technique. Histologically, bilateral adrenal hyperplasia and cholestatic disease matched the abundant disease genotype in the adrenals and liver. Based on this case and other sporadic reports, it appears that gain‐of‐function mutations of GNAS underlie a unique syndromic profile in neonates characterized by CAL skin spots, hypercortisolism, hyperthyroidism, hepatic and cardiac dysfunction, and an absence (or latency) of FD, often with a lethal outcome. Taken together, our and previous cases highlight the phenotypic severity and the diagnostic and therapeutic challenges of MAS in neonates. Furthermore, our case specifically points out how secondary bone changes, unrelated to the direct impact of the mutation, may contribute to the unfavorable outcome of very early‐onset MAS. © 2018 The Authors JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
| | - Natasha Cherman
- Skeletal Biology SectionNational Institute of Dental and Craniofacial ResearchNational Institutes of HealthBethesdaMDUSA
| | - David L Donaldson
- Department of PediatricsUniversity of Utah, School of MedicineSalt Lake CityUTUSA
| | - Pamela G Robey
- Skeletal Biology SectionNational Institute of Dental and Craniofacial ResearchNational Institutes of HealthBethesdaMDUSA
| | - Michael T Collins
- Skeletal Disorders and Mineral Homeostasis SectionNational Institute of Dental and Craniofacial ResearchNational Institutes of HealthBethesdaMDUSA
| | - Mara Riminucci
- Department of Molecular MedicineSapienza UniversityRomeItaly
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3
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Abstract
INTRODUCTION Acromegaly is a rare disease that severely impacts patients' health all the while, being a slowly progressing illness. In the past decades, advancements in treatment modalities, especially development of new drugs, as well as focused guidelines has improved management of acromegaly. Still, many patients are considered not sufficiently treated and there remains an ongoing need for further development. AREAS COVERED This article reviews new medical treatments currently under clinical investigation (such as pasireotide, oral octreotide and somatoprim) and under experimental development (such as octreotide implants, CAM2029 and ATL-1103). EXPERT OPINION As it seems unlikely that one single agent may achieve cure in 100% of cases, there is an urgent need for new agents that help patients where current medication fails. Imperatively, this means we have to improve our understanding of the underlying pathogenetic and molecular mechanisms.
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Affiliation(s)
- Sylvère Störmann
- Klinikum der Universität München, Medizinische Klinik und Poliklinik IV , Ziemssenstr. 1, 80336 München , Germany +49 0 89 5160 2111 ; +49 0 89 5160 2194 ;
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4
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Takano K, Yasufuku-Takano J, Morita K, Mori S, Takei M, Osamura RY, Teramoto A, Fujita T. Evidence that PKA activity is constitutively activated in human GH-secreting adenoma cells in a patient with Carney complex harbouring a PRKAR1A mutation. Clin Endocrinol (Oxf) 2009; 70:769-75. [PMID: 19178533 DOI: 10.1111/j.1365-2265.2008.03457.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CONTEXT The GHRH-protein kinase A (PKA) signalling pathway is essential for cell proliferation and GH synthesis/secretion in somatotrophs. An inactivating mutation of PRKAR1A is one of the causes of somatotrophinoma in Carney complex (CNC). The basal PKA activity of somatotroph adenoma cells from CNC has not been evaluated because of a limited amount of available tissue. OBJECTIVE This study examined how the PRKAR1A mutation affects the PKA signalling pathway in a human somatotrophinoma with a PRKAR1A mutation. DESIGN AND SETTING Somatotrophinoma cells from a 40-year-old male patient with CNC were used. The patient had a novel somatic heterozygous germline frameshift mutation (227delT) in PRKAR1A leading to a premature stop codon. The tumour showed loss of heterozygosity (LOH) at 17q23-24. Primary cultured adenoma cells were subjected to electrophysiological experiments to evaluate PKA signalling in individual cells. RESULTS GHRH did not increase the nonselective cation current or the voltage-gated calcium current in these adenoma cells, in contrast to nonadenomatous somatotroph cells in which these currents increase through the PKA pathway. Application of a PKA inhibitor inhibited the basal currents in these adenoma cells, results that were not observed in nonadenomatous somatotrophs. These data indicate that the basal currents are already increased and cannot be further increased by GHRH. CONCLUSIONS The results demonstrate that PKA is activated at the basal state in these adenoma cells. The data also show that both the nonselective cation current and the voltage-gated calcium current, vital regulators of GH secretion downstream of PKA, are maximally increased in these cells. These maximally increased currents probably account for the excessive GH secretion.
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Affiliation(s)
- Koji Takano
- Department of Nephrology and Endocrinology, University of Tokyo Faculty of Medicine, Hongo Bunkyo-ku, Tokyo, Japan.
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Keil MF, Stratakis CA. Advances in the Diagnosis, Treatment, and Molecular Genetics of Pituitary Adenomas in Childhood. US ENDOCRINOLOGY 2009; 4:81-85. [PMID: 19936300 PMCID: PMC2779046 DOI: 10.17925/ee.2008.04.02.81] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Margaret F Keil
- Office of the Chief, Program on Developmental Endocrinology and Genetics (PDEGEN)
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6
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Kloster MM, Hafte TT, Moltzau LR, Naderi EH, Dahle MK, Skålhegg BS, Gaudernack G, Levy FO, Naderi S, Blomhoff HK. EBV infection renders B cells resistant to growth inhibition via adenylyl cyclase. Cell Signal 2008; 20:1169-78. [PMID: 18406106 DOI: 10.1016/j.cellsig.2008.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 02/04/2008] [Accepted: 02/13/2008] [Indexed: 12/27/2022]
Abstract
Cyclic AMP (cAMP) is an important physiological growth inhibitor of lymphoid cells, and the cAMP/protein kinase A (PKA) pathway is disrupted in several immunological disorders and cancers. Epstein Barr virus (EBV) infection of B lymphocytes is responsible for the development of lymphoproliferative disease as well as certain B-lymphoid malignancies. Here we hypothesized that EBV infection might render B lymphocytes resistant to cAMP/PKA-mediated growth inhibition. To test this, we assessed the growth-inhibitory response of cAMP-elevating compounds such as forskolin and isoproterenol, as well as the PKA activator 8-CPT-cAMP in normal B lymphocytes, EBV-infected B cells and in the EBV-negative B lymphoid cell line Reh. We could demonstrate that EBV infection indeed abolished cAMP-mediated growth inhibition of B cells. The defect was pinpointed to defective adenylyl cyclase (AC) activation by forskolin and isoproterenol, resulting in reduced formation of cAMP and lack of PKA activation and CREB phosphorylation. In contrast, 8-CPT-cAMP which directly activates PKA was able to inhibit EBV-infected B cell growth. The physiological implications of these results were underlined by the observation that the ability of forskolin to inhibit camptothecin-induced apoptosis was abolished in EBV-infected B cells. We conclude that EBV infection of B cells abrogates the activation of AC and thereby cAMP formation, and that this dysfunction renders the cells resistant to growth inhibition via the cAMP/PKA pathway.
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Affiliation(s)
- Martine Müller Kloster
- Department of Biochemistry, Institute of Basic Medical Sciences, University of Oslo, N-0317 Oslo, Norway
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7
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Keil MF, Stratakis CA. Pituitary tumors in childhood: update of diagnosis, treatment and molecular genetics. Expert Rev Neurother 2008; 8:563-74. [PMID: 18416659 PMCID: PMC2743125 DOI: 10.1586/14737175.8.4.563] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Pituitary tumors are rare in childhood and adolescence, with a reported prevalence of up to one per 1 million children. Only 2-6% of surgically treated pituitary tumors occur in children. Although pituitary tumors in children are almost never malignant and hormonal secretion is rare, these tumors may result in significant morbidity. Tumors within the pituitary fossa are mainly of two types: craniopharyngiomas and adenomas. Craniopharyngiomas cause symptoms by compressing normal pituitary, causing hormonal deficiencies and producing mass effects on surrounding tissues and the brain; adenomas produce a variety of hormonal conditions such as hyperprolactinemia, Cushing disease and acromegaly or gigantism. Little is known about the genetic causes of sporadic lesions, which comprise the majority of pituitary tumors, but in children, more frequently than in adults, pituitary tumors may be a manifestation of genetic conditions such as multiple endocrine neoplasia type 1, Carney complex, familial isolated pituitary adenoma and McCune-Albright syndrome. The study of pituitary tumorigenesis in the context of these genetic syndromes has advanced our knowledge of the molecular basis of pituitary tumors and may lead to new therapeutic developments.
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Affiliation(s)
- Margaret F. Keil
- Office of the Chief, Program on Developmental Endocrinology
& Genetics (PDEGEN)
- Inter-Institute Pediatric Endocrinology Training Program,
National Institutes of Health (NIH) Bethesda, MD20892
| | - Constantine A. Stratakis
- Office of the Chief, Program on Developmental Endocrinology
& Genetics (PDEGEN)
- Section on Endocrinology & Genetics (SEGEN), PDEGEN,
National Institute of Child Health and Human Development (NICHD)
- Inter-Institute Pediatric Endocrinology Training Program,
National Institutes of Health (NIH) Bethesda, MD20892
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8
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de Sanctis L, Delmastro L, Russo MC, Matarazzo P, Lala R, de Sanctis C. Genetics of McCune-Albright syndrome. J Pediatr Endocrinol Metab 2006; 19 Suppl 2:577-82. [PMID: 16789620 DOI: 10.1515/jpem.2006.19.s2.577] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
McCune-Albright syndrome (MAS) is a rare proteiform disease due to postzygotic, somatic mutations at codon R201 of the GNAS1 gene that results in cellular mosaicism. Different methods have been used in the molecular analysis of DNA samples from several tissues of patients with one or more MAS signs, with various mutation detection rates. We review data from the literature to investigate whether patient inclusion criteria for GNAS1 analysis, the molecular methods used to search for R201 mutations, and the type of tissues analysed, can influence the mutation detection rate in MAS. Our study indicates that to overcome the problems related to GNAS1 analysis in MAS, sensitive and specific molecular methods must be used to look for the mutation from all available affected tissues and from easily accessible tissues, and even more so in the presence of atypical and monosymptomatic forms of MAS.
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Yeung CM, Chan CB, Leung PS, Cheng CHK. Cells of the anterior pituitary. Int J Biochem Cell Biol 2006; 38:1441-9. [PMID: 16621669 DOI: 10.1016/j.biocel.2006.02.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Revised: 02/18/2006] [Accepted: 02/24/2006] [Indexed: 11/29/2022]
Abstract
The anterior pituitary is made up of a number of cell types that are essential for such physiological processes as growth, development, homeostasis, metabolism, and reproduction. These include the hormonal cells corticotropes, thyrotropes, gonadotropes, somatotropes, lactotropes and a small population of mammosomatotropes, together with a non-hormonal cell type called the folliculo-stellate cells. The anterior pituitary hormonal cells are highly differentiated and are committed very early on during embryonic development. Their development is tightly regulated by both extrinsic signals as well as by endogenous gene expression. Many transcription factors that shape the development and functions of the anterior pituitary cells have been identified. Even after differentiation, pituitary cells continue to undergo mitosis and this process could be augmented under certain conditions in adulthood. Some anterior pituitary cells are multifunctional and exhibit mixed phenotypes. Pituitary tumors, which are mostly monoclonal in nature, are rather common. The molecular pathogenesis of pituitary tumorigenesis involves complex and diverse mechanisms. Aberrant intra- and extra-pituitary factors are involved. Mutations of some genes specific to pituitary tumors also play a role.
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Affiliation(s)
- Chung-Man Yeung
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
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10
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Bezerra MGT, Latronico AC, Fragoso MCBV. [Endocrine tumors associated to protein Gsalpha/Gi2alpha mutations]. ARQUIVOS BRASILEIROS DE ENDOCRINOLOGIA E METABOLOGIA 2005; 49:784-90. [PMID: 16444361 DOI: 10.1590/s0004-27302005000500019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Many oncogenic mutations promote tumor growth by inducing autonomous activity of proteins that normally transmit proliferative signal initiated by extracellular factors. G proteins are a family of guanine nucleotide binding proteins, which are structurally homologous and widely distributed in eukaryotic cells. They are composed of three different subunits (alpha, beta e gamma). The alpha subunit, which contains the guanine nucleotide-binding site, is unique to each G protein. The G proteins couple an array of seven transmembrane receptors at the cell surface with a variety of intracellular effectors, which produce second messenger molecules. A subset of endocrine tumors, such as GH- or ACTH-secreting pituitary adenomas, functioning thyroid adenomas, adrenocortical and gonadal tumors were associated with somatic activating mutations in the highly conserved codons of the Gs (Arg201 and Gln227) and Gi (Arg179 and Gln205) proteins. These findings indicated that the G proteins play a role as oncogenes, contributing with the human endocrine tumorigenesis.
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Spada A, Mantovani G, Lania A. Inactivating and activating mutations of the Gs alpha gene. ANNALES D'ENDOCRINOLOGIE 2005; 66:258-63. [PMID: 15988388 DOI: 10.1016/s0003-4266(05)81759-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- A Spada
- Institute of Endocrine Sciences, University of Milan, Ospedale Maggiore IRCCS, Via F. Sforza 35-20122 Milano Italy.
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12
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Abstract
In recent years the demonstration that human pituitary adenomas are monoclonal provides further evidence of genomic mutations occurring in the progenitor cell that subsequently undergoes clonal expansion. Up to now the only mutations identified in a significant proportion of pituitary tumors, and particular in GH-secreting adenomas, occur in the Gsalpha gene and cause constitutive activation of the cAMP pathway. Subsequent studies revealed that these mutations are associated with several feedback mechanisms that, at least in part, counteract the oncogenic potential of mutant Gsalpha. As far as the promoting agents are concerned, several lines of evidence indicate that in pituitary tumors growth factors or their receptors may be overexpressed at variable levels. The contribution of these defects in human pituitary tumorigenesis remains to be established.
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Affiliation(s)
- Anna Spada
- Institute of Endocrine Sciences, University of Milan, Ospedale Maggiore IRCCS, Via F. Sforza 35, 20122 Milan, Italy.
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13
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Vieira TCA, Cerutti JM, Dias da Silva MR, Delcelo R, Abucham J. Absence of activating mutations in the hot spots of the LH receptor and Gs-alpha genes in Leydig cell tumors. J Endocrinol Invest 2002; 25:598-602. [PMID: 12150333 DOI: 10.1007/bf03345082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Leydig-cell tumors are functioning endocrine tumors that produce T autonomously leading to isosexual precocity in boys and virilization in female patients. Molecular abnormalities such as activating mutations of the luteinizing hormone receptor (LHR), a G protein-coupled receptor, and of the Gs-alpha subunit of G protein have recently been described in these tumors. Both mutations cause continuous activation of the cAMP signaling cascade, autonomous production of T and cell proliferation. We searched for activating mutations in exon 11 of the LHR gene and in exons 8 and 9 of the Gs-a gene, which contain all hot spots for those mutations, in 4 Leydig cell tumors obtained from 4 patients (one boy with LH-independent precocious puberty and 3 women with virilization). DNA was extracted from paraffin-embedded neoplastic and non-neoplastic tissues and from peripheral lymphocytes. Hot spot regions of exons 11 of LHR and exons 8 and 9 of Gs-alpha genes were amplified by PCR and the purified PCR products were directly sequenced. No LHR or Gs-alpha gene mutations were found in the 4 tumors studied. Considering the previously reported mutations found in Leydig cell tumors, the absence of activating mutations in the hot spot regions for activating mutations in these tumors indicate molecular heterogeneity among Leydig cell tumors.
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Spada A, Beck-Peccoz P. Editorial: New strategy to solve the etiopathogenetic conundrum of pituitary adenomas. Endocrinology 2002; 143:343-6. [PMID: 11796485 DOI: 10.1210/endo.143.2.8703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Weinstein LS, Yu S, Warner DR, Liu J. Endocrine manifestations of stimulatory G protein alpha-subunit mutations and the role of genomic imprinting. Endocr Rev 2001; 22:675-705. [PMID: 11588148 DOI: 10.1210/edrv.22.5.0439] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The heterotrimeric G protein G(s) couples hormone receptors (as well as other receptors) to the effector enzyme adenylyl cyclase and is therefore required for hormone-stimulated intracellular cAMP generation. Receptors activate G(s) by promoting exchange of GTP for GDP on the G(s) alpha-subunit (G(s)alpha) while an intrinsic GTPase activity of G(s)alpha that hydrolyzes bound GTP to GDP leads to deactivation. Mutations of specific G(s)alpha residues (Arg(201) or Gln(227)) that are critical for the GTPase reaction lead to constitutive activation of G(s)-coupled signaling pathways, and such somatic mutations are found in endocrine tumors, fibrous dysplasia of bone, and the McCune-Albright syndrome. Conversely, heterozygous loss-of-function mutations may lead to Albright hereditary osteodystrophy (AHO), a disease characterized by short stature, obesity, brachydactyly, sc ossifications, and mental deficits. Similar mutations are also associated with progressive osseous heteroplasia. Interestingly, paternal transmission of GNAS1 mutations leads to the AHO phenotype alone (pseudopseudohypoparathyroidism), while maternal transmission leads to AHO plus resistance to several hormones (e.g., PTH, TSH) that activate G(s) in their target tissues (pseudohypoparathyroidism type IA). Studies in G(s)alpha knockout mice demonstrate that G(s)alpha is imprinted in a tissue-specific manner, being expressed primarily from the maternal allele in some tissues (e.g., renal proximal tubule, the major site of renal PTH action), while being biallelically expressed in most other tissues. Disrupting mutations in the maternal allele lead to loss of G(s)alpha expression in proximal tubules and therefore loss of PTH action in the kidney, while mutations in the paternal allele have little effect on G(s)alpha expression or PTH action. G(s)alpha has recently been shown to be also imprinted in human pituitary glands. The G(s)alpha gene GNAS1 (as well as its murine ortholog Gnas) has at least four alternative promoters and first exons, leading to the production of alternative gene products including G(s)alpha, XLalphas (a novel G(s)alpha isoform that is expressed only from the paternal allele), and NESP55 (a chromogranin-like protein that is expressed only from the maternal allele). A fourth alternative promoter and first exon (exon 1A) located approximately 2.5 kb upstream of the G(s)alpha promoter is normally methylated on the maternal allele and transcriptionally active on the paternal allele. In patients with isolated renal resistance to PTH (pseudohypoparathyroidism type IB), the exon 1A promoter region has a paternal-specific imprinting pattern on both alleles (unmethylated, transcriptionally active), suggesting that this region is critical for the tissue-specific imprinting of G(s)alpha. The GNAS1 imprinting defect in pseudohypoparathyroidism type IB is predicted to decrease G(s)alpha expression in renal proximal tubules. Studies in G(s)alpha knockout mice also demonstrate that this gene is critical in the regulation of lipid and glucose metabolism.
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Affiliation(s)
- L S Weinstein
- Metabolic Diseases Branch, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Seemann N, Kuhn D, Wrocklage C, Keyvani K, Hackl W, Buchfelder M, Fahlbusch R, Paulus W. CDKN2A/p16 inactivation is related to pituitary adenoma type and size. J Pathol 2001; 193:491-7. [PMID: 11276008 DOI: 10.1002/path.833] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
p16 (CDKN2A, MTS1, INK4A) status at genomic and protein levels was analysed and correlated with clinico-pathological features in 72 pituitary adenomas. Methylation of CpG islands of promoter/exon 1 sequences was found in most gonadotroph, lactotroph, plurihormonal, and null cell adenomas (36 of 44, 82%), but it was rare in somatotroph (1 of 13 cases, 8%) and corticotroph adenomas (1 of 15 cases, 7%). Homozygous CDKN2A deletion was restricted to rare somatotroph (15%) and corticotroph adenomas (13%). Immunohistochemical p16 protein expression was observed in the normal adenohypophysis, whereas it was absent in 60 of 72 (83%) tumours and reduced in another ten (14%) tumours. Staining for p16 was only seen in 5 of 15 (33%) corticotroph, 3 of 13 (23%) somatotroph, 3 of 5 (60%) plurihormonal, and 1 of 19 (5%) null cell adenomas. p16 immunonegativity without CDKN2A methylation or deletion occurred in 22 tumours, including most somatotroph and corticotroph adenomas (15 of 28, 54%). Both CDKN2A alterations and p16 negativity were related to larger tumour size. Patients with p16-negative tumours were older than patients with p16-positive tumours. These data suggest that p16 down-regulation is common in all adenoma types. The mechanisms of p16 down-regulation probably involve CDKN2A methylation in most types, but remain to be determined in somatotroph and corticotroph adenomas. These findings also suggest that p16 down-regulation is usually not an initial event, but is acquired during adenoma progression.
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Affiliation(s)
- N Seemann
- Institute of Neuropathology, University of Münster, Domagkstrasse 19, D-48129 Münster, Germany
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Hayward BE, Barlier A, Korbonits M, Grossman AB, Jacquet P, Enjalbert A, Bonthron DT. Imprinting of the G(s)alpha gene GNAS1 in the pathogenesis of acromegaly. J Clin Invest 2001; 107:R31-6. [PMID: 11254676 PMCID: PMC208949 DOI: 10.1172/jci11887] [Citation(s) in RCA: 230] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Approximately 40% of growth hormone-secreting pituitary adenomas have somatic mutations in the GNAS1 gene (the so-called gsp oncogene). These mutations at codon 201 or codon 227 constitutively activate the alpha subunit of the adenylate cyclase-stimulating G protein G(s). GNAS1 is subject to a complex pattern of genomic imprinting, its various promoters directing the production of maternally, paternally, and biallelically derived gene products. Transcripts encoding G(s)alpha are biallelically derived in most human tissues. Despite this, we show here that in 21 out of 22 gsp-positive somatotroph adenomas, the mutation had occurred on the maternal allele. To investigate the reason for this allelic bias, we also analyzed GNAS1 imprinting in the normal adult pituitary and found that G(s)alpha is monoallelically expressed from the maternal allele in this tissue. We further show that this monoallelic expression of G(s)alpha is frequently relaxed in somatotroph tumors, both in those that have gsp mutations and in those that do not. These findings imply a possible role for loss of G(s)alpha imprinting during pituitary somatotroph tumorigenesis and also suggest that G(s)alpha imprinting is regulated separately from that of the other GNAS1 products, NESP55 and XLalphas, imprinting of which is retained in these tumors.
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Affiliation(s)
- B E Hayward
- Molecular Medicine Unit, University of Leeds, St. James's University Hospital, Leeds LS9 7TF, United Kingdom
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Salvatori R, Thakker RV, Lopes MB, Fan X, Eswara JR, Ellison D, Lees P, Harding B, Yang I, Levine MA. Absence of mutations in the growth hormone (GH)-releasing hormone receptor gene in GH-secreting pituitary adenomas. Clin Endocrinol (Oxf) 2001; 54:301-7. [PMID: 11298081 DOI: 10.1046/j.1365-2265.2001.01213.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
OBJECTIVE GH-releasing hormone (GHRH) is a potent stimulator of somatotroph cell proliferation and GH secretion. GHRH acts via binding to a G-protein coupled receptor (GPCR) (GHRH-R), that activates adenylyl cyclase (AC) and increases growth and function of somatotroph cells. Indeed, a subset (30--40%) of somatotrophic adenomas contain somatic mutations of the GNAS1 gene that encodes the alpha subunit of the G-protein (G(s)alpha) that stimulates AC. As activating mutations of other GPCRs cause development of endocrine tumours, we hypothesized that somatic activating mutations of the GHRH-R might provide the molecular basis for somatotroph cell proliferation in a subset of human GH-secreting pituitary adenomas. DESIGN We analysed genomic DNA isolated from 26 somatotrophinomas, 17 of which lacked activating mutations in the GNAS1 gene. We individually amplified via polymerase chain reaction all 13 coding exons and the exon-intron boundaries of the GHRH-R gene. We used denaturing gradient gel electrophoresis to search for abnormalities in exons 1 through 11. Abnormally migrating bands were subjected to direct sequencing. Exons 12 and 13, encoding for the intracellular C-terminal domain, were subjected to direct sequencing. RESULTS Mutations were not detected in any of the tumours, but a rare polymorphism in codon 225 corresponding to the third transmembrane domain (V225I) was discovered. CONCLUSIONS GHRH-R mutations are absent or rare in somatotrophinomas, and other mechanisms must explain the somatotroph cell proliferation in the adenomas that lack activating mutations in the GNAS1 gene.
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Affiliation(s)
- R Salvatori
- Division of Endocrinology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
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Offermanns S. Mammalian G-protein function in vivo: new insights through altered gene expression. Rev Physiol Biochem Pharmacol 2000; 140:63-133. [PMID: 10857398 DOI: 10.1007/bfb0035551] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- S Offermanns
- Institut für Pharmakologie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Germany
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Watson JC, Stratakis CA, Bryant-Greenwood PK, Koch CA, Kirschner LS, Nguyen T, Carney JA, Oldfield EH. Neurosurgical implications of Carney complex. J Neurosurg 2000; 92:413-8. [PMID: 10701527 DOI: 10.3171/jns.2000.92.3.0413] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECT The authors present their neurosurgical experience with Carney complex. Carney complex, characterized by spotty skin pigmentation, cardiac myxomas, primary pigmented nodular adrenocortical disease, pituitary tumors, and nerve sheath tumors (NSTs), is a recently described, rare, autosomal-dominant familial syndrome that is relatively unknown to neurosurgeons. Neurosurgery is required to treat pituitary adenomas and a rare NST, the psammomatous melanotic schwannoma (PMS), in patients with Carney complex. Cushing's syndrome, a common component of the complex, is caused by primary pigmented nodular adrenocortical disease and is not secondary to an adrenocorticotropic hormone-secreting pituitary adenoma. METHODS The authors reviewed 14 cases of Carney complex, five from the literature and nine from their own experience. Of the 14 pituitary adenomas recognized in association with Carney complex, 12 developed growth hormone (GH) hypersecretion (producing gigantism in two patients and acromegaly in 10), and results of immunohistochemical studies in one of the other two were positive for GH. The association of PMSs with Carney complex was established in 1990. Of the reported tumors, 28% were associated with spinal nerve sheaths. The spinal tumors occurred in adults (mean age 32 years, range 18-49 years) who presented with pain and radiculopathy. These NSTs may be malignant (10%) and, as with the cardiac myxomas, are associated with significant rates of morbidity and mortality. CONCLUSIONS Because of the surgical comorbidity associated with cardiac myxoma and/or Cushing's syndrome, recognition of Carney complex has important implications for perisurgical patient management and family screening. Study of the genetics of Carney complex and of the biological abnormalities associated with the tumors may provide insight into the general pathobiological abnormalities associated with the tumors may provide insight into the general pathobiological features of pituitary adenomas and NSTs.
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Affiliation(s)
- J C Watson
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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Levine MA. Clinical implications of genetic defects in G proteins: oncogenic mutations in G alpha s as the molecular basis for the McCune-Albright syndrome. Arch Med Res 1999; 30:522-31. [PMID: 10714367 DOI: 10.1016/s0188-4409(99)00075-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Signal-transducing guanine nucleotide-binding proteins (G proteins) couple extracellular receptor proteins to intracellular effector enzymes and ion channels, and therefore are critical mediators of cellular responses to external stimuli. G proteins are comprised of three subunits (alpha, beta, gamma), each encoded by many different genes. The multiplicity of G protein subunits facilitates great combinatorial variability, which, in part, accounts for the ability of G proteins to interact with many different receptor and effector proteins. Hundreds of G protein-coupled receptors have been identified, and their unique patterns of expression among a restricted number of cell types contributes greatly to the apparent specificity of hormone action. Mutations that either activate or inactivate some of these receptors account for a number of highly specific syndromes, which affect a limited number of target tissues. By contrast, most G proteins are widely expressed in many tissues. Accordingly, mutations in these signaling molecules would be expected to produce a more generalized pattern of hormone dysfunction. Activating mutations in the gene (GNAS1) that encode the alpha subunit of the G protein that stimulates adenylyl cyclase (AC) have been identified in many endocrine neoplasms and diverse tissues of patients with McCune-Albright syndrome. The McCune-Albright syndrome is characterized by autonomous endocrine function, hyperpigmented skin lesions, and fibrous dysplasia of bone--effects which reflect the ability of CAMP to stimulate cell function and proliferation in a wide variety of tissues. The unusual features of the McCune-Albright syndrome are explained by the mosaic distribution of cells bearing the mutant allele, an observation that is most consistent with postzygotic mutation of GNAS1. Experimental analysis of this syndrome has extended our understanding of the clinical and biochemical consequences of dysfunctional G protein action and has provided a bench-to-bedside demonstration of the critical role that G proteins play in transmembrane signal transduction in humans.
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Affiliation(s)
- M A Levine
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
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