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Neto LV, Machado EDO, Luque RM, Taboada GF, Marcondes JB, Chimelli LMC, Quintella LP, Niemeyer P, de Carvalho DP, Kineman RD, Gadelha MR. Expression analysis of dopamine receptor subtypes in normal human pituitaries, nonfunctioning pituitary adenomas and somatotropinomas, and the association between dopamine and somatostatin receptors with clinical response to octreotide-LAR in acromegaly. J Clin Endocrinol Metab 2009; 94:1931-7. [PMID: 19293270 PMCID: PMC2730344 DOI: 10.1210/jc.2008-1826] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
CONTEXT Dopamine receptor (DR) and somatostatin receptor subtype expression in pituitary adenomas may predict the response to postsurgical therapies. OBJECTIVES Our objectives were to assess and compare the mRNA levels of DR1-5 and somatostatin receptors 1-5 in normal pituitaries (NPs), nonfunctioning pituitary adenomas (NFPAs), and somatotropinomas. In addition, we determined whether the level of DR expression correlates with the in vivo response to octreotide-LAR in acromegalic patients. DESIGN AND PATIENTS Eight NPs, 30 NFPAs, and 39 somatotropinomas were analyzed for receptor mRNA levels by real-time RT-PCR. The DR2 short variant was estimated as the DR2 long/DR2 total (DR2T). The relationship between DR expression and the postsurgical response to octreotide-LAR was assessed in 19 of the acromegalic patients. RESULTS DR3 was not detected. The relationship between expression levels of DR subtypes in NPs and somatotropinomas was DR2T>>>DR4>>DR5>DR1, whereas in NFPAs, DR2T>>>DR4>>DR1>DR5. The DR2 short variant was the predominant DR2 variant in the majority of samples. In acromegalics treated with octreotide-LAR, DR1 was negatively correlated with percent GH reduction (3 months: r = -0.67, P = 0.002; and 6 months: r = -0.58, P = 0.009), and DR5 was positively correlated with percent IGF-I reduction (3 months: r = 0.55, P = 0.01; and 6 months: r = 0.47, P = 0.04). CONCLUSIONS DR2 is the predominant DR subtype in NPs, NFPAs, and somatotropinomas. The fact that DR1, DR4, and DR5 are also expressed in many adenomas tested suggests that these receptors might also play a role in the therapeutic impact of postsurgical medical therapies in patients with NFPA and acromegaly. This was supported by the finding that the in vivo response to octreotide-LAR was negatively associated with DR1 and positively associated with DR5.
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Affiliation(s)
- Leonardo Vieira Neto
- Endocrinology Section, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-913, Brazil
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López León S, Croes EA, Sayed-Tabatabaei FA, Claes S, Van Broeckhoven C, van Duijn CM. The dopamine D4 receptor gene 48-base-pair-repeat polymorphism and mood disorders: a meta-analysis. Biol Psychiatry 2005; 57:999-1003. [PMID: 15860340 DOI: 10.1016/j.biopsych.2005.01.030] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2004] [Revised: 12/30/2004] [Accepted: 01/19/2005] [Indexed: 11/26/2022]
Abstract
BACKGROUND We conducted a meta-analysis to re-evaluate the role of the dopamine D4 receptor gene 48-base-pair- repeat (DRD4) polymorphism in mood disorders. METHODS DRD4 allele frequencies were compared between 917 patients with unipolar (UP) or bipolar affective disorder (BP) and 1164 control subjects from 12 samples, using the Cochrane Review Manager. RESULTS An association was found between all mood disorder groups and DRD4.2. After correcting for multiple testing, the association between DRD4.2 and BP dropped to insignificance; however, the evidence of an association between the DRD4.2 allele and UP (p < .001) and the combined group (p < .001) remained. There was no evidence for heterogeneity or publication bias. CONCLUSIONS These findings suggest that the DRD4.2 allele is a risk allele for depression symptomatology. Meta-analysis may be a valuable objective tool for a quantitative summary of evidence for association studies in psychiatric genetics.
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Affiliation(s)
- Sandra López León
- Genetic Epidemiology Unit, Department of Epidemiology and Biostatistics, Erasmus Medical Center, Rotterdam, The Netherlands
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Schoots O, Van Tol HHM. The human dopamine D4 receptor repeat sequences modulate expression. THE PHARMACOGENOMICS JOURNAL 2004; 3:343-8. [PMID: 14581929 DOI: 10.1038/sj.tpj.6500208] [Citation(s) in RCA: 171] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Genetic studies have implicated a polymorphic repeat sequence in exon 3 of the human dopamine D4 receptor in various behavioral and psychiatric disorders. Functionally various repeat variants are nearly identical, but whether these have different effects on gene expression has not been studied. To study the role of the repeat sequences on expression independently from its structural and functional effects at the protein level, we introduced these sequences immediately upstream of the promoter and in the 3' untranslated region of a luciferase reporter vector. In this report, we demonstrate that the repeat sequence can both modulate promoter activity and alter expression post-transcriptionally. The repeat sequence can serve as a substrate for a nuclear binding factor and all the three repeat variants can suppress promoter activity. Placement of the three repeat variants downstream from the luciferase gene in the expression vector shows, however, that the D4.7 repeat sequence has significantly suppressed expression of the reporter compared to the D4.2 and D4.4 repeats, likely via mechanisms involving RNA stability or translational efficiency. These data indicate that the various D4 repeat sequences have different effects on expression, which may explain its potential role in behavioral disorders.
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Affiliation(s)
- O Schoots
- Laboratory of Molecular Neurobiology, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario, Canada
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Abstract
It has recently been observed that G protein-coupled receptors (GPCRs) can interact with SH3 domains through polyproline motifs. These interactions appear to be involved in receptor internalization and MAPK signalling. Here we report that the third cytoplasmic loop of the dopamine D3 receptor can interact in vitro with the adaptor protein Grb2. While the amino- and carboxy-terminal SH3 domains of Grb2 separately did not interact with the D3 receptor loop, the interaction is at least partially maintained with a Grb2 mutant for the amino-terminal SH3 domain, but disrupted for a Grb2 mutant with a nonfunctional carboxy-terminal SH3 domain. The data indicate the need of structural integrity of the entire Grb2 protein for the interaction and dominant role of the carboxy-terminal SH3 domain in the interaction. Disruption of the PXXP motifs in the D3 receptor did not affect the interaction with Grb2. These results indicate that GPCRs may contain SH3 ligands that do not contain the postulated minimal consensus sequence PXXP.
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Affiliation(s)
- J Oldenhof
- Laboratory of Molecular Neurobiology, Centre for Addiction and Mental Health, M5T 1R8, Toronto, ON, Canada
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Freeman ME, Kanyicska B, Lerant A, Nagy G. Prolactin: structure, function, and regulation of secretion. Physiol Rev 2000; 80:1523-631. [PMID: 11015620 DOI: 10.1152/physrev.2000.80.4.1523] [Citation(s) in RCA: 1463] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Prolactin is a protein hormone of the anterior pituitary gland that was originally named for its ability to promote lactation in response to the suckling stimulus of hungry young mammals. We now know that prolactin is not as simple as originally described. Indeed, chemically, prolactin appears in a multiplicity of posttranslational forms ranging from size variants to chemical modifications such as phosphorylation or glycosylation. It is not only synthesized in the pituitary gland, as originally described, but also within the central nervous system, the immune system, the uterus and its associated tissues of conception, and even the mammary gland itself. Moreover, its biological actions are not limited solely to reproduction because it has been shown to control a variety of behaviors and even play a role in homeostasis. Prolactin-releasing stimuli not only include the nursing stimulus, but light, audition, olfaction, and stress can serve a stimulatory role. Finally, although it is well known that dopamine of hypothalamic origin provides inhibitory control over the secretion of prolactin, other factors within the brain, pituitary gland, and peripheral organs have been shown to inhibit or stimulate prolactin secretion as well. It is the purpose of this review to provide a comprehensive survey of our current understanding of prolactin's function and its regulation and to expose some of the controversies still existing.
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Affiliation(s)
- M E Freeman
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4340, USA.
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Kapsimali M, Vidal B, Gonzalez A, Dufour S, Vernier P. Distribution of the mRNA encoding the four dopamine D1 receptor subtypes in the brain of the european eel (Anguilla anguilla): Comparative approach to the function of D1 receptors in vertebrates. J Comp Neurol 2000. [DOI: 10.1002/(sici)1096-9861(20000410)419:3%3c320::aid-cne5%3e3.0.co;2-f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kapsimali M, Vidal B, Gonzalez A, Dufour S, Vernier P. Distribution of the mRNA encoding the four dopamine D(1) receptor subtypes in the brain of the european eel (Anguilla anguilla): comparative approach to the function of D(1) receptors in vertebrates. J Comp Neurol 2000; 419:320-43. [PMID: 10723008 DOI: 10.1002/(sici)1096-9861(20000410)419:3<320::aid-cne5>3.0.co;2-f] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Four subtypes of D(1) dopamine receptors are expressed in the brain of the European eel (Anguilla anguilla), an elopomorph teleost. To correlate this molecular multiplicity with specific localisation and functions, the distribution of the D(1) receptor transcripts was analysed by in situ hybridisation. The four D(1) receptor transcripts exhibit largely overlapping expression territories. In telencephalon, they are found in the olfactory bulb and the dorsal telencephalon (except its lateral part) but are most abundant in the subpallial areas. More caudally, the entopeduncular nucleus, preoptic nuclei, preglomerular nuclear complex, ventral thalamus, periventricular hypothalamus, optic tectum and cerebellum, all contain various amounts of D(1) receptor transcripts. Finally, D(1) receptor mRNAs are present in nuclei associated with the cranial nerves. The two D(1A) receptor subtypes are generally the most abundant and present a different distribution in several areas. The D(1B) mRNA, although present in fewer areas than D(1A) transcripts, is the most abundant in ventrolateral telencephalon and torus semicircularis. The D(1C) receptor transcript, which has not been found in mammals, is restricted to diencephalon and cerebellum. In view of the expression territories of D(1) receptor transcripts and previous data, some areas of the everted telencephalon of teleost may be homologous to regions of the tetrapod brain. In particular, D(1) expression territories of the ventral telencephalon are likely to be equivalent to striatal areas. These observations suggest an evolutionary scenario in which the D(1A) receptor subtype was highly conserved after the first gene duplication during the evolution of craniates, whereas D(1B) and D(1C), and their associated specific characteristics, appeared later, probably in the gnathostome lineage.
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Affiliation(s)
- M Kapsimali
- Institut Alfred Fessard, UPR2212, CNRS, 91198 Gif-sur-Yvette Cedex, France
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Nguyen B, Carbajal ME, Vitale ML. Intracellular mechanisms involved in dopamine-induced actin cytoskeleton organization and maintenance of a round phenotype in cultured rat lactotrope cells. Endocrinology 1999; 140:3467-77. [PMID: 10433202 DOI: 10.1210/endo.140.8.6905] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The participation of the actin cytoskeleton in the control of PRL secretion by dopamine (DA) is not yet fully understood. Recently, we demonstrated that DA induces cortical actin assembly and stabilization in anterior pituitary PRL-secreting cells (lactotropes) that can be linked to DA-induced inhibition of PRL secretion. Here we show that DA prevents cell flattening and the formation of cytoplasmic actin cables in cultured rat lactotropes. The effects of DA were reversible, mediated by D2 receptors, exclusive to lactotropes, and independent of other anterior pituitary cells present in the cultures. Because cAMP and Ca2+ mediate DA-induced inhibition of PRL secretion and synthesis, we investigated whether morphological responses to DA were dependent on these second messengers. Either inhibition of protein kinase A activity with the specific inhibitor KT5720 or blockade of Ca2+ channels with nifedipine inhibited cell flattening and induced cytoplasmic actin filament breakdown. Nifedipine was as effective as DA, but KT5720 was less effective than DA. Increased intracellular cAMP levels provoked cell flattening, which was blocked by nifedipine and KT5720, but not by DA. The results suggest that Ca2+-dependent pathways control cell shape in most lactotropes; however, in a subpopulation of lactotropes, cAMP-dependent pathways may also contribute to DA morphological responses. Next, we studied the participation of the Rho family of guanosine triphosphatases, which is known to regulate the dynamics of actin filaments. Inactivation of Rho by C3 exoenzyme induced cytoplasmic actin cable disassembly and lactotrope rounding up. No additive effects were observed among Rho-, cAMP-, and Ca2+-dependent pathways. However, C3-induced morphological responses were blocked by increased cAMP levels, suggesting that Rho-dependent steps are upstream cAMP-dependent steps. DA-induced actin cytoskeleton reorganization in lactotropes may involve modifications in the expression and localization of actin-binding proteins. DA increased expression of the actin anchoring proteins talin and alpha-actinin, but not of vinculin. DA enhanced association of talin to cell membranes. Increased talin-membrane interaction may be implicated in DA-induced maintenance of a round phenotype in lactotrope cells.
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Affiliation(s)
- B Nguyen
- Department of Pathology and Cell Biology, Faculty of Medicine, University of Montréal, Québec, Canada
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Abstract
Prolactin is one of two major hormones involved in lactation. While the role of infant suckling and oxytocin in the lactation process are well understood, the role of prolactin is less clear. A variety of factors related to prolactin have been investigated, and these are used as an organizing framework for this article. Factors include pregnancy, lactation, nursing frequency, prior lactation experience, milk production, and pharmacologic agents. The literature, while substantial in amount, presents inconsistencies. Implications for practice are discussed.
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Affiliation(s)
- P D Hill
- University of Illinois at Chicago, College of Nursing, USA
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Diamond SE, Chiono M, Gutierrez-Hartmann A. Reconstitution of the protein kinase A response of the rat prolactin promoter: differential effects of distinct Pit-1 isoforms and functional interaction with Oct-1. Mol Endocrinol 1999; 13:228-38. [PMID: 9973253 DOI: 10.1210/mend.13.2.0227] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
PRL gene transcription is primarily regulated by dopamine, which lowers cAMP levels and inhibits protein kinase A (PKA) activity. Current data indicate that the cAMP/PKA response maps to the most proximal Pit-1/Pit-1beta binding site footprint I (FP I) on the rat PRL (rPRL) promoter. Pit-1, a POU-homeo domain transcription factor, is specifically expressed in the anterior pituitary and is required both for the normal development of anterior pituitary cell types, somatotrophs, lactotrophs, and thyrotrophs, and for the expression of their hormones: GH, PRL, and TSHbeta. Pit-1 has been shown to functionally interact, via FP I, with several transcription factors, including Oct-1, a ubiquitous homeobox protein, and thyrotroph embryonic factor, which is found in lactotrophs, to activate basal rPRL promoter activity. Pit-1beta/GHF-2, a distinct splice isoform of Pit-1, acts to inhibit Ras-activated transcription from the rPRL promoter, which is mediated by a functional interaction between Pit-1 and Ets-1 at the most distal Pit-1 binding site (FP IV). In this manuscript we show 1) that the Pit-1beta isoform not only fails to block PKA activation, but is, in fact, a superior mediator of the PKA response; 2) that the PKA response requires intact POU-specific and POU-homeo domains of Pit-1; and 3) that Oct-1, but not thyrotroph embryonic factor, functions as a Pit-1-interacting factor to mediate an optimal PKA response.
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Affiliation(s)
- S E Diamond
- Department of Medicine, Colorado Cancer Center, University of Colorado Health Sciences Center, Denver 80262, USA
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Knapp M, Wong AH, Schoots O, Guan HC, Van Tol HH. Promoter-independent regulation of cell-specific dopamine receptor expression. FEBS Lett 1998; 434:108-14. [PMID: 9738461 DOI: 10.1016/s0014-5793(98)00961-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Here we describe the construction of recombinant adenoviruses expressing dopamine D2 and D4 receptors, and their ability to mediate high levels of heterologous expression in a variety of cell types in vitro and in vivo for at least 7 days post infection. These experiments demonstrated that maximum receptor expression is achieved generally within 24 h and remains constant thereafter. Maximum expression levels were highly variable between cell lines and dependent on infection efficiency and promoter strength. Correction for these two variables revealed differences in relative expression levels between cell lines varying by two orders of magnitude. Our results indicate that in addition to gene transcription, post-transcriptional mechanisms play a dominant role in determining dopamine receptor levels in this system.
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Affiliation(s)
- M Knapp
- Laboratory of Molecular Neurobiology, Clarke Institute of Psychiatry, University of Toronto, Ont., Canada
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