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Moritz AE, Madaras NS, Rankin ML, Inbody LR, Sibley DR. Delineation of G Protein-Coupled Receptor Kinase Phosphorylation Sites within the D 1 Dopamine Receptor and Their Roles in Modulating β-Arrestin Binding and Activation. Int J Mol Sci 2023; 24:6599. [PMID: 37047571 PMCID: PMC10095280 DOI: 10.3390/ijms24076599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 03/27/2023] [Accepted: 03/29/2023] [Indexed: 04/05/2023] Open
Abstract
The D1 dopamine receptor (D1R) is a G protein-coupled receptor that signals through activating adenylyl cyclase and raising intracellular cAMP levels. When activated, the D1R also recruits the scaffolding protein β-arrestin, which promotes receptor desensitization and internalization, as well as additional downstream signaling pathways. These processes are triggered through receptor phosphorylation by G protein-coupled receptor kinases (GRKs), although the precise phosphorylation sites and their role in recruiting β-arrestin to the D1R remains incompletely described. In this study, we have used detailed mutational and in situ phosphorylation analyses to completely identify the GRK-mediated phosphorylation sites on the D1R. Our results indicate that GRKs can phosphorylate 14 serine and threonine residues within the C-terminus and the third intracellular loop (ICL3) of the receptor, and that this occurs in a hierarchical fashion, where phosphorylation of the C-terminus precedes that of the ICL3. Using β-arrestin recruitment assays, we identified a cluster of phosphorylation sites in the proximal region of the C-terminus that drive β-arrestin binding to the D1R. We further provide evidence that phosphorylation sites in the ICL3 are responsible for β-arrestin activation, leading to receptor internalization. Our results suggest that distinct D1R GRK phosphorylation sites are involved in β-arrestin binding and activation.
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Affiliation(s)
| | | | | | | | - David R. Sibley
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, USA
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Guo S, Bai Y, Zhang Q, Zhang H, Fan Y, Han H, Liu Y. Associations of CALM1 and DRD1 polymorphisms, and their expression levels, with Taihang chicken egg-production traits. Anim Biotechnol 2021:1-11. [PMID: 34890302 DOI: 10.1080/10495398.2021.2008948] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Egg production by hens is an important reproductive performance index in the poultry industry. To investigate the effects of the CALM1 and DRD1 genes on egg production in chicken, their mRNA expression and single nucleotide polymorphisms (SNP) levels were investigated, and bioinformatics and egg-production association analyses were performed. Three SNPs (g.44069941G > A and g.44069889A > G in CALM1 and g.10742639C > T in DRD1) were detected in the exons and introns of CALM1 and DRD1 in 400 Taihang chickens. Among them, g.44069941G > A was significantly associated with Taihang chicken egg production on the 500th day (p < 0.05), whereas g.10742639C > T was significantly associated with the 300th day (p < 0.05). The expression levels of CALM1 and DRD1 in ovarian tissues of a high-yielding Taihang group were greater than in a low-yielding group (p < 0.05). The bioinformatics analysis revealed that the mutations influenced the mRNA secondary structures of CALM1 and DRD1. This study provides new insights into the potential effects of CALM1 and DRD1 polymorphisms on chicken egg production. The two SNPs g.44069941G > A and g.10742639C > T are potential molecular markers for improving the reproductive traits of Taihang chicken.
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Affiliation(s)
- Siwu Guo
- College of Life Sciences and Food Engineering, Hebei University of Engineering, Handan, China
| | - Ying Bai
- College of Life Sciences and Food Engineering, Hebei University of Engineering, Handan, China
| | - Qingyang Zhang
- College of Life Sciences and Food Engineering, Hebei University of Engineering, Handan, China
| | - Hui Zhang
- College of Life Sciences and Food Engineering, Hebei University of Engineering, Handan, China
| | - Yekai Fan
- College of Life Sciences and Food Engineering, Hebei University of Engineering, Handan, China
| | - Haiyin Han
- College of Life Sciences and Food Engineering, Hebei University of Engineering, Handan, China
| | - Yufang Liu
- College of Life Sciences and Food Engineering, Hebei University of Engineering, Handan, China
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Zhang B, Albaker A, Plouffe B, Lefebvre C, Tiberi M. Constitutive activities and inverse agonism in dopamine receptors. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 70:175-214. [PMID: 24931197 DOI: 10.1016/b978-0-12-417197-8.00007-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The concept of activation in the absence of agonists has been demonstrated for many GPCRs and is now solidified as one of the principal aspects of GPCR signaling. In this chapter, we review how dopamine receptors demonstrate this ability. Although difficult to prove in vivo due to the presence of endogenous dopamine and lack of subtype-selective inverse agonists and "pure" antagonists (neutral ligands), in vitro assays such as measuring intracellular cAMP, [(35)S]GTPγS binding, and [(3)H]thymidine incorporation have uncovered the constitutive activation of D1- and D2-class receptors. Nevertheless, because of limited and inconsistent findings, the existence of constitutive activity for D2-class receptors is currently not well established. Mutagenesis studies have shown that basal signaling, notably by D1-class receptors, is governed by the collective contributions of transmembrane domains and extracellular/intracellular loops, such as the third extracellular loop, the third intracellular loop, and C-terminal tail. Furthermore, constitutive activities of D1-class receptors are subjected to regulation by kinases. Among the dopamine receptor family, the D5 receptor subtype exhibits a higher basal signaling and bears resemblance to constitutively active mutant forms of GPCRs. The presence of its constitutive activity in vivo and its pathophysiological relevance, with a brief mention of other subtypes, are also discussed.
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Affiliation(s)
- Boyang Zhang
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
| | - Awatif Albaker
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
| | - Bianca Plouffe
- Department of Biochemistry, Université de Montréal, Montréal, Québec, Canada; Institut de recherche en immunologie, cancer, Montréal, Québec, Canada
| | - Caroline Lefebvre
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
| | - Mario Tiberi
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada.
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Inhibiting subthalamic D5 receptor constitutive activity alleviates abnormal electrical activity and reverses motor impairment in a rat model of Parkinson's disease. J Neurosci 2013; 33:14840-9. [PMID: 24027284 DOI: 10.1523/jneurosci.0453-13.2013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Burst firing has been reported as a pathological activity of subthalamic nucleus (STN) neurons in Parkinson's disease. However, the origin of bursts and their causal link with motor deficits remain unknown. Here we tested the hypothesis that dopamine D5 receptors (D5Rs), characterized by a high constitutive activity, may contribute to the emergence of burst firing in STN. We tested whether inhibiting D5R constitutive activity depresses burst firing and alleviates motor impairments in the 6-OHDA rat model of Parkinson's disease. Intrasubthalamic microinjections of either an inverse agonist of D5Rs, flupenthixol, or a D2R antagonist, raclopride, were applied. Behavioral experiments, in vivo and in vitro electrophysiological recordings, and ex vivo functional neuroanatomy studies were performed. Using [(5)S]GTPγ binding autoradiography, we show that application of flupenthixol inhibits D5R constitutive activity within the STN. Furthermore, flupenthixol reduced evoked burst in brain slices and converted pathological burst firing into physiological tonic, single-spike firing in 6-OHDA rats in vivo. This later action was mimicked by calciseptine, a Cav1 channel blocker. Moreover, the same treatment dramatically attenuated motor impairment in this model and normalized metabolic hyperactivity in both STN and substantia nigra pars reticulata, the main output structure of basal ganglia in rats. In contrast, raclopride as well as saline did not reverse burst firing and motor deficits, confirming the selective action of flupenthixol on D5Rs. These results are the first to demonstrate that subthalamic D5Rs are involved in the pathophysiology of Parkinson's disease and that administering an inverse agonist of these receptors may lessen motor symptoms.
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Functional analysis of human D1 and D5 dopaminergic G protein-coupled receptors: lessons from mutagenesis of a conserved serine residue in the cytosolic end of transmembrane region 6. Methods Mol Biol 2013; 964:141-80. [PMID: 23296783 DOI: 10.1007/978-1-62703-251-3_10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In mammals, dopamine G protein-coupled receptors (GPCR) are segregated into two categories: D1-like (D1R and D5R) and D2-like (D2R(short), D2R(long), D3R, and D4R) subtypes. D1R and D5R are primarily coupled to stimulatory heterotrimeric GTP-binding proteins (Gs/olf) leading to activation of adenylyl cyclase and production of intracellular cAMP. D1R and D5R share high level of amino acid identity in transmembrane (TM) regions. Yet these two GPCR subtypes display distinct ligand binding and G protein coupling properties. In fact, our studies suggest that functional properties reported for constitutively active mutants of GPCRs (e.g., increased basal activity, higher agonist affinity and intrinsic activity) are also observed in cells expressing wild type D5R when compared with wild type D1R. Herein, we describe an experimental method based on mutagenesis and transfection of human embryonic kidney 293 (HEK293) cells to explore the molecular mechanisms regulating ligand affinity, agonist-independent and dependent activity of D1R and D5R. We will demonstrate how to mutate one conserved residue in the cytosolic end of TM6 of D1R (Ser263) and D5R (Ser287) by modifying two or three nucleotides in the cDNA of human D1-like receptors. Genetically modified D1R and D5R cDNAs are prepared using a polymerase chain reaction method, propagated in E. coli, purified and mutations confirmed by DNA sequencing. Receptor expression constructs are transfected into HEK293 cells cultured in vitro at 37°C in 5% CO(2) environment and used in radioligand binding and whole cAMP assays. In this study, we will test the effect of S263A/G/D and S287A/G/D mutations on ligand binding and DA-dependent activation of D1R and D5R.
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Plouffe B, Yang X, Tiberi M. The third intracellular loop of D1 and D5 dopaminergic receptors dictates their subtype-specific PKC-induced sensitization and desensitization in a receptor conformation-dependent manner. Cell Signal 2011; 24:106-18. [PMID: 21893192 DOI: 10.1016/j.cellsig.2011.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 08/05/2011] [Accepted: 08/17/2011] [Indexed: 01/11/2023]
Abstract
We previously showed that phorbol-12-myristate-13-acetate (PMA) mediates a robust PKC-dependent sensitization and desensitization of the highly homologous human Gs protein and adenylyl cyclase (AC)-linked D1 (hD1R) and D5 (hD5R) dopaminergic receptors, respectively. Here, we demonstrate using forskolin-mediated AC stimulation that PMA-mediated hD1R sensitization and hD5R desensitization is not associated with changes in AC activity. We next employed a series of chimeric hD1R and hD5R to delineate the underlying structural determinants dictating the subtype-specific regulation of human D1-like receptors by PMA. We first used chimeric receptors in which the whole terminal region (TR) spanning from the extracellular face of transmembrane domain 6 to the end of cytoplasmic tail (CT) or CT alone were exchanged between hD1R and hD5R. CT and TR swaps lead to chimeric hD1R and hD5R retaining PMA-induced sensitization and desensitization of wild type parent receptors. In striking contrast, hD1R sensitization and hD5R desensitization mediated by PMA are correspondingly switched to PMA-induced receptor desensitization and sensitization following the IL3 swap between hD1R and hD5R. Cell treatment with the PKC blocker, Gö6983, inhibits PMA-induced regulation of these chimeric receptors in a similar fashion to wild type receptors. Further studies with chimeras constructed by exchanging IL3 and TR show that PMA-induced regulation of these chimeras remains fully switched relative to their respective wild type parent receptor. Interestingly, results obtained with the exchange of IL3 and TR also reveal that the D1-like subtype-specific regulation by PMA, while fully dictated by IL3, can be modulated in a receptor conformation-dependent manner. Overall, our results strongly suggest that IL3 is the critical determinant underlying the subtype-specific regulation of human D1-like receptor responsiveness by PKC.
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Affiliation(s)
- Bianca Plouffe
- Ottawa Hospital Research Institute, Department of Medicine, University of Ottawa, Ottawa, ON, Canada
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Wanjerkhede SM, Bapi RS. Role of CAMKII in reinforcement learning: a computational model of glutamate and dopamine signaling pathways. BIOLOGICAL CYBERNETICS 2011; 104:397-424. [PMID: 21701878 DOI: 10.1007/s00422-011-0439-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2011] [Accepted: 05/30/2011] [Indexed: 05/31/2023]
Abstract
Timely release of dopamine (DA) at the striatum seems to be important for reinforcement learning (RL) mediated by the basal ganglia. Houk et al. (in: Houk et al (eds) Models of information processing in the basal ganglia, (1995) proposed a cellular signaling pathway model to characterize the interaction between DA and glutamate pathways that have a role in RL. The model simulation results, using GENESIS KINETIKIT simulator, point out that there is not only prolongation of duration as proposed by Houk et al. (1995), but also an enhancement in the amplitude of autophosphorylation of CaMKII. Further, the autophosphorylated form of CaMKII may form a basis for the "eligibility trace" condition required in RL. This simulation study is the first of its kind to support the comprehensive theoretical proposal of Houk et al. (1995).
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Affiliation(s)
- Shesharao M Wanjerkhede
- Department of Computer Science, Guru Nanak Dev Engineering College, Bidar, Karanataka, India.
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Steele SL, Yang X, Debiais-Thibaud M, Schwerte T, Pelster B, Ekker M, Tiberi M, Perry SF. In vivo and in vitro assessment of cardiac beta-adrenergic receptors in larval zebrafish (Danio rerio). J Exp Biol 2011; 214:1445-57. [PMID: 21490253 DOI: 10.1242/jeb.052803] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
β-Adrenergic receptors (βARs) are crucial for maintaining the rate and force of cardiac muscle contraction in vertebrates. Zebrafish (Danio rerio) have one β1AR gene and two β2AR genes (β2aAR and β2bAR). We examined the roles of these receptors in larval zebrafish in vivo by assessing the impact of translational gene knockdown on cardiac function. Zebrafish larvae lacking β1AR expression by morpholino knockdown displayed lower heart rates than control fish, whereas larvae deficient in both β2aAR and β2bAR expression exhibited significantly higher heart rates than controls. These results suggested a potential inhibitory role for one or both β2AR genes. By using cultured HEK293 cells transfected with zebrafish βARs, we demonstrated that stimulation with adrenaline or procaterol (a β2AR agonist) resulted in an increase in intracellular cAMP levels in cells expressing any of the three zebrafish βARs. In comparison with its human βAR counterpart, zebrafish β2aAR expressed in HEK293 cells appeared to exhibit a unique binding affinity profile for adrenergic ligands. Specifically, zebrafish β2aAR had a high binding affinity for phenylephrine, a classical α-adrenergic receptor agonist. The zebrafish receptors also had distinct ligand binding affinities for adrenergic agonists when compared with human βARs in culture, with zebrafish β2aAR being distinct from human β2AR and zebrafish β2bAR. Overall, this study provides insight into the function and evolution of both fish and mammalian β-adrenergic receptors.
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Affiliation(s)
- Shelby L Steele
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5.
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Xu H, Shen X, Zhou M, Fang M, Zeng H, Nie Q, Zhang X. The genetic effects of the dopamine D1 receptor gene on chicken egg production and broodiness traits. BMC Genet 2010; 11:17. [PMID: 20199684 PMCID: PMC2848132 DOI: 10.1186/1471-2156-11-17] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 03/03/2010] [Indexed: 11/10/2022] Open
Abstract
Background The elevation of egg production and the inhibition of incubation behavior are the aims of modern poultry production. Prolactin (PRL) gene is confirmed to be critical for the onset and maintenance of these reproductive behaviors in birds. Through PRL, dopamine D1 receptor (DRD1) was also involved in the regulation of chicken reproductive behavior. However, the genetic effects of this gene on chicken egg production and broodiness have not been studied extensively. The objective of this research was to evaluate the genetic effects of the DRD1 gene on chicken egg production and broodiness traits. Results In this study, the chicken DRD1 gene was screened for the polymorphisms by cloning and sequencing and 29 variations were identified in 3,342 bp length of this gene. Seven single nucleotide polymorphism (SNPs) among these variations, including a non-synonymous mutation (A+505G, Ser169Gly), were located in the coding region and were chosen to analyze their association with chicken egg production and broodiness traits in 644 Ningdu Sanhuang individuals. Two SNPs, G+123A and C+1107T, were significantly associated with chicken broody frequency (P < 0.05). Significant association was also found between the G+1065A - C+1107T haplotypes and chicken broody frequency (P < 0.05). In addition, the haplotypes of G+123A and T+198C were significantly associated with weight of first egg (EW) (P = 0.03). On the other hand, the distribution of the DRD1 mRNA was observed and the expression difference was compared between broodiness and non-broodiness chickens. The DRD1 mRNA was predominantly expressed in subcutaneous fat and abdominal fat of non-broodiness chicken, and then in heart, kidney, oviduct, glandular stomach, hypothalamus, and pituitary. In subcutaneous fat and abdominal fat, the level of non-broodiness was 26 to 28 times higher than that of broodiness. In pituitary, it was 5-fold higher. In heart, oviduct, and kidney, a 2-3 times decrease from non-broodiness to broodiness was displayed. In glandular stomach and hypothalamus, the level seen in non-broodiness and broodiness was almost the same. Conclusion The polymorphisms of the DRD1 gene and their haplotypes were associated with chicken broody frequency and some egg production traits. The mRNA distribution was significant different between broodiness and non-broodiness chickens.
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Affiliation(s)
- Haiping Xu
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou 510642, Guangdong, China.
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D'Aoust JP, Tiberi M. Role of the extracellular amino terminus and first membrane-spanning helix of dopamine D1 and D5 receptors in shaping ligand selectivity and efficacy. Cell Signal 2010; 22:106-16. [DOI: 10.1016/j.cellsig.2009.09.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Accepted: 09/14/2009] [Indexed: 01/28/2023]
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Plouffe B, D'Aoust JP, Laquerre V, Liang B, Tiberi M. Probing the constitutive activity among dopamine D1 and D5 receptors and their mutants. Methods Enzymol 2010; 484:295-328. [PMID: 21036239 DOI: 10.1016/b978-0-12-381298-8.00016-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Dopamine D1 and D5 receptors are prototypical cell-surface seven-transmembrane (TM) G protein-coupled receptors (GPCRs) mediating elevation of intracellular cAMP levels. The high level of constitutive activity of D5 receptor mediating intracellular cAMP production is one of the functional hallmarks distinguishing the closely related D1-like dopaminergic subtypes (D1 and D5). D1-like subtypes share over 80% identity within their TM regions. Thus, D1 and D5 receptors can serve as unparalleled and useful molecular tools to gain structural and mechanistic insights into subtype-specific determinants regulating GPCR constitutive activation and inverse agonism. A method has been developed that relies on the use of transfected human embryonic kidney 293 cells with wild-type (WT), epitope-tagged, chimeric, truncated, and mutant forms of mammalian D1 and D5 receptors using a modified DNA and calcium phosphate precipitation procedure. Receptor expression levels are quantified by a radioligand binding using [(3)H]-SCH23390, a D1-like selective drug. Regulation of ligand-independent and dependent activity of WT and mutated D1 and D5 receptors is determined by whole cell cAMP assays using metabolic [(3)H]-adenine labeling and sequential purification radiolabeled nucleotides over Dowex and alumina resin columns. Results on the regulation of D1 and D5 constitutive activity are presented here. Our studies indicate that dopamine-mediated D5 receptor stimulation in a dose-dependent manner is not always detectable, suggesting that D5 receptors can exist in a "locked" constitutively activated state. This "locked" constitutively active state of D5 receptor is not linked to aberrant high receptor expression levels or cell behavior, as D1 receptor function remains essentially unchanged in these cells. In fact, we show that phorbol ester treatment of cells harboring "locked" constitutively active D5 receptors abrogates constitutive activation of D5R to allow its stimulation by dopamine in a dose-dependent manner.
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Affiliation(s)
- Bianca Plouffe
- Ottawa Hospital Research Institute (Neurosciences), Department of Medicine, University of Ottawa, Ontario, Canada
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12
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Zhou C, Tiberi M, Liang B, Alper SL, Baltz JM. HCO3(-)/Cl(-) exchange inactivation and reactivation during mouse oocyte meiosis correlates with MEK/MAPK-regulated Ae2 plasma membrane localization. PLoS One 2009; 4:e7417. [PMID: 19823673 PMCID: PMC2757902 DOI: 10.1371/journal.pone.0007417] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 09/16/2009] [Indexed: 11/18/2022] Open
Abstract
Background Germinal Vesicle (GV) stage mouse oocytes in first meiotic prophase exhibit highly active HCO3−/Cl− exchange—a class of transport nearly ubiquitously involved in regulation of intracellular pH and cell volume. During meiosis, however, oocyte HCO3−/Cl− exchange becomes inactivated during first metaphase (MI), remains inactive in second metaphase (MII), and is reactivated only after egg activation. Previous work using pharmacological manipulations had indicated that activity of the MEK/MAPK signaling pathway was negatively correlated with HCO3−/Cl− exchange activity during meiosis. However, the mechanism by which the exchanger is inactivated during meiotic progression had not been determined, nor had the role of MEK/MAPK been directly established. Methodology/Principal Findings Expression of a constitutively active form of MEK (MAP kinase kinase), which prevented the normal downregulation of MAPK after egg activation, also prevented reactivation of HCO3−/Cl− exchange. Conversely, suppression of endogenous MAPK activity with dominant negative MEK activated the normally quiescent HCO3−/Cl− exchange in mature MII eggs. A GFP-tagged form of the HCO3−/Cl− exchanger isoform Ae2 (Slc4a2) was strongly expressed at the GV oocyte plasma membrane, but membrane localization decreased markedly during meiotic progression. A similar pattern for endogenous Ae2 was confirmed by immunocytochemistry. The loss of membrane-localized Ae2 appeared selective, since membrane localization of a GFP-tagged human dopamine D1 receptor did not change during meiotic maturation. Conclusions Direct manipulation of MAPK activity indicated that GFP-tagged Ae2 localization depended upon MAPK activity. Inactivation of HCO3−/Cl− exchange during the meiotic cell cycle may therefore reflect the loss of Ae2 from the oocyte plasma membrane, downstream of MEK/MAPK signaling. This identifies a novel role for MEK/MAPK-mediated cytostatic factor (CSF) activity during meiosis in membrane protein trafficking in mouse oocytes, and shows for the first time that selective retrieval of membrane proteins is a feature of meiosis in mammalian oocytes.
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Affiliation(s)
- Chenxi Zhou
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Division of Reproductive Medicine, Department of Obstetrics and Gynecology, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
| | - Mario Tiberi
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
- Departments of Psychiatry and Medicine, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
| | - Binhui Liang
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
- Departments of Psychiatry and Medicine, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
| | - Seth L. Alper
- Molecular and Vascular Medicine Unit and Renal Division, Beth Israel Deaconess Medical Center, and Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jay M. Baltz
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Division of Reproductive Medicine, Department of Obstetrics and Gynecology, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa Faculty of Medicine, Ottawa, Ontario, Canada
- * E-mail:
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Jackson A, Sedaghat K, Minerds K, James C, Tiberi M. Opposing effects of phorbol-12-myristate-13-acetate, an activator of protein kinase C, on the signaling of structurally related human dopamine D1 and D5 receptors. J Neurochem 2006; 95:1387-400. [PMID: 16313517 DOI: 10.1111/j.1471-4159.2005.03476.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The 'cross-talk' between different types of neurotransmitters through second messenger pathways represents a major regulatory mechanism in neuronal function. We investigated the effects of activation of protein kinase C (PKC) on cAMP-dependent signaling by structurally related human D1-like dopaminergic receptors. Human embryonic kidney 293 (HEK293) cells expressing D1 or D5 receptors were pretreated with phorbol-12-myristate-13-acetate (PMA), a potent activator of PKC, followed by analysis of dopamine-mediated receptor activation using whole cell cAMP assays. Unpredictably, PKC activation had completely opposite effects on D1 and D5 receptor signaling. PMA dramatically augmented agonist-evoked D1 receptor signaling, whereas constitutive and dopamine-mediated D5 receptor activation were rapidly blunted. RT-PCR and immunoblotting analyses showed that phorbol ester-regulated PKC isozymes (conventional: alpha, betaI, betaII, gamma; novel: delta, epsilon, eta, theta) and protein kinase D (PKCmicro) are expressed in HEK293 cells. PMA appears to mediate these contrasting effects through the activation of Ca2+-independent novel PKC isoforms as revealed by specific inhibitors, bisindolylmaleimide I, Gö6976, and Gö6983. The finding that cross-talk between PKC and cAMP pathways can produce such opposite outcomes following the activation of structurally similar D1-like receptor subtypes is novel and further strengthens the view that D1 and D5 receptors serve distinct functions in the mammalian nervous and endocrine systems.
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Affiliation(s)
- Adele Jackson
- Ottawa Health Research Institute, Ottawa Hospital (Civic Campus), and Department of Medicine/Cellular and Molecular Medicine/Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
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Venugopalan VV, Ghali Z, Sénécal J, Reader TA, Descarries L. Catecholaminergic activation of G-protein coupling in rat spinal cord: further evidence for the existence of dopamine and noradrenaline receptors in spinal grey and white matter. Brain Res 2006; 1070:90-100. [PMID: 16423330 DOI: 10.1016/j.brainres.2005.10.101] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Revised: 10/26/2005] [Accepted: 10/31/2005] [Indexed: 11/26/2022]
Abstract
[35S]GTPgammaS autoradiography of slide-mounted tissue sections was used to examine G-protein coupling in the rat spinal cord, as stimulated by dopamine, the D1 receptor agonist SKF 38393, noradrenaline, and noradrenaline in the presence of the alpha adrenoceptor antagonist, phentolamine. Measurements were obtained from the different laminae of spinal grey and from the dorsal, lateral, and ventral columns of white matter, at cervical, thoracic, and lumbar levels. At every level, there was a relatively strong basal incorporation of GTPgammaS in laminae II-III>lamina IV-X of spinal grey, even in presence of DPCPX to block endogenous activation by adenosine A1 receptors. Dopamine, and to a lesser degree SKF 38393, but not the D2 receptor agonist quinpirole, stimulated G-protein coupling in laminae IV-X. Both dopamine and SKF 38393 also induced a weak but significant activation throughout the white matter. In both grey and white matter, the activation by dopamine was markedly reduced in presence of a selective D1 receptor antagonist. Noradrenaline strongly stimulated coupling throughout the spinal grey at all levels, an effect that was uniformly reduced in the presence of phentolamine. With or without phentolamine, there was also significant stimulation by noradrenaline in the white matter. Under the same experimental conditions, alpha 1, alpha 2, and beta adrenergic receptor agonists failed to activate GTPgammaS incorporation in either grey or white matter. However, in the presence of selective alpha 1 or alpha 2 receptor antagonist, significant reductions of noradrenaline-stimulated GTPgammaS incorporation were observed in both grey and white matter. The beta antagonist propanolol reduced GTPgammaS incorporation in grey matter only. Thus, the results confirmed the existence of D1 dopamine receptors and of alpha 1, alpha 2, and beta adrenergic receptors in the grey matter of rat spinal cord. In white matter, they strongly suggested the presence of dopamine D1, and of alpha 1 and alpha 2 adrenergic receptors on glia and/or microvessels, that might be activated by diffuse transmission in vivo.
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Affiliation(s)
- V V Venugopalan
- Département de Physiologie, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada H3C 3J7
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15
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Baufreton J, Zhu ZT, Garret M, Bioulac B, Johnson SW, Taupignon AI. Dopamine receptors set the pattern of activity generated in subthalamic neurons. FASEB J 2005; 19:1771-7. [PMID: 16260646 DOI: 10.1096/fj.04-3401hyp] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Information processing in the brain requires adequate background neuronal activity. As Parkinson's disease progresses, patients typically become akinetic; the death of dopaminergic neurons leads to a dopamine-depleted state, which disrupts information processing related to movement in a brain area called the basal ganglia. Using agonists of dopamine receptors in the D1 and D2 families on rat brain slices, we show that dopamine receptors in these two families govern the firing pattern of neurons in the subthalamic nucleus, a crucial part of the basal ganglia. We propose a conceptual frame, based on specific properties of dopamine receptors, to account for the dominance of different background firing patterns in normal and dopamine-depleted states.
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Affiliation(s)
- J Baufreton
- UMR 5543, University Victor Segalen, Bordeaux, France
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16
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Tumova K, Zhang D, Tiberi M. Role of the fourth intracellular loop of D1-like dopaminergic receptors in conferring subtype-specific signaling properties. FEBS Lett 2004; 576:461-7. [PMID: 15498581 DOI: 10.1016/j.febslet.2004.09.059] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2004] [Revised: 09/17/2004] [Accepted: 09/20/2004] [Indexed: 11/30/2022]
Abstract
We investigate whether the fourth intracellular loop (IL4) of D1 and D5 dopaminergic receptors (D1R, D5R) confers D1-like subtype-specific signaling properties. Using chimeric receptors (D1R-IL4B and D5R-IL4A), we show that swapping of IL4 leads to a switch in dopamine affinity and constitutive activity of D1R and D5R. Dopamine potency was reduced for both chimeras in comparison with wild-type receptors. Moreover, dopamine-mediated maximal activation was drastically increased in cells expressing D1R-IL4B when compared with those harboring D5R-IL4A or wild-type receptors. In conclusion, IL4 plays a pivotal role in imparting subtype-specific ligand binding and activation properties to highly homologous seven-transmembrane receptors.
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Affiliation(s)
- Katerina Tumova
- Ottawa Health Research Institute, Neuroscience Program, and Departments of Medicine/Cellular and Molecular Medicine/Psychiatry, University of Ottawa, Ottawa, ON, Canada
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17
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Milligan G. Constitutive activity and inverse agonists of G protein-coupled receptors: a current perspective. Mol Pharmacol 2004; 64:1271-6. [PMID: 14645655 DOI: 10.1124/mol.64.6.1271] [Citation(s) in RCA: 213] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Over the last decade, the ability to detect agonist-independent signal transduction by G protein-coupled receptors has in turn resulted in the detection and study of ligands able to block this activity. Such ligands are generically described as inverse agonists. Considerable attention has recently been devoted to the presence and roles of endogenous antagonist/inverse agonists and the concept that inverse agonists may have specific therapeutic benefits compared with neutral antagonists.
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Affiliation(s)
- Graeme Milligan
- Davidson Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
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Kim OJ, Gardner BR, Williams DB, Marinec PS, Cabrera DM, Peters JD, Mak CC, Kim KM, Sibley DR. The role of phosphorylation in D1 dopamine receptor desensitization: evidence for a novel mechanism of arrestin association. J Biol Chem 2003; 279:7999-8010. [PMID: 14660631 PMCID: PMC4743542 DOI: 10.1074/jbc.m308281200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Homologous desensitization of D(1) dopamine receptors is thought to occur through their phosphorylation leading to arrestin association which interdicts G protein coupling. In order to identify the relevant domains of receptor phosphorylation, and to determine how this leads to arrestin association, we created a series of mutated D(1) receptor constructs. In one mutant, all of the serine/threonine residues within the 3rd cytoplasmic domain were altered (3rdTOT). A second construct was created in which only three of these serines (serines 256, 258, and 259) were mutated (3rd234). We also created four truncation mutants of the carboxyl terminus (T347, T369, T394, and T404). All of these constructs were comparable with the wild-type receptor with respect to expression and adenylyl cyclase activation. In contrast, both of the 3rd loop mutants exhibited attenuated agonist-induced receptor phosphorylation that was correlated with an impaired desensitization response. Sequential truncation of the carboxyl terminus of the receptor resulted in a sequential loss of agonist-induced phosphorylation. No phosphorylation was observed with the most severely truncated T347 mutant. Surprisingly, all of the truncated receptors exhibited normal desensitization. The ability of the receptor constructs to promote arrestin association was evaluated using arrestin-green fluorescent protein translocation assays and confocal fluorescence microscopy. The 3rd234 mutant receptor was impaired in its ability to induce arrrestin translocation, whereas the T347 mutant was comparable with wild type. Our data suggest a model in which arrestin directly associates with the activated 3rd cytoplasmic domain in an agonist-dependent fashion; however, under basal conditions, this is sterically prevented by the carboxyl terminus of the receptor. Receptor activation promotes the sequential phosphorylation of residues, first within the carboxyl terminus and then the 3rd cytoplasmic loop, thereby dissociating these domains and allowing arrestin to bind to the activated 3rd loop. Thus, the role of receptor phosphorylation is to allow access of arrestin to its receptor binding domain rather than to create an arrestin binding site per se.
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Affiliation(s)
- Ok-Jin Kim
- Molecular Neuropharmacology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892-1406
| | - Benjamin R. Gardner
- Molecular Neuropharmacology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892-1406
| | - Daniel B. Williams
- Molecular Neuropharmacology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892-1406
| | - Paul S. Marinec
- Molecular Neuropharmacology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892-1406
| | - David M. Cabrera
- Molecular Neuropharmacology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892-1406
| | - Jennifer D. Peters
- Molecular Neuropharmacology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892-1406
| | - Chun C. Mak
- Molecular Neuropharmacology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892-1406
| | - Kyeong-Man Kim
- College of Pharmacy, Chonnam National University, KwangJu, 500-757, Korea
| | - David R. Sibley
- Molecular Neuropharmacology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892-1406
- To whom correspondence should be addressed: Molecular Neuropharmacology Section, NINDS/National Institutes of Health, Bldg. 10, Rm. 5C108, 10 Center Dr., MSC 1406, Bethesda, MD 20892-1406. Tel.: 301-496-9316; Fax: 301-496-6609;
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