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Rudajev V, Novotny J. The Role of Lipid Environment in Ganglioside GM1-Induced Amyloid β Aggregation. MEMBRANES 2020; 10:membranes10090226. [PMID: 32916822 PMCID: PMC7558528 DOI: 10.3390/membranes10090226] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 01/14/2023]
Abstract
Ganglioside GM1 is the most common brain ganglioside enriched in plasma membrane regions known as lipid rafts or membrane microdomains. GM1 participates in many modulatory and communication functions associated with the development, differentiation, and protection of neuronal tissue. It has, however, been demonstrated that GM1 plays a negative role in the pathophysiology of Alzheimer's disease (AD). The two features of AD are the formation of intracellular neurofibrillary bodies and the accumulation of extracellular amyloid β (Aβ). Aβ is a peptide characterized by intrinsic conformational flexibility. Depending on its partners, Aβ can adopt different spatial arrangements. GM1 has been shown to induce specific changes in the spatial organization of Aβ, which lead to enhanced peptide accumulation and deleterious effect especially on neuronal membranes containing clusters of this ganglioside. Changes in GM1 levels and distribution during the development of AD may contribute to the aggravation of the disease.
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Ujcikova H, Cechova K, Jagr M, Roubalova L, Vosahlikova M, Svoboda P. Proteomic analysis of protein composition of rat hippocampus exposed to morphine for 10 days; comparison with animals after 20 days of morphine withdrawal. PLoS One 2020; 15:e0231721. [PMID: 32294144 PMCID: PMC7159219 DOI: 10.1371/journal.pone.0231721] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 03/30/2020] [Indexed: 01/08/2023] Open
Abstract
Opioid addiction is recognized as a chronic relapsing brain disease resulting from repeated exposure to opioid drugs. Cellular and molecular mechanisms underlying the ability of organism to return back to the physiological norm after cessation of drug supply are not fully understood. The aim of this work was to extend our previous studies of morphine-induced alteration of rat forebrain cortex protein composition to the hippocampus. Rats were exposed to morphine for 10 days and sacrificed 24 h (groups +M10 and −M10) or 20 days after the last dose of morphine (groups +M10/−M20 and −M10/−M20). The six altered proteins (≥2-fold) were identified in group (+M10) when compared with group (−M10) by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE). The number of differentially expressed proteins was increased to thirteen after 20 days of the drug withdrawal. Noticeably, the altered level of α-synuclein, β-synuclein, α-enolase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was also determined in both (±M10) and (±M10/−M20) samples of hippocampus. Immunoblot analysis of 2D gels by specific antibodies oriented against α/β-synucleins and GAPDH confirmed the data obtained by 2D-DIGE analysis. Label-free quantification identified nineteen differentially expressed proteins in group (+M10) when compared with group (−M10). After 20 days of morphine withdrawal (±M10/−M20), the number of altered proteins was increased to twenty. We conclude that the morphine-induced alteration of protein composition in rat hippocampus after cessation of drug supply proceeds in a different manner when compared with the forebrain cortex. In forebrain cortex, the total number of altered proteins was decreased after 20 days without morphine, whilst in hippocampus, it was increased.
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Affiliation(s)
- Hana Ujcikova
- Laboratory of Membrane Receptors, Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
- * E-mail:
| | - Kristina Cechova
- Laboratory of Membrane Receptors, Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University in Prague, Prague 2, Czech Republic
| | - Michal Jagr
- Laboratory of Analysis of Biologically Important Compounds, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Lenka Roubalova
- Laboratory of Membrane Receptors, Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Miroslava Vosahlikova
- Laboratory of Membrane Receptors, Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
| | - Petr Svoboda
- Laboratory of Membrane Receptors, Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague 4, Czech Republic
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Roubalova L, Vosahlikova M, Brejchova J, Sykora J, Rudajev V, Svoboda P. High Efficacy but Low Potency of δ-Opioid Receptor-G Protein Coupling in Brij-58-Treated, Low-Density Plasma Membrane Fragments. PLoS One 2015; 10:e0135664. [PMID: 26285205 PMCID: PMC4540457 DOI: 10.1371/journal.pone.0135664] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 07/25/2015] [Indexed: 11/18/2022] Open
Abstract
Principal Findings HEK293 cells stably expressing PTX-insensitive δ-opioid receptor-Gi1α (C351I) fusion protein were homogenized, treated with low concentrations of non-ionic detergent Brij-58 at 0°C and fractionated by flotation in sucrose density gradient. In optimum range of detergent concentrations (0.025–0.05% w/v), Brij-58-treated, low-density membranes exhibited 2-3-fold higher efficacy of DADLE-stimulated, high-affinity [32P]GTPase and [35S]GTPγS binding than membranes of the same density prepared in the absence of detergent. The potency of agonist DADLE response was significantly decreased. At high detergent concentrations (>0.1%), the functional coupling between δ-opioid receptors and G proteins was completely diminished. The same detergent effects were measured in plasma membranes isolated from PTX-treated cells. Therefore, the effect of Brij-58 on δ-opioid receptor-G protein coupling was not restricted to the covalently bound Gi1α within δ-opioid receptor-Gi1α fusion protein, but it was also valid for PTX-sensitive G proteins of Gi/Go family endogenously expressed in HEK293 cells. Characterization of the direct effect of Brij-58 on the hydrophobic interior of isolated plasma membranes by steady-state anisotropy of diphenylhexatriene (DPH) fluorescence indicated a marked increase of membrane fluidity. The time-resolved analysis of decay of DPH fluorescence by the “wobble in cone” model of DPH motion in the membrane indicated that the exposure to the increasing concentrations of Brij-58 led to a decreased order and higher motional freedom of the dye. Summary Limited perturbation of plasma membrane integrity by low concentrations of non-ionic detergent Brij-58 results in alteration of δ-OR-G protein coupling. Maximum G protein-response to agonist stimulation (efficacy) is increased; affinity of response (potency) is decreased. The total degradation plasma membrane structure at high detergent concentrations results in diminution of functional coupling between δ-opioid receptors and G proteins.
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Affiliation(s)
- Lenka Roubalova
- Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Miroslava Vosahlikova
- Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jana Brejchova
- Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jan Sykora
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czech Republic
| | - Vladimir Rudajev
- Department of Neurochemistry, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Petr Svoboda
- Department of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
- * E-mail:
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Brejchová J, Sýkora J, Ostašov P, Merta L, Roubalová L, Janáček J, Hof M, Svoboda P. TRH-receptor mobility and function in intact and cholesterol-depleted plasma membrane of HEK293 cells stably expressing TRH-R-eGFP. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:781-96. [DOI: 10.1016/j.bbamem.2014.11.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 11/24/2014] [Accepted: 11/26/2014] [Indexed: 01/03/2023]
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Ujcikova H, Eckhardt A, Kagan D, Roubalova L, Svoboda P. Proteomic analysis of post-nuclear supernatant fraction and percoll-purified membranes prepared from brain cortex of rats exposed to increasing doses of morphine. Proteome Sci 2014; 12:11. [PMID: 24528483 PMCID: PMC3936806 DOI: 10.1186/1477-5956-12-11] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 02/03/2014] [Indexed: 11/10/2022] Open
Abstract
Background Proteomic analysis was performed in post-nuclear supernatant (PNS) and Percoll-purified membranes (PM) prepared from fore brain cortex of rats exposed to increasing doses of morphine (10–50 mg/kg) for 10 days. Results In PNS, the 10 up (↑)- or down (↓)-regulated proteins exhibiting the largest morphine-induced change were selected, excised manually from the gel and identified by MALDI-TOF MS/MS: 1-(gi|148747414, Guanine deaminase), ↑2.5×; 2-(gi|17105370, Vacuolar-type proton ATP subunit B, brain isoform), ↑2.6×; 3-(gi|1352384, Protein disulfide-isomerase A3), ↑3.4×; 4-(gi|40254595, Dihydropyrimidinase-related protein 2), ↑3.6×; 5-(gi|149054470, N-ethylmaleimide sensitive fusion protein, isoform CRAa), ↑2.0×; 6-(gi|42476181, Malate dehydrogenase, mitochondrial precursor), ↑1.4×; 7-(gi|62653546, Glyceraldehyde-3-phosphate dehydrogenase), ↑1.6×; 8-(gi|202837, Aldolase A), ↑1.3×; 9-(gi|31542401, Creatine kinase B-type), ↓0.86×; 10-(gi|40538860, Aconitate hydratase, mitochondrial precursor), ↑1.3×. The identified proteins were of cytoplasmic (1, 4, 5, 7, 9), cell membrane (2), endoplasmic reticulum (3) and mitochondrial (6, 8, 10) origin and 9 of them were significantly increased, 1.3-3.6×. The 4 out of 9 up-regulated proteins (4, 6, 7, 10) were described as functionally related to oxidative stress; the 2 proteins participate in genesis of apoptotic cell death. In PM, the 18 up (↑)- or down (↓)-regulated proteins were identified by LC-MS/MS and were of plasma membrane [Brain acid soluble protein, ↓2.1×; trimeric Gβ subunit, ↓2.0x], myelin membrane [MBP, ↓2.5×], cytoplasmic [Internexin, ↑5.2×; DPYL2, ↑4.9×; Ubiquitin hydrolase, ↓2.0×; 60S ribosomal protein, ↑2.7×; KCRB, ↓2.6×; Sirtuin-2, ↑2.5×; Peroxiredoxin-2, ↑2.2×; Septin-11, ↑2.2×; TERA, ↑2.1×; SYUA, ↑2.0×; Coronin-1A, ↓5.4×] and mitochondrial [Glutamate dehydrogenase 1, ↑2.7×; SCOT1, ↑2.2×; Prohibitin, ↑2.2×; Aspartate aminotransferase, ↓2.2×] origin. Surprisingly, the immunoblot analysis of the same PM resolved by 2D-ELFO indicated that the “active”, morphine-induced pool of Gβ subunits represented just a minor fraction of the total signal of Gβ which was decreased 1.2x only. The dominant signal of Gβ was unchanged. Conclusion Brain cortex of rats exposed to increasing doses of morphine is far from being adapted. Significant up-regulation of proteins functionally related to oxidative stress and apoptosis suggests a major change of energy metabolism resulting in the state of severe brain cell “discomfort” or even death.
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Affiliation(s)
| | | | | | | | - Petr Svoboda
- Laboratories of Biochemistry of Membrane Receptors, Institute of Physiology, v,v,i,, Academy of Sciences of the Czech Republic, Videnska 1083, Prague 4 14220, Czech Republic.
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Ujcikova H, Dlouha K, Roubalova L, Vosahlikova M, Kagan D, Svoboda P. Up-regulation of adenylylcyclases I and II induced by long-term adaptation of rats to morphine fades away 20days after morphine withdrawal. Biochim Biophys Acta Gen Subj 2011; 1810:1220-9. [DOI: 10.1016/j.bbagen.2011.09.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 09/12/2011] [Accepted: 09/27/2011] [Indexed: 02/04/2023]
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Ostasov P, Krusek J, Durchankova D, Svoboda P, Novotny J. Ca2+ responses to thyrotropin-releasing hormone and angiotensin II: the role of plasma membrane integrity and effect of G11alpha protein overexpression on homologous and heterologous desensitization. Cell Biochem Funct 2008; 26:264-74. [PMID: 18041110 DOI: 10.1002/cbf.1453] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The molecular mechanisms involved in GPCR-initiated signaling cascades where the two receptors share the same signaling cascade, such as thyrotropin-releasing hormone (TRH) and angiotensin II (ANG II), are still far from being understood. Here, we analyzed hormone-induced Ca(2+) responses and the process of desensitization in HEK-293 cells, which express endogenous ANG II receptors. These cells were transfected to express exogenously high levels of TRH receptors (clone E2) or both TRH receptors and G(11)alpha protein (clone E2M11). We observed that the characteristics of the Ca(2+) response, as well as the process of desensitization, were both strongly dependent on receptor number and G(11)alpha protein level. Whereas treatment of E2 cells with TRH or ANG II led to significant desensitization of the Ca(2+) response to subsequent addition of either hormone, the response was not desensitized in E2M11 cells expressing high levels of G(11)alpha. In addition, stimulation of both cell lines with THR elicited a clear heterologous desensitization to subsequent stimulation with ANG II. On the other hand, ANG II did not affect a subsequent response to TRH. ANG II-mediated signal transduction was strongly dependent on plasma membrane integrity modified by cholesterol depletion, but signaling through TRH receptors was altered only slightly under these conditions. It may be concluded that the level of expression of G-protein-coupled receptors and their cognate G-proteins strongly influences not only the magnitude of the Ca(2+) response but also the process of desensitization and resistance to subsequent hormone addition.
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Affiliation(s)
- Pavel Ostasov
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Sadler SE, Archer MR, Spellman KM. Activation of the progesterone-signaling pathway by methyl-beta-cyclodextrin or steroid in Xenopus laevis oocytes involves release of 45-kDa Galphas. Dev Biol 2008; 322:199-207. [PMID: 18706402 DOI: 10.1016/j.ydbio.2008.07.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 07/01/2008] [Accepted: 07/23/2008] [Indexed: 11/26/2022]
Abstract
Treatment of Xenopus laevis oocytes with cholesterol-depleting methyl-beta-cyclodextrin (MebetaCD) stimulates phosphorylation of mitogen-activated protein kinase (MAPK) and oocyte maturation, as reported previously [Sadler, S.E., Jacobs, N.D., 2004. Stimulation of Xenopus laevis oocyte maturation by methyl-beta-cyclodextrin. Biol. Reprod. 70, 1685-1692.]. Here we report that treatment of oocytes with MebetaCD increased levels of immunodetectable 39-kDa mos protein. The protein synthesis inhibitor, cycloheximide, blocked the appearance of Mos, blocked MebetaCD-stimulated phosphorylation of MAPK, and inhibited MebetaCD-induced oocyte maturation. These observations suggest that MebetaCD activates the progesterone-signaling pathway. Chemical inhibition of steroid synthesis and mechanical removal of follicle cells were used to verify that MebetaCD acts at the level of the oocyte and does not require production of steroid by surrounding follicle cells. Cortical Galpha(s) is contained in low-density membrane; and treatment of oocytes with progesterone or MebetaCD reduced immunodetectable levels of Galpha(s) protein in cortices and increased internal levels of 45-kDa Galpha(s) in cortical-free extracts. Dose-dependent increases in internal Galpha(s) after treatment of oocytes with progesterone correlated with the steroid-induced maturation response, and the increase in internal Galpha(s) after hormone treatment was comparable to the decrease in cortical Galpha(s). These results are consistent with a model in which release of Galpha(s) from the plasma membrane is involved in activation of the progesterone-signaling pathway that leads to amphibian oocyte maturation.
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Affiliation(s)
- Susan E Sadler
- Department of Biological Sciences, University of Denver, Denver, Colorado 80208, USA.
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9
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Schermuly RT, Pullamsetti SS, Breitenbach SC, Weissmann N, Ghofrani HA, Grimminger F, Nilius SM, Schrör K, Meger-Kirchrath J, Seeger W, Rose F. Iloprost-induced desensitization of the prostacyclin receptor in isolated rabbit lungs. Respir Res 2007; 8:4. [PMID: 17257398 PMCID: PMC1802745 DOI: 10.1186/1465-9921-8-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Accepted: 01/26/2007] [Indexed: 01/08/2023] Open
Abstract
Background The rapid desensitization of the human prostacyclin (IP) in response to agonist binding has been shown in cell culture. Phosphorylation of the IP receptor by protein kinase C (PKC) has been suggested to be involved in this process. Methods and results In this study we investigated the vasodilatory effects of iloprost, a stable prostacyclin analogue, in perfused rabbit lungs. Continuous infusion of the thromboxane mimetic U46619 was employed to establish stable pulmonary hypertension. A complete loss of the vasodilatory response to iloprost was observed in experiments with continuous iloprost perfusion, maintaining the intravascular concentration of this prostanoid over a 180 min period. When lungs under chronic iloprost infusion were acutely challenged with inhaled iloprost, a corresponding complete loss of vasoreactivity was observed. This desensitization was not dependent on upregulation of cAMP-specific phosphodiesterases or changes in adenylate cyclase activity, as suggested by unaltered dose-response curves to agents directly affecting these enzymes. Application of a prostaglandin E1 receptor antagonist 6-isopropoxy-9-oxoxanthene-2-carboxylic acid (AH 6809) or the PKC inhibitor bisindolylmaleimide I (BIM) enhanced the vasodilatory response to infused iloprost and partially prevented tachyphylaxis. Conclusion A three-hour infusion of iloprost in pulmonary hypertensive rabbit lungs results in complete loss of the lung vasodilatory response to this prostanoid. This rapid desensitization is apparently not linked to changes in adenylate cyclase and phosphodiesterase activation, but may involve PKC function and co-stimulation of the EP1 receptor in addition to the IP receptor by this prostacyclin analogue.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
- Administration, Inhalation
- Animals
- Cell Culture Techniques
- Colforsin/pharmacology
- Cyclic AMP/metabolism
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Drug Tolerance
- Female
- Hypertension, Pulmonary/chemically induced
- Hypertension, Pulmonary/drug therapy
- Iloprost/pharmacology
- Infusions, Parenteral
- Lung/cytology
- Lung/drug effects
- Male
- Myocytes, Smooth Muscle/metabolism
- Rabbits
- Receptors, Epoprostenol/drug effects
- Vasodilator Agents/pharmacology
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Affiliation(s)
- Ralph T Schermuly
- University of Giessen Lung Center (UGLC), Medical Clinic II/V, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Soni S Pullamsetti
- University of Giessen Lung Center (UGLC), Medical Clinic II/V, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Susanne C Breitenbach
- University of Giessen Lung Center (UGLC), Medical Clinic II/V, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Norbert Weissmann
- University of Giessen Lung Center (UGLC), Medical Clinic II/V, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Hossein A Ghofrani
- University of Giessen Lung Center (UGLC), Medical Clinic II/V, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Friedrich Grimminger
- University of Giessen Lung Center (UGLC), Medical Clinic II/V, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Sigrid M Nilius
- Institut fuer Pharmakologie und Klinische Pharmakologie, Heinrich-Heine-Universitaet Duesseldorf, 40225 Duesseldorf, Germany
| | - Karsten Schrör
- Institut fuer Pharmakologie und Klinische Pharmakologie, Heinrich-Heine-Universitaet Duesseldorf, 40225 Duesseldorf, Germany
| | - Jutta Meger-Kirchrath
- Institut fuer Pharmakologie und Klinische Pharmakologie, Heinrich-Heine-Universitaet Duesseldorf, 40225 Duesseldorf, Germany
| | - Werner Seeger
- University of Giessen Lung Center (UGLC), Medical Clinic II/V, Justus-Liebig-University Giessen, 35392 Giessen, Germany
| | - Frank Rose
- University of Giessen Lung Center (UGLC), Medical Clinic II/V, Justus-Liebig-University Giessen, 35392 Giessen, Germany
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Mehlmann LM. Stops and starts in mammalian oocytes: recent advances in understanding the regulation of meiotic arrest and oocyte maturation. Reproduction 2006; 130:791-9. [PMID: 16322539 DOI: 10.1530/rep.1.00793] [Citation(s) in RCA: 318] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mammalian oocytes grow and undergo meiosis within ovarian follicles. Oocytes are arrested at the first meiotic prophase, held in meiotic arrest by the surrounding follicle cells until a surge of LH from the pituitary stimulates the immature oocyte to resume meiosis. Meiotic arrest depends on a high level of cAMP within the oocyte. This cAMP is generated by the oocyte, through the stimulation of the G(s) G-protein by the G-protein-coupled receptor, GPR3. Stimulation of meiotic maturation by LH occurs via its action on the surrounding somatic cells rather than on the oocyte itself. LH induces the expression of epidermal growth factor-like proteins in the mural granulosa cells that act on the cumulus cells to trigger oocyte maturation. The signaling pathway between the cumulus cells and the oocyte, however, remains unknown. This review focuses on recent studies highlighting the importance of the oocyte in producing cAMP to maintain arrest, and discusses possible targets at the level of the oocyte on which LH could act to stimulate meiotic resumption.
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Affiliation(s)
- Lisa M Mehlmann
- Department of Cell Biology, University of Connecticut Health Center, 263 Farmington Ave., Farmington, Connecticut 06032, USA.
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11
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Freudzon L, Norris RP, Hand AR, Tanaka S, Saeki Y, Jones TLZ, Rasenick MM, Berlot CH, Mehlmann LM, Jaffe LA. Regulation of meiotic prophase arrest in mouse oocytes by GPR3, a constitutive activator of the Gs G protein. ACTA ACUST UNITED AC 2006; 171:255-65. [PMID: 16247026 PMCID: PMC2171177 DOI: 10.1083/jcb.200506194] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The arrest of meiotic prophase in mouse oocytes within antral follicles requires the G protein G(s) and an orphan member of the G protein-coupled receptor family, GPR3. To determine whether GPR3 activates G(s), the localization of Galpha(s) in follicle-enclosed oocytes from Gpr3(+/+) and Gpr3(-/-) mice was compared by using immunofluorescence and Galpha(s)GFP. GPR3 decreased the ratio of Galpha(s) in the oocyte plasma membrane versus the cytoplasm and also decreased the amount of Galpha(s) in the oocyte. Both of these properties indicate that GPR3 activates G(s). The follicle cells around the oocyte are also necessary to keep the oocyte in prophase, suggesting that they might activate GPR3. However, GPR3-dependent G(s) activity was similar in follicle-enclosed and follicle-free oocytes. Thus, the maintenance of prophase arrest depends on the constitutive activity of GPR3 in the oocyte, and the follicle cell signal acts by a means other than increasing GPR3 activity.
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Affiliation(s)
- Leon Freudzon
- Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06032
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Rudajev V, Novotny J, Hejnova L, Milligan G, Svoboda P. Dominant Portion of Thyrotropin-Releasing Hormone Receptor Is Excluded from Lipid Domains. Detergent-Resistant and Detergent-Sensitive Pools of TRH Receptor and Gqα/G11α Protein. ACTA ACUST UNITED AC 2005; 138:111-25. [PMID: 16091585 DOI: 10.1093/jb/mvi114] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Some G protein-coupled receptors might be spacially targetted to discrete domains within the plasma membrane. Here we assessed the localization in membrane domains of the epitope-tagged, fluorescent version of thyrotropin-releasing hormone receptor (VSV-TRH-R-GFP) expressed in HEK293 cells. Our comparison of three different methods of cell fractionation (detergent extraction, alkaline treatment/sonication and mechanical homogenization) indicated that the dominant portion of plasma membrane pool of the receptor was totally solubilized by Triton X-100 and its distribution was similar to that of transmembrane plasma membrane proteins (glycosylated and non-glycosylated forms of CD147, MHCI, CD29, CD44, transmembrane form of CD58, Tapa1 and Na,K-ATPase). As expected, caveolin and GPI-bound proteins CD55, CD59 and GPI-bound form of CD58 were preferentially localized in detergent-resistant membrane domains (DRMs). Trimeric G proteins G(q)alpha/G(11)alpha, G(i)alpha1/G(i)alpha2, G(s)alphaL/G(s)alphaS and Gbeta were distributed almost equally between detergent-resistant and detergent-solubilized pools. In contrast, VSV-TRH-R-GFP, Galpha, Gbeta and caveolin were localized massively only in low-density membrane fragments of plasma membranes, which were generated by alkaline treatment/sonication or by mechanical homogenization of cells. These data indicate that VSV-TRH-R-GFP as well as other transmembrane markers of plasma membranes are excluded from TX-100-resistant, caveolin-enriched membrane domains. Trimeric G protein G(q)alpha/G(11)alpha occurs in both DRMs and in the bulk of plasma membranes, which is totally solubilized by TX-100.
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Affiliation(s)
- Vladimir Rudajev
- Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
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Matousek P, Durchánková D, Svandová I, Novotny J, Svoboda P. Agonist-induced tyrosine phosphorylation of Gq/G11α requires the intact structure of membrane domains. Biochem Biophys Res Commun 2005; 328:526-32. [PMID: 15694379 DOI: 10.1016/j.bbrc.2005.01.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Indexed: 01/12/2023]
Abstract
Stimulation of receptors coupled to G(q)/G(11) protein may induce phosphorylation on a tyrosine residue of the alpha subunit of this G protein, which is an essential event for G(q)/G(11) activation. Here we observed that in HEK293 cells stably expressing high levels of thyrotropin-releasing hormone (TRH) receptors and G(11)alpha protein the maximal tyrosine phosphorylation of G(q)/G(11)alpha was reached within 10 min of TRH stimulation and then it faded away at longer time periods of agonist exposure. The G(q)/G(11)alpha protein levels did not change during this treatment. Incubation of intact cells with beta-cyclodextrin (beta CD) for 40 min prior to hormone exposure significantly decreased the rapid transient tyrosine phosphorylation. Subsequent replenishment of cholesterol levels reversed the former negative effect of beta CD. Isolation of caveolin-enriched, detergent-resistant membrane domains indicated destruction of these structures in beta CD-treated cells. These data indicate that the preserved integrity of plasma membrane domains/caveolae is required for complete agonist-induced phosphorylation of G(q)/G(11)alpha.
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Affiliation(s)
- Petr Matousek
- Institute of Physiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic
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