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Liu J, Zhang C. Xenopus cell-free extracts and their applications in cell biology study. BIOPHYSICS REPORTS 2023; 9:195-205. [PMID: 38516620 PMCID: PMC10951473 DOI: 10.52601/bpr.2023.230016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 12/05/2023] [Indexed: 03/23/2024] Open
Abstract
Xenopus has proven to be a remarkably versatile model organism in the realm of biological research for numerous years, owing to its straightforward maintenance in laboratory settings and its abundant provision of ample-sized oocytes, eggs, and embryos. The cell cycle of these oocytes, eggs, and early embryos exhibits synchrony, and extracts derived from these cells serve various research purposes. Many fundamental concepts in biochemistry, cell biology, and development have been elucidated through the use of cell-free extracts derived from Xenopus cells. Over the past few decades, a wide array of cell-free extracts has been prepared from oocytes, eggs, and early embryos of different Xenopus species at varying cell cycle stages. Each of these extracts possesses distinct characteristics. This review provides a concise overview of the Xenopus species employed in laboratory research, the diverse types of cell-free extracts available, and their respective properties. Furthermore, this review delves into the extensive investigation of spindle assembly in Xenopus egg extracts, underscoring the versatility and potency of these cell-free systems in the realm of cell biology.
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Affiliation(s)
- Junjun Liu
- Department of Biological Sciences, California State Polytechnic University, Pomona, CA 91768, USA
| | - Chuanmao Zhang
- The Academy for Cell and Life Health, Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming 650500, China
- The Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing 100871, China
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2
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O'Shea LC, Fair T, Hensey C. X-linked α-thalassemia with mental retardation is downstream of protein kinase A in the meiotic cell cycle signaling cascade in Xenopus oocytes and is dynamically regulated in response to DNA damage†. Biol Reprod 2020; 100:1238-1249. [PMID: 30649195 DOI: 10.1093/biolre/ioz001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 10/19/2018] [Accepted: 01/08/2019] [Indexed: 12/19/2022] Open
Abstract
X-linked α-thalassemia with mental retardation (ATRX) is a chromatin remodeling protein that belongs to the SWItch/sucrose non-fermentable (SWI2/SNF2) family of helicase/ATPases. During meiosis, ATRX is necessary for heterochromatin formation and maintenance of chromosome stability in order to ensure proper assembly of the metaphase II spindle. Previously, we established ATRX as a novel progesterone regulated protein during bovine meiotic maturation, in addition to being dynamically regulated in response to DNA damage in oocytes. In the present study, we utilize the Xenopus laevis model system to further elucidate the signaling pathways regulating ATRX expression within the oocyte. Here, we present an analysis of endogenous ATRX protein expression during oogenesis, oocyte meiotic maturation, and early embryonic development. ATRX expression is dynamically regulated as evidenced by loss of the protein in metaphase II of meiosis. The downstream activation of meiosis via protein kinase A inhibition resulted in a similar decrease in ATRX protein expression. We demonstrate that the ATRX protein is detected in ubiquitin immuno-precipitates from germinal vesicle oocyte extracts and experimentally demonstrate that proteosomal degradation is responsible for the decreased expression of ATRX during meiosis. ATRX expression is significantly increased in response to gamma-irradiation induced DNA damage in oocytes and embryos. This increased expression is independent of p53 protein expression in apoptotic embryos, as determined by the expression of active caspase-3. Thus, regulation of ATRX protein expression impacts on G2-M progression and ultimately has consequences for cell survival.
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Affiliation(s)
| | - Trudee Fair
- UCD School of Agriculture and Food Science, Dublin, Ireland
| | - Carmel Hensey
- UCD School of Bimolecular and Biomedical Science, University College Dublin, Dublin, Ireland
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3
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Manzano C, Benzal MG, Zelarayán LI. Dynamics of steroid-induced oocyte maturation in three amphibian species: Mathematical modeling and simulation. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 329:589-596. [PMID: 30156763 DOI: 10.1002/jez.2222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/27/2018] [Indexed: 11/09/2022]
Abstract
Oocyte maturation in vertebrates involves morphological, biochemical, and functional changes through which meiosis, previously arrested in Profase I, is resumed. Within these changes, germinal vesicle breakdown (GVBD) constitutes morphological evidence of the resumption of the cellular cycle. Sex steroids (progestins and androgens) play a key role in oocyte maturation and are considered inducers of this process. The aims of this study were to analyze the effect of sex steroids on the oocyte maturation of amphibians and to model and simulate the dynamics of this process through the experimental data obtained. The oocytes of sexually mature females of Scinax fuscovarius, Pleurodema borellii, and Physalaemus biligonigerus were treated with different concentrations (0.001-1 µM) of sex steroids progesterone (P 4 ) and testosterone (T) for 24 hr. Dose- and time-response curves were performed with the results achieved. Sex steroids induced oocyte maturation in a dose-dependent manner in all three species. The dose at which the highest maturation percentage was found was 1 μM. No significant differences were observed between GVBD percentages of P 4 and T. However, time-response curves show that oocytes responded earlier and achieved higher GVBD percentages when treated with P 4 . Gompertz mathematical model was proposed in this study to simulate GVBD dynamics. This model properly fits the corresponding experimental data and allows the analysis of the behavior of oocyte maturation in amphibians and the quantification of parameters with biological meaning that are indicative of sex steroids efficiency in this process.
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Affiliation(s)
| | - Maria Graciela Benzal
- Facultad de Bioquímica, Química y Farmacia, Instituto de Matemática, Tucumán, Argentina
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4
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Yoon SY, Eum JH, Cha SK, Yoon TK, Lee DR, Lee WS. Prematuration Culture with Phosphodiesterase Inhibitors After Vitrification May Induce Recovery of Mitochondrial Activity in Vitrified Mouse Immature Oocytes. Biopreserv Biobank 2018; 16:296-303. [DOI: 10.1089/bio.2018.0010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Sook Young Yoon
- Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea
| | - Jin Hee Eum
- Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea
| | - Soo Kyoung Cha
- Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea
| | - Tae Ki Yoon
- Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea
| | - Dong Ryul Lee
- Department of Biomedical Science, College of Life Science, CHA University, Seongnam-si, Korea
| | - Woo Sik Lee
- Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul, Korea
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5
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Carvacho I, Piesche M, Maier TJ, Machaca K. Ion Channel Function During Oocyte Maturation and Fertilization. Front Cell Dev Biol 2018; 6:63. [PMID: 29998105 PMCID: PMC6028574 DOI: 10.3389/fcell.2018.00063] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 06/04/2018] [Indexed: 12/20/2022] Open
Abstract
The proper maturation of both male and female gametes is essential for supporting fertilization and the early embryonic divisions. In the ovary, immature fully-grown oocytes that are arrested in prophase I of meiosis I are not able to support fertilization. Acquiring fertilization competence requires resumption of meiosis which encompasses the remodeling of multiple signaling pathways and the reorganization of cellular organelles. Collectively, this differentiation endows the egg with the ability to activate at fertilization and to promote the egg-to-embryo transition. Oocyte maturation is associated with changes in the electrical properties of the plasma membrane and alterations in the function and distribution of ion channels. Therefore, variations on the pattern of expression, distribution, and function of ion channels and transporters during oocyte maturation are fundamental to reproductive success. Ion channels and transporters are important in regulating membrane potential, but also in the case of calcium (Ca2+), they play a critical role in modulating intracellular signaling pathways. In the context of fertilization, Ca2+ has been shown to be the universal activator of development at fertilization, playing a central role in early events associated with egg activation and the egg-to-embryo transition. These early events include the block of polyspermy, the completion of meiosis and the transition to the embryonic mitotic divisions. In this review, we discuss the role of ion channels during oocyte maturation, fertilization and early embryonic development. We will describe how ion channel studies in Xenopus oocytes, an extensively studied model of oocyte maturation, translate into a greater understanding of the role of ion channels in mammalian oocyte physiology.
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Affiliation(s)
- Ingrid Carvacho
- Department of Biology and Chemistry, Faculty of Basic Sciences, Universidad Católica del Maule, Talca, Chile
| | - Matthias Piesche
- Biomedical Research Laboratories, Medicine Faculty, Universidad Católica del Maule, Talca, Chile
| | - Thorsten J. Maier
- Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, Goethe-University Hospital, Frankfurt, Germany
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell-Medicine-Qatar, Education City, Qatar Foundation, Doha, Qatar
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6
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Nader N, Dib M, Courjaret R, Hodeify R, Machaca R, Graumann J, Machaca K. VLDL receptor regulates membrane progesterone receptor trafficking and non-genomic signaling. J Cell Sci 2018; 131:jcs.212522. [DOI: 10.1242/jcs.212522] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 04/17/2018] [Indexed: 11/20/2022] Open
Abstract
Progesterone mediates its physiological functions through activation of both transcription-coupled nuclear receptors and 7-transmembrane progesterone receptors (mPRs) that transduce progesterone's rapid non-genomic actions by coupling to various signaling modules. However, the immediate mechanisms of action downstream of mPRs remain in question. Herein we use an untargeted quantitative proteomics approach to identify mPR interactors to better define progesterone non-genomic signaling. Surprisingly, we identify the VLDL Receptor (VLDLR) as an mPR partner required for its plasma membrane localization. Knocking down VLDLR abolishes non-genomic progesterone signaling, a phenotype that is rescued by overexpressing VLDLR. Mechanistically, we show that the VLDLR is required for mPR trafficking from the ER to the Golgi. Taken together, our data define a novel function for the VLDLR as a trafficking chaperone required for the mPR subcellular localization and as such non-genomic progesterone-dependent signaling.
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Affiliation(s)
- Nancy Nader
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City – Qatar Foundation, Doha, Qatar
| | - Maya Dib
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City – Qatar Foundation, Doha, Qatar
| | - Raphael Courjaret
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City – Qatar Foundation, Doha, Qatar
| | - Rawad Hodeify
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City – Qatar Foundation, Doha, Qatar
| | - Raya Machaca
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City – Qatar Foundation, Doha, Qatar
| | - Johannes Graumann
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City – Qatar Foundation, Doha, Qatar
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City – Qatar Foundation, Doha, Qatar
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7
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Shi M, Cheng J, He Y, Jiang Z, Bodinga BM, Liu B, Chen H, Li Q. Effect of FH535 on in vitro
maturation of porcine oocytes by inhibiting WNT signaling pathway. Anim Sci J 2017; 89:631-639. [DOI: 10.1111/asj.12982] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 02/26/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Meihong Shi
- College of Animal Science and Technology; Northwest A&F University; Yangling Shaanxi China
| | - Jianyong Cheng
- College of Animal Science and Technology; Northwest A&F University; Yangling Shaanxi China
| | - Yamei He
- College of Animal Science and Technology; Northwest A&F University; Yangling Shaanxi China
| | - Zhongliang Jiang
- College of Animal Science and Technology; Northwest A&F University; Yangling Shaanxi China
| | - Bello M. Bodinga
- College of Animal Science and Technology; Northwest A&F University; Yangling Shaanxi China
| | - Boyang Liu
- College of Animal Science and Technology; Northwest A&F University; Yangling Shaanxi China
| | - Huali Chen
- College of Animal Science and Technology; Northwest A&F University; Yangling Shaanxi China
| | - Qingwang Li
- College of Animal Science and Technology; Northwest A&F University; Yangling Shaanxi China
- College of Environment and Chemistry Engineering; Yanshan University; Qinhuangdao Hebei China
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8
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Schaefer-Ramadan S, Hubrack S, Machaca K. Transition metal dependent regulation of the signal transduction cascade driving oocyte meiosis. J Cell Physiol 2017; 233:3164-3175. [DOI: 10.1002/jcp.26157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 08/14/2017] [Indexed: 12/19/2022]
Affiliation(s)
| | - Satanay Hubrack
- Department of Physiology and Biophysics; Weill Cornell Medicine-Qatar; Doha Qatar
| | - Khaled Machaca
- Department of Physiology and Biophysics; Weill Cornell Medicine-Qatar; Doha Qatar
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9
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Dupré AI, Haccard O, Jessus C. The greatwall kinase is dominant over PKA in controlling the antagonistic function of ARPP19 in Xenopus oocytes. Cell Cycle 2017; 16:1440-1452. [PMID: 28722544 DOI: 10.1080/15384101.2017.1338985] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The small protein ARPP19 plays a dual role during oocyte meiosis resumption. In Xenopus, ARPP19 phosphorylation at S109 by PKA is necessary for maintaining oocytes arrested in prophase of the first meiotic division. Progesterone downregulates PKA, leading to the dephosphorylation of ARPP19 at S109. This initiates a transduction pathway ending with the activation of the universal inducer of M-phase, the kinase Cdk1. This last step depends on ARPP19 phosphorylation at S67 by the kinase Greatwall. Hence, phosphorylated by PKA at S109, ARPP19 restrains Cdk1 activation while when phosphorylated by Greatwall at S67, ARPP19 becomes an inducer of Cdk1 activation. Here, we investigate the functional interplay between S109 and S67-phosphorylations of ARPP19. We show that both PKA and Gwl phosphorylate ARPP19 independently of each other and that Cdk1 is not directly involved in regulating the biological activity of ARPP19. We also show that the phosphorylation of ARPP19 at S67 that activates Cdk1, is dominant over the inhibitory S109 phosphorylation. Therefore our results highlight the importance of timely synchronizing ARPP19 phosphorylations at S109 and S67 to fully activate Cdk1.
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Affiliation(s)
- Aude-Isabelle Dupré
- a Sorbonne Universités, UPMC Univ Paris 06, CNRS, Biologie du développement - Institut de Biologie Paris Seine (LBD - IBPS) , Paris , France
| | - Olivier Haccard
- a Sorbonne Universités, UPMC Univ Paris 06, CNRS, Biologie du développement - Institut de Biologie Paris Seine (LBD - IBPS) , Paris , France
| | - Catherine Jessus
- a Sorbonne Universités, UPMC Univ Paris 06, CNRS, Biologie du développement - Institut de Biologie Paris Seine (LBD - IBPS) , Paris , France
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10
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Nader N, Courjaret R, Dib M, Kulkarni RP, Machaca K. Release from Xenopus oocyte prophase I meiotic arrest is independent of a decrease in cAMP levels or PKA activity. Development 2016; 143:1926-36. [PMID: 27122173 DOI: 10.1242/dev.136168] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/07/2016] [Indexed: 12/13/2022]
Abstract
Vertebrate oocytes arrest at prophase of meiosis I as a result of high levels of cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) activity. In Xenopus, progesterone is believed to release meiotic arrest by inhibiting adenylate cyclase, lowering cAMP levels and repressing PKA. However, the exact timing and extent of the cAMP decrease is unclear, with conflicting reports in the literature. Using various in vivo reporters for cAMP and PKA at the single-cell level in real time, we fail to detect any significant changes in cAMP or PKA in response to progesterone. More interestingly, there was no correlation between the levels of PKA inhibition and the release of meiotic arrest. Furthermore, we devised conditions whereby meiotic arrest could be released in the presence of sustained high levels of cAMP. Consistently, lowering endogenous cAMP levels by >65% for prolonged time periods failed to induce spontaneous maturation. These results argue that the release of oocyte meiotic arrest in Xenopus is independent of a reduction in either cAMP levels or PKA activity, but rather proceeds through a parallel cAMP/PKA-independent pathway.
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Affiliation(s)
- Nancy Nader
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar 24144
| | - Raphael Courjaret
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar 24144
| | - Maya Dib
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar 24144
| | - Rashmi P Kulkarni
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar 24144
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medicine Qatar, Education City - Qatar Foundation, Doha, Qatar 24144
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11
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Dupré A, Daldello EM, Nairn AC, Jessus C, Haccard O. Phosphorylation of ARPP19 by protein kinase A prevents meiosis resumption in Xenopus oocytes. Nat Commun 2015; 5:3318. [PMID: 24525567 PMCID: PMC4014304 DOI: 10.1038/ncomms4318] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 01/24/2014] [Indexed: 11/13/2022] Open
Abstract
During oogenesis, oocytes are arrested in prophase and resume meiosis by activating the kinase Cdk1 upon hormonal stimulation. In all vertebrates, release from prophase arrest relies on protein kinase A (PKA) downregulation and on the dephosphorylation of a long-sought but still unidentified substrate. Here we show that ARPP19 is the PKA substrate whose phosphorylation at serine 109 is necessary and sufficient for maintaining Xenopus oocytes arrested in prophase. By downregulating PKA, progesterone, the meiotic inducer in Xenopus, promotes partial dephosphorylation of ARPP19 that is required for the formation of a threshold level of active Cdk1. Active Cdk1 then initiates MPF autoamplification loop that occurs independently of both PKA and ARPP19 phosphorylation at serine 109 but requires the Greatwall-dependent phosphorylation of ARPP19 at serine 67. Therefore, ARPP19 stands at a crossroads in the meiotic M-phase control network by integrating differential effects of PKA and Greatwall, two essential kinases for meiosis resumption.
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Affiliation(s)
- Aude Dupré
- 1] Sorbonne Universités, UPMC Univ Paris 06, UMR7622-Biologie du Développement, Paris F-75005, France [2] CNRS, UMR7622-Biologie du Développement, Paris F-75005, France [3]
| | - Enrico M Daldello
- 1] Sorbonne Universités, UPMC Univ Paris 06, UMR7622-Biologie du Développement, Paris F-75005, France [2] CNRS, UMR7622-Biologie du Développement, Paris F-75005, France [3] Sorbonne Universités, UPMC Univ Paris 06, IFD, 4 Place Jussieu, cedex 05, Paris 75252, France [4]
| | - Angus C Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut 06508, USA
| | - Catherine Jessus
- 1] Sorbonne Universités, UPMC Univ Paris 06, UMR7622-Biologie du Développement, Paris F-75005, France [2] CNRS, UMR7622-Biologie du Développement, Paris F-75005, France
| | - Olivier Haccard
- 1] Sorbonne Universités, UPMC Univ Paris 06, UMR7622-Biologie du Développement, Paris F-75005, France [2] CNRS, UMR7622-Biologie du Développement, Paris F-75005, France
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12
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Nader N, Dib M, Daalis A, Kulkarni RP, Machaca K. Role for endocytosis of a constitutively active GPCR (GPR185) in releasing vertebrate oocyte meiotic arrest. Dev Biol 2014; 395:355-66. [PMID: 25220151 DOI: 10.1016/j.ydbio.2014.08.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 08/04/2014] [Accepted: 08/28/2014] [Indexed: 01/20/2023]
Abstract
Vertebrate oocytes are naturally arrested at prophase of meiosis I for sustained periods of time before resuming meiosis in a process called oocyte maturation that prepares the egg for fertilization. Members of the constitutively active GPR3/6/12 family of G-protein coupled receptors represent important mediators of meiotic arrest. In the frog oocyte the GPR3/12 homolog GPRx (renamed GPR185) has been shown to sustain meiotic arrest by increasing intracellular cAMP levels through GαSβγ. Here we show that GPRx is enriched at the cell membrane (~80%), recycles through an endosomal compartment at steady state, and loses its ability to signal once trapped intracellularly. Progesterone-mediated oocyte maturation is associated with significant internalization of both endogenous and overexpressed GPRx. Furthermore, a GPRx mutant that does not internalize in response to progesterone is significantly more efficient than wild-type GPRx at blocking oocyte maturation. Collectively our results argue that internalization of the constitutively active GPRx is important to release oocyte meiotic arrest.
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Affiliation(s)
- Nancy Nader
- Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City - Qatar Foundation, Doha, Qatar
| | - Maya Dib
- Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City - Qatar Foundation, Doha, Qatar
| | - Arwa Daalis
- Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City - Qatar Foundation, Doha, Qatar
| | - Rashmi P Kulkarni
- Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City - Qatar Foundation, Doha, Qatar
| | - Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City - Qatar Foundation, Doha, Qatar.
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13
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Turcheniuk K, Khanal M, Motorina A, Subramanian P, Barras A, Zaitsev V, Kuncser V, Leca A, Martoriati A, Cailliau K, Bodart JF, Boukherroub R, Szunerits S. Insulin loaded iron magnetic nanoparticle–graphene oxide composites: synthesis, characterization and application for in vivo delivery of insulin. RSC Adv 2014. [DOI: 10.1039/c3ra46307a] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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14
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O'Shea L, Fair T, Hensey C. Aven is dynamically regulated during Xenopus oocyte maturation and is required for oocyte survival. Cell Death Dis 2013; 4:e908. [PMID: 24201807 PMCID: PMC3847313 DOI: 10.1038/cddis.2013.435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 07/17/2013] [Accepted: 09/11/2013] [Indexed: 11/09/2022]
Abstract
We have analyzed the expression and function of the cell death and cell cycle regulator Aven in Xenopus. Analysis of Xenopus Aven expression in oocytes and embryos revealed a band close to the predicted molecular weight of the protein (36 kDa) in addition to two bands of higher molecular weight (46 and 49 kDa), one of which was determined to be due to phosphorylation of the protein. The protein is primarily detected in the cytoplasm of oocytes and is tightly regulated during meiotic and mitotic cell cycles. Progesterone stimulation of oocytes resulted in a rapid loss of Aven expression with the protein levels recovering before germinal vesicle breakdown (GVBD). This loss of Aven is required for the G2–M1 cell cycle transition. Aven morpholino knockdown experiments revealed that early depletion of the protein increases progesterone sensitivity and facilitates GVBD, but prolonged depletion of Aven results in caspase-3 activation and oocyte death by apoptosis. Phosphorylated Aven (46 kDa) was found to bind Bcl-xL in oocytes, but this interaction was lost in apoptotic oocytes. Thus, Aven alters progesterone sensitivity in oocytes and is critical for oocyte survival.
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Affiliation(s)
- L O'Shea
- UCD School of Bimolecular and Biomedical Science, UCD Conway Institute of Biomolecular and Biomedical Research, Belfield, Dublin 4, Ireland
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15
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Lee B, Palermo G, Machaca K. Downregulation of store-operated Ca2+ entry during mammalian meiosis is required for the egg-to-embryo transition. J Cell Sci 2013; 126:1672-81. [PMID: 23424198 DOI: 10.1242/jcs.121335] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A specialized Ca(2+) transient at fertilization represents the universal driver for the egg-to-embryo transition. Ca(2+) signaling remodels during oocyte maturation to endow the egg with the capacity to produce the specialized Ca(2+) transient at fertilization, which takes the form of a single (e.g. Xenopus) or multiple (e.g. mouse) Ca(2+) spikes depending on the species. Store-operated Ca(2+) entry (SOCE) is the predominant Ca(2+) influx pathway in vertebrate oocytes, and in Xenopus SOCE completely inactivates during meiosis. Here, we show that SOCE is downregulated during mouse meiosis, but remains active in mature metaphase II eggs. SOCE inhibition is due to a decreased ability of the Ca(2+) sensor STIM1 to translocate to the cortical endoplasmic reticulum domain and due to internalization of Orai1. Reversing SOCE downregulation by overexpression of STIM1 and Orai1 prolongs the Ca(2+) oscillations at egg activation and disrupts the egg-to-embryo transition. Thus, SOCE downregulation during mammalian oocyte maturation is a crucial determinant of the fertilization-specific Ca(2+) transient, egg activation and early embryonic development.
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Affiliation(s)
- Bora Lee
- Center for Reproductive Medicine and Infertility, Weill Cornell Medical College, New York, NY 10021, USA
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16
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Nader N, Kulkarni RP, Dib M, Machaca K. How to make a good egg!: The need for remodeling of oocyte Ca(2+) signaling to mediate the egg-to-embryo transition. Cell Calcium 2012; 53:41-54. [PMID: 23266324 DOI: 10.1016/j.ceca.2012.11.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 11/26/2012] [Accepted: 11/27/2012] [Indexed: 11/19/2022]
Abstract
The egg-to-embryo transition marks the initiation of multicellular organismal development and is mediated by a specialized Ca(2+) transient at fertilization. This explosive Ca(2+) signal has captured the interest and imagination of scientists for many decades, given its cataclysmic nature and necessity for the egg-to-embryo transition. Learning how the egg acquires the competency to generate this Ca(2+) transient at fertilization is essential to our understanding of the mechanisms controlling egg and the transition to embryogenesis. In this review we discuss our current knowledge of how Ca(2+) signaling pathways remodel during oocyte maturation in preparation for fertilization with a special emphasis on the frog oocyte as additional reviews in this issue will touch on this in other species.
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Affiliation(s)
- Nancy Nader
- Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar (WCMC-Q), Education City, Qatar Foundation, Qatar
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Mohanty BK, Gupta BL. A marked animal-vegetal polarity in the localization of Na(+),K(+) -ATPase activity and its down-regulation following progesterone-induced maturation. Mol Reprod Dev 2011; 79:138-60. [PMID: 22213374 DOI: 10.1002/mrd.22012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 11/22/2011] [Indexed: 01/01/2023]
Abstract
The stage-VI Xenopus oocyte has a very distinct animal-vegetal polarity with structural and functional asymmetry. In this study, we show the expression and distribution pattern of Na(+),K(+) -ATPase in stage-VI oocytes, and its changes following progesterone-induced maturation. Using enzyme-specific electron microscopy phosphatase histochemistry, [(3) H]-ouabain autoradiography, and immunofluorescence cytochemistry at light microscopic level, we find that Na(+),K(+) -ATPase activity is mainly confined to the animal hemisphere. Electron microscopy histochemical results also suggest that polarized distribution of Na(+),K(+) -ATPase activity persists following progesterone-induced maturation, and it becomes gradually more polarized towards the animal pole. The time course following progesterone-induced maturation suggests that there is an initial up-regulation and then gradual down-regulation of Na(+),K(+) -ATPase activity leading to germinal vesicle breakdown (GVBD). By GVBD, the Na(+),K(+) -ATPase activity is completely down-regulated due to endocytotic removal of pump molecules from the plasma membrane into the sub-cortical region of the oocyte. This study provides the first direct evidence for a marked asymmetric localization of Na(+),K(+) -ATPase activity in any vertebrate oocyte. Here, we propose that such asymmetry in Na(+),K(+) -ATPase activity in stage-VI oocytes, and their down-regulation following progesterone-induced maturation, is likely to have a role in the active state of the germinal vesicle in stage-VI oocytes and chromosomal condensation after GVBD.
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18
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Lee HS, Kim EY, Lee KA. Changes in gene expression associated with oocyte meiosis after Obox4 RNAi. Clin Exp Reprod Med 2011; 38:68-74. [PMID: 22384421 PMCID: PMC3283059 DOI: 10.5653/cerm.2011.38.2.68] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 05/31/2011] [Accepted: 06/03/2011] [Indexed: 12/03/2022] Open
Abstract
Objective Previously, we found that oocyte specific homeobox (Obox) 4 plays significant role in completion of meiosis specifically at meiosis I-meiosis II (MI-MII) transition. The purpose of this study was to determine the mechanism of action of Obox4 in oocyte maturation by evaluating downstream signal networking. Methods The Obox4 dsRNA was prepared by in vitro transcription and microinjected into the cytoplasm of germinal vesicle oocytes followed by in vitro maturation in the presence or absence of 0.2 mM 3-isobutyl-1-metyl-xanthine. Total RNA was extracted from 200 oocytes of each group using a PicoPure RNA isolation kit then amplified two-rounds. The probe hybridization and data analysis were used by Affymetrix GeneChip® Mouse Genome 430 2.0 array and GenPlex 3.0 (ISTECH, Korea) software, respectively. Results Total 424 genes were up (n=80) and down (n=344) regulated after Obox4 RNA interference (RNAi). Genes mainly related to metabolic pathways and mitogen-activated protein kinase (MAPK) signaling pathway was changed. Among the protein kinase C (PKC) isoforms, PKC-alpha, beta, gamma were down-regulated and especially the MAPK signaling pathway PKC-gamma was dramatically decreased by Obox4 RNAi. In the cell cycle pathway, we evaluated the expression of genes involved in regulation of chromosome separation, and found that these genes were down-regulated. It may cause the aberrant chromosome segregation during MI-MII transition. Conclusion From the results of this study, it is concluded that Obox4 is important upstream regulator of the PKC and anaphase-promoting complex action for maintaining intact germinal vesicle.
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Affiliation(s)
- Hyun-Seo Lee
- Department of Biomedical Science, College of Life Science, CHA University, Seoul, Korea
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19
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20
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Machaca K. Ca(2+) signaling, genes and the cell cycle. Cell Calcium 2010; 48:243-50. [PMID: 21084120 DOI: 10.1016/j.ceca.2010.10.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 10/06/2010] [Accepted: 10/06/2010] [Indexed: 11/30/2022]
Abstract
Changes in the concentration and spatial distribution of Ca(2+) ions in the cytoplasm constitute a ubiquitous intracellular signaling module in cellular physiology. With the advent of Ca(2+) dyes that allow direct visualization of Ca(2+) transients, combined with powerful experimental tools such as electrophysiological recordings, intracellular Ca(2+) transients have been implicated in practically every aspect of cellular physiology, including cellular proliferation. Ca(2+) signals are associated with different phases of the cell cycle and interfering with Ca(2+) signaling or downstream pathways often disrupts progression of the cell cycle. Although there exists a dependence between Ca(2+) signals and the cell cycle the mechanisms involved are not well defined and given the cross-talk between Ca(2+) and other signaling modules, it is difficult to assess the exact role of Ca(2+) signals in cell cycle progression. Two exceptions however, include fertilization and T-cell activation, where well-defined roles for Ca(2+) signals in mediating progression through specific stages of the cell cycle have been clearly established. In the case of T-cell activation Ca(2+) regulates entry into the cell cycle through the induction of gene transcription.
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Affiliation(s)
- Khaled Machaca
- Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar (WCMC-Q), PO Box 24144, Education City - Qatar Foundation, Doha, Qatar.
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21
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Zhang Y, Zhang Z, Xu XY, Li XS, Yu M, Yu AM, Zong ZH, Yu BZ. Protein kinase a modulates Cdc25B activity during meiotic resumption of mouse oocytes. Dev Dyn 2008; 237:3777-86. [DOI: 10.1002/dvdy.21799] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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22
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Friend K, Kolev NG, Shu MD, Steitz JA. Minor-class splicing occurs in the nucleus of the Xenopus oocyte. RNA (NEW YORK, N.Y.) 2008; 14:1459-62. [PMID: 18567814 PMCID: PMC2491479 DOI: 10.1261/rna.1119708] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
A small fraction of premessenger RNA introns in certain eukaryotes is excised by the minor spliceosome, which contains low-abundance small nuclear ribonucleoproteins (snRNPs). Recently, it was suggested that minor-class snRNPs are localized to and function in the cytoplasm of vertebrate cells. To test whether U12-type splicing occurs in the cytoplasm of Xenopus oocytes, we performed microinjections of the well-characterized P120 minor-class splicing substrate into the nucleus or into the cytoplasm. Our results demonstrate that accurate splicing of this U12-dependent intron occurs exclusively in the nuclear compartment of the oocyte, where U12 and U6atac snRNPs are primarily localized. We further demonstrate that splicing of both a major-class and a minor-class intron is inhibited after nuclear envelope breakdown during meiosis.
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Involvement of GABAA receptor in Bufo arenarum oocyte maturation. ZYGOTE 2008; 16:135-44. [PMID: 18405434 DOI: 10.1017/s0967199408004656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Amphibian oocytes meiotic arrest is released under the stimulus of progesterone; this hormone interacts with the oocyte surface and starts a cascade of events leading to the activation of a cytoplasmic maturation promoting factor (MPF) that induces germinal vesicle breakdown (GVBD), chromosome condensation and extrusion of the first polar body. The aim of this work was to determine whether the activation of a GABAA receptor is able to induce GVBD in fully grown denuded oocytes of Bufo arenarum and to analyse its possible participation in progesterone-induced maturation. We also evaluated the role of purines and phospholipids in the maturation process induced by a GABAA receptor agonist such as muscimol. Our results indicated that the activation of the GABAA receptor by muscimol induces maturation in a dose- and time-dependent manner and that this activation is a genuine maturation that enables oocytes to form pronuclei. Assays with a receptor antagonist, picrotoxine, showed that the maturation induced by muscimol was inhibited. Treatment with picrotoxine, however, shows that the participation of GABAA receptor in progesterone-induced maturation is not significant. In addition, our results indicate that high intracellular levels of purines obtained by the use of db-AMPc and theophylline or the inhibition of the phosphatidylinositol 4,5-bisphosphate (PIP2 hydrolysis by neomycin and PIP2 turn over by LiCl, respectively, inhibited the maturation induced by muscimol. Treatment with H-7 indicated, however, that PKC activation is not necessary for GVBD induced by the GABAA receptor agonist. Results suggest that the transduction pathway used by the GABAA receptor to induce maturation is different from those used by progesterone.
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24
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Horner VL, Wolfner MF. Transitioning from egg to embryo: Triggers and mechanisms of egg activation. Dev Dyn 2008; 237:527-44. [DOI: 10.1002/dvdy.21454] [Citation(s) in RCA: 150] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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25
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Oz M, Yang KH, Dinc M, Shippenberg TS. The endogenous cannabinoid anandamide inhibits cromakalim-activated K+ currents in follicle-enclosed Xenopus oocytes. J Pharmacol Exp Ther 2007; 323:547-54. [PMID: 17682128 DOI: 10.1124/jpet.107.125336] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The effect of the endogenous cannabinoid anandamide on K(+) currents activated by the ATP-sensitive potassium (K(ATP)) channel opener cromakalim was investigated in follicle-enclosed Xenopus oocytes using the two-electrode voltage-clamp technique. Anandamide (1-90 microM) reversibly inhibited cromakalim-induced K(+) currents, with an IC(50) value of 8.1 +/- 2 microM. Inhibition was noncompetitive and independent of membrane potential. Coapplication of anandamide with the cannabinoid type 1 (CB(1)) receptor antagonist N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboximide hydrochloride (SR 141716A) (1 microM), the CB(2) receptor antagonist N-[(1S)endo-1,3,3-trimethyl bicyclo heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide (SR144528) (1 microM), or pertussis toxin (5 microg/ml) did not alter the inhibitory effect of anandamide, suggesting that known cannabinoid receptors are not involved in anandamide inhibition of K(+) currents. Similarly, neither the amidohydrolase inhibitor phenylmethylsulfonyl fluoride (0.2 mM) nor the cyclooxygenase inhibitor indomethacin (5 microM) affected anandamide inhibition of K(+) currents, suggesting that the effects of anandamide are not mediated by its metabolic products. In radioligand binding studies, anandamide inhibited the specific binding of the K(ATP) ligand [(3)H]glibenclamide in the oocyte microsomal fractions, with an IC(50) value of 6.3 +/- 0.4 microM. Gonadotropin-induced oocyte maturation and the cromakalim-acceleration of progesterone-induced oocyte maturation were significantly inhibited in the presence of 10 microM anandamide. Collectively, these results indicate that cromakalim-activated K(+) currents in follicular cells of Xenopus oocytes are modulated by anandamide via a cannabinoid receptor-independent mechanism and that the inhibition of these channels by anandamide alters the responsiveness of oocytes to gonadotropin and progesterone.
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Affiliation(s)
- Murat Oz
- National Institute on Drug Abuse/Intramural Research Program Integrative Neuroscience Section, 333 Cassell Dr., Baltimore, MD 21224, USA.
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26
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Coll O, Morales A, Fernández-Checa JC, Garcia-Ruiz C. Neutral sphingomyelinase-induced ceramide triggers germinal vesicle breakdown and oxidant-dependent apoptosis in Xenopus laevis oocytes. J Lipid Res 2007; 48:1924-35. [PMID: 17556754 DOI: 10.1194/jlr.m700069-jlr200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Ceramide regulates many cellular processes, including cell growth, differentiation, and apoptosis. Although the effects of exogenous bacterial neutral sphingomyelinase (SMase) in Xenopus laevis oocytes have been investigated, its microinjection into oocytes has not been reported previously. Thus, we compared the incubation versus microinjection of the neutral Bacillus cereus sphingomyelinase (bSMase) to examine whether the topology of ceramide generation determines its effects on the fate of oocytes. In agreement with previous findings, incubation of mature stage VI oocytes with bSMase increased ceramide levels in oocyte extracts over time, causing the germinal vesicle breakdown indicative of maturation, without evidence of cytotoxicity. In contrast, bSMase microinjection, which increased ceramide levels in a time- and dose-dependent manner, resulted in oocyte apoptosis characterized by reactive oxygen species (ROS) generation, reduced glutathione (GSH) depletion in cytosol and mitochondria, release of cytochrome c and Smac/Diablo from mitochondria, and caspase-3 activation. Microinjection of acidic SMase from human placenta recapitulated the apoptotic effects of bSMase microinjection. Preincubation of oocytes with GSH-ethyl ester before bSMase microinjection prevented ROS generation and mitochondrial downstream events, thus protecting oocytes from bSMase-induced death. These findings show a divergent action of bSMase-induced ceramide on oocyte maturation or apoptosis depending on the intracellular site where ceramide is generated.
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Affiliation(s)
- Olga Coll
- Hospital Clínic i Provincial and Centro de Investigación Biomédica en Red de Enfermedades Hepaticas y Digestivas, Instituto Investigaciones Biomédicas Barcelona, Consejo Superior de Investigaciones Científicas, 08036-Barcelona, Spain
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27
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Toranzo GS, Oterino J, Zelarayán L, Bonilla F, Bühler MI. Spontaneous and LH-induced maturation inBufo arenarumoocytes: importance of gap junctions. ZYGOTE 2007; 15:65-80. [PMID: 17391547 DOI: 10.1017/s0967199406004023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARYIt has been demonstrated inBufo arenarumthat fully grown oocytes are capable of meiotic resumption in the absence of a hormonal stimulus if they are deprived of their follicular envelopes. This event, called spontaneous maturation, only takes place in oocytes collected during the reproductive period, which have a metabolically mature cytoplasm.InBufo arenarum, progesterone acts on the oocyte surface and causes modifications in the activities of important enzymes, such as a decrease in the activity of adenylate cyclase (AC) and the activation of phospholipase C (PLC). PLC activation leads to the formation of diacylglycerol (DAG) and inositol triphosphate (IP3), second messengers that activate protein kinase C (PKC) and cause an increase in intracellular Ca2+. Recent data obtained fromBufo arenarumshow that progesterone-induced maturation causes significant modifications in the level and composition of neutral lipids and phospholipids of whole fully grown ovarian oocytes and of enriched fractions in the plasma membrane. In amphibians, the luteinizing hormone (LH) is responsible for meiosis resumption through the induction of progesterone production by follicular cells.The aim of this work was to study the importance of gap junctions in the spontaneous and LH-induced maturation inBufo arenarumoocytes. During the reproductive period,Bufo arenarumoocytes are capable of undergoing spontaneous maturation in a similar way to mammalian oocytes while, during the non-reproductive period, they exhibit the behaviour that is characteristic of amphibian oocytes, requiring progesterone stimulation for meiotic resumption (incapable oocytes).This different ability to mature spontaneously is coincident with differences in the amount and composition of the phospholipids in the oocyte membranes. Capable oocytes exhibit in their membranes higher quantities of phospholipids than incapable oocytes, especially of PC and PI, which are precursors of second messengers such as DAG and IP3.The uncoupling of the gap junctions with 1-octanol or halothane fails to induce maturation in follicles from the non-reproductive period, whose oocytes are incapable of maturing spontaneously. However, if the treatment is performed during the reproductive period, with oocytes capable of undergoing spontaneous maturation, meiosis resumption occurs in high percentages, similar to those obtained by manual defolliculation.Interestingly, results show that LH is capable of inducing GVBD in both incapable oocytes and in oocytes capable of maturing spontaneously as long as follicle cells are present, which would imply the need for a communication pathway between the oocyte and the follicle cells. This possibility was analysed by combining LH treatment with uncoupling agents such as 1-octanol or halothane. Results show that maturation induction with LH requires a cell–cell coupling, as the uncoupling of the gap junctions decreases GVBD percentages. Experiments with LH in the presence of heparin, BAPTA/AM and theophylline suggest that the hormone could induce GVBD by means of the passage of IP3or Ca2+through the gap junctions, which would increase the Ca2+level in the oocyte cytoplasm and activate phosphodiesterase (PDE), thus contributing to the decrease in cAMP levels and allowing meiosis resumption.
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Affiliation(s)
- G Sánchez Toranzo
- Departamento de Biología del Desarrollo, San Miguel de Tucumán, Argentina
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28
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Abstract
Oocyte maturation is an essential cellular differentiation pathway that prepares the egg for activation at fertilization leading to the initiation of embryogenesis. An integral attribute of oocyte maturation is the remodeling of Ca2+ signaling pathways endowing the egg with the capacity to produce a specialized Ca2+ transient at fertilization that is necessary and sufficient for egg activation. Consequently, mechanistic elucidation of Ca2+ signaling differentiation during oocyte maturation is fundamental to our understanding of egg activation, and offers a glimpse into Ca2+ signaling regulation during the cell cycle.
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Affiliation(s)
- Khaled Machaca
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
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LaChapelle AM, Ruygrok ML, Toomer M, Oost JJ, Monnie ML, Swenson JA, Compton AA, Stebbins-Boaz B. The hormonal herbicide, 2,4-dichlorophenoxyacetic acid, inhibits Xenopus oocyte maturation by targeting translational and post-translational mechanisms. Reprod Toxicol 2007; 23:20-31. [PMID: 17055699 DOI: 10.1016/j.reprotox.2006.08.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 07/21/2006] [Accepted: 08/22/2006] [Indexed: 11/16/2022]
Abstract
The widely used hormonal herbicide, 2,4-dichlorophenoxyacetic acid, blocks meiotic maturation in vitro and is thus a potential environmental endocrine disruptor with early reproductive effects. To test whether maturation inhibition was dependent on protein kinase A, an endogenous maturation inhibitor, oocytes were microinjected with PKI, a specific PKA inhibitor, and exposed to 2,4-D. Oocytes failed to mature, suggesting that 2,4-D is not dependent on PKA activity and likely acts on a downstream target, such as Mos. De novo synthesis of Mos, which is triggered by mRNA poly(A) elongation, was examined. Oocytes were microinjected with radiolabelled in vitro transcripts of Mos RNA and exposed to progesterone and 2,4-D. RNA analysis showed progesterone-induced polyadenylation as expected but none with 2,4-D. 2,4-D-activated MAPK was determined to be cytoplasmic in localization studies but poorly induced Rsk2 phosphorylation and activation. In addition to inhibition of the G2/M transition, 2,4-D caused abrupt reduction of H1 kinase activity in MII phase oocytes. Attempts to rescue maturation in oocytes transiently exposed to 2,4-D failed, suggesting that 2,4-D induces irreversible dysfunction of the meiotic signaling mechanism.
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Charlesworth A, Wilczynska A, Thampi P, Cox LL, MacNicol AM. Musashi regulates the temporal order of mRNA translation during Xenopus oocyte maturation. EMBO J 2006; 25:2792-801. [PMID: 16763568 PMCID: PMC1500856 DOI: 10.1038/sj.emboj.7601159] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Accepted: 04/28/2006] [Indexed: 11/08/2022] Open
Abstract
A strict temporal order of maternal mRNA translation is essential for meiotic cell cycle progression in oocytes of the frog Xenopus laevis. The molecular mechanisms controlling the ordered pattern of mRNA translational activation have not been elucidated. We report a novel role for the neural stem cell regulatory protein, Musashi, in controlling the translational activation of the mRNA encoding the Mos proto-oncogene during meiotic cell cycle progression. We demonstrate that Musashi interacts specifically with the polyadenylation response element in the 3' untranslated region of the Mos mRNA and that this interaction is necessary for early Mos mRNA translational activation. A dominant inhibitory form of Musashi blocks maternal mRNA cytoplasmic polyadenylation and meiotic cell cycle progression. Our data suggest that Musashi is a target of the initiating progesterone signaling pathway and reveal that late cytoplasmic polyadenylation element-directed mRNA translation requires early, Musashi-dependent mRNA translation. These findings indicate that Musashi function is necessary to establish the temporal order of maternal mRNA translation during Xenopus meiotic cell cycle progression.
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Affiliation(s)
- Amanda Charlesworth
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Anna Wilczynska
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Prajitha Thampi
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Linda L Cox
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Angus M MacNicol
- Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- The Arkansas Cancer Research Center, University of Arkansas for Medical Sciences, Little Rock, AR, USA
- Department of Neurobiology and Developmental Sciences, The Arkansas Cancer Research Center, Slot 814, University of Arkansas for Medical Sciences, 4301 West Markham, Little Rock, AR 72205, USA. Tel.: +1 501 686 8164; Fax: +1 501 686 6517; E-mail:
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Abstract
Xenopus laevis oocytes are popular cells in experimental biology. Fully grown oocytes are large (approximately 1.3-mm diameter) with an enormous nucleus (approximately 300-microm diameter). Oocytes are generally isolated by either manual dissection (manual defolliculation) or enzymatic (mainly with collagenase preparations) digestion of the extracellular connective tissues. In this chapter, we describe both procedures, which are routinely used in our laboratory. However, manual defolliculation does not actually remove the innermost layer of follicle cells, which are anchored to the vitelline membrane. To remove these follicle cells, further mechanical or enzymatic treatment is required. On the other hand, many have experienced nonspecific effects with collagenase-treated oocytes, including spontaneous oocyte maturation and reduced oocyte health. We discuss possible explanations and solutions to these problems. Finally, we also describe procedures we employ routinely to isolate oocyte nuclei and enucleated oocytes.
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Affiliation(s)
- X Shawn Liu
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ontario, Canada
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Abstract
In meiotic cell cycles, meiosis I (MI) is followed by meiosis II (MII) without an intervening S phase, whereas in mitotic cell cycles, an S phase necessarily alternates with an M phase. For the study of mitotic cell cycles, extracts prepared from unfertilized and parthenogenetically activated Xenopus eggs have been very useful as they can perform the progression of mitotic cycles in vitro. To establish a cell-free system to study the regulatory mechanisms of meiotic transition from MI to MII, extracts have been prepared from maturing Xenopus oocytes isolated from ovaries, stimulated with progesterone to induce the resumption of meiosis, and arrested at meiotic metaphase I by cold treatment. In oocyte extracts, the activity of cyclin B-Cdc2 complexes, the M phase inducer, fluctuates in the same manner as it does in maturing oocytes during the MI to MII transition period. By the use of oocyte extracts, it has been found that incomplete inactivation of Cdc2 at the end of MI is required for meiotic M-M transition. The meiotic extract should provide a useful tool to elucidate molecular mechanisms of meiotic M to M transition, including a role of Mos/mitogen-activated protein kinase cascade in the suppression of S phase entry after MI exit. In this chapter, we describe methods for the preparation and the uses of meiotic extracts. As a comparison, we also include a protocol for the preparation of mitotic extracts.
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Affiliation(s)
- Keita Ohsumi
- Laboratory of Cell and Developmental Biology, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan
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Morrill GA, Erlichman J, Gutierrez-Juarez R, Kostellow AB. The steroid-binding subunit of the Na/K-ATPase as a progesterone receptor on the amphibian oocyte plasma membrane. Steroids 2005; 70:933-45. [PMID: 16165176 DOI: 10.1016/j.steroids.2005.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 06/29/2005] [Accepted: 07/05/2005] [Indexed: 11/20/2022]
Abstract
Progesterone acts at a plasma membrane receptor on the Rana oocyte to initiate meiosis. A cascade of lipid messengers occurs within seconds, followed by sequential changes in membrane phospholipid composition. We now show that progesterone binding to the plasma membrane increases continuously over the first 4 h. Subsequently, about 60% of the total plasma membrane and > 90% of membrane-bound progesterone, ouabain binding sites, and Na/K-ATPase activity are internalized. Until the completion of membrane internalization, oocytes must be continuously exposed to nanomolar concentrations of exogenous progesterone for meiosis to continue. The membrane-bound progesterone remains unchanged, whereas microinjected [(3)H]progesterone is rapidly metabolized. We find that progesterone and the plant steroid ouabain compete for one of two ouabain binding sites on the oocyte surface. Ouabain blocks progesterone action and inhibits subsequent meiosis if added at any time during the first 4-5 h. Western blots of SDS/PAGE extracts of isolated oocyte plasma membranes contain a -110 kDa band which binds an antibody to the steroid-binding c-terminal domain in rat and human PR. The number of binding sites and K(d) for progesterone binding to the plasma membrane is comparable to those for low-affinity ouabain binding to the alpha-subunit of the Na/K-ATPase (112 kDa). Our results suggest that progesterone binding to the ouabain binding site on the N-terminal region of the alpha-subunit of Na/K-ATPase may modulate early plasma membrane events over the first 4-6 h. Progesterone may thus act in part through the plasma membrane Na/K-ATPase signaling system.
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Affiliation(s)
- Gene A Morrill
- Department of Physiology & Biophysics, Yeshiva University, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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Traverso JM, Donnay I, Lequarre AS. Effects of polyadenylation inhibition on meiosis progression in relation to the polyadenylation status of cyclins A2 and B1 during in vitro maturation of bovine oocytes. Mol Reprod Dev 2005; 71:107-14. [PMID: 15736128 DOI: 10.1002/mrd.20247] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The control of protein synthesis during maturation in oocytes is mainly exerted through cytoplasmic polyadenylation of stored mRNAs. We first analyzed the polyadenylation status of cyclins A2 and B1 during in vitro maturation (IVM) of bovine oocytes, using Rapid Amplification of cDNA Ends-Polyadenylation Technique (RACE-PAT). An inconstant elongation of the poly(A) tail was observed for cyclin A2 transcripts after maturation, while a constant lengthening was observed for cyclin B1, occurring during the first 12 hr of incubation. We then evaluated the effects of the polyadenylation inhibitor 3'-deoxyadenosine (3'-dA), on polyadenylation and nuclear maturation. The presence of 0.02 mM 3'-dA during the whole incubation period or from 6 hr after its beginning completely prevented meiosis progression in 100% of the oocytes. Polyadenylation of cyclin B1 was also completely prevented when 3'-dA was added at 0 hr, and greatly reduced when added at 6 hr. When 3'-dA was added at 12 hr, around metaphase I (MI), 46.9% of the oocytes have reached metaphase II (MII, vs. 78.8% in the control group) at 24 hr. The use of the same concentration of 3'-deoxyguanosine (3'-dG), that impairs transcription but not polyadenylation, did not affect cyclins polyadenylation, nor nuclear maturation, whatever was the timing of addition. These results suggest that the polyadenylation of cyclin B1 could be related to the first peak of activity of MPF, occurring around MI (10-12 hr after the onset of the maturation period). They also show that, in our culture conditions, inhibition of polyadenylation prevents meiosis progression, especially up to the MI stage, while inhibition of transcription does not.
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Affiliation(s)
- Juan M Traverso
- Veterinary Unit, Institut des Sciences de la Vie, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
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Sheng Y, Wang L, Liu XS, Montplaisir V, Tiberi M, Baltz JM, Liu XJ. A serotonin receptor antagonist induces oocyte maturation in both frogs and mice: evidence that the same G protein-coupled receptor is responsible for maintaining meiosis arrest in both species. J Cell Physiol 2005; 202:777-86. [PMID: 15499574 DOI: 10.1002/jcp.20170] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Accumulating evidence has indicated that vertebrate oocytes are arrested at late prophase (G2 arrest) by a G protein coupled receptor (GpCR) that activates adenylyl cyclases. However, the identity of this GpCR or its regulation in G2 oocytes is unknown. We demonstrated that ritanserin (RIT), a potent antagonist of serotonin receptors 5-HT2R and 5-HT7R, released G2 arrest in denuded frog oocytes, as well as in follicle-enclosed mouse oocytes. In contrast to RIT, several other serotonin receptor antagonists (mesulergine, methiothepine, and risperidone) had no effect on oocyte maturation. The unique ability of RIT, among serotonergic antagonists, to induce GVBD did not match the antagonist profile of any known serotonin receptors including Xenopus 5-HT7R, the only known G(s)-coupled serotonin receptor cloned so far in this species. Unexpectedly, injection of x5-HT7R mRNA in frog oocytes resulted in hormone-independent frog oocyte maturation. The addition of exogenous serotonin abolished x5-HT7R-induced oocyte maturation. Furthermore, the combination of x5-HT7R and exogenous serotonin potently inhibited progesterone-induced oocyte maturation. These results provide the first evidence that a G-protein coupled receptor related to 5-HT7R may play a pivotal role in maintaining G2 arrest in vertebrate oocytes.
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Affiliation(s)
- Yinglun Sheng
- Ottawa Health Research Institute, Ottawa Hospital, Ottawa, Canada
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36
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Sheng Y, Montplaisir V, Liu XJ. Co-operation of Gsalpha and Gbetagamma in maintaining G2 arrest in Xenopus oocytes. J Cell Physiol 2005; 202:32-40. [PMID: 15389551 DOI: 10.1002/jcp.20084] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Progesterone-induced oocyte maturation is thought to involve the inhibition of an oocyte adenylyl cyclase and reduction of intracellular cAMP. Our previous studies demonstrated that injection of inhibitors of G protein betagamma complex induces hormone-independent oocyte maturation. In contrast, over-expression of Xenopus Gbeta1 (xGbeta1), alone or together with bovine Ggamma2, elevates oocyte cAMP and inhibits progesterone-induced oocyte maturation. To further investigate the mechanism of Gbetagamma-induced oocyte maturation, we generated a mutant xGbeta1, substituting Asp-228 for Gly (D228G). An equivalent mutation in the mammalian Gbeta1 results in the loss of its ability to activate adenylyl cyclases. Indeed, co-injection of xGbeta1D228G with Ggamma2 failed to increase oocyte cAMP or inhibit progesterone-induced oocyte maturation. To directly demonstrate that oocytes contained a Gbetagamma-regulated adenylyl cyclase, we analyzed cAMP formation in vitro by using oocyte membrane preparations. Purified brain Gbetagamma complexes significantly activated membrane-bound adenylyl cyclase activities. Multiple adenylyl cyclase isoforms were identified in frog oocytes by PCR using degenerate primers corresponding to highly conserved catalytic amino acid sequences. Among these we identified a partial Xenopus adenylyl cyclase 7 (xAC7) that was 65% identical in amino acid sequence to human AC7. A dominant-negative mutant of xAC7 induced hormone-independent oocyte maturation and accelerated progesterone-induced oocyte maturation. Theses findings suggest that xAC7 is a major component of the G2 arrest mechanism in Xenopus oocytes.
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Affiliation(s)
- Yinglun Sheng
- Ottawa Health Research Institute, Ottawa Hospital, 1053 Carling Avenue, Ottawa, Canada
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37
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Abi-Gerges N, Philp K, Pollard C, Wakefield I, Hammond TG, Valentin JP. Sex differences in ventricular repolarization: from cardiac electrophysiology to Torsades de Pointes. Fundam Clin Pharmacol 2004; 18:139-51. [PMID: 15066127 DOI: 10.1111/j.1472-8206.2004.00230.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A number of non-cardiovascular drugs have been withdrawn from clinical use due to unacceptable adverse cardiac side-effects involving drug-induced Torsades de Pointes (TdP)--a rare, life-threatening polymorphic ventricular tachycardia associated with prolongation of the action potential duration of ventricular myocytes and, hence, prolongation of the QT interval, of the electrocardiogram (ECG), which measures the total time for activation of the ventricles and their recovery to the resting state. Research has suggested that women are more prone to develop TdP than men during administration of medicines that share the potential to prolong the QT interval, with 65-75% of drug-induced TdP occurring in women. Clinical and experimental studies show that female sex demonstrate differences in the electrocardiographic pattern of ventricular repolarization in human and other animal species and is associated with a longer rate-corrected QT (QTc) interval at baseline than males. Reports of a similar propensity towards drug-induced TdP in both premenopausal and postmenopausal women support factors in addition to those of female sex hormones eliciting sex-based differences in ventricular repolarization. However, conflicting evidence suggests sex hormones may have a role in increasing the susceptibility of women or ultimately reducing the susceptibility of men to TdP. Cyclical variations in hormone levels during the menstrual cycle have been associated with an increased and reduced risk of TdP. In contradiction to this finding, the male sex hormone is thought to be beneficial. Modulation of the ventricular repolarization by testosterone may explain why the QTc interval shortens at puberty, and might account for the tendency towards an age-dependent reduction in the incidence of drug-induced TdP in men. Mechanisms underlying these differences are not fully understood but a case for the involvement of gonadal steroids is obviously strong. Therefore, further non-clinical/clinical investigations ought to be a necessary step to elucidate any sex differences in cardiac repolarization characteristics, QT interval prolongation and susceptibility to cardiac arrhythmias. This may have implications for the development of the safest medicinal products and for the clinical management of cardiac arrhythmias.
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Affiliation(s)
- Najah Abi-Gerges
- Department of Safety Pharmacology, Safety Assessment UK, AstraZeneca R & D, Alderley Park, Macclesfield, Cheshire, SK10 4TG, UK
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Abstract
Several recent studies have suggested that resumption of oocyte meiosis, indicated by germinal vesicle breakdown or GVBD, involves inhibition of endogenous heterotrimeric G proteins in both frogs and mice. These studies imply that a heterotrimeric G protein(s), and hence its upstream activator (a G protein-coupled receptor or GpCR), is activated in prophase oocytes and is responsible for maintaining meiosis arrest. To test the existence and function of this putative GpCR, we utilized a mammalian G-protein-coupled receptor kinase (GRK3) and beta-arrestin-2, which together are known to cause GpCR desensitization. Injection of mRNA for rat GRK3 caused hormone-independent GVBD. The kinase activity of GRK3 was essential for GVBD induction as its kinase-dead mutant (GRK3-K220R) was completely ineffective. Another GRK3 mutant (GRK3-DeltaC), which lacked the C-terminal G(betagamma)-binding domain and which was not associated with oocyte membranes, also failed to induce GVBD. Furthermore, injection of rat beta-arrestin-2 mRNA also induced hormone-independent GVBD. Several inhibitors of clathrin-mediated receptor endocytosis (the clathrin-binding domain of beta-arrestin-2, concanavalin A, and monodansyl cadaverine) significantly reduced the abilities of GRK3/beta-arrestin-2 to induce GVBD. These results support the central role of a yet-unidentified GpCR in maintaining prophase arrest in frog oocytes and provide a potential means for its molecular identification.
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Affiliation(s)
- Jing Wang
- Ottawa Health Research Institute, Ottawa Hospital Civic Campus, 725 Parkdale Avenue, Ottawa, Ontario K1Y 4E9, Canada
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Booth RA, Cummings C, Tiberi M, Liu XJ. GIPC participates in G protein signaling downstream of insulin-like growth factor 1 receptor. J Biol Chem 2002; 277:6719-25. [PMID: 11751850 DOI: 10.1074/jbc.m108033200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Several recent studies have demonstrated that insulin-like growth factor (IGF)-1-induced mitogen-activated protein kinase (MAP kinase) activation is abolished by pertussis toxin, suggesting that trimeric G proteins of the G(i) class are novel cellular targets of the IGF-1 signaling pathway. We report here that the intracellular domain of the Xenopus IGF-1 receptor is capable of binding to the Xenopus homolog of mammalian GIPC, a PDZ domain-containing protein previously identified as a binding partner of G(i)-specific GAP (RGS-GAIP). Binding of xGIPC to xIGF-1 receptor is independent of the kinase activity of the receptor and appears to require the PDZ domain of xGIPC. Injection of two C-terminal truncation mutants that retained the PDZ domain blocked IGF-1-induced Xenopus MAP kinase activation and oocyte maturation. While full-length xGIPC injection did not significantly alter insulin response, it greatly enhanced human RGS-GAIP in stimulating the insulin response in frog oocytes. This represents the first demonstration that GIPC x RGS-GAIP complex acts positively in IGF-1 receptor signal transduction.
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Affiliation(s)
- Ronald A Booth
- Ottawa Health Research Institute, Ottawa Hospital, Ottawa K1Y 4E9, Canada
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Machaca K, Haun S. Induction of maturation-promoting factor during Xenopus oocyte maturation uncouples Ca(2+) store depletion from store-operated Ca(2+) entry. J Cell Biol 2002; 156:75-85. [PMID: 11781335 PMCID: PMC1307503 DOI: 10.1083/jcb.200110059] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2001] [Revised: 11/15/2001] [Accepted: 11/19/2001] [Indexed: 11/22/2022] Open
Abstract
During oocyte maturation, eggs acquire the ability to generate specialized Ca(2+) signals in response to sperm entry. Such Ca(2+) signals are crucial for egg activation and the initiation of embryonic development. We examined the regulation during Xenopus oocyte maturation of store-operated Ca(2+) entry (SOCE), an important Ca(2+) influx pathway in oocytes and other nonexcitable cells. We have previously shown that SOCE inactivates during Xenopus oocyte meiosis. SOCE inactivation may be important in preventing premature egg activation. In this study, we investigated the correlation between SOCE inactivation and the Mos-mitogen-activated protein kinase (MAPK)-maturation-promoting factor (MPF) kinase cascade, which drives Xenopus oocyte maturation. SOCE inactivation at germinal vesicle breakdown coincides with an increase in the levels of MAPK and MPF. By differentially inducing Mos, MAPK, and MPF, we demonstrate that the activation of MPF is necessary for SOCE inactivation during oocyte maturation. In contrast, sustained high levels of Mos kinase and the MAPK cascade have no effect on SOCE activation. We further show that preactivated SOCE is not inactivated by MPF, suggesting that MPF does not block Ca(2+) influx through SOCE channels, but rather inhibits coupling between store depletion and SOCE activation.
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Affiliation(s)
- Khaled Machaca
- Department of Physiology and Biophysics, University of Arkansas Medical Science, Little Rock, 72205, USA.
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Ledda S, Bogliolo L, Leoni G, Naitana S. Cell coupling and maturation-promoting factor activity in in vitro-matured prepubertal and adult sheep oocytes. Biol Reprod 2001; 65:247-52. [PMID: 11420246 DOI: 10.1095/biolreprod65.1.247] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
We examined some differences between prepubertal and adult ovine oocytes; in particular we analyzed the functional status of the cumulus-oocyte complex, protein synthesis during in vitro maturation, and because no information is available on prepubertal and adult sheep, maturation-promoting factor (MPF) fluctuations throughout meiotic progression both in prepubertal and adult sheep oocytes. After 24 h of maturation, percentages of MII oocytes were similar between prepubertal and adult animals. Electron microscopy examinations showed that prepubertal oocytes had fewer transzonal projections than adult oocytes. Methionine uptake was significantly lower in prepubertal cumulus-enclosed oocytes examined through meiotic progression. On the contrary, denuded prepubertal oocytes showed a higher methionine incorporation in the first 4 h of incubation compared with adult oocytes. We also found some differences in MPF activity between prepubertal and adult oocytes at MII stage. In fact, prepubertal MII oocytes had a significantly lower level of MPF activity than adult oocytes did and, after fusion with germinal vesicle oocytes, they were unable to induce nuclear breakdown and chromosome condensation 1-2 h post-fusion, whereas adult MII oocytes could induce these processes. Our findings show that the lesser competence of prepubertal oocytes could be due to morphological anomalies and alterations in physiological activity and that oocytes do not reach full developmental competence until puberty.
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Affiliation(s)
- S Ledda
- Department of Animal Biology, University of Sassari, 07100 Sassari, Italy.
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42
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Sadler SE. Low-density caveolae-like membrane from Xenopus laevis oocytes is enriched in Ras. J Cell Biochem 2001; 83:21-32. [PMID: 11500951 DOI: 10.1002/jcb.1207] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Detergent-free discontinuous sucrose density gradient centrifugation was used to resolve low- and high-density membrane fractions from Xenopus laevis oocytes. Compared to high-density membrane, low-density oocyte membrane is enriched two-fold in cholesterol and highly enriched in ganglioside GM1. Protein immunoblotting of membrane fractions from whole cells with polyclonal anti-human caveolin antibody detected multiple bands, including a distinctive triad with apparent molecular weights of 21, 33, and 48 kDa. To more clearly determine which of these caveolin-like protein(s) is associated with the oocyte plasma membrane, microdissection was used to separate external membrane (cortical preparations containing plasma membrane) from intracellular membrane. Cortical membrane preparations displayed a single 21-kDa caveolin-like protein in low-density membrane. Internal oocyte membrane displayed the higher molecular weight bands of 33 and 48 kDa and a lesser amount of the 21-kDa protein in low-density membrane fractions. Monoclonal anti-human Ras antibody detected a single 23-kDa immunoblot band that is enriched an average of eight-fold in low-density membrane fractions prepared from whole cells. This is the first report of caveolin-associated, low-density membrane in amphibian oocytes, and is consistent with a role for caveolin and caveolae-like microdomains in oocyte signal transduction.
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Affiliation(s)
- S E Sadler
- Department of Biological Sciences, University of Denver, University Park, Denver, CO 80208, USA.
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43
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Shuba YM, Degtiar VE, Osipenko VN, Naidenov VG, Woosley RL. Testosterone-mediated modulation of HERG blockade by proarrhythmic agents. Biochem Pharmacol 2001; 62:41-9. [PMID: 11377395 DOI: 10.1016/s0006-2952(01)00611-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Diverse drugs from many therapeutic classes exert cardiotoxic side effects by inducing torsades de pointes (TdP), a life threatening cardiac arrhythmia, which often results from drug interaction with HERG (human ether-a-go-go related gene) encoded K(+) channels, that generate an I(Kr) component of the delayed rectifier cardiac K(+) current. Men are known to be at a lower risk for drug-induced TdP than women suggesting a role of sex steroid hormones, androgens and estrogens, in modulation of drug sensitivity of cardiac K(+) channels, particularly those encoded by HERG. Here by using neuroleptic agents haloperidol, pimozide, and fluspirilene, all of which can induce TdP, and a steroid hormone-sensitive system Xenopus oocytes for HERG channels expression we show that testosterone is able to reduce HERG-blocking potency of neuroleptics. Haloperidol, pimozide, and fluspirilene inhibited HERG current with IC(50) of 1.36, 1.74, and 2.34 microM, and maximal block of 73%, 76% and 65%, respectively. The action of these neuroleptics was voltage-dependent, most consistent with an open-channel blocking mechanism. Pretreatment of HERG-expressing oocytes with 1 microM testosterone increased the IC(50) values to 2.73, 2.08, and 5.04 microM, reduced the maximal block to 65%, 59%, and 64%, and strongly diminished voltage-dependence of the blockade. Testosterone treatment per se produced about a 35% reduction of HERG current compared with untreated oocytes. Our data suggest that androgens may protect against the arrhythmogenic actions of some cardiotoxic drugs.
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Affiliation(s)
- Y M Shuba
- Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Bogomoletz St., 4, Kyiv-24, Ukraine.
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44
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Sheng Y, Tiberi M, Booth RA, Ma C, Liu XJ. Regulation of Xenopus oocyte meiosis arrest by G protein betagamma subunits. Curr Biol 2001; 11:405-16. [PMID: 11301251 DOI: 10.1016/s0960-9822(01)00123-3] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Progesterone induces the resumption of meiosis (maturation) in Xenopus oocytes through a nongenomic mechanism involving inhibition of an oocyte adenylyl cyclase and reduction of intracellular cAMP. However, progesterone action in Xenopus oocytes is not blocked by pertussis toxin, and this finding indicates that the inhibition of the oocyte adenylyl cyclase is not mediated by the alpha subunits of classical G(i)-type G proteins. RESULTS To investigate the possibility that G protein betagamma subunits, rather than alpha subunits, play a key role in regulating oocyte maturation, we have employed two structurally distinct G protein betagamma scavengers (G(t)alpha and betaARK-C(CAAX)) to sequester free Gbetagamma dimers. We demonstrated that the injection of mRNA encoding either of these Gbetagamma scavengers induced oocyte maturation. The Gbetagamma scavengers bound an endogenous, membrane-associated Gbeta subunit, indistinguishable from Xenopus Gbeta1 derived from mRNA injection. The injection of Xenopus Gbeta1 mRNA, together with bovine Ggamma2 mRNA, elevated oocyte cAMP levels and inhibited progesterone-induced oocyte maturation. CONCLUSION An endogenous G protein betagamma dimer, likely including Xenopus Gbeta1, is responsible for maintaining oocyte meiosis arrest. Resumption of meiosis is induced by Gbetagamma scavengers in vitro or, naturally, by progesterone via a mechanism that suppresses the release of Gbetagamma.
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Affiliation(s)
- Y Sheng
- Loeb Research Institute, Ottawa Hospital, K1Y 4E9, Ottawa, Canada
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45
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Shcherbatko AD, Davenport CM, Speh JC, Levinson SR, Mandel G, Brehm P. Progesterone treatment abolishes exogenously expressed ionic currents in Xenopus oocytes. Am J Physiol Cell Physiol 2001; 280:C677-88. [PMID: 11171587 DOI: 10.1152/ajpcell.2001.280.3.c677] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fully grown oocytes of Xenopus laevis undergo resumption of the meiotic cycle when treated with the steroid hormone progesterone. Previous studies have shown that meiotic maturation results in profound downregulation of specific endogenous membrane proteins in oocytes. To determine whether the maturation impacts the functional properties of exogenously expressed membrane proteins, we used cut-open recordings from Xenopus oocytes expressing several types of Na(+) and K(+) channels. Treatment of oocytes with progesterone resulted in a downregulation of heterologously expressed Na(+) and K(+) channels without a change in the kinetics of the currents. The time course of progesterone-induced ion channel inhibition was concentration dependent. Complete elimination of Na(+) currents temporally coincided with development of germinal vesicle breakdown, while elimination of K(+) currents was delayed by approximately 2 h. Coexpression of human beta(1)-subunit with rat skeletal muscle alpha-subunit in Xenopus oocytes did not prevent progesterone-induced downregulation of Na(+) channels. Addition of 8-bromo-cAMP to oocytes or injection of heparin before progesterone treatment prevented the loss of expressed currents. Pharmacological studies suggest that the inhibitory effects of progesterone on expressed Na(+) and K(+) channels occur downstream of the activation of cdc2 kinase. The loss of channels is correlated with a reduction in Na(+) channel immunofluorescence, pointing to a disappearance of the ion channel-forming proteins from the surface membrane.
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Affiliation(s)
- A D Shcherbatko
- Department of Neurobiology and Behavior, State University of New York at Stony Brook, Stony Brook, New York 11794, USA.
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46
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Machaca K, Haun S. Store-operated calcium entry inactivates at the germinal vesicle breakdown stage of Xenopus meiosis. J Biol Chem 2000; 275:38710-5. [PMID: 10991950 PMCID: PMC1201341 DOI: 10.1074/jbc.m007887200] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Store-operated calcium entry (SOCE) is the predominant Ca(2+) influx pathway in non-excitable cells and is activated in response to depletion of intracellular Ca(2+) stores. We have studied SOCE regulation during Xenopus oocyte meiosis. SOCE can be measured readily in stage VI Xenopus oocytes arrested at the G(2)-M transition of the cell cycle, either by Ca(2+) imaging or by recording the SOCE current. However, following meiotic maturation, SOCE can no longer be activated by store depletion. We have characterized the time course of SOCE inactivation during oocyte maturation, and show that SOCE inactivates almost completely, in a very short time period, at the germinal vesicle breakdown stage of meiosis. This acute inactivation offers an opportunity to better understand SOCE regulation.
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Affiliation(s)
- K Machaca
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
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47
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Bayaa M, Booth RA, Sheng Y, Liu XJ. The classical progesterone receptor mediates Xenopus oocyte maturation through a nongenomic mechanism. Proc Natl Acad Sci U S A 2000; 97:12607-12. [PMID: 11050156 PMCID: PMC18811 DOI: 10.1073/pnas.220302597] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Xenopus laevis oocytes are physiologically arrested at G(2) of meiosis I. Resumption of meiosis, or oocyte maturation, is triggered by progesterone. Progesterone-induced Xenopus oocyte maturation is mediated via an extranuclear receptor and is independent of gene transcription. The identity of this extranuclear oocyte progesterone receptor (PR), however, has remained a longstanding problem. We have isolated the amphibian homologue of human PR from a Xenopus oocyte cDNA library. The cloned Xenopus progesterone receptor (xPR) functioned in heterologous cells as a progesterone-regulated transcription activator. However, endogenous xPR was excluded from the oocyte nucleus and instead appeared to be a cytosolic protein not associated with any membrane structures. Injection of xPR mRNA into Xenopus oocytes accelerated the progesterone-induced oocyte maturation and reduced the required concentrations of progesterone. In enucleated oocytes, xPR accelerated the progesterone-induced mitogen-activated protein kinase activation. These data suggest that xPR is the long sought after Xenopus oocyte receptor responsible for progesterone-induced oocyte maturation.
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Affiliation(s)
- M Bayaa
- Loeb Research Institute, Ottawa Hospital, 1053 Carling Avenue, Ottawa, ON, Canada
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48
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Yamashita M, Mita K, Yoshida N, Kondo T. Molecular mechanisms of the initiation of oocyte maturation: general and species-specific aspects. PROGRESS IN CELL CYCLE RESEARCH 2000; 4:115-29. [PMID: 10740820 DOI: 10.1007/978-1-4615-4253-7_11] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Stimulated by maturation-inducing hormone secreted from follicle cells surrounding the oocytes, fully-grown oocytes mature and become fertilisable. During maturation, immature oocytes resume meiosis arrested at the first prophase and proceed to the first or second metaphase at which they are naturally inseminated. Paying special attention to general and species-specific aspects, we summarise the mechanisms regulating the initial phase of oocyte maturation, from the reception of hormonal signals on the oocyte surface to activation of the maturation-promoting factor in the cytoplasm, in amphibians, fishes, mammals and marine invertebrates.
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Affiliation(s)
- M Yamashita
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
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49
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Yoshida N, Mita K, Yamashita M. Comparative study of the molecular mechanisms of oocyte maturation in amphibians. Comp Biochem Physiol B Biochem Mol Biol 2000; 126:189-97. [PMID: 10874166 DOI: 10.1016/s0305-0491(00)00197-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Maturation-promoting factor (MPF), a complex of Cdc2 and cyclin B, is the final inducer of oocyte maturation. Its activity is controlled by inhibitory phosphorylation of Cdc2 on Tyr15/Thr14 and activating phosphorylation on Thr161. Full-grown immature oocytes of the African clawed frog Xenopus laevis contain inactive MPF (pre-MPF) that comprises cyclin B-bound Cdc2 phosphorylated on Tyr15/Thr14 and Thr161. The synthesis of Mos, but not cyclin B, after stimulation by the maturation-inducing steroid progesterone, is believed to be necessary for initiating Xenopus oocyte maturation through Tyr15/Thr14 dephosphorylation of pre-MPF. In contrast, amphibians other than Xenopus (and also fishes) employ a different mechanism. Full-grown immature oocytes of these species contain monomeric Cdc2 but not cyclin B. MPF is formed after hormonal stimulation by binding of the newly produced cyclin B to the pre-existing Cdc2 and is immediately activated through Thr161 phosphorylation. Mos/MAP kinase is neither necessary nor sufficient for initiating maturation in fishes and amphibians except for Xenopus. We propose a new model of MPF formation and activation during oocyte maturation that is applicable to all amphibians (as well as fishes), based on a novel concept that pre-MPF is an artificial molecule that is not essential for inducing oocyte maturation.
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Affiliation(s)
- N Yoshida
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, Japan
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50
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Abstract
Epidermal growth factor (EGF) has received much attention recently for its positive effects on mammalian oocyte maturation and embryo development and its potential importance in cytoplasmic maturation of oocytes. Calcium (Ca2+) homeostasis in germinal vesicle stage oocytes has also been suggested to play a role in cytoplasmic maturation. This study examined the effects of EGF on Ca2+ mobilization as measured by its efflux from mouse oocytes at three time periods throughout maturation (0-4 hr, 4-8 hr, and 12 hr). Immature cumulus oocyte complexes (COCs) removed from the ovary for less than 4 hr exhibit oscillations in Ca2+ efflux that initiated 5-30 min following EGF stimulation. This response was not observed in COCs matured for 4-8 hr or 12 hr or in unstimulated 0-4 hr COCs. Denuded oocytes and cumulus cells did not show the same response to EGF (8.2 nM and 16.4 nM). Immunohistochemistry for detection of the EGF receptor along with EGF internalization studies showed that receptors are present both on cumulus cells and the oocyte but EGF appears to be internalized mainly by the cumulus cells. These data demonstrate that EGF induces oscillations in Ca2+ efflux in COCs 0-4 hr old and this response is mediated by the cumulus cells.
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Affiliation(s)
- J L Hill
- Department of Biochemistry and Molecular Biology, Lederle Graduate Research Center, University of Massachusetts, Amherst 01003, USA
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