1
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Quiñones-Frías MC, Ocken DM, Rodal A. High-resolution imaging of presynaptic ER networks in Atlastin mutants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.01.555994. [PMID: 37693578 PMCID: PMC10491308 DOI: 10.1101/2023.09.01.555994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The endoplasmic reticulum (ER) is a continuous organelle that extends to the periphery of neurons and regulates many neuronal functions including neurite outgrowth, neurotransmission, and synaptic plasticity. Mutations in proteins that control ER shape are linked to the neurodegenerative disorder Hereditary Spastic Paraplegia (HSP). However, the ultrastructure and dynamics of the neuronal ER have been under-investigated, particularly at presynaptic terminals. Here we developed new super-resolution and live imaging methods in D. melanogaster larval motor neurons to investigate ER structure at presynaptic terminals from wild-type animals, and in null mutants of the HSP gene Atlastin. Previous studies indicated diffuse localization of an ER lumen marker at Atlastin mutant presynaptic terminals, which was attributed to ER fragmentation. By contrast, we found using an ER membrane marker that the ER in Atlastin mutants formed robust networks. Further, our high-resolution imaging results suggest that overexpression of luminal ER proteins in Atlastin mutants causes their progressive displacement to the cytosol at synapses, perhaps due to proteostatic stress and/or changes in ER membrane integrity. Remarkably, these luminal ER proteins remain correctly localized in cell bodies, axons, and other cell types such as body wall muscles, suggesting that ER tubules at synapses have unique structural and functional characteristics. This displacement phenotype has not been reported in numerous studies of Atlastin in non-neuronal cells, emphasizing the importance of conducting experiments in neurons when investigating the mechanisms leading to upper motor neuron dysfunction in HSP.
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Affiliation(s)
| | - Dina M. Ocken
- Department of Biology, Brandeis University, Waltham, MA
| | - Avital Rodal
- Department of Biology, Brandeis University, Waltham, MA
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2
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Xing F, Qu S, Liu J, Yang J, Hu F, Drevenšek-Olenik I, Pan L, Xu J. Intercellular Bridge Mediates Ca 2+ Signals between Micropatterned Cells via IP 3 and Ca 2+ Diffusion. Biophys J 2020; 118:1196-1204. [PMID: 32023438 DOI: 10.1016/j.bpj.2020.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 12/06/2019] [Accepted: 01/06/2020] [Indexed: 12/12/2022] Open
Abstract
Intercellular bridges are plasma continuities formed at the end of the cytokinesis process that facilitate intercellular mass transport between the two daughter cells. However, it remains largely unknown how the intercellular bridge mediates Ca2+ communication between postmitotic cells. In this work, we utilize BV-2 microglial cells planted on dumbbell-shaped micropatterned assemblies to resolve spatiotemporal characteristics of Ca2+ signal transfer over the intercellular bridges. With the use of such micropatterns, considerably longer and more regular intercellular bridges can be obtained than in conventional cell cultures. The initial Ca2+ signal is evoked by mechanical stimulation of one of the daughter cells. A considerable time delay is observed between the arrivals of passive Ca2+ diffusion and endogenous Ca2+ response in the intercellular-bridge-connected cell, indicating two different pathways of the Ca2+ communication. Extracellular Ca2+ and the paracrine pathway have practically no effect on the endogenous Ca2+ response, demonstrated by application of Ca2+-free medium, exogenous ATP, and P2Y13 receptor antagonist. In contrast, the endoplasmic reticulum Ca2+-ATPase inhibitor thapsigargin and inositol trisphosphate (IP3) receptor blocker 2-aminoethyl diphenylborate significantly inhibit the endogenous Ca2+ increase, which signifies involvement of IP3-sensitive calcium store release. Notably, passive Ca2+ diffusion into the connected cell can clearly be detected when IP3-sensitive calcium store release is abolished by 2-aminoethyl diphenylborate. Those observations prove that both passive Ca2+ diffusion and IP3-mediated endogenous Ca2+ response contribute to the Ca2+ increase in intercellular-bridge-connected cells. Moreover, a simulation model agreed well with the experimental observations.
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Affiliation(s)
- Fulin Xing
- The Key Laboratory of Weak-Light Nonlinear Photonics of Education Ministry, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin, China
| | - Songyue Qu
- The Key Laboratory of Weak-Light Nonlinear Photonics of Education Ministry, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin, China
| | - Junfang Liu
- The Key Laboratory of Weak-Light Nonlinear Photonics of Education Ministry, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin, China
| | - Jianyu Yang
- The Key Laboratory of Weak-Light Nonlinear Photonics of Education Ministry, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin, China
| | - Fen Hu
- The Key Laboratory of Weak-Light Nonlinear Photonics of Education Ministry, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin, China
| | - Irena Drevenšek-Olenik
- Faculty of Mathematics and Physics, University of Ljubljana, and J. Stefan Institute, Ljubljana, Slovenia
| | - Leiting Pan
- The Key Laboratory of Weak-Light Nonlinear Photonics of Education Ministry, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin, China.
| | - Jingjun Xu
- The Key Laboratory of Weak-Light Nonlinear Photonics of Education Ministry, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin, China; Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi, China
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3
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Piegari E, Villarruel C, Ponce Dawson S. Changes in Ca 2+ Removal Can Mask the Effects of Geometry During IP 3R Mediated Ca 2+ Signals. Front Physiol 2019; 10:964. [PMID: 31417423 PMCID: PMC6684793 DOI: 10.3389/fphys.2019.00964] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 07/11/2019] [Indexed: 12/29/2022] Open
Abstract
Calcium (Ca2+) signals are ubiquitous. Most intracellular Ca2+ signals involve the release of Ca2+ from the endoplasmic reticulum (ER) through Inositol 1,4,5-Trisphosphate Receptors (IP3Rs). The non-uniform spatial organization of IP3Rs and the fact that their individual openings are coupled via cytosolic Ca2+ are key factors for the variety of spatio-temporal distributions of the cytosolic [Ca2+] and the versatility of the signals. In this paper we combine experiments performed in untreated and in progesterone-treated Xenopus laevis oocytes and mathematical models to investigate how the interplay between geometry (the IP3R spatial distribution) and dynamics (the processes that characterize the release, transport, and removal of cytosolic Ca2+) affects the resulting signals. Signal propagation looks more continuous and spatially uniform in treated (mature) than in untreated (immature) oocytes. This could be due to the different underlying IP3R spatial distribution that has been observed in both cell types. The models, however, show that the rate of cytosolic Ca2+ removal, which is also different in both cell types, plays a key role affecting the coupling between Ca2+ release sites in such a way that the effect of the underlying IP3R spatial distribution can be modified.
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Affiliation(s)
- Estefanía Piegari
- Departamento de Física FCEN-UBA and IFIBA (CONICET), Ciudad Universitaria, Buenos Aires, Argentina
| | - Cecilia Villarruel
- Departamento de Física FCEN-UBA and IFIBA (CONICET), Ciudad Universitaria, Buenos Aires, Argentina
| | - Silvina Ponce Dawson
- Departamento de Física FCEN-UBA and IFIBA (CONICET), Ciudad Universitaria, Buenos Aires, Argentina
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4
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Taylor CW, Machaca K. IP3 receptors and store-operated Ca2+ entry: a license to fill. Curr Opin Cell Biol 2019; 57:1-7. [DOI: 10.1016/j.ceb.2018.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 10/05/2018] [Indexed: 10/28/2022]
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5
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Fees CP, Stith BJ. Insemination or phosphatidic acid induces an outwardly spiraling disk of elevated Ca 2+ to produce the Ca 2+ wave during Xenopus laevis fertilization. Dev Biol 2019; 448:59-68. [PMID: 30641042 DOI: 10.1016/j.ydbio.2019.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 01/03/2019] [Accepted: 01/04/2019] [Indexed: 02/06/2023]
Abstract
During Xenopus fertilization, the initial intracellular calcium ((Ca2+)i) release at the sperm-egg binding site (hot spot) has not been described without the use of inhibitors, nor related to underlying ER structure. Without inhibitors, we now report that sperm induce an initial hot spot after sperm addition to Xenopus eggs that was ~25 µm. This area is consistent with the size of ER patches and clusters of IP3 receptors that have enhanced activity. Furthermore, we find a new mechanism for the fertilization (Ca2+)i wave; instead of outward diffusion of inositol 1,4,5-trisphosphate (IP3), we find that the wave was generated by an outward, clockwise rotation of a ~63 µm disk of elevated (Ca2+)i moving very rapidly at ~65 µm/s. We also suggest a new mechanism for the acceleration of the fertilization (Ca2+)i wave as the disk accelerated and was joined by other rotating disks (some rotating counterclockwise) at a time when the speed of the (Ca2+)i wave increases. To examine the role of phosphatidic acid (PA) in the release of (Ca2+)i during Xenopus fertilization, we find that two inhibitors of PA production delayed the appearance of fertilization hot spots by ~9-12 min but did not reduce the size of hot spots and actually accelerated the later (Ca2+)i wave. Surprisingly, global addition of PA to Xenopus eggs induced localized hot spots at a time and size that was similar to those induced after sperm addition. In contrast, sperm induce a rapid (Ca2+)i wave (~4 µm/s) within ~30 s after hot spot appearance, whereas hot spots induced by PA required an ~32 min to induce a very slow (~1 µm/s) (Ca2+)i wave with a lower peak of (Ca2+)i. Thus, PA may not be required for the initial release of (Ca2+)i at the sperm-egg binding site, but mimics sperm by inducing a similarly sized localized (Ca2+)i release. As compared with sperm, PA may induce a weak, slow (Ca2+)i wave by slowly increasing IP3 receptor clustering. Addition of PA to Xenopus oocytes, or Ca2+ ionophore to either Xenopus oocytes or eggs, did not induce hot spots but a global (Ca2+)i wave that rapidly moved at ~12 µm/s.
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6
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Yoon SY. Role of Type 1 Inositol 1,4,5-triphosphate Receptors in Mammalian Oocytes. Dev Reprod 2019; 23:1-9. [PMID: 31049467 PMCID: PMC6487317 DOI: 10.12717/dr.2019.23.1.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/17/2019] [Accepted: 02/27/2019] [Indexed: 11/17/2022]
Abstract
The ability of oocytes to undergo normal fertilization and embryo development is
acquired during oocyte maturation which is transition from the germinal vesicle
stage (GV), germinal vesicle breakdown (GVBD) to metaphase of meiosis II (MII).
Part of this process includes redistribution of inositol 1,4, 5-triphosphate
receptor (IP3R), a predominant Ca2+ channel on the endoplasmic
reticulum membrane. Type 1 IP3R (IP3R1) is expressed in mouse oocytes
dominantly. At GV stage, IP3R1 are arranged as a network throughout the
cytoplasm with minute accumulation around the nucleus. At MII stage, IP3R1
diffuses to the entire cytoplasm in a more reticular manner, and obvious
clusters of IP3R1 are observed at the cortex of the egg. This structural
reorganization provides acquisition of [Ca2+]i oscillatory
activity during fertilization. In this review, general properties of IP3R1 in
somatic cells and mammalian oocyte are introduced.
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Affiliation(s)
- Sook Young Yoon
- Fertility Center of CHA Gangnam Medical Center, CHA University, Seoul 06125, Korea
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7
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Reconstitution of Intracellular Calcium Signaling in Xenopus Egg Extracts. Methods Mol Biol 2019. [PMID: 30737685 DOI: 10.1007/978-1-4939-9009-2_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Generation of calcium signal in the cytoplasm of fertilized or parthenogenetically activated eggs has been extensively studied in the intact eggs of several biological species. Calcium transient was found to elicit a plethora of biochemical and cellular events in these cells. Remarkably, intracellular calcium signaling can also be reconstituted in cell-free environment. In this chapter, we describe the methods that allow reconstitution, detection, and quantification of the calcium signal in cell-free extracts of Xenopus oocytes and eggs.
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8
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Maturation and fertilization of echinoderm eggs: Role of actin cytoskeleton dynamics. Biochem Biophys Res Commun 2018; 506:361-371. [DOI: 10.1016/j.bbrc.2018.09.084] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 09/13/2018] [Indexed: 01/31/2023]
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9
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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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10
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Zhang N, Yoon SY, Parys JB, Fissore RA. Effect of M-phase kinase phosphorylations on type 1 inositol 1,4,5-trisphosphate receptor-mediated Ca2+ responses in mouse eggs. Cell Calcium 2015; 58:476-88. [PMID: 26259730 DOI: 10.1016/j.ceca.2015.07.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 12/26/2022]
Abstract
The type 1 inositol 1,4,5-trisphosphate receptor (IP3R1) mediates increases in the intracellular concentration of Ca(2+) ([Ca(2+)]i) during fertilization in mammalian eggs. The activity of IP3R1 is enhanced during oocyte maturation, and phosphorylations by M-phase kinases are thought to positively regulate the activity of IP3R1. Accordingly, we and others have found that IP3R1 is phosphorylated at S(421), T(799) (by Cdk1) and at S(436) (by ERK). Nevertheless, the effects of these phosphorylations on the function of the receptor and their impact on [Ca(2+)]i oscillations in eggs have not been clearly examined. To address this, we expressed in mouse oocytes an IP3R1 variant with the three indicated phosphorylation sites replaced by acidic residues, IIIE-IP3R1, such that it would act like a constitutively phosphorylated IP3R1, and examined [Ca(2+)]i parameters in response to stimuli. We found that overexpression of wild type (wt-IP3R1) or IIIE-IP3R1 in oocytes containing endogenous receptors caused dominant negative-like effects on Ca(2+) release and oscillations. Therefore, we first selectively removed the endogenous IP3R1, and subsequently expressed the exogenous receptors. We found that in response to injection of PLCζ cRNA, eggs without endogenous IP3R1 failed to mount persistent Ca(2+) oscillations, although expression of wt-IP3R1 restored their [Ca(2+)]i oscillatory activity. We also observed that the Ca(2+) oscillatory ability and the sensitivity to IP3 in eggs expressing IIIE-IP3R1 were greater than in those expressing wt-IP3R1. Lastly, we found that exogenous IP3R1s are resistant to downregulation and support longer oscillations and of higher amplitude. Altogether, our results show that phosphorylations by Cdk1 and MAPK enhance the activity of IP3R1, which is consistent with its maximal activity observed at the time of fertilization and the role of Ca(2+) release in egg activation.
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Affiliation(s)
- Nan Zhang
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA; Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Sook Young Yoon
- Fertility Center of CHA Gangnam Medical Center, College of Medicine, CHA University, Seoul 135-081, Republic of Korea
| | - Jan B Parys
- KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, Campus Gasthuisberg O/N-I box 802, Herestraat 49, BE-3000 Leuven, Belgium
| | - Rafael A Fissore
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, MA 01003, USA.
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11
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The role of IP3 receptor channel clustering in Ca2+ wave propagation during oocyte maturation. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015. [PMID: 24560141 DOI: 10.1016/b978-0-12-397897-4.00006-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
During oocyte maturation, the calcium-signaling machinery undergoes a dramatic remodeling resulting in distinctly different calcium-release patterns on all organizational scales from puffs to waves. The dynamics of the Ca(2+) release wave in mature as compared to immature oocytes are defined by a slower propagation speed and longer duration of the high Ca(2+) plateau. In this chapter, we use computational modeling to identify the changes in the signaling machinery, which contribute most significantly to the alterations observed in Ca(2+) wave propagation during Xenopus oocyte maturation. In addition to loss of store-operated calcium entry and internalization of plasma membrane pumps, we propose that spatial reorganization of the IP3 receptors in the plane of the ER membrane is a key factor for the observed signaling changes in Ca(2+) wave propagation.
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12
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Stith BJ. Phospholipase C and D regulation of Src, calcium release and membrane fusion during Xenopus laevis development. Dev Biol 2015; 401:188-205. [PMID: 25748412 DOI: 10.1016/j.ydbio.2015.02.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 02/15/2015] [Accepted: 02/24/2015] [Indexed: 11/28/2022]
Abstract
This review emphasizes how lipids regulate membrane fusion and the proteins involved in three developmental stages: oocyte maturation to the fertilizable egg, fertilization and during first cleavage. Decades of work show that phosphatidic acid (PA) releases intracellular calcium, and recent work shows that the lipid can activate Src tyrosine kinase or phospholipase C during Xenopus fertilization. Numerous reports are summarized to show three levels of increase in lipid second messengers inositol 1,4,5-trisphosphate and sn 1,2-diacylglycerol (DAG) during the three different developmental stages. In addition, possible roles for PA, ceramide, lysophosphatidylcholine, plasmalogens, phosphatidylinositol 4-phosphate, phosphatidylinositol 5-phosphate, phosphatidylinositol 4,5-bisphosphate, membrane microdomains (rafts) and phosphatidylinositol 3,4,5-trisphosphate in regulation of membrane fusion (acrosome reaction, sperm-egg fusion, cortical granule exocytosis), inositol 1,4,5-trisphosphate receptors, and calcium release are discussed. The role of six lipases involved in generating putative lipid second messengers during fertilization is also discussed: phospholipase D, autotaxin, lipin1, sphingomyelinase, phospholipase C, and phospholipase A2. More specifically, proteins involved in developmental events and their regulation through lipid binding to SH3, SH4, PH, PX, or C2 protein domains is emphasized. New models are presented for PA activation of Src (through SH3, SH4 and a unique domain), that this may be why the SH2 domain of PLCγ is not required for Xenopus fertilization, PA activation of phospholipase C, a role for PA during the calcium wave after fertilization, and that calcium/calmodulin may be responsible for the loss of Src from rafts after fertilization. Also discussed is that the large DAG increase during fertilization derives from phospholipase D production of PA and lipin dephosphorylation to DAG.
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Affiliation(s)
- Bradley J Stith
- University of Colorado Denver, Department of Integrative Biology, Campus Box 171, PO Box 173364, Denver, CO 80217-3364, United States.
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13
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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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14
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Calcium signaling and meiotic exit at fertilization in Xenopus egg. Int J Mol Sci 2014; 15:18659-76. [PMID: 25322156 PMCID: PMC4227238 DOI: 10.3390/ijms151018659] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/01/2014] [Accepted: 10/09/2014] [Indexed: 11/16/2022] Open
Abstract
Calcium is a universal messenger that mediates egg activation at fertilization in all sexually reproducing species studied. However, signaling pathways leading to calcium generation and the mechanisms of calcium-induced exit from meiotic arrest vary substantially among species. Here, we review the pathways of calcium signaling and the mechanisms of meiotic exit at fertilization in the eggs of the established developmental model, African clawed frog, Xenopus laevis. We also discuss calcium involvement in the early fertilization-induced events in Xenopus egg, such as membrane depolarization, the increase in intracellular pH, cortical granule exocytosis, cortical contraction, contraction wave, cortical rotation, reformation of the nuclear envelope, sperm chromatin decondensation and sister chromatid segregation.
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15
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Schwarz DS, Blower MD. The calcium-dependent ribonuclease XendoU promotes ER network formation through local RNA degradation. ACTA ACUST UNITED AC 2014; 207:41-57. [PMID: 25287301 PMCID: PMC4195833 DOI: 10.1083/jcb.201406037] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In both Xenopus laevis egg extract and human cells, an increase in cytosolic calcium activates the endogenous ribonuclease XendoU/hEndoU, which localizes to the ER, promotes RNA cleavage and RNP removal, and induces ER network assembly. How cells shape and remodel organelles in response to cellular signals is a poorly understood process. Using Xenopus laevis egg extract, we found that increases in cytosolic calcium lead to the activation of an endogenous ribonuclease, XendoU. A fraction of XendoU localizes to the endoplasmic reticulum (ER) and is required for nuclear envelope assembly and ER network formation in a catalysis-dependent manner. Using a purified vesicle fusion assay, we show that XendoU functions on the surface of ER membranes to promote RNA cleavage and ribonucleoprotein (RNP) removal. Additionally, RNA removal from the surface of vesicles by RNase treatment leads to increased ER network formation. Using human tissue culture cells, we found that hEndoU localizes to the ER, where it promotes the formation of ER tubules in a catalysis-dependent manner. Together, these results demonstrate that calcium-activated removal of RNA from membranes by XendoU promotes and refines ER remodeling and the formation of tubular ER.
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Affiliation(s)
- Dianne S Schwarz
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 Department of Genetics, Harvard Medical School, Boston, MA 02115
| | - Michael D Blower
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 Department of Genetics, Harvard Medical School, Boston, MA 02115
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16
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Mid-range Ca2+ signalling mediated by functional coupling between store-operated Ca2+ entry and IP3-dependent Ca2+ release. Nat Commun 2014; 5:3916. [PMID: 24867608 DOI: 10.1038/ncomms4916] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 04/17/2014] [Indexed: 11/08/2022] Open
Abstract
The versatility and universality of Ca(2+) signals stem from the breadth of their spatial and temporal dynamics. Spatially, Ca(2+) signalling is well studied in the microdomain scale, close to a Ca(2+) channel, and at the whole-cell level. However, little is known about how local Ca(2+) signals are regulated to specifically activate spatially distant effectors without a global Ca(2+) rise. Here we show that an intricate coupling between the inositol 1,4,5 trisphosphate (IP3) receptor, SERCA pump and store-operated Ca(2+) entry (SOCE) allows for efficient mid-range Ca(2+) signalling. Ca(2+) flowing through SOCE is taken up into the ER lumen by the SERCA pump, only to be re-released by IP3Rs to activate distal Ca(2+)-activated Cl(-) channels (CaCCs). This CaCC regulation contributes to setting the membrane potential of the cell. Hence functional coupling between SOCE, SERCA and IP3R limits local Ca(2+) diffusion and funnels Ca(2+) through the ER lumen to activate a spatially separate Ca(2+) effector.
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Kashir J, Deguchi R, Jones C, Coward K, Stricker SA. Comparative biology of sperm factors and fertilization-induced calcium signals across the animal kingdom. Mol Reprod Dev 2013; 80:787-815. [PMID: 23900730 DOI: 10.1002/mrd.22222] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/23/2013] [Indexed: 11/08/2022]
Abstract
Fertilization causes mature oocytes or eggs to increase their concentrations of intracellular calcium ions (Ca²⁺) in all animals that have been examined, and such Ca²⁺ elevations, in turn, provide key activating signals that are required for non-parthenogenetic development. Several lines of evidence indicate that the Ca²⁺ transients produced during fertilization in mammals and other taxa are triggered by soluble factors that sperm deliver into oocytes after gamete fusion. Thus, for a broad-based analysis of Ca²⁺ dynamics during fertilization in animals, this article begins by summarizing data on soluble sperm factors in non-mammalian species, and subsequently reviews various topics related to a sperm-specific phospholipase C, called PLCζ, which is believed to be the predominant activator of mammalian oocytes. After characterizing initiation processes that involve sperm factors or alternative triggering mechanisms, the spatiotemporal patterns of Ca²⁺ signals in fertilized oocytes or eggs are compared in a taxon-by-taxon manner, and broadly classified as either a single major transient or a series of repetitive oscillations. Both solitary and oscillatory types of fertilization-induced Ca²⁺ signals are typically propagated as global waves that depend on Ca²⁺ release from the endoplasmic reticulum in response to increased concentrations of inositol 1,4,5-trisphosphate (IP₃). Thus, for taxa where relevant data are available, upstream pathways that elevate intraoocytic IP3 levels during fertilization are described, while other less-common modes of producing Ca²⁺ transients are also examined. In addition, the importance of fertilization-induced Ca²⁺ signals for activating development is underscored by noting some major downstream effects of these signals in various animals.
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Affiliation(s)
- Junaid Kashir
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Headington, Oxford, UK
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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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Kinsey WH. Intersecting roles of protein tyrosine kinase and calcium signaling during fertilization. Cell Calcium 2012. [PMID: 23201334 DOI: 10.1016/j.ceca.2012.11.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The oocyte is a highly specialized cell that must respond to fertilization with a preprogrammed series of signal transduction events that establish a block to polyspermy, trigger resumption of the cell cycle and execution of a developmental program. The fertilization-induced calcium transient is a key signal that initiates the process of oocyte activation and studies over the last several years have examined the signaling pathways that act upstream and downstream of this calcium transient. Protein tyrosine kinase signaling was found to be an important component of the upstream pathways that stimulated calcium release at fertilization in oocytes from animals that fertilize externally, but a similar pathway has not been found in mammals which fertilize internally. The following review will examine the diversity of signaling in oocytes from marine invertebrates, amphibians, fish and mammals in an attempt to understand the basis for the observed differences. In addition to the pathways upstream of the fertilization-induced calcium transient, recent studies are beginning to unravel the role of protein tyrosine kinase signaling downstream of the calcium transient. The PYK2 kinase was found to respond to fertilization in the zebrafish system and seems to represent a novel component of the response of the oocyte to fertilization. The potential impact of impaired PTK signaling in oocyte quality will also be discussed.
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Affiliation(s)
- William H Kinsey
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, United States.
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Dickinson GD, Swaminathan D, Parker I. The probability of triggering calcium puffs is linearly related to the number of inositol trisphosphate receptors in a cluster. Biophys J 2012; 102:1826-36. [PMID: 22768938 DOI: 10.1016/j.bpj.2012.03.029] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 03/12/2012] [Accepted: 03/14/2012] [Indexed: 10/28/2022] Open
Abstract
Puffs are local Ca(2+) signals that arise by Ca(2+) liberation from the endoplasmic reticulum through concerted opening of tightly clustered inositol trisphosphate receptor/channels (IP(3)R). They serve both local signaling functions and trigger global Ca(2+) waves. The numbers of functional IP(3)R within clusters differ appreciably between different puff sites, and we investigated how the probability of puff occurrence varies with cluster size. We imaged puffs in SH-SY5Y cells using total internal fluorescence microscopy, and estimated cluster sizes from the magnitude of the largest puff observed at each site relative to the signal from a single channel. We find that the initial triggering rate of puffs following photorelease of IP(3), and the average frequency of subsequent repetitive puffs, vary about linearly with cluster size. These data accord well with stochastic simulations in which opening of any individual IP(3)R channel within a cluster triggers a puff via Ca(2+)-induced Ca(2+) release. An important consequence is that the signaling power of a puff site (average amount of Ca(2+) released per puff × puff frequency) varies about the square of cluster size, implying that large clusters contribute disproportionately to cellular signaling and, because of their higher puff frequency, preferentially act as pacemakers to initiate Ca(2+) waves.
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Affiliation(s)
- George D Dickinson
- Department of Neurobiology and Behavior, University of California, Irvine, California, USA.
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Haun S, Sun L, Hubrack S, Yule D, Machaca K. Phosphorylation of the rat Ins(1,4,5)P₃ receptor at T930 within the coupling domain decreases its affinity to Ins(1,4,5)P₃. Channels (Austin) 2012; 6:379-84. [PMID: 22878752 PMCID: PMC3508777 DOI: 10.4161/chan.21170] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The Ins(1,4,5)P3 receptor acts as a central hub for Ca2+ signaling by integrating multiple signaling modalities into Ca2+ release from intracellular stores downstream of G-protein and tyrosine kinase-coupled receptor stimulation. As such, the Ins(1,4,5)P3 receptor plays fundamental roles in cellular physiology. The regulation of the Ins(1,4,5)P3 receptor is complex and involves protein-protein interactions, post-translational modifications, allosteric modulation, and regulation of its sub-cellular distribution. Phosphorylation has been implicated in the sensitization of Ins(1,4,5)P3-dependent Ca2+ release observed during oocyte maturation. Here we investigate the role of phosphorylation at T-930, a residue phosphorylated specifically during meiosis. We show that a phosphomimetic mutation at T-930 of the rat Ins(1,4,5)P3 receptor results in decreased Ins(1,4,5)P3-dependent Ca2+ release and lowers the Ins(1,4,5)P3 binding affinity of the receptor. These data, coupled to the sensitization of Ins(1,4,5)P3-dependent Ca2+ release during meiosis, argue that phosphorylation within the coupling domain of the Ins(1,4,5)P3 receptor acts in a combinatorial fashion to regulate Ins(1,4,5)P3 receptor function.
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Affiliation(s)
- Shirley Haun
- University of Arkansas for Medical Sciences, Little Rock, AR, USA
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