1
|
Tokmakov AA, Teranishi R, Sato KI. Spontaneous Overactivation of Xenopus Frog Eggs Triggers Necrotic Cell Death. Int J Mol Sci 2024; 25:5321. [PMID: 38791359 PMCID: PMC11121189 DOI: 10.3390/ijms25105321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/01/2024] [Accepted: 05/03/2024] [Indexed: 05/26/2024] Open
Abstract
The excessive activation of frog eggs, referred to as overactivation, can be initiated by strong oxidative stress, leading to expedited calcium-dependent non-apoptotic cell death. Overactivation also occurs spontaneously, albeit at a low frequency, in natural populations of spawned frog eggs. Currently, the cytological and biochemical events of the spontaneous process have not been characterized. In the present study, we demonstrate that the spontaneous overactivation of Xenopus frog eggs, similarly to oxidative stress- and mechanical stress-induced overactivation, is characterized by the fast and irreversible contraction of the egg's cortical layer, an increase in egg size, the depletion of intracellular ATP, a drastic increase in the intracellular ADP/ATP ratio, and the degradation of M phase-specific cyclin B2. These events manifest in eggs in the absence of caspase activation within one hour of triggering overactivation. Importantly, substantial amounts of ATP and ADP leak from the overactivated eggs, indicating that plasma membrane integrity is compromised in these cells. The rupture of the plasma membrane and acute depletion of intracellular ATP explicitly define necrotic cell death. Finally, we report that egg overactivation can occur in the frog's genital tract. Our data suggest that mechanical stress may be a key factor promoting egg overactivation during oviposition in frogs.
Collapse
Affiliation(s)
- Alexander A. Tokmakov
- Institute of Advanced Technology, Faculty of Biology-Oriented Science and Technology, KinDai University, 930 Nishimitani, Kinokawa City 649-6493, Japan
| | - Ryuga Teranishi
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kita-ku, Kyoto 603-8555, Japan;
| | - Ken-Ichi Sato
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kita-ku, Kyoto 603-8555, Japan;
| |
Collapse
|
2
|
Zoller JA, Parasyraki E, Lu AT, Haghani A, Niehrs C, Horvath S. DNA methylation clocks for clawed frogs reveal evolutionary conservation of epigenetic aging. GeroScience 2024; 46:945-960. [PMID: 37270437 PMCID: PMC10828168 DOI: 10.1007/s11357-023-00840-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 05/25/2023] [Indexed: 06/05/2023] Open
Abstract
To address how conserved DNA methylation-based epigenetic aging is in diverse branches of the tree of life, we generated DNA methylation data from African clawed frogs (Xenopus laevis) and Western clawed frogs (Xenopus tropicalis) and built multiple epigenetic clocks. Dual species clocks were developed that apply to both humans and frogs (human-clawed frog clocks), supporting that epigenetic aging processes are evolutionary conserved outside mammals. Highly conserved positively age-related CpGs are located in neural-developmental genes such as uncx, tfap2d as well as nr4a2 implicated in age-associated disease. We conclude that signatures of epigenetic aging are evolutionary conserved between frogs and mammals and that the associated genes relate to neural processes, altogether opening opportunities to employ Xenopus as a model organism to study aging.
Collapse
Affiliation(s)
- Joseph A Zoller
- Department of Biostatistics, School of Public Health, University of California, Los Angeles, Los Angeles, CA, USA
| | | | - Ake T Lu
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Altos Labs, San Diego, CA, USA
| | - Amin Haghani
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Altos Labs, San Diego, CA, USA
| | - Christof Niehrs
- Institute of Molecular Biology (IMB), Mainz, Germany.
- German Cancer Research Center (DKFZ), Division of Molecular Embryology, DKFZ-ZMBH Alliance, Heidelberg, Germany.
| | - Steve Horvath
- Department of Biostatistics, School of Public Health, University of California, Los Angeles, Los Angeles, CA, USA.
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
- Altos Labs, San Diego, CA, USA.
| |
Collapse
|
3
|
Méndez-Tepepa M, Morales-Cruz C, García-Nieto E, Anaya-Hernández A. A review of the reproductive system in anuran amphibians. ZOOLOGICAL LETTERS 2023; 9:3. [PMID: 36782341 PMCID: PMC9926845 DOI: 10.1186/s40851-023-00201-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 01/18/2023] [Indexed: 06/18/2023]
Abstract
Reproductive biology is an important topic that is well explored in many vertebrates, but information about frogs' reproductive mechanisms could be improved. Therefore, this review aims to provide organized and specific information on frog reproduction. First, we developed schemes that illustrate the general information regarding reproductive biological mechanisms in frogs in a specific way. Then, we described the physiological, histological, and morphological mechanisms of each organ of the reproductive system of male and female frogs. Finally, this manuscript may contribute to a broader understanding of anuran reproductive biology. Since, understanding frogs' reproductive system permits one to make a comparison with reproduction with other anurans.
Collapse
Affiliation(s)
- Maribel Méndez-Tepepa
- Centro de Investigación en Genética y Ambiente, Universidad Autónoma de Tlaxcala, Autopista San Martín-Tlaxcala Km 10.5, Ixtacuixtla, 90120, Tlaxcala, Mexico.
| | - Cuauhtémoc Morales-Cruz
- Centro de Investigación en Genética y Ambiente, Universidad Autónoma de Tlaxcala, Autopista San Martín-Tlaxcala Km 10.5, Ixtacuixtla, 90120, Tlaxcala, Mexico
| | - Edelmira García-Nieto
- Centro de Investigación en Genética y Ambiente, Universidad Autónoma de Tlaxcala, Autopista San Martín-Tlaxcala Km 10.5, Ixtacuixtla, 90120, Tlaxcala, Mexico
| | - Arely Anaya-Hernández
- Centro de Investigación en Genética y Ambiente, Universidad Autónoma de Tlaxcala, Autopista San Martín-Tlaxcala Km 10.5, Ixtacuixtla, 90120, Tlaxcala, Mexico
| |
Collapse
|
4
|
Tokmakov AA, Morichika Y, Teranishi R, Sato KI. Oxidative Stress-Induced Overactivation of Frog Eggs Triggers Calcium-Dependent Non-Apoptotic Cell Death. Antioxidants (Basel) 2022; 11:antiox11122433. [PMID: 36552641 PMCID: PMC9774297 DOI: 10.3390/antiox11122433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022] Open
Abstract
Excessive activation of frog eggs (overactivation) is a pathological process that renders eggs unfertilizable. Its physiological inducers are unknown. Previously, oxidative stress was shown to cause time- and dose-dependent overactivation of Xenopus laevis frog eggs. Here, we demonstrate that the oxidative stress-induced egg overactivation is a calcium-dependent phenomenon which can be attenuated in the presence of the selective calcium chelator BAPTA. Degradation of cyclin B2, which is known to be initiated by calcium transient in fertilized or parthenogenetically activated eggs, can also be observed in the overactivated eggs. Decline in mitochondrial membrane potential, ATP depletion and termination of protein synthesis manifest in the eggs within one hour of triggering overactivation. These intracellular events occur in the absence of caspase activation. Furthermore, plasma membrane integrity is compromised in the overactivated eggs, as evidenced by ATP leakage and egg swelling. In sum, our data demonstrate that oxidative stress-induced overactivation of frog eggs causes fast and dramatic disruption of cellular homeostasis, resulting in robust and expedited cell death by a calcium-dependent non-apoptotic mechanism.
Collapse
Affiliation(s)
- Alexander A. Tokmakov
- Institute of Advanced Technoogy, Faculty of Biology-Oriented Science and Technology, KinDai University, 930 Nishimitani, Kinokawa City 649-6493, Japan
- Correspondence:
| | - Yudai Morichika
- Laboratory of Cell Signaling and Development, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan
| | - Ryuga Teranishi
- Laboratory of Cell Signaling and Development, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan
| | - Ken-Ichi Sato
- Laboratory of Cell Signaling and Development, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan
| |
Collapse
|
5
|
Modulation of Intracellular ROS and Senescence-Associated Phenotypes of Xenopus Oocytes and Eggs by Selective Antioxidants. Antioxidants (Basel) 2021; 10:antiox10071068. [PMID: 34356301 PMCID: PMC8301133 DOI: 10.3390/antiox10071068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/24/2021] [Accepted: 06/28/2021] [Indexed: 11/17/2022] Open
Abstract
Aging of oocytes and eggs diminishes their reproductive and developmental potential. It has been demonstrated previously that reactive oxygen species (ROS) contribute to accelerated aging of various cells. In the present study, we measured intracellular levels of ROS and investigated effects of several selective antioxidants (AOXs) on the viability and functional activity of aging oocytes and eggs of the African clawed frog Xenopus laevis. The fluorescent cell-permeable dye DCFDA, which is widely employed for ROS detection in cultured mammalian cells, was used to monitor ROS levels in the fresh and bench-aged oocytes and eggs by an optimized protocol. It was found that intracellular ROS contents were increased in frog oocytes and eggs aged for 48 h. It was further demonstrated using selective cell-permeable AOXs targeting different ROS-generating mechanisms, that the major source of ROS in Xenopus oocytes and eggs is the plasma membrane NADPH oxidase, and that mitochondrial generation contributes to the intracellular ROS content to a lesser extent. Targeted inhibition of NADPH oxidase with a natural organic compound apocynin reduced ROS levels significantly in Xenopus oocytes and eggs, maintained their normal phenotype and supported their functional competence. To our knowledge this is the first report concerning beneficial effects of apocynin on the isolated gamete cells, such as oocytes and eggs.
Collapse
|
6
|
Tokmakov AA, Stefanov VE, Sato KI. Dissection of the Ovulatory Process Using ex vivo Approaches. Front Cell Dev Biol 2020; 8:605379. [PMID: 33363163 PMCID: PMC7755606 DOI: 10.3389/fcell.2020.605379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 11/19/2020] [Indexed: 12/23/2022] Open
Abstract
Ovulation is a unique physiological phenomenon that is essential for sexual reproduction. It refers to the entire process of ovarian follicle responses to hormonal stimulation resulting in the release of mature fertilization-competent oocytes from the follicles and ovaries. Remarkably, ovulation in different species can be reproduced out-of-body with high fidelity. Moreover, most of the molecular mechanisms and signaling pathways engaged in this process have been delineated using in vitro ovulation models. Here, we provide an overview of the major molecular and cytological events of ovulation observed in frogs, primarily in the African clawed frog Xenopus laevis, using mainly ex vivo approaches, with the focus on meiotic oocyte maturation and follicle rupture. For the purpose of comparison and generalization, we also refer extensively to ovulation in other biological species, most notoriously, in mammals.
Collapse
Affiliation(s)
| | - Vasily E Stefanov
- Department of Biochemistry, Saint Petersburg State University, Saint Petersburg, Russia
| | - Ken-Ichi Sato
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
| |
Collapse
|
7
|
Sato K, Tokmakov AA. Toward the understanding of biology of oocyte life cycle in Xenopus Laevis: No oocytes left behind. Reprod Med Biol 2020; 19:114-119. [PMID: 32273815 PMCID: PMC7138939 DOI: 10.1002/rmb2.12314] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 12/09/2019] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND For the past more than 25 years, we have been focusing on the developmental and reproductive biology of the female gametes, oocytes, and eggs, of the African clawed frog Xenopus laevis. METHODS The events associated with the life cycle of these cells can be classified into the four main categories: first, oogenesis and cell growth in the ovary during the first meiotic arrest; second, maturation and ovulation that occur simultaneously and result in the acquisition of fertilization competence and the second meiotic arrest; third, fertilization, that is sperm-induced transition from egg to zygote; and fourth, egg death after spontaneous activation in the absence of fertilizing sperm. MAIN FINDINGS Our studies have demonstrated that signal transduction system involving tyrosine kinase Src and other oocyte/egg membrane-associated molecules such as uroplakin III and some other cytoplasmic proteins such as mitogen-activated protein kinase (MAPK) play important roles for successful ovulation, maturation, fertilization, and initiation of embryonic development. CONCLUSION We summarize recent advances in understanding cellular and molecular mechanisms underlying life cycle events of the oocytes and eggs. Our further intention is to discuss and predict potentially promising impact of the recent findings on the challenges facing reproductive biology and medicine, as well as societal contexts.
Collapse
Affiliation(s)
- Ken‐ichi Sato
- Laboratory of Cell Signaling and DevelopmentDepartment of Industrial Life SciencesFaculty of Life SciencesKyoto Sangyo UniversityKyotoJapan
| | - Alexander A. Tokmakov
- Laboratory of Cell Signaling and DevelopmentDepartment of Industrial Life SciencesFaculty of Life SciencesKyoto Sangyo UniversityKyotoJapan
| |
Collapse
|
8
|
Tokmakov AA, Akino K, Iguchi S, Iwasaki T, Stefanov VE, Sato KI. Autophosphorylation of MAP kinase disables the MAPK pathway in apoptotic Xenopus eggs. Biochem Biophys Res Commun 2019; 517:140-145. [PMID: 31320137 DOI: 10.1016/j.bbrc.2019.07.033] [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: 07/05/2019] [Accepted: 07/10/2019] [Indexed: 11/26/2022]
Abstract
Mitogen-activated protein kinases (MAPKs) are involved in the regulation of various cellular processes, including cell survival and apoptosis. Here, we report that Xenopus p42 MAPK becomes phosphorylated in apoptotic eggs, however this modification does not activate the enzyme. Using phosphorylation residue-specific antibodies, we demonstrate that this modification occurs on the Tyr residue in the MAPK activation segment, pinpointing the autophosphorylation mechanism. Notably, MAPK phosphorylation in apoptotic Xenopus eggs coincides with prominent intracellular acidification accompanying apoptosis in these cells. Furthermore, autophosphorylation of recombinant Xenopus MAPK is stimulated and phosphorylation of a protein substrate is inhibited under low pH conditions. Thus, acidic intracellular conditions inactivate MAPK and effectively disable the MAPK-mediated survival pathway in the apoptotic eggs. Given that cell acidification is a rather common feature of apoptosis, we hypothesize that stimulation of MAPK autophosphorylation and shutdown of the MAPK pathway may represent universal traits of apoptotic cell death.
Collapse
Affiliation(s)
| | - Kousuke Akino
- Graduate School of Science Faculty of Science, Kobe University, Japan
| | - Sho Iguchi
- Biosignal Research Center, Kobe University, Japan
| | - Tetsushi Iwasaki
- Graduate School of Science Faculty of Science, Kobe University, Japan; Biosignal Research Center, Kobe University, Japan
| | - Vasily E Stefanov
- Department of Biochemistry, Saint Petersburg State University, Russia
| | - Ken-Ichi Sato
- Faculty of Life Sciences, Kyoto Sangyo University, Japan
| |
Collapse
|
9
|
Biochemical Hallmarks of Oxidative Stress-Induced Overactivation of Xenopus Eggs. BIOMED RESEARCH INTERNATIONAL 2019; 2019:7180540. [PMID: 31341903 PMCID: PMC6634078 DOI: 10.1155/2019/7180540] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/28/2019] [Accepted: 05/28/2019] [Indexed: 02/05/2023]
Abstract
Egg overactivation occurs with a low frequency in the populations of naturally ovulated frog eggs. At present, its natural inducers, molecular mechanisms, and intracellular events remain unknown. Using microscopic and biochemical analyses, we demonstrate here that high levels of hydrogen peroxide-induced oxidative stress can cause time- and dose-dependent overactivation of Xenopus eggs. Lipofuscin accumulation, decrease of soluble cytoplasmic protein content, and depletion of intracellular ATP were found to take place in the overactivated eggs. Progressive development of these processes suggests that egg overactivation unfolds in a sequential and ordered fashion.
Collapse
|
10
|
Tokmakov AA, Sato KI. Activity and intracellular localization of senescence-associated β-galactosidase in aging Xenopus oocytes and eggs. Exp Gerontol 2019; 119:157-167. [PMID: 30769028 DOI: 10.1016/j.exger.2019.02.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 01/22/2019] [Accepted: 02/02/2019] [Indexed: 12/14/2022]
Abstract
Senescence-associated β-galactosidase (SA-β-gal) serves as a marker of senescence in aging somatic cells. However, little is known about SA-β-gal dynamics in aging gamete cells. To address this issue, here we investigated activity and intracellular localization of SA-β-gal in freshly obtained and aging oocytes and eggs of the African clawed frog Xenopus laevis. Data base mining revealed the presence of several homologous β-galactosidase sequences in the annotated Xenopus genome. Some of them were predicted to contain an N-terminal signal peptide sequence, suggesting enzyme translocation to cellular organelles. Biochemical and microscopic analyses confirmed SA-β-gal localization in the particulate and cytosolic fractions of oocytes and eggs. SA-β-gal activity was found to reside predominantly within a fraction of dense cytoplasmic granules that were extensively stained with the lysosome-specific dye LysoTracker Green DND-26 and had an average size of 8.9 ± 5.6 μm. These features identify the SA-β-gal-containing granules as a subpopulation of yolk platelets, specialized late endosomes or lysosomes that accumulate and store processed protein in frog oocytes. Further analysis revealed an increase of SA-β-gal activity in Xenopus eggs, but not in oocytes, aged in vitro over 48 h. Our data suggest that endosomal acidification during egg aging may be responsible for this increase.
Collapse
Affiliation(s)
- Alexander A Tokmakov
- Department of Molecular Biosciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan.
| | - Ken-Ichi Sato
- Department of Molecular Biosciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan.
| |
Collapse
|
11
|
Sato KI, Tokmakov AA. Membrane Microdomains as Platform to Study Membrane-Associated Events During Oogenesis, Meiotic Maturation, and Fertilization in Xenopus laevis. Methods Mol Biol 2019; 1920:59-73. [PMID: 30737686 DOI: 10.1007/978-1-4939-9009-2_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Studies on the egg plasma membrane-associated tyrosine kinase Src have shed light on the identity of the molecular machinery that is responsible for gamete interaction and possibly fusion in African clawed frog Xenopus laevis. Here we describe our protocol for identifying and analyzing molecular and cellular machinery that contributes to a variety of biological processes in the course of oogenesis, oocyte maturation, egg fertilization, and early embryogenesis in Xenopus. Our current special interest is to evaluate the hypothesis that the oocyte/egg membrane microdomain (MD)-associated uroplakin III-Src system is responsible for mediating sperm-egg membrane interaction/fusion signal to the oocyte/egg cytoplasm to initiate embryonic and zygotic development in this species. Therefore, this chapter contains a brief introduction to biology of oocytes and eggs in Xenopus and addresses the following questions: (1) What is oocyte/egg MD? (2) Why do we study oocyte/egg MD? (3) How to manipulate oocyte/egg MD? (4) What has been achieved by oocyte/egg MD studies? (5) What are the next steps in oocyte/egg MD studies?
Collapse
Affiliation(s)
- Ken-Ichi Sato
- Faculty of Life Sciences, Laboratory of Cell Signaling and Development, Department of Molecular Biosciences, Kyoto Sangyo University, Kyoto, Japan.
| | - Alexander A Tokmakov
- Faculty of Life Sciences, Laboratory of Cell Signaling and Development, Department of Molecular Biosciences, Kyoto Sangyo University, Kyoto, Japan
| |
Collapse
|
12
|
Dilsaver MR, Chen P, Thompson TA, Reusser T, Mukherjee RN, Oakey J, Levy DL. Emerin induces nuclear breakage in Xenopus extract and early embryos. Mol Biol Cell 2018; 29:3155-3167. [PMID: 30332321 PMCID: PMC6340207 DOI: 10.1091/mbc.e18-05-0277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Emerin is an inner nuclear membrane protein often mutated in Emery–Dreifuss muscular dystrophy. Because emerin has diverse roles in nuclear mechanics, cytoskeletal organization, and gene expression, it has been difficult to elucidate its contribution to nuclear structure and disease pathology. In this study, we investigated emerin’s impact on nuclei assembled in Xenopus laevis egg extract, a simplified biochemical system that lacks potentially confounding cellular factors and activities. Notably, these extracts are transcriptionally inert and lack endogenous emerin and filamentous actin. Strikingly, emerin caused rupture of egg extract nuclei, dependent on the application of shear force. In egg extract, emerin localized to nonnuclear cytoplasmic membranes, and nuclear rupture was rescued by targeting emerin to the nucleus, disrupting its membrane association, or assembling nuclei with lamin A. Furthermore, emerin induced breakage of nuclei in early-stage X. laevis embryo extracts, and embryos microinjected with emerin were inviable, with ruptured nuclei. We propose that cytoplasmic membrane localization of emerin leads to rupture of nuclei that are more sensitive to mechanical perturbation, findings that may be relevant to early development and certain laminopathies.
Collapse
Affiliation(s)
- Matthew R Dilsaver
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071
| | - Pan Chen
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071
| | - Trey A Thompson
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071
| | - Traci Reusser
- Department of Chemical Engineering, University of Wyoming, Laramie, WY 82071
| | - Richik N Mukherjee
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071
| | - John Oakey
- Department of Chemical Engineering, University of Wyoming, Laramie, WY 82071
| | - Daniel L Levy
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071
| |
Collapse
|
13
|
Cheng X, Ferrell JE. Apoptosis propagates through the cytoplasm as trigger waves. Science 2018; 361:607-612. [PMID: 30093599 DOI: 10.1126/science.aah4065] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 12/15/2017] [Accepted: 07/03/2018] [Indexed: 11/02/2022]
Abstract
Apoptosis is an evolutionarily conserved form of programmed cell death critical for development and tissue homeostasis in animals. The apoptotic control network includes several positive feedback loops that may allow apoptosis to spread through the cytoplasm in self-regenerating trigger waves. We tested this possibility in cell-free Xenopus laevis egg extracts and observed apoptotic trigger waves with speeds of ~30 micrometers per minute. Fractionation and inhibitor studies implicated multiple feedback loops in generating the waves. Apoptotic oocytes and eggs exhibited surface waves with speeds of ~30 micrometers per minute, which were tightly correlated with caspase activation. Thus, apoptosis spreads through trigger waves in both extracts and intact cells. Our findings show how apoptosis can spread over large distances within a cell and emphasize the general importance of trigger waves in cell signaling.
Collapse
Affiliation(s)
- Xianrui Cheng
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305-5174, USA
| | - James E Ferrell
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305-5174, USA. .,Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305-5307, USA
| |
Collapse
|
14
|
Tokmakov AA, Sato KI, Stefanov VE. Postovulatory cell death: why eggs die via apoptosis in biological species with external fertilization. J Reprod Dev 2017; 64:1-6. [PMID: 29081453 PMCID: PMC5830352 DOI: 10.1262/jrd.2017-100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Spawned unfertilized eggs have been found to die by apoptosis in several species with external fertilization. However, there is no necessity for the externally laid eggs to degrade via this process, as apoptosis evolved as a mechanism to reduce the damaging effects of individual cell death on the whole organism. The recent observation of egg degradation in the genital tracts of some oviparous species provides a clue as to the physiological relevance of egg apoptosis in these animals. We hypothesize that egg apoptosis accompanies ovulation in species with external fertilization as a normal process to eliminate mature eggs retained in the genital tract after ovulation. Furthermore, apoptosis universally develops in ovulated eggs after spontaneous activation in the absence of fertilization. This paper provides an overview of egg apoptosis in several oviparous biological species, including frog, fish, sea urchin, and starfish.
Collapse
Affiliation(s)
| | - Ken-Ichi Sato
- Department of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan
| | - Vasily E Stefanov
- Department of Biochemistry, St. Petersburg State University, St. Petersburg 199034, Russia
| |
Collapse
|
15
|
Tokmakov AA, Iguchi S, Iwasaki T, Fukami Y, Sato KI. Global decay of mRNA is a hallmark of apoptosis in aging Xenopus eggs. RNA Biol 2017; 14:339-346. [PMID: 28045588 PMCID: PMC5367254 DOI: 10.1080/15476286.2016.1276695] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Cytoplasmic mRNAs are specifically degraded in somatic cells as a part of early apoptotic response. However, no reports have been presented so far concerning mRNA fate in apoptotic gametes. In the present study, we analyzed the content of various cytoplasmic mRNAs in aging oocytes and eggs of the African clawed frog, Xenopus laevis. To circumvent large gene expression variation among the individual oocytes and eggs, single-cell monitoring of transcript levels has been implemented, using multiple cytoplasmic collections and reverse transcriptase quantitative PCR. It was found that numerous cytoplasmic mRNAs, coding for proteins classified in different functional types, are robustly degraded in apoptotic Xenopus eggs, but not in aging oocytes. mRNA degradation becomes evident in the eggs after meiotic exit at the time of cytochrome c release. A strong correlation between the length of PCR amplicon and specific transcript content was observed, suggesting endonucleolytic cleavage of mRNA. In addition, it was found that mRNA deadenylation also contributes to apoptotic mRNA degradation. Altogether, these findings indicate that the global decay of mRNA represents a hallmark of apoptosis in aging Xenopus eggs. To our knowledge, this is the first description of mRNA degradation in apoptotic gamete cells.
Collapse
Affiliation(s)
- Alexander A Tokmakov
- a Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo Motoyama , Kita ku , Kyoto , Japan.,b Graduate School of Science, Kobe University, Rokko dai , Nada , Kobe , Japan
| | - Sho Iguchi
- b Graduate School of Science, Kobe University, Rokko dai , Nada , Kobe , Japan
| | - Tetsushi Iwasaki
- b Graduate School of Science, Kobe University, Rokko dai , Nada , Kobe , Japan
| | - Yasuo Fukami
- b Graduate School of Science, Kobe University, Rokko dai , Nada , Kobe , Japan
| | - Ken-Ichi Sato
- a Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo Motoyama , Kita ku , Kyoto , Japan
| |
Collapse
|
16
|
Stricker SA, Beckstrom B, Mendoza C, Stanislawski E, Wodajo T. Oocyte aging in a marine protostome worm: The roles of maturation-promoting factor and extracellular signal regulated kinase form of mitogen-activated protein kinase. Dev Growth Differ 2016; 58:250-9. [PMID: 26918273 DOI: 10.1111/dgd.12269] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 12/29/2015] [Accepted: 01/10/2016] [Indexed: 12/15/2022]
Abstract
The roles of maturation-promoting factor (MPF) and an extracellular signal regulated kinase form of mitogen-activated protein kinase (ERK MAPK) are analyzed during oocyte aging in the marine protostome worm Cerebratulus. About a day after removal from the ovary, unfertilized metaphase-I-arrested oocytes of Cerebratulus begin to flatten and swell before eventually lysing, thereby exhibiting characteristics of a necroptotic mode of regulated cell death. Based on immunoblots probed with phospho-specific antibodies, MPF and ERK are initially active in freshly mature specimens. However, as oocytes age, both kinase activities decline, with ERK deactivation occurring well before MPF downregulation. Experiments using pharmacological modulators indicate that oocyte degradation is promoted by the maturation-initiated activation of ERK as well as by the deactivation of MPF that occurs in extensively aged specimens. The potential significance of these findings is discussed relative to previously published results for apoptotic eggs and oocytes of echinoderm and vertebrate deuterostomes.
Collapse
Affiliation(s)
- Stephen A Stricker
- Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM, 87131, USA
| | - Bradley Beckstrom
- Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM, 87131, USA
| | - Cristina Mendoza
- Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM, 87131, USA
| | - Emma Stanislawski
- Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM, 87131, USA
| | - Tewodros Wodajo
- Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM, 87131, USA
| |
Collapse
|
17
|
Sato KI. Transmembrane signal transduction in oocyte maturation and fertilization: focusing on Xenopus laevis as a model animal. Int J Mol Sci 2014; 16:114-34. [PMID: 25546390 PMCID: PMC4307238 DOI: 10.3390/ijms16010114] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 12/15/2014] [Indexed: 11/16/2022] Open
Abstract
Fertilization is a cell biological phenomenon of crucial importance for the birth of new life in a variety of multicellular and sexual reproduction species such as algae, animal and plants. Fertilization involves a sequence of events, in which the female gamete "egg" and the male gamete "spermatozoon (sperm)" develop, acquire their functions, meet and fuse with each other, to initiate embryonic and zygotic development. Here, it will be briefly reviewed how oocyte cytoplasmic components are orchestrated to undergo hormone-induced oocyte maturation and sperm-induced activation of development. I then review how sperm-egg membrane interaction/fusion and activation of development in the fertilized egg are accomplished and regulated through egg coat- or egg plasma membrane-associated components, highlighting recent findings and future directions in the studies using Xenopus laevis as a model experimental animal.
Collapse
Affiliation(s)
- Ken-ichi Sato
- Laboratory of Cell Signaling and Development, Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan.
| |
Collapse
|