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Lestari B, Fukushima T, Utomo RY, Wahyuningsih MSH. Apoptotic and non-apoptotic roles of caspases in placenta physiology and pathology. Placenta 2024; 151:37-47. [PMID: 38703713 DOI: 10.1016/j.placenta.2024.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 03/12/2024] [Accepted: 03/27/2024] [Indexed: 05/06/2024]
Abstract
Caspases, a family of cysteine proteases, are pivotal regulators of apoptosis, the tightly controlled cell death process crucial for eliminating excessive or unnecessary cells during development, including placental development. Collecting research has unveiled the multifaceted roles of caspases in the placenta, extending beyond apoptosis. Apart from their involvement in placental tissue remodeling via apoptosis, caspases actively participate in essential regulatory processes, such as trophoblast fusion and differentiation, significantly influencing placental growth and functionality. In addition, growing evidence indicates an elevation in caspase activity under pathological conditions like pre-eclampsia (PE) and intrauterine growth restriction (IUGR), leading to excessive cell death as well as inflammation. Drawing from advancements in caspase research and placental development under both normal and abnormal conditions, we examine the significance of caspases in both cell death (apoptosis) and non-cell death-related processes within the placenta. We also discuss potential therapeutics targeting caspase-related pathways for placenta disorders.
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Affiliation(s)
- Beni Lestari
- Department Pharmacology and Therapy, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia; Cancer Chemoprevention Research Center, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Toshiaki Fukushima
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Japan.
| | - Rohmad Yudi Utomo
- Cancer Chemoprevention Research Center, Universitas Gadjah Mada, Yogyakarta, Indonesia; Department Pharmaceutical Chemistry, Faculty of Pharmacy, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Mae Sri Hartati Wahyuningsih
- Department Pharmacology and Therapy, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia.
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Renaud SJ, Jeyarajah MJ. How trophoblasts fuse: an in-depth look into placental syncytiotrophoblast formation. Cell Mol Life Sci 2022; 79:433. [PMID: 35859055 PMCID: PMC11072895 DOI: 10.1007/s00018-022-04475-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 05/07/2022] [Accepted: 07/06/2022] [Indexed: 11/24/2022]
Abstract
In humans, cell fusion is restricted to only a few cell types under normal conditions. In the placenta, cell fusion is a critical process for generating syncytiotrophoblast: the giant multinucleated trophoblast lineage containing billions of nuclei within an interconnected cytoplasm that forms the primary interface separating maternal blood from fetal tissue. The unique morphology of syncytiotrophoblast ensures that nutrients and gases can be efficiently transferred between maternal and fetal tissue while simultaneously restricting entry of potentially damaging substances and maternal immune cells through intercellular junctions. To maintain integrity of the syncytiotrophoblast layer, underlying cytotrophoblast progenitor cells terminate their capability for self-renewal, upregulate expression of genes needed for differentiation, and then fuse into the overlying syncytium. These processes are disrupted in a variety of obstetric complications, underscoring the importance of proper syncytiotrophoblast formation for pregnancy health. Herein, an overview of key mechanisms underlying human trophoblast fusion and syncytiotrophoblast development is discussed.
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Affiliation(s)
- Stephen J Renaud
- Department of Anatomy and Cell Biology and Children's Health Research Institute, University of Western Ontario, London, ON, N6A5C1, Canada.
| | - Mariyan J Jeyarajah
- Department of Anatomy and Cell Biology and Children's Health Research Institute, University of Western Ontario, London, ON, N6A5C1, Canada
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Zhang Y, Le T, Grabau R, Mohseni Z, Kim H, Natale DR, Feng L, Pan H, Yang H. TMEM16F phospholipid scramblase mediates trophoblast fusion and placental development. SCIENCE ADVANCES 2020; 6:eaba0310. [PMID: 32494719 PMCID: PMC7202889 DOI: 10.1126/sciadv.aba0310] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 02/19/2020] [Indexed: 05/12/2023]
Abstract
Cell-cell fusion or syncytialization is fundamental to the reproduction, development, and homeostasis of multicellular organisms. In addition to various cell type-specific fusogenic proteins, cell surface externalization of phosphatidylserine (PS), a universal eat-me signal in apoptotic cells, has been observed in different cell fusion events. Nevertheless, the molecular underpinnings of PS externalization and cellular mechanisms of PS-facilitated cell-cell fusion are unclear. Here, we report that TMEM16F, a Ca2+-activated phospholipid scramblase (CaPLSase), plays an essential role in placental trophoblast fusion by translocating PS to cell surface independent of apoptosis. The placentas from the TMEM16F knockout mice exhibit deficiency in trophoblast syncytialization and placental development, which lead to perinatal lethality. We thus identified a new biological function of TMEM16F CaPLSase in trophoblast fusion and placental development. Our findings provide insight into understanding cell-cell fusion mechanism of other cell types and on mitigating pregnancy complications such as miscarriage, intrauterine growth restriction, and preeclampsia.
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Affiliation(s)
- Yang Zhang
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
| | - Trieu Le
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
| | - Ryan Grabau
- The USF Health Heart Institute, University of South Florida, Tampa, FL, USA
| | - Zahra Mohseni
- Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC, USA
| | - Hoejeong Kim
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Diego, La Jolla, CA, USA
| | - David R. Natale
- Departments of Obstetrics and Gynaecology and Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Liping Feng
- Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC, USA
- MOE-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Jiao Tong University School of Medicine, Shanghai, China
| | - Hua Pan
- The USF Health Heart Institute, University of South Florida, Tampa, FL, USA
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA
- Corresponding author.
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Abstract
INTRODUCTION Cell-free "fetal" DNA is released from the placenta. Because the fetal membranes also arise from the trophectoderm layer of the blastocyst, these studies sought to test the hypothesis that the membranes also release cell-free DNA (cfDNA). METHODS Fetal membranes were harvested from pregnant CD-1 mice and cultured in 12-well plates containing media alone or with staurosporine and thapsigargin (apoptosis stimulators), Q-VD-OPh (caspase inhibitor), Trolox (vitamin E analog), and lipopolysaccharide and tumor necrosis factor α (TNFα; inflammatory mediators). The cfDNA in the media was extracted, quantified, and normalized for tissue weight. Media was used for a lactate dehydrogenase (LDH) assay. Membrane homogenates were used to assess activated caspase levels and the expression of DNA fragmentation factor B (DFFB) and BAX proteins. 5-Methylcytosine was assessed using a 5-mC DNA enzyme-linked immunosorbent assay. The cfDNA was used to stimulate interleukin 6 (IL6) release by J774A.1 mouse macrophage cells. RESULTS Increased cfDNA release at 6 and 21 hours occurred in parallel with increasing LDH levels. The cfDNA concentrations were significantly suppressed by Q-VD-OPh and Trolox and increased by thapsigargin and TNFα. Increased caspase activity was suppressed by Q-VD-OPh and increased by TNFα, thapsigargin, and staurosporine. The expression of BAX and DFFB proteins significantly increased by 21 hours. 5-Methylcytosine levels were significantly lower in fetal membranes and placentas and below detectable in the cfDNA released by the explants. The cfDNA-stimulated IL6 release by macrophage cells was suppressed by chloroquine, a Toll-like receptor 9 (TLR9) inhibitor. CONCLUSIONS These studies have confirmed cfDNA release by the mouse fetal membranes; cfDNA was markedly hypomethylated and a robust stimulator of TLR9.
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Affiliation(s)
- Michala R Sawyer
- Division of Maternal-Fetal Medicine and the Vincent Center for Reproductive Biology, Department of Obstetrics & Gynecology, Massachusetts General Hospital, 55 Fruit Street, Thier Bldg. 9-911, Boston, MA, 02114, USA
| | - Sharareh Adeli
- Division of Maternal-Fetal Medicine and the Vincent Center for Reproductive Biology, Department of Obstetrics & Gynecology, Massachusetts General Hospital, 55 Fruit Street, Thier Bldg. 9-911, Boston, MA, 02114, USA
| | - Mark Phillippe
- Division of Maternal-Fetal Medicine and the Vincent Center for Reproductive Biology, Department of Obstetrics & Gynecology, Massachusetts General Hospital, 55 Fruit Street, Thier Bldg. 9-911, Boston, MA, 02114, USA.
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Abstract
Although suggested that “fetal” cell-free DNA (cfDNA) is derived from trophoblast cells, the exact origin is unclear. The studies in this report sought to demonstrate that placental tissue releases cfDNA in parallel with cell death, that the size range of cfDNA is similar to that found in maternal plasma, and that the cfDNA fragments are able to stimulate a proinflammatory cytokine response. Placentas were harvested from near term pregnant CD-1 mice and cultured in DMEM/Ham’s F12/FBS media in 8% or 21% O2. After centrifugation to remove cells and cellular debris, the cfDNA was extracted from the media and quantified by DNA spectrophotometry. The cfDNA fragments were sized using a 1.5% TAE gel. Cell death was quantified by lactate dehydrogenase assay; and tissue homogenates were used to quantify caspase activity and BAX expression. Cultured RAW-264.7 macrophage cells were used to determine IL6 stimulation by cfDNA. The cfDNA levels released in 8% O2 (placental normoxia) were not significantly different from explants cultured in 21% O2 (placental hyperoxia). The cfDNA fragments ranged in size from < 100 –< 400 bp. The cfDNA release increased when cultured with LPS, whereas it decreased with trolox (vitamin E analog). Explant release of cfDNA increased in parallel with cell death. The cfDNA release and cell death of trophoblast appears to involve components of the apoptosis signaling pathway as suggested by LPS enhancement of placental caspase activity, suppression of cfDNA release by a pan-caspase inhibitor and the trend toward increased Bax protein expression. Studies with cultured macrophage cells confirmed the ability of cfDNA to stimulate an IL6 response. In summary, these studies have confirmed the ability of placental tissue to release significant amounts of cfDNA, a phenomenon that appears to be mediated, at least in part, by apoptosis; and that the cfDNA released by the placental explants is able to stimulate a significant proinflammatory response. Thus, these studies provide support for the hypothesis that cell-free fetal DNA released by placental tissue potentially plays a mechanistically important role during the events leading to the onset of parturition.
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Affiliation(s)
- Mark Phillippe
- Vincent Center for Reproductive Biology, Department of Obstetrics & Gynecology, Massachusetts General Hospital, Boston, MA
- * E-mail:
| | - Sharareh Adeli
- Vincent Center for Reproductive Biology, Department of Obstetrics & Gynecology, Massachusetts General Hospital, Boston, MA
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Costa MA. Scrutinising the regulators of syncytialization and their expression in pregnancy-related conditions. Mol Cell Endocrinol 2016; 420:180-93. [PMID: 26586208 DOI: 10.1016/j.mce.2015.11.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/05/2015] [Accepted: 11/09/2015] [Indexed: 12/16/2022]
Abstract
The placenta is important for the success of gestation and foetal development. In fact, this specialized pregnancy organ is essential for foetal nourishment, support, and protection. In the placenta, there are different cell populations, including four subtypes of trophoblasts. Cytotrophoblasts fuse and differentiate into the multinucleated syncytiotrophoblast (syncytialization). Syncytialization is a hallmark of placentation and is highly regulated by numerous molecules with distinct roles. Placentas from pregnancies complicated by preeclampsia, intrauterine growth restriction or trisomy 21 have been associated with a defective syncytialization and an altered expression of its modulators. This work proposes to review the molecules that promote or inhibit both fusion and biochemical differentiation of cytotrophoblasts. Moreover, it will also analyse the syncytialization modulators abnormally expressed in pathological placentas, highlighting the molecules that may contribute to the aetiology of these diseases.
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Affiliation(s)
- M A Costa
- Faculdade de Farmácia, Universidade do Porto, Porto, Portugal.
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Costa MA, Keating E, Fonseca BM, Teixeira NA, Correia-da-Silva G. 2-Arachidonoylglycerol impairs human cytotrophoblast cells syncytialization: influence of endocannabinoid signalling in placental development. Mol Cell Endocrinol 2015; 399:386-94. [PMID: 25199616 DOI: 10.1016/j.mce.2014.09.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 09/04/2014] [Accepted: 09/04/2014] [Indexed: 11/16/2022]
Abstract
A balanced cytotrophoblast cell turnover is crucial for placental development and anomalies in this process associated with gestational diseases. The endocannabinoid system (ECS) has emerged as a new player in several biological processes. However, its influence during placental development is still unknown. We report here the expression of the endocannabinoid 2-arachidonoylglycerol (2-AG) main metabolic enzymes in human cytotrophoblasts and syncytiotrophoblast. We also showed that 2-AG induced a decrease in placental alkaline phosphatase activity, human chorionic gonadotropin secretion and Leptin mRNA levels. Moreover, 2-AG reduced glial cell missing 1 and syncytin-2 transcription and the number of nuclei in syncytium. These effects were mediated by cannabinoid receptors and may result from 2-AG inhibition of the cAMP/PKA signalling pathway. Our data suggest that 2-AG may interfere with the biochemical and morphological differentiation of human cytotrophoblasts, through a CB receptor-dependent mechanism, shedding light on a role for the ECS in placental development.
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Affiliation(s)
- M A Costa
- Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Celular e Molecular da Universidade do Porto (IBMC), Porto, Portugal
| | - E Keating
- Departmento de Bioquímica U38FCT, Faculdade de Medicina, Universidade do Porto, Porto, Portugal; Center for Biotechnology and Fine Chemistry, School of Biotechnology, Portuguese Catholic University, Porto, Portugal
| | - B M Fonseca
- Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Celular e Molecular da Universidade do Porto (IBMC), Porto, Portugal
| | - N A Teixeira
- Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Celular e Molecular da Universidade do Porto (IBMC), Porto, Portugal
| | - G Correia-da-Silva
- Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Celular e Molecular da Universidade do Porto (IBMC), Porto, Portugal.
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Costa MA, Fonseca BM, Teixeira NA, Correia-da-Silva G. The endocannabinoid anandamide induces apoptosis in cytotrophoblast cells: involvement of both mitochondrial and death receptor pathways. Placenta 2014; 36:69-76. [PMID: 25465706 DOI: 10.1016/j.placenta.2014.10.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 10/15/2014] [Accepted: 10/21/2014] [Indexed: 11/28/2022]
Abstract
INTRODUCTION A balanced proliferation, apoptosis and differentiation in trophoblast cells of the human placenta is crucial for a proper placental development. Alteration in trophoblast apoptosis and differentiation are associated with gestational-related complications, such as preeclampsia, intrauterine growth restriction or miscarriages. The endocannabinoids (eCBs) have been recognized as new interveners in pregnancy events such as implantation and decidualization. However, their importance in placentation is poorly understood. We hypothesise that these novel lipid mediators may intervene in cytotrophoblast apoptosis and, concomitantly, have a role during placental development. METHODS primary human cytotrophoblasts (hCTs) and the human trophoblast-like choriocarcinoma cell line BeWo cells were exposed to Anandamide (AEA). It was investigated the cellular pathways involved in cell death, by the assessment of cell morphology, caspases activity, mitochondrial membrane potential (Δψm), reactive oxygen/nitrogen species (ROS/RNS) and western blot of cleaved Poly (ADP-ribose) polymerase 1 (PARP-1), truncated Bid (t-Bid) and IκB-α. RESULTS AEA decreased hCTs viability and induced morphological features of apoptosis (chromatin condensation and fragmentation), caspase-3/7 activation and PARP-1 cleavage. In BeWo, AEA also increased the activities of caspase-3/7 and 9, induced loss in Δψm and production of ROS/RNS. These effects were reversed by either CB1 or CB2 antagonists, whereas the increase in caspase-3/7 activity was only reversed with CB2 blockage. AEA-treated cells showed increased caspase-8 activation and formation of t-Bid, suggesting the interplay between intrinsic and extrinsic apoptotic pathways. AEA also increased IκB-α expression, a NF-κB regulatory protein. CONCLUSION Our results highlight the importance of eCBs in cytotrophoblast cell apoptosis and indicate that a crosstalk between intrinsic and extrinsic apoptotic pathways is involved in AEA-induced effects.
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Affiliation(s)
- M A Costa
- Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular da Universidade do Porto (IBMC), Porto, Portugal
| | - B M Fonseca
- Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular da Universidade do Porto (IBMC), Porto, Portugal
| | - N A Teixeira
- Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular da Universidade do Porto (IBMC), Porto, Portugal
| | - G Correia-da-Silva
- Departamento de Ciências Biológicas, Laboratório de Bioquímica, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular da Universidade do Porto (IBMC), Porto, Portugal.
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Riddell MR, Winkler-Lowen B, Jiang Y, Davidge ST, Guilbert LJ. Pleiotropic actions of forskolin result in phosphatidylserine exposure in primary trophoblasts. PLoS One 2013; 8:e81273. [PMID: 24339915 PMCID: PMC3855289 DOI: 10.1371/journal.pone.0081273] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 10/10/2013] [Indexed: 11/18/2022] Open
Abstract
Forskolin is an extract of the Coleus forskholii plant that is widely used in cell physiology to raise intracellular cAMP levels. In the field of trophoblast biology, forskolin is one of the primary treatments used to induce trophoblastic cellular fusion. The syncytiotrophoblast (ST) is a continuous multinucleated cell in the human placenta that separates maternal from fetal circulations and can only expand by fusion with its stem cell, the cytotrophoblast (CT). Functional investigation of any aspect of ST physiology requires in vitro differentiation of CT and de novo ST formation, thus selecting the most appropriate differentiation agent for the hypothesis being investigated is necessary as well as addressing potential off-target effects. Previous studies, using forskolin to induce fusion in trophoblastic cell lines, identified phosphatidylserine (PS) externalization to be essential for trophoblast fusion and showed that widespread PS externalization is present even after fusion has been achieved. PS is a membrane phospholipid that is primarily localized to the inner-membrane leaflet. Externalization of PS is a hallmark of early apoptosis and is involved in cellular fusion of myocytes and macrophages. We were interested to examine whether PS externalization was also involved in primary trophoblast fusion. We show widespread PS externalization occurs after 72 hours when fusion was stimulated with forskolin, but not when stimulated with the cell permeant cAMP analog Br-cAMP. Using a forskolin analog, 1,9-dideoxyforskolin, which stimulates membrane transporters but not adenylate cyclase, we found that widespread PS externalization required both increased intracellular cAMP levels and stimulation of membrane transporters. Treatment of primary trophoblasts with Br-cAMP alone did not result in widespread PS externalization despite high levels of cellular fusion. Thus, we concluded that widespread PS externalization is independent of trophoblast fusion and, importantly, provide evidence that the common differentiation agent forskolin has previously unappreciated pleiotropic effects on trophoblastic cells.
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Affiliation(s)
- Meghan R. Riddell
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Bonnie Winkler-Lowen
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Yanyan Jiang
- Department of Obstetrics and Gynecology, University of Alberta, Edmonton, Alberta, Canada
| | - Sandra T. Davidge
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Department of Obstetrics and Gynecology, University of Alberta, Edmonton, Alberta, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
| | - Larry J. Guilbert
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
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Coleman SJ, Gerza L, Jones CJP, Sibley CP, Aplin JD, Heazell AEP. Syncytial nuclear aggregates in normal placenta show increased nuclear condensation, but apoptosis and cytoskeletal redistribution are uncommon. Placenta 2013; 34:449-55. [PMID: 23507147 PMCID: PMC3661987 DOI: 10.1016/j.placenta.2013.02.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 02/19/2013] [Accepted: 02/20/2013] [Indexed: 11/29/2022]
Abstract
Introduction Syncytial nuclear aggregates (SNAs) are increased in pregnancy complications; however, little is known about their origin or function. This study aimed to characterise SNAs in more detail than has been reported previously. Methods Immunohistochemistry and morphological examination at the light and ultrastructural level were used to determine the nature and structure of SNAs. Results SNAs comprising bridges and syncytial knots had similar frequency with 974 per mm3 of villous tissue (IQR 717–1193) and 833 per mm3 (IQR 766–1190), respectively while there were approximately four times as many sectioning artefacts than knots and bridges combined. SNAs had increased proportions of condensed nuclei compared to the remaining syncytiotrophoblast (33.3% vs. 8.9%) and decreased proportions of euchromatic nuclei (0.0% vs. 16.2%), as assessed by examination of an electron micrograph archive. SNAs showed little evidence of apoptosis, with weak positivity for the apoptosis markers M30-neoepitope at 16.6% and TUNEL at 10.0%; strong staining was rarely seen for either marker. Immunofluorescence demonstrated rare association of actin (α, β or γ) with SNAs, whereas tubulin was in close proximity to SNAs and cytokeratin was seen within and surrounding SNAs. Discussion M30-positive SNAs traced through serial sections were significantly more likely to be syncytial knots or sectioning artefacts than bridges. Nuclei within SNAs showed signs consistent with degeneration; however, this is unlikely to be an apoptotic process. There are few changes in configuration of cytoskeletal proteins around SNAs. Conclusions These data suggest that the biogenesis and functional significance of SNAs still require resolution.
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Affiliation(s)
- S J Coleman
- Institute of Human Development, University of Manchester, Maternal and Fetal Health Research Centre, UK.
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11
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Singh AT, Dharmarajan A, Aye ILMH, Keelan JA. Ceramide biosynthesis and metabolism in trophoblast syncytialization. Mol Cell Endocrinol 2012; 362:48-59. [PMID: 22652149 DOI: 10.1016/j.mce.2012.05.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2011] [Revised: 05/02/2012] [Accepted: 05/18/2012] [Indexed: 02/02/2023]
Abstract
Sphingolipid mediators such as ceramide are pleiotropic regulators of cellular growth, differentiation and apoptosis. We investigated the role of ceramide biosynthesis, metabolism and actions in term human cytotrophoblasts syncytialized over 7 days in culture. Intracellular C16 ceramide levels increased modestly after 3 days in culture, then declined. Ceramidase was present at particularly high levels in syncytialized trophoblasts; inhibition of ceramidase reduced the degree of cell fusion. Exposure to short chain C8 ceramide or aSMase enhanced secretion of the differentiation marker hCG without affecting fusion or cell viability. In contrast, pharmacological inhibition of ceramidase reduced the extent of fusion. Inhibition of the ceramide-responsive JNK and PP2A pathways did not abolish the effects of ceramide, and JNK phosphorylation was unresponsive to ceramide; however, ceramide significantly inhibited phosphorylation of Akt. This study suggests that changes in ceramide biosynthesis and metabolism play a differential role in the biochemical and morphological features of trophoblast differentiation.
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Affiliation(s)
- Ambika T Singh
- School of Women's and Infant's Health, Dentistry and Health Sciences, The University of Western Australia, Perth, Australia
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12
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Depoix C, Barret LA, Hubinont C, Debieve F. Viability of primary term cytotrophoblast cell culture in normoxia and hypoxia. Mol Hum Reprod 2012; 19:29-34. [DOI: 10.1093/molehr/gas042] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Riddell MR, Winkler-Lowen B, Guilbert LJ. The contribution of apoptosis-inducing factor (AIF) to villous trophoblast differentiation. Placenta 2011; 33:88-93. [PMID: 22133578 DOI: 10.1016/j.placenta.2011.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 11/14/2011] [Accepted: 11/15/2011] [Indexed: 01/17/2023]
Abstract
Apoptosis is postulated to be a delayed but important part of the differentiation of placental villous cytotrophoblasts (CT) into functional syncytiotrophoblast (ST). This hypothesis is based on the observation that the externalization of phosphatidylserine and the activation of caspase 8 are required for trophoblast differentiation. In contradiction to this hypothesis we have previously found that differentiation occurs in the presence of both broad spectrum and caspase 8 specific inhibitors. Apoptosis-inducing factor (AIF) is a mitochondria-associated protein which is known to translocate to the nucleus and induce caspase-independent nuclear condensation, phosphatidylserine externalization and cell death. Thus AIF nuclear translocation may result in the apoptotic-like features associated with trophoblast differentiation and may be an obligatory event for differentiation to proceed. AIF translocation was assessed in isolated primary trophoblasts by optical section microscopy of antibody stained cells. We found AIF to be strongly expressed in the villous trophoblast and that small amounts of AIF were localized to the nucleus of the cells. Significantly, inhibitors of AIF translocation (calpeptin and zFA-fmk) blocked translocation but not differentiation of the cells. We conclude that AIF translocation is not involved in CT differentiation in isolated cell culture.
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Affiliation(s)
- M R Riddell
- Department of Physiology, 232 HMRC, University of Alberta, Edmonton, Canada
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