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Monson T, Wright T, Galan HL, Reynolds PR, Arroyo JA. Caspase dependent and independent mechanisms of apoptosis across gestation in a sheep model of placental insufficiency and intrauterine growth restriction. Apoptosis 2017; 22:710-718. [DOI: 10.1007/s10495-017-1343-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Huang Q, Chen H, Wang F, Brost BC, Li J, Gao Y, Li Z, Gao Y, Jiang SW. Reduced syncytin-1 expression in choriocarcinoma BeWo cells activates the calpain1-AIF-mediated apoptosis, implication for preeclampsia. Cell Mol Life Sci 2014; 71:3151-64. [PMID: 24413738 PMCID: PMC4644425 DOI: 10.1007/s00018-013-1533-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 11/02/2013] [Accepted: 11/21/2013] [Indexed: 12/15/2022]
Abstract
Placentas associated with preeclampsia are characterized by extensive apoptosis in trophoblast lineages. Syncytin-1 (HERVWE1) mediates the fusion of cytotrophoblasts to form syncytiotrophoblasts, which assume the placental barrier, fetal-maternal exchange and endocrine functions. While decreased syncytin-1 expression has been observed in preeclamptic placentas, it is not clear if this alteration is involved in trophoblast apoptosis. In the current study, we found that siRNA-mediated knockdown of syncytin-1 led to apoptosis in choriocarcinoma BeWo, a cell line of trophoblastic origin. Characterization of the apoptotic pathways indicated that this effect does not rely on the activation of caspases. Rather, decreased syncytin-1 levels activated the apoptosis inducing factor (AIF) apoptotic pathway by inducing the expression, cleavage, and nuclear translocation of AIF. Moreover, calpain1, the cysteine protease capable of cleaving AIF, was upregulated by syncytin-1 knockdown. Furthermore, treatment with calpain1 inhibitor MDL28170 effectively reversed AIF cleavage, AIF nuclear translocation, and cell apoptosis triggered by syncytin-1 downregulation, verifying the specific action of calpain1-AIF pathway in trophoblast apoptosis. We confirmed that preeclamptic placentas express lower levels of syncytin-1 than normal placentas, and observed an inverse correlation between syncytin-1 and AIF/calpain1 mRNA levels, a result consistent with the in vitro findings. Immunohistochemistry analyses indicated decreased syncytin-1 and increased AIF and calpain1 protein levels in apoptotic cells of preeclamptic placentas. These findings have for the first time revealed that decreased levels of syncytin-1 can trigger the AIF-mediated apoptosis pathway in BeWo cells. This novel mechanism may contribute to the structural and functional deficiencies of syncytium frequently observed in preeclamptic placentas.
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Affiliation(s)
- Qiang Huang
- The Second Affiliated Hospital, Xi’an Jiaotong University School of Medicine, Xi’an, 710004 Shaanxi China
- Department of Biological Science, Mercer University School of Medicine, Savannah, GA 31404 USA
| | - Haibin Chen
- Department of Histology and Embryology, Shantou University Medical College, Shantou, 515041 Guangzhou China
| | - Fengchao Wang
- National Institute of Biological Sciences (NIBS), Beijing, 102206 China
| | - Brian C. Brost
- Department of Obstetrics and Gynecology, Mayo Clinic, Mayo College of Medicine, Rochester, MN 55902 USA
| | - Jinping Li
- Department of Biological Science, Mercer University School of Medicine, Savannah, GA 31404 USA
- Department of Obstetrics and Gynecology, Mayo Clinic, Mayo College of Medicine, Rochester, MN 55902 USA
| | - Yu Gao
- Department of Obstetrics and Gynecology, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080 China
| | - Zongfang Li
- The Second Affiliated Hospital, Xi’an Jiaotong University School of Medicine, Xi’an, 710004 Shaanxi China
| | - Ya Gao
- The Second Affiliated Hospital, Xi’an Jiaotong University School of Medicine, Xi’an, 710004 Shaanxi China
| | - Shi-Wen Jiang
- Department of Biological Science, Mercer University School of Medicine, Savannah, GA 31404 USA
- Department of Obstetrics and Gynecology, Mayo Clinic, Mayo College of Medicine, Rochester, MN 55902 USA
- Department of Obstetrics and Gynecology, Memorial Health University Medical Center, Savannah, GA 31404 USA
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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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