Integrin linked kinase regulates syncytialization of BeWo trophoblast cells.
During placental development, mononuclear villous cytotrophoblast cells differentiate and fuse with the overlying syncytiotrophoblast. This process requires the dissolution of E-cadherin (CDH1)-containing adherens junctions in cytotrophoblast. Integrin linked kinase (ILK) can downregulate CDH1 through poly (ADP-ribose) polymerase 1 (PARP1) and Snail-1 (SNAI1) during epithelial-mesenchymal transition. ILK is known to be expressed in cytotrophoblast; thus, the role of a potential ILK-PARP1-SNAI1 pathway in aiding trophoblast syncytialization via the downregulation of CDH1 was examined. The spatiotemporal expression of PARP1, SNAI1, and CDH1 were determined in first and early second trimester chorionic villi, term villi, and BeWo cells by immunofluorescence analysis. PARP1 and SNAI1 were highly detectable in villous cytotrophoblast nuclei of human chorionic villi and SNAI1 expression, in particular, also persisted in syncytiotrophoblast. In BeWo cells undergoing syncytialization, PARP1 and SNAI1 increasingly localized to cell nuclei in correlation with decreased CDH1 expression. Using luciferase reporter assays, it was determined that PARP1 and SNAI1 promoter activities were significantly higher in BeWo cells during syncytialization compared to the activities in proliferating cells. Overexpression of wild type or constitutively active ILK also resulted in significantly increased PARP1 and SNAI1 promoter activities while dominant negative ILK overexpression significantly reduced promoter activities. Lastly, siRNA-mediated depletion of ILK expression in BeWo cells undergoing syncytialization resulted in significantly reduced SNAI1 expression and a significant reduction in the incidence of syncytialization correlating with increased CDH1 expression. These results demonstrate that ILK aids trophoblast syncytialization via the downregulation of CDH1, perhaps through an ILK-PARP1-SNAI1 pathway.
Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, Newfoundland and Labrador Canada.
Trina M
TM
Butler
Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Justin A
JA
Pater
Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, Newfoundland and Labrador Canada.|Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.|One Reproductive Health Research Group, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Daniel J
DJ
MacPhee
D015703:Antigens, CD; D015820:Cadherins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002824:Chorionic Villi / Q000378:metabolism*; D005260:Female; D006801:Humans; D000071137:Poly (ADP-Ribose) Polymerase-1 / Q000378:metabolism*; D011247:Pregnancy; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D000071250:Snail Family Transcription Factors / Q000378:metabolism*; D014327:Trophoblasts / Q000378:metabolism*; D000099200:Scaffold Protein ILK
D015703:Antigens, CD; D015820:Cadherins; D000071137:Poly (ADP-Ribose) Polymerase-1; D017346:Protein Serine-Threonine Kinases; D000071250:Snail Family Transcription Factors; D000099200:Scaffold Protein ILK; C513384:CDH1 protein, human; C000604407:SNAI1 protein, human; C499320:PARP1 protein, human
Snail; integrin-linked kinase; placenta; poly (ADP) ribose polymerase; trophoblast