title: Placental development during early pregnancy in sheep: cell proliferation, global methylation, and angiogenesis in the fetal placenta.
abstract: To characterize early fetal placental development, gravid uterine tissues were collected from pregnant ewes every other day from day 16 to 30 after mating. Determination of 1) cell proliferation was based on Ki67 protein immunodetection; 2) global methylation was based on 5-methyl-cytosine (5mC) expression and mRNA expression for DNA methyltransferases (DNMTs) 1, 3a, and 3b; and 3) vascular development was based on smooth muscle cell actin immunolocalization and on mRNA expression of several factors involved in the regulation of angiogenesis in fetal membranes (FMs). Throughout early pregnancy, the labeling index (proportion of proliferating cells) was very high (21%) and did not change. Expression of 5mC and mRNA for DNMT3b decreased, but mRNA for DNMT1 and 3a increased. Blood vessels were detected in FM on days 18-30 of pregnancy, and their number per tissue area did not change. The patterns of mRNA expression for placental growth factor, vascular endothelial growth factor, and their receptors FLT1 and KDR; angiopoietins 1 and 2 and their receptor TEK; endothelial nitric oxide synthase and the NO receptor GUCY13B; and hypoxia inducing factor 1 α changed in FM during early pregnancy. These data demonstrate high cellular proliferation rates, and changes in global methylation and mRNA expression of factors involved in the regulation of DNA methylation and angiogenesis in FM during early pregnancy. This description of cellular and molecular changes in FM during early pregnancy will provide the foundation for determining the basis of altered placental development in pregnancies compromised by environmental, genetic, or other factors.
authors.affiliation: Department of Animal Sciences, Center for Nutrition and Pregnancy, North Dakota State University, Fargo, North Dakota 58108, USA. anna.grazul-bilska@ndsu.edu
authors.forename: Anna T
authors.initials: AT
authors.lastname: Grazul-Bilska
authors.forename: Mary Lynn
authors.initials: ML
authors.lastname: Johnson
authors.forename: Pawel P
authors.initials: PP
authors.lastname: Borowicz
authors.forename: Megan
authors.initials: M
authors.lastname: Minten
authors.forename: Jerzy J
authors.initials: JJ
authors.lastname: Bilski
authors.forename: Robert
authors.initials: R
authors.lastname: Wroblewski
authors.forename: Mila
authors.initials: M
authors.lastname: Velimirovich
authors.forename: Lindsey R
authors.initials: LR
authors.lastname: Coupe
authors.forename: Dale A
authors.initials: DA
authors.lastname: Redmer
authors.forename: Lawrence P
authors.initials: LP
authors.lastname: Reynolds
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D019175:DNA Methylation / Q000502:physiology; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000235:genetics / Q000378:metabolism; D005865:Gestational Age; D018919:Neovascularization, Physiologic / Q000235:genetics / Q000502:physiology; D010920:Placenta / Q000098:blood supply* / Q000378:metabolism*; D010929:Placentation; D011247:Pregnancy; D011270:Pregnancy, Animal; D012756:Sheep / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D013997:Time Factors; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism
chemical_list: D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2