title: Activin receptor-like kinase 1 is essential for placental vascular development in mice.
abstract: Activin receptor-like kinase 1 (ALK1) is involved in the pathogenesis of hereditary hemorrhagic telangiectasia type II (HHT2) and pulmonary arterial hypertension. We have previously shown that Alk1 is predominantly expressed in the arterial endothelium and plays a pivotal role in the formation of embryonic blood vessels. At present, however, little is known about the precise expression pattern and function of ALK1 during extra-embryonic vascular development. Using previously generated lacZ reporter lines, we sought to examine the expression pattern and role of Alk1 during placental development in mice. Alk1 expression was restricted to endothelial cells of fetal vessels from the emergence of chorioallantoic fusion to the late gestational period, and no detectable Alk1 expression was observed in syncytiotrophoblasts or spongiotrophoblasts. Predominant arterial expression was observed in the umbilical and fetal placental vessels as well as in embryonic vessels. Morphological analysis of Alk1-null embryos indicates that Alk1 is essential for the development of distinct umbilical arteries and veins. The invasion of chorioallantoic mesoderm into the forming labyrinth layer was largely unaffected in the Alk1-null placenta, but chorioallantoic vessels appeared to be severely dilated and fused. Results from this study provide valuable information regarding the role of ALK1 in the development of placental vasculature as well as insights into the pathogenesis of HHT.
authors.affiliation: Department of Physiology and Functional Genomics, University of Florida College of Medicine, Shands Cancer Center, Gainesville, FL 32610, USA.
authors.forename: Kwon-Ho
authors.initials: KH
authors.lastname: Hong
authors.forename: Tsugio
authors.initials: T
authors.lastname: Seki
authors.forename: S Paul
authors.initials: SP
authors.lastname: Oh
mesh_terms: D030201:Activin Receptors, Type I / Q000378:metabolism*; D000818:Animals; D001158:Arteries / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000201:enzymology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D017930:Genes, Reporter; D007150:Immunohistochemistry; D007763:Lac Operon; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D018919:Neovascularization, Physiologic; D010920:Placenta / Q000098:blood supply*; D010929:Placentation / Q000502:physiology*; D011247:Pregnancy; D013683:Telangiectasia, Hereditary Hemorrhagic / Q000201:enzymology* / Q000473:pathology
chemical_list: D030201:Activin Receptors, Type I