title: Notch signaling functions in lymphatic valve formation.
abstract: Collecting lymphatic ducts contain intraluminal valves that prevent backflow. In mice, lymphatic valve morphogenesis begins at embryonic day 15.5 (E15.5). In the mesentery, Prox1 expression is high in valve-forming lymphatic endothelial cells, whereas cells of the lymphatic ducts express lower levels of Prox1. Integrin α9, fibronectin EIIIA, Foxc2, calcineurin and the gap junction protein Cx37 are required for lymphatic valve formation. We show that Notch1 is expressed throughout the developing mesenteric lymphatic vessels at E16.5, and that, by E18.5, Notch1 expression becomes highly enriched in the lymphatic valve endothelial cells. Using a Notch reporter mouse, Notch activity was detected in lymphatic valves at E17.5 and E18.5. The role of Notch in lymphatic valve morphogenesis was studied using a conditional lymphatic endothelial cell driver either to delete Notch1 or to express a dominant-negative Mastermind-like (DNMAML) transgene. Deletion of Notch1 led to an expansion of Prox1(high) cells, a defect in Prox1(high) cell reorientation and a decrease in integrin α9 expression at sites of valve formation. Expression of DNMAML, which blocks all Notch signaling, resulted in a more severe phenotype characterized by a decrease in valves, failure of Prox1(high) cells to cluster, and rounding of the nuclei and decreased fibronectin-EIIIA expression in the Prox1(high) cells found at valve sites. In human dermal lymphatic endothelial cells, activation of Notch1 or Notch4 induced integrin α9, fibronectin EIIIA and Cx37 expression. We conclude that Notch signaling is required for proper lymphatic valve formation and regulates integrin α9 and fibronectin EIIIA expression during valve morphogenesis.
authors.affiliation: Department of OB/GYN, Columbia University Medical Center, New York, NY 10032, USA Division of Genetics, Department of Biosciences, Viikki Biocenter, University of Helsinki, POB 56, Helsinki FIN-00014, Finland.
authors.forename: Aino
authors.initials: A
authors.lastname: Murtomaki
authors.affiliation: Department of OB/GYN, Columbia University Medical Center, New York, NY 10032, USA Department of Pharmacology, Columbia University Medical Center, New York, NY 10032, USA.
authors.forename: Minji K
authors.initials: MK
authors.lastname: Uh
authors.affiliation: Department of OB/GYN, Columbia University Medical Center, New York, NY 10032, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Kitajewski
authors.affiliation: Department of Ophthalmology, Columbia University Medical Center, New York, NY 10032, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Ophthalmology, Columbia University Medical Center, New York, NY 10032, USA.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nagasaki
authors.affiliation: Department of OB/GYN, Columbia University Medical Center, New York, NY 10032, USA.
authors.forename: Carrie J
authors.initials: CJ
authors.lastname: Shawber
authors.affiliation: Department of OB/GYN, Columbia University Medical Center, New York, NY 10032, USA Department of Pathology, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY 10032, USA jkk9@cumc.columbia.edu.
authors.forename: Jan
authors.initials: J
authors.lastname: Kitajewski
mesh_terms: D000818:Animals; D019070:Cell Lineage; D002478:Cells, Cultured; D017630:Connexins / Q000378:metabolism; D020405:Dermis / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D017353:Gene Deletion; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D005799:Genes, Dominant; D006801:Humans; D039001:Integrin alpha Chains / Q000378:metabolism; D042601:Lymphatic Vessels / Q000196:embryology* / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D051881:Receptor, Notch1 / Q000378:metabolism / Q000502:physiology*; D000074562:Receptor, Notch4; D051880:Receptors, Notch / Q000502:physiology*; D015398:Signal Transduction; D019076:Transgenes; D000097006:Gap Junction alpha-4 Protein
chemical_list: D017630:Connexins; D005353:Fibronectins; D039001:Integrin alpha Chains; D011518:Proto-Oncogene Proteins; D051881:Receptor, Notch1; D000074562:Receptor, Notch4; D051880:Receptors, Notch; D000097006:Gap Junction alpha-4 Protein; C497761:NOTCH1 protein, human; C106075:NOTCH4 protein, human; C497762:Notch1 protein, mouse; C572454:extra domain A fibronectin, mouse; C084613:integrin alpha9; C073572:Notch4 protein, mouse
keywords: Integrin α9; Lymphatic valve morphogenesis; Mouse; Notch