title: Segregated Foxc2, NFATc1 and Connexin expression at normal developing venous valves, and Connexin-specific differences in the valve phenotypes of Cx37, Cx43, and Cx47 knockout mice.
abstract: Venous valves (VVs) are critical for unidirectional blood flow from superficial and deep veins towards the heart. Congenital valve aplasia or agenesis may, in some cases, be a direct cause of vascular disease, motivating an understanding of the molecular mechanisms underlying the development and maintenance of VVs. Three gap junction proteins (Connexins), Cx37, Cx43, and Cx47, are specifically expressed at VVs in a highly polarized fashion. VVs are absent from adult mice lacking Cx37; however it is not known if Cx37 is required for the initial formation of valves. In addition, the requirement of Cx43 and Cx47 for VV development has not been studied. Here, we provide a detailed description of Cx37, Cx43, and Cx47 expression during mouse vein development and show by gene knockout that each Cx is necessary for normal valve development. The valve phenotypes in the knockout lines exhibit Cx-specific differences, however, including whether peripheral or central VVs are affected by gene inactivation. In addition, we show that a Cx47 null mutation impairs peripheral VV development but does not affect lymphatic valve formation, a finding of significance for understanding how some CX47 mutations cause inherited lymphedema in humans. Finally, we demonstrate a striking segregation of Foxc2 and NFATc1 transcription factor expression between the downstream and upstream faces, respectively, of developing VV leaflets and show that this segregation is closely associated with the highly polarized expression of Cx37, Cx43, and Cx47. The partition of Foxc2 and NFATc1 expression at VV leaflets makes it unlikely that these factors directly cooperate during the leaflet elongation stage of VV development.
authors.affiliation: Department of Physiology, University of Arizona, Tucson, AZ 85724, USA. Electronic address: sjmunger@email.arizona.edu.
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: Munger
authors.affiliation: Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA. Electronic address: Xin-geng@omrf.org.
authors.forename: Xin
authors.initials: X
authors.lastname: Geng
authors.affiliation: Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA. Electronic address: Sathish-Srinivasan@omrf.org.
authors.forename: R Sathish
authors.initials: RS
authors.lastname: Srinivasan
authors.affiliation: Department of Surgery, University of Arizona, Tucson, AZ 85724, USA. Electronic address: grace@surgery.arizona.edu.
authors.forename: Marlys H
authors.initials: MH
authors.lastname: Witte
authors.affiliation: Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA. Electronic address: dpaul@hms.harvard.edu.
authors.forename: David L
authors.initials: DL
authors.lastname: Paul
authors.affiliation: Department of Physiology, University of Arizona, Tucson, AZ 85724, USA. Electronic address: amsimon@email.arizona.edu.
authors.forename: Alexander M
authors.initials: AM
authors.lastname: Simon
mesh_terms: D000818:Animals; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism*; D017630:Connexins / Q000235:genetics / Q000378:metabolism*; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D050778:NFATC Transcription Factors / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D013997:Time Factors; D055422:Venous Valves / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D000097006:Gap Junction alpha-4 Protein
chemical_list: D018031:Connexin 43; D017630:Connexins; D051858:Forkhead Transcription Factors; D050778:NFATC Transcription Factors; D000097006:Gap Junction alpha-4 Protein; C427305:connexin 47; C082078:mesenchyme fork head 1 protein
keywords: Chronic venous disease; Connexin; Foxc2; Lymphedema; NFATc1; Valve development