title: HoxA5 stabilizes adherens junctions via increased Akt1.
abstract: Normal vascular development and angiogenesis is regulated by coordinated changes in cell-cell and cell-extracellular matrix (ECM) interactions. The Homeobox (Hox) family of transcription factors coordinately regulate expression of matrix degrading proteinases, integrins and ECM components and profoundly impact vascular remodeling. Whereas HoxA5 is down regulated in active angiogenic endothelial cells (EC), sustained expression of HoxA5 induces TSP-2 and blocks angiogenesis. Since HoxA5 is also lacking in EC in proliferating hemangiomas, we investigated whether restoring expression of HoxA5 could normalize hemangioma cell morphology and/or behavior. Sustained expression of HoxA5 in the murine hemangioma cell line (EOMA) reduced their growth in vivo and promoted branching morphogenesis in 3D BM cultures. Moreover, restoring HoxA5 expression increased the retention of beta-catenin in adherens junctions and reduced permeability. In addition we also show that the HoxA5 mediated increase in stability of adherens junctions requires Akt1 activity and introduction of constitutively active myr-Akt in EOMA cells also increased retention of beta-catenin in adherens junctions. Finally we show that HoxA5 increases Akt1 mRNA, protein expression and further enhances Akt activity via a coordinate down regulation of PTEN. Together these results demonstrate a central role for HoxA5 in coordinating a stable vascular phenotype.
authors.affiliation: Department of Surgery, University of California San Francisco, San Francisco, California 94143, USA.
authors.forename: Gemma
authors.initials: G
authors.lastname: Arderiu
authors.forename: Ileana
authors.initials: I
authors.lastname: Cuevas
authors.forename: Amy
authors.initials: A
authors.lastname: Chen
authors.forename: Meritxell
authors.initials: M
authors.lastname: Carrio
authors.forename: Lucy
authors.initials: L
authors.lastname: East
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Boudreau
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism*; D000818:Animals; D045744:Cell Line, Tumor; D042783:Endothelial Cells / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D018398:Homeodomain Proteins / Q000378:metabolism*; D051379:Mice; D018919:Neovascularization, Physiologic / Q000502:physiology*; D051059:PTEN Phosphohydrolase / Q000096:biosynthesis; D010750:Phosphoproteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000096:biosynthesis*; D019699:Thrombospondins; D014157:Transcription Factors; D051176:beta Catenin / Q000378:metabolism; D000099262:Thrombospondin 2
chemical_list: D018398:Homeodomain Proteins; D051059:PTEN Phosphohydrolase; D010750:Phosphoproteins; D051057:Proto-Oncogene Proteins c-akt; D019699:Thrombospondins; D014157:Transcription Factors; D051176:beta Catenin; D000099262:Thrombospondin 2; C059637:Hoxa5 protein, mouse; C514862:Akt1 protein, mouse; C487757:Pten protein, mouse