| 1. |
- Bazigou, Eleni, et al.
(författare)
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Integrin-alpha9 is required for fibronectin matrix assembly during lymphatic valve morphogenesis.
- 2009
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Ingår i: Developmental Cell. - : Elsevier BV. - 1534-5807 .- 1878-1551. ; 17:2
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Tidskriftsartikel (refereegranskat)abstract
- Dysfunction of lymphatic valves underlies human lymphedema, yet the process of valve morphogenesis is poorly understood. Here, we show that during embryogenesis, lymphatic valve leaflet formation is initiated by upregulation of integrin-alpha9 expression and deposition of its ligand fibronectin-EIIIA (FN-EIIIA) in the extracellular matrix. Endothelial cell-specific deletion of Itga9 (encoding integrin-alpha9) in mouse embryos results in the development of rudimentary valve leaflets characterized by disorganized FN matrix, short cusps, and retrograde lymphatic flow. Similar morphological and functional defects are observed in mice lacking the EIIIA domain of FN. Mechanistically, we demonstrate that in primary human lymphatic endothelial cells, the integrin-alpha9-EIIIA interaction directly regulates FN fibril assembly, which is essential for the formation of the extracellular matrix core of valve leaflets. Our findings reveal an important role for integrin-alpha9 signaling during lymphatic valve morphogenesis and implicate it as a candidate gene for primary lymphedema caused by valve defects.
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| 2. |
- Lutter, Sophie, et al.
(författare)
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Smooth muscle-endothelial cell communication activates Reelin signaling and regulates lymphatic vessel formation.
- 2012
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Ingår i: Journal of Cell Biology. - : Rockefeller University Press. - 0021-9525 .- 1540-8140. ; 197:6
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Tidskriftsartikel (refereegranskat)abstract
- Active lymph transport relies on smooth muscle cell (SMC) contractions around collecting lymphatic vessels, yet regulation of lymphatic vessel wall assembly and lymphatic pumping are poorly understood. Here, we identify Reelin, an extracellular matrix glycoprotein previously implicated in central nervous system development, as an important regulator of lymphatic vascular development. Reelin-deficient mice showed abnormal collecting lymphatic vessels, characterized by a reduced number of SMCs, abnormal expression of lymphatic capillary marker lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), and impaired function. Furthermore, we show that SMC recruitment to lymphatic vessels stimulated release and proteolytic processing of endothelium-derived Reelin. Lymphatic endothelial cells in turn responded to Reelin by up-regulating monocyte chemotactic protein 1 (MCP1) expression, which suggests an autocrine mechanism for Reelin-mediated control of endothelial factor expression upstream of SMC recruitment. These results uncover a mechanism by which Reelin signaling is activated by communication between the two cell types of the collecting lymphatic vessels--smooth muscle and endothelial cells--and highlight a hitherto unrecognized and important function for SMCs in lymphatic vessel morphogenesis and function.
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