FOXC2 and fluid shear stress stabilize postnatal lymphatic vasculature
Amélie Sabine, … , Naoyuki Miura, Tatiana V. Petrova
Amélie Sabine, … , Naoyuki Miura, Tatiana V. Petrova
Published September 21, 2015
Citation Information: J Clin Invest. 2015;125(10):3861-3877. https://doi.org/10.1172/JCI80454.
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Research Article Vascular biology

FOXC2 and fluid shear stress stabilize postnatal lymphatic vasculature

Abstract

Biomechanical forces, such as fluid shear stress, govern multiple aspects of endothelial cell biology. In blood vessels, disturbed flow is associated with vascular diseases, such as atherosclerosis, and promotes endothelial cell proliferation and apoptosis. Here, we identified an important role for disturbed flow in lymphatic vessels, in which it cooperates with the transcription factor FOXC2 to ensure lifelong stability of the lymphatic vasculature. In cultured lymphatic endothelial cells, FOXC2 inactivation conferred abnormal shear stress sensing, promoting junction disassembly and entry into the cell cycle. Loss of FOXC2-dependent quiescence was mediated by the Hippo pathway transcriptional coactivator TAZ and, ultimately, led to cell death. In murine models, inducible deletion of Foxc2 within the lymphatic vasculature led to cell-cell junction defects, regression of valves, and focal vascular lumen collapse, which triggered generalized lymphatic vascular dysfunction and lethality. Together, our work describes a fundamental mechanism by which FOXC2 and oscillatory shear stress maintain lymphatic endothelial cell quiescence through intercellular junction and cytoskeleton stabilization and provides an essential link between biomechanical forces and endothelial cell identity that is necessary for postnatal vessel homeostasis. As FOXC2 is mutated in lymphedema-distichiasis syndrome, our data also underscore the role of impaired mechanotransduction in the pathology of this hereditary human disease.

Authors

Amélie Sabine, Esther Bovay, Cansaran Saygili Demir, Wataru Kimura, Muriel Jaquet, Yan Agalarov, Nadine Zangger, Joshua P. Scallan, Werner Graber, Elgin Gulpinar, Brenda R. Kwak, Taija Mäkinen, Inés Martinez-Corral, Sagrario Ortega, Mauro Delorenzi, Friedemann Kiefer, Michael J. Davis, Valentin Djonov, Naoyuki Miura, Tatiana V. Petrova

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Figure 7

FOXC2 is essential for postnatal lymphatic vascular function.

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FOXC2 is essential for postnatal lymphatic vascular function. (A) Time c...
(A) Time course of chylous effusion (pink curve) and lethality (green curve) after Foxc2 inactivation. The dotted line indicates the time point used for most phenotypic analyses. Chylous effusion was defined as the presence of chylothorax or chylous ascites. n = 150 animals (5–20 Foxc2lecKO mice per time point). (B) Macroscopic appearance of chylothorax (top row) and chylous ascites (bottom row) in P8 Foxc2lecKO mice. The arrowheads indicate chyle. (C) Chyle accumulation in the intestinal submucosal lymphatic vessels, in the ceca, and in Peyer’s patches (asterisk) and chyle leakage from mesenteric lymphatic collecting vessels in P8 Foxc2lecKO mice. Black arrowheads indicate chyle accumulation. The white arrow indicates mesenteric vessels. White arrowheads indicate valves. Red arrows indicate chyle leakage. (D) Lymph reflux from the thoracic duct and from dermal collecting lymphatic vessels in P8 Foxc2lecKO mice. Collecting lymphatic vessels were visualized by FITC-dextran injection into the mesenteric lymph node (top row) or the forelimb foot pad (bottom row). Asterisks indicate thoracic ducts. Arrowheads indicate backflow into lymphatic branches. FL, forelimb; LN, axillary lymph node. (E) Impaired lymph transport in Foxc2lecKO Prox1-mOrange2+ pups at P8. FITC-dextran was injected into the inguinal lymph node (asterisks) and visualized in the dermal efferent collecting vessel. Foxc2lecKO animals often showed arrest of the lymph drainage at the site of a misshapen valve with lumen narrowing. Arrowheads indicate valves (see also Supplemental Figure 5). Scale bars: 2 mm (B); 250 μm (C); 1 mm (D); 500 μm (E).