The role of TGF-・・signaling in Angiogenesis

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In order to elucidate molecular mechanisms by which TGF-β/ALK5/Smad2/3 pathway regulates vascular development, we established mouse embryonic endothelial cells (MEECs) from Smad2/3 conditionally inactivated mice. When we checked the reaction against for the shear stress, the Smad2/3KO MEECs did not respond it. Then we analyzed the molecular mechanisms with mRNA and miRNA arrays analysis and found that the expression of some cadherins were reduced in Smad2/3 KO MEEC compared to the wild type MEECs.Although TGF-β signaling is known to play key roles in angiogenesis, it remains veiled how TGF-β regulates lymphangiogenesis. To elucidate molecular mechanisms by which TGF-β pathway controls lymphatic vascular development, we conditionally inactivated TGF-β type II receptor (TβRII) in LECs using Prox1-Cre-ER transgenic mice. When we administered Tamoxifen (TM) at E10.5 and E11.5, TβRIIF/F ; Prox1-CreER embryos showed edema at E14.5. Therefore we stained blood and lymphatic vessels with anti-PECAM-1 and anti-LYVE-1 antibodies, respectively. Interestingly, blood vessel seemed to be well-established, whereas lymphatic vessels merely existed though they were ragged and poorly organized. These data indicated that TGF-β signaling is indispensable for maintenance of lymphatic vessel integrities.