Endocardial cell epithelial-mesenchymal transformation requires Type III TGF¦Â receptor interaction with GIPC

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• 作者：Todd A.  ; Townsend^a ;   ; ^{Todd.Townsend@Vanderbilt.edu} ; Jamille Y.  ; Robinson^a ;   ; ^{Jamille.Robinson@Vanderbilt.edu} ; Tam  ; How^b ;   ; ^c ;   ; ^{How00001@mc.duke.edu} ; Daniel M.  ; DeLaughter^d ;   ; ^{Daniel.M.Delaughter@Vanderbilt.edu} ; Gerard C.  ; Blobe^b ;   ; ^c ;   ; ^{Blobe001@mc.duke.edu} ; Joey V.  ; Barnett^a ;   ; ^{joey.barnett@vanderbilt.edu}
• 关键词：Transforming Growth Factor Beta ; Receptor ; Endothelium ; Transformation ; Valvulogenesis
• 刊名：Cellular Signalling
• 出版年：2012
• 出版时间：January 2012
• 年：2012
• 卷：24
• 期：1
• 页码：247-256
• 全文大小：1228 K

文摘

An early event in heart valve formation is the epithelial-mesenchymal transformation (EMT) of a subpopulation of endothelial cells in specific regions of the heart tube, the endocardial cushions. The Type III TGF¦Â receptor (TGF¦ÂR3) is required for TGF¦Â2- or BMP-2-stimulated EMT in atrioventricular endocardial cushion (AVC) explants in vitro but the mediators downstream of TGF¦ÂR3 are not well described. Using AVC and ventricular explants as an in vitro assay, we found an absolute requirement for specific TGF¦ÂR3 cytoplasmic residues, GAIP-interacting protein, C terminus (GIPC), and specific Activin Receptor-Like Kinases (ALK)s for TGF¦ÂR3-mediated EMT when stimulated by TGF¦Â2 or BMP-2. The introduction of TGF¦ÂR3 into nontransforming ventricular endocardial cells, followed by the addition of either TGF¦Â2 or BMP-2, results in EMT. TGF¦ÂR3 lacking the entire cytoplasmic domain, or only the 3C-terminal amino acids that are required to bind GIPC, fails to support EMT in response to TGF¦Â2 or BMP-2. Overexpression of GIPC in AVC endocardial cells enhanced EMT while siRNA-mediated silencing of GIPC in ventricular cells overexpressing TGF¦ÂR3 significantly inhibited EMT. Targeting of specific ALKs by siRNA revealed that TGF¦ÂR3-mediated EMT requires ALK2 and ALK3, in addition to ALK5, but not ALK4 or ALK6. Taken together, these data identify GIPC, ALK2, ALK3, and ALK5 as signaling components required for TGF¦ÂR3-mediated endothelial cell EMT.