Caveolin-1 Deficiency Induces Spontaneous Endothelial-to-Mesenchymal Transition in Murine Pulmonary Endothelial Cells in Vitro

It was previously demonstrated that transforming growth factor beta (TGF-beta) induces endothelial-to-mesenchymal transition (EndoMT) in murine Lung endothelial cells (ECs) in vitro. Owing to the important role of caveolin-1 (CAV1) in TGF-beta receptor internalization and TGF-beta signaling, the participation of CAV1 in the induction of EndoMT in murine lung ECs was investigated. Pulmonary ECs were isolated from wild-type and Cav1 knockout mice using immunomagnetic methods with sequential anti-CD31 and anti-CD102 antibody selection followed by in vitro culture and treatment with TGF-beta 1. EndoMT was assessed by semiquantitative RT-PCR for Acta2, Col1a1, Snai1, and Snai2; by immunofluorescence for alpha-smooth muscle actin; and by Western blot analysis for alpha-smooth muscle actin, SNAIL1, SNAIL2, and the alpha 2 chain of type I collagen. The same studies were performed in Cav1(-/-) pulmonary ECs after restoration of functional CAV1 domains using a cell-permeable CAV1 scaffolding domain peptide. Pulmonary ECs from Cav1 knockout mice displayed high Levels of spontaneous Acta2, Col1A, Snai1, and Snai2 expression, which increased after TGF-beta treatment. Spontaneous and TGF-beta 1-stimulated EndoMT were abrogated by the restoration of functional CAV1 domains using a cell-permeable peptide. The findings suggest that CAV1 regulation of EndoMT may play a role in the development of fibroproliferative vasculopathies. (Am J Pathol 2013, 182: 325-331; http://dx.doi.org/10.1016/j.ajpath.2012.10.022)