T-cadherin (CDH13, H-cadherin) expression downregulated surfactant proteinD in bronchioloalveolar cells

T cadherin is a unique cadherin cell adhesion molecule that is anchored to the surface membrane through a glycosyl phosphatidyl inositol (GPI) moiety. In the present study, we postulated that T cadherin could regulate surfact ant protein (SP)-D gene expression in human bronchioloalveolar type-II cell s. We transfected A549 cells (human lung cancer cell line with alveolar typ e-II cell characteristics) with the T-cadherin expression vector. Both orig inal and control plasmid-transfected A549 cells expressed SP-D; however, ne ither human nor murine T-cadherin-transfected A549 cells expressed SP-D mRN A. The downregulation of SP-D production in human T-cadherin-expressed A549 cells was also demonstrated using Western immunoblotting techniques. Contr ol vector-transfected A549 cells showed a positive band of SP-D but not of T cadherin. In contrast, T-cadherin-transfected A549 cells, which expressed T-cadherin protein, did not produce SP-D. We further examined the relation ship of T cadherin and SP-D expression in secondary pulmonary alveolar prot einosis associated with hematolymphoid malignancies. SP-D was detected in b ronchioloalveolar type-II cells in alveolar proteinosis. However, little or no T-cadherin expression was detected in alveolar type-II cells in these p atients. To our knowledge, this is the first report describing an effect of cadherin on SP production in bronchioloalveolar cells.