Pulmonary hypoplasia in the connective tissue growth factor (Ctgf) null mouse

Abstract

Connective tissue growth factor (CTGF) is a mediator of growth factor activity, and Ctgf knockouts die at birth from respiratory failure due to skeletal dysplasia. Previous microarray analysis revealed Ctgf downregulation in the hypoplastic lungs of amyogenic mouse embryos. This study, therefore, examined pulmonary development in Ctgf-/- mouse fetuses to investigate if respiration could also have been impaired by lung abnormalities. The Ctgf-/- lungs were hypoplastic, with reduced cell proliferation and increased apoptosis. PDGF-B, its receptor and IGF-I, were markedly attenuated and the TTF-1 gradient lost. Type II pneumocyte differentiation was perturbed, the cells depicting excessive glycogen retention and diminished lamellar body and nuclear size, though able to synthesize surfactant-associated protein. However, type I pneumocyte differentiation was not affected by Ctgf deletion. Our findings indicate that the absence of Ctgf and/or its protein product, CTGF, may induce pulmonary hypoplasia by both disrupting basic lung developmental processes and restricting thoracic expansion. © 2008 Wiley-Liss, Inc.