Aspects of caveolin expression in alveolar epithelial cells after injury

Alveolar epithelial cell apoptosis/necrosis is a critical event during remodeling processes in bleomycin-induced pulmonary fibrosis. Using a new epithelial type I cell-like R3/1 cell line derived from fetal rat lung, we studied the expression of caveolin-1 under conditions of bleomycin-induced injury in vitro.

The assessment of Triton X-100 solubility revealed that caveolin-1 was largely abundant in detergent-resistent membrane fractions. This is consistent with the localization of caveolin-1 in the lipid rafts/caveolae. Using sucrose gradient centrifugation we demonstrated that the majority of caveolin-1 is present in lipid rafts. Triton solubility assessment of membranes from bleomycin-treated cells revealed no differences in the caveolin-1 distribution to controls. The major interesting outcome of our study is the dissociation of caveolin-1 from the lipid raft/caveolae fractions to the non-caveolar fractions after bleomycin treatment indicating an intracellular retention of caveolin-1. This result suggests the possibility that the translocation of caveolin-1 could be an important event regulating the metabolism of alveolar epithelial lung cells after injury.