Abstract
Bronchopulmonary dysplasia (BPD) is a common complication of premature birth and is modeled in rodents by exposure of newborns to 85% O2. Perturbations to extracellular matrix (ECM) production and remodeling play a causal role in arrested lung development associated with BPD. An unbiased microarray screen of microRNA (miR) abundance in the developing lung revealed miR-29c-3p, which targets ECM components (elastin and collagens), to be deregulated in experimental BPD. Changes in miR-29c expression were validated by real-time RT-PCR, where miR-29c was significantly (up to four-fold) increased in developing mouse lungs in response to hyperoxia exposure. Further in vitro studies in primary lung fibroblasts validated both eln mRNA (encoding tropoelastin), and mRNA encoding col4a1 and col4a5 and other basement membrane collagens, as well as fbn1 (fibulin 1) as targets of miR-29c-3p. Treatment of newborn mouse pups with an antagomiR-29c-3p, which blocks miR-29c-3p function in vivo, resulted in a partial protection against the damaging effects of hyperoxia on lung structural development. Notably, hyperoxia drove increased septal wall thickness, and antagomiR-29c application concomitantly with hyperoxia protected against any increase in septal wall thickness, which remained normal (10.00 μm). Biochemical and histological analyses further revealed that antagomiR-29c application drove increased insoluble elastin protein abundance, and partially normalized the deposition of elastin into foci at the tips of developing septa, in the lungs of newborn mice exposed to hyperoxia. These data identify miR-29c as a causal factor in the arrest alveolarization seen in experimental BPD.
- Copyright ©the authors 2016