LGL1 modulates proliferation, apoptosis, and migration of human fetal lung flbroblasts

摘要

Rapid growth and formation of new gas exchange units (alveogenesis) are hallmarks of the perinatal lung. Bronchopulmonary dysplasia (BPD), common in very premature infants, is characterized by premature arrest of alveogenesis. Mesenchymal cells (fibroblasts) regulate both lung branching and alveogenesis through mesenchymal-epithelial interactions. Temporal or spatial deficiency of late-gestation lung 1/cysteine-rich secretory protein LD2 (LGL1/CRISPLD2), expressed in and secreted by lung fibroblasts, can impair both lung branching and alveogenesis (LGL1 denotes late gestation lung 1 protein; LGLI denotes the human gene; Lgll denotes the mouse/rat gene). Absence of Lgll is embryonic lethal. Lgll levels are dramatically reduced in oxygen toxicity rat models of BPD, and heterozygous Lgll+I~~ mice exhibit features resembling human BPD. To explore the role of LGLI in mesenchymal-epithelial interactions in developing lung, we developed a doxy-cycline (DOX)-inducible RNA-mediated LGLI knockdown cellular model in human fetal lung fibroblasts (MRC5LGL1KD). We assessed the impact of LGLI on cell proliferation, cell migration, apoptosis, and wound healing. DOX-induced MRC5LGL1KD suppressed cell growth and increased apoptosis of annexin V+ staining cells and caspase 3/7 activity. LGLI-conditioned medium increased migration of fetal rat primary lung epithelial cells and human airway epithelial cells. Impaired healing by MRC5LGL1KD cells of a wound model was attenuated by addition of LGLI-conditioned medium. Suppression of LGLI was associated with dysregulation of extracellular matrix genes (downregulated MMP1, ColXVal, and ELASTIN) and proapoptosis genes (upregulated BAD, BAK, CASP2, and TNFRSF1B) and inhibition of 44/42MAPK phosphorylation. Our findings define a role for LGLI in fibroblast expansion and migration, epithelial cell migration, and mesenchymal-epithelial signaling, key processes in fetal lung development.