Developmental Decline in Mir-199a-3p and Mir-214 in Human Fetal Lung Promotes Type II Cell Differentiation By Upregulation of Key Transcriptional Regulators
Presentation Number: OR17-6
Date of Presentation: April 2nd, 2017
Ritu Mishra*1, Wei Guo2, Houda Benlhabib2 and Carole R Mendelson3
1University of Texas Southwestern Medical center, Dallas, TX, 2University of Texas Southwestern Med Ctr, Dallas, TX, 3UT Southwestern Medical Center
Surfactant protein-A (SP-A), the major protein of pulmonary surfactant, is developmentally regulated in fetal lung and is produced by differentiated alveolar type II cells. SP-A expression and type II cell differentiation in human fetal lung (HFL) is upregulated by hormones and factors (e.g. prostaglandins) that increase cAMP and is dependent upon a critical oxygen tension. cAMP induction of SP-A gene transcription in HFL is mediated by increased binding of Nkx2.1/TTF-1 and NF-κB to a critical response element in the SP-A promoter, and is associated with permissive epigenetic changes. To study the role of microRNAs (miRNAs, miRs) in type II cell differentiation and developmental induction of SP-A expression, we performed miRNA microarray analysis of RNA from epithelial cells isolated from HFL explants before culture and after 48 and 96 h of culture ± Bt2cAMP. Among the differentially expressed miRNAs in the array, we observed that hsa-miR-199a-3p and hsa-miR-214 were most profoundly decreased upon cAMP-induction of type II cell differentiation. Some of the known and predicted targets of hsa-miR-199a-3p and hsa-miR-214 include cyclooxygenase 2 (COX-2), inhibitor of NF-κB kinase b (IKKβ), CREB, CCAAT enhancer binding proteins (C/EBP) C/EBP-α and C/EBP-β. COX-2, NF-kB and C/EBP family members were previously found to mediate stimulation of SP-A expression in HFL, while Creb1 KO studies in mice, suggest its role in type I and type II cell differentiation. Accordingly, overexpression of miR-199a-3p or miR-214 in cultured HFL type II cells decreased protein levels of IKKβ, CREB, C/EBP-α, C/EBP-β and COX-2 with an associated marked inhibition of SP-A expression. Collectively, these findings suggest that the developmental decline in miR-199a-3p and miR-214 expression in HFL causes increased expression of critical targets that enhance SP-A expression and alveolar type II cell differentiation.
Nothing to Disclose: RM, WG, HB, CRM