LSC 2013 abstract - miRNA-based identification of SEC14L3 deregulation in murine experimental asthma

Background: MicroRNAs are small non-coding RNAs essential for immune function and lung development. Previously, we had found increased pulmonary expression of miR-17, -144 & miR-21, correlating with decreased mRNA & protein levels of the putative targets CREB1 and its co-activators CRTC 1&3 in mice with ova-induced asthma. Expressions were modulated by in vitro overexpression/silencing of the miRNAs. We now hypothesized that miR-17, -144 &-21 regulate CREB1/CRTC-mediated gene transcription in experimental asthma and sought to identify new targets of relevance for asthma. Methods: Murine lung epithelial cells (MLE-12) or human bronchial epithelial cells (16-HBE) were transfected with precursor miRNAs/antimiRs. Expression of miRNAs/targets was evaluated by RT-qPCR and Western blotting. For selection of CREB1 targets down-regulated genes in lungs of mice with ova-induced asthma were screened for CRE elements in their promoter region. Lung sections were histologically assessed by periodic acid schiff (PAS) stain and SEC14L3 immunostaining. Results: Among the 35 candidate CREB1 targets we chose SEC14L3 & LTBP4 as both were already brought into context with asthma. Their mRNA expressions were influenced by in vitro overexpression/ silencing of the candidate miRNAs in a CREB1-dependent manner. For SEC14L3 we confirmed this in vivo deregulation on protein level by western blot and immunostainings of lung sections, where it coincided with goblet cell metaplasia. Conclusion: Using miRNA profiles as preselection tools, we identified SEC14L3 as new target that might be useful for monitoring the integrity of the respiratory epithelium in experimental asthma.