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Transcriptome Effects of the knockout of Intraflagellar Transport 88 gene in mice Mitral leaflets

ABSTRACT: Transcriptome Effects of the knockout of Intraflagellar Transport 88 gene in mice Mitral leaflets

PROVIDER: PRJNA419804 | ENA |

REPOSITORIES: ENA

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Project description:Rational: We previously reported evidence of endothelial to mesenchymal transition (EndMT) and fibrosis in mitral valve (MV) leaflets at two to six months post-myocardial infarction (MI) in sheep. The onset of these changes and the mechanism of their instigation are not known. Early modulation of EndMT and fibrosis in MV leaflets may limit the development of ischemic mitral regurgitation (IMR) and heart failure. H Objective: To test the hypothesis that circulating molecules present in plasma within days after MI incite EndMT and fibrotic processes in MV leaflets. Method and Results: Ovine MVs harvested 8-10 days after inferior MI (IMI) showed an increase in MV thickness by histology and onset of EndMT, shown by increased CD31/α-smooth muscle actin (α-SMA)+ cells in post-MI MV leaflets (10.5±6.9%) versus sham (2.6±4%). In vitro, post-MI plasma induced EndMT and pro-fibrotic markers and enhanced migration of primary mitral valve endothelial cells (VECs). In contrast, sham plasma did not, despite the presence of TGFβ2 at levels known to induce EndMT in VECs (2 ng/ml). Analysis of sham versus post-MI plasma using a cytokine array revealed a significant drop in the Wnt signaling antagonist secreted frizzled-related protein 3 (sFRP3) in post-MI plasma compared to sham plasma, which was confirmed by ELISA. Addition of recombinant sFRP3 to post-MI plasma reversed its EndMT-inducing effect on mitral VECs, measured by restored VE-cadherin, reduced α-SMA, and reduced TGFβ1-3 expression. Extracellular signal related kinase 1/2 and SMAD2/3 phosphorylation were increased in mitral VEC by post-MI plasma, and both were blocked by supplementing the post-MI plasma with sFRP3. RNA-seq analysis of mitral VECs exposed to post-MI versus sham plasma for 24 hours showed upregulated forkhead box M1 (FOXM1), a transcription factor previously shown to drive fibrosis. FOXM1 was co-localized with CD31 in MV leaflets obtained from sheep at 8-10 days post-MI, which suggests FOXM1 may be linked to EndMT initiation. Blocking FOXM1 with Siomycin A (Sio A) reduced EndMT and pro-fibrotic transcripts in post-MI plasma treated mitral VECs. Finally, post-MI plasma-induced and TGFβ-induced FOXM1 was downregulated by sFRP3. Conclusions: Reduced sFRP3 in post-MI plasma appears to facilitate the onset of TGFβ-driven EndMT and fibrosis in mitral VECs by increasing the transcription factor FOXM1. Restoring sFRP3 levels and/or inhibiting FOXM1 may provide new strategies to minimize maladaptive changes that occur in the MV due to MI.

Project description:Study Smoking and COPD are associated with decreased mucociliary clearance and healthy smokers have shorter cilia in the large airway than nonsmokers. Intraflagellar transport (IFT) is the process by which cilia are produced and maintained. We assessed expression of IFT-related genes in smokers and nonsmokers and evaluated cilia length in the large and small airway of nonsmokers, healthy smokers, and smokers with COPD. Methods Airway epithelium was obtained via bronchoscopic brushing. Affymetrix microarrays were used to evaluate IFT gene expression in 2 independent data sets from large and small airway. Cilia length was assessed by measuring 100 cilia (10 cilia on each of 10 cells) per subject. Results All 40 IFT genes were expressed in the human large and small airway epithelium. In the large airway, 10 IFT genes were down-regulated and 1 up-regulated in smokers. In the small airway, 11 genes were down-regulated and 3 up-regulated in smokers. A set of 8 IFT genes was down-regulated in both data sets. In the large and small airway epithelium, cilia were significantly shorter in healthy smokers than nonsmokers, and significantly shorter in COPD smokers than in both healthy smokers and nonsmokers. Answer to the Question These results support the concept that loss of cilia length contributes to defective mucociliary clearance in COPD, and that smoking-induced changes in expression of IFT genes may be one mechanism of abnormally short cilia in smokers. Strategies to normalize cilia length may be an important avenue for novel COPD therapies. Gene expression was assessed for 40 intraflagellar transport related genes in the LAE of nonsmokers (n=21) and healthy smokers (n=31) and the SAE of an independent group of nonsmokers (n=28) and healthy smokers (n=69). Cilia length was assessed in a total of 228 airway epithelium samples, including 120 LAE samples and 108 SAE samples; a subset of the 228 samples is represented among the 149 samples in this Series.

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Transcriptome Effects of the knockout of Intraflagellar Transport 88 gene in mice Mitral leaflets

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