Journal: bioRxiv
Article Title: A polycomb-independent role of EZH2 in TGFβ1-damaged epithelium triggers a fibrotic cascade with mesenchymal cells
doi: 10.1101/2020.07.29.225300
Figure Lengend Snippet: (a) Haematoxylin-eosin (H&E) staining of stratified and differentiated SAECs (scale bars 50μm). (b) Nanoindentation shows increased stiffness in tSAECs. Box plots display minimum, first quartile, median, third quartile and maximum (n = 5 SAECs donors, *p = 0.0179, two-sided paired t-test). (c) FITC dextran permeability assay reveals loss of epithelial integrity in tSAECs (n = 4 SAECs donors, mean ± s.d., ****p < 0.0001, Linear Regression). (d) ELISA analysis of αSMA levels from NHLFs in mono-(black line) or co-culture with nSAECs (blue) or tSAECs (red) shows an anti-fibrotic effect on nSAECs subjected to apical TGFβ1 for 72 h (n = 5 SAECs and 5 NHLFs donors,*p < 0.05, **p = 0.01, 2-way ANOVA /Tukey’s). (e) Representative western blot analysis of EZH2 immunoprecipitates shows co-precipitation of ph-EZH2, POL2(S2p) and actin in tSAECs. Note the loss of EZH2-bound SUZ12 in tSAECs compared to nSAECs. Unspecific IgG was used as a negative control. (f) ELISA analysis shows decreased E-cad levels in tSAECs in the mono- or co-culture system. This reduction can be rescued by the ROCK inhibitor Y27632 (n = 4 SAECs donors, mean + s.d., *p < 0.05, **p = 0.0052, 2-way ANOVA/Tukey’s). (g) ELISA analysis of aSMA levels shows increased aSMA levels in NHLFs when co-cultured with tSAECs. Blocking actomyosin remodelling by Y27632 can prevent this effect (n = 4 NHLFs donors, mean + s.d., *p < 0.05, 2-way ANOVA/Tukey’s). (h) Representative western blot analysis and quantification show increased ph-EZH2 levels in Bleomycin treated mice compared to saline control group (n = 10 mice / treatment, mean + s.d., *p = 0.04, ****p < 0.001, Mann-Whitney). (i) A model describing TGFβ1-injured epithelium initiating a bi-directional fibrotic crosstalk with fibroblasts. TGFβ1-injured epithelium promotes (1) an EZ-switch from EZH2-PRC2 to EZH1-PRC1, which is required to maintain H3K27me3 at TGFβ1 non-target genes; and (2) a PRC2-independent EZH2 that forms a pro-fibrotic transcriptional complex with POL2(S2p) and nuclear actin to fine-tune transcription at pro-fibrotic genes.
Article Snippet: Where indicated, cells were treated with ROCK inhibitor (Y27632, Sigma-Aldrich, 10 µM), EZH2 inhibitor (GSK126, 10μnM) and TGFβ1 (R&D, 240-B, 1 ng/ml).
Techniques: Staining, FITC-Dextran Permeability Assay, Enzyme-linked Immunosorbent Assay, Co-Culture Assay, Western Blot, Negative Control, Cell Culture, Blocking Assay, MANN-WHITNEY