FOXS1 drives EMT in retinal pigment, mammary and hepatic epithelial cells through p38 activation by TGFΒ1 and TNFa

Program Number: 5363 Poster Board Number: B0034 Presentation Time: 3:45 PM–5:30 PM FOXS1 drives EMT in retinal pigment, mammary and hepatic epithelial cells through p38 activation by TGFΒ1 and TNFa Timothy A. Blenkinsop1, Tomasz Swigut2, Nathan Boles3, Rajini Srinivasan2, Qingjie Wang3, Jeffrey Stern3, Joanna Wysocka2, Sally Temple3. 1Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY; 2Stanford University, Stanford, CA; 3Neural Stem Cell Institute, Albany, NY. Purpose: To reveal novel factors in the development of Proliferative vitreoretinopathy by examining Retinal Pigment Epithelial (RPE) cells undergoing an Epithelial to Mesenchymal Transition (EMT). We tested the hypothesis that the combination of TGFb1 and TNFa induces a more severe transition in RPE towards acquiring mesenchymal properties, which are two factors RPE are exposed to during rhegmatogenous retinal detachment. Methods: Using cultured adult human RPE we compared the effect of TGFb1 and/or TNFa on inducing EMT in RPE. RPE were cultured in the presence or absence of TGFb1 and/or TNFa. Human globes from donors varied from 51-89 years of age. All experiments conducted using human RPE from at least three individual donors. Comparison of relative gene expression was analyzed using a cutoff of 2-fold expression change for identifying differentially expressed genes. Results: We found that TGFb1 and TNFa pathways synergistically activate an EMT program in adult human RPE, resulting in manifestations similar to those observed in PVR. To characterize the molecular mechanism underlying this cellular transition we mapped epigenomic and transcriptional changes and identified a set of transcription factors that are upregulated upon EMT induction in the adult RPE. Among those, we found that FOXS1, while not expressed in normal RPE, is highly induced in response to TGFb1 and TNFa in combination. In turn, FOXS1 is necessary and sufficient for SNAIL and SLUG expression, two master EMT transcription factors. Furthermore, consistent with a more general role in promoting EMT in various biological contexts, FOXS1 also drives EMT in human mammary and hepatic epithelial cells, and has increased copy numbers in a large number of metastatic cancers. Conclusions: Using an unbiased transcriptomic and epigenetic approach, we identify FOXS1 to be a key regulator in EMT generally, and more specifically, we found FoxS1 may play a role in RPE driven PVR Commercial Relationships: Timothy A. Blenkinsop; Tomasz Swigut, None; Nathan Boles, None; Rajini Srinivasan, None; Qingjie Wang, None; Jeffrey Stern, None; Joanna Wysocka, None; Sally Temple, None