POS0328 ENGRAILED 1 COORDINATES CYTOSKELETAL ORGANIZATION TO PROMOTE MYOFIBROBLAST DIFFERENTIATION AND FIBROTIC TISSUE REMODELING

Background: Engrailed 1 (EN1) is a homeodomain-containing transcription factor with essential roles in embryonic development. In most cell types, the expression of EN1 restricted to However, under pathological conditions, can be re-expressed promote phenotypical adaptation. En1 transiently expressed developing dermis murine embryos distinct fibroblast lineage and silenced before birth (1). Former EN1-expressing cells give rise subpopulation fibroblasts that has high capacity for extracellular matrix production adult skin. The role systemic sclerosis (SSc) was previously not explored. Objectives: To study activation tissue fibrosis. Methods: Bulk RNA-Seq or SP1 ChIP-Seq were performed from cultured human dermal fibroblasts. inhibited by siRNA. Cytoskeletal drugs paclitaxel, vinblastin ROCK inhibitor (Y27632) used modulate cytoskeleton knockdown overexpressing evaluated functional experiments overexpression standard 2D culture systems as well 3D skin equivalent models. fibrosis further studied fl/fl X Col6Cre mice, fibroblast-specific knockout three complementary mouse models: constitutively active TGFß-receptor I (TBRI CA ), bleomycin-induced TSK1 mice. Results: Pathologically activated SSc patients express higher levels compared age sex matched healthy individuals vitro . TGFβ induces SMAD3-dependent manner both Knockdown prevents TGFβ-induced activation, whereas fosters pro-fibrotic effects increased αSMA, stress fibers collagen. RNA sequencing demonstrates gene profile functionally related organization activation. silico analyses promoters target genes coupled siRNA-mediated demonstrated regulates these modulating activity regulatory modules contain factors specificity protein (SP) family. Functional selective modulators microtubule polymerization confirm coordinating on re-organization during myofibroblast differentiation conventional equivalents. Consistently, mice demonstrate impaired fibroblast-to-myofibroblast transition, reduced thickening collagen deposition TBRI , Conclusion: We characterize homeodomain molecular amplifier signaling coordinates cytoskeletal SP-dependent manner. might thus novel candidate targeted therapies interfere fibrotic diseases. References: [1]Rinkevich Y, Walmsley GG, Hu MS, Maan ZN, Newman AM, Drukker M, et al. Skin Identification isolation intrinsic fibrogenic potential. Science. 2015;348(6232):aaa2151. Disclosure Interests: Andrea-Hermina Györfi: None declared, Alexandru-Emil Matei: Maximilian Fuchs: Aleix Rius Rigau: Xuezhi Hong: ZHU Honglin: Markus Luber: Christina Bergmann: Clara Dees: Ingo Ludolph: Raymund Horch: Oliver Distler Consultant of: Actellion, AbbVie, Acceleron Pharma, Anamar, Amgen, Blade Therapeutics, CSL Behring, ChemomAb, Ergonex, Glenmark GSK, Inventiva, Italfarmaco, iQvia, Medac, Medscape, Lilly, Sanofi, Target BioScience, UCB, Bayer, Boehringer Ingelheim, Catenion, iQone, Menarini, Mepha, Novartis, Mitsubishi, MSD, Roche, Pfizer, Georg Schett: Meik Kunz: Jörg H.W. Actelion, Active Biotech, ARXX, Bayer Celgene, Galapagos, JB RuiYi UCB., Grant/research support from: Array Biopharma, aTyr, BMS, Sanofi-Aventis, RedX, UCB