(776f) Cell-Cell Contact Promotes Tgfß1-Induced Epithelial-Myofibroblast Transition Via Notch1

Myofibroblasts aid in wound healing and upon aberrant and chronic activation they can contribute to the development of pathological conditions including fibrosis and cancer. Myofibroblasts can develop from epithelial cells through an epithelial-mesenchymal transition (EMT), a process in which epithelial cells lose cell-cell adhesion, exhibit morphological changes, and upregulate the expression of cytoskeletal proteins including alpha smooth muscle actin (αSMA). Previous studies have suggested that complete disruption of cell-cell contacts is necessary for induction of EMT by transforming growth factor (TGF)-β1. However, it is not clear how partial cell-cell contacts (such as those experienced by cells along a wound edge) impact EMT progression. Here, we employed a microfabrication approach to decouple the effects of cell-cell contact and cell-matrix adhesion in TGFβ1 induction of EMT. We find that when cells are permitted to spread, the presence of cell-cell contacts enhances myofibroblast development from epithelial cells when compared to single cells lacking neighbors. Furthermore, we find that cell spreading and intercellular contacts together control the activation and subcellular localization of Notch1. Blocking cell spreading abrogates TGFβ1-induced Notch1 activation and expression of EMT markers. Moreover, pharmacological inhibition of Notch activation and knockdown of Notch1 abated cell-cell contact mediated αSMA expression. These studies provide insight into how cell-cell and cell-matrix adhesive cues together contribute to the development of myofibroblasts along wound edges and may suggest approaches to promote wound healing or to prevent fibrosis and cancer.