Biophysical Society Thematic Meeting| Aussois 2019

Biology and Physics Confront Cell-Cell Adhesion

Poster Abstracts

16-POS Board 16 RECEPTOR TYROSINE KINASE REGULATION OF EPIDERMAL JUNCTIONAL MECHANICS AND BARRIER FUNCTION Alexander Kyumurkov 1 ; Emmi Wachsmuth 1 ; Carien Niessen 1 ; 1 University of Cologne, Dermatology, Köln, Germany The insulin and IGF-1 growth factor receptor tyrosine kinases (IR, IGF-1R) are key regulators of growth. Recent work have also implicated these receptors in the regulation of oriented division, intercellular junction and epithelial barrier formation. Specifically, we showed that epidermal insulin/IGF-1 signaling (IIS) controls epidermal morphogenesis, stratification and barrier formation through as yet in part undefined mechanisms. To address whether and how epidermal IIS control junction and epithelial tight junction (TJ) barrier function directly, we performed transepithelial resistance measurements on keratinocytes from mice with an epidermal deletion of IR and/or IGF-1R. Only loss of both receptors but not IGF1-1R alone strongly impaired TJ barrier formation ability. In agreement, high-resolution whole mount imaging on IGF-1R epi-/- epidermis did not reveal a strong differences in TJ ZO-1 staining nor F-actin in the TJ-containing SG2 layer. However, phospho-myosin staining was altered, indicating that IGF-1R regulates actomyosin- dependent tensile responses. Employing unilateral cyclic stretch we showed that stress fibers in IGF-1R -/- keratinocytes were much thicker and showed increased phospho-myosin, indicating a role for IGF-1R in regulating tensile properties. Moreover vinculin, but not paxillin-stained adhesions, were reinforced in the IGF1R -/- keratinocytes, coinciding with stiffening of the cortical actomyosin network of these cells. At present, we are performing laser ablation and atomic force microscopy to probe whether IGF-1R regulates junctional and cortical tension. In addition, to control spatiotemporally activation of IGF-1R we are developing optogenetic IGF1R probes. In conclusions, our data show that epidermal IIS signaling regulates junctions and the actomyosin cytoskeleton to control epidermal barrier function.

55