RESUMEN
Epithelial cell divisions are coordinated with cell loss to preserve epithelial integrity. However, how epithelia adapt their rate of cell division to changes in cell number, for instance during homeostatic turnover or wounding, is not well understood. Here, we show that epithelial cells sense local cell density through mechanosensitive E-cadherin adhesions to control G2/M cell-cycle progression. As local cell density increases, tensile forces on E-cadherin adhesions are reduced, which prompts the accumulation of the G2 checkpoint kinase Wee1 and downstream inhibitory phosphorylation of Cdk1. Consequently, dense epithelia contain a pool of cells that are temporarily halted in G2 phase. These cells are readily triggered to divide following epithelial wounding due to the consequent increase in intercellular forces and resulting degradation of Wee1. Our data collectively show that epithelial cell division is controlled by a mechanical G2 checkpoint, which is regulated by cell-density-dependent intercellular forces sensed and transduced by E-cadherin adhesions.
Asunto(s)
Cadherinas , Células Epiteliales , Cadherinas/metabolismo , Proteínas de Ciclo Celular/metabolismo , División Celular , Células Epiteliales/metabolismo , Puntos de Control de la Fase G2 del Ciclo Celular , Mitosis , FosforilaciónRESUMEN
Molecular Tension Microscopy has been increasingly used in the last years to investigate mechanical forces acting in cells at the molecular scale. Here, we describe a protocol to image the tension of the junctional protein E-cadherin in cultured epithelial cells undergoing Epithelial-Mesenchymal Transition (EMT). We report how to prepare cells and induce EMT, and how to acquire, analyze, and quantitatively interpret FRET data.
Asunto(s)
Cadherinas/metabolismo , Transición Epitelial-Mesenquimal , Transferencia Resonante de Energía de Fluorescencia/métodos , Animales , Perros , Células de Riñón Canino Madin DarbyRESUMEN
Phase separation underlies functional compartmentalization in living systems. Two recent studies (Beutel et al. and Schwayer et al.) show that zonula occludens (ZO) proteins of tight junctions (TJs) condense into compartments within the cytoplasm that display liquid properties. This ability to condense predicts normal TJ assembly and epithelial barrier function which are essential for vertebrate embryogenesis.