Medio-Apical Tensions Regulate Tight Junctions of Well-Polarized Madin-Darby Canine Kidney Cells

Tight junctions, which locate at the apicolateral borders of epithelial cells to seal intercellular space, are previously proposed connect circumferential actomyosin belt, whose contractility exerting line tensions affects paracellular transport by opening pores tight junctions. Although junctions known display tortuous morphology, tension leads straight tight-junction morphology as energy minimization. To resolve conflict, here we hypothesized that connected apical actin cortex, exerts an in-plane surface contraction The with orthogonal component can explain both and pore opening. test this hypothesis, laser ablated a spot in well-polarized Madin-Darby Canine Kidney cell. ablation destructs contractile cortex thus reduces tensions, decrease associated proteins, increase areas tortuosity We observed changes MDCK cell sheets due proliferation ROCK inhibitor Y27632 perturbation confirmed trends increasing decreasing junction tortuosity. Surprisingly, our morphological analysis further revealed scutoids on flat sheets, were unexpected based predictions from previous model only considered cell-cell interactions tensions. additional interaction could existence geometry.