Junction-level imaging and modeling of transient leaks in epithelia predicts a dynamic tight junction strand network

Transient tight-junction leaks at single bicellular junctions in MDCK II cells last a median 17 s and are explained by stochastic strand breaking and sealing.

• Why it matters: Global permeability assays miss how small solutes escape through tight junctions over time, leaving the junction-level dynamics behind transient leakage unclear.
• What they did: The study combined fast zinc-based barrier imaging (ZnUMBA) with computational modeling of a dynamic tight junction strand network, measuring leak frequency and duration across wild-type, ZO-1 knockout, ZO-2 knockout, and ZO-1-overexpressing MDCK II cells.
• The result: Simulations show strand breaking and sealing can reproduce both junction-level leak frequencies and durations, with leak frequency tied to the rate ratio and leak duration reflecting sealing; myosin II modulation had little effect, while actin depolymerization compromised the barrier.

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