A weak link with actin organizes tight junctions to control epithelial permeability

Abstract

words or fewer)In vertebrates, epithelial permeability is regulated by the tight junction (TJ) formed by specialized adhesive membrane proteins, adaptor proteins, and the actin cytoskeleton. Despite the TJ's critical physiological role, a molecular-level understanding of how TJ assembly sets the permeability of epithelial tissue is lacking. Here, we identify a 28-amino acid sequence in the TJ adaptor protein ZO-1 that is responsible for actin binding and show that this interaction is essential for TJ permeability. In contrast to the strong interactions at the adherens junction, we find that the affinity between ZO-1 and actin is surprisingly weak, and we propose a model based on kinetic trapping to explain how affinity could affect TJ assembly. Finally, by tuning the affinity of ZO-1 to actin, we demonstrate that epithelial monolayers can be engineered with a spectrum of permeabilities, which points to a new target for treating transport disorders and improving drug delivery.

Cell–cell interfaces as specialized compartments directing cell function

“…While each of the biophysical signatures of cell-cell interfaces described above involves time as a component -diffusion and residence time at an interface, cooperative binding and cluster size increase, mechanosensitivity and bond lifetime -an emerging feature of the interfacial compartment is orchestration of multiple time-dependent events into a temporally-coordinated process. For instance, recent work on tight junctions suggests that the kinetics of alignment between dynamic claudin strands in the membrane and the stiff actin cytoskeleton might play an outsized role in the time-dependence of epithelial permeability 79 . In other examples, temporally coordinated processes are achieved through stepwise assembly of signaling clusters, biomolecular condensates, and, in some cases, regulation of gene expression.…”

Azobenzene-based sinusoidal surface topography drives focal adhesion confinement and guides collective migration of epithelial cells

“…A double knockout cell line was created by repeating the same protocol above with a TJP2-targeted gRNA (gRNA sequence: GTA CAC TGT GAC CCT ACA AAA). Double knockout of clonal lines was verified with western blotting against ZO-1 and ZO-2 and genomic sequencing 43 .…”