Vinculin is critical for the robustness of the epithelial cell sheet paracellular barrier for ions

Abstract

The paracellular barrier function of tight junctions (TJs) in epithelial cell sheets is robustly maintained against mechanical fluctuations, by molecular mechanisms that are poorly understood. Vinculin is an adaptor of a mechanosensory complex at the adherens junction. Here, we generated vinculin KO Eph4 epithelial cells and analyzed their confluent cell-sheet properties. We found that vinculin is dispensable for the basic TJ structural integrity and the paracellular barrier function for larger solutes. However, vinculin is indispensable for the paracellular barrier function for ions. In addition, TJs stochastically showed dynamically distorted patterns in vinculin KO cell sheets. These KO phenotypes were rescued by transfecting full-length vinculin and by relaxing the actomyosin tension with blebbistatin, a myosin II ATPase activity inhibitor. Our findings indicate that vinculin resists mechanical fluctuations to maintain the TJ paracellular barrier function for ions in epithelial cell sheets.

Sex differences in the progression from NAFL to NASH: a functional meta-analysis of transcriptomic studies

“…Among these, our results showed the overrepresentation of Vinculin binding term (GO:0017166) in premenopausal women compared to men. This cytoplasmic actin-binding protein is enriched in focal adhesions and adherens junctions, contributes to junction stability (34), and plays an important role as a regulator of apoptosis (35). Of note, although cellular adhesion is a broad topic and not a specific biologic pathway, it was reported to be a GO term consistently enriched in male NASH (36) and Arendt et al also identified genes related to cell-cell adhesion (ANXA2 and MAG) that were differentially expressed between patients with NAFL and NASH (31).…”

“…Of these, the overrepresentation of Vinculin binding term (GO:0017166) has previously been reported in premenopausal women when compared to men. This cytoplasmic actin-binding protein is enriched in focal adhesions and adherens junctions, contributes to junction stability [38], and plays an important role as a regulator of apoptosis [39]. Of note, Arendt et al previously found genes related to cell-cell adhesion (ANXA2 and MAG) that were differentially expressed between patients with NAFL and NASH, but their analysis did not separately consider men and women [40].…”

The mechanobiology of tight junctions

“…During cytokinesis of Xenopus epithelia, the tension from the ingressing contractile ring is transmitted primarily to the AJ, which are reinforced in a vinculindependent manner, allowing for the maintenance of TJ barrier function (Higashi et al 2016). Vinculin was recently shown to be indispensable for the paracellular barrier to ions, by dampening mechanical fluctuations applied to the TJ (Konishi et al 2019). In the upper layer of the stratified epithelium of the skin, enrichment of ZO-1 and development of the TJ barrier correlates with the development of high mechanical tension at AJ (Rubsam et al 2017).…”

Reciprocal Association between the Apical Junctional Complex and AMPK: A Promising Therapeutic Target for Epithelial/Endothelial Barrier Function?

“…Tight junctions (TJs) are vertebrate-specific junctions that are located most apically in epithelial cell–cell junctions. It is generally accepted that adherens junctions (AJs), which are located immediately at the basal side of TJs, are essential for epithelial cell sheet formation, on the basis of which TJs create a paracellular permselective barrier [6,27,28]. Therefore, TJs and AJs are considered to be spatiotemporally and functionally integrated, and are thus often collectively known as apical junctional complexes (AJCs).…”

“…Therefore, TJs and AJs are considered to be spatiotemporally and functionally integrated, and are thus often collectively known as apical junctional complexes (AJCs). In addition to creating a paracellular barrier, AJCs play essential roles in apicobasal cell polarity, mechano-sensing, intracellular signaling cascades, and epithelial morphogenesis [1,6,28,29,30,31,32]. A number of signaling networks are involved in AJC-related events and, over the past 15 years, adenosine monophosphate (AMP)-activated protein kinase (AMPK), a well-known central regulator of energy metabolism signaling pathway, has been shown to have a reciprocal association with AJCs [33,34,35,36,37,38,39,40].…”