Requirement of the F ‐actin‐binding activity of l‐afadin for enhancing the formation of adherens and tight junctions

The apical junctional complex consists of adherens junctions (AJs) and tight junctions (TJs) in polarized epithelial cells, which are attached to each other to form a sheet. Actin filaments (F‐actin) are associated with AJs and TJs and required for the formation and maintenance of this complex. l‐Afadin is an F‐actin‐binding protein, which is localized at AJs through binding to the cell adhesion molecule nectin, and regulates the formation of AJs and TJs. However, the role of the F‐actin‐binding activity of l‐afadin for the formation of the apical junctional complex remains unknown. We generated here the cultured EpH4 mouse mammary epithelial cells in which afadin was genetically ablated. In the Ca2+ switch assay, the formation of both AJs and TJs was markedly impaired in the afadin‐deficient cells. Re‐expression of l‐afadin in the afadin‐deficient cells fully restored the formation of both AJs and TJs, but the re‐expression of the l‐afadin mutant lacking the FAB domain did not completely restore the formation of AJs or TJs. These results indicate that the F‐actin‐binding activity of l‐afadin is required for enhancing the formation of both AJs and TJs.

We found that the genetic ablation of the nectin‐binding protein afadin in cultured EpH4 mouse mammary epithelial cells led to the delayed formation of adherens junctions (AJs) and tight junctions (TJs) in the calcium switch assay. In addition, we found that the F‐actin‐binding domain of l...

Source: Genes to Cells - February 12, 2018 Category: Genetics & Stem Cells Authors: Shotaro Sakakibara, Tomohiko Maruo, Muneaki Miyata, Kiyohito Mizutani, Yoshimi Takai Tags: ORIGINAL ARTICLE Source Type: research