α-Catenin-independent Recruitment of ZO-1 to Nectin-based Cell-Cell Adhesion Sites through Afadin

Abstract

ZO-1 is an actin filament (F-actin)-binding protein that localizes to tight junctions and connects claudin to the actin cytoskeleton in epithelial cells. In nonepithelial cells that have no tight junctions, ZO-1 localizes to adherens junctions (AJs) and may connect cadherin to the actin cytoskeleton indirectly through beta- and alpha-catenins as one of many F-actin-binding proteins. Nectin is an immunoglobulin-like adhesion molecule that localizes to AJs and is associated with the actin cytoskeleton through afadin, an F-actin-binding protein. Ponsin is an afadin- and vinculin-binding protein that also localizes to AJs. The nectin-afadin complex has a potency to recruit the E-cadherin-beta-catenin complex through alpha-catenin in a manner independent of ponsin. By the use of cadherin-deficient L cell lines stably expressing various components of the cadherin-catenin and nectin-afadin systems, and alpha-catenin-deficient F9 cell lines, we examined here whether nectin recruits ZO-1 to nectin-based cell-cell adhesion sites. Nectin showed a potency to recruit not only alpha-catenin but also ZO-1 to nectin-based cell-cell adhesion sites. This recruitment of ZO-1 was dependent on afadin but independent of alpha-catenin and ponsin. These results indicate that ZO-1 localizes to cadherin-based AJs through interactions not only with alpha-catenin but also with the nectin-afadin system.

Localization of mLin-7 at nectin-based cell–cell junctions

“…Conversely, the amount of afadin and ZO-1 in Fractions 10 ± 15 from nectin-2a-DC-EL cells were more than those from nectin-2a-full-EL cells. These results are consistent with our earlier observations (Yokoyama et al, 2001) and indicate that proteins possibly interacting with the cadherin ± catenin and nectin ± afadin systems may be more enriched in Fractions 4 ± 6 from nectin-2a-full-EL cells than in those from nectin-2a-DC-EL cells.…”

“…However, at least, the latrunculin Asensitive actin cytoskeleton is not required for the localization of mLin-7C at the nectin-based cell ± cell junctions. We have previously shown that ZO-1 is associated with the nectin ± afadin system in a cadherin-independent manner (Yokoyama et al, 2001). It is possible that mLin-7C is associated with the nectin ± afadin system through ZO-1, but mLin-7C did not directly interact with ZO-1 (data not shown).…”

“…MBP-Afadin-PDZ, GSTnectin-2a-CP, and Myc-His6-afadin were prepared as described Yokoyama et al, 2001). These recombinant proteins contained the following aa: MBPafadin-PDZ, aa 1007 ± 1125 (PDZ domain); GST-nectin-2a-CP, aa 387 ± 467 (cytoplasmic region of nectin-2a); and MycHis6-afadin, aa 1 ± 1829 (full length).…”

The Src Homology 3 Domain Is Required for Junctional Adhesion Molecule Binding to the Third PDZ Domain of the Scaffolding Protein ZO-1

“…They bind to gap junction connexin proteins via PDZ2 and regulate the size and gating properties of these cell-to-cell channels. They also bind directly to adherens junction proteins, such as ARVCF (PDZ1), AF-6/afadin (SH3) and ␣-catenin (GUK) and regulate the assembly of actomyosin at the adherens junction in polarized epithelial cells (21)(22)(23). However, ZO proteins only localize to the adherens junction early in epithelial biogenesis, prior to the formation of tight junctions, and their localization to gap junctions is spatially distinct from tight junctions.…”

JAM-A is both essential and inhibitory to development of hepatic polarity in WIF-B cells

“…Several reasons lead us to suggest that ZO-1 and PAR3 are the most likely candidates to functionally interact with JAM-A in our system. First, ZO-1 is an early player for junction formation in epithelia (73), and JAM-A is not far behind (20). Second, PAR3 is a member of the PAR/ aPKC complex (17,26), which is required for establishing and maintaining TJs in epithelia, and JAM is the only known membrane anchor for it (reviewed in Refs.…”