Transient interactions drive the lateral clustering of cadherin-23 on membrane

Abstract

Cis and trans-interactions in cadherins are the foundations of multicellularity. While the trans-interaction mediate cell-cell adhesion, the cis-interaction is postulated as strengthening to trans by clustering. The well-accepted model in cadherin-adhesion is that the trans precedes cis via a diffusion-trap kinetic model. Here we report that cadherin-23, a non-classical cadherin with an extended extracellular region, undergoes clustering in solution via lateral interactions independent of trans and phase separate as liquid droplets. In cellulo using fluorescence-recovery after the photobleaching, we noticed a significantly slow-diffusion of cadherin-23 at the intercellular junctions, indicating the diffusion of a cluster. The cis-clustering accelerates the cell-cell adhesion and, thus, kinetically controls cell-adhesion via cis precedes trans model. Though the connection of cis-clustering with the rapid adhesion is yet to explore, M2-macrophages that predominantly express cadherin-23 undergo fast attachments to circulatory tumor cells during metastasis.

Redefining the structure of tip-links in hair-cells

“…The attachments of the individual cadherins were confirmed from the C-terminal GFP tags (Figure 2A) . Since free diffusion of proteins tethered to the membrane is essential for lateral proximity, and so lateral complexation, we confirm the diffusion of proteins from FRAP experiments on GUVs tethered with Pcdh15 and Cdh23, respectively 20 (Figure S1, Table S1) .…”

“…We used an optimal concentration of 6 µM for Cdh23 EC1-27 for the PICUP as beyond this we always observed smearing of bands in the SDS-PAGE. Notably, at higher concentrations (> 4 µM), Cdh23 EC1-27 undergoes liquid-liquid phase separation 20 . We observed dimer bands at ~650 kDa (Figure 1C) in all calcium concentrations under PICUP, except at the endolymph [Ca 2+ ] of 50 µM.…”

“…Cadherins are trans-membrane proteins and are naturally confined for lateral diffusions. Moreover, Cdh23 engages in weak transient interactions and forms cis-clusters prior to even any trans-mediated localization at the cell-cell junction 20 . We, thus, hypothesized that the cis-clustering of Cdh23 on the membrane may assist the lateral dimerization of Cdh23.…”