N-glycosylation alters cadherin-mediated intercellular binding kinetics

Abstract

We present direct evidence that the N-glycosylation state of neural cadherin impacts the intrinsic kinetics of cadherin-mediated intercellular binding. Micropipette manipulation measurements quantified the effect of N-glycosylation mutations on intercellular binding dynamics. The wild-type protein exhibits a two-stage binding process in which a fast, initial binding step is followed by a short lag and second, slower transition to the final binding stage. Mutations that ablate N-glycosylation at three sites on the extracellular domains 2 and 3 of neural cadherin alter this kinetic fingerprint. Glycosylation does not affect the affinities between the adhesive N-terminal domains, but instead modulates additional cadherin interactions, which govern the dynamics of intercellular binding. These results, together with previous findings that these hypo-glycosylation mutations increase the prevalence of cis dimers on cell membranes, suggest a binding mechanism in which initial adhesion is followed by additional cadherin interactions, which enhance binding but are modulated by N-glycosylation. Given that oncogene expression drives specific changes in N-glycosylation, these results provide insight into possible mechanisms altering cadherin function during tumor progression.