Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
J Cell Sci. 2012 May 15;125(Pt 10):2478-85. doi: 10.1242/jcs.101147. Epub 2012 Feb 17.
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.
我们提供了直接证据表明神经钙黏蛋白的 N-糖基化状态影响钙黏蛋白介导的细胞间结合的固有动力学。微管操纵测量量化了 N-糖基化突变对细胞间结合动力学的影响。野生型蛋白表现出两步结合过程，其中快速初始结合步骤之后是短暂的滞后和第二个较慢的过渡到最终结合阶段。在神经钙黏蛋白的细胞外结构域 2 和 3 上的三个位点上消除 N-糖基化的突变改变了这种动力学特征。糖基化不影响粘附 N 端结构域之间的亲和力，而是调节额外的钙黏蛋白相互作用，从而控制细胞间结合的动力学。这些结果与先前的发现一致，即这些低聚糖突变增加了细胞膜上顺式二聚体的普遍性，表明一种结合机制，其中初始粘附后会发生额外的钙黏蛋白相互作用，这些相互作用增强了结合，但受到 N-糖基化的调节。鉴于癌基因表达驱动 N-糖基化的特定变化，这些结果提供了对肿瘤进展过程中钙黏蛋白功能可能发生变化的机制的深入了解。
