Affiliation:
1. Department of Pathology, Leiden University Medical Centre, Leiden, The Netherlands
Abstract
ABSTRACT
Ep-CAM, an epithelium-specific cell-cell adhesion molecule (CAM) not structurally related to the major families of CAMs, contains a cytoplasmic domain of 26 amino acids. The chemical disruption of the actin microfilaments, but not of the microtubuli or intermediate filaments, affected the localization of Ep-CAM at the cell-cell boundaries, suggesting that the molecule interacts with the actin-based cytoskeleton. Mutated forms of Ep-CAM were generated with the cytoplasmic domain truncated at various lengths. All of the mutants were transported to the cell surface in the transfectants; however, the mutant lacking the complete cytoplasmic domain was not able to localize to the cell-cell boundaries, in contrast to mutants with partial deletions. Both the disruption of the actin microfilaments and a complete truncation of the cytoplasmic tail strongly affected the ability of Ep-CAM to mediate aggregation of L cells. The capability of direct aggregation was reduced for the partially truncated mutants but remained cytochalasin D sensitive. The tail truncation did not affect the ability of the transfectants to adhere to solid-phase-adsorbed Ep-CAM, suggesting that the ability to form stable adhesions and not the ligand specificity of the molecule was affected by the truncation. The formation of intercellular adhesions mediated by Ep-CAM induced a redistribution to the cell-cell boundaries of α-actinin, but not of vinculin, talin, filamin, spectrin, or catenins. Coprecipitation demonstrated direct association of Ep-CAM with α-actinin. Binding of α-actinin to purified mutated and wild-type Ep-CAMs and to peptides representing different domains of the cytoplasmic tail of Ep-CAM demonstrates two binding sites for α-actinin at positions 289 to 296 and 304 to 314 of the amino acid sequence. The results demonstrate that the cytoplasmic domain of Ep-CAM regulates the adhesion function of the molecule through interaction with the actin cytoskeleton via α-actinin.
Publisher
American Society for Microbiology
Subject
Cell Biology,Molecular Biology
Cited by
81 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献