Intercellular adhesion of keratinocytes depends critically on desmosomes that, during maturation, acquire a hyperadhesive and thus Ca2+ independent state. Here, we investigated the roles of desmoglein (Dsg) 3 and plakophilins (Pkps) in hyperadhesion. Atomic force microscopy single molecule force mappings revealed increased Dsg3 molecules but not Dsg1 molecules binding strength in murine keratinocytes. However, keratinocytes lacking Dsg3 or Pkp1 or 3 revealed reduced Ca2+ independency. In addition, Pkp1- or 3-deficient keratinocytes did not exhibit changes in Dsg3 binding on the molecular level. Further, wild-type keratinocytes showed increased levels of Dsg3 oligomers during acquisition of hyperadhesion, and Pkp1 deficiency abolished the formation of Ca2+ independent Dsg3 oligomers. In concordance, immunostaining for Dsg1 but not for Dsg3 was reduced after 24 h of Ca2+ chelation in an ex vivo human skin model, suggesting that desmosomal cadherins may have different roles during acquisition of hyperadhesion. Taken together, these data indicate that hyperadhesion may not be a state acquired by entire desmosomes but rather is paralleled by enhanced binding of specific Dsg isoforms such as Dsg3, a process for which plaque proteins including Pkp 1 and 3 are required as well.

中文翻译：

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桥粒超粘连伴随着桥粒芯蛋白 3 分子结合强度的增强

角质形成细胞的细胞间粘附关键取决于桥粒，在成熟过程中，桥粒获得高度粘附，从而获得独立于 Ca2+ 的状态。在这里，我们研究了桥粒芯蛋白 (Dsg) 3 和 plakophilins (Pkps) 在粘连中的作用。原子力显微镜单分子力映射显示增加的 Dsg3 分子但不是 Dsg1 分子在鼠角质形成细胞中的结合强度。然而，缺乏 Dsg3 或 Pkp1 或 3 的角质形成细胞显示降低的 Ca2+ 独立性。此外，Pkp1 或 3 缺陷的角质形成细胞在分子水平上没有表现出 Dsg3 结合的变化。此外，野生型角质形成细胞在获得超粘连过程中显示出更高水平的 Dsg3 寡聚体，并且 Pkp1 缺乏消除了 Ca2+ 独立 Dsg3 寡聚体的形成。相应地，在离体人类皮肤模型中，在 Ca2+ 螯合 24 小时后，Dsg1 的免疫染色减少，但 Dsg3 的免疫染色减少，表明桥粒钙粘蛋白在获得超粘连过程中可能具有不同的作用。综上所述，这些数据表明，过度粘附可能不是整个桥粒获得的状态，而是与特定 Dsg 同种型（如 Dsg3）的增强结合平行，这一过程也需要包括 Pkp 1 和 3 在内的斑块蛋白。