Randall Division of Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK; St Johns Institute of Dermatology, King's College London, Guys Campus, London, UK; Division of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Brisbane, Queensland, Australia.
Randall Division of Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK; St Johns Institute of Dermatology, King's College London, Guys Campus, London, UK.
J Invest Dermatol. 2014 Mar;134(3):773-782. doi: 10.1038/jid.2013.382. Epub 2013 Sep 11.
Bullous pemphigoid antigen 1 (BPAG1-e, also known as BP230) is a member of the plakin family of hemidesmosome cytoskeletal linker proteins that is encoded by an isoform of the dystonin (DST) gene. Recently, we reported two unrelated families with homozygous nonsense mutations in this DST isoform that led to ultrastructural loss of hemidesmosomal inner plaques and clinical features of trauma-induced skin fragility. We now demonstrate that keratinocytes isolated from these individuals have significant defects in adhesion, as well as increased cell spreading and migration. These mutant keratinocytes also display reduced levels of β4 integrins at the cell surface but increased total protein levels of keratin-14 and β1 integrins. These alterations in cell behavior and protein expression were not seen in control keratinocytes in which BPAG1-e expression had been silenced by stable expression of short hairpin RNA to target DST. The failure of knockdown approaches to recapitulate the changes in morphology, adhesion, and migration seen in patient cells therefore suggests such approaches are not appropriate to study loss of this protein in vivo. The contrasting findings in keratinocytes harboring naturally occurring mutations, however, demonstrate a previously unappreciated key role for BPAG1-e in regulating keratinocyte adhesion and migration and suggest a requirement for this protein in controlling functional switching between integrin types in epithelial cells.
大疱性类天疱疮抗原 1（BPAG1-e，也称为 BP230）是桥粒细胞骨架连接蛋白 plakins 家族的成员，由 dystonin（DST）基因的一种异构体编码。最近，我们报道了两个无亲缘关系的家族，其 DST 异构体中存在纯合无义突变，导致桥粒内斑的超微结构丢失和创伤诱导的皮肤脆弱的临床特征。我们现在证明，这些个体分离的角质形成细胞在黏附中存在显著缺陷，以及细胞扩展和迁移增加。这些突变的角质形成细胞还显示细胞表面的 β4 整联蛋白水平降低，但角蛋白-14 和 β1 整联蛋白的总蛋白水平增加。在通过稳定表达短发夹 RNA 靶向 DST 沉默 BPAG1-e 表达的对照角质形成细胞中，没有观察到这些细胞行为和蛋白表达的改变。因此，敲低方法未能重现患者细胞中观察到的形态、黏附和迁移变化，表明这些方法不适合研究体内这种蛋白的缺失。然而，携带天然发生突变的角质形成细胞的对比发现，BPAG1-e 在调节角质形成细胞黏附和迁移方面起着以前未被认识的关键作用，并表明该蛋白在控制上皮细胞中整合素类型的功能转换中是必需的。
