Li Yunyuan, Lin Xiaoyue, Kilani Ruhangiz T, Jones Jonathan C R, Ghahary Aziz
Department of Surgery, University of Alberta, Edmonton, Alberta, Canada.
J Cell Physiol. 2007 Sep;212(3):675-81. doi: 10.1002/jcp.21064.
The protein bullous pemphigoid antigen-2 (BPAG2/BP180/collagen type XVII) plays a key role in attachment of basal keratinocytes to epidermal basement membrane. The binding of BP180 with either integrin alpha6, integrin beta4, or bullous pemphigoid antigen-1 (BPAG1/BP230) is critical for this attachment in skin. The protein 14-3-3 sigma, also known as stratifin and a marker for epithelial cells, is a member of a highly conserved small acidic 14-3-3 protein family naturally found in all eukaryotic cells. Here, we have used a 14-3-3sigma GST pull-down screening assay and showed that sigma (sigma) isoform of the 14-3-3 protein family interacts with the cytoplasmic N-terminal domain of BP180. Analysis of a series of truncated or deleted 14-3-3sigma revealed that only intact 14-3-3sigma molecule, but not any of its fragments can interact with BP180. This finding suggests that conformation and possible dimerization of 14-3-3 sigma is essential for this interaction. Further, a BP180 co-immunoprecipitation (IP) and its reverse IP assays were conducted and the results confirmed that 14-3-3 sigma interacts with cytoplasmic domain, but not ecto-domain of the BP180. In conclusion, the finding of this study provides evidence that 14-3-3sigma isoform interacts with BP180 which is a major component of hemidesmosome involved in the attachment of epidermis to the basement membrane in skin. However, the significance of this interaction in hemidesmosome formation and/or attachment needs to be explored.
大疱性类天疱疮抗原2（BPAG2/BP180/ XVII型胶原蛋白）在基底角质形成细胞与表皮基底膜的附着过程中起关键作用。在皮肤中，BP180与整合素α6、整合素β4或大疱性类天疱疮抗原1（BPAG1/BP230）的结合对于这种附着至关重要。蛋白质14-3-3σ，也称为层粘连蛋白，是上皮细胞的标志物，是在所有真核细胞中天然存在的高度保守的小酸性14-3-3蛋白家族的成员。在此，我们使用了14-3-3σ GST下拉筛选试验，结果表明14-3-3蛋白家族的σ（sigma）亚型与BP180的细胞质N末端结构域相互作用。对一系列截短或缺失的14-3-3σ的分析表明，只有完整的14-3-3σ分子，而不是其任何片段能够与BP180相互作用。这一发现表明14-3-3σ的构象和可能的二聚化对于这种相互作用至关重要。此外，进行了BP180共免疫沉淀（IP）及其反向IP试验，结果证实14-3-3σ与BP180的细胞质结构域相互作用，但不与BP180的胞外结构域相互作用。总之，本研究结果提供了证据，即14-3-3σ亚型与BP180相互作用，BP180是半桥粒的主要成分，参与皮肤表皮与基底膜的附着。然而，这种相互作用在半桥粒形成和/或附着中的意义有待探索。
