Molecular studies of structures and functions of cytoskeleton and cell-cell junctions in blistering mechanisms for pemphigus an pemphigoid as a model system

表皮角质形成细胞响应细胞外信号，控制细胞间和细胞-基质连接粘连，从而控制正常的角质形成。本课题拟以自身免疫性水疱病、先天性大疱性表皮松解症和角化症为模型系统，从信号转导角度阐明细胞骨架和粘附分子的结构和功能调控的分子机制。这种方法可以为我们提供细胞骨架和细胞连接的基本方面与大泡性和角化性疾病的临床方面之间的相互益处。直到去年，我们在阐明寻常型天疱疮（Pemphigus vulgaris， PV）水疱形成的分子机制方面取得了一定的进展。寻常型天疱疮是一种自身免疫性水疱皮肤病，其特征是对特定桥粒成分桥粒蛋白（Dsg） 3的自身抗体。我们研究了寻常型天疱疮(PV)- igg结合对钙蛋白激酶C （PKC）介导的纤溶酶原激活物（muPA）分泌和muPA受体表达的影响[J] .中国皮肤医学杂志，1995,10:482-487,1997。今年，我们发现PV-PLC参与了PV-IgG诱导的二酰基甘油的双相增加，这应该会导致PKC的激活（J Invest Dermatol 109: 650-655,1997），并且PV-IgG单独结合诱导了dsg3和血小板红蛋白（PG）的磷酸化。虽然在正常IgG作用下，Dsg3和PG会被PV-IgG免疫沉淀共沉淀，但在PV-IgG刺激下，PG不会与Dsg3共沉淀，这表明PV-IgG与Dsg结合导致Dsg与PG解离。我们提出，这些对PV-IgG的异常信号转导反应，导致Dsg3和PG磷酸化及其解离，可能从细胞内部破坏桥粒的完整性，而PV-IgG诱导的PKC信号转导，与细胞表面的uPA分泌及其受体表达相关，可能介导细胞外部先前存在的桥粒的分离（J clinin Invest修订提交）。我们还发现180kDa的大疱性类天疱疮抗原（BPAG2）被TPA磷酸化，并且这种磷酸化总是与BPAG2 （230 kDa）从细胞质溶胶到质膜的易位有关（J Invest Dermatol修订提交）。少

Epidermal keratinocytes response to the extracellular signals leading to control cell-cell and cell-matrix junctional adhesions, so as to control normal keratinization. The purposes of this research project are to elucidate molecular mechanisms for the control of structures and functions cytoskeletons and adhesion molecules in terms of signal transduction, by studying autoimmune blistering diseases, congenital epidermolysis bullosa and keratinization disorders as a model system. This approach may provide us with a mutual benefits between basic aspects of cytoskeleton and cell junctions and clinical aspects of bullous and keratinizing disorders.Until last year, we had made a certain progress in clarifying the molecular mechanisms for blister formation in Pemphigus vulgaris (PV), which is an autoimmune blistering skin disease characterized by autoantibodies to a specific desmosomal constituent, desmoglein (Dsg) 3. We showed an involvement of calcium- and protein kinase C (PKC)-mediated i … More ntracellular signaling which leads to plasminogen activator (muPA) secretion and muPA receptor expression in response to pemphigus vulgaris (PV)-IgG-binding (J Invest Dermatol 104 : 33-37,1995,105 : 482-487,1997). This year, we showed that involvement of PV-PLC in PV-IgG-induced Biphasic increase in diacylglycerol, which is supposed to cause activation of PKC (J Invest Dermatol 109 : 650-655,1997), and that PV-IgG binding alone induced the phosphorylation of Dsg 3 and plakoglobin (PG). Although Dsg3 and PG were coprecipitated by PV-IgG-immunoprecipitation when treated with normal IgG,PG was not coprecipitated with Dsg3 when stimuated with PV-IgG,suggesting that PV-IgG-binding to Dsg causes the dissociation of Dsg from PG.We propose that these aberrant signal transduction responses to PV-IgG,which lead to Dsg3 and PG phosphorylation and their dissociation, may impair the desmosomal integrity from the inside of the cell, while PV-IgG-induced PKC signaling, linked with uPA secretion and its receptor expression on the cell surface, may mediate to dissociate preexisting desmosomes from the outside of the cell (J Clin Invest revised submitted). We also showed that 180kDa bullous pemphigoid antigen (BPAG2) is phosphorylated with TPA and this phosphorylation is always associated with translocation of BPAG2 (230 kDa) from cytosol to plasma membrane (J Invest Dermatol revised submitted). Less