Molecular controls of cytoskeleton and cell-cell adhesions and molecular cell biology of bullous diseases

天疱疮(P)是一种自身免疫性大疱性疾病，由抗桥粒黏附分子自身抗体Dsg3或DSG1引起的自身免疫性大疱病。目前尚不清楚PV-Ig G与桥粒蛋白结合后是如何诱发水泡的。本研究的目的是阐明PV-Ig G诱导水泡的机制。我们先前已经证明，PV-Ig G导致Dsg3的磷酸化，随后Dsg3从桥粒中耗尽。然而，由于PV-Ig G含有针对Dsg3以外的其他抗原的抗体，目前还不能确定PV-Ig G的Dsg3耗竭活性是否仅仅是由于抗Dsg3活性。在这项研究中，我们通过在培养的角质形成细胞中使用致病的和非致病的抗Dsg3的单抗来确定这是由抗Dsg3的活性引起的。我们还证明了耗竭活性与致病性成正比，并通过移液解离实验检测到细胞-细胞黏附强度的降低。此外，单纯性大疱性疱疹是由角蛋白5或14突变引起的，角蛋白5或14是表皮基底细胞中的主要角蛋白。我们发现了一种新的EBS，是由一种新的突变(K5：1649delG)引起的，该突变具有一种新的表型，表现为循环水泡病变。我们用K5的这种突变制作了转基因小鼠，但没有产生表型。

Pemphigus (P) is an autoimmune bullous disease caused by disruption of desmosomes due to autoantibodies against desmosomal adhesion molecules, desmoglein 3 (Dsg3) for P vulgaris (PV) or Dsg1 for P foliaceus (PF). It is yet unknown how blisters are induced after PV-IgG bound to desmogleins. The aim of this study is to elucidate the mechanisms of PV-IgG-induced blistering. We have previously shown that PV-IgG causes phosphorylation of Dsg3 followed by depletion of Dsg3 from desmosomes. However, since PV-IgG contains antibodies against other antigens than Dsg3, it is not yet determined whether Dsg3- depletion activity of PV-IgG is due to only anti-Dsg3 activity. In this study we determined that this is caused by anti-Dsg3 activity by using pathogenic and non-pathogenic monoclonal antibodies against Dsg3 in cultured keratinocytes. We also demonstrated that the depletion activity is proportional to the pathogenicity and exerts a decrease in the cell-cell adhesion strength as examined by pipetting dissociation assay. Besides, Epidemolysis bullosa simplex is caused by mutation of keratin 5 or 14, which are the major keratins in epidermal basal cells. We have found out a new type of EBS, caused by a new mutation (K5 : 1649delG) with a new phonotype showing circulated blistering lesions. We made transgenic mice with this mutation of K5 but resulting in no phenotype.