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

天疱疮（Pemphigus， P）是一种自身免疫性大疱性疾病，由抗桥粒黏附分子的自身抗体引起桥粒破坏引起，桥粒黏附分子为寻常型P （PV）的桥粒蛋白3 （Dsg3）或叶状P （PF）的桥粒蛋白1 （Dsg1）。目前尚不清楚PV-IgG与粘粒蛋白结合后是如何引起水疱的。本研究的目的是阐明pv - igg诱导水泡的机制。我们之前已经证明PV-IgG引起Dsg3的磷酸化，随后Dsg3从桥粒中消失。然而，由于PV-IgG含有针对Dsg3以外的其他抗原的抗体，因此尚不确定PV-IgG的Dsg3-耗尽活性是否仅由于抗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针对Dsg3的致病性和非致病性单克隆抗体，确定了这是由抗Dsg3活性引起的。我们还证明了耗竭活性与致病性成正比，并通过移液解离试验降低了细胞-细胞粘附强度。此外，单纯大疱性表皮松解是由表皮基底细胞中主要的角蛋白5或角蛋白14突变引起的。我们发现了一种新的EBS，它是由一种新的突变（K5: 1649delG）引起的，具有一种新的声型，显示循环的水泡病变。我们制造了K5突变的转基因小鼠，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.