Study of the keratin molecular mechanism based on the analysis of pathological model in epidermalysis bullosaa simplex

我们对日本和韩国的两个不相关的家庭进行了实验，这些家庭的患者患有独特类型的EBS和角蛋白基因KRT 5的新突变;即，移码和延迟终止密码子与之前描述的任何亚型不一致。患者表现为游走性环状红斑，红斑累及的环状带状区域有多发性小泡。皮肤活检的电子显微镜检查显示，在基底细胞中的角蛋白中间丝的数量减少，而没有张力丝聚集。我们在这两个病例中发现了一个新的杂合性缺失突变（KRT 5的1649 delG）。预测该缺失产生突变K5蛋白，其末端41个氨基酸移码，并且由于延迟终止密码子而比野生型K5蛋白长35个氨基酸。患者皮肤在免疫组织化学和免疫印迹中均显示对识别突变的伸长氨基酸的特异性抗体的阳性反应。由于在独立的家族中发现了相同的异常伸长突变KRT 5基因，因此预测的异常伸长角蛋白蛋白可能导致从未报道过的非典型临床表型。为了进一步研究延长角蛋白5的功能，分析了角蛋白5在转基因小鼠和转染的角质形成细胞中的表达。

We experimented two unrelated families in Japan and Korea having patients with an unique type of EBS and a novel mutation in the keratin gene, KRT5 ; i.e., frameshift and delayed stop codon inconsistent with any subtype described before. The patients showed migratory circinate erythema and multiple vesicles on the circular belt-like areas affected by erythema. Electron microscopy of skin biopsies showed a reduction in the number of keratin intermediate filaments in the basal cells without tonofilament clumping. We identified a novel heterozygous deletion mutation (1649delG of KRT5) in both cases. This deletion is predicted to produce a mutant K5 protein with a frameshift of its terminal 41 amino acids, and 35 amino acids longer than the wild type K5 protein due to a delayed termination codon. Patient skin show positive reactivity to specific antibody which recognize the mutant elongated amino acids both in immunohistochemistry and immunoblotting. Since the same abnormal elongated mutant KRT5 gene was found in the independent families, the predicted abnormal elongated keratin protein is likely to lead to an atypical clinical phenotype that has never been reported. Furthermore to investigate the function of elongated keratin 5 protein, keratin 5 expression in transgenic mice and transfected keratinocyte was analyzed.