An animal model for keratosis

银屑病和银屑病是最常见的皮肤病，临床上以角化过度或角化过度为特征。对于这些疾病，还没有明确的动物模型。维甲酸或其衍生物类维甲酸是常用的治疗药物，但目前尚无动物模型意义上的药物评价模型。我们的帮助是构建组织特异性表达点突变的视黄酸受体的转基因小鼠，该受体对内源性视黄酸受体具有显性-负性效应。我们构建了K14启动子连接到点突变的视黄酸受体cDNA的载体，得到的转基因小鼠显示了一个点突变的视黄酸受体的表皮特异性表达。通过从转基因小鼠和对照小鼠中提纯角蛋白来检测分化标记，如角蛋白。SDS-PAGE显示野生型表皮中含有K1、K5、K10和K14，而转基因小鼠皮肤中含有K1、K5、K10、K14、K6和K16。这些角蛋白的异常表达与牛皮癣皮肤相似。用单特异性抗角蛋白抗体进行免疫荧光检测角蛋白的表达。在正常小鼠中，K5/K14仅在基底层表达，而K1/K10在基底层以上表达。在转基因小鼠皮肤中，K5/K14在基底细胞层表达，在基底细胞层之上表达。K5/K14在基底细胞层以上两层表达。这些角蛋白的表达模式与银屑病中观察到的相同。镜下可见皮肤基底膜带处马氏层变薄，网脊形成疏松。这些显微表型与已知的人类皮肤病不同。

Ichtyosis and psoriasis are the most common skin diseases with charactaristic clinical features of hyperkeratosis or keratosis. There is no define animal models for these diseases. Retinoic acid or its derivative, retinoids, are commonly used as a therapeutic drug, whereas there is no drug estimation model in animals in the meanings of animal model of the diseases. Our aid is a construction of transgenic mice with tissue specific expression of a point mutated retinoic acid receptor which has dominant-negative effect to the endogenous retinoic acid receptors. We constructed the plasmid vector with K14 promoter ligated to point mutated retinoic acid receptor cDNA.The resultant transgenic mice showed a epidermal specific expression of a point mutated retinoic acid receptor. Differentiation markers, such as keratins, are examined by purifying keratins from the transgenic mice and control mice. SDS-PAGE revealed that the wild type epidermis conatins K1, K5, K10 and K14, whereas transgenic mice skin showed K1, K5, K10, K14, K6 and K16. These abnormal expression of keratins mimics psoriasis skin. Expression pattern of keratins were examined by immunofluorescent study by using mono-specific anti-keratin antibody. In normal mice, K5/K14 are expressed only in basal cell layrs and reciprocally, K1/K10 are expessed above the basal cell layr. In the transgenic mice skin, K5/K14 are expressed on basal cell layr and one layr above the basal cell layr. K5/K14 are expressed from two layrs above the basal cell layr. These expression pattern of keratins are same to those observed in psoriasis. In the microscopic examination, the skin revealed the thinning of malpigi layr and the loose of rete ridge formation at the basement mombrane zone. These microscopic phenotype are different from those known human skin diseases.