Functional analysis and genomic mapping of corneal epithelium-specific genes and detection of disease-related genes among ocular surface disorders.

我们从角膜上皮细胞的CDNA文库中克隆了3个新基因：组织蛋白酶V、尿路蛋白1b和钙依赖氯通道(CaCl2)。组织蛋白酶V是一种在弱酸性条件下工作的半胱氨酸蛋白酶。新克隆的uroplakin 1b是已报道的3‘端序列的异构体。定位于人类染色体1p32的CaCl2在角膜上皮细胞中的表达水平是其他氯离子通道的100倍，这表明它是角膜透明所必需的。DNA芯片比较慢性S-J综合征患者和正常志愿者外周血T淋巴细胞基因表达的结果显示，hMG-1、钙调蛋白上调，铁蛋白L链和56K自身抗原Annexin X1下调。DNA芯片检测羊膜上皮细胞与正常角膜上皮细胞基因表达的结果显示，IL-6、IL-13、IL-4下调，IGF结合蛋白上调。比较干燥综合征患者和正常对照组结膜上皮细胞角蛋白6、16、SPRR2A、激肽释放蛋白7、IL-6、MIG、两性调节蛋白、人类白细胞抗原-DR、防御素β2、纤维连接蛋白和c-fos转录因子的基因表达。提示本病结膜上皮细胞有角化和细胞增殖的倾向，其原因是结膜上皮细胞严重干燥和快速周转。此外，泪液中可能分泌的干扰素-γ可诱导MIG、HLA-DR和防御素β2在本病中的表达。

We have cloned 3 novel genes from the CDNA library of corneal epithelium : cathepsin V, uroplakin 1b and calcium-dependent chloride channel (CACL2). Cathepsin V proved to be a kind of cysteine protease working on weak acid condition. Uroplakin 1b, newly cloned, is an isoform of that reported previously in the 3' end sequence. CACL2, mapped to 1p32 of human chromosome, was expressed in corneal epithelium at a 100 x higher level than the other chloride channels, suggesting that it is essential for corneal transparency.DNA chip comparison of peripheral blood T lymphocyte gene expression between chronic phase S-J syndrome patients and normal volunteers revealed up-regulation of HMG-1, calmodulin, and down-regulation of ferritin L chain and 56K autoantigen annexin X1.DNA chip measurement of gene expression between corneal epithelium cultivated on amniotic membrane and normal corneal epithelium in vivo revealed down-regulation of IL-6, IL-13, IL-4, and up-regulation of IGF-binding protein, emmprin and CD27 ligand.Comparison of gene expression on conjunctival epithelium between Sjogren's syndrome patients and normal volunteers also revealed up-regulation of cytokeratin 6, 16, SPRR2A, kallikrein7, IL-6, MIG, amphiregulin, HLA-DR, defensin beta 2, fibronectin and c-fos transcription factor in Sjogren's syndrome. These facts suggest that conjunctival epithelial cells in this disease have a tendency toward keratinization and cell proliferation, due to severe dryness and fast turnover of conjunctival epithelial cells. Also, interferon gamma, which may be secreted in tear fluid, may induce expression of MIG, HLA-DR and defensin beta 2 in this disease.