Tissue- and stratum-specific expression of the human involucrin promoter in transgenic mice.

Involucrin is a marker of keratinocyte terminal differentiation and is expressed only in the suprabasal layers of stratified squamous epithelium. In a previous study with various cell types in culture, we noted that expression of the putative human involucrin promoter was keratinocyte specific. To determine if this promoter is sufficient to direct expression to the suprabasal cells of stratified squamous epithelia in vivo, we have now generated transgenic mouse lines harboring the involucrin promoter sequences linked to a beta-galactosidase reporter gene. In the resulting lines, beta-galactosidase was expressed in the suprabasal compartment of stratified squamous epithelia and in hair follicles in a tissue-specific manner. In the palate, distinct vertical stacks of beta-galactosidase-expressing cells were present, suggesting movement of clonally derived cells through the epithelium. The involucrin gene has a single intron upstream of the translational start site, and removal of this intron did not affect tissue- or stratum-specific expression. These results show that the 3.7-kb involucrin upstream sequences contain all the information necessary for a high level of tissue- and stratum-specific expression. IMAGES:

套膜蛋白（involucrin）是角质形成细胞终末分化的标志物，仅在复层鳞状上皮的基上层中表达。既往针对体外培养的多种细胞类型开展的研究中，我们观察到推定的人类套膜蛋白启动子的表达具有角质形成细胞特异性。为明确该启动子是否足以在活体中指导复层鳞状上皮的基上层细胞表达，我们现已构建了携带有与β-半乳糖苷酶（beta-galactosidase）报告基因相连的套膜蛋白启动子序列的转基因小鼠品系。在获得的转基因品系中，β-半乳糖苷酶以组织特异性方式在复层鳞状上皮的基上层以及毛囊中表达。在腭部组织中，可见清晰的β-半乳糖苷酶阳性细胞垂直堆叠带，提示克隆源性细胞沿上皮层进行迁移。套膜蛋白基因在翻译起始位点上游存在单个内含子，移除该内含子并不会影响其组织特异性及层特异性表达。上述结果表明，3.7kb的套膜蛋白上游序列包含了实现高水平组织特异性与层特异性表达所需的全部调控信息。IMAGES: