25 hydroxyvitamin D 1 α-hydroxylase is required for optimal epidermal differentiation and permeability barrier homeostasis
25 hydroxyvitamin D 1 α-hydroxylase is required for optimal epidermal differentiation and permeability barrier homeostasis
复制标题
DOI：
10.1111/j.0022-202x.2004.22424.x
复制
发表时间：
2004-04-01
影响因子：
6.5
通讯作者：
Elias, PM
中科院分区：
文献类型：
--
作者：
Bikle, DD;Chang, S;Elias, PM
角质形成细胞表达高水平的25 OHD 1 α-羟化酶（1 OHase）。该酶的产物1，25-二羟维生素D（1，25（OH）（2）D）在体外促进角质形成细胞的分化，表明该酶在表皮分化中的重要作用。为了测试1 α OHase活性是否是体内角质形成细胞分化所必需的，我们检查了1 α OHase基因表达缺失的小鼠（1 α OHase（-/-））的分化过程。培育缺失等位基因的杂合子，并通过PCR对后代进行基因分型。通过光镜和电子显微镜水平的组织学、分化标志物的免疫细胞化学以及使用经表皮失水（TEWL）检查渗透性屏障的功能，检查1 α OHase（-/-）动物及其野生型同窝仔（1 α OHase（+/+））的表皮。没有观察到肉眼可见的表皮表型;然而，表皮的免疫细胞化学评估显示，外皮蛋白、聚丝蛋白和兜甲蛋白-角质形成细胞分化的标志物减少，这对角质形成膜的形成至关重要。这些观察结果在电子显微镜水平得到证实，其显示F（含有聚丝蛋白）和L（含有兜甲蛋白）颗粒减少，钙梯度降低。使用TEWL测试这些观察结果的功能意义，以评估表皮的渗透屏障功能。尽管TEWL在基础状态下是正常的，但在使用胶带剥离破坏屏障后，1alphaOHase（-/-）动物显示出正常屏障功能的恢复明显延迟。这种延迟与板层体分泌减少和表皮钙梯度改革失败有关。因此，25 OHD 1 OHase是正常表皮分化所必需的，最有可能是通过产生维生素D代谢物1，25（OH）（2）D，负责诱导调节表皮中钙水平的蛋白质，这对屏障的产生和维持至关重要。
Keratinocytes express high levels of 25OHD 1alpha-hydroxylase (1OHase). The product of this enzyme, 1,25-dihydroxyvitamin D (1,25(OH)(2)D), promotes the differentiation of keratinocytes in vitro suggesting an important role for this enzyme in epidermal differentiation. To test whether 1OHase activity is essential for keratinocyte differentiation in vivo we examined the differentiation process in mice null for the expression of the 1alphaOHase gene (1alphaOHase(-/-)) Heterozygotes for the null allele were bred, and the progeny genotyped by PCR. The epidermis of the 1alphaOHase(-/-) animals and their wild-type littermates (1alphaOHase(+/+)) were examined by histology at the light and electron microscopic level, by immunocytochemistry for markers of differentiation, and by function examining the permeability barrier using transepidermal water loss (TEWL). No gross epidermal phenotype was observed; however, immunocytochemical assessment of the epidermis revealed a reduction in involucrin, filaggrin, and loricrin-markers of differentiation in the keratinocyte and critical for the formation of the cornified envelope. These observations were confirmed at the electron microscopic level, which showed a reduction in the F (containing filaggrin) and L (containing loricrin) granules and a reduced calcium gradient. The functional significance of these observations was tested using TEWL to evaluate the permeability barrier function of the epidermis. Although TEWL was normal in the basal state, following disruption of the barrier using tape stripping, the 1alphaOHase(-/-) animals displayed a markedly delayed recovery of normal barrier function. This delay was associated with a reduction in lamellar body secretion and a failure to reform the epidermal calcium gradient. Thus, the 25OHD 1OHase is essential for normal epidermal differentiation, most likely by producing the vitamin D metabolite, 1,25(OH)(2)D, responsible for inducing the proteins regulating calcium levels in the epidermis that are critical for the generation and maintenance of the barrier.