Oxysterols induce differentiation in human keratinocytes and increase Ap-1-dependent involucrin transcription
Oxysterols induce differentiation in human keratinocytes and increase Ap-1-dependent involucrin transcription
复制标题
DOI：
10.1046/j.1523-1747.2000.00895.x
复制
发表时间：
2000-03-01
影响因子：
6.5
通讯作者：
Feingold, KR
中科院分区：
文献类型：
--
作者：
Hanley, K;Ng, DC;Feingold, KR
核激素受体超家族的配体和激活剂在调节表皮发育和分化中起重要作用。先前，我们发现天然存在的脂肪酸，以及合成的过氧化物酶体增殖激活受体配体，在体外诱导角质形成细胞分化。在这里，我们询问在表皮中重新形成并激活肝脏x激活受体的另一类脂质氧甾醇是否调节角化细胞分化。在低钙条件下，25-或22r -羟胆固醇培养的正常人角质形成细胞中，分化标记物天花素和转谷氨酰胺酶1的mRNA和蛋白水平增加了2- 3倍。在高钙单独诱导分化的情况下，氧化甾醇进一步提高了mRNA水平。作为终末分化指标的锥形包膜形成率，也在氧甾醇处理下增加了2倍。相反，DNA合成速率被氧化甾醇抑制了约50%。在转染转谷氨酰胺酶1或天合蛋白启动子-荧光素酶构建体的角质形成细胞中评估转录调节。22r -羟胆固醇使转谷氨酰胺酶1和天花苷启动子活性增加2- 3倍。天花素启动子-2452 bp至-1880 bp区域的缺失，或该区域内AP-1位点的突变，都消除了氧甾醇反应性。此外，通过凝胶移位分析，在氧化甾醇处理的角质形成细胞中观察到AP-1 DNA结合增加。最后，我们证明了肝脏x激活受体α和β mrna的存在，并表明氧化甾醇刺激肝脏x激活受体反应元件转染到角质形成细胞。这些数据表明，氧化甾醇诱导角化细胞分化，部分是通过增加ap -1依赖性天花素基因的转录，这种作用可能是由肝脏x激活受体介导的。
Ligands and activators of the nuclear hormone receptor superfamily are important in the regulation of epidermal development and differentiation. Previously, we showed that naturally occurring fatty acids, as well as synthetic ligands for the peroxisome proliferator-activated receptor, induce keratinocyte differentiation in vitro. Here we asked whether oxysterols, another class of lipids formed de novo in the epidermis and that activate liver X-activated receptor, regulate keratinocyte differentiation. mRNA and protein levels of involucrin and transglutaminase 1, markers of differentiation, increased 2- to 3-fold in normal human keratinocytes incubated in the presence of 25- or 22R-hydroxycholesterol in low calcium. In high calcium, which alone induces differentiation, mRNA levels were further increased by oxysterols. Rates of cornified envelope formation, an indicator of terminal differentiation, also increased 2-fold with oxysterol treatment. In contrast, the rate of DNA synthesis was inhibited approximately 50% by oxysterols. Transcriptional regulation was assessed in keratinocytes transfected with either transglutaminase 1 or involucrin promoter-luciferase constructs. 22R-hydroxycholesterol increased transglutaminase 1 and involucrin promoter activity 2- to 3-fold. Either deletion of the -2452 bp to -1880 bp region of the involucrin promoter, or mutation of the AP-1 site within this region, abolished oxysterol responsiveness. Moreover, increased AP-1 DNA binding was observed in oxysterol-treated keratinocytes by gel shift analyses. Finally, we demonstrated the presence of liver X-activated receptor alpha and beta mRNAs, and showed that oxysterols stimulate a liver X-activated receptor response element transfected into keratinocytes. These data suggest that oxysterols induce keratinocyte differentiation, in part through increased AP-1-dependent transcription of the involucrin gene, an effect that may be mediated by liver X-activated receptor.