维甲酸(RA)在上皮内稳态中起重要作用,扩散,上皮细胞的分化和通透性。小鼠角质形成细胞,K38,在血清三维(3D)培养物中重建的非角化复层上皮,含有视黄醇(RA的来源),但形态与体内上皮不同。形成的上皮很厚,细胞-细胞接触放松。这里,我们研究了RXR拮抗剂是否抑制RA受体(RAR)/类维生素AX受体(RXR)介导的信号传导,HX531在形态学和细胞间连接方面改进了K383D培养物。0.5μMHX531形成的上皮很薄,由于桥粒蛋白(DSG)-1,DSG3和斑红蛋白(PG)的层特异性分布恢复,细胞间隙变窄。此外,桥粒蛋白和紧密连接蛋白的水平,包括DSG1,DSG2,DSG3,PG,claudin(CLDN)-1和CLDN4增加,但是粘附蛋白连接蛋白,E-cadherin,没有显示任何变化。此外,CLDN1被募集到浅表细胞中的occludin阳性细胞-细胞接触,跨上皮电阻增加。因此,用0.5μMHX531处理的K383D培养物提供了有用的体外模型来研究非角化上皮中的细胞间连接。
Retinoic acid (RA) plays an important role in epithelial homeostasis and influences the morphology, proliferation, differentiation and permeability of epithelial cells. Mouse keratinocytes, K38, reconstituted non-keratinized stratified epithelium in three-dimensional (3D) cultures with serum, which contains retinol (a source of RA), but the morphology was different from in vivo epithelium. The formed epithelium was thick, with loosened cell-cell contacts. Here, we investigated whether the inhibition of RA receptor (RAR)/retinoid X receptor (RXR)-mediated signaling by an RXR antagonist, HX 531, improved K38 3D cultures in terms of morphology and intercellular junctions. The epithelium formed by 0.5 μM HX531 was thin, and the intercellular space was narrowed because of the restoration of the layer-specific distribution of desmoglein (DSG)-1, DSG3 and plakoglobin (PG). Moreover, the levels of desmosomal proteins and tight junction proteins, including DSG1, DSG2, DSG3, PG, claudin (CLDN)-1 and CLDN4 increased, but the adherens junction protein, E-cadherin, did not show any change. Furthermore, CLDN1 was recruited to occludin-positive cell-cell contacts in the superficial cells and transepithelial electrical resistance was increased. Therefore, K38 3D cultures treated with 0.5 μM HX531 provides a useful in vitro model to study intercellular junctions in the non-keratinized epithelium.