Zoppi N, Ghinelli A, Gardella R, Barlati S, Colombi M
Division of Biology and Genetics, Department of Biomedical Sciences and Biotechnology, University of Brescia, Brescia, Italy.
Cell Biol Int. 1998;22(7-8):499-508. doi: 10.1006/cbir.1998.0283.
The effect of dexamethasone (DEX) on the expression of fibronectin (FN), proalpha(1)(I) collagen (Col1), integrin alpha(2), alpha(5)and beta(1)subunits mRNAs, were studied by quantitative in situ hybridization (ISH) with radiolabelled probes in relationship with the organization of the extracellular matrix (ECM) of FN in human skin fibroblasts. In particular, two fibroblast strains were analysed, one derived from a control donor, typically organizing a rich ECM of FN, and the other from a patient affected by Ehlers-Danlos syndrome (EDS), which did not assemble the FN-ECM. Treatment of both fibroblast strains with 10(-7) m DEX slightly enhanced the level of FN mRNA (by about 1.5-fold), did not influence the level of alpha(5)subunit mRNA and reduced Col1, alpha(2)and beta(1)integrin subunits mRNAs by 2-3-fold. These results show that, in these cells, DEX coordinately downregulates the expression of Col1 and its specific integrin alpha(2)beta(1). Moreover, DEX regulates in a different manner the alpha(5)and beta(1)subunits forming the main FN receptor (FNR) in skin fibroblasts. Immunofluorescence microscopy evidencing the FN-ECM and integrins containing alpha(5)and beta(1)subunits showed that in control cells DEX induced a slight enhancement of the FN-ECM and of the alpha(5)beta(1)receptors patches. Therefore, in these cells the decrease of beta(1)FN receptor subunit mRNA, as well as the decrease of Col1 and its receptor mRNAs, did not influence the FN-ECM assembly. In EDS fibroblasts, DEX decreased the cytoplasmic accumulation of FN and induced the assembly of a rich FN-ECM through the formation of large FNR integrin patches, codistributing with the FN-ECM. We suggest that in EDS skin fibroblasts DEX corrects the defective FN-ECM favouring the sorting and the organization of FN and its alpha(5)beta(1)integrin receptor.
通过使用放射性标记探针的定量原位杂交（ISH）技术，研究了地塞米松（DEX）对人皮肤成纤维细胞中纤连蛋白（FN）、原α1（I）型胶原蛋白（Col1）、整合素α2、α5和β1亚基mRNA表达的影响，并探讨了其与FN细胞外基质（ECM）组织的关系。特别分析了两种成纤维细胞系，一种来自对照供体，通常能形成丰富的FN-ECM；另一种来自患有埃勒斯-当洛综合征（EDS）的患者，该细胞系无法组装FN-ECM。用10^(-7) m DEX处理这两种成纤维细胞系，均使FN mRNA水平略有升高（约1.5倍），对α5亚基mRNA水平无影响，而使Col1、α2和β1整合素亚基mRNA水平降低2-3倍。这些结果表明，在这些细胞中，DEX协同下调Col1及其特异性整合素α2β1的表达。此外，DEX以不同方式调节皮肤成纤维细胞中构成主要FN受体（FNR）的α5和β1亚基。免疫荧光显微镜观察FN-ECM以及含有α5和β1亚基的整合素显示，在对照细胞中，DEX使FN-ECM和α5β1受体斑块略有增加。因此，在这些细胞中，β1 FN受体亚基mRNA的减少以及Col1及其受体mRNA的减少并未影响FN-ECM的组装。在EDS成纤维细胞中，DEX减少了FN的细胞质积累，并通过形成与FN-ECM共分布的大型FNR整合素斑块诱导了丰富的FN-ECM组装。我们认为，在EDS皮肤成纤维细胞中，DEX纠正了有缺陷的FN-ECM，有利于FN及其α5β1整合素受体的分选和组织。
