Delfino Domenico Vittorio, Agostini Massimiliano, Spinicelli Stefania, Vito Pasquale, Riccardi Carlo
Section of Pharmacology, Department of Clinical and Experimental Medicine, University of Perugia, Via del Giochetto, 06122 Perugia, Italy.
Blood. 2004 Dec 15;104(13):4134-41. doi: 10.1182/blood-2004-03-0920. Epub 2004 Aug 19.
Glucocorticoids promote thymocyte apoptosis and modulate transcription of numerous genes. GILZ (glucocorticoid-induced leucine zipper), being one of them, is strongly up-regulated in the thymus. To elucidate its function we generated transgenic mice overexpressing it specifically in the T-cell lineage and characterized its influence on thymus function. In young adult transgenic mice CD4(+)CD8(+) thymocyte number was significantly decreased and ex vivo thymocyte apoptosis was increased. Apoptotic pathway analysis detected reduced antiapoptotic B-cell leukemia XL (Bcl-xL) expression and increased activation of caspase-8 and caspase-3. Time-course experiments showed that in wild-type (WT) thymocytes GILZ up-regulation was followed by sequential Bcl-xL decreased expression and activation of caspase-8 and of caspase-3. Moreover, GILZ delivered inside WT thymocytes by a fusion protein with the transactivator of transcription (TAT) peptide decreased Bcl-xL and promoted their apoptosis. In aged mice perturbation of thymic subset numbers was amplified over time, as demonstrated by a further decrease in CD4(+)CD8(+) cells and increases in CD4(+)CD8(-), CD4(-)CD8(-), and CD8(+)CD4(-) cell counts. These results support the hypothesis that GILZ participates in the regulation of thymocyte apoptosis by glucocorticoids.
糖皮质激素可促进胸腺细胞凋亡并调节众多基因的转录。糖皮质激素诱导亮氨酸拉链蛋白（GILZ）就是其中之一，它在胸腺中被强烈上调。为阐明其功能，我们构建了在T细胞谱系中特异性过表达GILZ的转基因小鼠，并表征其对胸腺功能的影响。在年轻成年转基因小鼠中，CD4(+)CD8(+)胸腺细胞数量显著减少，体外胸腺细胞凋亡增加。凋亡途径分析检测到抗凋亡蛋白B细胞淋巴瘤-超大蛋白（Bcl-xL）表达降低，以及半胱天冬酶-8和半胱天冬酶-3的激活增加。时间进程实验表明，在野生型（WT）胸腺细胞中，GILZ上调后依次出现Bcl-xL表达降低以及半胱天冬酶-8和半胱天冬酶-3的激活。此外，通过与转录反式激活因子（TAT）肽的融合蛋白递送至WT胸腺细胞内的GILZ降低了Bcl-xL并促进了它们的凋亡。在老年小鼠中，胸腺亚群数量的扰动随时间加剧，表现为CD4(+)CD8(+)细胞进一步减少，以及CD4(+)CD8(-)、CD4(-)CD8(-)和CD8(+)CD4(-)细胞计数增加。这些结果支持了GILZ参与糖皮质激素对胸腺细胞凋亡调节的假说。
