GILZ mediates the antiproliferative activity of glucocorticoids by negative regulation of Ras signaling
GILZ mediates the antiproliferative activity of glucocorticoids by negative regulation of Ras signaling
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DOI：
10.1172/jci30724
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发表时间：
2007-06-01
影响因子：
15.9
通讯作者：
Riccardi, Carlo
中科院分区：
文献类型：
--
作者：
Ayroldi, Emira;Zollo, Ornella;Riccardi, Carlo
Tsc 22 d3编码糖皮质激素诱导的亮氨酸拉链（GILZ），最初被确定为地塞米松应答基因，参与控制T淋巴细胞活化和凋亡。然而，该分子的生理作用及其在糖皮质激素（GC）生物活性中的功能尚未阐明。在这里，我们表明，GILZ直接与Ras在体外和体内的相互作用，如GILZ和Ras共免疫沉淀和共定位后，PMA激活在原代小鼠脾T淋巴细胞和胸腺细胞。GILZ突变体的分析表明，它们通过结节性硬化症复合物盒（TSC）结合Ras，并根据Ras的激活水平，与Ras和Raf形成三聚体复合物;我们先前将其鉴定为GILZ结合剂。由于这些相互作用，GILZ减少了Ras和Raf下游靶点的激活，包括ERK 1/2、AKT/PKB丝氨酸/苏氨酸激酶和视网膜母细胞瘤（Rb）磷酸化和细胞周期蛋白D1表达，导致Ras和Raf-dependent细胞增殖和Ras诱导的NIH-3 T3转化的抑制。GILZ沉默导致伴刀豆球蛋白A诱导的T细胞增殖增加，最显著的是，抑制地塞米松抗增殖作用。总之，这些发现表明，GILZ作为Ras和Raf-induced增殖的负调节剂，是GC抗增殖作用的重要介质。
Tsc22d3 coding for glucocorticoid-induced leucine zipper (GILZ) was initially identified as a dexamethasone-responsive gene involved in the control of T lymphocyte activation and apoptosis. However, the physiological role of this molecule and its function in the biological activity of glucocorticoids (GCs) has not been clarified. Here, we demonstrate that GILZ interacts directly with Ras in vitro and in vivo as shown by GILZ and Ras coimmunoprecipitation and colocalization upon PMA activation in primary mouse spleen T lymphocytes and thymus cells. The analysis of GILZ mutants showed that they bound Ras through the tuberous sclerosis complex box (TSC) and, depending on the Ras activation level, formed a trimeric complex with Ras and Raf; which we previously identified as a GILZ binder. As a consequence of these interactions, GILZ diminished the activation of Ras and Raf downstream targets including ERK1/2, AKT/PKB serine/threonine kinase, and retinoblastoma (Rb) phosphorylation and cyclin D1 expression, leading to inhibition of Ras- and Raf-dependent cell proliferation and Ras-induced NIH-3T3 transformation. GILZ silencing resulted in an increase in concanavalin A-induced T cell proliferation and, most notably, inhibition of dexamethasone antiproliferative effects. Together, these findings indicate that GILZ serves as a negative regulator of Ras- and Raf-induced proliferation and is an important mediator of the antiproliferative effect of GCs.