FK506-binding protein 51 regulates nuclear transport of the glucocorticoid receptor β and glucocorticoid responsiveness
FK506-binding protein 51 regulates nuclear transport of the glucocorticoid receptor β and glucocorticoid responsiveness
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DOI：
10.1167/iovs.07-1279
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发表时间：
2008-03-01
影响因子：
4.4
通讯作者：
Yorio, Thomas
中科院分区：
文献类型：
--
作者：
Zhang, Xinyu;Clark, Abbot F.;Yorio, Thomas
目的。人类糖皮质激素受体 GR beta 的剪接变体与青光眼中的糖皮质激素反应有关。 FK506 结合亲免素 FKBP51 的过度表达也会导致糖皮质激素抵抗的普遍状态。在本研究中，研究了 FKBP51 在 GR β 核转运和糖皮质激素反应性中的作用。用地塞米松 (DEX) 和 FK506 处理人小梁网细胞（GTM3 和 TM5）和 HeLa 细胞，并用 GR beta 和 FKBP51 表达载体转染。进行免疫共沉淀和蛋白质印迹分析以研究 FKBP51 和 FKBP52 与 GR α、GR β、Hsp90 或动力蛋白的相互作用。用 GRE 荧光素酶报告基因转染细胞，以评估 DEX 和 FK506 以及 GR beta 和 FKBP51 过表达对糖皮质激素介导的基因表达的影响。结果。在没有配体的情况下，FKBP51 参与 GR α 和 GR β 的组成型核转运。 FKBP52 似乎单独负责配体激活的 GR α 的核转运。 DEX 刺激 GR α 的易位，但不刺激 GR β 的易位。 HeLa 细胞中 GR beta 或 FKBP51 的过度表达会刺激 GR beta 易位并减少 DEX 诱导的荧光素酶。 FK506 不会改变 DEX 诱导的 GR α 易位。然而，FK506 增加了 FKBP51 与 GR beta 的关联，并在正常 TM 细胞中刺激 DEX 诱导的 GR beta 易位，但在青光眼 TM 细胞中则不然。核 GR beta 的增加显着抑制 TM 细胞中的糖皮质激素反应。结论。 GR beta 的核转运代表了 FKBP51 改变 GC 敏感性的一种新机制。 GR beta 和 FKBP51 可能是类固醇引起的高眼压个体以及青光眼患者反应性增加的原因。
PURPOSE. A spliced variant of the human glucocorticoid receptor GR beta has been implicated in glucocorticoid responsiveness in glaucoma. Over-expression of the FK506-binding immunophilin FKBP51 also causes a generalized state of glucocorticoid resistance. In the present study, the roles of FKBP51 in the nuclear transport of GR beta and glucocorticoid responsiveness were investigated.METHODS. Human trabecular meshwork cells (GTM3 and TM5) and HeLa cells were treated with dexamethasone (DEX) and FK506 and transfected with GR beta and FKBP51 expression vectors. Coimmunoprecipitation and Western blot analyses were performed to study interactions of FKBP51 and FKBP52 with GR alpha, GR beta, Hsp90, or dynein. The cells were transfected with a GRE-luciferase reporter to evaluate the effects of DEX and FK506 and the overexpression of GR beta and FKBP51 on glucocorticoidmediated gene expression.RESULTS. FKBP51 was involved in constitutive nuclear transport of both GR alpha and -beta in the absence of ligands. FKBP52 appeared to be solely responsible for the nuclear transport of ligand-activated GR alpha. DEX stimulated the translocation of GR alpha but not GR beta. Overexpression of either GR beta or FKBP51 stimulated GR beta translocation and reduced DEX-induced luciferase in HeLa cells. FK506 did not alter DEX-induced translocation of GR alpha. However, FK506 increased the association of FKBP51 with GR beta and stimulated DEX-induced translocation of GR beta in normal TM cells, but not in glaucoma TM cells. Increased nuclear GR beta significantly inhibited glucocorticoid responsiveness in TM cells.CONCLUSIONS. Nuclear transport of GR beta represents a novel mechanism through which FKBP51 alters GC sensitivity. GR beta and FKBP51 may be responsible for increased responsiveness in steroid-induced ocular hypertensive individuals as well as in patients with glaucoma.