FK506 binding to the 56-kilodalton immunophilin (Hsp56) in the glucocorticoid receptor heterocomplex has no effect on receptor folding or function.
FK506 binding to the 56-kilodalton immunophilin (Hsp56) in the glucocorticoid receptor heterocomplex has no effect on receptor folding or function.
复制标题
FK506 与糖皮质激素受体杂复合物中的 56 千道尔顿亲免素 (Hsp56) 结合，对受体折叠或功能没有影响。
DOI：
10.1021/bi00066a015
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发表时间：
1993
期刊：
影响因子：
2.9
通讯作者：
Pratt,WB
中科院分区：
文献类型：
--
作者：
Hutchison,KA;Scherrer,LC;Czar,MJ;Ning,Y;Sanchez,ER;Leach,KL;DeibelJr,MR;Pratt,WB
最近有报道糖皮质激素受体异源复合物的hsp 56组分是FK 506结合类的亲免蛋白[Yem，A. W;，Tomasselli，A. G.，Heinrikson，RL，Escher-Neely，H.，拉夫，弗吉尼亚州，约翰逊河A.、& Deibel，M. R.（1992）J.Biol.Chem.267，2868-2871; Tai，P.K.，阿尔伯斯，M. W.，张，H.，费伯湖E、& Schreiber，S. L.（1992）Science 256，1315-1318]。在同一分子复合物中存在这两种有效免疫抑制剂的结合蛋白，这迫使我们问FK 506是否影响糖皮质激素受体功能。我们在这里表明，热休克蛋白56是一个组成部分的天然L-细胞糖皮质激素受体异源复合物和[3 H] FK 506结合的免疫纯化，未转化的受体复合物。然而，当FK 506的浓度超过占据hsp 56上所有结合位点所需的浓度时，FK 506不影响受体的类固醇结合活性，也不稳定或解离受体-hsp 90复合物。FK 506不影响类固醇介导的hsp 90与受体的体外解离，也不影响类固醇介导的受体核转移或类固醇介导的完整细胞中报告基因的转录增强。当免疫纯化的小鼠糖皮质激素受体通过兔网织红细胞裂解物重建成热休克蛋白复合物时，除了hsp 90和hsp 70之外，hsp 56也存在于重建的复合物中。然而，FK 506不影响复合物的重建或受体恢复到类固醇结合状态，这是受体与hsp 90结合时发生的构象变化。虽然糖皮质激素受体和FK 506亲免素在同一异分子复合物中的存在确实是令人激动的，但在分子水平上既没有观察到FK 506对糖皮质激素受体功能的增强也没有观察到抑制。在完整的细胞中，认为受体保持与该热休克蛋白复合物对接，直到类固醇的结合触发它们从hsp 90解离并进展到高亲和力的核结合位点，在那里发生转录激活中的主要事件。当制备的抗部分纯化的、稳定的兔孕激素受体的单克隆抗体（KN 382/EC 1）与子宫胞液中的~ 59-kDa非类固醇结合蛋白反应时，发现了异源复合物中的hsp 56组分，
Revised Manuscript Received January 13, 1993 abstract: It has recently been reported that the hsp56 component of glucocorticoidreceptor heterocomplexes is an immunophilin of the FK506 binding class [Yem, A. W;, Tomasselli, A. G., Heinrikson, RL, Zurcher-Neely, H., Ruff, V. A., Johnson, R. A., & Deibel, M. R.(1992) J. Biol. Chem. 267, 2868-2871; Tai, P. K., Albers, M. W., Chang, H., Faber, L. E., & Schreiber, S. L.(1992) Science 256, 1315-1318]. The existence of binding proteins for these two potent groups of immunosuppressants in the same molecular complex compels us to ask whether FK506 affects glucocorticoid receptor function. We show here that hsp56 is a component of the native L-cell glucocorticoid receptor heterocomplex and that [3H] FK506 binds to the immunopurified, untransformed receptor complex. However, at concentrations in excess of those required to occupy allof its binding sites on hsp56, FK506 does not affect the steroid binding activity of the receptor nor does it stabilize or dissociate the receptor-hsp90 complex. FK506 does not affect steroid-mediated hsp90 dissociation from the receptor in vitro, and it does not affect steroid-mediated nuclear transfer of the receptor or steroid-mediated transcriptional enhancement from a reporter in intact cells. When immunopurified mouse glucocorticoid receptor is reconstituted into a heat shock protein complex by rabbit reticulocyte lysate, hsp56 is present in the reconstituted complexin addition to hsp90 and hsp70. FK506, however, does not affect reconstitution of the complex or return of the receptor to the steroid binding state, a efaarige of conformation that occurs upon receptor association with hsp90. Although the existence of the glucocorticoid receptor and the FK506 immunophilin in the same heteromolecular complex is indeed provocative, neither enhancement nor inhibition of glucocorticoid receptor function by FK506 is observed at the molecular level.Steroid receptors are recovered from hormone-free cells in association with hsp90,'hsp56, and in some cases hsp70 [see Pratt (1990) for a review]. In intact cells, it is thought that the receptors remain docked to this heat shock protein complex until binding of steroid triggers their dissociation from hsp90 and their progression to high-affinity nuclear binding sites where the primary events in transcriptional activation occur. The hsp56 component of the heterocomplex was discovered when a monoclonal antibody (KN 382/EC1) prepared against the partially-purified, molybdate-stabilized, rabbit progest-erone receptor was found to react with a non-steroid binding~ 59-kDa protein in uterine cytosol, but also to cause