Evidence for NL1-independent nuclear translocation of the mineralocorticoid receptor.
Evidence for NL1-independent nuclear translocation of the mineralocorticoid receptor.
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盐皮质激素受体 NL1 独立核易位的证据。
DOI：
10.1021/bi0621819
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发表时间：
2007
期刊：
影响因子：
2.9
通讯作者：
Galigniana,MarioD
中科院分区：
文献类型：
--
作者：
PiwienPilipuk,Graciela;Vinson,GavinP;Sanchez,CelsoGomez;Galigniana,MarioD
在没有激素的情况下，皮质类固醇受体主要位于细胞质中，并且它们在配体结合后在细胞核中迅速积累（t0.5= 5 min）。一般认为，热休克蛋白90与受体的解离是允许其核转位的绝对要求。然而，最近的证据表明，热休克蛋白90可能仍然与糖皮质激素受体在此过程中，因此，受体核定位信号（NLS）不会被它的存在掩盖。为了确定盐皮质激素受体（MR）核转运的要求，首先表明在大鼠肾集合管细胞中，在醛固酮存在下，MR的核定位在10 min内完成。尽管hsp90抑制剂根赤霉素延迟了核转位，但在较长的孵育时间（t0.5= 30−40 min）内，它并不能阻止MR的完全核积聚。MR氨甲酰化产生非类固醇转化的受体，与天然MR相反，其在无细胞系统中非常稳定。与醛固酮转化的MR的完全核转位相反，在毛地黄皂苷透化的细胞中，即使其NLS暴露，也只有一小部分氨甲酰化的MR成为核。此外，虽然透化细胞与NL1肽或抗NL1抗体预孵育完全抑制NL1标记的白蛋白的核转位，但两种治疗都不能完全抑制MR核转位。我们推测，至少有两种可能的机制MR核转位。其中之一是热休克蛋白90和NL1依赖，和其他功能的方式是独立的经典途径。
In the absence of hormone, corticosteroid receptors are primarily located in the cytoplasm, and they rapidly accumulate in the nucleus (t0.5= 5 min) upon ligand binding. It is generally believed that the dissociation of hsp90 from the receptor is an absolute requirement for allowing its nuclear translocation. However, recent evidence suggests that hsp90 may remain associated with the glucocorticoid receptor during this process, and thus, the receptor nuclear localization signal (NLS) is not obscured by its presence. To determine the requirements for mineralocorticoid receptor (MR) nuclear transport, it was first shown that in rat kidney collecting duct cells, nuclear localization of MR in the presence of aldosterone was complete in 10 min. Although the hsp90 inhibitor radicicol delayed nuclear translocation, it did not prevent complete nuclear accumulation of MR at longer incubation times (t0.5= 30−40 min). MR carbamylation generates a non-steroid-transformed receptor that, in contrast to native MR, is very stable in cell-free systems. In contrast to the full nuclear translocation of aldosterone-transformed MR, only a fraction of the carbamylated MR became nuclear in digitonin-permeabilized cells even though its NLS is exposed. Furthermore, while preincubation of permeabilized cells with NL1 peptide or anti-NL1 antibody fully inhibited the nuclear translocation of NL1-tagged albumin, neither treatment fully inhibited MR nuclear translocation. We postulate that there are at least two possible mechanisms for MR nuclear translocation. One of them is hsp90- and NL1-dependent, and the other functions in a manner that is independent of the classical pathway.