PROTEIN PHOSPHATASE TYPES-1 AND OR 2A REGULATE NUCLEOCYTOPLASMIC SHUTTLING OF GLUCOCORTICOID RECEPTORS
PROTEIN PHOSPHATASE TYPES-1 AND OR 2A REGULATE NUCLEOCYTOPLASMIC SHUTTLING OF GLUCOCORTICOID RECEPTORS
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DOI：
10.1210/mend-5-9-1215
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发表时间：
1991-09-01
影响因子：
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通讯作者：
BRAUTIGAN, DL
中科院分区：
文献类型：
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作者：
DEFRANCO, DB;QI, M;BRAUTIGAN, DL
我们已经使用冈田酸（OA），丝氨酸/苏氨酸蛋白磷酸酶1型（PP-1）和2A型（PP-2A）的细胞渗透性抑制剂，证明糖皮质激素受体（GR）在大鼠成纤维细胞的亚细胞分布受其磷酸化状态的影响。 OA处理的细胞中的核GR保留转录增强活性。 激素激动剂结合GR的核输入或输出不受OA的影响。 然而，完全抑制PP-2A并部分抑制PP-1的OA剂量，而不是仅部分抑制PP-2A的较低剂量，导致激动剂结合的GR的无效核保留，以及它们重新分布到细胞质中。 这些受体似乎被困在细胞质区室中，不能再循环（即重新进入细胞核）。 在GR再循环的不同步骤期间添加OA表明，在GR的核输出期间必须存在OA以阻止GR再循环。 PP-1和/或PP-2A在GR再循环中的直接作用通过在OA抑制再循环期间体内GR的位点特异性过度磷酸化来提出。 这些是通过PP-1和PP-2A进行体外位点特异性去磷酸化的相同位点。 抑制PP-1和/或PP-2A导致的GR再循环的阻断类似于先前在v-mos转化的大鼠成纤维细胞中观察到的作用。 有趣的是，OA抑制PP-2A在v-mos-转化细胞导致逆转癌蛋白对GR再循环和保留在核隔室内的受体的影响。 我们建议，GR回收的影响，不同的蛋白磷酸酶（PP-1和/或PP-2A）的活动，并在V-MOS转化细胞中观察到的这一途径的干扰可能是磷酸酶或其目标的一个特定的子集上的癌蛋白的影响的结果。
We have used okadaic acid (OA), a cell-permeable inhibitor of serine/threonine protein phosphatase types 1 (PP-1) and 2A (PP-2A), to demonstrate that the subcellular distribution of glucocorticoid receptor (GR) in rat fibroblasts is influenced by its phosphorylation state. Nuclear GRs in OA-treated cells retain transcriptional enhancement activity. Nuclear import or export of hormone agonist-bound GRs is not affected by OA. However, a dose of OA that fully inhibits PP-2A and partially inhibits PP-1, but not a lower dose that only partially inhibits PP-2A, leads to inefficient nuclear retention of agonist-bound GRs, and their redistribution into the cytoplasm. These receptors appear to be trapped in the cytoplasmic compartment and are unable to recycle (i.e. reenter the nucleus). Addition of OA during different steps of GR recycling demonstrates that OA must be present during nuclear export of GRs to block GR recycling. A direct role for PP-1 and/or PP-2A in GR recycling is suggested by site-specific hyperphosphorylation of GRs in vivo during OA inhibition of recycling. These are the same sites that undergo in vitro site-specific dephosphorylation by PP-1 and PP-2A. The block in GR recycling that results from inhibition of PP-1 and/or PP-2A resembles effects previously observed in v-mos-transformed rat fibroblasts. Interestingly, OA inhibition of PP-2A in v-mos-transformed cells leads to the reversal of oncoprotein effects on GR recycling and retention of receptors within the nuclear compartment. We propose that GR recycling is influenced by the activities of distinct protein phosphatases (PP-1 and/or PP-2A), and that the interference of this pathway observed in v-mos-transformed cells may be the result of effects of the oncoprotein on the phosphatases or a specific subset of their targets.