PROTEIN PHOSPHATASE-1 AND PHOSPHATASE-2A REGULATE THE TRANSCRIPTIONAL AND DNA-BINDING ACTIVITIES OF RETINOIC ACID RECEPTORS
PROTEIN PHOSPHATASE-1 AND PHOSPHATASE-2A REGULATE THE TRANSCRIPTIONAL AND DNA-BINDING ACTIVITIES OF RETINOIC ACID RECEPTORS
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DOI：
10.1074/jbc.270.18.10806
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发表时间：
1995-05-05
影响因子：
4.8
通讯作者：
FORMSTECHER, P
中科院分区：
文献类型：
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作者：
LEFEBVRE, P;GAUB, MP;FORMSTECHER, P
为了确定哪些因素可以调节视黄酸受体（RAR和RXR）的DNA结合和转录特性，我们研究了具有各种视黄酸反应元件（RARE）的报告基因对蛋白磷酸酶（PPases）抑制的敏感性。通过冈田酸抑制PPases导致报告基因活性以RARE依赖和配体非依赖的方式增加，并且依赖于所使用的响应元件的类型。蛋白磷酸酶2A和1（PP 2A和PP 1）的过表达降低了所测试的报告基因的诱导。冈田酸处理的COS细胞的核提取物在体外显示2-5倍的受体结合RARE的水平增加，表明PPases抑制增加了类维生素A受体的DNA结合活性。用碱性磷酸酶和部分纯化的PP 1和PP 2A处理从COS细胞中提取的受体，使它们的DNA结合活性降低，但与DNA结合的异二聚体对磷酸酶处理不敏感。重组实验表明，两种受体的磷酸化增加了RXR/RAR异二聚体的DNA结合活性。总之，这些数据表明RAR和RXR的磷酸化状态的调节代表了类维生素A信号传导途径的另一个调节水平。
To determine which factors may regulate the DNA binding and transcriptional properties of retinoic acid receptors (RARs and RXRs), we investigated the sensitivity of reporter genes bearing various retinoic acid response elements (RAREs) to protein phosphatases (PPases) inhibition. PPases inhibition by okadaic acid led to an increase of the reporter genes activity in a RARE-dependent and ligand-independent manner and was dependent on the type of response element used. Overexpression of protein phosphatases 2A and 1 (PP2A and PP1) decreased the inducibility of the reporter genes tested. Nuclear extracts from okadaic acid-treated COS cells displayed an 2-5-fold increased level of receptor binding to RAREs in vitro, suggesting that PPases inhibition increased the DNA binding activity of retinoid receptors. Treatment of receptors extracted from COS cells by alkaline phosphatase and partially purified PP1 and PP2A decreased their DNA binding activity, but heterodimers bound to DNA were not sensitive to phosphatase treatment. Reconstitution experiments showed that phosphorylation of both receptors increased the DNA binding activity of RXR/RAR heterodimers. Taken together, these data show that the modulation of the phosphorylation state of RARs and RXRs represents an other level of regulation of the retinoid signaling pathway.