Protein phosphatase 5 is a negative regulator of estrogen receptor-mediated transcription
Protein phosphatase 5 is a negative regulator of estrogen receptor-mediated transcription
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DOI：
10.1210/me.2003-0308
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发表时间：
2004-05-01
影响因子：
--
通讯作者：
Inoue, S
中科院分区：
文献类型：
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作者：
Ikeda, K;Ogawa, S;Inoue, S
雌激素受体（ER）是可以通过雌激素依赖性和生长因子依赖性磷酸化来调节的转录因子。酵母双杂交筛选鉴定出丝氨酸/苏氨酸蛋白磷酸酶 (PP5) 是 ERbeta (1 - 481)（一种显性失活 ERbeta 突变体）的相互作用物。谷胱甘肽 S-转移酶下拉测定、哺乳动物双杂交测定和免疫沉淀研究表明，PP5 通过其四肽重复结构域直接结合 ERα 和 ERβ。 ERα 和 ERβ 的 E 结构域（不包含转录激活功能 2 中的激活结构域核心区域）是与 PP5 结合所必需的。在ERα阳性乳腺癌MCF7细胞中，ERα在丝氨酸残基118（受体的主要磷酸化位点）上的雌激素和表皮生长因子依赖性磷酸化通过表达PP5而减少，但通过PP5反义寡核苷酸增强。雌激素诱导的 ERα 和 ERβ 转录活性以及雌激素响应基因（包括 pS2、c-myc 和细胞周期蛋白 D1）的 mRNA 表达被 PP5 抑制，但被 PP5 反义寡核苷酸增强。仅由四肽重复结构域组成的截短 PP5 突变体充当显性失活 PP5，增强 ERα 的丝氨酸残基 118 磷酸化以及 ERα 和 ERβ 的反式激活。我们提出了第一个证据表明 PP5 在体内作为 ER 磷酸化和转录激活的抑制调节剂发挥作用。
Estrogen receptors (ERs) are transcription factors that can be modulated by both estrogen-dependent and growth factor-dependent phosphorylation. A yeast two-hybrid screening identified a serine/ threonine protein phosphatase (PP5) as an interactant of ERbeta ( 1 - 481), a dominant negative ERbeta mutant. Glutathione S-transferase pull-down assays, mammalian two-hybrid assays, and immunoprecipitation studies showed that PP5 directly binds to both ERalpha and ERbeta via its tetratricopeptide repeat domain. E domains of ERalpha and ERbeta, without containing activation domain core regions in transcription activation function 2, were required for the binding to PP5. In ERalpha-positive breast cancer MCF7 cells, estrogen- and epidermal growth factor-dependent phosphorylation of ERalpha on serine residue 118, a major phosphorylation site of the receptor, was reduced by expressing PP5 but enhanced by PP5 antisense oligonucleotide. Estrogen-induced transcriptional activities of both ERalpha and ERbeta and mRNA expression of estrogen-responsive genes, including pS2, c-myc, and cyclin D1, were suppressed by PP5 but enhanced by PP5 antisense oligonucleotide. A truncated PP5 mutant consisting only of its tetratricopeptide repeat domain acted as a dominant negative PP5 that enhanced serine residue 118 phosphorylation of ERalpha and transactivations by ERalpha and ERbeta. We present the first evidence that PP5 functions as an inhibitory regulator of ER phosphorylation and transcriptional activation in vivo.