Repression of the heat shock factor 1 transcriptional activation domain is modulated by constitutive phosphorylation
Repression of the heat shock factor 1 transcriptional activation domain is modulated by constitutive phosphorylation
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DOI：
10.1128/mcb.17.4.2107
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发表时间：
1997-04-01
影响因子：
5.3
通讯作者：
Morimoto, RI
中科院分区：
文献类型：
--
作者：
Kline, MP;Morimoto, RI
热休克转录因子1（HSF 1）在哺乳动物细胞中组成型表达，并对DNA结合和转录活性进行负调控。当暴露于热休克和其他形式的化学和生理应激时，HSF 1的这些活性被迅速诱导。在这份报告中，我们证明了组成型磷酸化的HSF1在丝氨酸残基远端的转录激活域的功能，以抑制反式激活。对嵌合GAL1-HSF1缺失和点突变体的集合进行胰蛋白酶磷酸肽分析，鉴定了包含丝氨酸残基303和307的组成性磷酸化区域。在丝氨酸303和307的磷酸化的HSF 1转录活性的调节的意义证明了瞬时转染和氯霉素乙酰转移酶报告构建的测定。而转染的野生型GAL4-HSF1嵌合体的转录活性被抑制，并通过热休克去抑制，丝氨酸303和307突变为丙氨酸导致去抑制到高水平的组成型活性。在全长HSF 1的背景下，这些丝氨酸残基的突变获得了类似的结果。这些数据表明，丝氨酸303和307的组成性磷酸化在控制温度下HSF 1转录活性的负调控中具有重要作用。
Heat shock transcription factor 1 (HSF1) is constitutively expressed in mammalian cells and negatively regulated for DNA binding and transcriptional activity. Upon exposure to heat shock and other forms of chemical and physiological stress, these activities of HSF1 are rapidly induced. In this report, we demonstrate that constitutive phosphorylation of HSF1 at serine residues distal to the transcriptional activation domain functions to repress transactivation. Tryptic phosphopeptide analysis of a collection of chimeric GAL1-HSF1 deletion and point mutants identified a region of constitutive phosphorylation encompassing serine residues 303 and 307. The significance of phosphorylation at serines 303 and 307 in the regulation of HSF1 transcriptional activity was demonstrated by transient transfection and assay of a chloramphenicol acetyltransferase reporter construct. Whereas the transfected wild-type GAL4-HSF1 chimera is repressed for transcriptional activity and derepressed by heat shock, mutation of serines 303 and 307 to alanine results in derepression to a high level of constitutive activity. Similar results were obtained with mutation of these serine residues in the context of full-length HSF1. These data reveal that constitutive phosphorylation of serines 303 and 307 has an important role in the negative regulation of HSF1 transcriptional activity at control temperatures.