Requirement of Ca2+ and CaMKII for Stat1 Ser-727 phosphorylation in response to IFN-γ
Requirement of Ca2+ and CaMKII for Stat1 Ser-727 phosphorylation in response to IFN-γ
复制标题
DOI：
10.1073/pnas.052159099
复制
发表时间：
2002-04-30
影响因子：
11.1
通讯作者：
Zhang, JJ
中科院分区：
文献类型：
--
作者：
Nair, JS;DaFonseca, CJ;Zhang, JJ
在对ifn - γ的反应中，潜伏的细胞质蛋白信号转导和转录激活因子1 （Stat1）在Y701上磷酸化，二聚体并在细胞核中积累以激活ifn - γ应答基因的转录。为了最大限度地激活基因，Stat1转录激活域中的S727也可被ifn - γ诱导磷酸化。我们之前纯化了一组与Stat1转录激活域特异性相互作用的核蛋白。在本报告中，我们确定了其中一个多功能Ca2+/钙调素依赖性激酶（CaMK） II。我们证明ifn - γ在细胞中调动Ca2+通量并激活CaMKII。CaMKII可以直接与Stat1相互作用，并在体外磷酸化S727上的Stat1。Ca2+通量或CaMKII的抑制导致S727磷酸化和Stat1依赖性基因激活的缺乏，表明CaMKII在体内磷酸化Stat1 S727。因此，Stat1需要两个不同的细胞信号事件，ifn - γ受体占用和Ca2+通量，才能通过磷酸化调节实现最大的转录激活。
In response to IFN-gamma, the latent cytoplasmic protein signal transducers and activators of transcription 1 (Stat1) becomes phosphorylated on Y701, dimerizes, and accumulates in the nucleus to activate transcription of IFN-gamma-responsive genes. For maximal gene activation, S727 in the transcription activation domain of Stat1 also is inducibly phosphorylated by IFN-gamma. We previously purified a group of nuclear proteins that interact specifically with the Stat1 transcription activation domain. In this report, we identified one of them as the multifunctional Ca2+/calmodulin-dependent kinase (CaMK) II. We demonstrate that IFN-gamma mobilizes a Ca2+ flux in cells and activates CaMKII. CaMKII can interact directly with Stat1 and phosphorylate Stat1 on S727 in vitro. Inhibition of Ca2+ flux or CaMKII results in a lack of S727 phosphorylation and Stat1-dependent gene activation, suggesting in vivo phosphorylation of Stat1 S727 by CaMKII. Thus two different cellular signaling events, IFN-gamma receptor occupation and Ca2+ flux, are required for Stat1 to achieve maximal transcriptional activation through regulation of phosphorylation.