Ras-Raf-MAPK signaling promotes nuclear localization of FOXA transcription factor SGF1 via Ser91 phosphorylation
Ras-Raf-MAPK signaling promotes nuclear localization of FOXA transcription factor SGF1 via Ser91 phosphorylation
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Ras-Raf-MAPK 信号通过 Ser91 磷酸化促进 FOXA 转录因子 SGF1 的核定位
DOI：
10.1016/j.bbamcr.2018.01.007
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发表时间：
2018-04-01
影响因子：
5.1
通讯作者：
Li, Sheng
中科院分区：
文献类型：
--
作者：
Ma, Li;Li, Kang;Li, Sheng
Ras-Raf-MAPK信号转导促进细胞增殖和细胞存活。我们以前报道，Ras 1（CA）的过表达，特别是在后部丝腺（PSG）的家蚕，增加丝素蛋白的合成和细胞的大小，从而提高丝绸产量。在这项研究中，我们比较了野生型和Ras 1（CA）过表达家蚕PSG的iTRAQ磷酸化蛋白质组学谱。丝腺因子1（SGF 1）是一种FOXA转录因子，在激活丝素蛋白基因表达中起关键作用，被鉴定为含有Ser 91作为潜在MAPK磷酸化位点的磷蛋白。SGF 1的Ser 91磷酸化通过Ras 1（CA）过表达增强，并且这一发现通过选择反应监测得到验证。因此，在家蚕发育过程中，MAPK活性与SGF 1的Ser 91磷酸化及其在PSG细胞中的核定位密切相关。Ras 1（CA）过表达和Ras信号抑制剂处理分别促进或抑制了SGF 1的核定位; Ser 91突变为Ala 91消除了SGF 1的核定位。此外，MAPK与SGF 1结合并直接磷酸化Ser 91，证明Ser 91是SGF 1中的MAPK磷酸化位点。总之，Ras-Raf-MAPK信号转导促进了SGF 1核定位，通过Ser 91磷酸化在蚕中进行反式激活，表明FOXA转录因子在动物中通过MAPK磷酸化进行调节。
Ras-Raf-MAPK signaling promotes cell proliferation and cell survival. We previously reported that Ras1(CA) overexpression, specifically in the posterior silk glands (PSGs) of the silkworm Bombyx mori, increased fibroin synthesis and cell size, resulting in improved silk yields. In this study, we compared the iTRAQ-based phosphoproteomic profiles of PSGs from wild-type and Ras1(CA)-overexpressing silkworms. Silk gland factor 1 (SGF1), a FOXA transcription factor that plays a critical role in activating fibroin gene expression, was identified as a phosphoprotein harboring Ser91 as a potential MAPK phosphorylation site. Ser91 phosphorylation of SGF1 was enhanced by Ras1(CA) overexpression, and this finding was verified by selected reaction monitoring. Consistently, MAPK activity is well correlated with Ser91 phosphorylation of SGF1 and its nuclear localization in PSG cells during silkworm development. Ras1(CA) overexpression and treatment with inhibitors of Ras signaling promoted or inhibited SGF1 nuclear localization, respectively; mutation of Ser91 to Ala91 eliminated SGF1 nuclear localization. Moreover, MAPK binds to SGF1 and directly phosphorylates Ser91, demonstrating Ser91 as a MAPK phosphorylation site in SGF1. In conclusion, Ras-Raf-MAPK signaling promotes SGF1 nuclear localization for transactivation via Ser91 phosphorylation in silkworms, showing that FOXA transcription factors are regulated via MAPK phosphorylation in animals.