Mediator subunit MED25 links the jasmonate receptor to transcriptionally active chromatin
Mediator subunit MED25 links the jasmonate receptor to transcriptionally active chromatin
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介导亚基 MED25 将茉莉酸受体与转录活性染色质连接起来
DOI：
10.1073/pnas.1710885114
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发表时间：
2017-10-17
影响因子：
11.1
通讯作者：
Li, Chuanyou
中科院分区：
文献类型：
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作者：
An, Chunpeng;Li, Lin;Li, Chuanyou
F-box蛋白CORONATINE INSENSITIVE 1（COI 1）对植物激素茉莉酸（JA）的感应触发了由主调节因子MYC 2调节的深刻的转录变化。然而，目前还不清楚COI 1如何与一般的转录机制和染色质通信。在这里，我们表明，MED 25，介体辅激活因子复合物的一个亚基，物理和功能上与MYC 2靶启动子上的COI 1相互作用。MED 25还与组蛋白乙酰转移酶1（HAC 1）发生物理和功能性相互作用，后者选择性调节MYC 2靶点的组蛋白（H）3赖氨酸（K）9乙酰化。因此，MED 25整合了聚集在MYC 2靶点启动子上的调节信号。我们的研究结果揭示了一个基本的机制，调解人协调行动的遗传和表观遗传调节成一个协调一致的转录程序。茉莉酰-异亮氨酸（JA-Ile）是植物激素茉莉酸（JA）的活性形式，由功能性Skp-Cullin-F-box E3泛素连接酶复合物的组分F-box蛋白CORONATINE INSENSITIVE 1（COI 1）感知。COI 1对JA-Ile的感知迅速触发了基因组范围内的转录变化，这些变化在很大程度上受到碱性螺旋-环-螺旋转录因子MYC 2的调节。然而，目前仍不清楚JA-Ile受体蛋白COI 1是如何将转录特异性调节信号传递给RNA聚合酶II的一般转录机制的。在这里，我们报告说，植物转录辅激活因子复合物介导剂直接连接COI 1的启动子MYC 2的靶基因。MED 25是介体复合物的一个亚基，将COI 1带到MYC 2靶启动子，并促进COI 1依赖的茉莉酸-ZIM结构域（JAZ）转录抑制因子的降解。MED 25和COI 1影响彼此对MYC 2靶启动子的富集。此外，MED 25与组蛋白乙酰转移酶1（HAC 1）在物理和功能上相互作用，后者通过选择性调节MYC 2靶启动子的组蛋白（H）3赖氨酸（K）9（H3 K9）乙酰化在JA信号传导中发挥重要作用。此外，HAC 1在MYC 2靶启动子上的富集和功能依赖于COI 1和MED 25。因此，Mediator的MED 25界面将COI 1与HAC 1依赖性H3 K9乙酰化连接，以激活MYC 2调节的JA应答基因的转录。这项研究阐明了一个单一的中介子亚基如何将遗传和表观遗传调节因子的作用整合到一个协调一致的转录程序中。
Significance Sensing of the plant hormone jasmonate (JA) by the F-box protein CORONATINE INSENSITIVE 1 (COI1) triggers profound transcriptional changes that are regulated by the master regulator MYC2. However, it remains unclear how COI1 communicates with the general transcription machinery and chromatin. Here, we show that MED25, a subunit of the Mediator coactivator complex, physically and functionally interacts with COI1 on the promoters of MYC2 targets. MED25 also physically and functionally interacts with HISTONE ACETYLTRANSFERASE1 (HAC1), which selectively regulates histone (H) 3 lysine (K) 9 acetylation of MYC2 targets. Therefore, MED25 integrates regulatory signals that converge on the promoters of MYC2 targets. Our results reveal a fundamental mechanism by which Mediator coordinates the actions of both genetic and epigenetic regulators into a concerted transcriptional program. Jasmonoyl-isoleucine (JA-Ile), the active form of the plant hormone jasmonate (JA), is sensed by the F-box protein CORONATINE INSENSITIVE 1 (COI1), a component of a functional Skp–Cullin–F-box E3 ubiquitin ligase complex. Sensing of JA-Ile by COI1 rapidly triggers genome-wide transcriptional changes that are largely regulated by the basic helix–loop–helix transcription factor MYC2. However, it remains unclear how the JA-Ile receptor protein COI1 relays hormone-specific regulatory signals to the RNA polymerase II general transcriptional machinery. Here, we report that the plant transcriptional coactivator complex Mediator directly links COI1 to the promoters of MYC2 target genes. MED25, a subunit of the Mediator complex, brings COI1 to MYC2 target promoters and facilitates COI1-dependent degradation of jasmonate–ZIM domain (JAZ) transcriptional repressors. MED25 and COI1 influence each other’s enrichment on MYC2 target promoters. Furthermore, MED25 physically and functionally interacts with HISTONE ACETYLTRANSFERASE1 (HAC1), which plays an important role in JA signaling by selectively regulating histone (H) 3 lysine (K) 9 (H3K9) acetylation of MYC2 target promoters. Moreover, the enrichment and function of HAC1 on MYC2 target promoters depend on COI1 and MED25. Therefore, the MED25 interface of Mediator links COI1 with HAC1-dependent H3K9 acetylation to activate MYC2-regulated transcription of JA-responsive genes. This study exemplifies how a single Mediator subunit integrates the actions of both genetic and epigenetic regulators into a concerted transcriptional program.