IκB kinase α-mediated derepression of SMRT potentiates acetylation of RelA/p65 by p300
IκB kinase α-mediated derepression of SMRT potentiates acetylation of RelA/p65 by p300
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DOI：
10.1128/mcb.26.2.457-471.2006
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发表时间：
2006-01-01
影响因子：
5.3
通讯作者：
Mayo, MW
中科院分区：
文献类型：
--
作者：
Hoberg, JE;Popko, AE;Mayo, MW
在过去的几年中，在鉴定染色质调控的nf - κ B转录事件方面取得了重大进展。利用层粘连蛋白附着或肿瘤坏死因子α作为NF-kappa B激活的生理刺激，我们证明了IKK α的I -kappa B激酶在不同的阶段被募集到染色质上。在初始阶段，IKK α负责从p50同型二聚体中去抑制维甲酸和甲状腺激素受体(SMRT)-组蛋白去乙酰化酶3 （HDAC3）协同抑制复合物的沉默介质。然而，在后期，染色质结合的IKK α协调RelA/p65（S536）和SMRT（S2410）的同时磷酸化，通过染色质免疫沉淀（ChIP）测定。尽管磷酸化的SMRT仍然与NF-kappa B的活性p50-ReIAp65异源二聚体结合，但染色质相关HDAC3活性的丧失证明了SMRT的抑制。ChIP和re-ChIP分析表明ReWp65（S536）和SMRT（S2410）的磷酸化发生在ReIA/p65在K310位点的乙酰化之前。此外，IKK α诱导的ReWp65（S536）磷酸化取代了辅抑制因子活性，允许p300介导的RelAp65乙酰化。引入ReIA/p65和SMRT蛋白的非磷酸化突变体或抑制IKK活性可通过拴住SMRT- hdac3复合物而主动抑制NF-kappa B启动子。与控制HDAC1与CBP/p300乙酰转移酶交换的RelA/p65的Rel同源域中的磷酸化类似，我们证明ReIA/p65（S536）的转激活域中的磷酸化取代了SMRT-HDAC3抑制因子的活性，使p300能够使RelA/p65乙酰化。
Over the last several years, significant progress has been made in identifying chromatin-regulated events that govern NF-kappa B transcription. Using either laminin attachment or tumor necrosis factor alpha as a physiological stimulus of NF-kappa B activation, we demonstrate that I kappa B kinase of (IKK alpha) is recruited to chromatin in distinct phases. In the initial phase, IKK alpha is responsible for derepressing the silencing mediator for retinoic acid and thyroid hormone receptor (SMRT)-histone deacetylase 3 (HDAC3) corepressor complex from the p50 homodimer. However, in the latter phase, chromatin-bound IKK alpha coordinates the simultaneous phosphorylation of RelA/p65(S536) and SMRT(S2410) as detected by chromatin immunoprecipitation (ChIP) assays. Although phosphorylated SMRT remains bound to the active p50-ReIAp65 heterodimer of NF-kappa B, derepression of SMRT is evidenced by the loss of chromatin-associated HDAC3 activity. ChIP and re-ChIP analysis demonstrates that phosphorylation of ReWp65(S536) and SMRT(S2410) occurs prior to acetylation of ReIA/p65 at K310. Moreover, IKK alpha-induced phosphorylation of ReWp65(S536) displaces corepressor activity, allowing p300-mediated acetylation of RelAp65. Introduction of nonphosphorylatable mutants of ReIA/p65 and SMRT proteins or the inhibition of IKK activity results in active repression of NF-kappa B promoters by tethering the SMRT-HDAC3 complex. Similar to phosphorylation within the Rel homology domain of RelA/p65, which governs an exchange of HDAC1 for CBP/p300 acetyltransferases, we demonstrate that phosphorylation within the transactivation domain of ReIA/p65(S536) displaces SMRT-HDAC3 repressor activity, allowing p300 to acetylate RelA/p65.