Acetylation of KLF5 Alters the Assembly of p15 Transcription Factors in Transforming Growth Factor-β-mediated Induction in Epithelial Cells
Acetylation of KLF5 Alters the Assembly of p15 Transcription Factors in Transforming Growth Factor-β-mediated Induction in Epithelial Cells
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DOI：
10.1074/jbc.m109.007096
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发表时间：
2009-07-03
影响因子：
4.8
通讯作者：
Dong, Jin-Tang
中科院分区：
文献类型：
--
作者：
Guo, Peng;Zhao, Ke-Wen;Dong, Jin-Tang
KLF 5在包括增殖和分化在内的多种细胞过程中发挥重要作用。最近，KLF 5被证明可以逆转其在转化生长因子β（TGF β）介导的乙酰化后的增殖和p15调节中的功能。为了了解KLF 5乙酰化在TGF β诱导的p15转录中的作用，我们在TGF β的背景下表征了KLF 5与其他转录因子和启动子DNA元件的相互作用。KLF 5与Smad 2 -4和Miz-1以TGF β非依赖性方式相互作用，但仅在TGF β激活时与Myc相互作用，并且至少一些相互作用对TGF β诱导的p15转录具有累加效应。Oligo pulldown分析表明Myc与Inr元件的结合是KLF 5依赖性的，当KLF 5可用时，TGF β可以增强Myc与Inr元件的结合。此外，TGF β诱导KLF 5和p300乙酰化酶之间的相互作用，KLF 5的乙酰化是Smad 4与p300结合所必需的。KLF 5乙酰化失败不仅会阻止p300组装的Smad 4-KLF 5复合物在p15启动子上形成，而且还会影响Smad 4和FOXO 3在体内与p15启动子的结合。这些发现表明，在没有TGF β的情况下，一些KLF 5与细胞核中的Smads结合，而另一些KLF 5与p15启动子上的Miz-1结合以抑制其转录。TGF β的激活将p300募集到KLF 5-Smad复合物中以乙酰化KLF 5，并且具有乙酰化KLF 5的复合物结合到Smad结合元件并改变其他因子与p15启动子的结合以诱导其转录。
KLF5 plays important roles in a variety of cellular processes including proliferation and differentiation. Recently KLF5 was shown to reverse its function in proliferative and p15 regulation upon transforming growth factor-beta (TGF beta)-mediated acetylation. To understand how KLF5 acetylation functions in TGF beta-induced p15 transcription, we characterized the interactions of KLF5 with other transcription factors and promoter DNA elements in the context of TGF beta. KLF5 interacted with Smad2-4 and Miz-1 in a TGF beta-independent manner, but interacted with Myc only when TGF beta was activated, and at least some of the interactions had an additive effect on TGF beta-induced p15 transcription. Oligo pulldown assays showed that binding of Myc to the Inr element was KLF5-dependent, and TGF beta could enhance the binding when more KLF5 was available. Furthermore, TGF beta-induced an interaction between KLF5 and the p300 acetylase, and acetylation of KLF5 was necessary for Smad4 to associate with p300. Failure in KLF5 acetylation not only prevented p300-assembled Smad4-KLF5 complex formation on p15 promoter but also affected the binding of Smad4 and FOXO3 on the p15 promoter in vivo. These findings suggest that without TGF beta, some KLF5 associates with Smads in the nucleus and other KLF5 associates with Miz-1 on the p15 promoter to repress its transcription. Activation of TGF beta recruits p300 to the KLF5-Smad complex to acetylate KLF5, and the complex with acetylated KLF5 binds to the Smad binding element and alters the binding of other factors to p15 promoter to induce its transcription.