组蛋白乙酰化介导的生长素信号转导调控顶端分生组织维持的分子机理

生长素通过其信号转导途径中的ARF家族转录因子调控下游基因转录。ARF家族分为转录激活因子和转录抑制因子两类。近年来的研究工作揭示了转录激活因子MP的作用机制，而以ARF3为代表的转录抑制因子调控下游基因转录的机理目前仍不清楚。研究表明MP参与了茎端分生组织维持，ARF10和ARF16调控根端分生组织维持，然而其他ARF家族成员，尤其是其中的转录抑制因子是否以及如何参与顶端分生组织维持调控尚不清楚。我们的前期工作发现，ARF3及其互作蛋白AIP1突变影响顶端分生组织活动；ARF3直接结合WUS和WOX5启动子并抑制它们转录；ARF3与组蛋白去乙酰化酶复合物的SAP18亚基互作；ARF3和AIP1突变造成WUS和WOX5启动子区域乙酰化水平升高。本申请拟在此基础上进一步研究ARF3—AIP1互作通过调节组蛋白乙酰化修饰调控顶端分生组织维持的机理，为ARF家族转录抑制因子作用机理提供新信息。

Auxin signaling mediates the transcription of down-stream genes by the activity of AUXIN RESPONSE FACTORs (ARFs). ARF family can be divided into two subgroups, including transcriptional activators and repressors. Recent studies revealed the mechanisms of transcriptional regulation mediated by MONOPTEROS (MP/ARF5), one of the transcriptional activators, but those of the repressors remain elusive. Previous studies have shown that MP is involved in the regulation of shoot apical meristem maintenance, while ARF10 and ARF16 regulate the maintenance of root apical meristem. However, whether other ARFs play roles in these processes and how do they exert their functions remain unknown. Our previous work indicates that mutations in ARF3 and its interacting protein ARF3 Interacting Protein 1(AIP1) affected the activity of apical meristems. ARF3 directly binds the promoters of WUS and WOX5 and represses their expression. ARF3 also interacts with SAP18, the subunit of histone deacetylase complex. Defects in ARF3 and AIP1 increased the levels of histione H3 acetylation in WUS and WOX5 promoter regions. Based on these results, we intend to further analyze the regulation of apical meristem maintenance by ARF3—AIP1 interaction, and investigate the molecular mechanisms underlying the transcriptional regulation of ARF3 via mediating histione H3 acetylation. The results will facilitate our understanding on the mechanisms of apical meristem maintenance, and the transcriptional regulation of ARF repressors.