Regulation of the histone acetyltransferase p300 by TRIM25

TRIM25 对组蛋白乙酰转移酶 p300 的调节

• 批准号: 317781219
• 负责人: Privatdozentin Dr. Christine Blattner
• 金额: --
• 依托单位: Institut für Biologische und Chemische Systeme (IBCS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/317781219?language=en
• 关键词: Regulation; histone; acetyltransferase; p300; TRIM25

Due to its acetyltransferase-activity, its E3 ligase activity and by acting as a scaffold for protein-protein interactions, p300 is essential for a multitude of cellular processes and its misregulation is involved in several diseases. Yet, despite its importance, our knowledge about its regulation is still very limited. While we were investigating the regulation of p53 by TRIM25 (Zhang et al., 2015), we observed that in the presence of TRIM25 p300 abundance and p300-dependent p53 activity were strongly decreased. TRIM25 is a member of the TRIM-protein family, a protein family that is characterized by the presence of a tripartite motif at the N-terminus of TRIM proteins consisting of a RING-domain, one or two B-boxes and a coiled-coil region. Despite having a RING-domain and E3 ligase activity e.g. towards 14-3-3 sigma, TRIM25 was unable to target p300 for degradation by 26S proteasomes. Instead, we could inhibit p300 degradation by inhibitors of lysosomes. How TRIM25 targets p300 to lysosomal degradation is not known. We hypothesize that TRIM25 somehow mediates that p300 aggregates in cellular aggresomes that are then fitted into the autophagy pathway. In this context, TRIM25 could participate in the aggregation of p300 in aggresomes or in the delivery of p300 to autophagosomes. By using inhibitors of various degradation pathways and dominant negative mutants, by downregulating proteins that may be involved in p300 degradation with RNAi, by investigating whether and which post-translational modifications are involved, by investigating protein-protein-interactions and by microscopic studies, we will challenge our hypothesis and determine whether (i) p300 is degraded by the authophagy pathway (ii) whether degradation of p300 involves the formation of aggresomes and (iii) how TRTIM25 mediates the degradation of p300. Since p300 is a central node of transcriptional control, we further hypothesize that via the regulation of p300, TRIM25 has an as yet undervalued impact on gene transcription. We propose to investigate the transcriptome of cells and tissues with and without TRIM25 in a genome wide manner. Downregulation of p300 by RNAi in some of the cells will allow us to distinguish between p300-dependent and p300-independent processes. In summary, the proposed experiments will strongly increase our knowledge about the regulation of p300 and the activity of TRIM25, In addition, they may allow additional and novel insights into the function of TRIM proteins as autophagy-re/adaptors, a function that only recently has been elucidated.

由于其乙酰转移酶活性，其E3连接酶活性和作为蛋白质-蛋白质相互作用的支架，p300是许多细胞过程所必需的，并且其失调与多种疾病有关。然而，尽管其重要性，我们对其监管的了解仍然非常有限。当我们研究TRIM 25对p53的调节时（Zhang等人，2015），我们观察到在TRIM 25存在下，p300丰度和p300依赖性p53活性强烈降低。TRIM 25是TRIM蛋白家族的成员，该蛋白家族的特征在于在TRIM蛋白的N-末端存在由RING结构域、一个或两个B盒和卷曲螺旋区组成的三联基序。尽管具有RING结构域和E3连接酶活性，例如对14 - 3 - 3 σ的活性，但TRIM 25不能靶向p300以被26 S蛋白酶体降解。相反，我们可以通过溶酶体抑制剂抑制p300降解。TRIM25如何靶向p300以使其发生溶酶体降解尚不清楚。我们假设TRIM25以某种方式介导p300在细胞侵袭体中聚集，然后将其装配到自噬途径中。在这种情况下，TRIM25可以参与p300在侵袭体中的聚集或参与p300向自噬体的递送。通过使用各种降解途径的抑制剂和显性失活突变体，通过用RNAi下调可能参与p300降解的蛋白质，通过研究是否涉及翻译后修饰以及涉及哪些翻译后修饰，通过研究蛋白质-蛋白质相互作用以及通过显微镜研究，我们将挑战我们的假设并确定（i）p300是否通过自噬途径降解（ii）p300的降解是否涉及侵袭体的形成和（iii）TRTIM25如何介导p300的降解。由于p300是转录控制的中心节点，我们进一步假设，通过p300的调节，TRIM25对基因转录具有尚未被低估的影响。我们建议以全基因组的方式研究具有和不具有TRIM25的细胞和组织的转录组。在一些细胞中通过RNAi下调p300将使我们能够区分p300依赖性和p300非依赖性过程。总之，所提出的实验将大大增加我们对p300的调节和TRIM 25的活性的了解，此外，它们可能允许对TRIM蛋白作为自噬/适配器的功能的额外和新颖的见解，该功能最近才被阐明。