Mechanisms of p300 Activation During Pluripotency and Differentiation.

多能性和分化过程中 p300 激活的机制。

• 批准号: 10685500
• 负责人: Laura Banaszynski
• 金额: $ 42.04万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-17 至 2027-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10685500
• 关键词: Acetate-CoA Ligase; Acetyl Coenzyme A; Acetylation; Acetyltransferase; Amaze; Binding; Binding Proteins; Biological; Biological Assay; Biological Process; Biology; Cell physiology; Cells; Chemicals; Chromatin; Defect; Deposition; Development; Disease; EP300 gene; Embryo; Enhancers; Event; Failure; Family; Gene Expression; Genes; Genetic Enhancer Element; Genetic Models; Genetic Transcription; Genomics; Goals; Histone H3; Histone H3.3; Histones; Infertility; Knock-in; Knowledge; Link; Lysine; Malignant Neoplasms; Mediating; Modeling; Molecular; Mus; Nuclear; Pathogenesis; Pathologic; Phosphorylation; Play; Pre-implantation Embryo Development; Process; Proteins; Proteomics; Regenerative Medicine; Regulatory Element; Role; Specific qualifier value; Syndrome; Testing; Time; Transcription Coactivator; Transcriptional Activation; Variant; Work; cell fate specification; cell type; early pregnancy loss; embryonic stem cell; epigenetic regulation; experimental study; human disease; human model; improved; in vivo; inhibitor; insight; mouse model; novel; p300/CBP-Associated Factor; pluripotency; protein protein interaction; recruit; scaffold; tool; transcription factor

SUMMARY Pluripotency is a critical model for understanding fundamental principles of cell fate specification. This process makes selective use of enhancers, regulatory elements that facilitate the transcription of cell-type specific genes. Although changes in enhancer activity are predicted to have broad developmental and pathological implications, we currently have limited understanding of how enhancers regulate development and disease, in part due to our incomplete understanding of the mechanisms by which enhancers regulate gene expression. Increased understanding of the molecular events that regulate enhancer activity, particularly under developmental contexts, will provide important insights into congenital diseases that occur with their dysregulation. The chromatin state at enhancers is characterized by the presence of the histone variant, H3.3, and recruitment of the CBP/p300 family of transcriptional coactivators. Our recent studies demonstrate that H3.3 deposition at enhancers allows for variant-specific phosphorylation that stimulates p300 acetyltransferase activity towards its substrate histone H3 lysine 27 (H3K27ac) in mouse embryonic stem cells (ESCs). Further, we find that CBP and p300 carry out distinct functions in ESCs, with p300 playing a greater role in maintaining H3K27ac in ESCs. Finally, we find that reduced H3K27ac due to H3.3 or p300 deletion is well tolerated in ESCs, with little correlated change in transcription. However, both H3.3 and p300 are required for differentiation, suggesting that H3.3 deposition and subsequent high levels of H3K27ac may be more important for activating gene transcription than for maintaining ongoing transcription in ESCs. The objective of this proposal is to dissect the molecular and functional mechanisms by which enhancers are activated both in pluripotency and differentiation. In the first aim, we will determine how H3.3 phosphorylation stimulates p300 activity in ESCs. In the second aim, we will determine why H3K27 acetyltransferase activity is restricted to p300 in ESCs. Finally, in the third aim, we will use the tools of chemical biology and novel mouse models that we have generated to ask how H3.3 and p300 function to promote transcription during pre-implantation development. Collectively, our work will explore molecular links between H3.3 and p300 in enhancer activation during the time at which the first lineage specification events occur, with important implications for understanding how enhancer dysregulation contributes to human disease.

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