Dissection of non-canonical DNA damage response mechanisms controlling the senescence program

解析控制衰老程序的非典型 DNA 损伤反应机制

• 批准号: RGPIN-2022-04385
• 负责人: Rodier, Francis
• 金额: $ 2.48万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=764444
• 关键词: Dissection; non; canonical; DNA; damage

Cellular senescence is a natural cell aging mechanism occurring in response to unrepaired genomic DNA damage caused by conditions like dysfunctional telomeres or chronic oxidative stress. Senescent cells are characterized by a senescence¬-associated stable proliferation arrest (SAPA) and by a secretory phenotype (SASP) that contribute to tissue remodeling during normal tissue repair or development. We and others have shown that the senescence program is controlled by the DNA damage response (DDR), which is an interlaced network of signalling pathways activated by DNA double-strand breaks (DSB). It remains unclear why and how the DDR, which is activated within minutes of a DSB (canonical response), establishes proliferation arrest rapidly via cell cycle checkpoints, but takes day to establish the stable SAPA and SASP. To understand the transition between the early canonical DDR and a potentially persistent DDR we developed longitudinal models of DNA damage-¬induced senescence via irradiation or controlled telomere uncapping in normal human cells. We discovered that telomere dysfunction triggers a rapid focal DDR activity accompanied by a transient cell cycle arrest, which is rapidly bypassed via DNA damage tolerance. Replicated dysfunctional telomeres then result in homologous recombination¬-mediated telomeric sister chromatid fusions underlying next mitosis genome instability. We also showed that a noncanonical DDR occurs several days following DNA damage induction and is characterized by a progressive accumulation of DDR components like ATM and the MRN complex on the chromatin. Our hypothesis is that the SAPA and the SASP require delayed alternative DDR activities when compared to the immediate canonical DDR involved in DNA repair and transient cell cycle arrest, a phenomenon we term non¬canonical DDR. The long-term objective of this research program is to characterize and define non¬canonical DDR signaling via the identification of the molecular regulators involved in this process and the evaluation of their impact on SAPA or SASP. Our specific short-term objectives are to characterize this novel non¬canonical DDR using a mix of targeted and unbiased strategies. We will identify the interactome and molecular regulators of non-canonical DDR signaling at the protein and chromatin/transcriptional level to understand the role of this network in establishing and maintaining senescence. Understanding the role and activities of the DDR remain one of the major current challenge in fundamental genome stability cell biology, the proposed research program will further describe a novel non¬canonical DDR network interlaced within genome stability and the establishment of cell senescence. This program will attract HQP to this cutting-edge research subject in a way that promote EDI and will train them with a variety of multidisciplinary skills.

细胞衰老是一种自然的细胞衰老机制，发生在响应未修复的基因组DNA损伤引起的条件，如功能失调的端粒或慢性氧化应激。衰老细胞的特征在于衰老相关的稳定增殖停滞（SAPA）和分泌表型（SASP），其有助于正常组织修复或发育期间的组织重塑。我们和其他人已经表明，衰老程序是由DNA损伤反应（DDR）控制的，DDR是由DNA双链断裂（DSB）激活的信号通路的交织网络。目前尚不清楚DDR为什么以及如何在DSB（典型反应）的几分钟内激活，通过细胞周期检查点快速建立增殖抑制，但需要一天时间才能建立稳定的SAPA和SASP。为了理解早期典型DDR和潜在持久性DDR之间的过渡，我们开发了正常人细胞中通过辐射或受控端粒脱帽的DNA损伤诱导衰老的纵向模型。我们发现，端粒功能障碍触发快速局灶性DDR活动，伴随着短暂的细胞周期停滞，这是通过DNA损伤耐受迅速绕过。然后，复制的功能失调的端粒导致同源重组介导的端粒姐妹染色单体融合，这是下一次有丝分裂基因组不稳定性的基础。我们还表明，非典型的DDR在DNA损伤诱导后几天发生，其特征是染色质上ATM和MRN复合物等DDR成分的逐渐积累。我们的假设是，当与涉及DNA修复和瞬时细胞周期停滞的直接规范DDR相比时，SAPA和SASP需要延迟的替代性DDR活性，我们将这种现象称为非规范DDR。该研究计划的长期目标是通过鉴定参与该过程的分子调节剂并评估其对SAPA或SASP的影响来表征和定义非经典DDR信号传导。我们具体的短期目标是使用有针对性的和无偏见的策略的组合来表征这种新颖的非规范DDR。我们将在蛋白质和染色质/转录水平上识别非经典DDR信号的相互作用组和分子调节因子，以了解该网络在建立和维持衰老中的作用。理解DDR的作用和活性仍然是基础基因组稳定性细胞生物学中当前的主要挑战之一，所提出的研究计划将进一步描述在基因组稳定性和细胞衰老的建立内交织的新型非规范DDR网络。该计划将吸引HQP到这个尖端的研究课题，以促进EDI的方式，并将培训他们与各种多学科的技能。