Understanding the impact of DNA ADP-ribosylation on telomere function in cancer cells

研究总结/摘要 癌细胞必须使用端粒延长机制，以确保复制不朽。15%的癌症 细胞利用端粒交替延长(ALT)，这是一种同源重组介导的途径。 ALT机制的扰动可以通过破坏参与ADP-核糖化的酶来实现，a 翻译后修饰，调节几个细胞过程，包括转录、代谢和 DNA修复。参与ADP-核糖化的酶的药理抑制已被证明是 癌症治疗中巨大的生物医学价值。在过去的30年里，研究主要建立在密集的基础上 研究ADP-核糖化作为一种修饰，仅在蛋白质上发现。然而，新的证据是 核酸，DNA和RNA，是ADP的直接来源，甚至是主要来源- 核糖化，尤其是在DNA损伤之后。这一范式转变对我们的 了解腺苷二磷酸核糖化在ALT中的生理作用。因此，提高我们对 这种新的DNA修饰的细胞靶点和机制将对增强的 ADP-核糖靶向治疗，为ALT癌症患者取得更好的临床结果。 我发现端粒，染色体末端的特殊结构，是主要的 多聚ADP核糖聚合酶(PARP1)，多ADP核糖水解酶(PARG)， 和一种新发现的被称为末端ADP-核糖水解酶(TARG1)的因子。我发现了PARP1 协调端粒DNA序列的ADP-核糖化和TARG1，与 PARG负责从端粒DNA中去除ADP-核糖。此外，我证明了这种扰乱 TARG1的表达引发ALT端粒的复制并发症，可能具有灾难性的 对癌细胞活性的影响。在目标1中，我将进一步评估DNA ADP-核糖化和 调节其去除的因素对端粒功能和ALT的影响存在缺陷。在目标2中，我将剖析 调节DNA ADP核糖化的TARG1和PARG对癌细胞活力的共同抑制，以及 端粒功能障碍在其中的作用。这项研究将为这部小说提供新的关键知识 ADP核糖化在ALT中的基础作用。通过探索其放松管制对ALT的影响，这 这项研究将有助于对ADP-核糖化的解除管制如何有助于癌症治疗的新见解。

RESEARCH SUMMARY/ABSTRACT Cancer cells must employ a telomere lengthening mechanism to ensure replicative immortality. 15% of cancer cells utilize Alternative Lengthening of Telomeres (ALT), a homologous recombination-mediated pathway. Perturbation of the ALT mechanism can be achieved by disruption of enzymes involved in ADP-ribosylation, a post-translational modification that regulates several cellular processes including transcription, metabolism, and DNA repair. The pharmacological inhibition of enzymes involved in ADP-ribosylation has proven to be of immense biomedical value in cancer therapy. Over the last 30 years, studies have primarily built on intensive investigation of ADP-ribosylation as a modification that is exclusively found on proteins. Yet, new evidence is emerging that nucleic acids, DNA and RNA, are direct and perhaps even the predominant sources of ADP- ribosylation, especially in the aftermath of DNA damage. This paradigm shift has major implications for our understanding of the physiological function of ADP-ribosylation in ALT. Thus, improving our knowledge of the cellular targets and mechanisms of this new DNA modification will be vital for the development of enhanced ADP-ribose-targeting therapeutics that achieve better clinical outcomes for ALT cancer patients. I found that telomeres, specialized structures at the ends of the chromosomes, are targets of the major ADP-ribosylation enzymes; Poly ADP-ribose Polymerase (PARP1), Poly ADP-ribose Glycohydrolase (PARG), and a newly identified factor known as Terminal ADP-ribose Hydrolase (TARG1). I uncovered that PARP1 coordinates the ADP-ribosylation of telomeric DNA sequences and that TARG1, acting in conjunction with PARG, is responsible for the removal ADP-ribose from telomeric DNA. Furthermore, I show that the disruption of TARG1 expression provokes replicative complications at ALT telomeres that may have catastrophic consequences for cancer cell viability. In Aim 1, I will further assess the impact of DNA ADP-ribosylation and defects in factors that regulate its removal on telomere function and ALT. In Aim 2, I will dissect the impact of co-suppression of TARG1 and PARG, factors that regulate DNA ADP-ribosylation, on cancer cell viability, and the contribution of telomere dysfunction therein. This study will provide new and crucial knowledge on the novel and fundamental role of ADP-ribosylation in ALT. By exploring the impact that its deregulation has on ALT, this study will contribute new insights into how the deregulation of ADP-ribosylation contributes to cancer treatment.