Roles of Spartan in translesion synthesis and UV-induced carcinogenesis

Spartan 在跨损伤合成和紫外线诱发的致癌作用中的作用

• 批准号: 9319644
• 负责人: GARGI GHOSAL
• 金额: $ 13.39万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9319644
• 关键词: Binding; Biological Assay; Biological Process; Butane; Bypass; CRISPR/Cas technology; Cell Proliferation; Cell Survival; Cells; Chromatin; Cutaneous Melanoma; DNA; DNA Adducts; DNA Damage; DNA Repair Pathway; DNA biosynthesis; DNA lesion; DNA replication fork; DNA-Directed DNA Polymerase; Databases; Development; Epithelium; Fiber; Genes; Genomic Instability; In Vitro; Knock-out; Knockout Mice; Lead; Left; Lesion; Malignant Neoplasms; Mediating; Melanoma Cell; Metalloproteases; Metastatic Melanoma; Modeling; Monoubiquitination; Mus; Mutagenesis; Mutation; Pathway interactions; Peptide Hydrolases; Pharmaceutical Preparations; Physiological; Play; Polymerase; Process; Proteins; Proteolysis; Pyrimidine Dimers; Resistance; Role; Site; Skin; Skin Cancer; Skin Carcinogenesis; Sun Exposure; System; The Cancer Genome Atlas; Time; UV carcinogenesis; UV induced; UV induced DNA damage; Ubiquitination; Ultraviolet Rays; Ultraviolet Therapy; base; cancer cell; cancer therapy; chemotherapeutic agent; in vivo; insight; melanocyte; melanoma; mutant; neoplastic cell; overexpression; prevent; public health relevance; reconstitution; repaired; response; targeted cancer therapy; tumorigenesis; ultraviolet damage

 DESCRIPTION (provided by applicant): This study aims at understanding the roles of Spartan in translesion synthesis (TLS) and UV-induced carcinogenesis. TLS is a post-replication repair pathway, which mediates bypass of bulky DNA lesions that stall replication forks, during DNA replication. Bypass of DNA lesions is mediated by specialized low-fidelity TLS polymerase that can replicate over distortions or bulky DNA adducts efficiently, leaving behind the lesion to be repaired at a later time point. The critical step in TLS is the switch of the replicative polymeras with TLS polymerase, which is proposed to be mediated by RAD18-dependent ubiquitination of PCNA (ub-PCNA). However, the exact mechanism is not clear. We identified Spartan as a key regulator of TLS. Depletion of Spartan renders cells sensitive to UV damage, results in a decrease in PCNA mono-ubiquitination, which is accompanied by a reduction of RAD18 chromatin association and RAD18 localization to DNA damage sites. Interestingly, Spartan binds to replicative DNA polymerase under normal conditions, but preferentially associates with TLS polymerase POLH upon UV damage. Based on our observations, we proposed that Spartan is a key regulator of TLS, required to stabilize RAD18 and ub-PCNA at the sites of DNA damage and may directly regulate the switch from replicative polymerase to TLS polymerase during TLS. However, how Spartan mediates its regulatory functions and the switch between the DNA polymerases during TLS is not known and will be the focus of this study. The specific aims for this proposal are: Aim 1) Determine the function of Spartan in TLS upon UV damage; Aim 2) Determine the roles of Spartan mediated TLS in UV-induced carcinogenesis and resistance to chemotherapeutic agents; Aim 3) Determine the in vivo physiological functions of Spartan. This proposed study will not only provide useful insights into the regulatory mechanism of TLS process, but also, will explore the potential of targeting Spartan for cancer therapy.

 描述（由适用提供）：本研究旨在了解斯巴达人在跨跨综合（TLS）和紫外线诱导的致癌作用中的作用。 TLS是一种复制后修复途径，在DNA复制过程中介导了停滞叉子的大量DNA病变的旁路。 DNA病变的旁路是由专业的低保真TLS聚合酶介导的，该聚合酶可以有效地复制扭曲或笨重的DNA加合物，从而在以后的时间点上修复病变。 TLS中的关键步骤是复制性聚合物与TLS聚合酶的转换，该聚合酶被认为是由PCNA（UB-PCNA）的Rad18依赖性泛素化介导的。但是，确切的机制尚不清楚。我们将斯巴达人确定为TLS的关键调节剂。斯巴达人的耗竭使细胞对紫外线损伤敏感，从而导致PCNA单泛素化降低，这是通过降低Rad18染色质缔合和RAD18定位到DNA损伤位点来完成的。有趣的是，斯巴达坦在正常条件下结合以复制DNA聚合酶，但优先将与TLS聚合酶Polh相关联合紫外线损伤。根据我们的观察结果，我们提出Spartan是在DNA损伤部位稳定RAD18和UB-PCNA所需的关键调节剂，并且可能在TLS期间直接调节从复制性聚合酶到TLS聚合酶的开关。但是，斯巴达坦如何介导其调节功能以及在TLS期间的DNA聚合酶之间的切换是不知道的，这将是本研究的重点。该提案的具体目的是：目标1）确定紫外线损坏时斯巴达人在TLS中的功能；目标2）确定斯巴达式介导的TLS在紫外线诱导的癌变和对化学治疗剂的抗性中的作用；目标3）确定斯巴达坦的体内生理功能。这项拟议的研究不仅将提供有关TLS过程调节机制的有用见解，而且还将探索将斯巴达靶向癌症治疗的潜力。