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(申请人提供)：这项研究旨在了解斯巴达在跨病变合成(TLS)和紫外线诱导致癌中的作用。TLS是一种复制后修复途径，在DNA复制过程中，它介导绕过阻碍复制分叉的巨大DNA损伤。DNA损伤的旁路是由专门的低保真TLS聚合酶介导的，它可以有效地复制扭曲或庞大的DNA加合物，将损伤留在稍后的时间点修复。TLS的关键步骤是复制聚合酶与TLS聚合酶的切换，这被认为是由依赖于RAD18的增殖细胞核抗原泛素化(UB-PCNA)介导的。然而，确切的机制尚不清楚。我们确定斯巴达人是TLS的关键监管者。Spartan的耗尽使细胞对紫外线损伤敏感，导致增殖细胞核抗原的单一泛素化减少，同时伴随着RAD18染色质结合和RAD18对DNA损伤位置的定位减少。有趣的是，斯巴达在正常情况下与复制的DNA聚合酶结合，但在紫外线损伤时优先与TLS聚合酶POLH结合。根据我们的观察，我们认为斯巴达是TLS的关键调节因子，需要稳定DNA损伤部位的RAD18和UB-PCNA，并可能直接调节TLS过程中从复制聚合酶到TLS聚合酶的转换。然而，斯巴达如何在TLS过程中调节其调节功能以及DNA聚合酶之间的切换尚不清楚，这将是本研究的重点。本建议的具体目的是：1)确定斯巴达在紫外线损伤时TLS中的作用；2)确定斯巴达介导的TLS在紫外线诱导的致癌和化疗药物耐药中的作用；3)确定斯巴达在体内的生理功能。这项拟议的研究不仅将为TLS过程的调控机制提供有用的见解，还将探索以斯巴达为靶点用于癌症治疗的潜力。