Lim Hoe Eun, Lim Hee Jung, Yoo Hae Yong
Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 06351, Republic of Korea.
Research Institute for Future Medicine, Samsung Medical Center, Seoul 06351, Republic of Korea.
Int J Mol Sci. 2024 Dec 5;25(23):13097. doi: 10.3390/ijms252313097.
Various DNA damage checkpoint control mechanisms in eukaryotic cells help maintain genomic integrity. Among these, NBS1, a key component of the MRE11-RAD50-NBS1 (MRN) complex, is an essential protein involved in the DNA damage response (DDR). In this study, we discovered that DNA damage-binding protein 1 (DDB1) interacts with NBS1. DDB1 is a DDR sensor protein found in UV-induced DNA replication blocks. Through pull-down and immunoprecipitation assays conducted in Xenopus egg extracts and human cell lines, we demonstrated a specific interaction between NBS1 and DDB1. DDB1 was also found to associate with several proteins that interact with NBS1, including DNA topoisomerase 2-binding protein 1 (TopBP1) and Mediator of DNA damage checkpoint protein 1 (MDC1). Notably, the interaction between DDB1 and NBS1 is disrupted in MDC1-depleted egg extracts, indicating that MDC1 is necessary for this interaction. Furthermore, the depletion of DDB1 leads to increased Chk1 activation upon DNA damage. These novel findings regarding the interaction between NBS1 and DDB1 provide new insights into how DDB1 regulates DNA damage pathways.
真核细胞中的各种DNA损伤检查点控制机制有助于维持基因组完整性。其中，NBS1是MRE11-RAD50-NBS1（MRN）复合物的关键组成部分，是参与DNA损伤反应（DDR）的必需蛋白质。在本研究中，我们发现DNA损伤结合蛋白1（DDB1）与NBS1相互作用。DDB1是一种在紫外线诱导的DNA复制阻滞中发现的DDR传感蛋白。通过在非洲爪蟾卵提取物和人类细胞系中进行的下拉和免疫沉淀试验，我们证明了NBS1与DDB1之间存在特异性相互作用。还发现DDB1与几种与NBS1相互作用的蛋白质相关联，包括DNA拓扑异构酶2结合蛋白1（TopBP1）和DNA损伤检查点蛋白1介导因子（MDC1）。值得注意的是，在耗尽MDC1的卵提取物中，DDB1与NBS1之间的相互作用被破坏，这表明MDC1对于这种相互作用是必需的。此外，DDB1的耗尽导致DNA损伤时Chk1激活增加。这些关于NBS1与DDB1相互作用的新发现为DDB1如何调节DNA损伤途径提供了新的见解。
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