Sleckman Barry P, Chen Bo-Ruei
Birmingham, AL.
Trans Am Clin Climatol Assoc. 2025;135:281-293.
Genome instability is a hallmark of cancer, allowing for clonal evolution and improved tumor fitness. The mis-repair of DNA double-strand breaks (DSBs) is a major source of genome instability. DNA DSBs are normally repaired by homologous recombination (HR) and nonhomologous end joining (NHEJ). The nucleolytic resection of broken DNA ends generates single-stranded DNA (ssDNA) overhangs that are required for HR, but inhibitory to NHEJ. DNA end resection must be prevented in nondividing cells where NHEJ is the only active DSB repair pathway. Using a novel whole genome gRNA CRISPR/Cas9 screen, we identified the GID complex as functioning to protect DNA ends from nucleolytic resection. The GID complex contains multiple E3 ubiquitin ligase subunits and regulates the expression and function of pro-resection machinery. Thus, by antagonizing DNA end resection GID may prevent homology-mediated joining leading to aberrant DSB repair and genome instability in normal and cancerous nondividing cells.
基因组不稳定是癌症的一个标志，它允许克隆进化并提高肿瘤适应性。DNA双链断裂（DSB）的错误修复是基因组不稳定的主要来源。DNA DSB通常通过同源重组（HR）和非同源末端连接（NHEJ）进行修复。断裂DNA末端的核酸酶切除产生单链DNA（ssDNA）悬端，这是HR所必需的，但对NHEJ有抑制作用。在非分裂细胞中，NHEJ是唯一活跃的DSB修复途径，必须防止DNA末端切除。通过一项新颖的全基因组gRNA CRISPR/Cas9筛选，我们确定GID复合物的功能是保护DNA末端免被核酸酶切除。GID复合物包含多个E3泛素连接酶亚基，并调节促切除机制的表达和功能。因此，通过拮抗DNA末端切除，GID可能会阻止同源性介导的连接，从而导致正常和癌性非分裂细胞中异常的DSB修复和基因组不稳定。
