The role of RNF138 in DNA end resection is regulated by ubiquitylation and CDK phosphorylation.

Double-strand breaks (DSBs) are DNA lesions that pose a significant threat to genomic stability. The repair of DSBs by the homologous recombination (HR) pathway is preceded by DNA end resection, the 5' to 3' nucleolytic degradation of DNA away from the DSB. We and others previously identified a role for RNF138, a really interesting new gene finger E3 ubiquitin ligase, in stimulating DNA end resection and HR.

Quantification of protein enrichment at site-specific DNA double-strand breaks by chromatin immunoprecipitation in cultured human cells.

Here, we present a chromatin-immunoprecipitation-based protocol to quantify the recruitment of proteins adjacent to site-specific DNA double-strand breaks (DSBs), such as proteins involved in DSB repair. We describe steps to induce DSBs in U2OS osteosarcoma cells stably expressing the restriction endonucleases FokI or AsiSI. We then detail the procedures of chromatin isolation and immunoprecipitation, followed by protein elution and quantitative-PCR-based quantification of DNA.

BMI-1 regulates DNA end resection and homologous recombination repair.

BMI-1 is an essential regulator of transcriptional silencing during development. Recently, the role of BMI-1 in the DNA damage response has gained much attention, but the exact mechanism of how BMI-1 participates in the process is unclear. Here, we establish a role for BMI-1 in the repair of DNA double-strand breaks by homologous recombination (HR), where it promotes DNA end resection.

The Role of Polycomb Group Protein BMI1 in DNA Repair and Genomic Stability.

The polycomb group (PcG) proteins are a class of transcriptional repressors that mediate gene silencing through histone post-translational modifications. They are involved in the maintenance of stem cell self-renewal and proliferation, processes that are often dysregulated in cancer. Apart from their canonical functions in epigenetic gene silencing, several studies have uncovered a function for PcG proteins in DNA damage signaling and repair.

SUMOylation mediates CtIP's functions in DNA end resection and replication fork protection.

Double-strand breaks and stalled replication forks are a significant threat to genomic stability that can lead to chromosomal rearrangements or cell death. The protein CtIP promotes DNA end resection, an early step in homologous recombination repair, and has been found to protect perturbed forks from excessive nucleolytic degradation. However, it remains unknown how CtIP's function in fork protection is regulated.