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Biomedical subjects

Giselle C Lee

Publications and source records attributed to Giselle C Lee.

3 recordsLinked to original sources

Targeting cancer-specific mutations with RNA-triggered chromatin shredding.

Genetic mutations that drive cancer often occur in tumour-suppressor proteins such as the p53 transcription factor, which is altered in 40-50% of cases1,2. However, current therapies often fail to target these mutations because the mutant proteins typically lack defined drug-binding pockets and restoring their endogenous function has proven challenging. Here we program Cas12a2, an RNA-guided CRISPR nuclease with trans-nucleolytic cleavage activity3,4, to kill cancer cells selectively by targeting cancer-specific transcripts. This approach limited cell growth by inducing trans shredding of chromatin and triggering DNA-damage responses and cell death. In contrast to existing methods, RNA-guided Cas12a2 senses cellular RNA signatures, enabling precise targeting of undruggable mutations. Transcript-activated chromatin shredding provides an innovative approach to precision disease treatments for undruggable targets.

Animals

The DNA replication checkpoint limits Okazaki fragment accumulation to protect and restart stalled forks.

Understanding how DNA replication forks stall and restart and how the DNA replication checkpoint prevents irreversible fork collapse in molecular detail are crucial for understanding how cells maintain stable genomes and how they prevent the genetic instability that drives cancer. Here, we describe the reconstitution of fork stalling and restart with purified budding yeast proteins. After nucleotide depletion, leading-strand DNA synthesis quickly stops but CMG helicase continues to unwind, and Okazaki fragments continue to initiate on the lagging strand. Incomplete Okazaki fragments sequester PCNA, RFC, and DNA polymerases δ and ε, which prevents normal DNA synthesis restart and exposes nascent DNA to nuclease attack. The DNA replication checkpoint restrains fork progression, which limits this sequestration, protecting stalled forks from collapse and ensuring restart.

DNA Replication