PSIP1/LEDGF reduces R-loops at transcription sites to maintain genome integrity.

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• R-loops, RNA-DNA hybrids, can threaten genome integrity when accumulating at transcription sites.
• PSIP1 is a chromatin protein involved in transcription, RNA processing, and DNA repair.
• Understanding PSIP1's role in R-loop homeostasis is crucial for genome stability.

Purpose of the Study:

• To investigate the role of PSIP1 in R-loop homeostasis and genome integrity.
• To elucidate the mechanism by which PSIP1 prevents R-loop-induced DNA damage.
• To assess the impact of PSIP1 depletion on DNA repair pathways and cancer cell sensitivity to therapies.

Main Methods:

• Genome-wide mapping of PSIP1, R-loops, and γ-H2AX in PSIP1-depleted human and mouse cell lines.
• Analysis of DNA damage markers (53BP1, RAD51 foci) and cell sensitivity to DNA-damaging agents and PARP1 inhibitors.

Main Results:

• PSIP1 depletion leads to R-loop accumulation and DNA damage at gene promoters.
• R-loop accumulation causes transcriptional arrest and transcription-replication conflicts.
• PSIP1 depletion alters DNA repair choice and increases cancer cell sensitivity to PARP1 inhibitors and DNA-damaging agents.

Conclusions:

• PSIP1 plays a critical role in maintaining genome integrity by resolving R-loops at transcription sites.
• PSIP1 influences DNA repair pathway selection in response to R-loop-induced damage.
• Targeting PSIP1 or related pathways may offer therapeutic strategies for cancer treatment.