RECQL5 Controls Transcript Elongation and Suppresses Genome Instability Associated with Transcription Stress

Summary RECQL5 is the sole member of the RECQ family of helicases associated with RNA polymerase II (RNAPII). We now show that RECQL5 is a general elongation factor that is important for preserving genome stability during transcription. Depletion or overexpression of RECQL5 results in corresponding shifts in the genome-wide RNAPII density profile. Elongation is particularly affected, with RECQL5 depletion causing a striking increase in the average rate, concurrent with increased stalling, pausing, arrest, and/or backtracking (transcription stress). RECQL5 therefore controls the movement of RNAPII across genes. Loss of RECQL5 also results in the loss or gain of genomic regions, with the breakpoints of lost regions located in genes and common fragile sites. The chromosomal breakpoints overlap with areas of elevated transcription stress, suggesting that RECQL5 suppresses such stress and its detrimental effects, and thereby prevents genome instability in the transcribed region of genes.
Graphical Abstract
Highlights • RECQL5 is a general RNAPII elongation factor • RECQL5 reduces the elongation rate while decreasing pausing and arrest events • Loss of RECQL5 results in genome instability in genes and at common fragile sites • Incidents of genome instability colocalize with pause and arrest events
Rapid elongation by RNA polymerase II leads to increased transcriptional stress including a high incidence of pausing and arrests, which correlates with sites of genomic instability. RECQL5 modulates the rate of transcription, mitigating both the stress and instability effects.