Hat Assay Archives - Gen9 Genetics
The formation of highly stable four-stranded DNA, called G-quadruplex (G4), promotes site-specific genome instability. G4 DNA structures fold from repetitive guanine sequences, and growing experimental evidence connects G4 sequence motifs with specific gene rearrangements. The human TCF3 gene (also called E2A) is subject to genetic instability associated with severe disease, especially a common t (1; 19) translocation event associated with acute lymphoblastic leukemia.
The sites of instability in TCF3 are not randomly distributed, but rather are focused on certain sequences. We asked if the formation of G4 DNA could explain why TCF3 is prone to recombination and mutagenesis. Here we demonstrate that the sequences surrounding the major t (1; 19) break site and a region associated with copy number variations contain both G4 sequence motifs. The identified motifs readily adopt G4 DNA structures that are stable enough to interfere with DNA synthesis under physiological saline conditions in vitro. When introduced into the yeast genome, TCF3 G4 motifs promoted large chromosomal rearrangements in a transcription-dependent manner. Our results provide a molecular rationale for site-specific instability of human TCF3, suggesting that G4 DNA structures contribute to oncogenic DNA breaks and recombination.
The formation of highly stable four-stranded DNA, called G-quadruplex (G4), promotes site-specific genome instability. G4 DNA structures fold from repetitive guanine sequences, and growing experimental evidence connects G4 sequence motifs with specific genetic rearrangements. The human transcription factor 3 (TCF3) gene (alsotermed E2A) is subject to genetic instability associated with severe disease, most notably a common t (1; 19) translocation event associated with acute lymphoblasticleukemia.
The sites of instability in TCF3 are not randomly distributed, but rather are concentrated in certain sequences. We asked if the formation of G4 DNA could explain why TCF3 is prone to recombination and mutagenesis. Here we demonstrate that the sequences surrounding the major t (1; 19) break site and a region associated with copy number variations contain both G4 sequence motifs. The identified motifs readily adopt G4 DNA structures that are stable enough to interfere with DNA synthesis under physiological saline conditions in vitro. When introduced into the yeast genome, TCF3 G4 motifs promoted macroscopic chromosomal rearrangements in a transcription-dependent manner. Our results provide a molecular rationale for site-specific instability of human TCF3, suggesting that G4DNA structures contribute to oncogenic DNA breaks and recombination.