Premium
Cruciform DNA structure formed at short inverted repeats: A source of genetic instability in vivo
Author(s) -
Mandke Pooja P,
Kompella Pallavi,
Lu Steve,
Wang Guliang,
Vasquez Karen
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.457.9
Subject(s) - genome instability , inverted repeat , biology , genetics , direct repeat , cruciform , dna , human genome , genome , microbiology and biotechnology , gene , dna damage , history , archaeology
Genomic instability is a major driving force for many human diseases including cancer. Certain mutation “hotspot” regions of the human genome are susceptible to cancer‐associated instability. These regions often co‐localize with repetitive DNA sequences that can adopt alternative structures (i.e. non‐B DNA). One such structure is cruciform DNA which forms at inverted repeat sequences. Short inverted repeats (<100bp) are abundant in the human genome and our laboratory has shown that they are substantially enriched at translocation breakpoints in human cancer genomes. Also, they are mutagenic and stimulate the formation of DNA double strand breaks (DSBs) leading to deletions in mammalian and yeast cells. The DSBs can be caused by fork stalling (i.e. a replication‐dependent mechanism) or by cleavage of cruciform structures by the repair enzyme XPF (i.e. a replication‐independent mechanism). Together, these studies have provided a mechanistic insight into the role of short inverted repeats in disease etiology. To further delineate the biological significance of these sequences, we have developed a transgenic mouse model containing human inverted repeats. We hypothesize that short inverted repeats capable of forming cruciform structures increase genetic instability in vivo . To test this, we have introduced a recoverable mutation‐reporter shuttle vector, carrying either a GC‐rich short inverted repeat (GC mice) or B‐DNA‐forming sequence (control mice) into the mouse genome. Both male and female GC‐containing mice (n=7) and control mice (n=9) were aged for 2 years and the shuttle‐vector was subsequently recovered from the genomic DNA of spleen tissue. Transformation into competent cells was performed to obtain blue (wild‐type) and white (mutant) colonies. Mutation frequencies were calculated and mutation spectra were obtained by direct DNA sequencing. Preliminary data reveals that GC rich cruciform‐forming sequences induce a significantly higher mutation frequency than the control B‐DNA‐forming sequences. These preliminary results suggest that cruciform‐forming sequences contribute to genetic instability in vivo . The contribution of this study to cancer etiology is significant, as the results provide insights into the molecular changes induced by cruciform structures. Support or Funding Information NIH/NCI support to KMV (CA193124 and CA093729) This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .