Therese Hourani
Research Mentor(s): Agnieszka Lukaszewicz
Mentor Department: Human Genetics
Authors: Therese Hourani, Lindsey Bray, Kirsten Warcup, Agnieszka Lukaszewicz
Session: Session 4 (1:00pm – 1:50pm)
Presentation Type: Poster 90
Abstract
During meiosis, double-strand breaks (DSBs) are formed by the evolutionarily conserved SPO11 protein to initiate meiotic recombination, the DNA exchange between homologous chromosomes (Keeney, 2011; Lukaszewicz et al., 2018). Although meiotic DSBs are essential for reproduction and contribute to the genetic variation of offspring, they are also mutagenic. Specifically, adjacent DSBs, known as “double cuts”, can be repaired by nonhomologous end-joining (NHEJ), leading to deletions (Lukaszewicz et al., 2021). In addition, DNA fragments released by double-cutting can also be circularized (Lukaszewicz et al., 2021). Here, we predict that double cutting can lead to inversions via re-insertion of DNA fragments in the opposite direction. Further, we hypothesize that in the absence of MRE11, these events may be more frequent because of resection defects observed in Mre11 mutant mice that may promote end joining. MRE11, a component of the MRN complex, resects DSB ends, resulting in the release of SPO11 oligos and 3′ single-stranded DNA overhangs necessary for strand invasion and DSB repair. In this experiment, we detect inversions of double-cut fragments in testis DNA from Mre11 mutant and wild-type mice by nested PCR, with primers designed to amplify these events. We will determine the frequency and distribution of inversions to better understand the mechanism by which these mutational outcomes arise and contribute to germline mutagenesis.
