Single‐strand annealing: Molecular mechanisms and potential applications in CRISPR‐Cas‐based precision genome editing

Abstract

Background: Spontaneous double-stranded DNA breaks (DSBs) frequently occur within the genome of all living organisms and must be well repaired for survival.Recently, more important roles of the DSB repair pathways that were previously thought to be minor pathways, such as single-strand annealing (SSA), have been shown.Nevertheless, the biochemical mechanisms and applications of the SSA pathway in genome editing have not been updated. Purpose and Scope:Understanding the molecular mechanism of SSA is important to design potential applications in gene editing. This review provides insights into the recent progress of SSA studies and establishes a model for their potential applications in precision genome editing. Summary and Conclusion:The SSA mechanism involved in DNA DSB repair appears to be activated by a complex signaling cascade starting with broken end sensing and 5′-3′ resection to reveal homologous repeats on the 3′ ssDNA overhangs that flank the DSB. Annealing the repeats would help to amend the discontinuous ends and restore the intact genome, resulting in the missing of one repeat and the intervening sequence between the repeats. We proposed a model for CRISPR-Cas-based precision insertion or replacement of DNA fragments to take advantage of the characteristics. The proposed model can add a tool to extend the choice for precision gene editing. Nevertheless, the model needs to be experimentally validated and optimized with SSA-favorable conditions for practical applications.

BMN673 Is a PARP Inhibitor with Unique Radiosensitizing Properties: Mechanisms and Potential in Radiation Therapy

“…For example, it has been reported that deficiency of ERCC1, a component of the excision nuclease complex (ERCC1-XPF), activated during SSA, results in synthetic lethality after olaparib treatment [ 83 ]. Moreover, reports suggest that PARP-1 modulates the activity of FEN-1; a protein also involved in RAD52-mediated SSA [ 84 , 85 ]. However, as PARP-1, ERCC1-XPF and RAD52 are shown to be involved in multiple DNA repair pathways, this makes it difficult to establish specific roles of PARP-1 in SSA.…”

The effect of repeat length on Marcal1-dependent single-strand annealing in Drosophila

“…Prior studies have identified proteins involved in SSA in fungi, invertebrates, and mammalian cell lines (reviewed in Bhargava et al 2016 ; Vu et al 2022 ). Studies in budding yeast found that loss of Rad52 or its paralog Rad59 resulted in near complete ablation of SSA ( Sugawara and Haber 1992 ; Ivanov et al 1996 ; Sugawara et al 2000 ).…”

The Effect of Repeat Length on Marcal1-Dependent Single-Strand Annealing in Drosophila

“…Prior studies have identified proteins involved in SSA in fungi, invertebrates, and mammalian cell lines (reviewed in BHARGAVA et al 2016;VU et al 2022). Studies in budding yeast found that loss of Rad52 or its paralog Rad59 resulted in near complete ablation of SSA (SUGAWARA AND HABER 1992;IVANOV et al 1996;SUGAWARA et al 2000).…”

“…Prior studies have identified proteins involved in SSA in fungi, invertebrates, and mammalian cell lines (reviewed in B hargava et al . 2016; V u et al . 2022).…”