Double-strand break repair model

Various pathways for double-strand break repair. NHEJ in this article refers to cNHEJ. MMEJ in this article refers to a-EJ.

A double-strand break repair model refers to the various models of pathways that cells undertake to repair double strand-breaks (DSB). DSB repair is an important cellular process, as the accumulation of unrepaired DSB could lead to chromosomal rearrangements, tumorigenesis or even cell death.[1] In human cells, there are two main DSB repair mechanisms: Homologous recombination (HR) and non-homologous end joining (NHEJ). HR relies on undamaged template DNA as reference to repair the DSB, resulting in the restoration of the original sequence.[2] NHEJ modifies and ligates the damaged ends regardless of homology.[2] In terms of DSB repair pathway choice, most mammalian cells appear to favor NHEJ rather than HR. This is because the employment of HR may lead to gene deletion or amplification in cells which contains repetitive sequences.[1] In terms of repair models in the cell cycle, HR is only possible during the S and G2 phases, while NHEJ can occur throughout whole process.[3] These repair pathways are all regulated by the overarching DNA damage response mechanism.[4] Besides HR and NHEJ, there are also other repair models which exists in cells. Some are categorized under HR, such as synthesis-dependent strain annealing, break-induced replication, and single-strand annealing; while others are an entirely alternate repair model, namely, the pathway microhomology-mediated end joining (MMEJ).[5]

  1. ^ a b Featherstone C, Jackson SP (October 1999). "DNA double-strand break repair". Current Biology. 9 (20): R759–R761. Bibcode:1999CBio....9.R759F. doi:10.1016/S0960-9822(00)80005-6. PMID 10531043. S2CID 1941783.
  2. ^ a b Mao Z, Bozzella M, Seluanov A, Gorbunova V (October 2008). "Comparison of nonhomologous end joining and homologous recombination in human cells". DNA Repair. 7 (10): 1765–1771. doi:10.1016/j.dnarep.2008.06.018. PMC 2695993. PMID 18675941.
  3. ^ Scully R, Panday A, Elango R, Willis NA (November 2019). "DNA double-strand break repair-pathway choice in somatic mammalian cells". Nature Reviews. Molecular Cell Biology. 20 (11): 698–714. doi:10.1038/s41580-019-0152-0. PMC 7315405. PMID 31263220.
  4. ^ Cite error: The named reference :15 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference :14 was invoked but never defined (see the help page).