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Homologous recombination is widely used by cells to accurately repair harmful DNA breaks that occur on both strands of DNA, known as double-strand breaks (DSB), in a process called homologous recombinational repair (HRR). [1] Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes ...
Base excision repair, Nucleotide excision repair, Homologous recombination, Non-homologous end joining [25] SIRT6-deficient mice develop profound lymphopenia, loss of subcutaneous fat and lordokyphosis, and these defects overlap with aging-associated degenerative processes [ 26 ]
Homology-directed repair (HDR) is a mechanism in cells to repair double-strand DNA lesions. [1] The most common form of HDR is homologous recombination. The HDR mechanism can only be used by the cell when there is a homologous piece of DNA present in the nucleus, mostly in G2 and S phase of the cell cycle. Other examples of homology-directed ...
[42] [43] Some examples of diseases caused by defects of DSB repair mechanisms are listed below: Fanconi Anemia (FA) and Hereditary breast and ovarian cancer (HBOC) syndrome are caused by defects in homologous recombination. [44] Biallelic mutation of either BRCA1/2 gene results in the loss of homologous recombination activity. [44]
Humans born with inherited defects in DNA repair mechanisms (for example, Li-Fraumeni syndrome) have a higher cancer risk. [89] The prevalence of DNA damage response mutations differs across cancer types; for example, 30% of breast invasive carcinomas have mutations in genes involved in homologous recombination. [84]
Homologous recombination repair [ edit ] In breast , ovarian , pancreatic , and prostate cancers, a core enzyme employed in homologous recombination repair (HRR) of DNA damage is often defective due to LOH, that is genetic defects in both copies (in the diploid human genome) of the gene encoding an enzyme necessary for HRR. [ 8 ]
Melanoma cells are commonly defective in postreplication repair of DNA damages that are in the form of cyclobutane pyrimidine dimers, a type of damage caused by ultraviolet radiation. [11] [12] A particular repair process that appears to be defective in melanoma cells is homologous recombinational repair. [12]
Non-homologous end joining (NHEJ) is a pathway that repairs double-strand breaks in DNA. It is called "non-homologous" because the break ends are directly ligated without the need for a homologous template, in contrast to homology directed repair (HDR), which requires a homologous sequence to guide repair.