DNA is the blue print of life and all the information of life processes such as growth, metabolism, reproduction etc are encoded in the sequence of it. Therefore its very important to maintain the genomic integrity of this genetic material, not only to keep away defects in life processes but to pass a faithful information to the next progeny.
Integrity of the DNA is usually challenged by both endogenous and exogenous agents who are capable to induce DNA damage (101). The endogenous DNA damage agents arise from normal cellular metabolism these include Reactive oxygen species or from errors of inaccurate DNA replication (102,103). The exogenous agent who can damage the DNA include various types of radiations, such as Ultraviolet radiation, Ionizing radiation or various mutagenic compounds used in many processes (104). It is hypothesized that every single human cell encounters 104 to 106 DNA lesions every day (105). Thus all cells rely on a correct DNA repair system, which can repair the various type of DNA damage and keeps the genomic integrity of DNA intact.
In order to maintain the genomic stability, cells have evolved a vastly complicated collection of multifactorial process known as DNA damage response [DDR] (106). Collectively these processes ensure to …show more content…
In this pathway, NBS1 functions as an adaptor protein and promotes the phosphorylation of SMC1, which is required for the intra-S phase checkpoint activation after DNA double strand breaks. This branch of the S-phase checkpoint is distinct to the ATM/Chk2/Cdc25A pathway, but is very important for maintaining genomic stability, since cells from Nijmen syndrome patients, display checkpoint defects in S-phase (Yazdi et al,