Loss of Neil3, the major DNA glycosylase activity for removal of hydantoins in single stranded DNA, reduces cellular proliferation and sensitizes cells to genotoxic stress

Abstract

7,8-Dihydro-8-oxoguanine (8-oxoG) is one of the most common oxidative base lesions in normal tissues induced by a variety of endogenous and exogenous agents. Hydantoins are products of 8-oxoG oxidation and as 8-oxoG, they have been shown to be mutagenic lesions. Oxidative DNA damage has been implicated in the etiology of various age-associated pathologies, such as cancer, cardiovascular diseases, arthritis, and several neurodegenerative diseases. The mammalian endonuclease VIII-like 3 (Neil3) is one of the four DNA glycosylases found to recognize and remove hydantoins in the first step of base excision repair (BER) pathway. We have generated mice lacking Neil3 and by using total cell extracts we demonstrate that Neil3 is the main DNA glycosylase that incises hydantoins in single stranded DNA in tissues. Using the neurosphere culture system as a model to study neural stem/progenitor (NSPC) cells we found that lack of Neil3 impaired self renewal but did not affect differentiation capacity. Proliferation was also reduced in mouse embryonic fibroblasts (MEFs) derived from Neil3(-/-) embryos and these cells were sensitive to both the oxidative toxicant paraquat and interstrand cross-link (ICL)-inducing agent cisplatin. Our data support the involvement of Neil3 in removal of replication blocks in proliferating cells.

Replication-Dependent Unhooking of DNA Interstrand Cross-Links by the NEIL3 Glycosylase

“…This feature of cisplatin-ICLs might result from the massive distortion of the DNA induced by the lesion. It should be noted that Neil3 -nullizygous MEFs exhibit modest sensitivity to cisplatin (Rolseth et al, 2013), suggesting that a portion of cisplatin-ICLs may be processed by NEIL3 in cells. More ICLs will have to be examined to determine whether the degree of distortion is a primary factor in determining pathway choice.…”

Expression signatures of DNA repair genes correlate with survival prognosis of astrocytoma patients

“…39,40 Accordingly, Takao et al 38 demonstrated that an Escherichia coli strain double mutated for Nth and Nei presents higher sensibility to ROS, and when Neil3 is overexpressed, the resistance was partially recovered. Similarly, Rolseth et al 41 demonstrated that the primary mouse embryonic fibroblast (MEFs), obtained from Neil3 knockout mouse, presented higher sensibility to the genotoxic agents cisplatin and paraquat, when compared to MEFs with normal expression of Neil3. Once secondary DNA damage inflicted from IR is promoted by ROS, our data suggest that similar to Takao et al 38 and Rolseth et al, 41 NEIL3 could play an important role in the resistance of GBM cells to this type of genotoxic stress.…”

Removal of oxidatively generated DNA damage by overlapping repair pathways

“…The Sp and Gh lesions in double-stranded DNA are good substrates of BER enzymes in vitro that include the bifunctional DNA glycosylases E. coli Fpg [102], Nei [103], mammalian NEIL1 and NEIL2 [78], NEIL3 [79, 104–106], human NEIL1 [71, 72], and human NEIL3 [80]. These hydantoins, are also repaired by the prokaryotic NER pathways initiated by UvrABC proteins in vitro [107].…”