Regulation of DNA glycosylases and their role in limiting disease

ArticleinFree Radical Research 46(4):460-78 · February 2012with17 Reads
DOI: 10.3109/10715762.2012.655730 · Source: PubMed
This review will present a current understanding of mechanisms for the initiation of base excision repair (BER) of oxidatively-induced DNA damage and the biological consequences of deficiencies in these enzymes in mouse model systems and human populations.
    • "The accumulation of oxidative DNA damage from both exogenous and endogenous sources have been implicated in the development and progression of several diseases such as cancer, obesity, diabetes, Alzheimer's disease, and others [55][56][57] . PTMs modulate the activity of several DNA repair enzymes and are essential for signaling the presence of DNA damage, thereby maintaining the integrity of the human genome [29]. "
    [Show abstract] [Hide abstract] ABSTRACT: The NEIL1 DNA glycosylase is one of eleven mammalian DNA glycosylases that partake in the first step of the base excision repair (BER) pathway. NEIL1 recognizes and cleaves mainly oxidized pyrimidines from DNA. The past decade has witnessed the identification of an increasing number of post-translational modifications (PTMs) in BER enzymes including phosphorylation, acetylation, and sumoylation, which modulate enzyme function. In this work, we performed the first comprehensive analysis of phosphorylation sites in human NEIL1 expressed in human cells. Mass spectrometry (MS) analysis revealed phosphorylation at three serine residues: S207, S306, and a third novel site, S61. We expressed, purified, and characterized phosphomimetic (glutamate) and phosphoablating (alanine) mutants of the three phosphorylation sites in NEIL1 revealed by the MS analysis. All mutant enzymes were active and bound tightly to DNA, indicating that phosphorylation does not affect DNA binding and enzyme activity at these three serine sites. We also characterized phosphomimetic mutants of two other sites of phosphorylation, Y263 and S269, reported previously, and observed that mutation of Y263 to E yielded a completely inactive enzyme. Furthermore, based on sequence motifs and kinase prediction algorithms, we identified the c-Jun N-terminal kinase 1 (JNK1) as the kinase involved in the phosphorylation of NEIL1. JNK1, a member of the mitogen activated protein kinase (MAPK) family, was detected in NEIL1 immunoprecipitates, interacted with NEIL1 in vitro, and was able to phosphorylate the enzyme at residues S207, S306, and S61.
    Full-text · Article · Aug 2016
    • "Defects in BER enzymes such as those discussed above are associated with neurological disorders and cancer (Sampath, McCullough, & Lloyd, 2012; Wallace, Murphy, & Sweasy, 2012; Wilson, Kim, Berquist, & Sigurdson, 2011). Polymorphic variants of these enzymes have been found in human populations in connection to various cancer incidences (reviewed in Dizdaroglu, 2015). "
    [Show abstract] [Hide abstract] ABSTRACT: Oxidatively induced DNA damage is caused in living organisms by a variety of damaging agents, resulting in the formation of a multiplicity of lesions, which are mutagenic and cytotoxic. Unless repaired by DNA repair mechanisms before DNA replication, DNA lesions can lead to genomic instability, which is one of the hallmarks of cancer. Oxidatively induced DNA damage is mainly repaired by base excision repair pathway with the involvement of a plethora of proteins. Cancer tissues develop greater DNA repair capacity than normal tissues by overexpressing DNA repair proteins. Increased DNA repair in tumors that removes DNA lesions generated by therapeutic agents before they became toxic is a major mechanism in the development of therapy resistance. Evidence suggests that DNA repair capacity may be a predictive biomarker of patient response. Thus, knowledge of DNA-protein expressions in disease-free and cancerous tissues may help predict and guide development of treatments and yield the best therapeutic response. Our laboratory has developed methodologies that use mass spectrometry with isotope dilution for the measurement of expression of DNA repair proteins in human tissues and cultured cells. For this purpose, full-length 15N-labeled analogs of a number of human DNA repair proteins have been produced and purified to be used as internal standards for positive identification and accurate quantification. This chapter describes in detail the protocols of this work. The use of 15N-labeled proteins as internal standards for the measurement of several DNA repair proteins in vivo is also presented.
    Full-text · Chapter · Jul 2015 · Environmental and Molecular Mutagenesis
    • "A brief overview of structure and function of each of these glycosylases is presented below. For more detailed insights into tissue specificities and regulation of these glycosylases, the reader is directed to a recent review [Sampath et al., 2012a] . Mouse models of other BER glycosylases , including the alkyladenine DNA glycosylase (AAG) and uracil DNA glycosylase have also been studied extensively with respect to various pathologies such as cancer and neurodegeneration. "
    [Show abstract] [Hide abstract] ABSTRACT: Cellular components, including nucleic acids, are subject to oxidative damage. If left unrepaired, this damage can lead to multiple adverse cellular outcomes, including increased mutagenesis and cell death. The major pathway for repair of oxidative base lesions is the base excision repair pathway, catalyzed by DNA glycosylases with overlapping but distinct substrate specificities. To understand the role of these glycosylases in the initiation and progression of disease, several transgenic mouse models have been generated to carry a targeted deletion or overexpression of one or more glycosylases. This review summarizes some of the major findings from transgenic animal models of altered DNA glycosylase expression, especially as they relate to pathologies ranging from metabolic disease and cancer to inflammation and neuronal health. Environ. Mol. Mutagen., 2014. © 2014 Wiley Periodicals, Inc.
    Full-text · Article · Dec 2014
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