Specific Inhibition of NEIL-initiated Repair of Oxidized Base Damage in Human Genome by Copper and Iron

Muralidhar, L. Hegde and Pavana, M. Hegde and Holthauzen, Luis M. F. and Tapas, K. Hazra and Jagannatha Rao, K. S. (2010) Specific Inhibition of NEIL-initiated Repair of Oxidized Base Damage in Human Genome by Copper and Iron. Journal of Biological Chemistry, 285 (37). pp. 28812-28825.

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Abstract

Dyshomeostasis of transition metals iron and copper as well as accumulation of oxidative DNA damage have been implicated in multitude of human neurodegenerative diseases, including Alzheimer disease and Parkinson disease. These metals oxidize DNA bases by generating reactive oxygen species. Most oxidized bases in mammalian genomes are repaired via the base excision repair pathway, initiated with one of four major DNA glycosylases: NTH1 or OGG1 (of the Nth family) or NEIL1 or NEIL2 (of the Nei family). Here we show that Fe(II/III) and Cu(II) at physiological levels bind to NEIL1 and NEIL2 to alter their secondary structure and strongly inhibit repair of mutagenic 5-hydroxyuracil, a common cytosine oxidation product, both in vitro and in neuroblastoma (SH-SY5Y) cell extract by affecting the base excision and AP lyase activities of NEILs. The specificity of iron/copper inhibition of NEILs is indicated by a lack of similar inhibition of OGG1, which also indicated that the inhibition is due to metal binding to the enzymes and not DNA. Fluorescence and surface plasmon resonance studies show submicromolar binding of copper/iron to NEILs but not OGG1. Furthermore, Fe(II) inhibits the interaction of NEIL1 with downstream base excision repair proteins DNA polymerase β and flap endonuclease-1 by 4–6-fold. These results indicate that iron/copper overload in the neurodegenerative diseases could act as a double-edged sword by both increasing oxidative genome damage and preventing their repair. Interestingly, specific chelators, including the natural chemopreventive compound curcumin, reverse the inhibition of NEILs both in vitro and in cells, suggesting their therapeutic potential.

Item Type:	Article
Uncontrolled Keywords:	CopperDNA DamageDNA Repair Iron Neurodegeneration Base Excision Repair DNA Glycosylase NEIL1NEIL2 Oxidative DNA Damage Curcumin Dyshomeostasis Neuroprotection
Subjects:	500 Natural Sciences and Mathematics > 07 Life Sciences > 03 Biochemistry & Molecular Biology
Divisions:	Dept. of Biochemistry
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	05 Aug 2011 10:05
Last Modified:	05 Aug 2011 10:05
URI:	http://ir.cftri.res.in/id/eprint/10409

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