The metabolic syndrome resulting from a knockout of the NEIL1 DNA glycosylase

doi:10.1073/pnas.0507444103

The metabolic syndrome resulting from a knockout of the NEIL1 DNA glycosylase

*Center for Research on Occupational and Environmental Toxicology and Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239;
^†Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555;
^‡Department of Pathology, University of Alabama, Birmingham, AL 35294; and
^§Department of Pathology and Oregon Cancer Institute, Oregon Health & Science University, Portland, OR 97239

Edited by Aziz Sancar, University of North Carolina School of Medicine, Chapel Hill, NC, and approved December 13, 2005 (received for review August 26, 2005)

Abstract

Endogenously formed reactive oxygen species continuously damage cellular constituents including DNA. These challenges, coupled with exogenous exposure to agents that generate reactive oxygen species, are both associated with normal aging processes and linked to cardiovascular disease, cancer, cataract formation, and fatty liver disease. Although not all of these diseases have been definitively shown to originate from mutations in nuclear DNA or mitochondrial DNA, repair of oxidized, saturated, and ring-fragmented bases via the base excision repair pathway is known to be critical for maintaining genomic stability. One enzyme that initiates base excision repair of ring-fragmented purines and some saturated pyrimidines is NEIL1, a mammalian homolog to Escherichia coli endonuclease VIII. To investigate the organismal consequences of a deficiency in NEIL1, a knockout mouse model was created. In the absence of exogenous oxidative stress, neil1 knockout (neil1 ^−/−) and heterozygotic (neil1 ^+/−) mice develop severe obesity, dyslipidemia, and fatty liver disease and also have a tendency to develop hyperinsulinemia. In humans, this combination of clinical manifestations, including hypertension, is known as the metabolic syndrome and is estimated to affect >40 million people in the United States. Additionally, mitochondrial DNA from neil1 ^−/− mice show increased levels of steady-state DNA damage and deletions relative to wild-type controls. These data suggest an important role for NEIL1 in the prevention of the diseases associated with the metabolic syndrome.

Footnotes

^¶To whom correspondence should be addressed at:
Oregon Health & Science University, 2598 CROET Building, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239-3098.
E-mail: lloydst{at}ohsu.edu
Author contributions: T.G.W., J.D.C., S.W.B., A.K.M., and R.S.L. designed research; V.V., B.L., T.G.W., J.D.C., S.G., and C.L.C. performed research; V.V., B.L., I.G.M., T.G.W., J.D.C., S.G., S.W.B., C.L.C., A.K.M., and R.S.L. analyzed data; and I.G.M., T.G.W., J.D.C., S.W.B., C.L.C., A.K.M., and R.S.L. wrote the paper.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office.
Freely available online through the PNAS open access option.
Abbreviations:

ROS,

reactive oxygen species;

BER,

base excision repair;

KO,

knockout;

QPCR,

quantitative PCR;

PPAR,

peroxisome proliferator-activated receptor.
Freely available online through the PNAS open access option.