Neil1 is a genetic modifier of somatic and germline CAG trinucleotide repeat instability in R6/1 mice.
Huntington's disease (HD) is a progressive neurodegenerative disorder caused by trinucleotide repeat (TNR) expansions. We show here that somatic TNR expansions are significantly reduced in several organs of R6/1 mice lacking exon 2 of Nei-like 1 (Neil1) (R6/1/Neil1(-/-)), when compared with R6/1/Neil1(+/+) mice. Somatic TNR expansion is measured by two different methods, namely mean repeat change and instability index. Reduced somatic expansions are more pronounced in male R6/1/Neil1(-/-) mice, although expansions are also significantly reduced in brain regions of female R6/1/Neil1(-/-) mice. In addition, we show that the lack of functional Neil1 significantly reduces germline expansion in R6/1 male mice. In vitro, purified human NEIL1 protein binds and excises 5-hydroxycytosine in duplex DNA more efficiently than in hairpin substrates. NEIL1 excision of cytosine-derived oxidative lesions could therefore be involved in initiating the process of TNR expansion, although other DNA modifications might also contribute. Altogether, these results imply that Neil1 contributes to germline and somatic HD CAG repeat expansion.
Institute of Medical Microbiology, Oslo University Hospital, Rikshospitalet, Sognsvannsveien 20, Oslo, Norway.
Linda
L
Møllersen
Alexander D
AD
Rowe
Jennifer L
JL
Illuzzi
Gunn A
GA
Hildrestrand
Katharina J
KJ
Gerhold
Linda
L
Tveterås
Anja
A
Bjølgerud
David M
DM
Wilson
Magnar
M
Bjørås
Arne
A
Klungland
D000818:Animals; D001483:Base Sequence; D045647:DNA Glycosylases / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D042822:Genomic Instability; D018095:Germ-Line Mutation; D006816:Huntington Disease / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*
D045647:DNA Glycosylases; C481347:Neil1 protein, mouse