Somatic mitochondrial DNA mutations in single neurons and glia.
Somatic mitochondrial DNA (mtDNA) point mutations reach high levels in the brain. However, the cell types that accumulate mutations and the patterns of mutations within individual cells are not known. We have quantified somatic mtDNA mutations in 28 single neurons and in 18 single glia from post-mortem human substantia nigra of six control subjects. Both neurons and glia contain mtDNA with somatic mutations. Single neurons harbor a geometric mean (95% CI) of 200.3 (152.9-262.4) somatic mtDNA point mutations per million base pairs, compared to 133.8 (97.5-184.9) for single glia (p=0.0251). If mutations detected multiple times in the same cell are counted only once, the mean mutation level per million base pairs remains elevated in single neurons (146.9; 124.0-174.2) compared to single glia (100.5; 81.5-126.5; p=0.009). Multiple distinct somatic point mutations are present in different cells from the same subject. Most of these mutations are individually present at low levels (less than 10-20% of mtDNA molecules), but with high aggregate mutation levels, particularly in neurons. These mutations may contribute to changes in brain function during normal aging and neurodegenerative disorders.
Cantuti-Castelvetri
Ippolita
I
Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02129, USA.
Lin
Michael T
MT
Zheng
Kangni
K
Keller-McGandy
Christine E
CE
Betensky
Rebecca A
RA
Johns
Donald R
DR
Beal
M Flint
MF
Standaert
David G
DG
Simon
David K
DK
D000328:Adult; D000368:Aged; D000544:Alzheimer Disease / Q000235:genetics / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D016022:Case-Control Studies; D002452:Cell Count; D003001:Cloning, Molecular / Q000379:methods; D016001:Confidence Intervals; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D042282:Microdissection / Q000379:methods; D008875:Middle Aged; D008954:Models, Biological; D009457:Neuroglia / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D017354:Point Mutation / Q000235:genetics*; D011180:Postmortem Changes; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
D004272:DNA, Mitochondrial