Fragmentation of human heart mitochondrial DNA associated with premature aging.
Point mutations, oxygen damage and deletions in the heart mitochondrial (mt) DNA of a 19-year-old male patient with premature aging, who died of mitochondrial cardiomyopathy, were comprehensively analyzed. With total base-sequencing, one syn- mutation in the tRNA(Asp) gene and one mit-mutation in the ND3 gene were demonstrated. Using microHPLC/MS, 0.20% of the total deoxyguanosine (dG) were proved to be converted into its hydroxy-radical adduct, 8-hydroxy-dG, of which amount corresponds to that in normal subjects of 78 years old. The total detection system for mtDNA deletions, using 180 kinds of primer pairs, revealed extensive fragmentation of mtDNA; 235 types of deletions existed with various sizes, 97 of which yielded mtDNA minicircles lacking both of the replication origins of light- and heavy-strands. Deleted mtDNA accounted for 84% of the total mtDNA. In a man died from an accident at age 28 having almost the same mtDNA genotype except syn-, 50 types of deleted mtDNA, accounting for 15% of the total, were detected in his heart mtDNA. These results will present a clue to an unidentified mechanism of somatic mtDNA replication and the molecular basis of aging heart.
Department of Biomedical Chemistry, Faculty of Medicine, University of Nagoya, Japan.
K
K
Katsumata
M
M
Hayakawa
M
M
Tanaka
S
S
Sugiyama
T
T
Ozawa
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000328:Adult; D000375:Aging / Q000378:metabolism*; D001483:Base Sequence; D009202:Cardiomyopathies / Q000235:genetics* / Q000378:metabolism; D004249:DNA Damage; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000032:analysis; D006321:Heart / Q000254:growth & development*; D006801:Humans; D008297:Male; D008929:Mitochondria, Heart / Q000378:metabolism*; D008969:Molecular Sequence Data; D017354:Point Mutation; D017384:Sequence Deletion
D004272:DNA, Mitochondrial; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003849:Deoxyguanosine