Voltage-dependent anion channel (VDAC) is involved in apoptosis of cell lines carrying the mitochondrial DNA mutation.
BACKGROUND
The mitochondrial voltage-dependent anion channel (VDAC) is increasingly implicated in the control of apoptosis. We have studied the effects the mitochondrial DNA (mtDNA) tRNAIle mutation on VDAC expression, localization, and apoptosis.


METHODS
Lymphoblastoid cell lines were derived from 3 symptomatic and 1 asymptomatic members of a family with hypertension associated with the A4263G tRNAIle mutation as well as from control subjects. Mitochondrial potential (DeltaPsim) and apoptosis were measured by flow cytometry; co-localization of VDAC and Bax was evaluated by confocal microscopy.


RESULTS
Expression of VDAC and Bax in mtDNA cell lines was found to be increased compared to controls, while expression of the small conductance calcium-dependant potassium channel (sKCa) was unchanged. Confocal imaging revealed co-localization of VDAC/Bax on the outer mitochondrial membrane of A4263G cell lines but not from controls. Flow cytometry indicated that the mitochondrial potential was decreased by 32% in mutated cells versus controls while rates of apoptosis were increased (P < 0.05). The difference was attenuated by Cyclosporin A (CsA, 2 muM), a blocker of VDAC.


CONCLUSIONS
We conclude that increased expression of mitochondrial VDAC and subcellular co-localization of VDAC/Bax increases mitochondrial permeability and apoptosis in cell lines carrying the mtDNA tRNAIle A4263G mutation.
Yuqi
Liu
L
Institute of Geriatric Cardiology, Chinese PLA General Hospital, Beijing 100853, PR China.
Lei
Gao
G
Yang
Li
L
Zongbin
Li
L
Hua
Xu
X
Lin
Wang
W
Rui
Chen
C
Mohan
Liu
L
Yi
Wen
W
Minxin
Guan
G
Shiwen
Wang
W
D017209:Apoptosis / Q000235:genetics*; D002461:Cell Line, Transformed; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D006801:Humans; D006973:Hypertension / Q000235:genetics* / Q000503:physiopathology; D008214:Lymphocytes; D008297:Male; D008564:Membrane Potentials; D018613:Microscopy, Confocal; D009154:Mutation; D010375:Pedigree; D050994:Voltage-Dependent Anion Channels / Q000235:genetics*; D051028:bcl-2-Associated X Protein / Q000235:genetics*
C494826:BAX protein, human; D004272:DNA, Mitochondrial; D050994:Voltage-Dependent Anion Channels; D051028:bcl-2-Associated X Protein