Jm. Wang et al., Dilated cardiomyopathy and atrioventricular conduction blocks induced by heart-specific inactivation of mitochondrial DNA gene expression, NAT GENET, 21(1), 1999, pp. 133-137
Mutations of mitochondrial DNA (mtDNA) cause several well-recognized human
genetic syndromes with deficient oxidative phosphorytation(1-4) and may als
o have a role in ageing and acquired diseases of old age(5). We report here
that hallmarks of mtDNA mutation disorders can be reproduced in the mouse
using a conditional mutation strategy tl manipulate the expression of the g
ene encoding mitochondrial transcription factor A (Tfam, previously named m
tTFA), which regulates transcription and replication of mtDNA (refs 6,7). U
sing a loxP-flanked Tfam allele (Tfam(loxP); ref. 8) in combination with a
cre-recombinase transgene under control of the muscle creatinine kinase pro
moter(9,10), we have disrupted Tfam in heart and muscle. Mutant animals dev
elop a mosaic cardiac-specific progressive respiratory chain deficiency, di
lated cardiomyopathy, atrioventricular heart conduction blocks and die at 2
-4 weeks of age. This animal model reproduces biochemical, morphological an
d physiological features of the dilated cardiomyopathy of Kearns-Sayre synd
rome(1-4). Furthermore, our findings provide genetic evidence that the resp
iratory chain is critical for normal heart function.