Overexpression of mitochondrial transcription factor a ameliorates mitochondrial deficiencies and cardiac failure after myocardial infarction.
BACKGROUND
Mitochondrial DNA (mtDNA) copy number is decreased not only in mtDNA-mutation diseases but also in a wide variety of acquired degenerative and ischemic diseases. Mitochondrial transcription factor A (TFAM) is essential for mtDNA transcription and replication. Myocardial mtDNA copy number and TFAM expression both decreased in cardiac failure. However, the functional significance of TFAM has not been established in this disease state.


RESULTS
We have now addressed this question by creating transgenic (Tg) mice that overexpress human TFAM gene and examined whether TFAM could protect the heart from mtDNA deficiencies and attenuate left ventricular (LV) remodeling and failure after myocardial infarction (MI) created by ligating the left coronary artery. TFAM overexpression could ameliorate the decrease in mtDNA copy number and mitochondrial complex enzyme activities in post-MI hearts. Survival rate during 4 weeks of MI was significantly higher in Tg-MI than in wild-type (WT) littermates (WT-MI), although infarct size was comparable. LV cavity dilatation and dysfunction were significantly attenuated in Tg-MI. LV end-diastolic pressure was increased in WT-MI, and it was also reduced in Tg-MI. Improvement of LV function in Tg-MI was accompanied by a decrease in myocyte hypertrophy, apoptosis, and interstitial fibrosis as well as oxidative stress in the noninfarcted LV.


CONCLUSIONS
Overexpression of TFAM inhibited LV remodeling after MI. TFAM may provide a novel therapeutic strategy of cardiac failure.
Ikeuchi
Masaki
M
Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Matsusaka
Hidenori
H
Kang
Dongchon
D
Matsushima
Shouji
S
Ide
Tomomi
T
Kubota
Toru
T
Fujiwara
Toshiyuki
T
Hamasaki
Naotaka
N
Takeshita
Akira
A
Sunagawa
Kenji
K
Tsutsui
Hiroyuki
H
D000818:Animals; D003433:Crosses, Genetic; D004261:DNA Replication; D004272:DNA, Mitochondrial / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation; D006333:Heart Failure / Q000503:physiopathology / Q000517:prevention & control*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008929:Mitochondria, Heart / Q000201:enzymology / Q000235:genetics; D028361:Mitochondrial Diseases / Q000503:physiopathology / Q000517:prevention & control*; D024101:Mitochondrial Proteins / Q000235:genetics*; D009203:Myocardial Infarction / Q000150:complications* / Q000503:physiopathology; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; D014157:Transcription Factors; C422562:mitochondrial transcription factor A