Transgenic overexpression of the adenine nucleotide translocase 1 protects cardiomyocytes against TGF尾₁-induced apoptosis by stabilization of the mitochondrial permeability transition pore

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• 作者：J. Heger^a ; ^{Jacqueline.Heger@ugcvr.de} ; Y. Abdallah^a ; T. Shahzad^a ; I. Klumpe^b ; ^c ; H.M. Piper^d ; H.-P. Schultheiss^b ; K.-D. Schlü ; ter^a ; R. Schulz^a ; G. Euler^a ; A. D&ouml ; rner^b
• 关键词：ANT ; adenine nucleotide translocase ; TGF尾 ; transforming growth factor 尾 ; MPTP ; Mitochondrial permeability transition pore ; 螖蠄m ; mitochondrial membrane potential ; SMAD ; small mothers against decapentaplegic ; WT ; Wild-type
• 刊名：Journal of Molecular and Cellular Cardiology
• 出版年：2012
• 期刊代码：171_00222828
• 类别：bio
• 出版时间：July, 2012
• 卷：53
• 期：1
• 页码：73-81
• 文件大小：498 K

摘要

Aims

Since adenine nucleotide translocase 1 (ANT1) overexpression improved cardiac function in rats with activated renin-angiotensin system (RAS) and angiotensin II is known to enhance transforming growth factor 尾 (TGF尾) signaling in cardiomyocytes, we assumed that ANT1 might modulate the classical TGF尾/SMAD pathway. We therefore investigated whether the cardioprotective effect of ANT1 overexpression suppresses TGF尾₁-induced apoptosis, whether mitochondrial permeability transition pore (MPTP) regulation is involved, and SMAD signaling pathway is affected.

Methods and results

Ventricular cardiomyocytes isolated from wild-type (WT) and ANT1 transgenic rats were treated with the apoptosis-inducing agent TGF尾₁ (1 ng/ml). TGF尾₁ treatment of WT cells enhanced the number of apoptotic cells by 31.8 卤 11.7%(p < 0.01 vs. WT) measured by chromatin condensation. Apoptosis was blocked by 1 渭M cyclosporine A and by ANT1 overexpression. The protecting effect of ANT1 overexpression on TGF尾₁鈥恑nduced apoptosis was verified by reduced caspase 3/7 activity and increased Bcl-2 expression. In addition, TGF尾₁ decreased mitochondrial membrane potential as measured by JC-1 staining by 18.0 卤 3.7%in WT cardiomyocytes, but only by 7.2 卤 2.8%(p < 0.05 vs. WT) in ANT1 cardiomyocytes. Cyclosporine A also attenuated the decline in mitochondrial membrane potential under TGF尾₁ in WT cardiomyocytes. Determination of MPTP opening by Calcein assay in isolated cardiomyocytes and calcium retention assay in isolated mitochondria revealed a reduced open probability of MPTP after ANT1 overexpression. In addition to the effects of ANT1 on MPTP opening we investigated if ANT1 may interfere with the classical TGF尾 signaling pathway. Interestingly, ANT1-transgenic cardiomyocytes expressed less TGF尾 receptor II than WT cells. However, SMAD2 phosphorylation was already enhanced without TGF尾₁ stimulation in these cells. Although no additional increase in SMAD2 phosphorylation was detectable after TGF尾₁ treatment, SMAD signaling was still responsive to TGF尾₁ indicated by an upregulation of SMAD7, a TGF尾₁ target protein.

Conclusion

Heart-specific overexpression of ANT1 leads to a reduced apoptotic response to TGF尾₁ by preservation of the mitochondrial membrane potential, resistance to MPTP opening and altered TGF尾 signaling.