Inhibition of endogenous thioredoxin in the heart increases oxidative stress and cardiac hypertrophy
Mitsutaka Yamamoto, … , Stephen F. Vatner, Junichi Sadoshima
Mitsutaka Yamamoto, … , Stephen F. Vatner, Junichi Sadoshima
Published November 1, 2003
Citation Information: J Clin Invest. 2003;112(9):1395-1406. https://doi.org/10.1172/JCI17700.
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Article Cardiology

Inhibition of endogenous thioredoxin in the heart increases oxidative stress and cardiac hypertrophy

Abstract

Thioredoxin 1 (Trx1) has redox-sensitive cysteine residues and acts as an antioxidant in cells. However, the extent of Trx1 contribution to overall antioxidant mechanisms is unknown in any organs. We generated transgenic mice with cardiac-specific overexpression of a dominant negative (DN) mutant (C32S/C35S) of Trx1 (Tg-DN-Trx1 mice), in which the activity of endogenous Trx was diminished. Markers of oxidative stress were significantly increased in hearts from Tg-DN-Trx1 mice compared with those from nontransgenic (NTg) mice. Tg-DN-Trx1 mice exhibited cardiac hypertrophy with maintained cardiac function at baseline. Intraperitoneal injection of N-2-mercaptopropionyl glycine, an antioxidant, normalized cardiac hypertrophy in Tg-DN-Trx1 mice. Thoracic aortic banding caused greater increases in myocardial oxidative stress and enhanced hypertrophy in Tg-DN-Trx1 compared with NTg mice. In contrast, transgenic mice with cardiac-specific overexpression of wild-type Trx1 did not show cardiac hypertrophy at baseline but exhibited reduced levels of hypertrophy and oxidative stress in response to pressure overload. These results demonstrate that endogenous Trx1 is an essential component of the cellular antioxidant mechanisms and plays a critical role in regulating oxidative stress in the heart in vivo. Furthermore, inhibition of endogenous Trx1 in the heart primarily stimulates hypertrophy, both under basal conditions and in response to pressure overload through redox-sensitive mechanisms.

Authors

Mitsutaka Yamamoto, Guiping Yang, Chull Hong, Jing Liu, Eric Holle, Xianzhong Yu, Thomas Wagner, Stephen F. Vatner, Junichi Sadoshima

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(a) Heart homogenates were prepared from Tg-DN-Trx1 and NTg mice. Immuno...
(a) Heart homogenates were prepared from Tg-DN-Trx1 and NTg mice. Immunoblot analyses were conducted using anti-hTrx1 Ab. Short (15-second) and long (5-minute) exposures of the immunoblot are shown. After long exposure, endogenous mouse Trx1 was detected. Note that the anti-hTrx1 Ab (clone 2G11) does not detect mouse Trx1 as efficiently as it detects hTrx1. (b) Tissue homogenates were prepared from various organs. Immunoblot analyses were conducted using anti-hTrx1 Ab. (c) RT-PCR analyses of Trx1 and GAPDH. Total RNA was extracted from Tg-DN-Trx1 (line no. 13) and NTg mice. The lower left panel indicates protein expression of total Trx1, determined using anti-hTrx1 Ab (clone 4H9), which detects both mouse Trx1 and hTrx1. (d) The disulfide oxidoreductase activity of Trx was determined by the insulin reduction assay. Time-dependent reduction of NADPH, determined by spectrophotometry, is shown. *P < 0.01 compared with NTg. #P < 0.05, ##P < 0.01 compared with 0 min.