The vestigial enzyme D-dopachrome tautomerase protects the heart against ischemic injury
Dake Qi, … , Richard Bucala, Lawrence H. Young
Dake Qi, … , Richard Bucala, Lawrence H. Young
Published July 1, 2014
Citation Information: J Clin Invest. 2014;124(8):3540-3550. https://doi.org/10.1172/JCI73061.
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Research Article Cardiology

The vestigial enzyme D-dopachrome tautomerase protects the heart against ischemic injury

Abstract

The cellular response to stress involves the recruitment and coordination of molecular signaling pathways that prevent cell death. D-dopachrome tautomerase (DDT) is an enzyme that lacks physiologic substrates in mammalian cells, but shares partial sequence and structural homology with macrophage migration inhibitory factor (MIF). Here, we observed that DDT is highly expressed in murine cardiomyocytes and secreted by the heart after ischemic stress. Antibody-dependent neutralization of secreted DDT exacerbated both ischemia-induced cardiac contractile dysfunction and necrosis. We generated cardiomyocyte-specific DDT knockout mice (Myh6-Cre Ddtfl/fl), which demonstrated normal baseline cardiac size and function, but had an impaired physiologic response to ischemia-reperfusion. Hearts from Myh6-Cre Ddtfl/fl mice exhibited more necrosis and LV contractile dysfunction than control hearts after coronary artery ligation and reperfusion. Furthermore, treatment with DDT protected isolated hearts against injury and contractile dysfunction after ischemia-reperfusion. The protective effect of DDT required activation of the metabolic stress enzyme AMP-activated protein kinase (AMPK), which was mediated by a CD74/CaMKK2-dependent mechanism. Together, our data indicate that cardiomyocyte secretion of DDT has important autocrine/paracrine effects during ischemia-reperfusion that protect the heart against injury.

Authors

Dake Qi, Kwame Atsina, Lintao Qu, Xiaoyue Hu, Xiaohong Wu, Bin Xu, Marta Piecychna, Lin Leng, Günter Fingerle-Rowson, Jiasheng Zhang, Richard Bucala, Lawrence H. Young

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Figure 1

Heart-derived DDT has protective autocrine/paracrine effects during ischemia-reperfusion.

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Heart-derived DDT has protective autocrine/paracrine effects during isch...
(A) DDT expression was determined in mouse heart using immunohistochemistry with a polyclonal anti-DDT antibody or nonimmune IgG antibody (as a control for nonspecific staining). Heart LV sections were studied after 20 minutes of ischemia and 3 hours of reperfusion (IR) induced by coronary artery ligation or control sham surgery (CON). Original magnification, ×10. (B) Cardiac DDT release into the coronary venous effluent was quantified by ELISA in ex vivo perfused hearts, during either normal baseline perfusion or global ischemia (15 minutes) and 30 minutes of reperfusion. (C) DDT immunoblots of heart homogenates from mice subjected to 20 minutes of ischemia and 3 hours of reperfusion or sham surgery (Baseline). (D) Cardiac contractile function (LVDP•HR index) in isolated mouse hearts treated with anti-DDT or nonimmune control IgG prior to 15 minutes of ischemia and 30 minutes of reperfusion. (E) Myocardial necrosis, determined by vital staining with TTC and expressed as the infarct area as a percentage of ventricular tissue in perfused hearts subjected to ischemia-reperfusion as in B. (F) Phosphorylation of AMPK and downstream ACC, detected on immunoblots of homogenates from perfused mouse hearts treated with anti-DDT or nonimmune IgG prior to 15 minutes of ischemia. Data are mean ± SEM, n = 4–6 per group. *P < 0.05 vs. respective control or as indicated by brackets.