Defective Branched-Chain Amino Acid Catabolism Disrupts Glucose Metabolism and Sensitizes the Heart to Ischemia-Reperfusion Injury

Publication date: 7 February 2017
Source:Cell Metabolism, Volume 25, Issue 2
Author(s): Tao Li, Zhen Zhang, Stephen C. Kolwicz, Lauren Abell, Nathan D. Roe, Maengjo Kim, Bo Zhou, Yang Cao, Julia Ritterhoff, Haiwei Gu, Daniel Raftery, Haipeng Sun, Rong Tian
Elevated levels of branched-chain amino acids (BCAAs) have recently been implicated in the development of cardiovascular and metabolic diseases, but the molecular mechanisms are unknown. In a mouse model of impaired BCAA catabolism (knockout [KO]), we found that chronic accumulation of BCAAs suppressed glucose metabolism and sensitized the heart to ischemic injury. High levels of BCAAs selectively disrupted mitochondrial pyruvate utilization through inhibition of pyruvate dehydrogenase complex (PDH) activity. Furthermore, downregulation of the hexosamine biosynthetic pathway in KO hearts decreased protein O-linked N-acetylglucosamine (O-GlcNAc) modification and inactivated PDH, resulting in significant decreases in glucose oxidation. Although the metabolic remodeling in KO did not affect baseline cardiac energetics or function, it rendered the heart vulnerable to ischemia-reperfusion injury. Promoting BCAA catabolism or normalizing glucose utilization by overexpressing GLUT1 in the KO heart rescued the metabolic and functional outcome. These observations revealed a novel role of BCAA catabolism in regulating cardiac metabolism and stress response.

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Teaser

Branched-chain amino acids (BCAAs) have been implicated in cardiovascular disease. Li et al. now reveal molecular mechanisms behind BCAA catabolism in regulating cardiac metabolism and stress response. Chronic accumulation of BCAAs downregulates the hexosamine biosynthetic pathway and inactivates pyruvate dehydrogenase, which renders the heart vulnerable to ischemic injury.


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