Complexome profiling identifies changes in mitochondrial supercomplexes in murine heart failure

Heart failure is characterized by metabolic derangements such as altered substrate metabolism and mitochondrial dysfunction. Mitochondrial supercomplexes, which are higher-order molecular structures comprised of multisubunit complexes of the electron transport chain, are decreased in heart failure. To investigate the supercomplex proteome composition in heart failure, we used an in vivo myocardial infarction (MI) model in which mice exhibited reduced cardiac function, confirmed by two-dimensional echocardiography at 4 wk postinfarction. To assess proteins within supercomplexes, we used an emerging technique known as complexome profiling. This technique involved separating out mitochondrial protein complexes using Blue-Native PAGE combined with mass spectrometry to identify proteins within supercomplex gel bands. We identified band-dependent decreases or increases in the relative abundance of subunits of the electron transport chain between MI and sham mice. Decreased abundance of proteins involved in α-ketoglutarate dehydrogenase metabolism, including dihydrolipoamide S-succinyltransferase (DLST), was also identified in the supercomplex bands of MI mice compared with sham mice. In addition, decreased abundance of redox-related proteins such as superoxide dismutase 2 (SOD2) and changes in ribosome protein subunits were identified in the MI mitochondria. In conclusion, we identified changes in the mitochondrial supercomplex proteome in a murine model of heart failure, providing insight and novel mechanisms that may be contributing to the metabolic dysfunction in heart failure.<b>NEW & NOTEWORTHY</b> This study identified novel changes in the proteome of mitochondrial supercomplexes in a murine model of heart failure, including alterations in the relative abundance of metabolic protein complexes, redox proteins, and ribosomal proteins. These findings provide new insights into potential mechanisms that may contribute to metabolic dysfunction in heart failure.