In contrast to in vitro studies, AKIP1 overexpression does not influence cardiac remodelling in response to chronic cardiac stress. AKIP1 does, however, reduce myocardial I/R injury through stabilization of the MPT pore. These findings suggest that AKIP1 deserves further investigation as a putative treatment target for cardioprotection from I/R injury during acute myocardial infarction.

Heart failure (HF) has become the cardiovascular epidemic of the century and now imposes an immense burden on health care systems. While our understanding of the pathophysiology of HF has increased dramatically, the translation of knowledge into clinical practice has been disappointing. Metabolic dysfunction in HF has been studied for eight decades, but these efforts have not resulted in effective therapies. This paucity in clinical translation probably results from the variable contribution of metabolic dysfunction to the underlying heart disease. A major unmet need in cardiac drug development is therefore the ability to identify a homogeneous subset of patients in whom HF is driven by a specific mechanism that can be targeted. Areas covered: The available literature was evaluated to describe maladaptive metabolic perturbations that occur in failing hearts and may cause metabolic inflexibility, oxidative stress and cardiac energy depletion. Furthermore, the potential utility of various biomarkers and molecular imaging techniques to detect and quantify specific metabolic dysfunctions in HF were compared. Finally, the authors propose ways to utilize these techniques to select patients for specific metabolic interventions. Expert commentary: Metabolic dysfunction is among the most promising therapeutic targets in HF. Meticulous patient-selection with molecular imaging techniques and specific biomarkers appears indispensable for the effective translation of decades of scientific knowledge into clinical therapeutics.

ATPase inhibitory factor-1 (IF1) preserves cellular ATP under conditions of respiratory collapse, yet the function of IF1 under normal respiring conditions is unresolved. We tested the hypothesis that IF1 promotes mitochondrial dysfunction and pathological cardiomyocyte hyper-trophy in the context of heart failure (HF). Methods and results: Cardiac expression of IF1 was increased in mice and in humans with HF, downstream of neurohumoral signaling pathways and in patterns that resembled the fetal-like gene program. Adenoviral expression of wild-type IF1 in primary cardiomyocytes resulted in pathological hypertrophy and metabolic remodeling as evi-denced by enhanced mitochondrial oxidative stress, reduced mitochondrial respiratory capacity, and the augmentation of extramitochondrial glycolysis. Similar perturbations were observed with an IF1 mutant incapable of binding to ATP synthase (E55A mutation), an indication that these ef-fects occurred independent of binding to ATP synthase. Instead, IF1 promoted mitochondrial fragmentation and compromised mitochondrial Ca2+ handling, which resulted in sarcoplasmic re-ticulum Ca2+ overloading. The effects of IF1 on Ca2+ handling were associated with the cytosolic activation of calcium–calmodulin kinase II (CaMKII) and inhibition of CaMKII or co-expression of catalytically dead CaMKIIδC was sufficient to prevent IF1 induced pathological hypertrophy. Conclusions: IF1 represents a novel member of the fetal-like gene program that contributes to mi-tochondrial dysfunction and pathological cardiac remodeling in HF. Furthermore, we present ev-idence for a novel, ATP-synthase-independent, role for IF1 in mitochondrial Ca2+ handling and mitochondrial-to-nuclear crosstalk involving CaMKII.