Although reactive oxygen species (ROS) act as crucial factors in the onset and progression of a wide array of diseases, they are also involved in numerous signalling pathways related to cell metabolism, growth and survival. ROS are produced at various cellular sites, and it is generally agreed that mitochondria generate the largest amount, especially those in cardiomyocytes. However, the identification of the most relevant sites within mitochondria, the interaction among the various sources, and the events responsible for the increase in ROS formation under pathological conditions are still highly debated, and far from being clarified. Here, we review the information linking the adaptor protein p66Shc with cardiac injury induced by ischaemia and reperfusion (I/ R), including the contribution of risk factors, such as metabolic syndrome and ageing. In response to several stimuli, p66Shc migrates into mitochondria where it catalyses electron transfer from cytochrome c to oxygen resulting in hydrogen peroxide formation. Deletion of p66Shc has been shown to reduce I/R injury as well as vascular abnormalities associated with diabetes and ageing. However, p66Shc-induced ROS formation is also involved in insulin signalling and might contribute to self-endogenous defenses against mild I/R injury. In addition to its role in physiological and pathological conditions, we discuss compounds and conditions that can modulate the expression and activity of p66Shc.
LINKED ARTICLESThis article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc Abbreviations ATG, DNA codon for methionine; CAD, coronary artery disease; CH, collagen homologues; Δψ m , mitochondrial membrane potential; ETC, electron transport chain; GSH/GSSG, GSH in its reduced or oxidized form; IGF-1, insulin-like growth factor 1; PTP, permeability transition pore; PBM, peripheral blood monocyte; Ras, rat sarcoma; SH2, sarcoma homologous type 2; Sirtuin, silent mating type information regulation 2 homolog
Cardiac injury induced by ischaemia and reperfusionThe maintenance of cardiac structure and function depends on the continuous supply of ATP resulting from the mitochondrial coupling of substrate oxidation with ATP synthesis, termed as oxidative phosphorylation. The strict dependence of the heart on aerobic metabolism is indicated by the large fraction (i.e. >30%) of cardiomyocyte volume occupied by mitochondria. Therefore, it is hardly surprising that mitochondrial dysfunction and cardiac diseases are inevitably associated. This concept is perfectly exemplified by cardiac injury induced by ischaemia and reperfusion. Because more than 95% of oxygen is utilized by the terminal reaction of the respiratory chain, namely, cytochrome oxidase, anoxia or ischaemia is established when oxygen availability is no longer sufficient for the activity of cytochrome oxidase. Therefore, within any cell, ischaemic injury is determined...