Prior exercise induces cardioprotection against ischemia-reperfusion injury: contr...
| Grant number: | 15/04462-4 |
| Support type: | Scholarships in Brazil - Master |
| Effective date (Start): | July 01, 2015 |
| Effective date (End): | June 30, 2017 |
| Field of knowledge: | Biological Sciences - Physiology |
| Cooperation agreement: | Coordination of Improvement of Higher Education Personnel (CAPES) |
| Principal Investigator: | Julio Cesar Batista Ferreira |
| Grantee: | Laís Santos Domingues |
| Home Institution: | Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo, SP, Brazil |
| Associated research grant: | 12/05765-2 - Contribution of aldehyde dehydrogenase 2 to heart failure development, AP.JP |
Abstract Ischemic diseases are the leading cause of mortality and morbidity worldwide. The process known as ischemia-reperfusion (I/R) causes irreparable damage to the affected tissues due to the wide variation in tissue oxygen tension. Reperfusion of the affected tissue, which had been temporarily maintained at hypoxia (low oxygen tension), results in abrupt oxygen supply (high oxygen tension) and consequent metabolic collapse, characterized by mitochondrial dysfunction associated with high production of free radicals. Thus, a better understanding of the intracellular signals involved in the establishment and propagation of damage induced by ischemia-reperfusion is essential to the development of new strategies that can be used in the prevention and treatment of myocardial infarction, stroke and renal ischemia. We recently demonstrated that cardioprotective stimuli are accompanied by increased translocation of protein kinase C isoform epsilon (PKCepsilon) to the mitochondria and subsequent phosphorylation-activation of mitochondrial aldehyde dehydrogenase enzyme 2 (ALDH2), which has an inverse correlation with myocardial injury. ALDH2 is a key enzyme in the protection against ischemic damage due to its capacity to oxidize aldehydes (i.e. acetaldehyde and 4-hydroxynonenal) produced during oxidative stress. Similar to ischemic preconditioning, exercise promotes increased myocardial tolerance to ischemia-reperfusion injury; however the cellular mechanisms involved in this process are still poorly understood. We propose to validate the intracellular PKCepsilon-ALDH2 axis as a possible exercise-mediated cardioprotective mechanism upon ischemia-reperfusion. We will initially evaluate whether exercise (7 consecutive days) modulates the activity of PKCepsilon and ALDH2 (transient vs. sustained) and mitochondrial metabolism in the heart of wild-type mice. Then we will evaluate the individual role of PKCepsilon and ALDH2, and the relationship of PKCepsilon-ALDH2 axis in the exercise-mediated cardioprotection. For that, wild-type and genetically modified (knockout mice and mice PKCepsilon ALDH2 knock-in) mice will be exercised and hearts will be explanted and submitted to the protocol of ischemia-reperfusion ex vivo (Langendorff). We will therefore analyze physiological and biochemical parameters such as cardiac damage (infarct area, JNK phosphorylation, LDH release in the perfusate), mitochondrial O2 consumption, release of mitochondrial H2O2, lipid peroxidation, Michaelis adduct formation, expression and activation of PKCepsilon, phosphorylation and activity of ALDH2. Our preliminary data show that seven days of physical exercise on treadmill promote reduction of infarct area in wild mice subjected to ischemia-reperfusion protocol (relative to non-exercised). Furthermore, this cardioprotection is accompanied by increased cardiac PKCepsilon levels as well as increased ALDH2 activity. (AU) | |