Novel therapies for myocardial infarct: the role of physical training and novel circular RNAs

Abstract

Aerobic exercise training (AET) is known by the capacity to attenuate the deleterious effects of the myocardial infarction (MI) and heart failure as well as to increase the heart disease patient's survival. In this sense, many mechanisms are demonstrated to participate in this process, however, there is a lack in the literature on the participation of circular RNAs (circRNA) in these responses. Competitive endogenous RNAs (ceRNAs) are natural transcripts that act as microRNAs sponges endogenous, modulating the action of microRNAs on theirs mRNAs-target. CircRNA is one among several classes of ceRNA. CircRNAs are formed by process called backsplicing, which is the formation of a covalently closed continuous loop. Many circRNAs control the stability and activity of microRNAs, regulating gene transcription or alternative splicing, modifying the translation of host genes, or even they can even be translated and produce proteins1. They are expressed in various cell types, and have a great ability to regulate gene expression, mainly binding and inhibiting microRNAs expression, working as microRNAs' sponges. We have demonstrated that AET attenuates the cardiac dysfunction in infarcted rats regulated by microRNAs2,3. However, with AET, there are no data in the literature showing the role of circRNAs acting as microRNAs' sponge modulating their action on mRNAs-targets, although several studies show their crucial role in cardiac development and physiology4. Abnormal expression of circRNAs has been associated with cardiovascular diseases such as heart failure, myocardial infarction and atherosclerosis, indicating the potential importance of the circRNAs in these pathological conditions. However, it is still unknown if AET modulates decompensated circRNAs in myocardial infarction, promoting attenuation of disease progression, preventing heart failure. Considering the results of our laboratory and the above, we will investigate the role of AET in modulating circRNAs by attenuating myocardial infarction in Wistar rats. Specifically, by the high-throughput RNA sequencing (mRNA, circRNA and microRNA sequencing) a regulatory network will be drawn of the circRNAs-microRNAs-mRNA expressed in the heart of sedentary (SED), trained (TR), infarcted (I) and infarcted trained (ITR) animals will be analyzed. After, those circRNAs modulated in the IM and that are altered by the AET (ITR) will be identified, in particular looking for those that are normalized to the expression pattern of the SED or TR groups. By a strong bioinformatics analysis, the microRNAs-target of the circRNAs, genes and signaling pathways involved will be identified. For in vitro study (cardiomyocytes culture treated with Isoproterenol) and in vivo (infarcted Wistar rats) will be selected 1 or 2 circRNAs modulated by AET will be selected for validation of their beneficial effects in pathological conditions. Thus, viral vectors with rAAV9-MHC- circRNA sequence will be constructed to increase the expression of the circRNA selected or inhibited with RNAi to analyze whether they prevent cardiac dysfunction and morphology in cardiomyocytes. To the translational application, bioinformatics analyzes will investigate if the circRNAs found are associated with lifespan in different cohorts of patients with myocardial infarction. (AU)