Loss of miR-132/212 Has No Long-Term Beneficial Effect on Cardiac Function After Permanent Coronary Occlusion in Mice

Non-coding RNAs and angiogenesis in cardiovascular diseases: a comprehensive review

Non-coding RNAs (ncRNAs) have key roles in the etiology of many illnesses, including heart failure, myocardial infarction, stroke, and in physiological processes like angiogenesis. In transcriptional regulatory circuits that control heart growth, signaling, and stress response, as well as remodeling in cardiac disease, ncRNAs have become important players. Studies on ncRNAs and cardiovascular disease have made great progress recently. Here, we go through the functions of non-coding RNAs (ncRNAs) like circular RNAs (circRNAs), and microRNAs (miRNAs) as well as long non-coding RNAs (lncRNAs) in modulating cardiovascular disorders.

Beneficial effects of miR-132/212 deficiency in the zQ175 mouse model of Huntington's disease

Huntington's disease (HD) is a rare genetic neurodegenerative disorder caused by an expansion of CAG repeats in the Huntingtin (HTT) gene. One hypothesis suggests that the mutant HTT gene contributes to HD neuropathology through transcriptional dysregulation involving microRNAs (miRNAs). In particular, the miR-132/212 cluster is strongly diminished in the HD brain. This study explores the effects of miR-132/212 deficiency specifically in adult HD zQ175 mice. The absence of miR-132/212 did not impact body weight, body temperature, or survival rates. Surprisingly, miR-132/212 loss seemed to alleviate, in part, the effects on endogenous Htt expression, HTT inclusions, and neuronal integrity in HD zQ175 mice. Additionally, miR-132/212 depletion led to age-dependent improvements in certain motor functions. Transcriptomic analysis revealed alterations in HD-related networks in WT- and HD zQ175-miR-132/212-deficient mice, including significant overlap in BDNF and Creb1 signaling pathways. Interestingly, however, a higher number of miR-132/212 gene targets was observed in HD zQ175 mice lacking the miR-132/212 cluster, especially in the striatum. These findings suggest a nuanced interplay between miR-132/212 expression and HD pathogenesis, providing potential insights into therapeutic interventions. Further investigation is needed to fully understand the underlying mechanisms and therapeutic potential of modulating miR-132/212 expression during HD progression.

Delivery of modified mRNA to damaged myocardium by systemic administration of lipid nanoparticles

Lipid Nanoparticles (LNPs) are a promising drug delivery vehicle for clinical siRNA delivery. Modified mRNA (modRNA) has recently gained great attention as a therapeutic molecule in cardiac regeneration. However, for mRNA to be functional, it must first reach the diseased myocardium, enter the target cell, escape from the endosomal compartment into the cytosol and be translated into a functional protein. However, it is unknown if LNPs can effectively deliver mRNA, which is much larger than siRNA, to the ischemic myocardium. Here, we evaluated the ability of LNPs to deliver mRNA to the myocardium upon ischemia-reperfusion injury functionally. By exploring the bio-distribution of fluorescently labeled LNPs, we observed that, upon reperfusion, LNPs accumulated in the infarct area of the heart. Subsequently, the functional delivery of modRNA was evaluated by the administration of firefly luciferase encoding modRNA. Concomitantly, a significant increase in firefly luciferase expression was observed in the heart upon myocardial reperfusion when compared to sham-operated animals. To characterize the targeted cells within the myocardium, we injected LNPs loaded with Cre modRNA into Cre-reporter mice. Upon LNP infusion, Tdtomato+ cells, derived from Cre mediated recombination, were observed in the infarct region as well as the epicardial layer upon LNP infusion. Within the infarct area, most targeted cells were cardiac fibroblasts but also some cardiomyocytes and macrophages were found. Although the expression levels were low compared to LNP-modRNA delivery into the liver, our data show the ability of LNPs to functionally deliver modRNA therapeutics to the damaged myocardium, which holds great promise for modRNA-based cardiac therapies.

Advances in miR-132-Based Biomarker and Therapeutic Potential in the Cardiovascular System

Atherosclerotic cardiovascular disease and subsequent heart failure threaten global health and impose a huge economic burden on society. MicroRNA-132 (miR-132), a regulatory RNA ubiquitously expressed in the cardiovascular system, is up-or down-regulated in the plasma under various cardiac conditions and may serve as a potential diagnostic or prognostic biomarker. More importantly, miR-132 in the myocardium has been demonstrated to be a master regulator in many pathological processes of ischemic or nonischemic heart failure in the past decade, such as myocardial hypertrophy, fibrosis, apoptosis, angiogenesis, calcium handling, neuroendocrine activation, and oxidative stress, through downregulating target mRNA expression. Preclinical and clinical phase 1b studies have suggested antisense oligonucleotide targeting miR-132 may be a potential therapeutic approach for ischemic or nonischemic heart failure in the future. This review aims to summarize recent advances in the physiological and pathological functions of miR-132 and its possible diagnostic and therapeutic potential in cardiovascular disease.

miR-132/212 Impairs Cardiomyocytes Contractility in the Failing Heart by Suppressing SERCA2a

Compromised cardiac function is a hallmark for heart failure, mostly appearing as decreased contractile capacity due to dysregulated calcium handling. Unfortunately, the underlying mechanism causing impaired calcium handling is still not fully understood. Previously the miR-132/212 family was identified as a regulator of cardiac function in the failing mouse heart, and pharmaceutically inhibition of miR-132 is beneficial for heart failure. In this study, we further investigated the molecular mechanisms of miR-132/212 in modulating cardiomyocyte contractility in the context of the pathological progression of heart failure. We found that upregulated miR-132/212 expressions in all examined hypertrophic heart failure mice models. The overexpression of miR-132/212 prolongs calcium decay in isolated neonatal rat cardiomyocytes, whereas cardiomyocytes isolated from miR-132/212 KO mice display enhanced contractility in comparison to wild type controls. In response to chronic pressure-overload, miR-132/212 KO mice exhibited a blunted deterioration of cardiac function. Using a combination of biochemical approaches and in vitro assays, we confirmed that miR-132/212 regulates SERCA2a by targeting the 3′-end untranslated region of SERCA2a. Additionally, we also confirmed PTEN as a direct target of miR-132/212 and potentially participates in the cardiac response to miR132/212. In end-stage heart failure patients, miR-132/212 is upregulated and correlates with reduced SERCA2a expression. The up-regulation of miR-132/212 in heart failure impairs cardiac contractile function by targeting SERCA2a, suggesting that pharmaceutical inhibition of miR-132/212 might be a promising therapeutic approach to promote cardiac function in heart failure patients.