Hsp90aa1: a novel target gene of miR-1 in cardiac ischemia/reperfusion injury

Preconditioning with acteoside ameliorates myocardial ischemia‑reperfusion injury by targeting HSP90AA1 and the PI3K/Akt signaling pathway

The present study aimed to investigate the cardioprotective effects of acteoside (AC) on myocardial ischemia‑reperfusion injury (MIRI). To meet this aim, a network pharmacological analysis was conducted to search for key genes and signaling pathways associated with AC and MIRI. The infarct size of the rat heart was evaluated using 2,3,5‑triphenyltetrazolium chloride staining, and the serum levels of creatine kinase MB isoenzyme, cardiac troponin I, malondialdehyde and superoxide dismutase were subsequently detected in an in vivo experiment. The inhibitory effect of AC on oxidative stress was further confirmed by assessing the intracellular accumulation of reactive oxygen species (ROS). Hematoxylin and eosin staining was subsequently carried out to observe cardiac histopathological damage. The anti‑apoptotic effects of AC were determined using terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labeling assay and Hoechst 33342 staining, and the expression levels of apoptosis‑associated proteins in the myocardial tissue were assessed using immunohistochemical analysis. In addition, cell viability was determined using a Cell Counting Kit‑8 assay, and the expression levels of key target proteins associated with AC and MIRI were detected by western blot analysis. The results suggested that pretreatment with AC could mitigate MIRI‑induced myocardial damage, oxidative stress and apoptosis. The anti‑apoptotic effects of AC were associated with elevated Bcl‑2 levels, and reduced caspase‑3 and Bax expression levels in myocardial tissue. In vitro, AC pretreatment both led to an increased rate of cell survival and alleviated oxidative stress, as demonstrated by a decreased level of intracellular ROS accumulation. Moreover, guided by the network pharmacological analysis, heat‑shock protein 90AA1 (HSP90AA1) and the phosphoinositide 3‑kinase (PI3K)/serine‑threonine protein kinase (Akt) signaling pathway emerged as key targets for the action of AC against MIRI. Furthermore, the western blot analysis results showed that pretreatment with AC led to a significant increase in the activity of the PI3K/Akt signaling pathway, in addition to increased expression levels of glycogen synthase kinase‑3β and HSP90AA1. Taken together, the findings of the present study revealed that AC may exert cardioprotective effects on MIRI through suppressing apoptosis and oxidative stress by regulating the expression and activity of key proteins.

LncRNA RNA ROR Aggravates Hypoxia/Reoxygenation-Induced Cardiomyocyte Ferroptosis by Targeting miR-769-5p/CBX7 Axis

Ferroptosis is a new way of cell death which is reported to participate in the pathology of myocardial ischemia-reperfusion (MI/R) injury, but it's mechanism remains unclear. The present investigation is to study the emerging role of long non-coding RNA (lncRNA) regulator of reprogramming (ROR) in cardiomyocyte ferroptosis after hypoxia/reoxygenation (H/R) administration. RT-qPCR and/or Western blot methods were performed to examine the gene/or protein levels, and CCK-8, ELISA, and DCFH-DA staining determined the cellular viability and ferroptosis. Dual-luciferase and RNA immunoprecipitation were applied to verify molecular interaction. LncRNA ROR and miR-769-5p were overexpressed and reduced in blood samples from MI patients and H/R-treated AC16 cells, respectively. Mechanistically, lncROR sponged to miR-769-5p, thus upregulating CBX7 expression. Functional experiments presented that lncRNA ROR silence mitigated H/R-stimulated inflammatory damage, oxidative stress, and ferroptosis in AC16 cells, whereas these roles could be reversed by co-downregulation of miR-769-5p or co-overexpression of CBX7. These data uncovered that lncRNA ROR prevented against H/R-induced cardiomyocyte ferroptosis by modulating miR-769-5p/CBX7 signaling, emphasizing the therapeutic value of lncRNA ROR in MI/R injury.

Bioinformatics integration reveals key genes associated with mitophagy in myocardial ischemia-reperfusion injury

BACKGROUND

Myocardial ischemia is a prevalent cardiovascular disorder associated with significant morbidity and mortality. While prompt restoration of blood flow is essential for improving patient outcomes, the subsequent reperfusion process can result in myocardial ischemia-reperfusion injury (MIRI). Mitophagy, a specialized autophagic mechanism, has consistently been implicated in various cardiovascular disorders. However, the specific connection between ischemia-reperfusion and mitophagy remains elusive. This study aims to elucidate and validate central mitophagy-related genes associated with MIRI through comprehensive bioinformatics analysis.

METHODS

We acquired the microarray expression profile dataset (GSE108940) from the Gene Expression Omnibus (GEO) and identified differentially expressed genes (DEGs) using GEO2R. Subsequently, these DEGs were cross-referenced with the mitophagy database, and differential nucleotide sequence analysis was performed through enrichment analysis. Protein-protein interaction (PPI) network analysis was employed to identify hub genes, followed by clustering of these hub genes using cytoHubba and MCODE within Cytoscape software. Gene set enrichment analysis (GSEA) was conducted on central genes. Additionally, Western blotting, immunofluorescence, and quantitative polymerase chain reaction (qPCR) analyses were conducted to validate the expression patterns of pivotal genes in MIRI rat model and H9C2 cardiomyocytes.

RESULTS

A total of 2719 DEGs and 61 mitophagy-DEGs were identified, followed by enrichment analyses and the construction of a PPI network. HSP90AA1, RPS27A, EEF2, EIF4A1, EIF2S1, HIF-1α, and BNIP3 emerged as the seven hub genes identified by cytoHubba and MCODE of Cytoscape software. Functional clustering analysis of HIF-1α and BNIP3 yielded a score of 9.647, as determined by Cytoscape (MCODE). In our MIRI rat model, Western blot and immunofluorescence analyses confirmed a significant elevation in the expression of HIF-1α and BNIP3, accompanied by a notable increase in the ratio of LC3II to LC3I. Subsequently, qPCR confirmed a significant upregulation of HIF-1α, BNIP3, and LC3 mRNA in the MIRI group. Activation of the HIF-1α/BNIP3 pathway mediates the regulation of the degree of Mitophagy, thereby effectively reducing apoptosis in rat H9C2 cardiomyocytes.

CONCLUSIONS

This study has identified seven central genes among mitophagy-related DEGs that may play a pivotal role in MIRI, suggesting a correlation between the HIF-1α/BNIP3 pathway of mitophagy and the pathogenesis of MIRI. The findings highlight the potential importance of mitophagy in MIRI and provide valuable insights into underlying mechanisms and potential therapeutic targets for further exploration in future studies.

Bioinformatics-based identification and validation of hub genes associated with aging in patients with coronary artery disease

Coronary artery disease (CAD) is the most common aging-related disease in adults. We used bioinformatics analysis to study genes associated with aging in patients with CAD. The microarray data of the GSE12288 dataset were downloaded from the Gene Expression Omnibus database to obtain 934 CAD-associated differentially expressed genes. By overlaying them with aging-related genes in the Aging Atlas database, 33 differentially expressed aging-related genes (DEARGs) were identified. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that the 33 DEARGs were mainly enriched in cell adhesion and activation, Th17 and Th1/Th2 cell differentiation, and longevity regulation pathways. Hub genes were further screened using multiple algorithms of Cytoscape software and validation set GSE71226. Clinical samples were then collected, and the expression of hub genes in whole blood was detected by real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, and western blot at the transcription and translation levels. Finally, HSP90AA1 and CEBPA were identified as hub genes. The results of this study suggest that HSP90AA1 and CEBPA are closely related to CAD. These findings provide a theoretical basis for the association between aging effectors and CAD, and indicate that these genes may be promising biomarkers for the diagnosis and treatment of CAD.

HSP90 and Noncoding RNAs

Heat shock protein 90 (HSP90) family is a class of proteins known as molecular chaperones that promote client protein folding and translocation in unstressed cells and regulate cellular homeostasis in the stress response. Noncoding RNAs (ncRNAs) are defined as RNAs that do not encode proteins. Previous studies have shown that ncRNAs are key regulators of multiple fundamental cellular processes, such as development, differentiation, proliferation, transcription, post-transcriptional modifications, apoptosis, and cell metabolism. It is known that ncRNAs do not act alone but function via the interactions with other molecules, including co-chaperones, RNAs, DNAs, and so on. As a kind of molecular chaperone, HSP90 is also involved in many biological procedures of ncRNAs. In this review, we systematically analyze the impact of HSP90 on various kinds of ncRNAs, including their synthesis and function, and how ncRNAs influence HSP90 directly and indirectly.

A bibliometric analysis of myocardial ischemia/reperfusion injury from 2000 to 2023

Background

Myocardial ischemia/reperfusion injury (MIRI) refers to the more severe damage that occurs in the previously ischemic myocardium after a short-term interruption of myocardial blood supply followed by restoration of blood flow within a certain period of time. MIRI has become a major challenge affecting the therapeutic efficacy of cardiovascular surgery.

Methods

A scientific literature search on MIRI-related papers published from 2000 to 2023 in the Web of Science Core Collection database was conducted. VOSviewer was used for bibliometric analysis to understand the scientific development and research hotspots in this field.

Results

A total of 5,595 papers from 81 countries/regions, 3,840 research institutions, and 26,202 authors were included. China published the most papers, but the United States had the most significant influence. Harvard University was the leading research institution, and influential authors included Lefer David J., Hausenloy Derek J., Yellon Derek M., and others. All keywords can be divided into four different directions: risk factors, poor prognosis, mechanisms and cardioprotection.

Conclusion

Research on MIRI is flourishing. It is necessary to conduct an in-depth investigation of the interaction between different mechanisms and multi-target therapy will be the focus and hotspot of MIRI research in the future.

Identification of biomarkers, pathways, and potential therapeutic targets for heart failure using next-generation sequencing data and bioinformatics analysis

BACKGROUND

Heart failure (HF) is the most common cardiovascular diseases and the leading cause of cardiovascular diseases related deaths. Increasing molecular targets have been discovered for HF prognosis and therapy. However, there is still an urgent need to identify novel biomarkers. Therefore, we evaluated biomarkers that might aid the diagnosis and treatment of HF.

METHODS

We searched next-generation sequencing (NGS) dataset (GSE161472) and identified differentially expressed genes (DEGs) by comparing 47 HF samples and 37 normal control samples using limma in R package. Gene ontology (GO) and pathway enrichment analyses of the DEGs were performed using the g: Profiler database. The protein-protein interaction (PPI) network was plotted with Human Integrated Protein-Protein Interaction rEference (HiPPIE) and visualized using Cytoscape. Module analysis of the PPI network was done using PEWCC1. Then, miRNA-hub gene regulatory network and TF-hub gene regulatory network were constructed by Cytoscape software. Finally, we performed receiver operating characteristic (ROC) curve analysis to predict the diagnostic effectiveness of the hub genes.

RESULTS

A total of 930 DEGs, 464 upregulated genes and 466 downregulated genes, were identified in HF. GO and REACTOME pathway enrichment results showed that DEGs mainly enriched in localization, small molecule metabolic process, SARS-CoV infections, and the citric acid tricarboxylic acid (TCA) cycle and respiratory electron transport. After combining the results of the PPI network miRNA-hub gene regulatory network and TF-hub gene regulatory network, 10 hub genes were selected, including heat shock protein 90 alpha family class A member 1 (HSP90AA1), arrestin beta 2 (ARRB2), myosin heavy chain 9 (MYH9), heat shock protein 90 alpha family class B member 1 (HSP90AB1), filamin A (FLNA), epidermal growth factor receptor (EGFR), phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1), cullin 4A (CUL4A), YEATS domain containing 4 (YEATS4), and lysine acetyltransferase 2B (KAT2B).

CONCLUSIONS

This discovery-driven study might be useful to provide a novel insight into the diagnosis and treatment of HF. However, more experiments are needed in the future to investigate the functional roles of these genes in HF.

Epigenetics and Gut Microbiota Crosstalk: A potential Factor in Pathogenesis of Cardiovascular Disorders

Cardiovascular diseases (CVD) are the leading cause of mortality, morbidity, and "sudden death" globally. Environmental and lifestyle factors play important roles in CVD susceptibility, but the link between environmental factors and genetics is not fully established. Epigenetic influence during CVDs is becoming more evident as its direct involvement has been reported. The discovery of epigenetic mechanisms, such as DNA methylation and histone modification, suggested that external factors could alter gene expression to modulate human health. These external factors also influence our gut microbiota (GM), which participates in multiple metabolic processes in our body. Evidence suggests a high association of GM with CVDs. Although the exact mechanism remains unclear, the influence of GM over the epigenetic mechanisms could be one potential pathway in CVD etiology. Both epigenetics and GM are dynamic processes and vary with age and environment. Changes in the composition of GM have been found to underlie the pathogenesis of metabolic diseases via modulating epigenetic changes in the form of DNA methylation, histone modifications, and regulation of non-coding RNAs. Several metabolites produced by the GM, including short-chain fatty acids, folates, biotin, and trimethylamine-N-oxide, have the potential to regulate epigenetics, apart from playing a vital role in normal physiological processes. The role of GM and epigenetics in CVDs are promising areas of research, and important insights in the field of early diagnosis and therapeutic approaches might appear soon.

Senolytic treatment preserves biliary regenerative capacity lost through cellular senescence during cold storage

Liver transplantation is the only curative option for patients with end-stage liver disease. Despite improvements in surgical techniques, nonanastomotic strictures (characterized by the progressive loss of biliary tract architecture) continue to occur after liver transplantation, negatively affecting liver function and frequently leading to graft loss and retransplantation. To study the biological effects of organ preservation before liver transplantation, we generated murine models that recapitulate liver procurement and static cold storage. In these models, we explored the response of cholangiocytes and hepatocytes to cold storage, focusing on responses that affect liver regeneration, including DNA damage, apoptosis, and cellular senescence. We show that biliary senescence was induced during organ retrieval and exacerbated during static cold storage, resulting in impaired biliary regeneration. We identified decoy receptor 2 (DCR2)-dependent responses in cholangiocytes and hepatocytes, which differentially affected the outcome of those populations during cold storage. Moreover, CRISPR-mediated DCR2 knockdown in vitro increased cholangiocyte proliferation and decreased cellular senescence but had the opposite effect in hepatocytes. Using the p21KO model to inhibit senescence onset, we showed that biliary tract architecture was better preserved during cold storage. Similar results were achieved by administering senolytic ABT737 to mice before procurement. Last, we perfused senolytics into discarded human donor livers and showed that biliary architecture and regenerative capacities were better preserved. Our results indicate that cholangiocytes are susceptible to senescence and identify the use of senolytics and the combination of senotherapies and machine-perfusion preservation to prevent this phenotype and reduce the incidence of biliary injury after transplantation.

Ischemic Postconditioning Protects against Aged Myocardial Ischemia/Reperfusion Injury by Transcriptional and Epigenetic Regulation of miR-181a-2-3p

Ischemic postconditioning (IPostC) has been proposed as a strategy to mitigate the risk of ischemia/reperfusion (I/R) injury, and autophagy is involved in I/R-induced aged myocardial injury, while the underlying mechanism of IPostC-regulated autophagy is unknown. Here, we implemented miRNA sequencing analysis in aged cardiomyocytes to identify a novel miR-181a-2-3p after HPostC, which inhibits autophagy by targeting AMBRA1 in aged myocardium to protect I/R-induced aged myocardial injury. Mechanistically, we identified that IPostC can induce DNA hypomethylation and H3K14 hyperacetylation of miR-181a-2-3p promoter due to the decreased binding of DNMT3b and HDAC2 at its promoter, which contributes to enhancing the expression of miR-181a-2-3p. More importantly, cooperation of DNMT3b and HDAC2 inhibits the binding of c-Myc at the miR-181a-2-3p promoter in aged cardiomyocytes. In summary, IPostC attenuates I/R-induced aged myocardial injury through upregulating miR-181a-2-3p expression, which is an attribute to transcriptional and epigenetic regulation of its promoter. Our data indicate that miR-181a-2-3p may be a potential therapeutic target against I/R injury in aged myocardium.

Identification of candidate biomarkers and pathways associated with type 1 diabetes mellitus using bioinformatics analysis

Type 1 diabetes mellitus (T1DM) is a metabolic disorder for which the underlying molecular mechanisms remain largely unclear. This investigation aimed to elucidate essential candidate genes and pathways in T1DM by integrated bioinformatics analysis. In this study, differentially expressed genes (DEGs) were analyzed using DESeq2 of R package from GSE162689 of the Gene Expression Omnibus (GEO). Gene ontology (GO) enrichment analysis, REACTOME pathway enrichment analysis, and construction and analysis of protein–protein interaction (PPI) network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network, and validation of hub genes were performed. A total of 952 DEGs (477 up regulated and 475 down regulated genes) were identified in T1DM. GO and REACTOME enrichment result results showed that DEGs mainly enriched in multicellular organism development, detection of stimulus, diseases of signal transduction by growth factor receptors and second messengers, and olfactory signaling pathway. The top hub genes such as MYC, EGFR, LNX1, YBX1, HSP90AA1, ESR1, FN1, TK1, ANLN and SMAD9 were screened out as the critical genes among the DEGs from the PPI network, modules, miRNA-hub gene regulatory network and TF-hub gene regulatory network. Receiver operating characteristic curve (ROC) analysis confirmed that these genes were significantly associated with T1DM. In conclusion, the identified DEGs, particularly the hub genes, strengthen the understanding of the advancement and progression of T1DM, and certain genes might be used as candidate target molecules to diagnose, monitor and treat T1DM.

Multiomics Data Integration Identifies New Molecular Signatures for Abdominal Aortic Aneurysm and Aortic Occlusive Disease: Implications for Early Diagnosis, Prognosis, and Therapeutic Targets

Cardiovascular disease (CVD) is the leading cause of death among adults in developed countries. Among CVDs, abdominal aortic aneurysm (AAA) and aortic occlusive disease (AOD) are of great public health importance because of the high mortality rate in the elderly population. Despite significant molecular insights into AAA and AOD, the molecular mechanisms of these diseases remain unclear, and the current lack of robust diagnostic and prognostic biomarkers requires novel approaches to biomarker discovery and molecular targeting. In this study, we performed a comparative analysis of genome-wide expression data from patients with large AAA (n = 29), small AAA (n = 20), AOD (n = 9), and controls (n = 10). Specifically, we identified the differentially expressed genes and associated molecular pathways and biological processes (BPs) in each disease. Using a systems science approach, these data were linked to comprehensive human biological networks (i.e., protein-protein interaction, transcriptional regulatory, and metabolic networks) to identify molecular signatures of the salient mechanisms of AAA and AOD. Significant alterations in lipid metabolism and valine, leucine, and isoleucine metabolism, as well as neurodegenerative diseases and sex differences in the pathogenesis of AAA and AOD were identified. In the presence of aneurysm, size-dependent changes in lipid metabolism were observed. In addition, molecules and signaling pathways related to immunity, inflammation, infectious disease, and oxidative phosphorylation were identified in common. The results of the comparative and integrative analyzes revealed important clues to disease mechanisms and reporter molecules at various levels that warrant future development as potential prognostic biomarkers and putative therapeutic targets.

An Integrated Approach Based on Network Analysis Combined With Experimental Verification Reveals PI3K/Akt/Nrf2 Signaling Is an Important Way for the Anti-Myocardial Ischemia Activity of Yi-Qi-Tong-Luo Capsule

Background: Yiqi-Tongluo Capsule (YTC) is a Chinese traditional patent medicine that has been used in the treatment of myocardial ischemia (MI). However, its molecular mechanisms against MI have not been clear. Methods: Network analysis and experimental verification were used to explore the potential molecular mechanisms of YTC for MI treatment. Firstly, the main components in the capsules and the potential targets of these components were predicted by online databases. The MI related genes were collected from Genecards and Online Mendelian Inheritance in Man (OMIM) databases. The drug targets and disease targets were intersected, and then the protein-protein interaction (PPI) and Drug-Molecular-Target-Disease Network (DMTD) were constructed, and GO enrichment analysis and KEGG pathway enrichment analysis were performed. Based on the H₂O₂-stimulated H9c2 cells, flow cytometry, western blot (WB) and immunofluorescence experiments were performed to verify the network analysis prediction. Results: A total of 100 active components and 165 targets of YTC were predicted, in which there were 109 targets intersected with the targets of MI. GO and KEGG analysis showed that these potential targets were related to a variety of biological processes and molecular mechanisms, including oxidative stress and PI3K/AKT pathway. Astragaloside IV (AS IV) and paeoniflorin (PAE) might be the main active components in YTC. The results of cell counting kit-8 (CCK-8) showed that YTC alleviated the damage of H₂O₂ to H9c2 cells. The results of flow cytometry, DAPI staining and JC-1 probe showed that YTC alleviated H₂O₂ induced apoptosis in H9c2 cells. In addition, YTC reduced the level of intracellular superoxide anion, increased the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), and reduced the content of malondialdehyde (MDA) in H₂O₂-induced H9c2 cells. The results of immunofluorescence and WB showed that the phosphorylation of PI3K and Akt were increased, the expression of Bcl-2 was up-regulated and the expression of cleaved caspase-3 and Bax were down-regulated. Besides, the nuclear translocation of Nrf2 were increased. Conclusion: In conclusion, the results of this study showed that YTC might alleviate MI by suppressing apoptosis induced by oxidative stress via the PI3K/Akt/Nrf2 signal pathway.

Role of miRNA-1 and miRNA-21 in Acute Myocardial Ischemia-Reperfusion Injury and Their Potential as Therapeutic Strategy

Coronary artery disease remains the leading cause of death. Acute myocardial infarction (MI) is characterized by decreased blood flow to the coronary arteries, resulting in cardiomyocytes death. The most effective strategy for treating an MI is early and rapid myocardial reperfusion, but restoring blood flow to the ischemic myocardium can induce further damage, known as ischemia-reperfusion (IR) injury. Novel therapeutic strategies are critical to limit myocardial IR injury and improve patient outcomes following reperfusion intervention. miRNAs are small non-coding RNA molecules that have been implicated in attenuating IR injury pathology in pre-clinical rodent models. In this review, we discuss the role of miR-1 and miR-21 in regulating myocardial apoptosis in ischemia-reperfusion injury in the whole heart as well as in different cardiac cell types with special emphasis on cardiomyocytes, fibroblasts, and immune cells. We also examine therapeutic potential of miR-1 and miR-21 in preclinical studies. More research is necessary to understand the cell-specific molecular principles of miRNAs in cardioprotection and application to acute myocardial IR injury.

Uncovering the molecular mechanisms of Ilex pubescens against myocardial ischemia-reperfusion injury using network pharmacology analysis and experimental pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Ilex pubescens (I. pubescens), has been widely used to treat cardiovascular disease (CVD) in South China. Several studies have revealed aspect of its phytochemistry and pharmacological activities in cardiovascular diseases, but its active compounds and mechanisms of action are still unclear. The aim of this study was to search for the active compounds and the pharmacological mechanisms of I. pubescens for myocardial ischemia-reperfusion injury (MI/RI) by an integrative pharmacology-based investigation.

MATERIALS AND METHODS

The main targets of compounds in I. pubescens were predicted using the TargetNet webserver (http://targetnet.scbdd.com). The network between compounds and predicted targets related to MI/RI and compounds was constructed. Functional enrichment analysis was performed to investigate the specific functions and pathways involved in the candidate I. pubescens targets acting on MI/RI, which were further validated by in vitro and in vivo experiments.

RESULTS

A total of 191 targets were predicted for 64 chemical compounds in I. pubescens. Following Venn's analysis, we found that 38 candidate targets of I. pubescens were associated with protective effects against MI/RI. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that these targets were related to estrogen signaling pathway. Importantly, the cardioprotective effects of I. pubescens and its active compounds were evaluated and the regulatory effects on key targets of heat shock protein 90 alpha family class A member 1 (HSP90AA1) and Estrogen receptor 1 (ESRα) in estrogen signaling pathway were validated in vitro and in vivo.

CONCLUSION

Our discoveries revealed that I. pubescens ameliorated MI/RI by regulating HSP90AA1 and ESRα in estrogen signaling pathway.

Diagnostic and Prognostic Value of miRNAs after Coronary Artery Bypass Grafting: A Review

MiRNAs are noncoding, 21-24 nucleotide-long RNA particles that control over 60% of genes. MiRNAs affect gene expression through binding to the 3'-untranslated region of messenger RNA (mRNA), thus inhibiting mRNA translation or inducing mRNA degradation. MiRNAs have been associated with various cardiovascular diseases, including heart failure, hypertension, left ventricular hypertrophy, or ischemic heart disease. In addition, miRNA expression alters during coronary artery bypass grafting (CABG) surgery, which could be used to predict perioperative outcomes. CABG is an operation in which complex coronary arteries stenosis is treated by bypassing atherosclerotic lesions with venous or arterial grafts. Despite a very low perioperative mortality rate and excellent long-term survival, CABG is associated with postoperative complications, including reperfusion injury, graft failure, atrial fibrillation and perioperative myocardial infarction. So far, no reliable diagnostic and prognostic tools to predict prognosis after CABG have been developed. Changes in the perioperative miRNA expression levels could improve the diagnosis of post-CABG myocardial infarction and atrial fibrillation and could be used to stratify risk after CABG. Herein, we describe the expression changes of different subtypes of miRNAs during CABG and review the diagnostic and prognostic utility of miRNAs in patients undergoing CABG.

Sex-related differences of early cardiac functional and proteomic alterations in a rat model of myocardial ischemia

BACKGROUND

Reduced cardiovascular risk in premenopausal women has been the focus of research in recent decades. Previous hypothesis-driven experiments have highlighted the role of sex hormones on distinct inflammatory responses, mitochondrial proteins, extracellular remodeling and estrogen-mediated cardioprotective signaling pathways related to post-ischemic recovery, which were associated with better cardiac functional outcomes in females. We aimed to investigate the early, sex-specific functional and proteomic changes following myocardial ischemia in an unbiased approach.

METHODS

Ischemia was induced in male (M-Isch) and female (F-Isch) rats with sc. injection of isoproterenol (85 mg/kg) daily for 2 days, while controls (M-Co, F-Co) received sc. saline solution. At 48 h after the first injection pressure-volume analysis was carried out to assess left ventricular function. FFPE tissue slides were scanned and analyzed digitally, while myocardial proteins were quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using isobaric labeling. Concentrations of circulating steroid hormones were measured with LC-MS/MS. Feature selection (PLS and PLS-DA) was used to examine associations among functional, proteomic and hormonal datasets.

RESULTS

Induction of ischemia resulted in 38% vs 17% mortality in M-Isch and F-Isch respectively. The extent of ischemic damage to surviving rats was comparable between the sexes. Systolic dysfunction was more pronounced in males, while females developed a more severe impairment of diastolic function. 2224 proteins were quantified, with 520 showing sex-specific differential regulation. Our analysis identified transcriptional, cytoskeletal, contractile, and mitochondrial proteins, molecular chaperones and the extracellular matrix as sources of disparity between the sexes. Bioinformatics highlighted possible associations of estrogens and their metabolites with early functional and proteomic alterations.

CONCLUSIONS

Our study has highlighted sex-specific alterations in systolic and diastolic function shortly after ischemia, and provided a comprehensive look at the underlying proteomic changes and the influence of estrogens and their metabolites. According to our bioinformatic analysis, inflammatory, mitochondrial, chaperone, cytoskeletal, extracellular and matricellular proteins are major sources of intersex disparity, and may be promising targets for early sex-specific pharmacologic interventions.

Role of competitive endogenous RNA networks in the pathogenesis of coronary artery disease

Background

The present study aimed to construct a network of competitive endogenous RNAs (ceRNAs) related to the pathogenesis of coronary artery disease (CAD), to provide a novel rationale for CAD treatment.

Methods

Bioinformatics methods were applied to screen for differentially expressed long non-coding RNAs (DElncRNAs), microRNAs (DEmiRNAs), and mRNAs (DEmRNAs) from the GSE68506, GSE59421, and GSE20129 datasets of the Gene Expression Omnibus (GEO) database. The miRcode database was used to predict lncRNA-binding miRNAs. The miRTarBase, miRDB, and TargetScan databases were used to predict the target genes of these miRNAs. An mRNA-miRNA-lncRNA ceRNA network of CAD was established.

Results

Between the CAD and normal control groups there were 264 DElncRNAs, 106 DEmiRNAs, and 1,879 DEmRNAs. We screened these differentially expressed gens (DEGs) respectively. There were 21 DElncRNAs, 13 DEmiRNAs, and 143 DEmRNAs in the ceRNA network by using Cytoscape application. The DEmRNAs were involved in the PI3K-Akt signaling pathway and the NF-κB signaling pathway. The key genes in the protein-protein interaction (PPI) network were HSP90AA1, CDKN1A, MCL1, MDM2, MAPK1, ABL1, LYN, CRK, CDK9, and FAS.

Conclusions

The ceRNA network constructed in this study identified new candidate molecules for the treatment of CAD, providing some more comprehensive and higher-quality choices for the target treatment of CAD.

Stress-induced differential gene expression in cardiac tissue

The stress response is adaptive and aims to guarantee survival. However, the persistence of a stressor can culminate in pathology. Catecholamines released as part of the stress response over activate beta adrenoceptors (β-AR) in the heart. Whether and how stress affects the expression of components of the intracellular environment in the heart is still, however, unknown. This paper used microarray to analyze the gene expression in the left ventricle wall of rats submitted to foot shock stress, treated or not treated with the selective β₂-AR antagonist ICI118,551 (ICI), compared to those of non-stressed rats also treated or not with ICI, respectively. The main findings were that stress induces changes in gene expression in the heart and that β₂-AR plays a role in this process. The vast majority of genes disregulated by stress were exclusive for only one of the comparisons, indicating that, in the same stressful situation, the profile of gene expression in the heart is substantially different when the β₂-AR is active or when it is blocked. Stress induced alterations in the expression of such a large number of genes seems to be part of stress-induced adaptive mechanism.

A Roadmap for Fixing the Heart: RNA Regulatory Networks in Cardiac Disease

With the continuous development of RNA biology and massive genome-wide transcriptome analysis, more and more RNA molecules and their functions have been explored in the last decade. Increasing evidence has demonstrated that RNA-related regulatory networks play an important role in a variety of human diseases, including cardiovascular diseases. In this review, we focus on RNA regulatory networks in heart disease, most of which are devastating conditions with no known cure. We systemically summarize recent discoveries of important new components of RNA regulatory networks, including microRNAs, long non-coding RNAs, and circular RNAs, as well as multiple regulators that affect the activity of these networks in cardiac physiology and pathology. In addition, this review covers emerging micropeptides, which represent short open reading frames (sORFs) in long non-coding RNA transcripts that may modulate cardiac physiology. Based on the current knowledge of RNA regulatory networks, we think that ongoing discoveries will not only provide us a better understanding of the molecular mechanisms that underlie heart disease, but will also identify novel biomarkers and therapeutic targets for the diagnosis and treatment of cardiac disease.

MicroRNAs as potential biomarkers in congenital heart surgery

OBJECTIVE

Pediatric congenital heart surgery (CHS) involves intracardiac, valvular, and vascular repairs. Accurate tools to aid short-term outcome prediction in pediatric CHS are lacking. Clinical scores, such as the vasoactive-inotrope score and ventilation index, are used to define outcome in clinical studies. MicroRNA-1-3p (miR-1) is expressed by both cardiomyocytes and vascular cells and is regulated by hypoxia. In adult patients, miR-1 increases in the circulation after open-heart cardiac surgery, suggesting its potential as a clinical biomarker. Thus, we investigated whether perioperative circulating miR-1 measurements can help predict post-CHS short-term outcomes in pediatric patients.

METHODS

Plasma miR-1 was retrospectively measured in a cohort of 199 consecutive pediatric CHS patients (median age 1.2 years). Samples were taken before surgery and at the end of the operation. Plasma miR-1 concentration was measured by reverse transcription-quantitative polymerase chain reaction and expressed as miR-1 copies/μL and as relative expression to spiked-in exogenous cel-miR-39.

RESULTS

Baseline plasma miR-1 did not vary across different diagnoses, increased during surgery (204-fold median relative increase, P < .001), and was associated with aortic crossclamp duration postoperatively (P < .001). Importantly, miR-1 levels at the end of the operation positively correlated with intensive care stay (P < .001), early severe cardiovascular events (P = .01), and with high vasoactive-inotrope score (P = .001) and ventilation index (P < .001), suggesting that miR-1 could accelerate the identification of patients with cardiopulmonary bypass-related ischemic complications, requiring more intensive support.

CONCLUSIONS

Our study suggests miR-1 as a novel potential circulating biomarker to predict early postoperative outcome and inform clinical management in pediatric heart surgery.

MicroRNA-1 facilitates hypoxia-induced injury by targeting NOTCH3

Cell proliferation, apoptosis, and autophagy have been reported to be related to myocardial ischemia injury. MicroRNAs have attracted wide attention on regulating cell proliferation, apoptosis, and autophagy. miR-1 expression has been reported to be dysregulated in cardiac tissue or cells with hypoxia, while the exact roles as well as underlying mechanism remain poorly understood. In this study, we investigated the potential roles of miR-1 in cell proliferation, apoptosis, and autophagy in hypoxia-treated cardiac injury and explored the underlying mechanism using H9c2 cells. Results showed that hypoxic stimulation inhibited cell proliferation and the expression of miR-1 but promoted cell apoptosis in H9c2 cells. Moreover, overexpression of miR-1 promoted cell apoptosis and inhibited cell proliferation and autophagy in H9c2 cells treated with hypoxia, while its knockdown played an opposite effect. In addition, bioinformatics, luciferase reporter, and RNA immunoprecipitation analyses indicated that NOTCH3 was a direct target of miR-1 and its upregulation reversed the effects of miR-1 on cell proliferation, apoptosis, and autophagy in hypoxia-treated H9c2 cells. Taken together, our data suggested that miR-1 promoted hypoxia-induced injury by targeting NOTCH3, indicating novel therapeutic targets for treatment of myocardial ischemia injury.

Potential microRNA-related targets in clearance pathways of amyloid-β: novel therapeutic approach for the treatment of Alzheimer's disease

Imbalance between amyloid-beta (Aβ) peptide synthesis and clearance results in Aβ deregulation. Failure to clear these peptides appears to cause the development of Alzheimer's disease (AD). In recent years, microRNAs have become established key regulators of biological processes that relate among others to the development and progression of neurodegenerative diseases, such as AD. This review article gives an overview on microRNAs that are involved in the Aβ cascade and discusses their inhibitory impact on their target mRNAs whose products participate in Aβ clearance. Understanding of the mechanism of microRNA in the associated signal pathways could identify novel therapeutic targets for the treatment of AD.

The Functional Analysis of Selenium-Related Genes and Magnesium-Related Genes in the Gene Expression Profile Microarray in the Peripheral Blood Mononuclear Cells of Keshan Disease

Keshan disease (KD) is an endemic cardiomyopathy with high mortality. Selenium (Se) deficiency is closely related to KD, while magnesium (Mg) plays many critical roles in the cardiovascular function. The molecular mechanism of KD pathogenesis is still unclear. Until now, we have not found any studies investigating the association between Se- or Mg-related genes and KD. In this study, oligonucleotide microarray analysis was used to identify the differentially expressed genes in the peripheral blood mononuclear cells between KD patients and normal controls. Next, human metabolome database (HMDB) was used to screen Se- and Mg-related genes. Function classification, gene pathway, and interaction network of Se- and Mg-related genes in KD peripheral blood mononuclear cells were defined by FunRich (functional enrichment analysis tool). Among 83 differentially expressed genes, five Se-related (DIO2, GPX1, GPX2, GPX4, and GPX7) and five Mg-related (ACSL6, EYA4, IDH2, PPM1A, and STK11) genes were recognized from HMDB. Two significant biological processes (energy pathways and metabolism), one molecular function (peroxidase activity), one biological pathway (glutathione redox reactions I), and one gene interaction network were constituted from Se-related and Mg-related genes. Se-related gene DIO2 and Mg-related genes STK11 and IDH2 may have key roles in the myocardial dysfunction of KD. However, we still have not obtained any interaction between Se-related gene and Mg-related gene. The interactions between RPS6KB1, PTEN, ATM, HSP90AA1, SNRK, PRKAA2, SMARCA4, HSPA1A, and STK11 may play important roles in the abnormal cardiac function of KD.

Reduction of miR-29a-3p induced cardiac ischemia reperfusion injury in mice via targeting Bax

The current study mainly aimed to evaluate the expression and the potential mechanism of miR-29a-3p in the hearts of mice after cardiac ischemia reperfusion (CIR) injury. Quantitative PCR was carried out to assess the relative levels of miR-29a-3p in the hearts of a CIR injury mouse model. To the best of our knowledge, the current study is the first to show that the level of miR-29a-3p was significantly decreased in the hearts of CIR injury mouse models compared with that of sham controls. Moreover, the authors found that decreased miR-29a-3p levels enhanced the production of reactive oxygen species in cardiomyocytes. Meanwhile, the inhibition of miR-29a-3p induced substantial cardiomyocyte apoptosis. Further study showed that the inhibition of miR-29a-3p decreased the activation of Akt and p38, suggesting a stress-induced self-regulatory mechanism after CIR injury in primary cardiomyocytes. A dual luciferase assay and western blot analysis showed that Bax was a target gene of miR-29a-3p. The authors also measured the level of miR-29a-3p in the plasma of 100 acute myocardial infarction (AMI) patients and found that circulating miR-29a-3p was significantly decreased in AMI patients. Receiver operating characteristic curve analysis showed that miR-29a-3p could be used to screen AMI patients from healthy controls. Hence, the authors of the current study propose that reduced miR-29a-3p levels in primary cardiomyocytes contribute to CIR injury-related apoptosis mainly by targeting Bax.

MiR-27 alleviates myocardial cell damage induced by hypoxia/reoxygenation via targeting TGFBR1 and inhibiting NF-κB pathway

MiR-27 prevents atherosclerosis by inhibiting inflammatory responses induced by lipoprotein lipase. Overexpression of miR-27b attenuates angiotensin-induced atrial fibrosis. Nevertheless, studies have rarely investigated on the effect of miR-27 in cardiomyocyte injury. H9c2 cells were transfected with miR-27 mimic/inhibitor. Then the cell proliferation was tested by MTT assay and the cell apoptosis was detected by flow cytometry. The luciferase activity assay was utilized to analyze the relationship between miR-27 and TGFBR1. Quantificational real-time polymerase chain reaction and western blot were utilized to detect the cardiomyocyte differentiation marker and nuclear factor kappa B (NF-κB) pathway. Our outcomes demonstrated that miR-27 expression was downregulated cardiomyocyte injury subjected to hypoxia/reoxygenation (H/R). Additionally, overexpression of miR-27 could significantly alleviate cardiomyocyte injury by regulating cell activity and apoptosis. The luciferase activity assay confirmed that transforming growth factor ß receptor 1 (TGFBR1) is a direct hallmark of miR-27. Besides, overexpression of miR-27 promoted the expression of TGFBR1 in H/R model. After transfection with miR-27 mimic/inhibitor, the expression of NF-κB pathway-related proteins was decreased/increased. Taken together, our data manifested that miR-27 repressed cardiomyocyte injury induced by H/R via mediating TGFBR1 and inhibiting NF-κB signaling pathway. Furthermore, miR-27/ TGFBR1 might be utilized as hopeful biomarkers for myocardial ischemia diagnosis and treatment.

An 85-Gene Coexpression Module for Progression of Hypertension-Induced Spontaneous Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) represents the most lethal form of stroke. We sought to identify potential genes that might contribute to progression of hypertension-induced spontaneous ICH (HIS-ICH). RNA-sequencing data set of cerebral vessel samples from HIS-ICH mice and normal mice was obtained from the Gene Expression Omnibus. Differential expression genes in HIS-ICH samples were obtained compared with normal samples followed by functional enrichment analysis. What is more, we explored the potential gene coexpression module (GCM) for HIS-ICH progression by using weighted gene coexpression network analysis. We further conducted protein-protein interaction network analysis for genes contained in GCM that was closely correlated with HIS-ICH to disclose their biological interactions. As a result, 554 genes were found to aberrantly express in HIS-ICH mice compared with normal mice, which were mainly associated with cancer-related pathways in addition to some well-known ICH-related pathways. A total of 28 GCMs were obtained, and darkturquoise module that contained 85 genes, which were closely associated with mitochondrion and hydrolase activity, was significantly correlated with HIS-ICH progression. Besides, we identified dense biological interactions among some genes in darkturquoise, such as Psma gene family and Hsp90a gene family. This study should shed new light on HIS-ICH progression and its treatment.

A microRNA’s journey to the center of the mitochondria

MicroRNAs (miRNAs) are known as the master regulators of gene expression, and for the last two decades our knowledge of their functional reach keeps expanding. Recent studies have shown that a miRNA’s role in regulation extends to extracellular and intracellular organelles. Several studies have shown a role for miRNA in regulating the mitochondrial genome in normal and disease conditions. Mitochondrial dysfunction occurs in many human pathologies, such as cardiovascular disease, diabetes, cancer, and neurological diseases. These studies have shed some light on regulation of the mitochondrial genome as well as helped to explain the role of miRNA in altering mitochondrial function and the ensuing effects on cells. Although the field has grown in recent years, many questions still remain. For example, little is known about how nuclear-encoded miRNAs translocate to the mitochondrial matrix. Knowledge of the mechanisms of miRNA transport into the mitochondrial matrix is likely to provide important insights into our understanding of disease pathophysiology and could represent new targets for therapeutic intervention. For this review, our focus will be on the role of a subset of miRNAs, known as MitomiR, in mitochondrial function. We also discuss the potential mechanisms used by these nuclear-encoded miRNAs for import into the mitochondrial compartment.

Listen to this article’s corresponding podcast at http://ajpheart.podbean.com/e/microrna-translocation-into-the-mitochondria/ .

Araloside C Prevents Hypoxia/Reoxygenation-Induced Endoplasmic Reticulum Stress via Increasing Heat Shock Protein 90 in H9c2 Cardiomyocytes

Araloside C (AsC) is a cardioprotective triterpenoid compound that is mainly isolated from Aralia elata. This study aims to determine the effects of AsC on hypoxia-reoxygenation (H/R)-induced apoptosis in H9c2 cardiomyocytes and its underlying mechanisms. Results demonstrated that pretreatment with AsC (12.5 μM) for 12 h significantly suppressed the H/R injury in H9c2 cardiomyocytes, including improving cell viability, attenuating the LDH leakage and preventing cardiomyocyte apoptosis. AsC also inhibited H/R-induced ER stress by reducing the activation of ER stress pathways (PERK/eIF2α and ATF6), and decreasing the expression of ER stress-related apoptotic proteins (CHOP and caspase-12). Moreover, AsC greatly improved the expression level of HSP90 compared with that in the H/R group. The use of HSP90 inhibitor 17-AAG and HSP90 siRNA blocked the above suppression effect of AsC on ER stress-related apoptosis caused by H/R. Taken together, AsC could reduce H/R-induced apoptosis possibly because it attenuates ER stress-dependent apoptotic pathways by increasing HSP90 expression.

Evaluation and control of miRNA-like off-target repression for RNA interference

RNA interference (RNAi) has been widely adopted to repress specific gene expression and is easily achieved by designing small interfering RNAs (siRNAs) with perfect sequence complementarity to the intended target mRNAs. Although siRNAs direct Argonaute (Ago), a core component of the RNA-induced silencing complex (RISC), to recognize and silence target mRNAs, they also inevitably function as microRNAs (miRNAs) and suppress hundreds of off-targets. Such miRNA-like off-target repression is potentially detrimental, resulting in unwanted toxicity and phenotypes. Despite early recognition of the severity of miRNA-like off-target repression, this effect has often been overlooked because of difficulties in recognizing and avoiding off-targets. However, recent advances in genome-wide methods and knowledge of Ago-miRNA target interactions have set the stage for properly evaluating and controlling miRNA-like off-target repression. Here, we describe the intrinsic problems of miRNA-like off-target effects caused by canonical and noncanonical interactions. We particularly focus on various genome-wide approaches and chemical modifications for the evaluation and prevention of off-target repression to facilitate the use of RNAi with secured specificity.

Myricitrin Protects Cardiomyocytes from Hypoxia/Reoxygenation Injury: Involvement of Heat Shock Protein 90

Modulation of oxidative stress is therapeutically effective in ischemia/reperfusion (I/R) injury. Myricitrin, a naturally occurring phenolic compound, is a potent antioxidant. However, little is known about its effect on I/R injury to cardiac myocytes. The present study was performed to investigate the potential protective effect of myricitrin against hypoxia/reoxygenation (H/R)-induced H9c2 cardiomyocyte injury and its underlying mechanisms. Myricitrin pretreatment improved cardiomyocyte viability, inhibited ROS generation, maintained the mitochondrial membrane potential, reduced apoptotic cardiomyocytes, decreased the caspase-3 activity, upregulated antiapoptotic proteins and downregulated proapoptotic proteins during H/R injury. Moreover, the potential targets of myricitrin was predicted using Discovery Studio software, and heat shock protein 90 (Hsp90) was identified as the main disease-related target. Further mechanistic investigation revealed that 17-AAG, a pharmacologic inhibitor of Hsp90, significantly blocked the myricitrin-induced cardioprotective effect demonstrated by increased apoptosis and ROS generation. These results suggested that myricitrin provides protection to H9c2 cardiomyocytes against H/R-induced oxidative stress and apoptosis, most likely via increased expression of Hsp90.

MiRNA Deregulation in Cardiac Aging and Associated Disorders

The prevalence of age-related diseases is increasing dramatically, among which cardiac disease represents the leading cause of death. Aging of the heart is characterized by various molecular and cellular hallmarks impairing both cardiomyocytes and noncardiomyocytes, and resulting in functional deteriorations of the cardiac system. The aging process includes desensitization of β-adrenergic receptor (βAR)-signaling and decreased calcium handling, altered growth signaling and cardiac hypertrophy, mitochondrial dysfunction and impaired autophagy, increased programmed cell death, low-grade inflammation of noncanonical inflammatory cells, and increased ECM deposition. MiRNAs play a fundamental role in regulating the processes underlying these detrimental changes in the cardiac system, indicating that MiRNAs are crucially involved in aging. Among others, MiR-34, MiR-146a, and members of the MiR-17-92 cluster, are deregulated during senescence and drive cardiac aging processes. It is therefore suggested that MiRNAs form possible therapeutic targets to stabilize the aged failing myocardium.

Population transcriptomes reveal synergistic responses of DNA polymorphism and RNA expression to extreme environments on the Qinghai-Tibetan Plateau in a predatory bird

Low oxygen and temperature pose key physiological challenges for endotherms living on the Qinghai-Tibetan Plateau (QTP). Molecular adaptations to high-altitude living have been detected in the genomes of Tibetans, their domesticated animals and a few wild species, but the contribution of transcriptional variation to altitudinal adaptation remains to be determined. Here we studied a top QTP predator, the saker falcon, and analysed how the transcriptome has become modified to cope with the stresses of hypoxia and hypothermia. Using a hierarchical design to study saker populations inhabiting grassland, steppe/desert and highland across Eurasia, we found that the QTP population is already distinct despite having colonized the Plateau <2000 years ago. Selection signals are limited at the cDNA level, but of only seventeen genes identified, three function in hypoxia and four in immune response. Our results show a significant role for RNA transcription: 50% of upregulated transcription factors were related to hypoxia responses, differentiated modules were significantly enriched for oxygen transport, and importantly, divergent EPAS1 functional variants with a refined co-expression network were identified. Conservative gene expression and relaxed immune gene variation may further reflect adaptation to hypothermia. Our results exemplify synergistic responses between DNA polymorphism and RNA expression diversity in coping with common stresses, underpinning the successful rapid colonization of a top predator onto the QTP. Importantly, molecular mechanisms underpinning highland adaptation involve relatively few genes, but are nonetheless more complex than previously thought and involve fine-tuned transcriptional responses and genomic adaptation.

Protective effects of Araloside C against myocardial ischaemia/reperfusion injury: potential involvement of heat shock protein 90

The present study was designed to investigate whether Araloside C, one of the major triterpenoid compounds isolated from Aralia elata known to be cardioprotective, can improve heart function following ischaemia/reperfusion (I/R) injury and elucidate its underlying mechanisms. We observed that Araloside C concentration‐dependently improved cardiac function and depressed oxidative stress induced by I/R. Similar protection was confirmed in isolated cardiomyocytes characterized by maintaining Ca²⁺ transients and cell shortening against I/R. Moreover, the potential targets of Araloside C were predicted using the DDI‐CPI server and Discovery Studio software. Molecular docking analysis revealed that Araloside C could be stably docked into the ATP/ADP‐binding domain of the heat shock protein 90 (Hsp90) protein via the formation of hydrogen bonds. The binding affinity of Hsp90 to Araloside C was detected using nanopore optical interferometry and yielded KD values of 29 μM. Araloside C also up‐regulated the expression levels of Hsp90 and improved cell viability in hypoxia/reoxygenation‐treated H9c2 cardiomyocytes, whereas the addition of 17‐AAG, a pharmacologic inhibitor of Hsp90, attenuated Araloside C‐induced cardioprotective effect. These findings reveal that Araloside C can efficiently attenuate myocardial I/R injury by reducing I/R‐induced oxidative stress and [Ca²⁺]_i overload, which was possibly related to its binding to the Hsp90 protein.

MitomiRs Keep the Heart Beating

In this chapter, we focus on the microRNAs (miRNAs or miRs) that have been found in the mitochondrial compartment, and target either mitochondrial or nuclear encoded genes present in mitochondria, leading to an alteration of mitochondrial function. We term this subset of miRNAs as "MitomiRs".