RGS6 drives cardiomyocyte death following nucleolar stress by suppressing Nucleolin/miRNA-21

Novel Metabolites Genetically Linked to Salt Sensitivity of Blood Pressure: Evidence from mGWAS in Chinese Population

This study aims to identify genetically influenced metabolites (GIMs) associated with SSBP and elucidate their regulatory pathways through metabolome genome-wide association studies (mGWASs). Untargeted metabolomics and genome-wide genotyping were performed on 54 participants from the Systematic Epidemiological Study of Salt Sensitivity (EpiSS). The mGWAS was conducted on 970 plasma metabolites, and their potential biological mechanisms were explored. The multivariable logistic regression model and mendelian randomization (MR) were employed to investigate the association and causal relationship between GIMs and SSBP. Metabolomic analysis was performed on 100 subjects in the replication analysis to validate the GIMs identified in the discovery set and their causal association with SSBP. The mGWAS revealed associations between 1485 loci and 18 metabolites. After performing linkage disequilibrium analysis, 368 independent mQTLs were identified and annotated to 141 genes. These functional genes were primarily implicated in the signal transduction of sinoatrial node and atrial cardiac muscle cells. Five key genes were identified using CytoHubba, including CAMK2A, TIAM1, RYR2, RBFOX1, and NRXN3. One-sample MR analysis revealed 14 GIMs with causal associations to SSBP, with LysoPC (0:0/22:5n-3) positively associated with SSBP (p < 0.05). The causal relationship between Phe-lle and SSBP was validated in the replication analysis. This study elucidates the genetic regulatory mechanisms underlying metabolites and identifies GIMs that are causally associated with SSBP. These findings provide insights into identifying metabolic biomarkers of SSBP and characterizing its genetic and metabolic regulation mechanisms.

FNDC5/irisin mitigates the cardiotoxic impacts of cancer chemotherapeutics by modulating ROS-dependent and -independent mechanisms

Cardiotoxicity remains a major limiting factor in the clinical implementation of anthracycline chemotherapy. Though the etiology of doxorubicin-dependent heart damage has yet to be fully elucidated, the ability of doxorubicin to damage DNA and trigger oxidative stress have been heavily implicated in the pathogenesis of chemotherapy-associated cardiomyopathy. Here, we demonstrate that fibronectin type III domain-containing protein 5 (FNDC5), the precursor protein for myokine irisin, is depleted in the hearts of human cancer patients or mice exposed to chemotherapeutics. In cardiomyocytes, restoration of FNDC5 expression was sufficient to mitigate reactive oxygen species (ROS) accumulation and apoptosis following doxorubicin exposure, effects dependent on the irisin encoding domain of FNDC5 as well as signaling via the putative irisin integrin receptor. Intriguingly, we identified two parallel signaling cascades impacted by FNDC5 in cardiomyocytes: the ROS-driven intrinsic mitochondrial apoptosis pathway and the ROS-independent Ataxia Telangiectasia and Rad3-Related Protein (ATR)/Checkpoint Kinase 1 (Chk1) pathway. In fact, FNDC5 forms a co-precipitable complex with Chk1 alluding to possible intracellular actions for this canonically membrane-associated protein. Whereas FNDC5 overexpression in murine heart was cardioprotective, introduction of FNDC5-targeted shRNA into the myocardium was sufficient to trigger Bax up-regulation, ATR/Chk1 activation, oxidative stress, cardiac fibrosis, loss of ventricular function, and compromised animal survival. The detrimental impact of FNDC5 depletion on heart function could be mitigated via treatment with a Chk1 inhibitor identifying Chk1 hyperactivity as a causative factor in cardiac disease. Though our data point to the potential clinical utility of FNDC5/irisin-targeted agents in the treatment of chemotherapy-induced cardiotoxicity, we also found significant down regulation in FNDC5 expression in the hearts of aged mice that attenuated the cardioprotective impacts of FNDC5 overexpression following doxorubicin exposure. Together our data underscore the importance of FNDC5/irisin in maintenance of cardiac health over the lifespan.

G protein regulation by RGS proteins in the pathophysiology of dilated cardiomyopathy

Regulators of G protein signaling (RGS) proteins fine-tune signaling via heterotrimeric G proteins to maintain physiologic homeostasis in various organ systems of the human body including the brain, kidney, heart, and vasculature. Impaired regulation of G protein signaling by RGS proteins is implicated in the pathogenesis of several human diseases including various forms of cardiomyopathy such as hypertrophic cardiomyopathy and dilated cardiomyopathy (DCM). Both genetic and nongenetic changes that impinge on G protein signaling in cardiomyocytes are implicated in the etiology of DCM, and there is accumulating evidence that such genetic and nongenetic changes affecting G protein signaling in cell types other than cardiomyocytes could serve as a DCM trigger in humans. This review discusses and highlights mammalian RGS proteins and their roles in cardiac physiology and disease, with a specific focus on the current understanding of the etiology of DCM and the pathogenic roles of RGS proteins that are prominently expressed in the cardiovascular system. Growing evidence suggests that defects in G protein regulation by RGS proteins in the cardiovascular system likely contribute to cardiomyocyte structural damage and decreased contractile function that hallmark DCM. Further studies that enhance the understanding of the dynamics of G protein regulation by RGS proteins in several cell types in the myocardium and the vasculature are critical to gaining more insight into the etiology of DCM and heart failure, and to the identification of novel therapeutic targets.

Transforming Cardiotoxicity Detection in Cancer Therapies: The Promise of MicroRNAs as Precision Biomarkers

Cardiotoxicity (CDTX) is a critical side effect of many cancer therapies, leading to increased morbidity and mortality if not addressed. Early detection of CDTX is essential, and while echocardiographic measures like global longitudinal strain offer promise in identifying early myocardial dysfunction, the search for reliable biomarkers continues. MicroRNAs (miRNAs) are emerging as important non-coding RNA molecules that regulate gene expression post-transcriptionally, influencing key biological processes such as the cell cycle, apoptosis, and stress responses. In cardiovascular diseases, miRNAs have demonstrated potential as biomarkers due to their stability in circulation and specific expression patterns that reflect pathological changes. Certain miRNAs have been linked to CDTX and hold promise for early detection, prognosis, and therapeutic targeting. These miRNAs not only assist in identifying early cardiac injury, but also offer opportunities for personalized interventions by modulating their expression to influence disease progression. As research advances, integrating miRNA profiling with traditional diagnostic methods could enhance the management of CDTX in cancer patients, paving the way for improved patient outcomes and more tailored therapeutic strategies. Further clinical studies are essential to validate the clinical utility of miRNAs in managing CDTX.

Heart failure with preserved ejection fraction in pigs causes shifts in posttranscriptional checkpoints

Left ventricular pressure overload (LVPO) can lead to heart failure with a preserved ejection fraction (HFpEF) and LV chamber stiffness (LV Kc) is a hallmark. This project tested the hypothesis that the development of HFpEF due to an LVPO stimulus will alter posttranscriptional regulation, specifically microRNAs (miRs). LVPO was induced in pigs (n = 9) by sequential ascending aortic cuff and age- and weight-matched pigs (n = 6) served as controls. LV function was measured by echocardiography and LV Kc by speckle tracking. LV myocardial miRs were quantified using an 84-miR array. Treadmill testing and natriuretic peptide-A (NPPA) mRNA levels in controls and LVPO were performed (n = 10, n = 9, respectively). LV samples from LVPO and controls (n = 6, respectively) were subjected to RNA sequencing. LV mass and Kc increased by over 40% with LVPO (P < 0.05). A total of 30 miRs shifted with LVPO of which 11 miRs correlated to LV Kc (P < 0.05) that mapped to functional domains relevant to Kc such as fibrosis and calcium handling. LVPO resulted in reduced exercise tolerance (oxygen saturation, respiratory effort) and NPPA mRNA levels increased by fourfold (P < 0.05). RNA analysis identified several genes that mapped to specific miRs that were altered with LVPO. In conclusion, a specific set of miRs are changed in a large animal model consistent with the HFpEF phenotype, were related to LV stiffness properties, and several miRs mapped to molecular pathways that may hold relevance in terms of prognosis and therapeutic targets.NEW & NOTEWORTHY Heart failure with preserved ejection fraction (HFpEF) is an ever-growing cause for the HF burden. HFpEF is particularly difficult to treat as the mechanisms responsible for this specific form of HF are poorly understood. Using a relevant large animal model, this study uncovered a unique molecular signature with the development of HFpEF that regulates specific biological pathways relevant to the progression of this ever-growing cause of HF.