RNA sequencing analysis and atrial natriuretic peptide production in patients with dilated and ischemic cardiomyopathy

Gut microbiota and atrial cardiomyopathy

Atrial cardiomyopathy is a multifaceted heart disease characterized by structural and functional abnormalities of the atria and is closely associated with atrial fibrillation and its complications. Its etiology involves a number of factors, including genetic, infectious, immunologic, and metabolic factors. Recent research has highlighted the critical role of the gut microbiota in the pathogenesis of atrial cardiomyopathy, and this is consistent with the gut-heart axis having major implications for cardiac health. The aim of this work is to bridge the knowledge gap regarding the interactions between the gut microbiota and atrial cardiomyopathy, with a particular focus on elucidating the mechanisms by which gut dysbiosis may induce atrial remodeling and dysfunction. This article provides an overview of the role of the gut microbiota in the pathogenesis of atrial cardiomyopathy, including changes in the composition of the gut microbiota and the effects of its metabolites. We also discuss how diet and exercise affect atrial cardiomyopathy by influencing the gut microbiota, as well as possible future therapeutic approaches targeting the gut-heart axis. A healthy gut microbiota can prevent disease, but ecological dysbiosis can lead to a variety of symptoms, including the induction of heart disease. We focus on the pathophysiological aspects of atrial cardiomyopathy, the impact of gut microbiota dysbiosis on atrial structure and function, and therapeutic strategies exploring modulation of the microbiota for the treatment of atrial cardiomyopathy. Finally, we discuss the role of gut microbiota in the treatment of atrial cardiomyopathy, including fecal microbiota transplantation and oral probiotics or prebiotics. Our study highlights the importance of gut microbiota homeostasis for cardiovascular health and suggests that targeted interventions on the gut microbiota may pave the way for innovative preventive and therapeutic strategies targeting atrial cardiomyopathy.

RNA Helicase DDX5 Maintains Cardiac Function by Regulating CamkIIδ Alternative Splicing

BACKGROUND

Heart failure (HF) is a leading cause of morbidity and mortality worldwide. RNA-binding proteins are identified as regulators of cardiac disease; DDX5 (dead-box helicase 5) is a master regulator of many RNA processes, although its function in heart physiology remains unclear.

METHODS

We assessed DDX5 expression in human failing hearts and a mouse HF model. To study the function of DDX5 in heart, we engineered cardiomyocyte-specific Ddx5 knockout mice. We overexpressed DDX5 in cardiomyocytes using adeno-associated virus serotype 9 and performed transverse aortic constriction to establish the murine HF model. The mechanisms underlined were subsequently investigated using immunoprecipitation-mass spectrometry, RNA-sequencing, alternative splicing analysis, and RNA immunoprecipitation sequencing.

RESULTS

We screened transcriptome databases of murine HF and human dilated cardiomyopathy samples and found that DDX5 was significantly downregulated in both. Cardiomyocyte-specific deletion of Ddx5 resulted in HF with reduced cardiac function, an enlarged heart chamber, and increased fibrosis in mice. DDX5 overexpression improved cardiac function and protected against adverse cardiac remodeling in mice with transverse aortic constriction-induced HF. Furthermore, proteomics revealed that DDX5 is involved in RNA splicing in cardiomyocytes. We found that DDX5 regulated the aberrant splicing of Ca2+/calmodulin-dependent protein kinase IIδ (CamkIIδ), thus preventing the production of CaMKIIδA, which phosphorylates L-type calcium channel by serine residues of Cacna1c, leading to impaired Ca2+ homeostasis. In line with this, we found increased intracellular Ca2+ transients and increased sarcoplasmic reticulum Ca2+ content in DDX5-depleted cardiomyocytes. Using adeno-associated virus serotype 9 knockdown of CaMKIIδA partially rescued the cardiac dysfunction and HF in Ddx5 knockout mice.

CONCLUSIONS

These findings reveal a role for DDX5 in maintaining calcium homeostasis and cardiac function by regulating alternative splicing in cardiomyocytes, identifying the DDX5 as a potential target for therapeutic intervention in HF.

Transcriptomic Alterations in Spliceosome Components in Advanced Heart Failure: Status of Cardiac-Specific Alternative Splicing Factors

Heart failure (HF) is associated with global changes in gene expression. Alternative mRNA splicing (AS) is a key regulatory mechanism underlying these changes. However, the whole status of molecules involved in the splicing process in human HF is unknown. Therefore, we analysed the spliceosome transcriptome in cardiac tissue (n = 36) from control subjects and HF patients (with ischaemic (ICM) and dilated (DCM) cardiomyopathies) using RNA-seq. We found greater deregulation of spliceosome machinery in ICM. Specifically, we showed widespread upregulation of the E and C complex components, highlighting an increase in SNRPD2 (FC = 1.35, p < 0.05) and DHX35 (FC = 1.34, p < 0.001) mRNA levels. In contrast, we observed generalised downregulation of the A complex and cardiac-specific AS factors, such as the multifunctional protein PCBP2 (FC = -1.29, p < 0.001) and the RNA binding proteins QKI (FC = -1.35, p < 0.01). In addition, we found a relationship between SNPRD2 (an E complex component) and the left ventricular mass index in ICM patients (r = 0.779; p < 0.01). On the other hand, we observed the specific underexpression of DDX46 (FC = -1.29), RBM17 (FC = -1.33), SDE2 (FC = -1.35) and RBFOX1 (FC = -1.33), p < 0.05, in DCM patients. Therefore, these aetiology-related alterations may indicate the differential involvement of the splicing process in the development of ICM and DCM.

The Role of Furin and Its Therapeutic Potential in Cardiovascular Disease Risk

Furin is an important proteolytic enzyme, converting several proteins from inactive precursors to their active forms. Recently, proteo-genomic analyses in European and East Asian populations suggested a causal association of furin with ischaemic heart disease, and there is growing interest in its role in cardiovascular disease (CVD) aetiology. In this narrative review, we present a critical appraisal of evidence from population studies to assess furin's role in CVD risk and potential as a drug target for CVD. Whilst most observational studies report positive associations between furin expression and CVD risk, some studies report opposing effects, which may reflect the complex biological roles of furin and its substrates. Genetic variation in FURIN is also associated with CVD and its risk factors. We found no evidence of current clinical development of furin as a drug target for CVD, although several phase 1 and 2 clinical trials of furin inhibitors as a type of cancer immunotherapy have been completed. The growing field of proteo-genomics in large-scale population studies may inform the future development of furin and other potential drug targets to improve the treatment and prevention of CVD.

A Meta-Analysis Approach to Gene Regulatory Network Inference Identifies Key Regulators of Cardiovascular Diseases

Cardiovascular diseases (CVDs) represent a major concern for global health, whose mechanistic understanding is complicated by a complex interplay between genetic predisposition and environmental factors. Specifically, heart failure (HF), encompassing dilated cardiomyopathy (DC), ischemic cardiomyopathy (ICM), and hypertrophic cardiomyopathy (HCM), is a topic of substantial interest in basic and clinical research. Here, we used a Partial Correlation Coefficient-based algorithm (PCC) within the context of a meta-analysis framework to construct a Gene Regulatory Network (GRN) that identifies key regulators whose activity is perturbed in Heart Failure. By integrating data from multiple independent studies, our approach unveiled crucial regulatory associations between transcription factors (TFs) and structural genes, emphasizing their pivotal roles in regulating metabolic pathways, such as fatty acid metabolism, oxidative stress response, epithelial-to-mesenchymal transition, and coagulation. In addition to known associations, our analysis also identified novel regulators, including the identification of TFs FPM315 and OVOL2, which are implicated in dilated cardiomyopathies, and TEAD1 and TEAD2 in both dilated and ischemic cardiomyopathies. Moreover, we uncovered alterations in adipogenesis and oxidative phosphorylation pathways in hypertrophic cardiomyopathy and discovered a role for IL2 STAT5 signaling in heart failure. Our findings underscore the importance of TF activity in the initiation and progression of cardiac disease, highlighting their potential as pharmacological targets.

Computational screen to identify potential targets for immunotherapeutic identification and removal of senescence cells

To prioritize gene and protein candidates that may enable the selective identification and removal of senescent cells, we compared gene expression signatures from replicative senescent cells to transcriptomics and proteomics atlases of normal human tissues and cell types. RNA-seq samples from in vitro senescent cells (6 studies, 13 conditions) were analyzed for identifying targets at the gene and transcript levels that are highly expressed in senescent cells compared to their expression in normal human tissues and cell types. A gene set made of 301 genes called SenoRanger was established based on consensus analysis across studies and backgrounds. Of the identified senescence-associated targets, 29% of the genes in SenoRanger are also highly differentially expressed in aged tissues from GTEx. The SenoRanger gene set includes previously known as well as novel senescence-associated genes. Pathway analysis that connected the SenoRanger genes to their functional annotations confirms their potential role in several aging and senescence-related processes. Overall, SenoRanger provides solid hypotheses about potentially useful targets for identifying and removing senescence cells.

Landscape of RNA-binding proteins in diagnostic utility, immune cell infiltration and PANoptosis features of heart failure

Objective: Heart failure remains a global public health problem linked to rising morbidity and mortality. RNA-binding proteins (RBPs) are crucial regulators in post-transcriptionally determining gene expression. Our study aimed to comprehensively elucidate the diagnostic utility and biological roles of RBPs in heart failure.

Methods: Genomic data of human failing and nonfailing left ventricular myocardium specimens were retrieved from the GEO datasets. Heart failure-specific RBPs were screened with differential expression analyses, and RBP-based subtypes were clustered with consensus clustering approach. GSEA was implemented for comparing KEGG pathways across subtypes. RBP-based subtype-related genes were screened with WGCNA. Afterwards, characteristic genes were selected through integrating LASSO and SVM-RFE approaches. A nomogram based on characteristic genes was established and verified through calibration curve, decision curve and clinical impact curve analyses. The abundance of immune cell types was estimated with CIBERSORT approach.

Results: Heart failure-specific RBPs were determined, which were remarkably linked to RNA metabolism process. Three RBP-based subtypes (namely C1, C2, C3) were established, characterized by distinct pathway activities and PANoptosis gene levels. C2 subtype presented the highest abundance of immune cells, followed by C1 and C3. Afterwards, ten characteristic genes were selected, which enabled to reliably diagnose heart failure risk. The characteristic gene-based nomogram enabled to accurately predict risk of heart failure, with the excellent clinical utility. Additionally, characteristic genes correlated to immune cell infiltration and PANoptosis genes.

Conclusion: Our findings comprehensively described the roles of RBPs in heart failure. Further research is required for verifying the effectiveness of RBP-based subtypes and characteristic genes in heart failure.

Bioinformatics and Experimental Analyses Reveal NFIC as an Upstream Transcriptional Regulator for Ischemic Cardiomyopathy

Ischemic cardiomyopathy (ICM) caused by coronary artery disease always leads to myocardial infarction and heart failure. Identification of novel transcriptional regulators in ICM is an effective method to establish new diagnostic and therapeutic strategies. In this study, we used two RNA-seq datasets and one microarray dataset from different studies, including 25 ICM and 21 non-failing control (NF) samples of human left ventricle tissues for further analysis. In total, 208 differentially expressed genes (DEGs) were found by combining two RNA-seq datasets with batch effects removed. GO and KEGG analyses of DEGs indicated that the response to wounding, positive regulation of smooth muscle contraction, chromatin, PI3K-Akt signaling pathway, and transporters pathways are involved in ICM. Simple Enrichment Analysis found that NFIC-binding motifs are enriched in promoter regions of downregulated genes. The Gene Importance Calculator further proved that NFIC is vital. NFIC and its downstream genes were verified in the validating microarray dataset. Meanwhile, in rat cardiomyocyte cell line H9C2 cells, two genes (Tspan1 and Hopx) were confirmed, which decreased significantly along with knocking down Nfic expression. In conclusion, NFIC participates in the ICM process by regulating TSPAN1 and HOPX. NFIC and its downstream genes may be marker genes and potential diagnostic and therapeutic targets for ICM.

Nrf2 signaling in heart failure: expression of Nrf2, Keap1, antioxidant, and detoxification genes in dilated or ischemic cardiomyopathy

Increased levels of oxidative stress have been found with heart failure. Whether failing hearts express antioxidant and detoxification enzymes have not been addressed systematically. Nrf2 gene encodes a transcription factor that regulates the expression of antioxidant and detoxification genes. Using RNA-Seq data set from explanted hearts of 37 patients with dilated cardiomyopathy (DCM), 13 patients with ischemic cardiomyopathy (ICM), and 14 nonfailure (NF) donors as a control, we addressed whether failing hearts change the expression of Nrf2, its negative regulator Keap1, and antioxidant or detoxification genes. Significant increases in the ratio of Nrf2 to Keap1 were found to associate with DCM or ICM. Antioxidant genes showed decreased expression in both types of heart failure, including NQO1, SOD1, GPX3, GPX4, GSR, PRDX1, and TXNRD1. Detoxification enzymes, GCLM and EPHX1, also showed decreased expression, whereas the CYP1B1 transcript was elevated in both DCM and ICM. The genes encoding metal-binding protein ferritin were decreased, whereas five out of 12 metallothionein genes showed elevated expression. Our finding on Nrf2 gene expression has been validated by meta-analysis of seven independent data sets of microarray or RNA-Seq for differential gene expression in DCM and ICM from NF controls. In conclusion, minor elevation of Nrf2 gene expression is not coupled to increases in antioxidant and detoxification genes, supporting an impairment of Nrf2 signaling in patients with heart failure. Decreases in multiple antioxidant and detoxification genes are consistent with the observed increases of oxidative stress in failing hearts.

Insights into therapeutic targets and biomarkers using integrated multi-'omics' approaches for dilated and ischemic cardiomyopathies

At present, heart failure (HF) treatment only targets the symptoms based on the left ventricle dysfunction severity; however, the lack of systemic 'omics' studies and available biological data to uncover the heterogeneous underlying mechanisms signifies the need to shift the analytical paradigm towards network-centric and data mining approaches. This study, for the first time, aimed to investigate how bulk and single cell RNA-sequencing as well as the proteomics analysis of the human heart tissue can be integrated to uncover HF-specific networks and potential therapeutic targets or biomarkers. We also aimed to address the issue of dealing with a limited number of samples and to show how appropriate statistical models, enrichment with other datasets as well as machine learning-guided analysis can aid in such cases. Furthermore, we elucidated specific gene expression profiles using transcriptomic and mined data from public databases. This was achieved using the two-step machine learning algorithm to predict the likelihood of the therapeutic target or biomarker tractability based on a novel scoring system, which has also been introduced in this study. The described methodology could be very useful for the target or biomarker selection and evaluation during the pre-clinical therapeutics development stage as well as disease progression monitoring. In addition, the present study sheds new light into the complex aetiology of HF, differentiating between subtle changes in dilated cardiomyopathies (DCs) and ischemic cardiomyopathies (ICs) on the single cell, proteome and whole transcriptome level, demonstrating that HF might be dependent on the involvement of not only the cardiomyocytes but also on other cell populations. Identified tissue remodelling and inflammatory processes can be beneficial when selecting targeted pharmacological management for DCs or ICs, respectively.

Prediction of single-cell mechanisms for disease progression in hypertrophic remodelling by a trans-omics approach

Heart failure is a heterogeneous disease with multiple risk factors and various pathophysiological types, which makes it difficult to understand the molecular mechanisms involved. In this study, we proposed a trans-omics approach for predicting molecular pathological mechanisms of heart failure and identifying marker genes to distinguish heterogeneous phenotypes, by integrating multiple omics data including single-cell RNA-seq, ChIP-seq, and gene interactome data. We detected a significant increase in the expression level of natriuretic peptide A (Nppa), after stress loading with transverse aortic constriction (TAC), and showed that cardiomyocytes with high Nppa expression displayed specific gene expression patterns. Multiple NADH ubiquinone complex family, which are associated with the mitochondrial electron transport system, were negatively correlated with Nppa expression during the early stages of cardiac hypertrophy. Large-scale ChIP-seq data analysis showed that Nkx2-5 and Gtf2b were transcription factors characteristic of high-Nppa-expressing cardiomyocytes. Nppa expression levels may, therefore, represent a useful diagnostic marker for heart failure.

Assessment of human bioengineered cardiac tissue function in hypoxic and re-oxygenized environments to understand functional recovery in heart failure

Introduction

Myocardial recovery is one of the targets for heart failure treatment. A non-negligible number of heart failure with reduced ejection fraction (EF) patients experience myocardial recovery through treatment. Although myocardial hypoxia has been reported to contribute to the progression of heart failure even in non-ischemic cardiomyopathy, the relationship between contractile recovery and re-oxygenation and its underlying mechanisms remain unclear. The present study investigated the effects of hypoxia/re-oxygenation on bioengineered cardiac cell sheets-tissue function and the underlying mechanisms.

Methods

Bioengineered cardiac cell sheets-tissue was fabricated with human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CM) using temperature-responsive culture dishes. Cardiac tissue functions in the following conditions were evaluated with a contractile force measurement system: continuous normoxia (20% O₂) for 12 days; hypoxia (1% O₂) for 4 days followed by normoxia (20% O₂) for 8 days; or continuous hypoxia (1% O₂) for 8 days. Cell number, sarcomere structure, ATP levels, mRNA expressions and Ca²⁺ transients of hiPSC-CM in those conditions were also assessed.

Results

Hypoxia (4 days) elicited progressive decreases in contractile force, maximum contraction velocity, maximum relaxation velocity, Ca²⁺ transient amplitude and ATP level, but sarcomere structure and cell number were not affected. Re-oxygenation (8 days) after hypoxia (4 days) was associated with progressive increases in contractile force, maximum contraction velocity and relaxation time to the similar extent levels of continuous normoxia group, while maximum relaxation velocity was still significantly low even after re-oxygenation. Ca²⁺ transient magnitude, cell number, sarcomere structure and ATP level after re-oxygenation were similar to those in the continuous normoxia group. Hypoxia/re-oxygenation up-regulated mRNA expression of PLN.

Conclusions

Hypoxia and re-oxygenation condition directly affected human bioengineered cardiac tissue function. Further understanding the molecular mechanisms of functional recovery of cardiac tissue after re-oxygenation might provide us the new insight on heart failure with recovered ejection fraction and preserved ejection fraction.

Consensus Transcriptional Landscape of Human End-Stage Heart Failure

Background Transcriptomic studies have contributed to fundamental knowledge of myocardial remodeling in human heart failure (HF). However, the key HF genes reported are often inconsistent between studies, and systematic efforts to integrate evidence from multiple patient cohorts are lacking. Here, we aimed to provide a framework for comprehensive comparison and analysis of publicly available data sets resulting in an unbiased consensus transcriptional signature of human end-stage HF. Methods and Results We curated and uniformly processed 16 public transcriptomic studies of left ventricular samples from 263 healthy and 653 failing human hearts. First, we evaluated the degree of consistency between studies by using linear classifiers and overrepresentation analysis. Then, we meta-analyzed the deregulation of 14 041 genes to extract a consensus signature of HF. Finally, to functionally characterize this signature, we estimated the activities of 343 transcription factors, 14 signaling pathways, and 182 micro RNAs, as well as the enrichment of 5998 biological processes. Machine learning approaches revealed conserved disease patterns across all studies independent of technical differences. These consistent molecular changes were prioritized with a meta-analysis, functionally characterized and validated on external data. We provide all results in a free public resource (https://saezlab.shinyapps.io/reheat/) and exemplified usage by deciphering fetal gene reprogramming and tracing the potential myocardial origin of the plasma proteome markers in patients with HF. Conclusions Even though technical and sampling variability confound the identification of differentially expressed genes in individual studies, we demonstrated that coordinated molecular responses during end-stage HF are conserved. The presented resource is crucial to complement findings in independent studies and decipher fundamental changes in failing myocardium.

Superiority of proatrial natriuretic peptide in the prognostic power in patients with acute decompensated heart failure on hospital admission: comparison with B-type natriuretic peptide and other natriuretic peptide forms

Aims

There are significant differences in how atrial (A-type) and B-type natriuretic peptide (ANP and BNP) are secreted and metabolised, but there is little information available about the relative clinical significance of the two peptides. The aim of the present study was to investigate: (1) the association between the circulating level of each ANP molecular form and patient clinical background and (2) their prognostic power for patients with acute decompensated heart failure (ADHF).

Methods

We used specific chemiluminescence enzyme immunoassays to prospectively evaluate the levels of six bioactive molecular forms of ANP (pro-ANP, β-ANP and total ANP) and BNP (pro-BNP, N-terminal pro-BNP (NT-pro-BNP) and total BNP) in plasma samples collected from 173 patients with ADHF on their hospital admission.

Results

We found that pro-ANP levels were strongly associated with left ventricular (LV) size and ejection fraction (p<0.001), but were not associated with left atrial size. Percent pro-ANP ([pro-ANP/total ANP]x100) was also associated with LV size and function. During the follow-up term (median: 469 days), composite adverse events (all causes of death or rehospitalisation for HF) occurred in 67 patients (38.7 %). Pro-ANP was significantly associated with composite adverse events even after adjusting by estimated glomerular filtration rate (eGFR) (p<0.05). In contrast, NT-pro-BNP was not independent of eGFR in the multivariate analysis.

Conclusion

Circulating levels of pro-ANP are strongly associated with LV function and clinical outcomes of patients with ADHF. These findings suggest that during the acute phases of HF, pro-ANP has a prognostic power comparable with NT-pro-BNP independently of renal function.

Transcriptome analysis of human heart failure reveals dysregulated cell adhesion in dilated cardiomyopathy and activated immune pathways in ischemic heart failure

Background

Current heart failure (HF) treatment is based on targeting symptoms and left ventricle dysfunction severity, relying on a common HF pathway paradigm to justify common treatments for HF patients. This common strategy may belie an incomplete understanding of heterogeneous underlying mechanisms and could be a barrier to more precise treatments. We hypothesized we could use RNA-sequencing (RNA-seq) in human heart tissue to delineate HF etiology-specific gene expression signatures.

Results

RNA-seq from 64 human left ventricular samples: 37 dilated (DCM), 13 ischemic (ICM), and 14 non-failing (NF). Using a multi-analytic approach including covariate adjustment for age and sex, differentially expressed genes (DEGs) were identified characterizing HF and disease-specific expression. Pathway analysis investigated enrichment for biologically relevant pathways and functions. DCM vs NF and ICM vs NF had shared HF-DEGs that were enriched for the fetal gene program and mitochondrial dysfunction. DCM-specific DEGs were enriched for cell-cell and cell-matrix adhesion pathways. ICM-specific DEGs were enriched for cytoskeletal and immune pathway activation. Using the ICM and DCM DEG signatures from our data we were able to correctly classify the phenotypes of 24/31 ICM and 32/36 DCM samples from publicly available replication datasets.

Conclusions

Our results demonstrate the commonality of mitochondrial dysfunction in end-stage HF but more importantly reveal key etiology-specific signatures. Dysfunctional cell-cell and cell-matrix adhesion signatures typified DCM whereas signals related to immune and fibrotic responses were seen in ICM. These findings suggest that transcriptome signatures may distinguish end-stage heart failure, shedding light on underlying biological differences between ICM and DCM.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5213-9) contains supplementary material, which is available to authorized users.

Cardiac unloading by LVAD support differentially influences components of the cGMP-PKG signaling pathway in ischemic and dilated cardiomyopathy

Implantation of left ventricular assist devices (LVADs) as bridge to transplant in end-stage heart failure allows for analyzing reverse remodeling processes of the supported heart. Whether this therapy influences the cGMP-PKG signaling pathway, which is currently under thorough investigation for developing new heart failure therapeutics, is unknown. In fourteen end-stage heart failure patients (8 with dilated cardiomyopathy, DCM; 6 with ischemic cardiomyopathy, ICM) tissue specimens of left ventricles were collected at LVAD implantation and afterwards at receiver heart explantation, respectively. Then the expressions of key components of the cGMP-PKG signaling pathway were determined by polymerase chain reaction (ANP; BNP; natriuretic peptide receptor A, NPR-A; natriuretic peptide receptor C, NPR-C; neprilysin; NOS3; soluble guanylyl cyclase, sGC; PDE5; cGMP-dependent protein kinase G, PKG) and enzyme-linked immunosorbent assay (cGMP), respectively. Patients were predominantly male, 52 ± 10 years old, were receiving recommended heart failure therapy, and had their donor organ implanted after 351 ± 317 days of LVAD support. Except for more DCM patients with ICD therapy, no significant differences were detected between ICM and DCM, which also applies to the expression of cGMP-PKG pathway components at baseline. After LVAD support, ANP, NPR-C, and cGMP were significantly down-regulated and neprilysin, PDE5, and PKG I expressions were reduced with borderline significance in DCM, but not in ICM patients. Multiple significant correlations were found for expression differences (i.e., expression at LVAD implantation minus expression at heart transplantation) both in DCM and ICM, even though there was a closer connection between the NO and NP side of the cGMP-PKG pathway in DCM patients. Furthermore, duration of LVAD support negatively correlated with expression differences of PKG I, PDE5, and sGC in ICM, but not in DCM. Originating from the same activation level at LVAD implantation, cardiac unloading significantly alters key components of the cGMP-PKG pathway in DCM, but not in ICM patients. This etiology-specific regulation should be considered when analyzing therapeutic interventions with effects on this signaling pathway.

Association of rs2271037 and rs3749585 polymorphisms in CORIN with susceptibility to hypertension in a Chinese Han population: A case-control study

Corins are membrane-bound protease that regulates blood pressure by activating the natriuretic peptides. These pro-atrial natriuretic peptide convertases are essential for sodium homeostasis and normal blood pressure. CORIN variants have been identified in humans and other animals, but no studies of CORIN polymorphisms have been conducted in northeastern China. This study aims to investigate the association of 2 single nucleotide polymorphisms (SNPs) in CORIN (rs2271037 and rs3749585) with hypertension, as well as their potential interactions with some risk factors of hypertension in a Han population of northeastern China. A case-control study, including 402 patients with hypertension and 406 participants with normal blood pressure, was conducted in Liaoning province. SNP genotyping was carried out by high resolution melting (HRM) after polymerase chain reaction amplifications. Since rs3749585 is located in 3' untranslated region (UTR) of CORIN, in silico analysis was used to predict target micro RNAs on TargetScan, miRanda, and DIANA-microT. As a result, mutant T allele in rs2271037 (odds ratio [OR], 1.693; 95% confidence [CI], 1.528-1.877; p < 0.001) and C allele in rs3749585 (OR, 1.114; 95% CI 1.011-1.227; p = 0.029) increased the risk of hypertension, comparing with wild G allele and T allele, respectively. Patients with genotype TT (OR, 10.209; 95% CI, 6.414-16.250; p < 0.001) and GT (OR, 1.730; 95% CI, 1.226-2.443; p = 0.002) have higher risk of hypertension than those with genotype GG. SNP rs2271037 was significantly associated with susceptibility to hypertension in all genetic models (dominant model: OR, 2.879; 95% CI, 2.080-3.986; p < 0.001; recessive model: OR, 7.159; 95% CI, 4.779-10.724; p < 0.001; additive model: OR, 1.535; 95% CI, 1.163-2.027; p = 0.002). SNP rs3749585 was significantly correlated with hypertension susceptibility only in dominant model (OR, 1.533; 95% CI, 1.073-2.189; p = 0.019), but not in recessive model (OR, 1.220; 95% CI, 0.906-1.644; p = 0.191) or additive model (OR, 0.915; 95% CI, 0.694-1.205; p = 0.527). After adjusting for age, gender, body mass index (BMI), smoking, low-density lipoprotein cholesterol, and serum sodium level in logistic models, the same statistical results were obtained. Interaction study showed the association between CORIN polymorphisms and hypertension could be changed by overweight (BMI ≥ 25 kg/m²). In silico analyses implicated hsa-miR-495 as a target miRNA that potentially interacts with the 3' UTR of CORIN. In conclusion, polymorphisms of rs2271037 and rs3749585 in CORIN were significantly associated with hypertension in a Han population of northeastern China. The mutant-type T allele of rs2271037 and C allele of rs3749585 might increase the susceptibility to hypertension in this population.

Natural genetic variation of the cardiac transcriptome in non-diseased donors and patients with dilated cardiomyopathy

BACKGROUND

Genetic variation is an important determinant of RNA transcription and splicing, which in turn contributes to variation in human traits, including cardiovascular diseases.

RESULTS

Here we report the first in-depth survey of heart transcriptome variation using RNA-sequencing in 97 patients with dilated cardiomyopathy and 108 non-diseased controls. We reveal extensive differences of gene expression and splicing between dilated cardiomyopathy patients and controls, affecting known as well as novel dilated cardiomyopathy genes. Moreover, we show a widespread effect of genetic variation on the regulation of transcription, isoform usage, and allele-specific expression. Systematic annotation of genome-wide association SNPs identifies 60 functional candidate genes for heart phenotypes, representing 20% of all published heart genome-wide association loci. Focusing on the dilated cardiomyopathy phenotype we found that eQTL variants are also enriched for dilated cardiomyopathy genome-wide association signals in two independent cohorts.

CONCLUSIONS

RNA transcription, splicing, and allele-specific expression are each important determinants of the dilated cardiomyopathy phenotype and are controlled by genetic factors. Our results represent a powerful resource for the field of cardiovascular genetics.

The Involvement of Corin in the Progression of Diabetic Erectile Dysfunction in a Rat Model by Down-Regulating ANP /NO/cGMP Signal Pathway

This study was aimed to analyze the potential role of Corin in the procession of diabetic ED and to explore the underlying mechanism. Diabetic ED rat model was constructed and the characteristics of diabetic ED and control rats were recorded at 4, 8, 12, and 16 weeks. qRT-PCR and Western bloting were used to detected the mRNA and protein levels. Intracellular cGMP detection was accomplished using a commercial radioimmunoassay method. Vascular endothelial cell from rat corpus cavernosum spiral artery was isolated and transfected with si- Corin to analyzed the potential role of Corin. Cell viability was assessed using crystal violet. The results showed that diabetic ED rats showed significantly higher glucose level, and lower body weight, ICP level, and ICP/MAP ratio at 12 and 16 weeks in diabetic ED rats compared with control rats. The protein levels of Corin, atrial natriuretic peptide (ANP) and eNOS, and the level of cGMP were significantly down-regulated in corpus cavernosum in diabetic ED rats, revealing the potential role of Corin in NO-associated diabetic ED. Further, studies proved that defect of Corin not only inhibited the vascular endothelial cell viability in high-glucose condition, but also suppressed ANP, eNOS, and cGMP expression in vascular endothelial cells. To sum up, Corin contributes to the progression of diabetic ED and the underlying mechanism is associated with the down-regulation of ANP /NO/cGMP signal pathway. J. Cell. Biochem. 118: 2325-2332, 2017. © 2017 Wiley Periodicals, Inc.

New Altered Non-Fibrillar Collagens in Human Dilated Cardiomyopathy: Role in the Remodeling Process

Background

In dilated cardiomyopathy (DCM), cardiac failure is accompanied by profound alterations of extracellular matrix associated with the progression of cardiac dilation and left ventricular (LV) dysfunction. Recently, we reported alterations of non-fibrillar collagen expression in ischemic cardiomyopathy linked to fibrosis and cardiac remodeling. We suspect that expression changes in genes coding for non-fibrillar collagens may have a potential role in DCM development.

Objectives

This study sought to analyze changes in the expression profile of non-fibrillar collagen genes in patients with DCM and to examine relationships between cardiac remodeling parameters and the expression levels of these genes.

Methods and Results

Twenty-three human left ventricle tissue samples were obtained from DCM patients (n = 13) undergoing heart transplantation and control donors (n = 10) for RNA sequencing analysis. We found increased mRNA levels of six non-fibrillar collagen genes, such as COL4A5, COL9A1, COL21A1, and COL23A1 (P < 0.05 for all), not previously described in DCM. Protein levels of COL8A1 and COL16A1 (P < 0.05 for both), were correspondingly increased. We also identified TGF-β1 significantly upregulated and related to both COL8A1 and COL16A1. Interestingly, we found a significant relationship between LV mass index and the gene expression level of COL8A1 (r = 0.653, P < 0.05).

Conclusions

In our research, we identified new non-fibrillar collagens with altered expression in DCM, being COL8A1 overexpression directly related to LV mass index, suggesting that they may be involved in the progression of cardiac dilation and remodeling.

FTY720 (Gilenya) treatment prevents spontaneous autoimmune myocarditis and dilated cardiomyopathy in transgenic HLA-DQ8-BALB/c mice

Although dilated cardiomyopathy (DCM) is often caused by viral infections, it frequently involves autoimmune mechanisms associated with particular HLA-DR and DQ alleles. Our homozygous HLA-DQ8Ab(0) transgenic mice in the BALB/c background (HLA-DQ8(BALB/c)-Tg) developed early and progressive fatal heart failure from 4 to 5 weeks of age. Clinical signs of the disease included cyanotic eyes, tachycardia with dyspnea (from pale to cyanotic limbs), and terminal whole body edema. Sick mice had extremely dilated hearts, enlarged liver and spleen, and pleural/peritoneal effusion. Histology of the heart showed extensive heart muscle destruction with signs of fibrosis. The autoimmune nature of the disease was shown by high titers of antimyosin antibodies in the sera and IgG deposits in sick heart muscles, as well as focal neutrophil, T cell, and macrophage infiltration of the heart muscle. The sera of the sick mice showed a granular staining pattern on sections of healthy heart muscle. Quantitative analyses of DCM-specific gene expression studies revealed that sets of genes are involved in inflammation, hypoxia, and fibrosis. Treatment with FTY720 (Fingolimod/Gilenya) protected animals from the development of cardiomyopathy. HLA-DQ8(BALB/c)-Tg mice represent a spontaneous autoimmune myocarditis model that may provide a useful tool for studying the autoimmune mechanism of DCM and testing immunosuppressive drugs.

Corin is down-regulated and exerts cardioprotective action via activating pro-atrial natriuretic peptide pathway in diabetic cardiomyopathy

Background

Diabetic cardiomyopathy (DCM), a fatal cardiovascular complication of diabetes mellitus, often leads to progressive heart failure, however its pathogenesis remains unclear. Corin, a cardiac serine protease, is responsible for converting pro-atrial natriuretic peptide (pro-ANP) to biologically active atrial natriuretic peptide (ANP). It has been well established that corin deficiency is associated with the progression of hypertension, cardiac hypertrophy and heart failure. However, because the involvement of corin-mediated pro-ANP processing in DCM has not been clarified, this study aims to investigate the role of corin in the pathogenesis of DCM.

Methods

Diabetes mellitus was induced by a single intraperitoneal injection of streptozotocin (STZ 65 mg/kg) to Sprague–Dawley rats (180–220 g). DCM was confirmed by monitoring continuously transthoracic echocardiography every 4 weeks and hemodynamic measurements at 20 weeks. Myocardial disorder and fibrosis were detected by HE staining and Masson’s trichrome staining. The mRNA and protein levels of corin and ANP in rat hearts and cardiomyocytes were determined by quantitative real-time PCR, western blotting and immunohistochemical staining, respectively. H9c2 cardiomyoblasts proliferation was detected by MTT colorimetric assay and viable cell counting with trypan blue. The effect of Corin-siRNA H9c2 cardiomyoblasts on EA.hy926 cells migration was measured by the wound healing scratch assay.

Results

The corin and ANP expression in mRNA and protein levels was decreased in DCM rat hearts. Corin and ANP levels of neonatal rat cardiomyocytes and H9c2 cardiomyoblasts treated with high glucose were significantly lower than that of normal glucose treated. Precisely, corin and ANP levels decreased in DCM rats at 12, 16, 20 and 33 weeks; neonatal cardiomyocytes and H9c2 cardiomyoblasts treated with high glucose at 36, 48 and 60 h demonstrated significant reduction in corin and ANP levels. Corin-siRNA H9c2 cardiomyoblasts showed decreased proliferation. Culture supernatants of Corin-siRNA H9c2 cardiomyoblasts prevented endothelial cell line EA.hy926 migration in the wound healing scratch assay. Furthermore, iso-lectin expression in arteriole and capillary endothelium was down-regulated in DCM rats.

Conclusions

Our results indicate that corin plays an important role in cardioprotection by activating pro-atrial natriuretic peptide pathway in DCM. Corin deficiency leads to endothelial dysfunction and vascular remodeling.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-015-0298-9) contains supplementary material, which is available to authorized users.

Proprotein convertases in atherogenesis

PURPOSE OF REVIEW

The proprotein convertases subtilisin/kexin (PCSKs) are endoproteases identified as activators of precursors from hormones and peptides. On the basis of the variety of substrates and regulation in disease, they have been recognized as mediators in atherogenesis. The discovery of PCSK9, which regulates low-density lipoprotein receptor cell membrane availability, has led to a resurgence of interest in these enzymes and their function in cardiovascular diseases.

RECENT FINDINGS

Recent data demonstrate that PCSKs are expressed in human atheroma and are regulated in animal models of atherosclerosis. In animal models, inhibition of PCSKs, such as PCSK3, affects cell proliferation and migration as well as inflammation, reducing atherosclerosis. In addition, targeting PCSK9 lowers cholesterol levels and has now been demonstrated to lessen vascular lesion formation in mice. Experimentally investigated novel anti-PCSK9 strategies include genome editing and vaccination. Furthermore, studies show that PCSKs contribute to the initiation and progression of cardiometabolic risk factors, such as insulin resistance and obesity.

SUMMARY

PCSKs affect cardiovascular diseases on multiple levels, including atherosclerotic lesion formation as well as their contribution to cardiometabolic risk factors. PCSK9 is a key regulator of plasma cholesterol levels, thereby potentially affecting atherosclerosis and has rapidly emerged as a pharmacological target.

Construction of microRNA and transcription factor regulatory network based on gene expression data in cardiomyopathy

Background

Cardiomyopathy is a progressive myocardial disorder. Here, we attempted to reveal the possible mechanism of cardiomyopathy at the transcription level with the roles of microRNAs (miRNAs) and transcription factors (TFs) taken into account.

Method

We firstly identified differentially expressed genes (DEGs) between cardiomyopathy patients and controls with data from the gene expression omnibus (GEO) database. DEGs were associated with the canonical pathways, molecular and cellular functions, physiological system development and function in the Ingenuity Knowledge Base by using the Ingenuity Pathway Analysis (IPA) software. TFs and miRNAs that DEGs significantly enriched were identified and a double-factor regulatory network was constructed.

Results

A total of 1,680 DEGs were identified. The DEGs were enriched for various pathways, with glucocorticoid receptor signaling as the most significant. A double-factor regulatory network was constructed, including seven TFs and two miRNAs. A subnetwork under the regulation of MEF2C and SRF was also constructed to illustrate their regulatory effects on cardiac functions.

Conclusion

Our results may provide new understanding of cardiomyopathy and may facilitate further therapeutic studies.