Abstract
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.
Introduction
Heart failure is a frequent complex clinical syndrome of symptoms and signs triggered by structural or functional abnormality that leads to impaired cardiac output (Packer et al., 2021b), which remains a growing public health issue affecting about 26 million individuals globally (). Typically, in accordance with left ventricular ejection fraction (LVEF), heart failure is categorized as preserved (HFpEF) and reduced ejection fraction (HFrEF) (). HFpEF is a filling issue because of muscle stiffness reducing left ventricular chamber size or left atrial dilation, while HFrEF is usually described as a mechanical left ventricular pump issue (Mascolo et al., 2022). Therapeutic strategies of above two types differ. Substantial evidence suggests that sequential drug treatment improves clinical outcomes in patients with HFrEF (). Differently, no treatment options show prognostic benefits and symptom controlling as the sole management regimen of HFpEF patients (Packer et al., 2021a). Reduction of associated hospital readmission rate and clinical and economic burden remains a pivotal issue in modern cardiovascular medicine (Piepoli et al., 2022). Biomarkers that reflect the pathophysiological processes of heart failure progression can aid clinicians in the early diagnosis and management of heart failure patients.
RNA binding proteins (RBPs) control RNA fate from synthesis to decay, the expression and roles of which are highly determined by detailed networks of transcriptional, post-transcriptional as well as post-translational machinery (). They are implicated in pathological manifestations of heart failure. For instance, RBPs have widespread translational control of human cardiac fibroblast activation (). RNA binding protein 24 loss enables to disrupt global alternative splicing as well as results in heart failure (). RNA-binding protein RBM20 weakens splicing to orchestrate cardiac pre-mRNA processing, and contributes to the pathogenesis of heart failure (). RBP HuR-mediated SCN5A mRNA stability represses arrhythmic risk in heart failure (Zhou et al., 2018). Knockdown of RNA binding motif-20-based titin splicing system can upregulate compliant titins, and thus ameliorates diastolic function and exercise tolerance in heart failure (Methawasin et al., 2016). Despite this, comprehensive analyses of RBPs in heart failure are lacking. Accumulated evidence demonstrates that PANoptosis (apoptosis, necroptosis, together with pyroptosis) mediates heart failure progression and possesses promising therapeutic implications (Zhang et al., 2016; Zeng et al., 2019; ). Nonetheless, the mechanisms of RBPs underlying PANoptosis remain indistinct in hear failure. Our study comprehensively evaluated RBP-based molecular subtypes and relevant characteristic genes for heart failure, unveiling the crucial roles of RBPs in pathophysiological process of heart failure as well as providing reliable targets for diagnosing heart failure risk.
Materials and methods
Heart failure expression profiling
This study downloaded the expression profiling of human heart failure from the Gene Expression Omnibus (GEO) repository. The GSE5406 dataset comprised microarray expression profiles of 194 human failing left ventricular (LV) myocardium specimens and 16 human nonfailing control LV myocardium specimens on the Affymetrix platform (). Additionally, we acquired microarray expression profiles of 177 human failing LV myocardium specimens and 136 human control specimens from the GSE57338 dataset on the basis of the Affymetrix platform (). Above expression profiles were merged, and removal of batch effects was implemented utilizing sva package (). Four independent datasets were utilized as external verification sets as follows: the GSE76701 dataset comprising expression profiles of 4 non-failing and 4 failing LV hearts (); the GSE55296 dataset containing RNA-seq data of human hearts from 26 heart failure patients and 10 healthy controls (Tarazón et al., 2014); the GSE86569 dataset with expression profiling of LV hearts from 12 HFrEF and 20 HFpEF patients; the GSE3585 dataset including expression profiles of 5 non-failing and 7 failing LV hearts.
Screening heart failure-specific RBPs
Totally, 1,542 RBPs were collected from previously published literature (Supplementary Table S1) (). Expression values of RBPs were compared between human failing and nonfailing LV myocardium specimens through limma package (Ritchie et al., 2015). RBPs with adjusted p < 0.05 and |fold-change|>1.5 were regarded as heart failure-specific RBPs. Targets of RBPs were predicted through starBase database.
Functional enrichment analyses
Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of RBPs with adjusted p < 0.05 were implemented utilizing clusterprofiler package (Yu et al., 2012). Terms with adjusted p < 0.05 were regarded as significant enrichment.
Consensus clustering analyses
Through ConsensusClusterPlus package (Wilkerson and Hayes, 2010), on the basis of RBPs with adjusted p < 0.05, consensus clustering analyses of heart failure specimens were run in accordance with the following parameters: item resampling, proportion of items to sample: 80%; gene resampling, proportion of features to sample: 80%; a maximum evaluated k, maximum clustering number to evaluate: 9; resampling, number of subsamples: 1,000; agglomerative hierarchical clustering algorithm): ‘hc’ (hclust); and distance: ‘pearson’ (1 - Pearson correlation). The RBP-based subtype classification was verified through principal component analyses (PCA).
Gene set enrichment analyses
GSEA methodology (Subramanian et al., 2005) was utilized for the comparisons of KEGG pathways across RBP-based subtypes. The “c2.cp.kegg.v7.4.symbols” gene set from the Molecular Signatures Database () was employed as a reference set, with the criteria of p-value<0.05.
Weighted gene co-expression network analyses
Expression profiling of the merged GSE5406 and GSE57338 datasets was extracted for conducting WGCNA utilizing WGCNA package (). Sample clustering was implemented for testing whether there were outlier specimens. Soft threshold power value was determined for constructing a scale-free topology network. Afterwards, the adjacency matrix was converted to the topological overlap matrix (TOM). In accordance with the TOM-based dissimilarity, distinct co-expression modules were clustered. Associations of modules and RBP-based subtypes were then evaluated. The module with the strongest correlation to RBP-based subtypes was screened, and the genes in this module were regarded as RBP-based subtype-related genes.
Protein-protein interaction analyses
RBP-based subtype-related genes were imported into the Search Tool for the Retrieval of Interacting Genes (STRING) online platform (https://www.string-db.org) (Szklarczyk et al., 2021). The interactions between their protein products were retrieved according to the default criteria. Utilizing MCODE plug-in of Cytoscape software (), PPI subnetwork and hub genes were obtained following the selection criteria of degree cutoff = 2, node score cutoff = 0.2, haircut = true, Fluff = false, K-core = 2 Max, and depth from seed = 100.
Selection of characteristic genes with two machine learning approaches
Characteristic RBP-based subtype-related genes were selected utilizing two machine learning approaches: least absolute shrinkage and selection operator regression (LASSO) as well as support vector machine recursive feature elimination (SVM-RFE). Through glmnet package (), LASSO was run and penalty parameter λ tuning was implemented using ten-fold cross-validation. Additionally, the best variables were selected with ten-fold cross-validation utilizing SVM-RFE algorithm. Afterwards, characteristic genes were determined through intersection of LASSO- and SVM-RFE-derived results.
Establishment of a nomogram
A nomogram was established on the basis of characteristic genes via rms package. The accuracy of the nomogram in predicting risk probabilities was evaluated with calibration curve. Decision curve analyses represent a novel approach for assessing clinical usefulness, which were utilized to evaluate the clinical utility of the nomogram. Clinical impact curves were drawn for assessing the clinical usefulness and applicability net benefits of the nomogram with the optimal diagnostic value.
Immune cell estimations
CIBERSORT (Newman et al., 2015) is an approach on the basis of the gene expression matrix for reliably estimating the relative abundance of 24 immune cell types in tissue specimens. CIBERSORT analyses were utilized for comparing differences in distinct immune cell types between groups. Spearman correlation analyses were implemented for exploring interactions between infiltrating immune cell types and characteristic genes.
Connectivity map (CMap) analysis
Heart failure-specific RBPs were utilized to query the CMap database (https://clue.io/). Compounds with p < 0.05 were selected as potential therapeutic drugs for heart failure based upon transcriptome data. The mode of action (MoA) of these compounds was then analyzed.
Statistical analyses
R software (www.r-project.org; version 3.6.1) was employed for all statistics analysis processes. Comparison analyses between groups were implemented utilizing Wilcoxon or Kruskal-Wallis test. The diagnostic efficacy of characteristic genes or nomogram was evaluated with receiver operator characteristic (ROC) curves along with area under the curve (AUC) calculation. Pearson or Spearmon correlation test was implemented for interactions between variables. p < 0.05 was considered statistically significant for all analysis process.
Results
Analyses of heart failure-specific RBPs
Our study collected and merged two heart failure expression profiling datasets (GSE5406, and GSE57338), and batch effects were corrected for subsequent analyses (Figures 1A,B). To determine heart failure-specific RBPs, differential expression analyses were implemented. In accordance with adjusted p < 0.05 and |fold-change|>1.5, five RBPs (EIF1AY, RPS4Y1, DDX3Y, RNASE2, and CSDC2) were found in heart failure LV myocardium specimens in comparison to nonfailing controls (Figures 1C,D). Afterwards, we predicted potential downstream targets of RBPs with adjusted p < 0.05 through starBase database. As depicted in Figure 1E, 18 targets (SERPINA3, FCN3, LUM, ASPN, IL1RL1, SFRP4, CD163, MYOT, OGN, MXRA5, LYVE1, MYH6, PLA2G2A, CYP4B1, SERPINE1, HBB, NPPA, and EIF1AY) had the potential binding sites of RBPs, which were differentially expressed in heart failure LV myocardium specimens in contrast to nonfailing controls. Biological functions and pathways of RBPs with adjusted p < 0.05 were then probed. Biological processes such as RNA/mRNA/peptide/ncRNA metabolic processes, RNA processing, and translation were both remarkably linked to up- and down-regulated RBPs (Figures 1F,G), indicating their essential roles in modulating gene expression. Additionally, RBPs with adjusted p < 0.05 closely correlated to multiple cellular components (nuclear part and lumen, protein-containing complex, nucleoplasm, etc.), as illustrated in Figures 1H,I. Up- and down-regulated RBPs also possessed the molecular functions of nucleic acid binding, RNA binding, catalytic activity acting on RNA, etc. (Figures 1J,K). To probe signaling pathways involved in RBPs with adjusted p < 0.05, KEGG enrichment analyses were implemented. In Figures 1L,M, RNA transport/degradation/polymerase, spliceosome, mRNA surveillance pathway, etc. were remarkably enriched by up- and down-regulated RBPs.
FIGURE 1
Establishment of RBP-based subtypes for heart failure
Consensus clustering analyses were employed for identifying RBP-based subtypes across heart failure specimens in accordance with RBPs with adjusted p < 0.05. Figure 2A illustrated the consensus matrix heatmap at k = 3. We found that heart failure specimens could be clearly categorized as three RBP-based subtypes, namely C1, C2 and C3. Consistent cumulative distribution (CDF) plot showed that when k = 3, CDF reached an approximate maximum (Figure 2B). As depicted in delta area plot, when k = 4, the area under the CDF curve increased only slightly, and thus 3 was an appropriate k value (Figure 2C). Tracking plot was also established for visualizing the sample classification. When k = 3, this classification had relatively high stability (Figure 2D). By reason of the foregoing, three RBP-based subtypes were finally identified across heart failure samples. The accuracy of this classification was verified through PCA plot. In Figure 2E, heart failure samples were clearly classified as three subtypes. Additionally, RBPs with adjusted p < 0.05 presented different expression values across three RBP-based subtypes (Figure 2F). Differentially expressed genes among three RBP-based subtypes were analyzed, and we identified the top 30 up- or down-regulated genes in each subtype compared with others, which were considered as specific marker genes of each subtype (Figures 2G,H). Potential RBPs of up- and down-regulated marker genes were predicted, respectively. As illustrated in Figures 2I,J, no notable differences in number of RBPs of up- and down-regulated marker genes were found across three subtypes.
FIGURE 2
Different molecular mechanisms across RBP-based subtypes
Through GSEA, we dissected the differences in molecular mechanisms between distinct RBP-based subtypes. Compared to C2 subtype, RNA degradation, terpenoid backbone biosynthesis, mismatch repair, oocyte meiosis, proteasome, and ubiquitin mediated proteolysis were remarkably activated in C1 subtype (Figure 3A). Meanwhile, activation of RIG I like receptor signaling pathway, ribosome, JAK-STAT signaling pathway, type II diabetes mellitus, MAPK signaling pathway and aldosterone regulated sodium reabsorption was found in C2 subtype (Figure 3B). Molecular mechanisms between C1 and C3 subtypes were then compared. In Figure 3C, C1 subtype presented the remarkable activation of cytokine-cytokine receptor interaction, cell adhesion molecules CAMS, JAK-STAT signaling pathway and Toll-like receptor signaling pathway than C3 subtype. In comparison to C1 subtype, ubiquitin mediated proteolysis, oxidative phosphorylation, nucleotide excision repair, basal transcription factors, RIG I like receptor signaling pathway, and spliceosome were significantly activated in C3 subtype (Figure 3D). Additionally, we found the significant activation of cytokine-cytokine receptor interaction, JAK-STAT signaling pathway, ECM receptor interactions, leukocyte trans-endothelial migration, cell adhesion molecules CAMS, and focal adhesion in C2 subtype in comparison to C3 subtype (Figure 3E). Meanwhile, ubiquitin mediated proteolysis, nucleotide excision repair, propanoate metabolism, RNA degradation, basal transcription factors, DNA replication, mismatch repair, and oxidative phosphorylation were markedly activated in C3 subtype (Figure 3F). Above data indicated the distinct molecular mechanisms across RBP-based subtypes.
FIGURE 3
Distinct PANoptosis features across RBP-based subtypes
Next, we focused on PANoptosis features in heart failure. Deregulation of PANoptosis (apoptosis, necroptosis and pyroptosis) genes was found in heart failure LV myocardium specimens versus nonfailing controls (Figures 4A–C), indicating that PANoptosis might be linked to heart failure. In addition, PANoptosis features were assessed across three RBP-based subtypes. The widespread heterogeneity in PANoptosis (apoptosis, necroptosis and pyroptosis) genes was observed across RBP-based subtypes (Figures 4D–F).
FIGURE 4
Identification of RBP-based subtype-related genes
WGCNA approach was utilized for determining RBP-based subtype-related genes. Hierarchical clustering analyses demonstrated no outlier specimens (Figure 5A). Soft-thresholding power is an import process of WGCNA. To establish a scale-free co-expression network, soft-thresholding power was set as 9 following scale independence and mean connectivity (Figure 5B). Genes were clustered through dynamic tree cut approach to obtain 16 modules (Figure 5C). Associations between modules and RBP-based subtypes were then evaluated. As a result, blue module presented the strongest correlation to RBP-based subtypes (Figure 5D). Additionally, we found the remarkable correlation between module membership of blue module and gene significance for RBP-based subtypes (Figure 5E). Thus, 1,460 genes in blue module were regarded as RBP-based subtype-related genes. Their biological functions and pathways were then probed. In Figure 5F, RBP-based subtype-related genes were remarkably linked to biosynthetic process. Also, they presented the associations with cellular components such as nuclear part, protein-containing complex, cytosol (Figure 5G). In Figure 5H, they possessed the molecular functions of catalytic activity acting on a protein, sequence-specific DNA binding, and double-stranded DNA binding, etc. RNA transport, mRNA surveillance pathway, nucleotide excision repair, proteasome and DNA replication were remarkably enriched by RBP-based subtype-related genes (Figure 5I). Above data proved their key roles in pathophysiologic processes of heart failure. Through MCODE approach, 31 key RBP-based subtype-related genes were selected, comprising KRR1, DNTTIP2, NGDN, DDX52, RPF1, FTSJ3, RRS1, GTPBP4, RIOK2, DDX5, MPHOSPH10, PAK1IP1, NOC3L, BRIX1, FCF1, DHX15, RRP7A, EBNA1BP2, WDR3, LSG1, DDX10, POLR1D, GNL2, DDX51, RSL24D1, MAK16, GRWD1, RRP15, UTP3, BCCIP, RSL1D1 (Figure 5J). Most key RBP-based subtype-related genes presented the down-regulation in failing than nonfailing control LV myocardium specimens (Figure 5K).
FIGURE 5
Identification of characteristic genes for heart failure via machine learning analyses
Two machine learning approaches LASSO and SVM-RPE were employed for selecting characteristic genes among RBP-based subtype-related genes. 17 and 10 characteristic genes were separately selected by LASSO (Figures 6A,B) and SVM-RPE (Figure 6C) methods. After intersection, ten characteristic genes were finally determined, including DDX52, DHX15, EBNA1BP2, FCF1, GNL2, GRWD1, LSG1, POLR1D, RRS1, and RSL24D1 (Figure 6D). C3 subtype presented the highest expressions of above characteristic genes, followed by C1 and C2 (Figure 6E). To assess the predictive efficacy of characteristic genes, ROC curves were plotted. As illustrated in Figures 6F–O, the AUC values (95%CI) of DDX52, DHX15, EBNA1BP2, FCF1, GNL2, GRWD1, LSG1, POLR1D, RRS1, and RSL24D1 were 0.68 (0.73–0.63), 0.67 (0.72–0.62), 0.64 (0.69–0.58), 0.57 (0.63–0.52), 0.64 (0.70–0.59), 0.70 (0.75–0.66), 0.68 (0.73–0.63), 0.60 (0.66–0.55), 0.73 (0.78–0.67), 0.56 (0.62–0.51), proving the excellent performance in diagnosing heart failure.
FIGURE 6
Establishment of a characteristic gene-based nomogram for heart failure
To facilitate the clinical performance of characteristic genes, a nomogram was established for heart failure (Figure 7A). As illustrated in calibration curve, the nomogram-predicted risk probabilities were close to the actual probabilities of heart failure (Figure 7B). Decision curve analyses demonstrated that the nomogram possessed the preferred prediction efficacy, with the higher net benefit (Figure 7C). Clinical impact curves were drawn for evaluating clinical applicability of the risk predictive nomogram. As illustrated in Figure 7D, the nomogram showed the superior overall net benefit within the wide and practical ranges of threshold probabilities and influenced patients’ outcome, indicating that the nomogram possessed excellent predictive performance. Above data proved that the nomogram was clinically useful. Moreover, the AUC value (95%CI) of the nomogram was 0.84 (0.88–0.80) (Figure 7E), which was higher than any one of characteristic genes, demonstrating that the predictive efficacy of the nomogram was better compared with a single characteristic gene.
FIGURE 7
Landscape of immune cells and PANoptosis features in heart failure
CIBERSORT was employed for estimating the abundance of 24 immune cell types. Firstly, the abundance of immune cell types was compared between human failing and nonfailing control LV myocardium specimens. As illustrated in Figures 8A,B, failing myocardium tissues presented the enhanced abundance of B cell naïve, T cells CD8, T cells CD4 naïve, T cells gamma delta, NK cells resting/activated, macrophages M0, dendritic cells resting/activated, and fibroblasts. Meanwhile, the reduced abundance of B cells memory, T cells CD4 memory activated, macrophages M2, eosinophils, endothelial cells was found in failing myocardium. Additionally, the positive interactions across immune cell types were found, as illustrated in Figure 8C. We also assessed the differences in immune cell types across three RBP-based subtypes. Generally, C2 had the highest abundance of most immune cells, followed by C1 and C3 (Figure 8D). Figure 8E depicted the associations between characteristic genes and immune cell infiltration. Most characteristic genes were negatively linked to the abundance of immune cells, but GRWD1 presented the positive interactions with most immune cell types. In addition, characteristic genes exhibited notable associations with PANoptosis (apoptosis, necroptosis and pyroptosis) genes (Figures 8F–H).
FIGURE 8
External verification of characteristic genes in heart failure
Characteristic genes in heart failure were externally verified in independent datasets. In Figure 9A, DDX52, RRS1, FCF1, DHX15, POLR1D, GNL2, RSL24D1, and EBNA1BP2 presented the low expressions in failing than nonfailing control heart. Inversely, LSG1, and GRWD1 expressions were up-regulated in failing compared with nonfailing control heart in the GSE76701 dataset. The abnormal expression of characteristic genes between human failing and nonfailing control LV myocardium tissues was confirmed in the GSE55296 dataset (Supplementary Figure S1). ROC curves were conducted for evaluating the diagnostic efficacy of above characteristic genes in heart failure in the GSE76701 dataset. The AUC values (95%CI) of DDX52, DHX15, EBNA1BP2, FCF1, GNL2, GRWD1, LSG1, POLR1D, RRS1, and RSL24D1 were 0.88 (1.00–0.59), 0.94 (1.00–0.76), 0.63 (1.00–0.14), 0.75 (1.00–0.35), 1.00 (1.00–1.00), 0.63 (1.00–0.14), 0.81 (1.00–0.43), 0.88 (1.00–0.59), 0.69 (1.00–0.25), and 0.75 (1.00–0.35), as illustrated in Figures 9B–K. However, no significant differences in characteristic genes were observed between HFpEF and HFrEF heart tissues in the GSE86569 dataset (Supplementary Figure S2). In addition, the GSE3585 dataset was adopted to validate the diagnostic efficacy of the characteristic genes. The excellent diagnostic performance of each characteristic gene was proven, as shown in Supplementary Figures S3A–H. Above evidence confirmed that characteristic genes enabled to excellently diagnose heart failure.
FIGURE 9
Prediction of potential therapeutic compounds of heart failure
Based on heart failure-specific RBPs, CMap analysis was adopted to screen potential compounds for the treatment of heart failure with p < 0.05. In accordance with MoA analysis, mebendazole, NPI-2358, vindesine, vincristine, flubendazole, vinorelbine, nocodazole, and ABT-751 shared tubulin inhibitor (Figure 10). GSK-3-inhibitor-IX, SB-415286, and SB-216763 shared glycogen synthase kinase inhibitor. Roscovitine and kenpaullone shared CDK inhibitor. GSK-3-inhibitor-II and PKCbeta-inhibitor shared PKC inhibitor.
FIGURE 10
Discussion
RBPs have been described to be expressed and modulated in a variety of organs especially human heart (). Despite this, little is known concerning the roles of RBPs in heart failure. Thus, our study implemented comprehensive analyses of RBPs in heart failure, and determined RBP-based subtypes, and RBP-based subtype-related characteristic genes, unveiling the crucial functions of RBPs in heart failure.
RBPs are crucial effectors of gene expression, and as such their abnormal expressions underlie the origin of heart failure (). On the basis of the merged GSE5406, and GSE57338 expression profiling datasets, we determined five RBPs (EIF1AY, RPS4Y1, DDX3Y, RNASE2, and CSDC2) with adjusted p < 0.05 and |fold-change|>1.5 in heart failure LV myocardium specimens than nonfailing controls, which were regarded as hear failure-specific RBPs. RBPs with adjusted p < 0.05 were closely linked to RNA metabolism processes (RNA/mRNA/peptide/ncRNA metabolic processes, RNA splicing, and translation) as well as pathways (RNA transport, mRNA surveillance pathway, ribosome biogenesis in eukaryotes, aminoacyl-tRNA biosynthesis, RNA degradation, etc.), highlighting the crucial functions of RBPs in controlling gene expression. Evidence has demonstrated that deregulation of RNA metabolism leads to heart failure progression (). On the basis of RBPs with adjusted p < 0.05, three RBP-based subtypes were established, characterized by distinct signaling pathway activities. Additionally, RBP-based subtype-related genes were further determined, which might be modulated by RBPs.
Previous studies have determined heart-specific RBPs (RBM20, RBM24, HuR, etc.) that were not included in our heart failure-specific RBPs. For instance, suppressing RBM20 activity may improve diastolic dysfunction and cardiac atrophy (). RBM24 loss destroys global alternative splicing and contributes to dilated cardiomyopathy (). HuR-induced SCN5A mRNA stability decreases arrhythmic risk in heart failure (Zhou et al., 2018). Thus, our study offered novel heart-specific RBPs. More experiments are awaited to validate the biological functions of heart failure.
LASSO is a regression analysis approach that utilizes regularization for improving the predictive accuracy (Xing et al., 2022). SVM-RFE is a reliable feature selection approach that determines the optimal variables through removing the feature vectors produced by SVM (Zhao et al., 2020). Through integrating two machine learning approaches, ten characteristic genes were eventually determined, comprising DDX52, DHX15, EBNA1BP2, FCF1, GNL2, GRWD1, LSG1, POLR1D, RRS1, and RSL24D1. All of them accurately predicted the risk of heart failure. Further, a characteristic gene-based nomogram was established, which was capable of accurately predicting heart failure risk, with the excellent clinical usability. DDX52 is a type of DEAD/H box RNA helicase, and its suppression exerts an anti-tumor effect (Yu et al., 2021). The DEAH-box RNA helicase DHX15 has been identified as a potential gene for pathological cardiac hypertrophy triggered by excessive exercise (Zhou et al., 2020) and pulmonary arterial hypertension (Wang et al., 2021). EBNA1BP2 functions as a dynamic scaffold for ribosome biogenesis (). FCF1 is a potential marker of circulating breast cancer cells for detecting metastasis (). The nucleolar GTP-binding protein GNL2 is essential for retinal neurogenesis in developing zebrafish (Paridaen et al., 2011). Cdt1-binding protein GRWD1 acts as a histone-binding protein, which triggers MCM loading via influencing chromatin architecture (Sugimoto et al., 2015). LSG1 is a family member of essential GTPases, in relation to the evolution of compartmentalization (Reynaud et al., 2005). POLR1D is a component of RNA polymerase I and RNA polymerase III complexes, mediating the synthesis of ribosomal RNA precursor and small RNA (Sanchez et al., 2020). RRS1 is a key factor of 5 S rRNA binding activity (). RSL24D1 participates in the biogenesis of the 60 S ribosomal subunit (Ni et al., 2022).
Heart failure is typically linked to cardiac remodeling, and inflammatory response plays a crucial role. During cardiac inflammation, immune cells invade the cardiac tissue as well as modulate tissue-damaging response (). In the present study, failing myocardium tissues exhibited the enhanced abundance of B cell naïve, T cells CD8, T cells CD4 naïve, T cells gamma delta, NK cells resting/activated, macrophages M0, dendritic cells resting/activated, and fibroblasts. Additionally, the decreased abundance of B cells memory, T cells CD4 memory activated, macrophages M2, eosinophils, endothelial cells was observed in failing myocardium. For example, CD8+ effector T cells may prevent cardioprotective macrophage differentiation in early heart failure (). Posttranscriptional control of mRNA modulates inflammatory and immune responses. Several RBPs have been extensively explored, and bind target mRNAs to enhance or dampen above activities (). RBP-based C2 subtype presented the highest abundance of most immune cells, followed by C1 and C3. In addition, there was the extensive heterogeneity in PANoptosis traits across three RBP-based subtypes. Most characteristic genes presented negative correlations to the abundance of immune cells in heart failure, but GRWD1 was positively linked to most immune cell types, indicating their functions in mediating cardiac inflammation. Among them, evidence demonstrates that DHX15 may sense double-stranded RNA in myeloid dendritic cells to activate the immune response to RNA (). Co-expression network analyses have determined DHX15 RNA helicase as a regulator of B cells (). DHX15 is a crucial regulator of natural killer-cell homeostasis and function (Wang et al., 2022). Additionally, characteristic genes exhibited remarkable interactions to PANoptosis features across heart failure. More experiments are required for verifying their regulatory functions in inflammatory and immune responses as well as PANoptosis in heart failure.
Conclusion
Collectively, our findings provided an overview of RBPs involved in heart failure. Three RBP-based subtypes as well as ten relevant characteristic genes were determined for heart failure, elucidating the critical roles of RBPs in pathophysiological process (especially immunity and PANoptosis) of heart failure as well as offering reliable targets for diagnosing heart failure risk. Despite this, in-depth research is required for verifying the effectiveness of RBP-based subtypes and characteristic genes in diagnostic utility of heart failure.
Statements
Data availability statement
The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding authors.
Author contributions
PC, ZW and WZ conceived and designed the study. JL, XZ and PR conducted most of the experiments and data analysis, and wrote the manuscript. YW and YW participated in collecting data and helped to draft the manuscript. All authors reviewed and approved the manuscript.
Funding
This research was supported by Natural Science Foundation of Xinjiang Uygur Autonomous Region (2020D01C088), Fund Project the People’s Hospital of Xinjiang Uygur Autonomous Region (20200109).
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher’s note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
Supplementary material
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fgene.2022.1004163/full#supplementary-material
Abbreviations
LVEF: left ventricular ejection fraction; RBPs: RNA binding proteins; GEO: Gene Expression Omnibus; LV: left ventricular; GO: Gene Ontology; KEGG: Kyoto Encyclopedia of Genes and Genomes; PCA: principal component analyses; GSEA: Gene set enrichment analyses; WGCNA: weighted gene co-expression network analyses; TOM: topological overlap matrix; PPI: protein-protein interaction; STRING: Search Tool for the Retrieval of Interacting Genes; LASSO: least absolute shrinkage and selection operator regression; SVM-RFE: support vector machine recursive feature elimination; ROC: receiver operator characteristic; AUC: area under the curve; CMap: Connectivity Map.
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Summary
Keywords
heart failure, RNA binding protein, subtype, characteristic gene, nomogram, immune cells, PANoptosis
Citation
Li J, Zhang X, Ren P, Wu Y, Wang Y, Zhou W, Wang Z and Chao P (2022) Landscape of RNA-binding proteins in diagnostic utility, immune cell infiltration and PANoptosis features of heart failure. Front. Genet. 13:1004163. doi: 10.3389/fgene.2022.1004163
Received
26 July 2022
Accepted
27 September 2022
Published
14 October 2022
Volume
13 - 2022
Edited by
Xing Niu, China Medical University, China
Updates
Copyright
© 2022 Li, Zhang, Ren, Wu, Wang, Zhou, Wang and Chao.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Wenzheng Zhou, 1975255404@qq.com; Zhao Wang, xjzzqwz@163.com; Peng Chao, cp427701@163.com
† These authors have contributed equally to this work and share first authorship
This article was submitted to RNA, a section of the journal Frontiers in Genetics
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