Epigenetic Regulation of Cardiomyocyte Maturation by Arginine Methyltransferase CARM1.

BACKGROUND: During the neonatal stage, the cardiomyocyte undergoes a constellation of molecular, cytoarchitectural, and functional changes known collectively as cardiomyocyte maturation to increase myocardial contractility and cardiac output. Despite the importance of cardiomyocyte maturation, the molecular mechanisms governing this critical process remain largely unexplored. METHODS: We leveraged an in vivo mosaic knockout system to characterize the role of Carm1, the founding member of protein arginine methyltransferase, in cardiomyocyte maturation. Using a battery of assays, including immunohistochemistry, immuno-electron microscopy imaging, and action potential recording, we assessed the effect of loss of Carm1 function on cardiomyocyte cell growth, myofibril expansion, T-tubule formation, and electrophysiological maturation. Genome-wide transcriptome profiling, H3R17me2a chromatin immunoprecipitation followed by sequencing, and assay for transposase-accessible chromatin with high-throughput sequencing were used to investigate the mechanisms by which CARM1 (coactivator-associated arginine methyltransferase 1) regulates cardiomyocyte maturation. Finally, we interrogated the human syntenic region to the H3R17me2a chromatin immunoprecipitation followed by sequencing peaks for single-nucleotide polymorphisms associated with human heart diseases. RESULTS: We report that mosaic ablation of Carm1 disrupts multiple aspects of cardiomyocyte maturation cell autonomously, leading to reduced cardiomyocyte size and sarcomere thickness, severe loss and disorganization of T tubules, and compromised electrophysiological maturation. Genomics study demonstrates that CARM1 directly activates genes that underlie cardiomyocyte cytoarchitectural and electrophysiological maturation. Moreover, our study reveals significant enrichment of human heart disease-associated single-nucleotide polymorphisms in the human genomic region syntenic to the H3R17me2a chromatin immunoprecipitation followed by sequencing peaks. CONCLUSIONS: This study establishes a critical and multifaceted role for CARM1 in regulating cardiomyocyte maturation and demonstrates that deregulation of CARM1-dependent cardiomyocyte maturation gene expression may contribute to human heart diseases.

Direct cardiac reprogramming comes of age: Recent advance and remaining challenges.

The adult human heart has limited regenerative capacity. As such, the massive cardiomyocyte loss due to myocardial infarction leads to scar formation and adverse cardiac remodeling, which ultimately results in chronic heart failure. Direct cardiac reprogramming that converts cardiac fibroblast into functional cardiomyocyte-like cells (also called iCMs) holds great promise for heart regeneration. Cardiac reprogramming has been achieved both in vitro and in vivo by using a variety of cocktails that comprise transcription factors, microRNAs, or small molecules. During the past several years, great progress has been made in improving reprogramming efficiency and understanding the underlying molecular mechanisms. Here, we summarize the direct cardiac reprogramming methods, review the current advances in understanding the molecular mechanisms of cardiac reprogramming, and highlight the novel insights gained from single-cell omics studies. Finally, we discuss the remaining challenges and future directions for the field.

Diverse functions of TRIB3 in cancers and its potential as a therapeutic target.

Currently, cancer is the second leading cause of death worldwide, and potential targeted drugs and molecular pathways for cancer development and progression have been a hot research topic worldwide. In recent years, the importance of kinase superfamily in diseases has been well demonstrated by studies on various molecular mechanisms of kinases and successful application of their inhibitors in diseases. Pseudokinases are members of kinase superfamily, which have been increasingly documented to play a crucial role in cancers year after year. As a member of pseudokinases, tribbles homolog 3 (TRIB3) also exerts diverse functions in different cancers through different interacting proteins and molecular pathways, especially in tumor immunity, stemness, drug resistance, metabolism and autophagy. In addition, peptide drugs targeting TRIB3 have high specificity in preclinical studies, which shows great promise for TRIB3 application in diseases including cancers. In this review, we dissect diverse functions played by TRIB3 in different cancers, describing the underlying mechanisms in detail. Notably, inhibitors and agonists currently available for TRIB3 are discussed, indicating potential for TRIB3 as a therapeutic target.

Biomolecular Condensates Decipher Molecular Codes of Cell Fate: From Biophysical Fundamentals to Therapeutic Practices.

Cell fate is precisely modulated by complex but well-tuned molecular signaling networks, whose spatial and temporal dysregulation commonly leads to hazardous diseases. Biomolecular condensates (BCs), as a newly emerging type of biophysical assemblies, decipher the molecular codes bridging molecular behaviors, signaling axes, and clinical prognosis. Particularly, physical traits of BCs play an important role; however, a panoramic view from this perspective toward clinical practices remains lacking. In this review, we describe the most typical five physical traits of BCs, and comprehensively summarize their roles in molecular signaling axes and corresponding major determinants. Moreover, establishing the recent observed contribution of condensate physics on clinical therapeutics, we illustrate next-generation medical strategies by targeting condensate physics. Finally, the challenges and opportunities for future medical development along with the rapid scientific and technological advances are highlighted.

iSMNN: batch effect correction for single-cell RNA-seq data via iterative supervised mutual nearest neighbor refinement.

Batch effect correction is an essential step in the integrative analysis of multiple single-cell RNA-sequencing (scRNA-seq) data. One state-of-the-art strategy for batch effect correction is via unsupervised or supervised detection of mutual nearest neighbors (MNNs). However, both types of methods only detect MNNs across batches of uncorrected data, where the large batch effects may affect the MNN search. To address this issue, we presented a batch effect correction approach via iterative supervised MNN (iSMNN) refinement across data after correction. Our benchmarking on both simulation and real datasets showed the advantages of the iterative refinement of MNNs on the performance of correction. Compared to popular alternative methods, our iSMNN is able to better mix the cells of the same cell type across batches. In addition, iSMNN can also facilitate the identification of differentially expressed genes (DEGs) that are relevant to the biological function of certain cell types. These results indicated that iSMNN will be a valuable method for integrating multiple scRNA-seq datasets that can facilitate biological and medical studies at single-cell level.

Substrate-selective protein ectodomain shedding by ADAM17 and iRhom2 depends on their juxtamembrane and transmembrane domains.

The metalloprotease ADAM17 (a disintegrin and metalloprotease 17) regulates EGF-receptor and TNFα signaling, thereby not only protecting the skin and intestinal barrier, but also contributing to autoimmunity. ADAM17 can be rapidly activated by many stimuli through its transmembrane domain (TMD), with the seven membrane-spanning inactive Rhomboids (iRhom) 1 and 2 implicated as candidate regulatory partners. However, several alternative models of ADAM17 regulation exist that do not involve the iRhoms, such as regulation through disulfide bond exchange or through interaction with charged phospholipids. Here, we report that a non-activatable mutant of ADAM17 with the TMD of betacellulin (BTC) can be rescued by restoring residues from the ADAM17 TMD, but only in Adam17-/- cells, which contain iRhoms, not in iRhom1/2-/- cells. We also provide the first evidence that the extracellular juxtamembrane domains (JMDs) of ADAM17 and iRhom2 regulate the stimulation and substrate selectivity of ADAM17. Interestingly, a point mutation in the ADAM17 JMD identified in a patient with Tetralogy of Fallot, a serious heart valve defect, affects the substrate selectivity of ADAM17 toward Heparin-binding epidermal growth factor like growth factor (HB-EGF), a crucial regulator of heart valve development in mice. These findings provide new insights into the regulation of ADAM17 through an essential interaction with the TMD1 and JMD1 of iRhom2.

Gender Differences in Low-Molecular-Mass-Induced Acute Lung Inflammation in Mice.

Gender differences in pulmonary inflammation have been well documented. Although low molecular mass hyaluronan (LMMHA) is known to trigger pulmonary lung inflammation, sex differences in susceptibility to LMMHA are still unknown. In this study, we test the hypothesis that mice may display sex-specific differences after LMMHA administration. After LMMHA administration, male mice have higher neutrophil, cytokine, and chemokine counts compared to that of their female counterparts. Additionally, Ovariectomized (OVX) mice show greater LMMHA-induced inflammation compared to that of mice with intact ovaries. Injections of OVX mice with 17ß-estradiol can decrease inflammatory responses in the OVX mice. These results show that ovarian hormones regulate LMMHA induced lung inflammation.

ExpressHeart: Web Portal to Visualize Transcriptome Profiles of Non-Cardiomyocyte Cells.

Unveiling the molecular features in the heart is essential for the study of heart diseases. Non-cardiomyocytes (nonCMs) play critical roles in providing structural and mechanical support to the working myocardium. There is an increasing amount of single-cell RNA-sequencing (scRNA-seq) data characterizing the transcriptomic profiles of nonCM cells. However, no tool allows researchers to easily access the information. Thus, in this study, we develop an open-access web portal, ExpressHeart, to visualize scRNA-seq data of nonCMs from five laboratories encompassing three species. ExpressHeart enables comprehensive visualization of major cell types and subtypes in each study; visualizes gene expression in each cell type/subtype in various ways; and facilitates identifying cell-type-specific and species-specific marker genes. ExpressHeart also provides an interface to directly combine information across datasets, for example, generating lists of high confidence DEGs by taking the intersection across different datasets. Moreover, ExpressHeart performs comparisons across datasets. We show that some homolog genes (e.g., Mmp14 in mice and mmp14b in zebrafish) are expressed in different cell types between mice and zebrafish, suggesting different functions across species. We expect ExpressHeart to serve as a valuable portal for investigators, shedding light on the roles of genes on heart development in nonCM cells.

MicroRNA-155 Participates in Smoke-Inhalation-Induced Acute Lung Injury through Inhibition of SOCS-1.

Smoke inhalation causes acute lung injury (ALI), a severe clinical disease with high mortality. Accumulating evidence indicates that microRNA-155 (miR-155) and suppressor of cytokine signaling 1 (SOCS-1), as mediators of inflammatory response, are involved in the pathogenesis of ALI. In this paper, we explored the proinflammatory mechanism of miR-155 in smoke-inhalation-induced ALI. Our data revealed that smoke inhalation induces miR-155 expression, and miR-155 knockout (KO) significantly ameliorates smoke-inhalation-induced lung injury in mice. Neutrophil infiltration and myeloperoxidase (MPO), macrophage inflammatory protein 2 (MIP-2) and keratinocyte chemoattractant (KC) expressions were decreased in miR-155-/- mice after smoke inhalation as well. Real-time RT-PCR and immunoblotting results showed that SOCS-1 level was remarkably increased in miR-155-/- mice after smoke exposure. Furthermore, the experiments performed in isolated miR-155 KO pulmonary neutrophils demonstrated that the lack of SOCS-1 enhanced inflammatory cytokines (MIP-2 and KC) secretion in response to smoke stimulation. In conclusion, smoke induces increased expression of miR-155, and miR-155 is involved in inflammatory response to smoke-inhalation-induced lung injury by inhibiting the expression of SOCS-1.

Rare mutations of ADAM17 from TOFs induce hypertrophy in human embryonic stem cell-derived cardiomyocytes via HB-EGF signaling.

Tetralogy of Fallot (TOF) is the most common cyanotic form of congenital heart defects (CHDs). The right ventricular hypertrophy is associated with the survival rate of patients with repaired TOF. However, very little is known concerning its genetic etiology. Based on mouse model studies, a disintergrin and metalloprotease 10/17 (ADAM10 and ADAM17) are the key enzymes for the NOTCH and ErbB pathways, which are critical pathways for heart development. Mutations in these two genes have not been previously reported in human TOF patients. In this study, we sequenced ADAM10 and ADAM17 in a Han Chinese CHD cohort comprised of 80 TOF patients, 286 other CHD patients, and 480 matched healthy controls. Three missense variants of ADAM17 were only identified in 80 TOF patients, two of which (Y42D and L659P) are novel and not found in the Exome Aggregation Consortium (ExAC) database. Point mutation knock-in (KI) and ADAM17 knock-out (KO) human embryonic stem cells (hESCs) were generated by CRISPR/Cas9 and programmed to differentiate into cardiomyocytes (CMs). Y42D or L659P KI cells or complete KO cells all developed hypertrophy with disorganized sarcomeres. RNA-seq results showed that phosphatidylinositide 3-kinases/protein kinase B (PI3K/Akt), which is downstream of epidermal growth factor receptor (EGFR) signaling, was affected in both ADAM17 KO and KI hESC-CMs. In vitro experiments showed that these two mutations are loss-of-function mutations in shedding heparin-binding EGF-like growth factor (HB-EGF) but not NOTCH signaling. Our results revealed that CM hypertrophy in TOF could be the result of mutations in ADAM17 which affects HB-EGF/ErbB signaling.

Clinical efficacy and applicability of natural products in the treatment and prevention of radiotherapy-induced oral mucositis: A systematic review.

The aim of this systematic review was to describe the efficacy and acceptability of natural products in the management of oral mucositis caused by radiation. From the day it started to August 7, 2023, a thorough search for randomized controlled trials (RCTs) was carried out among seven databases: the Web of Science, PubMed, Embase, OVID, Scopus, the Cochrane Library and the CINAHL database. Only English-language articles were identified during the search. Using the revised Cochrane risk-of-bias tool, version 2, two researchers screened the articles, collected information on study characteristics, and appraised risks of bias. The data were analyzed and descriptively presented with a narrative synthesis methodology involving the Synthesis Without Meta-Analysis (SWiM) reporting element applied in detail. The PROSPERO registration number of this study is CRD42023476932. Thirty-six clinical trials were included in the study; the included studies included a variety of 20 types of natural products. Honey and Curcuma longa were the most commonly assessed natural products. A total of 2,400 participants reported taking part in therapy with natural products for oral mucositis. Natural products demonstrated substantial efficacy in terms of influencing intensity, incidence, pain score, quality of life, and symptoms such as xerostomia and dysphagia. Except for manuka honey, most natural products were well accepted. Regarding the clinical trials' risk of bias, 2 clinical trials (5.56%) had a high risk of bias, 17 studies (47.2%) had a low risk of bias, and 17 studies (47.2%) were rated with "some concern." Natural remedies work well as alternate treatments for managing oral mucositis caused by radiation therapy. However, additional clinical trials are still needed. The safety of these conventional medications as well as their effectiveness and safety when used in combination with other conventional or naturopathic therapies should be fully examined.

Direct conversion of cardiac fibroblasts into endothelial-like cells using Sox17 and Erg.

Endothelial cells are a heterogeneous population with various organ-specific and conserved functions that are critical to organ development, function, and regeneration. Here we report a Sox17-Erg direct reprogramming approach that uses cardiac fibroblasts to create differentiated endothelial cells that demonstrate endothelial-like molecular and physiological functions in vitro and in vivo. Injection of these induced endothelial cells into myocardial infarct sites after injury results in improved vascular perfusion of the scar region. Furthermore, we use genomic analyses to illustrate that Sox17-Erg reprogramming instructs cardiac fibroblasts toward an arterial-like identity. This results in a more efficient direct conversion of fibroblasts into endothelial-like cells when compared to traditional Etv2-based reprogramming. Overall, this Sox17-Erg direct reprogramming strategy offers a robust tool to generate endothelial cells both in vitro and in vivo, and has the potential to be used in repairing injured tissue.

The Circadian Clock Component RORA Increases Immunosurveillance in Melanoma by Inhibiting PD-L1 Expression.

Circadian clock perturbation frequently occurs in cancer and facilitates tumor progression by regulating malignant growth and shaping the immune microenvironment. Emerging evidence has indicated that clock genes are disrupted in melanoma and linked to immune escape. Herein, we found that the expression of retinoic acid receptor-related orphan receptor-α (RORA) is downregulated in melanoma patients and that patients with higher RORA expression have a better prognosis after immunotherapy. Additionally, RORA was significantly positively correlated with T-cell infiltration and recruitment. Overexpression or activation of RORA stimulated cytotoxic T-cell-mediated antitumor responses. RORA bound to the CD274 promoter and formed an inhibitory complex with HDAC3 to suppress PD-L1 expression. In contrast, the DEAD-box helicase family member DDX3X competed with HDAC3 for binding to RORA, and DDX3X overexpression promoted RORA release from the suppressive complex and thereby increased PD-L1 expression to generate an inhibitory immune environment. The combination of a RORA agonist with an anti-CTLA4 antibody synergistically increased T-cell antitumor immunity in vivo. A score based on the combined expression of HDAC3, DDX3X, and RORA correlated with immunotherapy response in melanoma patients. Together, this study elucidates a mechanism of clock component-regulated antitumor immunity, which will help inform the use of immunotherapy and lead to improved outcomes for melanoma patients receiving combined therapeutic treatments. Significance: RORA forms a corepressor complex to inhibit PD-L1 expression and activate antitumor T-cell responses, indicating that RORA is a potential target and predictive biomarker to improve immunotherapy response in melanoma patients.

A paired dataset of T1- and T2-weighted MRI at 3 Tesla and 7 Tesla.

Brain magnetic resonance imaging (MRI) provides detailed soft tissue contrasts that are critical for disease diagnosis and neuroscience research. Higher MRI resolution typically comes at the cost of signal-to-noise ratio (SNR) and tissue contrast, particularly for more common 3 Tesla (3T) MRI scanners. At ultra-high magnetic field strength, 7 Tesla (7T) MRI allows for higher resolution with greater tissue contrast and SNR. However, the prohibitively high costs of 7T MRI scanners deter their widespread adoption in clinical and research centers. To obtain higher-quality images without 7T MRI scanners, algorithms that can synthesize 7T MR images from 3T MR images are under active development. Here, we make available a dataset of paired T1-weighted and T2-weighted MR images at 3T and 7T of 10 healthy subjects to facilitate the development and evaluation of 3T-to-7T MR image synthesis models. The quality of the dataset is assessed using image quality metrics implemented in MRIQC.

Luteolin inhibits the TGF-ß signaling pathway to overcome bortezomib resistance in multiple myeloma.

Multiple myeloma (MM) is an incurable condition and the second most common hematological malignancy. Over the past few years, there has been progress in the treatment of MM, but most patients still relapse. Multiple myeloma stem-like cells (MMSCs) are believed to be the main reason for drug resistance and eventual relapse. Currently, there are not enough therapeutic agents that have been identified for eradication of MMSCs, and thus, identification of the same may alleviate the issue of relapse in patients. In the present study, we showed that luteolin (LUT), a natural compound obtained from different plants, such as vegetables, medicinal herbs, and fruits, effectively inhibits the proliferation of MM cells and overcomes bortezomib (BTZ) resistance in them in vitro and in vivo, mainly by decreasing the proportion of ALDH1+ cells. Furthermore, RNA sequencing after LUT treatment of MM cell lines and an MM xenograft mouse model revealed that the effects of the compound are mediated through inhibition of transforming growth factor-ß signaling. Similarly, we found that LUT also significantly reduced the proportion of ALDH1+ cells in primary CD138+ plasma cells. In addition, LUT could overcome the BTZ treatment-induced increase in the proportion of ALDH1+ cells, and the combination of LUT and BTZ had a synergistic effect against myeloma cells. Collectively, our findings suggested that LUT is a promising agent that manifests MMSCs to overcome BTZ resistance, alone or in combination with BTZ, and thus, is a potential therapeutic drug for the treatment of MM.

Anti-BCMA surface engineered biomimetic photothermal nanomissile enhances multiple myeloma cell apoptosis and overcomes the disturbance of NF-κB signaling in vivo.

Conventional chemotherapy for multiple myeloma (MM) faces the challenges of a low complete remission rate and transformation to recurrence/refractory. The current MM first-line clinical drug Bortezomib (BTZ) faces the problem of enhanced tolerance and nonnegligible side effects. B cell maturation antigen (BCMA), for its important engagement in tumor signaling pathways and novel therapy technologies such as Chimeric antigen receptor T-Cell immunotherapy (CAR-T) and Antibody Drug Conjugate (ADC), has been identified as an ideal target and attracted attention in anti-MM therapy. Emerging nanotechnology provided feasible methods for drug delivery and new therapeutic strategies such as photothermal therapy (PTT). Herein, we developed a BCMA-Targeting biomimetic photothermal nanomissile BTZ@BPQDs@EM @anti-BCMA (BBE@anti-BCMA) by integration of BTZ, black phosphorus quantum dots (BPQDs), Erythrocyte membrane (EM) and BCMA antibody (anti-BCMA). We hypothesized that this engineered nanomissile could attack tumor cells in triple ways and achieve effective treatment of MM. Consequently, the intrinsic biomimetic nature of EM and the active targeting property of anti-BCMA enhanced the accumulation of therapeutic agents in the tumor site. Besides, owing to the decrease in BCMA abundance, the potential apoptosis-inducing ability was revealed. With the support of BPQDs' photothermal effect, Cleaved-Caspase-3 and Bax signal increased significantly, and the expression of Bcl-2 was inhibited. Furthermore, the synergistic photothermal/chemo therapy can effectively inhibit tumor growth and reverse the disorder of NF-κB in vivo. Importantly, this biomimetic nanodrug delivery system and antibody induced synergistic therapeutic strategy efficiently killed MM cells with ignorable systemic toxicity, which is a promising method for the future anticancer treatment of hematological malignancies in clinics.

Hippo pathway-manipulating neutrophil-mimic hybrid nanoparticles for cardiac ischemic injury via modulation of local immunity and cardiac regeneration.

The promise of regeneration therapy for restoration of damaged myocardium after cardiac ischemic injury relies on targeted delivery of proliferative molecules into cardiomyocytes whose healing benefits are still limited owing to severe immune microenvironment due to local high concentration of proinflammatory cytokines. Optimal therapeutic strategies are therefore in urgent need to both modulate local immunity and deliver proliferative molecules. Here, we addressed this unmet need by developing neutrophil-mimic nanoparticles NM@miR, fabricated by coating hybrid neutrophil membranes with artificial lipids onto mesoporous silica nanoparticles (MSNs) loaded with microRNA-10b. The hybrid membrane could endow nanoparticles with strong capacity to migrate into inflammatory sites and neutralize proinflammatory cytokines and increase the delivery efficiency of microRNA-10b into adult mammalian cardiomyocytes (CMs) by fusing with cell membranes and leading to the release of MSNs-miR into cytosol. Upon NM@miR administration, this nanoparticle could home to the injured myocardium, restore the local immunity, and efficiently deliver microRNA-10b to cardiomyocytes, which could reduce the activation of Hippo-YAP pathway mediated by excessive cytokines and exert the best proliferative effect of miR-10b. This combination therapy could finally improve cardiac function and mitigate ventricular remodeling. Consequently, this work offers a combination strategy of immunity modulation and proliferative molecule delivery to boost cardiac regeneration after injury.

Translational landscape of direct cardiac reprogramming reveals a role of Ybx1 in repressing cardiac fate acquisition.

Direct reprogramming of fibroblasts into induced cardiomyocytes holds great promise for heart regeneration. Although considerable progress has been made in understanding the transcriptional and epigenetic mechanisms of iCM reprogramming, its translational regulation remains largely unexplored. Here, we characterized the translational landscape of iCM reprogramming through integrative ribosome and transcriptomic profiling, and found extensive translatome repatterning during this process. Loss of function screening for translational regulators uncovered Ybx1 as a critical barrier to iCM induction. In a mouse model of myocardial infarction, removing Ybx1 enhanced in vivo reprogramming, resulting in improved heart function and reduced scar size. Mechanistically, Ybx1 depletion de-repressed the translation of its direct targets SRF and Baf60c, both of which mediated the effect of Ybx1 depletion on iCM generation. Furthermore, removal of Ybx1 allowed single factor Tbx5-mediated iCM conversion. In summary, this study revealed a new layer of regulatory mechanism that controls cardiac reprogramming at the translational level.

Cross-lineage potential of Ascl1 uncovered by comparing diverse reprogramming regulatomes.

Direct reprogramming has revolutionized the fields of stem cell biology and regenerative medicine. However, the common mechanisms governing how reprogramming cells undergo transcriptome and epigenome remodeling (i.e., regulatome remodeling) have not been investigated. Here, by characterizing early changes in the regulatome of three different types of direct reprogramming, we identify lineage-specific features as well as common regulatory transcription factors. Of particular interest, we discover that the neuronal factor Ascl1 possesses cross-lineage potential; together with Mef2c, it drives efficient cardiac reprogramming toward a mature and induced cardiomyocyte phenotype. Through ChIP-seq and RNA-seq, we find that MEF2C drives the shift in ASCL1 binding away from neuronal genes toward cardiac genes, guiding their co-operative epigenetic and transcription activities. Together, these findings demonstrate the existence of common regulators of different direct reprogramming and argue against the premise that transcription factors possess only lineage-specific capabilities for altering cell fate - the basic premise used to develop direct reprogramming approaches.

Single-cell dual-omics reveals the transcriptomic and epigenomic diversity of cardiac non-myocytes.

AIMS: The precise cellular identity and molecular features of non-myocytes (non-CMs) in a mammalian heart at a single-cell level remain elusive. Depiction of epigenetic landscape with transcriptomic signatures using the latest single-cell multi-omics has the potential to unravel the molecular programs underlying the cellular diversity of cardiac non-myocytes. Here, we characterized the molecular and cellular features of cardiac non-CM populations in the adult murine heart at the single-cell level. METHODS AND RESULTS: Through single-cell dual omics analysis, we mapped the epigenetic landscapes, characterized the transcriptomic profiles and delineated the molecular signatures of cardiac non-CMs in the adult murine heart. Distinct cis-regulatory elements and trans-acting factors for the individual major non-CM cell types (endothelial cells, fibroblast, pericytes, and immune cells) were identified. In particular, unbiased sub-clustering and functional annotation of cardiac fibroblasts (FBs) revealed extensive FB heterogeneity and identified FB sub-types with functional states related to the cellular response to stimuli, cytoskeleton organization, and immune regulation, respectively. We further explored the function of marker genes Hsd11b1 and Gfpt2 that label major FB subpopulations and determined the distribution of Hsd11b1+ and Gfp2+ FBs in murine healthy and diseased hearts. CONCLUSIONS: In summary, we characterized the non-CM cellular identity at the transcriptome and epigenome levels using single-cell omics approaches and discovered previously unrecognized cardiac fibroblast subpopulations with unique functional states.