Integrins and integrin-related proteins in cardiac fibrosis

Nicotinamide riboside kinase 2: A unique target for skeletal muscle and cardiometabolic diseases

Myopathy leads to skeletal and cardiac muscle degeneration which is a major cause of physical disability and heart failure. Despite the therapeutic advancement the prevalence of particularly cardiac diseases is rising at an alarming rate and novel therapeutic targets are required. Nicotinamide riboside kinase-2 (NRK-2 or NMRK2) is a muscle-specific β1-integrin binding protein abundantly expressed in the skeletal muscle while only a trace amount is detected in the healthy cardiac muscle. The level in cardiac tissue is profoundly upregulated under pathogenic conditions such as ischemia and hypertension. NRK-2 was initially identified to regulate myoblast differentiation and to enhance the levels of NAD+, an important coenzyme that potentiates cellular energy production and stress resilience. Recent advancement has shown that NRK-2 critically regulates numerous cellular and molecular processes under pathogenic conditions to modulate the disease severity. Therefore, given its restricted expression in the cardiac and skeletal muscle, NRK-2 may serve as a unique therapeutic target. In this review, we provided a comprehensive overview of the diverse roles of NRK-2 played in different cardiac and muscular diseases and discussed the underlying molecular mechanisms in detail. Moreover, this review precisely examined how NRK-2 regulates metabolism in cardiac muscle, and how dysfunctional NRK-2 is associated with energetic deficit and impaired muscle function, manifesting various cardiac and skeletal muscle disease conditions.

Knockdown of ANO1 decreases TGF-β- and IL-6-induced adhesion and migration of cardiac fibroblasts by inhibiting the expression of integrin and focal adhesion kinase

Ischemic cardiac injury triggers a significant inflammatory response, activating and mobilizing cardiac fibroblasts (CFs), which ultimately contributes to myocardial fibrosis. In this study, we investigated the role of ANO1, a calcium-activated chloride channel (CaCC) protein, in regulating CFs migration and adhesion under inflammatory conditions. Our results demonstrated that ANO1 knockdown significantly attenuated TGF-β- and IL-6-induced adhesion and migration of CFs. This inhibitory effect was mediated through the downregulation of integrin expression and reduced activation of focal adhesion kinase (FAK), key components in cellular adhesion and motility pathways. This study provides new insights into the mechanisms underlying CFs migration and adhesion, highlighting the potential of ANO1 as a therapeutic target for mitigating adverse fibrotic remodeling following myocardial infarction.

Epigenetic Regulation in Myocardial Fibroblasts and Its Impact on Cardiovascular Diseases

Myocardial fibroblasts play a crucial role in heart structure and function. In recent years, significant progress has been made in understanding the epigenetic regulation of myocardial fibroblasts, which is essential for cardiac development, homeostasis, and disease progression. In healthy hearts, cardiac fibroblasts (CFs) play a crucial role in synthesizing the extracellular matrix (ECM) when in a dormant state. However, under pathological and environmental stress, CFs transform into activated fibroblasts known as myofibroblasts. These myofibroblasts produce an excess of ECM, which promotes cardiac fibrosis. Although multiple molecular mechanisms are associated with CF activation and myocardial dysfunction, emerging evidence highlights the significant involvement of epigenetic regulation in this process. Epigenetics refers to the heritable changes in gene expression that occur without altering the DNA sequence. These mechanisms have emerged as key regulators of myocardial fibroblast function. This review focuses on recent advancements in the understanding of the role of epigenetic regulation and emphasizes the impact of epigenetic modifications on CF activation. Furthermore, we present perspectives and prospects for future research on epigenetic modifications and their implications for myocardial fibroblasts.

Peritoneal infection after colorectal cancer surgery induces substantial alterations in postoperative protein levels: an exploratory study

PURPOSE

Peritoneal infection, due to anastomotic leakage, after resection for colorectal cancer have been shown to associate with increased cancer recurrence and mortality, as well as cardiovascsular morbidity. Alterations in circulating protein levels could help shed light on the underlying mechanisms, prompting this exploratory study of 64 patients operated for colorectal cancer with anastomosis.

METHODS

Thirty-two cases who suffered a postoperative peritoneal infection were matched with 32 controls who had a complication-free postoperative stay. Proteins in serum samples at their first postoperative visit and at one year after surgery were analysed using proximity extension assays and enzyme-linked immunosorbent assays. Multivariate projection methods, adjusted for multiple testing, were used to compare levels between groups, and enrichment and network analyses were performed.

RESULTS

Seventy-seven proteins, out of 270 tested, were differentially expressed at a median sampling time of 41 days postoperatively. These proteins were all normalised one year after surgery. Many of the differentially expressed top hub proteins have known involvement in cancer progression, survival, invasiveness and metastasis. Over-represented pathways were related to cardiomyopathy, cell-adhesion, extracellular matrix, phosphatidylinositol-3-kinase/Akt (PI3K-Akt) and transforming growth factor beta (TGF-β) signaling.

CONCLUSION

These affected proteins and pathways could provide clues as to why patients with peritoneal infection might suffer increased cancer recurrence, mortality and cardiovascular morbidity.

ITIH4 reversed the effects of thrombin on VSMCs stiffness via JNK and ERK signaling pathway

Vascular smooth muscle cell (VSMCs) is one of the important cell types in artery. VSMCs stiffening may regulate vascular stiffness and contribute to the development of vulnerable plaques. Thrombin, an enzyme in coagulation system, is involved in pathological processes of atherosclerosis. Inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4) plays an important role in regulating inflammation and may have cardiovascular protective effect. Therefore, the elucidation of the mechanisms underlying ITIH4-mediated VSMCs stiffening helps to provide new ideas and potential targets for the diagnosis and treatment of atherosclerosis. In this study, we used specific ITIH4 expression vector and siRNA methods to transfect VSMCs. Our results found that ITIH4 expression increased VSMCs stiffness, meanwhile, ITIH4 siRNA decreased VSMCs stiffness. ITIH4 increased acetylated α-tubulin and inhibited ERK1/2 and JNK, but not P38 MAPK. ERK inhibitor (PD98059) or JNK inhibitor (SP600125) treatment increased acetylated α-tubulin expression and cell stiffness in VSMCs. ITIH4 was downregulated by thrombin treatment, ITIH4 partly reversed the effect of thrombin on acetylated α-tubulin and VSMCs stiffness. These results indicated that ITIH4 regulated acetylated α-tubulin expression in VSMCs and was against the effects of thrombin on VSMCs stiffness. JNK and ERK signaling pathways were proved to participate in this process.

Bone marrow-fibroblast progenitor cell-derived small extracellular vesicles promote cardiac fibrosis via miR-21-5p and integrin subunit αV signalling

Cardiac fibrosis is the hallmark of cardiovascular disease (CVD), which is leading cause of death worldwide. Previously, we have shown that interleukin-10 (IL10) reduces pressure overload (PO)-induced cardiac fibrosis by inhibiting the recruitment of bone marrow fibroblast progenitor cells (FPCs) to the heart. However, the precise mechanism of FPC involvement in cardiac fibrosis remains unclear. Recently, exosomes and small extracellular vesicles (sEVs) have been linked to CVD progression. Thus, we hypothesized that pro-fibrotic miRNAs enriched in sEV-derived from IL10 KO FPCs promote cardiac fibrosis in pressure-overloaded myocardium. Small EVs were isolated from FPCs cultured media and characterized as per MISEV-2018 guidelines. Small EV's miRNA profiling was performed using Qiagen fibrosis-associated miRNA profiler kit. For functional analysis, sEVs were injected in the heart following TAC surgery. Interestingly, TGFβ-treated IL10-KO-FPCs sEV increased profibrotic genes expression in cardiac fibroblasts. The exosomal miRNA profiling identified miR-21a-5p as the key player, and its inhibition with antagomir prevented profibrotic signalling and fibrosis. At mechanistic level, miR-21a-5p binds and stabilizes ITGAV (integrin av) mRNA. Finally, miR-21a-5p-silenced in sEV reduced PO-induced cardiac fibrosis and improved cardiac function. Our study elucidates the mechanism by which inflammatory FPC-derived sEV exacerbate cardiac fibrosis through the miR-21a-5p/ITGAV/Col1α signalling pathway, suggesting miR-21a-5p as a potential therapeutic target for treating hypertrophic cardiac remodelling and heart failure.

Combination of ADAM17 knockdown with eplerenone is more effective than single therapy in ameliorating diabetic cardiomyopathy

Background

The renin-angiotensin-aldosterone system (RAAS) members, especially Ang II and aldosterone, play key roles in the pathogenesis of diabetic cardiomyopathy (DCM). Angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers combined with aldosterone receptor antagonists (mineralocorticoid receptor antagonists) have substantially improved clinical outcomes in patients with DCM. However, the use of the combination has been limited due to its high risk of inducing hyperkalemia.

Methods

Type 1 diabetes was induced in 8-week-old male C57BL/6J mice by intraperitoneal injection of streptozotocin at a dose of 55 mg/kg for 5 consecutive days. Adeno-associated virus 9-mediated short-hairpin RNA (shRNA) was used to knock down the expression of ADAM17 in mice hearts. Eplerenone was administered via gavage at 200 mg/kg daily for 4 weeks. Primary cardiac fibroblasts were exposed to high glucose (HG) in vitro for 24 h to examine the cardiac fibroblasts to myofibroblasts transformation (CMT).

Results

Cardiac collagen deposition and CMT increased in diabetic mice, leading to cardiac fibrosis and dysfunction. In addition, ADAM17 expression and activity increased in the hearts of diabetic mice. ADAM17 inhibition and eplerenone treatment both improved diabetes-induced cardiac fibrosis, cardiac hypertrophy and cardiac dysfunction, ADAM17 deficiency combined with eplerenone further reduced the effects of cardiac fibrosis, cardiac hypertrophy and cardiac dysfunction compared with single therapy in vivo. High-glucose stimulation promotes CMT in vitro and leads to increased ADAM17 expression and activity. ADAM17 knockdown and eplerenone pretreatment can reduce the CMT of fibroblasts that is induced by high glucose levels by inhibiting TGFβ1/Smad3 activation; the combination of the two can further reduce CMT compared with single therapy in vitro.

Conclusion

Our findings indicated that ADAM17 knockout could improve diabetes-induced cardiac dysfunction and remodeling through the inhibition of RAAS overactivation when combined with eplerenone treatment, which reduced TGF-β1/Smad3 pathway activation-mediated CMT. The combined intervention of ADAM17 deficiency and eplerenone therapy provided additional cardiac protection compared with a single therapy alone without disturbing potassium level. Therefore, the combination of ADAM17 inhibition and eplerenone is a potential therapeutic strategy for human DCM.

Elevated ITGA1 levels in type 2 diabetes: implications for cardiac function impairment

AIMS/HYPOTHESIS

Type 2 diabetes mellitus is known to contribute to the development of heart failure with preserved ejection fraction (HFpEF). However, identifying HFpEF in individuals with type 2 diabetes early on is often challenging due to a limited array of biomarkers. This study aims to investigate specific biomarkers associated with the progression of HFpEF in individuals with type 2 diabetes, for the purpose of enabling early detection and more effective management strategies.

METHODS

Blood samples were collected from individuals with type 2 diabetes, both with and without HFpEF, for proteomic analysis. Plasma integrin α1 (ITGA1) levels were measured and compared between the two groups. Participants were further categorised based on ITGA1 levels and underwent detailed transthoracic echocardiography at baseline and during a median follow-up period of 30 months. Multivariable linear and Cox regression analyses were conducted separately to assess the associations between plasma ITGA1 levels and changes in echocardiography indicators and re-hospitalisation risk. Additionally, proteomic data for the individuals' left ventricles, from ProteomeXchange database, were analysed to uncover mechanisms underlying the change in ITGA1 levels in HFpEF.

RESULTS

Individuals with type 2 diabetes and HFpEF showed significantly higher plasma ITGA1 levels than the individuals with type 2 diabetes without HFpEF. These elevated ITGA1 levels were associated with left ventricular remodelling and impaired diastolic function. Furthermore, during a median follow-up of 30 months, multivariable analysis revealed that elevated ITGA1 levels independently correlated with deterioration of both diastolic and systolic cardiac functions. Additionally, higher baseline plasma ITGA1 levels independently predicted re-hospitalisation risk (HR 2.331 [95% CI 1.387, 3.917], p=0.001). Proteomic analysis of left ventricular myocardial tissue provided insights into the impact of increased ITGA1 levels on cardiac fibrosis-related pathways and the contribution made by these changes to the development and progression of HFpEF.

CONCLUSIONS/INTERPRETATION

ITGA1 serves as a biomarker for monitoring cardiac structural and functional damage, can be used to accurately diagnose the presence of HFpEF, and can be used to predict potential deterioration in cardiac structure and function as well as re-hospitalisation for individuals with type 2 diabetes. Its measurement holds promise for facilitating risk stratification and early intervention to mitigate the adverse cardiovascular effects associated with diabetes.

DATA AVAILABILITY

The proteomic data of left ventricular myocardial tissue from individuals with type 2 diabetes, encompassing both those with and without HFpEF, is available from the ProteomeXchange database at http://proteomecentral.proteomexchange.org .

Global research trends and emerging opportunities for integrin adhesion complexes in cardiac repair: a scientometric analysis

Objective

Cardiac regenerative medicine has gained significant attention in recent years, and integrins are known to play a critical role in mediating cardiac development and repair, especially after an injury from the myocardial infarction (MI). Given the extensive research history and interdisciplinary nature of this field, a quantitative retrospective analysis and visualization of related topics is necessary.

Materials and methods

We performed a scientometric analysis of published papers on cardiac integrin adhesion complexes (IACs), including analysis of annual publications, disciplinary evolution, keyword co-occurrence, and literature co-citation.

Results

A total of 2,664 publications were finally included in the past 20 years. The United States is the largest contributor to the study and is leading this area of research globally. The journal Circulation Research attracts the largest number of high-quality publications. The study of IACs in cardiac repair/regenerative therapies involves multiple disciplines, particularly in materials science and developmental biology. Keywords of research frontiers were represented by Tenasin-C (2019-2023) and inflammation (2020-2023).

Conclusion

Integrins are topics with ongoing enthusiasm in biological development and tissue regeneration. The rapidly emerging role of matricellular proteins and non-protein components of the extracellular matrix (ECM) in regulating matrix structure and function may be a further breakthrough point in the future; the emerging role of IACs and their downstream molecular signaling in cardiac repair are also of great interest, such as induction of cardiac proliferation, differentiation, maturation, and metabolism, fibroblast activation, and inflammatory modulation.

Roles of Integrin in Cardiovascular Diseases: From Basic Research to Clinical Implications

Cardiovascular diseases (CVDs) pose a significant global health threat due to their complex pathogenesis and high incidence, imposing a substantial burden on global healthcare systems. Integrins, a group of heterodimers consisting of α and β subunits that are located on the cell membrane, have emerged as key players in mediating the occurrence and progression of CVDs by regulating the physiological activities of endothelial cells, vascular smooth muscle cells, platelets, fibroblasts, cardiomyocytes, and various immune cells. The crucial role of integrins in the progression of CVDs has valuable implications for targeted therapies. In this context, the development and application of various integrin antibodies and antagonists have been explored for antiplatelet therapy and anti-inflammatory-mediated tissue damage. Additionally, the rise of nanomedicine has enhanced the specificity and bioavailability of precision therapy targeting integrins. Nevertheless, the complexity of the pathogenesis of CVDs presents tremendous challenges for monoclonal targeted treatment. This paper reviews the mechanisms of integrins in the development of atherosclerosis, cardiac fibrosis, hypertension, and arrhythmias, which may pave the way for future innovations in the diagnosis and treatment of CVDs.

Integrin αV mediated activation of myofibroblast via mechanoparacrine of transforming growth factor β1 in promoting fibrous scar formation after myocardial infarction

BACKGROUND

Myocardial infarction (MI) dramatically changes the mechanical stress, which is intensified by the fibrotic remodeling. Integrins, especially the αV subunit, mediate mechanical signal and mechanoparacrine of transforming growth factor β1 (TGF-β1) in various organ fibrosis by activating CFs into myofibroblasts (MFBs). We investigated a possible role of integrin αV mediated mechanoparacrine of TGF-β1 in MFBs activation for fibrous reparation in mice with MI.

METHODS

Heart samples from MI, sham, or MI plus cilengitide (14 mg/kg, specific integrin αV inhibitor) treated mice, underwent functional and morphological assessments by echocardiography, and histochemistry on 7, 14 and 28 days post-surgery. The mechanical and ultrastructural changes of the fibrous scar were further evaluated by atomic mechanics microscope (AFM), immunofluorescence, second harmonic generation (SHG) imaging, polarized light and scanning electron microscope, respectively. Hydroxyproline assay was used for total collagen content, and western blot for protein expression profile examination. Fibroblast bioactivities, including cell shape, number, Smad2/3 signal and expression of extracellular matrix (ECM) related proteins, were further evaluated by microscopic observation and immunofluorescence in polyacrylamide (PA) hydrogel with adjustable stiffness, which was re-explored in fibroblast cultured on stiff matrix after silencing of integrin αV. The content of total and free TGF-β1 was tested by enzyme-linked immunosorbent assay (ELISA) in both infarcted tissue and cell samples.

RESULT

Increased stiffness with heterogeneity synchronized with integrin αV and alpha smooth muscle actin (α-SMA) positive MFBs accumulation in those less mature fibrous areas. Cilengitide abruptly reduced collagen content and disrupted collagen alignment, which also decreased TGF-β1 bioavailability, Smad2/3 phosphorylation, and α-SMA expression in the fibrous area. Accordingly, fibroblast on stiff but not soft matrix exhibited obvious MFB phenotype, as evidenced by enlarged cell, hyperproliferation, well-developed α-SMA fibers, and elevated ECM related proteins, while silencing of integrin αV almost abolished this switch via attenuating paracrine of TGF-β1 and nuclear translocation of Smad2/3.

CONCLUSION

This study illustrated that increased tissue stiffness activates CFs into MFBs by integrin αV mediated mechanoparacrine of TGF-β1, especially in immature scar area, which ultimately promotes fibrous scar maturation.

Kindlin-2 regulates colonic cancer stem-like cells survival and self-renewal via Wnt/β-catenin mediated pathway

BACKGROUND

Cancer Stem Cells (CSCs) have emerged as a critical mediator in recurrence and resistance in cancers. Kindlin-isoform (1 and 2) binds with cytoplasmic β-tail of integrin and are essential co-activators of integrin function. Given their important function in regulating cancer hallmarks such as cell proliferation, invasion, migration, and metastasis, we hypothesize that it might play a critical role in CSC growth, survival, and self-renewal of colon cancer.

MATERIALS AND METHODS

Using knockdown approaches, we inhibited Kindlin-2 expression in HCT116 and HT29 colon cancer cells. Extreme limiting dilution and self-renewal assay were performed to measure the role of Kindlin in colonic CSC. Standard methods such as qRT-PCR and western blotting were carried out to understand the signaling cascade by which Kindlin regulates CSC marker expression and downstream targets.

RESULTS

Our data show isoform-specific upregulation of Kindlin-2 in colonic CSCs. The silencing of Kindlin-2 reduces colonosphere formation, decreases CSC size, and self-renewal marker genes such as CD-133, CXCR-4, LGR-5, and C-MYC. Kindlin-2 silencing reduces colonosphere proliferation, invasion, and migration of colonic CSCs. Mechanistically, Kindlin-2 silencing reduces the expression, and nuclear localization of β-catenin, and decreases β-catenin target genes such as C-MYC, cyclin D1, DKK-1, and Snail-1.

CONCLUSION

Our study delineates the isoform-specific activity of Kindlin-2 in regulating Colonic CSC. Isoform-specific targeting of Kindlin-2 may be a novel strategy to tackle this devastating disease.

Inhibition of integrin alpha v/beta 5 mitigates the protective effect induced by irisin in hemorrhage

INTRODUCTION

Irisin plays an important role in regulating tissue stress, cardiac function, and inflammation. Integrin αvβ5 was recently identified as a receptor for irisin to elicit its physiologic function. It remains unknown whether integrin αvβ5 is required for irisin's function in modulating the physiologic response to hemorrhage. The objective of this study is to examine if integrin αvβ5 contributes to the effects of irisin during the hemorrhagic response.

METHODS

Hemorrhage was induced in mice by achieving a mean arterial blood pressure of 35-45 mmHg for one hour, followed by two hours of resuscitation. Irisin (0.5  μg/kg) was administrated to assess its pharmacologic effects in hemorrhage. Cilengitide, a cyclic Arg-Gly-Asp peptide (cRGDyK) which is an inhibitor of integrin αvβ5, or control RGDS (1 mg/kg) was administered with irisin. In another cohort of mice, the irisin-induced protective effect was examined after knocking down integrin β5 with nanoparticle delivery of integrin β5 sgRNA using CRSIPR/Cas-9 gene editing. Cardiac function and hemodynamics were measured using echocardiography and femoral artery catheterization, respectively. Systemic cytokine releases were measured using Enzyme-linked immunosorbent assay (ELISA). Histological analyses were used to determine tissue damage in myocardium, skeletal muscles, and lung tissues. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was carried out to assess apoptosis in tissues.

RESULTS

Hemorrhage induced reduction of integrin αvβ5 in skeletal muscles and repressed recovery of cardiac performance and hemodynamics. Irisin treatment led to significantly improved cardiac function, which was abrogated by treatment with Cilengitide or knockdown of integrin β5. Furthermore, irisin resulted in a marked suppression of tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1), muscle edema, and inflammatory cells infiltration in myocardium and skeletal muscles, which was attenuated by Cilengitide or knockdown of integrin β5. Irisin-induced reduction of apoptosis in the myocardium, skeletal muscles, and lung, which were attenuated by either the inhibition of integrin αvβ5, or knockdown of integrin β5.

CONCLUSION

Integrin αvβ5 plays an important role for irisin in modulating the protective effect during hemorrhage.

Transcriptomic profiling of mare endometrium at different stages of endometrosis

In the current study, transcriptome profiles of mare endometrium, classified into categories I, IIA, and IIB according to Kenney and Doig, were compared using RNA sequencing, analyzed, and functionally annotated using in silico analysis. In the mild stage (IIA) of endometrosis compared to category I endometrium, differentially expressed genes (DEGs) were annotated to inflammation, abnormal metabolism, wound healing, and quantity of connective tissue. In the moderate stage (IIB) of endometrosis compared to category I endometrium, DEGs were annotated to inflammation, fibrosis, cellular homeostasis, mitochondrial dysfunction, and pregnancy disorders. Ingenuity pathway analysis (IPA) identified cytokines such as transforming growth factor (TGF)-β1, interleukin (IL)-4, IL-13, and IL-17 as upstream regulators of DEGs associated with cellular homeostasis, metabolism, and fibrosis signaling pathways. In vitro studies showed the effect of these cytokines on DEGs such as ADAMTS1, -4, -5, -9, and HK2 in endometrial fibroblasts at different stages of endometrosis. The effect of cytokines on ADAMTS members' gene transcription in fibroblasts differs according to the severity of endometrosis. The identified transcriptomic changes associated with endometrosis suggest that inflammation and metabolic changes are features of mild and moderate stages of endometrosis. The changes of ADAMTS-1, -4, -5, -9, in fibrotic endometrium as well as in endometrial fibroblast in response to TGF-β1, IL-4, IL-13, and IL-17 suggest the important role of these factors in the development of endometrosis.

Dissecting the Molecular Mechanisms Driving Electropathology in Atrial Fibrillation: Deployment of RNA Sequencing and Transcriptomic Analyses

Despite many efforts to treat atrial fibrillation (AF), the most common progressive and age-related cardiac tachyarrhythmia in the Western world, the efficacy is still suboptimal. A plausible reason for this is that current treatments are not directed at underlying molecular root causes that drive electrical conduction disorders and AF (i.e., electropathology). Insights into AF-induced transcriptomic alterations may aid in a deeper understanding of electropathology. Specifically, RNA sequencing (RNA-seq) facilitates transcriptomic analyses and discovery of differences in gene expression profiles between patient groups. In the last decade, various RNA-seq studies have been conducted in atrial tissue samples of patients with AF versus controls in sinus rhythm. Identified differentially expressed molecular pathways so far include pathways related to mechanotransduction, ECM remodeling, ion channel signaling, and structural tissue organization through developmental and inflammatory signaling pathways. In this review, we provide an overview of the available human AF RNA-seq studies and highlight the molecular pathways identified. Additionally, a comparison is made between human RNA-seq findings with findings from experimental AF model systems and we discuss contrasting findings. Finally, we elaborate on new exciting RNA-seq approaches, including single-nucleotide variants, spatial transcriptomics and profiling of different populations of total RNA, small RNA and long non-coding RNA.

β1 integrins regulate cellular behaviors and cardiomyocyte organization during ventricular wall formation

Aims

The mechanisms regulating the cellular behavior and cardiomyocyte organization during ventricular wall morphogenesis are poorly understood. Cardiomyocytes are surrounded by extracellular matrix (ECM) and interact with ECM via integrins. This study aims to determine whether and how β1 integrins regulate cardiomyocyte behavior and organization during ventricular wall morphogenesis in the mouse.

Methods and Results

We applied mRNA deep sequencing and immunostaining to determine the expression repertoires of α/β integrins and their ligands in the embryonic heart. Integrin β1 subunit (β1) and some of its ECM ligands are asymmetrically distributed and enriched in the luminal side of cardiomyocytes, while fibronectin surrounds cardiomyocytes, creating a network for them. Itgb1 , which encodes the β1 integrin subunit, was deleted via Nkx2.5 Cre/+ to generate myocardial-specific Itgb1 knockout (B1KO) mice. B1KO hearts display an absence of trabecular zone but a thicker compact zone. The abundances of hyaluronic acid and versican are not significantly different. Instead, fibronectin, a ligand of β1, was absent in B1KO. We examined cellular behaviors and organization via various tools. B1KO cardiomyocytes display a random cellular orientation and fail to undergo perpendicular cell division, be organized properly, and establish the proper tissue architecture to form trabeculae. The reduction of Notch1 activation was not the cause of the abnormal cellular organization in B1KO hearts. Mosaic clonal lineage tracing shows that Itgb1 regulates cardiomyocyte transmural migration and proliferation autonomously.

Conclusions

β1 is asymmetrically localized in the cardiomyocytes, and its ECM ligands are enriched in the luminal side of the myocardium and surrounding cardiomyocytes. β1 integrins are required for cardiomyocytes to attach to the ECM network. This engagement provides structural support for cardiomyocytes to maintain shape, undergo perpendicular division, and establish cellular organization. Deletion of Itgb1 , leading to ablation of β1 integrins, causes the dissociation of cardiomyocytes from the ECM network and failure to establish tissue architecture to form trabeculae.

Cellular mechanotransduction in health and diseases: from molecular mechanism to therapeutic targets

Cellular mechanotransduction, a critical regulator of numerous biological processes, is the conversion from mechanical signals to biochemical signals regarding cell activities and metabolism. Typical mechanical cues in organisms include hydrostatic pressure, fluid shear stress, tensile force, extracellular matrix stiffness or tissue elasticity, and extracellular fluid viscosity. Mechanotransduction has been expected to trigger multiple biological processes, such as embryonic development, tissue repair and regeneration. However, prolonged excessive mechanical stimulation can result in pathological processes, such as multi-organ fibrosis, tumorigenesis, and cancer immunotherapy resistance. Although the associations between mechanical cues and normal tissue homeostasis or diseases have been identified, the regulatory mechanisms among different mechanical cues are not yet comprehensively illustrated, and no effective therapies are currently available targeting mechanical cue-related signaling. This review systematically summarizes the characteristics and regulatory mechanisms of typical mechanical cues in normal conditions and diseases with the updated evidence. The key effectors responding to mechanical stimulations are listed, such as Piezo channels, integrins, Yes-associated protein (YAP) /transcriptional coactivator with PDZ-binding motif (TAZ), and transient receptor potential vanilloid 4 (TRPV4). We also reviewed the key signaling pathways, therapeutic targets and cutting-edge clinical applications of diseases related to mechanical cues.

α1A Adrenoreceptor blockade attenuates myocardial infarction by modulating the integrin-linked kinase/TGF-β/Smad signaling pathways

Background

Myocardial infarction (MI) is considered a public health problem. According to the World Health Organization, MI is a leading cause of death and comorbidities worldwide. Activation of the α1A adrenergic receptor is a contributing factor to the development of MI. Tamsulosin, an α1A adrenergic blocker, has gained wide popularity as a medication for the treatment of benign prostatic hyperplasia. Limited evidence from previous studies has revealed the potential cardioprotective effects of tamsulosin, as its inhibitory effect on the α1A adrenoceptor protects the heart by acting on the smooth muscle of blood vessels, which results in hypotension; however, its effect on the infarcted heart is still unclear. The mechanisms of the expected cardioprotective effects mediated by tamsulosin are not yet understood. Transforming growth factor-beta (TGF-β), a mediator of fibrosis, is considered an attractive therapeutic target for remodeling after MI. The role of α1A adrenoceptor inhibition or its relationships with integrin-linked kinase (ILK) and TGF-β/small mothers against decapentaplegic (Smad) signaling pathways in attenuating MI are unclear. The present study was designed to investigate whether tamsulosin attenuates MI by modulating an ILK-related TGF-β/Smad pathway.

Methods

Twenty-four adult male Wistar rats were randomly divided into 4 groups: control, ISO, TAM, and ISO + TAM. ISO (150 mg/kg, intraperitoneally) was injected on Days 20 and 21 to induce MI. Tamsulosin (0.8 mg/kg, orally) was administered for 21 days, prior to ISO injection for 2 consecutive days. Heart-to-body weight ratios and cardiac and fibrotic biomarker levels were subsequently determined. ILK, TGF-β1, p-Smad2/3, and collagen III protein expression levels were determined using biomolecular methods.

Results

Tamsulosin significantly attenuated the relative heart-to-body weight index (p < 0.5) and creatine kinase-MB level (p < 0.01) compared with those in the ISO control group. While ISO resulted in superoxide anion production and enhanced oxidative damage, tamsulosin significantly prevented this damage through antioxidant defense mechanisms, increasing glutathione and superoxide dismutase levels (p < 0.05) and decreasing lipid peroxide oxidation levels (p < 0.01). The present data revealed that tamsulosin reduced TGF-β/p-Smad2/3 expression and enhanced ILK expression.

Conclusion

Tamsulosin may exert a cardioprotective effect by modulating the ILK-related TGF-β/Smad signaling pathway. Thus, tamsulosin may be a useful therapeutic approach for preventing MI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-023-03188-w.

Molecular mechanisms and targets of right ventricular fibrosis in pulmonary hypertension

Right ventricular fibrosis is a stress response, predominantly mediated by cardiac fibroblasts. This cell population is sensitive to increased levels of pro-inflammatory cytokines, pro-fibrotic growth factors and mechanical stimulation. Activation of fibroblasts results in the induction of various molecular signaling pathways, most notably the mitogen-activated protein kinase cassettes, leading to increased synthesis and remodeling of the extracellular matrix. While fibrosis confers structural protection in response to damage induced by ischemia or (pressure and volume) overload, it simultaneously contributes to increased myocardial stiffness and right ventricular dysfunction. Here, we review state-of-the-art knowledge of the development of right ventricular fibrosis in response to pressure overload and provide an overview of all published preclinical and clinical studies in which right ventricular fibrosis was targeted to improve cardiac function.

Activated fibroblasts in cardiac and cancer fibrosis: An overview of analogies and new potential therapeutic options

Heart disease and cancer are two major causes of morbidity and mortality in the industrialized countries, and their increasingly recognized connections are shifting the focus from single disease studies to an interdisciplinary approach. Fibroblast-mediated intercellular crosstalk is critically involved in the evolution of both pathologies. In healthy myocardium and in non-cancerous conditions, resident fibroblasts are the main cell source for synthesis of the extracellular matrix (ECM) and important sentinels of tissue integrity. In the setting of myocardial disease or cancer, quiescent fibroblasts activate, respectively, into myofibroblasts (myoFbs) and cancer-associated fibroblasts (CAFs), characterized by increased production of contractile proteins, and by a highly proliferative and secretory phenotype. Although the initial activation of myoFbs/CAFs is an adaptive process to repair the damaged tissue, massive deposition of ECM proteins leads to maladaptive cardiac or cancer fibrosis, a recognized marker of adverse outcome. A better understanding of the key mechanisms orchestrating fibroblast hyperactivity may help developing innovative therapeutic options to restrain myocardial or tumor stiffness and improve patient prognosis. Albeit still unappreciated, the dynamic transition of myocardial and tumor fibroblasts into myoFbs and CAFs shares several common triggers and signaling pathways relevant to TGF-β dependent cascade, metabolic reprogramming, mechanotransduction, secretory properties, and epigenetic regulation, which might lay the foundation for future antifibrotic intervention. Therefore, the aim of this review is to highlight emerging analogies in the molecular signature underlying myoFbs and CAFs activation with the purpose of identifying novel prognostic/diagnostic biomarkers, and to elucidate the potential of drug repositioning strategies to mitigate cardiac/cancer fibrosis.

The link between immunity and hypertension in the kidney and heart

Hypertension is the primary cause of cardiovascular disease, which is a leading killer worldwide. Despite the prevalence of this non-communicable disease, still between 90% and 95% of cases are of unknown or multivariate cause ("essential hypertension"). Current therapeutic options focus primarily on lowering blood pressure through decreasing peripheral resistance or reducing fluid volume, but fewer than half of hypertensive patients can reach blood pressure control. Hence, identifying unknown mechanisms causing essential hypertension and designing new treatment accordingly are critically needed for improving public health. In recent years, the immune system has been increasingly implicated in contributing to a plethora of cardiovascular diseases. Many studies have demonstrated the critical role of the immune system in the pathogenesis of hypertension, particularly through pro-inflammatory mechanisms within the kidney and heart, which, eventually, drive a myriad of renal and cardiovascular diseases. However, the precise mechanisms and potential therapeutic targets remain largely unknown. Therefore, identifying which immune players are contributing to local inflammation and characterizing pro-inflammatory molecules and mechanisms involved will provide promising new therapeutic targets that could lower blood pressure and prevent progression from hypertension into renal or cardiac dysfunction.

Nicotinamide riboside kinase-2 regulates metabolic adaptation in the ischemic heart

Ischemia-induced metabolic remodeling plays a critical role in the pathogenesis of adverse cardiac remodeling and heart failure however, the underlying molecular mechanism is largely unknown. Here, we assess the potential roles of nicotinamide riboside kinase-2 (NRK-2), a muscle-specific protein, in ischemia-induced metabolic switch and heart failure through employing transcriptomic and metabolomic approaches in ischemic NRK-2 knockout mice. The investigations revealed NRK-2 as a novel regulator of several metabolic processes in the ischemic heart. Cardiac metabolism and mitochondrial function and fibrosis were identified as top dysregulated cellular processes in the KO hearts post-MI. Several genes linked to mitochondrial function, metabolism, and cardiomyocyte structural proteins were severely downregulated in the ischemic NRK-2 KO hearts. Analysis revealed significantly upregulated ECM-related pathways which was accompanied by the upregulation of several key cell signaling pathways including SMAD, MAPK, cGMP, integrin, and Akt in the KO heart post-MI. Metabolomic studies identified profound upregulation of metabolites mevalonic acid, 3,4-dihydroxyphenylglycol, 2-penylbutyric acid, and uridine. However, other metabolites stearic acid, 8,11,14-eicosatrienoic acid, and 2-pyrrolidinone were significantly downregulated in the ischemic KO hearts. Taken together, these findings suggest that NRK-2 promotes metabolic adaptation in the ischemic heart. The aberrant metabolism in the ischemic NRK-2 KO heart is largely driven by dysregulated cGMP and Akt and mitochondrial pathways. KEY MESSAGES: Post-myocardial infarction metabolic switch critically regulates the pathogenesis of adverse cardiac remodeling and heart failure. Here, we report NRK-2 as a novel regulator of several cellular processes including metabolism and mitochondrial function post-MI. NRK-2 deficiency leads to downregulation of genes important for mitochondrial pathway, metabolism, and cardiomyocyte structural proteins in the ischemic heart. It was accompanied by upregulation of several key cell signaling pathways including SMAD, MAPK, cGMP, integrin, and Akt and dysregulation of numerous metabolites essential for cardiac bioenergetics. Taken together, these findings suggest that NRK-2 is critical for metabolic adaptation of the ischemic heart.

Observation of the protein expression level via naked eye: Pt clusters catalyze non-color molecules into brown-colored molecules in cells

α _v β ₃ is overexpressed in various tumor cells and plays a key role in tumor genesis, invasion, and metastasis. Therefore, it is of great significance to precisely detect the α _v β ₃ level in cells via a simple method. For this purpose, we have constructed a peptide-coated platinum (Pt) cluster. Due to its bright fluorescence, well-defined Pt atom numbers, and peroxidase-like catalytic activity, this cluster can be used to evaluate α _v β ₃ levels in cells by fluorescence imaging, inductively coupled plasma mass spectrometry (ICP-MS), and catalytic amplification of visual dyes, respectively. In this report, the expression level of α _v β ₃ in living cells is well-detected by the naked eye under an ordinary light microscope when the Pt cluster binds to αvβ3 in cells and catalyzes non-color 3,3'-diaminobenzidine (DAB) into brown-colored molecules in situ. Moreover, SiHa, HeLa, and 16HBE cell lines with different α _v β ₃ expression levels can be visually distinguished by the peroxidase-like Pt clusters. This research will provide a reliable method for the simple detection of α _v β ₃ levels in cells.

Calcitriol Suppressed Isoproterenol-induced Proliferation of Cardiac Fibroblasts via Integrin β3/FAK/Akt Pathway

OBJECTIVE

Cardiac fibroblasts (CFs) proliferation and extracellular matrix deposition are important features of cardiac fibrosis. Various studies have indicated that vitamin D displays an anti-fibrotic property in chronic heart diseases. This study explored the role of vitamin D in the growth of CFs via an integrin signaling pathway.

METHODS

MTT and 5-ethynyl-2'-deoxyuridine assays were performed to determine cell viability. Western blotting was performed to detect the expression of proliferating cell nuclear antigen (PCNA) and integrin signaling pathway. The fibronectin was observed by ELISA. Immunohistochemical staining was employed to evaluate the expression of integrin β3.

RESULTS

The PCNA expression in the CFs was enhanced after isoproterenol (ISO) stimulation accompanied by an elevated expression of integrin beta-3 (β3). The blockade of the integrin β3 with a specific integrin β3 antibody reduced the PCNA expression induced by the ISO. Decreasing the integrin β3 by siRNA reduced the ISO-triggered phosphorylation of FAK and Akt. Both the FAK inhibitor and Akt inhibitor suppressed the PCNA expression induced by the ISO in the CFs. Calcitriol (CAL), an active form of vitamin D, attenuated the ISO-induced CFs proliferation by downregulating the integrin β3 expression, and phosphorylation of FAK and Akt. Moreover, CAL reduced the increased levels of fibronectin and hydroxyproline in the CFs culture medium triggered by the ISO. The administration of calcitriol decreased the integrin β3 expression in the ISO-induced myocardial injury model.

CONCLUSION

These findings revealed a novel role for CAL in suppressing the CFs growth by the downregulation of the integrin β3/FAK/Akt pathway.

Mechanical stress regulates the mechanotransduction and metabolism of cardiac fibroblasts in fibrotic cardiac diseases

Fibrotic cardiac diseases are characterized by myocardial fibrosis that results in maladaptive cardiac remodeling. Cardiac fibroblasts (CFs) are the main cell type responsible for fibrosis. In response to stress or injury, intrinsic CFs develop into myofibroblasts and produce excess extracellular matrix (ECM) proteins. Myofibroblasts are mechanosensitive cells that can detect changes in tissue stiffness and respond accordingly. Previous studies have revealed that some mechanical stimuli control fibroblast behaviors, including ECM formation, cell migration, and other phenotypic traits. Further, metabolic alteration is reported to regulate fibrotic signaling cascades, such as the transforming growth factor-β pathway and ECM deposition. However, the relationship between metabolic changes and mechanical stress during fibroblast-to-myofibroblast transition remains unclear. This review aims to elaborate on the crosstalk between mechanical stress and metabolic changes during the pathological transition of cardiac fibroblasts.

Garlic (Allium sativum L.) in diabetes and its complications: Recent advances in mechanisms of action

Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycemia and impaired islet secretion that places a heavy burden on the global health care system due to its high incidence rate, long disease course and many complications. Fortunately, garlic (Allium sativum L.), a well-known medicinal plant and functional food without the toxicity and side effects of conventional drugs, has shown positive effects in the treatment of diabetes and its complications. With interdisciplinary development and in-depth exploration, we offer a clear and comprehensive summary of the research from the past ten years, focusing on the mechanisms and development processes of garlic in the treatment of diabetes and its complications, aiming to provide a new perspective for the treatment of diabetes and promote the efficient development of this field.

Exploring the cardiac ECM during fibrosis: A new era with next-gen proteomics

Extracellular matrix (ECM) plays a critical role in maintaining elasticity in cardiac tissues. Elasticity is required in the heart for properly pumping blood to the whole body. Dysregulated ECM remodeling causes fibrosis in the cardiac tissues. Cardiac fibrosis leads to stiffness in the heart tissues, resulting in heart failure. During cardiac fibrosis, ECM proteins get excessively deposited in the cardiac tissues. In the ECM, cardiac fibroblast proliferates into myofibroblast upon various kinds of stimulations. Fibroblast activation (myofibroblast) contributes majorly toward cardiac fibrosis. Other than cardiac fibroblasts, cardiomyocytes, epithelial/endothelial cells, and immune system cells can also contribute to cardiac fibrosis. Alteration in the expression of the ECM core and ECM-modifier proteins causes different types of cardiac fibrosis. These different components of ECM culminated into different pathways inducing transdifferentiation of cardiac fibroblast into myofibroblast. In this review, we summarize the role of different ECM components during cardiac fibrosis progression leading to heart failure. Furthermore, we highlight the importance of applying mass-spectrometry-based proteomics to understand the key changes occurring in the ECM during fibrotic progression. Next-gen proteomics studies will broaden the potential to identify key targets to combat cardiac fibrosis in order to achieve precise medicine-development in the future.

Integrins in cardiac fibrosis

Cells sense mechanical stress and changes in their matrix environment through the integrins, a family of heterodimeric surface receptors that bind to extracellular matrix ligands and trigger cytoskeletal remodeling, while transducing a wide range of intracellular signals. Integrins have been extensively implicated in regulation of inflammation, repair and fibrosis in many different tissues. This review manuscript discusses the role of integrin-mediated cascades in myocardial fibrosis. In vitro studies have demonstrated that β1 and αv integrins play an important role in fibrogenic conversion of cardiac fibroblast, acting through direct stimulation of FAK/Src cascades, or via accentuation of growth factor signaling. Fibrogenic actions of αv integrins may be mediated, at least in part, through pericellular activation of latent TGF-β stores. In vivo evidence supporting the role of integrin heterodimers in fibrotic cardiac remodeling is limited to associative evidence, and to experiments using pharmacologic inhibitors, or global loss-of-function approaches. Studies documenting in vivo actions of integrins on fibroblasts using cell-specific strategies are lacking. Integrin effects on leukocytes may also contribute to the pathogenesis of fibrotic myocardial responses by mediating recruitment and activation of fibrogenic macrophages. The profile and role of integrins in cardiac fibrosis may be dependent on the underlying pathologic condition. Considering their cell surface localization and the availability of small molecule inhibitors, integrins may be attractive therapeutic targets for patients with heart failure associated with prominent fibrotic remodeling.

Modulation of integrin receptor by polyphenols: Downstream Nrf2-Keap1/ARE and associated cross-talk mediators in cardiovascular diseases

As a group of heterodimeric and transmembrane glycoproteins, integrin receptors are widely expressed in various cell types overall the body. During cardiovascular dysfunction, integrin receptors apply inhibitory effects on the antioxidative pathways, including nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch like ECH Associated Protein 1 (Keap1)/antioxidant response element (ARE) and interconnected mediators. As such, dysregulation in integrin signaling pathways influences several aspects of cardiovascular diseases (CVDs) such as heart failure, arrhythmia, angina, hypertension, hyperlipidemia, platelet aggregation and coagulation. So, modulation of integrin pathway could trigger the downstream antioxidant pathways toward cardioprotection. Regarding the involvement of multiple aforementioned mediators in the pathogenesis of CVDs, as well as the side effects of conventional drugs, seeking for novel alternative drugs is of great importance. Accordingly, the plant kingdom could pave the road in the treatment of CVDs. Of natural entities, polyphenols are multi-target and accessible phytochemicals with promising potency and low levels of toxicity. The present study aims at providing the cardioprotective roles of integrin receptors and downstream antioxidant pathways in heart failure, arrhythmia, angina, hypertension, hyperlipidemia, platelet aggregation and coagulation. The potential role of polyphenols has been also revealed in targeting the aforementioned dysregulated signaling mediators in those CVDs.

A positive mechanobiological feedback loop controls bistable switching of cardiac fibroblast phenotype

Cardiac fibrosis is associated with activation of cardiac fibroblasts (CFs), a pathological, phenotypic transition that is widely believed to be irreversible in the late stages of disease development. Sensing of a stiffened mechanical environment through regulation of integrin-based adhesion plaques and activation of the Piezo1 mechanosensitive ion channel is known to factor into this transition. Here, using integrated in vitro and in silico models, we discovered a mutually reinforcing, mechanical positive feedback loop between integrin β1 and Piezo1 activation that forms a bistable switch. The bistable switch is initiated by perturbations in matrix elastic modulus that amplify to trigger downstream signaling involving Ca²⁺ and YAP that, recursively, leads fibroblasts to further stiffen their environment. By simultaneously interfering with the newly identified mechanical positive feedback loop and modulating matrix elastic modulus, we reversed markers of phenotypical transition of CF, suggesting new therapeutic targets for fibrotic disease.

Bioinformatics and System Biological Approaches for the Identification of Genetic Risk Factors in the Progression of Cardiovascular Disease

Background

Cardiovascular disease (CVD) is the combination of coronary heart disease, myocardial infarction, rheumatic heart disease, and peripheral vascular disease of the heart and blood vessels. It is one of the leading deadly diseases that causes one-third of the deaths yearly in the globe. Additionally, the risk factors associated with it make the situation more complex for cardiovascular patients, which lead them towards mortality, but the genetic association between CVD and its risk factors is not clearly explored in the global literature. We addressed this issue and explored the linkage between CVD and its risk factors.

Methods

We developed an analytical approach to reveal the risk factors and their linkages with CVD. We used GEO microarray datasets for the CVD and other risk factors in this study. We performed several analyses including gene expression analysis, diseasome analysis, protein-protein interaction (PPI) analysis, and pathway analysis for discovering the relationship between CVD and its risk factors. We also examined the validation of our study using gold benchmark databases OMIM, dbGAP, and DisGeNET.

Results

We observed that the number of 32, 17, 53, 70, and 89 differentially expressed genes (DEGs) is overlapped between CVD and its risk factors of hypertension (HTN), type 2 diabetes (T2D), hypercholesterolemia (HCL), obesity, and aging, respectively. We identified 10 major hub proteins (FPR2, TNF, CXCL8, CXCL1, IL1B, VEGFA, CYBB, PTGS2, ITGAX, and CCR5), 12 significant functional pathways, and 11 gene ontological pathways that are associated with CVD. We also found the connection of CVD with its risk factors in the gold benchmark databases. Our experimental outcomes indicate a strong association of CVD with its risk factors of HTN, T2D, HCL, obesity, and aging.

Conclusions

Our computational approach explored the genetic association of CVD with its risk factors by identifying the significant DEGs, hub proteins, and signaling and ontological pathways. The outcomes of this study may be further used in the lab-based analysis for developing the effective treatment strategies of CVD.

Effect of cardioplegic arrest and reperfusion on left and right ventricular proteome/phosphoproteome in patients undergoing surgery for coronary or aortic valve disease

Our earlier work has shown inter‑disease and intra‑disease differences in the cardiac proteome between right (RV) and left (LV) ventricles of patients with aortic valve stenosis (AVS) or coronary artery disease (CAD). Whether disease remodeling also affects acute changes occuring in the proteome during surgical intervention is unknown. This study investigated the effects of cardioplegic arrest on cardiac proteins/phosphoproteins in LV and RV of CAD (n=6) and AVS (n=6) patients undergoing cardiac surgery. LV and RV biopsies were collected during surgery before ischemic cold blood cardioplegic arrest (pre) and 20 min after reperfusion (post). Tissues were snap frozen, proteins extracted, and the extracts were used for proteomic and phosphoproteomic analysis using Tandem Mass Tag (TMT) analysis. The results were analysed using QuickGO and Ingenuity Pathway Analysis softwares. For each comparision, our proteomic analysis identified more than 3,000 proteins which could be detected in both the pre and Post samples. Cardioplegic arrest and reperfusion were associated with significant differential expression of 24 (LV) and 120 (RV) proteins in the CAD patients, which were linked to mitochondrial function, inflammation and cardiac contraction. By contrast, AVS patients showed differential expression of only 3 LV proteins and 2 RV proteins, despite a significantly longer duration of ischaemic cardioplegic arrest. The relative expression of 41 phosphoproteins was significantly altered in CAD patients, with 18 phosphoproteins showing altered expression in AVS patients. Inflammatory pathways were implicated in the changes in phosphoprotein expression in both groups. Inter‑disease comparison for the same ventricular chamber at both timepoints revealed differences relating to inflammation and adrenergic and calcium signalling. In conclusion, the present study found that ischemic arrest and reperfusion trigger different changes in the proteomes and phosphoproteomes of LV and RV of CAD and AVS patients undergoing surgery, with markedly more changes in CAD patients despite a significantly shorter ischaemic period.

Piezo2 is not an indispensable mechanosensor in murine cardiomyocytes

A short-term increase in ventricular filling leads to an immediate (Frank-Starling mechanism) and a slower (Anrep effect) rise in cardiac contractility, while long-term increased cardiac load (e.g., in arterial hypertension) decreases contractility. Whether these answers to mechanical tension are mediated by specific sensors in cardiomyocytes remains elusive. In this study, the piezo2 protein was evaluated as a potential mechanosensor. Piezo2 was found to be upregulated in various rat and mouse cardiac tissues upon mechanical or pharmacological stress. To investigate its function, C57BL/6J mice with homozygous cardiomyocyte-specific piezo2 knockout [Piezo2-KO] were created. To this end, α-MHC-Cre mice were crossed with homozygous "floxed" piezo2 mice. α-MHC-Cre mice crossed with wildtype mice served as controls [WT-Cre⁺]. In cardiomyocytes of Piezo2-KO mice, piezo2 mRNA was reduced by > 90% and piezo2 protein was not detectable. Piezo2-KO mice displayed no morphological abnormalities or altered cardiac function under nonstressed conditions. In a subsequent step, hearts of Piezo2-KO or WT-Cre⁺-mice were stressed by either three weeks of increased afterload (angiotensin II, 2.5 mg/kg/day) or one week of hypercontractility (isoprenaline, 30 mg/kg/day). As expected, angiotensin II treatment in WT-Cre⁺-mice resulted in higher heart and lung weight (per body weight, + 38%, + 42%), lower ejection fraction and cardiac output (- 30%, - 39%) and higher left ventricular anterior and posterior wall thickness (+ 34%, + 37%), while isoprenaline led to higher heart weight (per body weight, + 25%) and higher heart rate and cardiac output (+ 24%, + 54%). The Piezo2-KO mice reacted similarly with the exception that the angiotensin II-induced increases in wall thickness were blunted and the isoprenaline-induced increase in cardiac output was slightly less pronounced. As cardiac function was neither severely affected under basal nor under stressed conditions in Piezo2-KO mice, we conclude that piezo2 is not an indispensable mechanosensor in cardiomyocytes.

Integrin α11β1 and syndecan-4 dual receptor ablation attenuates cardiac hypertrophy in the pressure overloaded heart

Pathological myocardial hypertrophy in response to an increase in left ventricular (LV) afterload may ultimately lead to heart failure. Cell surface receptors bridge the interface between the cell and the ECM in cardiac myocytes and cardiac fibroblasts, and have been suggested to be important mediators of pathological myocardial hypertrophy. We identify for the first time that integrin α11 (α11) is preferentially upregulated amongst integrin beta 1 heterodimer-forming α subunits in response to increased afterload induced by aortic banding (AB) in wild type mice (WT). Mice were anesthetized in a chamber with 4% isoflurane and 95% oxygen before being intubated and ventilated with 2.5% isoflurane and 97% oxygen. For pre- and post-operative analgesia, animals were administered 0.02 mL buprenorphine (0.3 mg/mL) subcutaneously. Surprisingly, mice lacking α11 develop myocardial hypertrophy following AB comparable to WT. In the mice lacking α11, we further show a compensatory increase in the expression of another mechanoreceptor, syndecan-4, following AB compared to WT AB mice, indicating that syndecan-4 compensated for lack of α11. Intriguingly, mice lacking mechanoreceptors α11 and syndecan-4 show ablated myocardial hypertrophy following AB compared to WT mice. Expression of the main cardiac collagen isoforms col1a2 and col3a1 was significantly reduced in AB mice lacking mechanoreceptors α11 and syndecan-4 compared to WT AB.

Collagen type XIX regulates cardiac extracellular matrix structure and ventricular function

The cardiac extracellular matrix plays essential roles in homeostasis and injury responses. Although the role of fibrillar collagens have been thoroughly documented, the functions of non-fibrillar collagen members remain underexplored. These include a distinct group of non-fibrillar collagens, termed, fibril-associated collagens with interrupted triple helices (FACITs). Recent reports of collagen type XIX (encoded by Col19a1) expression in adult heart and evidence of its enhanced expression in cardiac ischemia suggest important functions for this FACIT in cardiac ECM structure and function. Here, we examined the cellular source of collagen XIX in the adult murine heart and evaluated its involvement in ECM structure and ventricular function. Immunodetection of collagen XIX in fractionated cardiovascular cell lineages revealed fibroblasts and smooth muscle cells as the primary sources of collagen XIX in the heart. Based on echocardiographic and histologic analyses, Col19a1 null (Col19a1N/N) mice exhibited reduced systolic function, thinning of left ventricular walls, and increased cardiomyocyte cross-sectional areas-without gross changes in myocardial collagen content or basement membrane morphology. Col19a1N/N cardiac fibroblasts had augmented expression of several enzymes involved in the synthesis and stability of fibrillar collagens, including PLOD1 and LOX. Furthermore, second harmonic generation-imaged ECM derived from Col19a1N/N cardiac fibroblasts, and transmission electron micrographs of decellularized hearts from Col19a1N/N null animals, showed marked reductions in fibrillar collagen structural organization. Col19a1N/N mice also displayed enhanced phosphorylation of focal adhesion kinase (FAK), signifying de-repression of the FAK pathway-a critical mediator of cardiomyocyte hypertrophy. Collectively, we show that collagen XIX, which had a heretofore unknown role in the mammalian heart, participates in the regulation of cardiac structure and function-potentially through modulation of ECM fibrillar collagen structural organization. Further, these data suggest that this FACIT may modify ECM superstructure via acting at the level of the fibroblast to regulate their expression of collagen synthetic and stabilization enzymes.

Truncation of the N-terminus of cardiac troponin I initiates adaptive remodeling of the myocardial proteosome via phosphorylation of mechano-sensitive signaling pathways

The cardiac isoform of troponin I has a unique N-terminal extension (~ 1-30 amino acids), which contributes to the modulation of cardiac contraction and relaxation. Hearts of various species including humans produce a truncated variant of cardiac troponin I (cTnI-ND) deleting the first ~ 30 amino acids as an adaption in pathophysiological conditions. In this study, we investigated the impact of cTnI-ND chronic expression in transgenic mouse hearts compared to wildtype (WT) controls (biological n = 8 in each group). We aimed to determine the global phosphorylation effects of cTnI-ND on the cardiac proteome, thereby determining the signaling pathways that have an impact on cardiac function. The samples were digested and isobarically labeled and equally mixed for relative quantification via nanoLC-MS/MS. The peptides were then enriched for phospho-peptides and bioinformatic analysis was done with Ingenuity Pathway Analysis (IPA). We found approximately 77% replacement of the endogenous intact cTnI with cTnI-ND in the transgenic mouse hearts with 1674 phospho-proteins and 2971 non-modified proteins. There were 73 significantly altered phospho-proteins; bioinformatic analysis identified the top canonical pathways as associated with integrin, protein kinase A, RhoA, and actin cytoskeleton signaling. Among the 73 phospho-proteins compared to controls cTnI-ND hearts demonstrated a significant decrease in paxillin and YAP1, which are known to play a role in cell mechano-sensing pathways. Our data indicate that cTnI-ND modifications in the sarcomere are sufficient to initiate changes in the phospho-signaling profile that may underly the chronic-adaptive response associated with cTnI cleavage in response to stressors by modifying mechano-sensitive signaling pathways.

Mechanosensitive Piezo1 channels mediate renal fibrosis

Kidney fibrosis is the final common pathway of progressive kidney diseases, the underlying mechanisms of which is not fully understood. The purpose of the current study is to investigate a role of Piezo1, a mechanosensitive nonselective cation channel, in kidney fibrosis. In human fibrotic kidneys, Piezo1 protein expression was markedly upregulated. The abundance of Piezo1 protein in kidneys of mice with UUO or with folic-acid treatment was significantly increased. Inhibition of Piezo1 with GsMTx4 markedly ameliorated UUO or folic acid-induced kidney fibrosis. Mechanical stretch, compression or stiffness induced Piezo1 activation and pro-fibrotic responses in human HK2 cells and primary cultured mouse proximal tubular cells (mPTCs), which were greatly prevented by inhibition or silence of Piezo1. TGFβ-1 induced increased Piezo1 expression and pro-fibrotic phenotypic alterations in HK2 cells and mPTCs, which was again markedly prevented by inhibition of Piezo1. Activation of Piezo1 by Yoda1, a Piezo1 agonist, caused calcium influx and profibrotic responses in HK2 cells and induced calpain2 activation, followed by talin1 cleavage and upregulation of integrinβ1. Also, Yoda1 promoted the link between ECM and integrinβ1. In conclusion, Piezo1 is involved in the progression of kidney fibrosis and pro-fibrotic alterations in renal proximal tubular cells, likely through activating calcium-calpain2-integrinβ1 pathway.

Positron Emission Tomography (PET) with 18F-FGA for Diagnosis of Myocardial Infarction in a Coronary Artery Ligation Model

Location and extent of necrosis are valuable information in the management of myocardial infarction (MI). Methods. We investigated 2-deoxy-2-18F-fluoro glucaric acid (FGA), a novel infarct-avid agent, for positron emission tomography (PET) of MI. We synthesized FGA from commercially available 18F-fluoro-2-deoxy-2-D-glucose (FDG). MI was induced in mice by permanently occluding the left anterior descending coronary artery. Biodistribution of FGA was assessed 1 h after FGA injection (11 MBq). PET/CT was conducted 1 h, 6 h, 1 d, 3 d, and 4 d after MI. Subcellular compartment of FGA accumulation in necrosis was studied by tracing the uptake of biotin-labeled glucaric acid with streptavidin-HRP in H2O2-treated H9c2 cardiomyoblasts. Streptavidin-reactive protein bands were identified by LC-MS/MS. Results. We obtained a quantitative yield of FGA from FDG within 7 min ( $\text{radiochemical}\text{purity}>99\%$ ). Cardiac uptake of FGA was significantly higher in MI mice than that in control mice. Imaging after 1 h of FGA injection delineated MI for 3 days after MI induction, with negligible background signal from surrounding tissues. Myocardial injury was verified by tetrazolium staining and plasma troponin (47.63 pg/mL control versus 311.77 pg/mL MI). In necrotic H9c2 myoblasts, biotinylated glucaric acid accumulated in nuclear fraction. LC-MS/MS primarily identified fibronectin in necrotic cells as a putative high fidelity target of glucaric acid. Conclusion. FGA/PET detects infarct early after onset of MI and FGA accumulation in infarct persists for 3 days. Its retention in necrotic cells appears to be a result of interaction with fibronectin that is known to accumulate in injured cardiac tissue.

Zyxin protects from hypertension-induced cardiac dysfunction

Arterial hypertension causes left ventricular hypertrophy leading to dilated cardiomyopathy. Following compensatory cardiomyocyte hypertrophy, cardiac dysfunction develops due to loss of cardiomyocytes preceded or paralleled by cardiac fibrosis. Zyxin acts as a mechanotransducer in vascular cells that may promote cardiomyocyte survival. Here, we analyzed cardiac function during experimental hypertension in zyxin knockout (KO) mice. In zyxin KO mice, made hypertensive by way of deoxycorticosterone acetate (DOCA)-salt treatment telemetry recording showed an attenuated rise in systolic blood pressure. Echocardiography indicated a systolic dysfunction, and isolated working heart measurements showed a decrease in systolic elastance. Hearts from hypertensive zyxin KO mice revealed increased apoptosis, fibrosis and an upregulation of active focal adhesion kinase as well as of integrins α5 and β1. Both interstitial and perivascular fibrosis were even more pronounced in zyxin KO mice exposed to angiotensin II instead of DOCA-salt. Stretched microvascular endothelial cells may release collagen 1α2 and TGF-β, which is characteristic for the transition to an intermediate mesenchymal phenotype, and thus spur the transformation of cardiac fibroblasts to myofibroblasts resulting in excessive scar tissue formation in the heart of hypertensive zyxin KO mice. While zyxin KO mice per se do not reveal a cardiac phenotype, this is unmasked upon induction of hypertension and owing to enhanced cardiomyocyte apoptosis and excessive fibrosis causes cardiac dysfunction. Zyxin may thus be important for the maintenance of cardiac function in spite of hypertension.

Nicotinamide riboside kinase-2 inhibits JNK pathway and limits dilated cardiomyopathy in mice with chronic pressure overload

Nicotinamide riboside kinase-2 (NRK-2) has recently emerged as a critical regulator of cardiac remodeling however, underlying molecular mechanisms is largely unknown. To explore the same, NRK2 knockout (KO) and littermate control mice were subjected to trans-aortic constriction (TAC) or sham surgeries and cardiac function was assessed by serial M-mode echocardiography. A mild cardiac contractile dysfunction was observed in the KOs at the early adaptive phase of remodeling followed by a significant deterioration during the maladaptive cardiac remodeling phase. Consistently, NRK2 KO hearts displayed increased cardiac hypertrophy and heart failure reflected by morphometric parameters as well as increased fetal genes ANP and BNP expressions. Histological assessment revealed an extensive left ventricular (LV) chamber dilatation accompanied by elevated cardiomyopathy and fibrosis in the KO hearts post-TAC. In a gain-of-function model, NRK-2 overexpressing in AC16 cardiomyocytes displayed significantly attenuated fetal genes ANP and BNP expression. Consistently, NRK-2 overexpression attenuated angiotensin II- induced cardiomyocyte death. Mechanistically, we identified NRK-2 as a regulator of JNK MAP kinase and mitochondrial function where NRK-2 overexpression in human cardiomyocytes markedly suppressed the angiotensin II- induced JNK activation and mitochondrial depolarization. Thus, our results demonstrate that NRK-2 plays protective roles in pressure overload- induced dilatative cardiac remodeling and, genetic ablation exacerbates dilated cardiomyopathy, interstitial collagen deposition, and cardiac dysfunction post-TAC due, in part, to increased JNK activation and mitochondrial dysfunction.

The Stiffness of Cardiac Fibroblast Substrates Exerts a Regulatory Influence on Collagen Metabolism via α2β1 Integrin, FAK and Src Kinases

Information about mechanical strain in the extracellular space is conducted along collagen fibers connected with integrins and then transmitted within cells. An aim of the study is to verify the hypothesis that the stiffness of cardiac human fibroblast substrates exerts a regulatory effect on collagen metabolism via integrin α2β1 and downstream signaling. The experiments were performed on human cardiac fibroblasts cultured on stiff or soft polyacrylamide gels. Extracellular and intracellular collagen content, metalloproteinase-1 (MMP-1), metalloproteinase-9 (MMP-9) and expression of the α1 chain of the procollagen type I gene (Col1A1) were elevated in cultures settled on soft substrate. The substrate stiffness did not modify tissue inhibitors of matrix metalloproteinase capacity (TIMPs 1–4). Integrin α2β1 inhibition (TC-I 15) or α2 subunit silencing resulted in augmentation of collagen content within the culture. Expression of Col1A1 and Col3A1 genes was increased in TC-I 15-treated fibroblasts. Total and phosphorylated levels of both FAK and Src kinases were elevated in fibroblasts cultured on stiff substrate. Inhibition of FAK (FAK kinase inhibitor 14) or Src kinase (AZM 47527) increased collagen content within the culture. The substrate stiffness exerted a regulatory influence on collagen metabolism via integrin α2β1 and its downstream signaling (FAK and Src kinases) in cardiac fibroblasts.

Effects of emodin, a plant-derived anthraquinone, on TGF-β1-induced cardiac fibroblast activation and function

Cardiac fibrosis accompanies a number of pathological conditions and results in altered myocardial structure, biomechanical properties and function. The signaling networks leading to fibrosis are complex, contributing to the general lack of progress in identifying effective therapeutic approaches to prevent or reverse this condition. Several studies have shown protective effects of emodin, a plant-derived anthraquinone, in animal models of fibrosis. A number of questions remain regarding the mechanisms whereby emodin impacts fibrosis. Transforming growth factor beta 1 (TGF-β1) is a potent stimulus of fibrosis and fibroblast activation. In the present study, experiments were performed to evaluate the effects of emodin on activation and function of cardiac fibroblasts following treatment with TGF-β1. We demonstrate that emodin attenuates TGF-β1-induced fibroblast activation and collagen accumulation in vitro. Emodin also inhibits activation of several canonical (SMAD2/3) and noncanonical (Erk1/2) TGF-β signaling pathways, while activating the p38 pathway. These results suggest that emodin may provide an effective therapeutic agent for fibrosis that functions via specific TGF-β signaling pathways.

Dual integrin αvβ3 and αvβ5 blockade attenuates cardiac dysfunction by reducing fibrosis in a rat model of doxorubicin-induced cardiomyopathy

OBJECTIVE

The present study aimed to evaluate the protective role of cilengitide (CGT), an integrin αvβ3 and αvβ5 inhibitor, on doxorubicin (DOX)-induced myocardial fibrosis and cardiac dysfunction in a rat model. Methods. Forty male rats were randomly divided into four groups: DOX (n = 12), intraperitoneal (i.p.) injection of DOX 0.8 ∼ 1.0 mg/kg three times a week for up to 6 weeks, then saline i.p. three times a week for another 3 weeks; CGT (n = 8), CGT 10 mg/kg, i.p. three times a week for 9 weeks; DOX + CGT (n = 12), DOX and CGT co-administration as above for 6 weeks, then CGT alone for another 3 weeks; Control (n = 8), saline i.p. three times a week for 9 weeks. Echocardiography, serum procollagen I C-terminal propeptide (PICP) procollagen III N-terminal propeptide (PIIINP) and C telopeptide type I (CTX-I) were evaluated at baseline and 3, 6 and 9 weeks after initial DOX administration for all surviving rats. The heart tissues were then harvested for myocardial hydroxyproline (HYP) evaluation, qRT-PCR, and western blotting. Results. CGT attenuated DOX-induced eccentric remodeling by improving relative wall thickness at the 9th week. CGT also improved systolic function at the 9th week and diastolic function at the 6th and 9th week. CGT reduced myocardial HYP and serum PICP, PIIINP, CTX-I, and the PICP/PIIINP ratio. RT-PCR and western blot showed that CGT blocked the TGF-β1/SMAD3 pathway and mitigating extracellular matrix turnover. Conclusions. CGT exerted a cardioprotective effect against doxorubicin-induced fibrosis and improved cardiac function.

Cardioprotection of an IK1 channel agonist on L-thyroxine induced rat ventricular remodeling

Downregulation of inward rectifier potassium (I_K1) channel is a hallmark in cardiac hypertrophy and failure. The cardioprotection of zacopride (a selective I_K1 agonist) and underlying mechanisms were investigated in L-thyroxine (T4) or Triiodothyronine (T3)-induced cardiac remodeling. In the in vivo study, adult male Sprague-Dawley (SD) rats were randomly divided into control, L-thyroxine, L-thy+zacopride, and L-thy+zacopride+chloroquine (an I_K1 antagonist) groups. Echocardiography, histopathology, TUNEL assay, western blotting and confocal imaging for intracellular Ca²⁺ fluorescence were performed. In the in vitro study, zacopride and nifedipine (a LTCC blocker) were used to compare their effects on Kir2.1, SAP97, autophagy, and [Ca²⁺]_i in H9C2 (2-1) cardiomyocytes. Zacopride treatment attenuated L-thyroxine- or T3 induced cardiac remodeling and dysfunction which manifested as cardiac hypertrophy and collagen deposition, dilated ventricle, decreased ejection fraction (EF), increased cardiomyocytes apoptosis, hyper-activation of CaMKII and PI3K/Akt/mTOR signaling, decreased cardiac autophagy, and increased expression of integrin β3. The cardioprotection of zacopride is strongly associated with the upregulation of I_K1, SAP97, and [Ca²⁺]_i homeostasis in cardiomyocytes. I_K1 antagonist chloroquine or BaCl₂ reversed these effects. Nifedipine could attenuate intracellular Ca²⁺ overload with no significant effects on I_K1, SAP97, and autophagy. This study showed that zacopride could improve cardiac remodeling via facilitating Kir2.1 forward trafficking, and negatively regulating calcium-activated and PI3K/Akt/mTOR signalings, in an I_K1-dependent manner.

The role of basement membranes in cardiac biology and disease

Basement membranes are highly specialised extracellular matrix structures that within the heart underlie endothelial cells and surround cardiomyocytes and vascular smooth muscle cells. They generate a dynamic and structurally supportive environment throughout cardiac development and maturation by providing physical anchorage to the underlying interstitium, structural support to the tissue, and by influencing cell behaviour and signalling. While this provides a strong link between basement membrane dysfunction and cardiac disease, the role of the basement membrane in cardiac biology remains under-researched and our understanding regarding the mechanistic interplay between basement membrane defects and their morphological and functional consequences remain important knowledge-gaps. In this review we bring together emerging understanding of basement membrane defects within the heart including in common cardiovascular pathologies such as contractile dysfunction and highlight some key questions that are now ready to be addressed.

Key Roles of RGD-Recognizing Integrins During Cardiac Development, on Cardiac Cells, and After Myocardial Infarction

Cardiac cells interact with the extracellular matrix (ECM) proteins through integrin mechanoreceptors that control many cellular events such as cell survival, apoptosis, differentiation, migration, and proliferation. Integrins play a crucial role in cardiac development as well as in cardiac fibrosis and hypertrophy. Integrins recognize oligopeptides present on ECM proteins and are involved in three main types of interaction, namely with collagen, laminin, and the oligopeptide RGD (Arg-Gly-Asp) present on vitronectin and fibronectin proteins. To date, the specific role of integrins recognizing the RGD has not been addressed. In this review, we examine their role during cardiac development, their role on cardiac cells, and their upregulation during pathological processes such as heart fibrosis and hypertrophy. We also examine their role in regenerative and angiogenic processes after myocardial infarction (MI) in the peri-infarct area. Specific targeting of these integrins may be a way of controlling some of these pathological events and thereby improving medical outcomes.

Expression and Pathogenic Analysis of Integrin Family Genes in Systemic Sclerosis

Objectives: Emerging evidence shows that integrin members are involved in inflammation and fibrosis in systemic sclerosis (SSc). This study aimed at evaluating the expression of integrin family genes in the skin tissue from SSc patients and exploring the potential pathogenic mechanism.

Methods: We utilized the public datasets of SSc skin tissue from the Gene Expression Omnibus (GEO) database to analyze the expression and clinical significance of integrin family genes in SSc. The expression of integrin members in skin tissue was also assessed by immunohistochemistry. In addition, functional enrichment and pathway analysis were conducted.

Results: Compared with healthy controls, the mRNA and protein levels of ITGA5, ITGB2, and ITGB5 were upregulated in the skin of SSc patients. Further analysis indicated that the mRNA expression levels of ITGA5, ITGB2, and ITGB5 were positively correlated with modified Rodnan skin thickness score (mRSS). Functional enrichment and pathway analysis showed that integrin members may play multiple roles in the pathogenesis of SSc. Among them, ITGA5, ITGB2, and ITGB5 might synergistically promote SSc through affecting extracellular matrix (ECM) turnover, ECM–receptor interaction, focal adhesion, and leukocyte trans-endothelial migration, while ITGA5 and ITGB5 also might affect angiogenesis and endothelial cell function. In addition, ITGA5, ITGB2, and ITGA5 were associated with different pathways, respectively. ITGA5 was uniquely enriched for actin organization, while ITGB5 was for TGF-β signaling and ITGB2 for immune cell activation.

Conclusion: Our results implied that the abnormal expression of integrin family genes including ITGA5, ITGB2, and ITGB5 may participate in multiple pathological processes in SSc. Further investigations are required for confirming this speculation.

Crucial Role of Mammalian Glutaredoxin 3 in Cardiac Energy Metabolism in Diet-induced Obese Mice Revealed by Transcriptome Analysis

Obesity is often associated with metabolic dysregulation and oxidative stress with the latter serving as a possible unifying link between obesity and cardiovascular complications. Glutaredoxins (Grxs) comprise one of the major antioxidant systems in the heart. Although Grx3 has been shown to act as an endogenous negative regulator of cardiac hypertrophy and heart failure, its metabolic impact on cardiac function in diet-induced obese (DIO) mice remains largely unknown. In the present study, analysis of Grx3 expression indicated that Grx3 protein levels, but not mRNA levels, were significantly increased in the hearts of DIO mice. Cardiac-specific Grx3 deletion (Grx3 CKO) mice were viable and grew indistinguishably from their littermates after being fed a high fat diet (HFD) for one month, starting at 2 months of age. After being fed with a HFD for 8 months (starting at 2 months of age); however, Grx3 CKO DIO mice displayed left ventricular systolic dysfunction with a significant decrease in ejection fraction and fractional shortening that was associated with heart failure. ROS production was significantly increased in Grx3 CKO DIO cardiomyocytes compared to control cells. Gene expression analysis revealed a significant decline in the level of transcripts corresponding to genes associated with processes such as fatty acid uptake, mitochondrial fatty acid transport and oxidation, and citrate cycle in Grx3 CKO DIO mice compared to DIO controls. In contrast, an increase in the level of transcripts corresponding to genes associated with glucose uptake and utilization were found in Grx3 CKO DIO mice compared to DIO controls. Taken together, these findings indicate that Grx3 may play a critical role in redox balance and as a metabolic switch in cardiomyocytes contributing to the development and progression of heart failure.