TRIM72 contributes to cardiac fibrosis via regulating STAT3/Notch-1 signaling

MG53 protects against Coxsackievirus B3-induced acute viral myocarditis in mice by inhibiting NLRP3 inflammasome-mediated pyroptosis via the NF-κB signaling pathway

Pyroptosis, a novel programmed cell death mediated by NOD-like receptor protein 3 (NLRP3) inflammasome, is a critical pathogenic process in acute viral myocarditis (AVMC). Mitsugumin 53 (MG53) is predominantly expressed in myocardial tissues and has been reported to exert cardioprotective effects through multiple pathways. Herein, we aimed to investigate the biological function of MG53 in AVMC and its underlying regulatory mechanism in pyroptosis. BALB/c mice and HL-1 cells were infected with Coxsackievirus B3 (CVB3) to establish animal and cellular models of AVMC. As inflammation progressed in the myocardium, we found a progressive decrease in myocardial MG53 expression, accompanied by a significant enhancement of cardiomyocyte pyroptosis. MG53 overexpression significantly alleviated myocardial inflammation, apoptosis, fibrosis, and mitochondrial damage, thereby improving cardiac dysfunction in AVMC mice. Moreover, MG53 overexpression inhibited NLRP3 inflammasome-mediated pyroptosis, reduced pro-inflammatory cytokines (IL-1β/18) release, and suppressed NF-κB signaling pathway activation both in vivo and in vitro. Conversely, MG53 knockdown reduced cell viability, facilitated cell pyroptosis, and increased pro-inflammatory cytokines release in CVB3-infected HL-1 cells by promoting NF-κB activation. These effects were partially reversed by applying the NF-κB inhibitor BAY 11-7082. In conclusion, our results suggest that MG53 acts as a negative regulator of NLRP3 inflammasome-mediated pyroptosis in CVB3-induced AVMC, partially by inhibiting the NF-κB signaling pathway. MG53 is a promising candidate for clinical applications in AVMC treatment.

JAK/STAT3 signaling in cardiac fibrosis: a promising therapeutic target

Cardiac fibrosis is a serious health problem because it is a common pathological change in almost all forms of cardiovascular diseases. Cardiac fibrosis is characterized by the transdifferentiation of cardiac fibroblasts (CFs) into cardiac myofibroblasts and the excessive deposition of extracellular matrix (ECM) components produced by activated myofibroblasts, which leads to fibrotic scar formation and subsequent cardiac dysfunction. However, there are currently few effective therapeutic strategies protecting against fibrogenesis. This lack is largely because the molecular mechanisms of cardiac fibrosis remain unclear despite extensive research. The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling cascade is an extensively present intracellular signal transduction pathway and can regulate a wide range of biological processes, including cell proliferation, migration, differentiation, apoptosis, and immune response. Various upstream mediators such as cytokines, growth factors and hormones can initiate signal transmission via this pathway and play corresponding regulatory roles. STAT3 is a crucial player of the JAK/STAT pathway and its activation is related to inflammation, malignant tumors and autoimmune illnesses. Recently, the JAK/STAT3 signaling has been in the spotlight for its role in the occurrence and development of cardiac fibrosis and its activation can promote the proliferation and activation of CFs and the production of ECM proteins, thus leading to cardiac fibrosis. In this manuscript, we discuss the structure, transactivation and regulation of the JAK/STAT3 signaling pathway and review recent progress on the role of this pathway in cardiac fibrosis. Moreover, we summarize the current challenges and opportunities of targeting the JAK/STAT3 signaling for the treatment of fibrosis. In summary, the information presented in this article is critical for comprehending the role of the JAK/STAT3 pathway in cardiac fibrosis, and will also contribute to future research aimed at the development of effective anti-fibrotic therapeutic strategies targeting the JAK/STAT3 signaling.

Transcriptional response of the heart to vagus nerve stimulation

Heart failure is a major clinical problem, with treatments involving medication, devices, and emerging neuromodulation therapies such as vagus nerve stimulation (VNS). Considering the ongoing interest in using VNS to treat cardiovascular disease, it is important to understand the genetic and molecular changes developing in the heart in response to this form of autonomic neuromodulation. This experimental animal (rat) study investigated the immediate transcriptional response of the ventricular myocardium to selective stimulation of vagal efferent activity using an optogenetic approach. Vagal preganglionic neurons in the dorsal motor nucleus of the vagus nerve were genetically targeted to express light-sensitive chimeric channelrhodopsin variant ChIEF and stimulated using light. RNA sequencing of the left ventricular myocardium identified 294 differentially expressed genes (false discovery rate < 0.05). Qiagen Ingenuity Pathway Analysis (IPA) highlighted 118 canonical pathways that were significantly modulated by vagal activity, of which 14 had a z score of ≥2/≤-2, including EIF-2, IL-2, integrin, and NFAT-regulated cardiac hypertrophy. IPA revealed the effect of efferent vagus stimulation on protein synthesis, autophagy, fibrosis, autonomic signaling, inflammation, and hypertrophy. IPA further predicted that the identified differentially expressed genes were the targets of 50 upstream regulators, including transcription factors (e.g., MYC and NRF1) and microRNAs (e.g., miR-335-3p and miR-338-3p). These data demonstrate that the vagus nerve has a major impact on the myocardial expression of genes involved in the regulation of key biological pathways. The transcriptional response of the ventricular myocardium induced by stimulation of vagal efferents is consistent with the beneficial effect of maintained/increased vagal activity on the heart.NEW & NOTEWORTHY This experimental animal study investigated the immediate transcriptional response of the ventricular myocardium to selective stimulation of vagal efferent activity. Vagal stimulation induced significant transcriptional changes in the heart involving the pathways controlling autonomic signaling, inflammation, fibrosis, and hypertrophy. This study provides the first direct evidence that myocardial gene expression is modulated by the activity of the autonomic nervous system.

Advances in the Study of MG53 in Cardiovascular Disease

Cardiovascular diseases represent a global health crisis, and understanding the intricate molecular mechanisms underlying cardiac pathology is crucial for developing effective diagnostic and therapeutic strategies. Mitsugumin-53 (MG53) plays a pivotal role in cell membrane repair, has emerged as a multifaceted player in cardiovascular health. MG53, also known as TRIM72, is primarily expressed in cardiac and skeletal muscle and actively participates in membrane repair processes essential for maintaining cardiomyocyte viability. It promotes k-ion currents, ensuring action potential integrity, and actively engages in repairing myocardial and mitochondrial membranes, preserving cardiac function in the face of oxidative stress. This study discusses the dual impact of MG53 on cardiac health, highlighting its cardioprotective role during ischemia/reperfusion injury, its modulation of cardiac arrhythmias, and its influence on cardiomyopathy. MG53's regulation of metabolic pathways, such as lipid metabolism, underlines its role in diabetic cardiomyopathy, while its potential to mitigate the effects of various cardiac disorders, including those induced by antipsychotic medications and alcohol consumption, warrants further exploration. Furthermore, we examine MG53's diagnostic potential as a biomarker for cardiac injury. Research has shown that MG53 levels correlate with cardiomyocyte damage and may predict major adverse cardiovascular events, highlighting its value as a biomarker. Additionally, exogenous recombinant human MG53 (rhMG53) emerges as a promising therapeutic option, demonstrating its ability to reduce infarct size, inhibit apoptosis, and attenuate fibrotic responses. In summary, MG53's diagnostic and therapeutic potential in cardiovascular diseases presents an exciting avenue for improved patient care and outcomes.

Andrographolide contributes to the attenuation of cardiac hypertrophy by suppressing endoplasmic reticulum stress

CONTEXT

Andrographolide (Andr) is a bioactive Andr diterpenoid extracted from herbaceous Andrographis paniculata (Burm. F.) Wall. ex Nees (Acanthaceae). Andr can relieve cardiac dysfunction in mice by inhibiting the mitogen-activated protein kinases (MAPK) pathway.

OBJECTIVE

This study investigates the efficacy and underlying mechanism of Andr on cardiac hypertrophy in mice.

MATERIALS AND METHODS

Male C57 mice (20-25 g, 6-8 weeks) were divided into four groups (n = 10 mice/group) as sham group (sham operation), transverse aortic constriction (TAC) model group, TAC + Andr 100 mg/kg group and TAC + Andr 200 mg/kg group. Andr groups were given intragastric administration of Andr (100 and 200 mg/kg) once a day for 14 consecutive days. An in vitro hypertrophy model was established by adding 1 μM of Ang II to H9c2 cells for 48 h induction.

RESULTS

In TAC-mice, Andr improved echocardiographic indices [reduced LVESD (30.4% or 37.1%) and LVEDD (24.8% or 26.4%), increased EF (22.9% or 42.6%) and FS (25.4% or 52.2%)], reduced BNP (11.5% or 23.6%) and Ang II levels (10.3% or 32.8%), attenuates cardiac fibrosis and reduces cardiac cell apoptosis in TAC mice. In vitro, Andr attenuated cardiomyocyte hypertrophy and decreased the protein expression of GRP78 (67.8%), GRP94 (47.6%), p-PERK (44.9%) and CHOP (66.8%) in Ang-II-induced H9c2 cells and reversed after endoplasmic reticulum (ER) stress agonist Tunicamycin (TN) treatment.

DISCUSSION AND CONCLUSIONS

Andr was found to be an anti-hypertrophic regulator, which could attenuate cardiac hypertrophy by suppressing ER stress. It may be a new therapeutic drug for cardiac hypertrophy.

Is MG53 a potential therapeutic target for cancer?

Cancer treatment still encounters challenges, such as side effects and drug resistance. The tripartite-motif (TRIM) protein family is widely involved in regulation of the occurrence, development, and drug resistance of tumors. MG53, a member of the TRIM protein family, shows strong potential in cancer therapy, primarily due to its E3 ubiquitin ligase properties. The classic membrane repair function and anti-inflammatory capacity of MG53 may also be beneficial for cancer prevention and treatment. However, MG53 appears to be a key regulatory factor in impaired glucose metabolism and a negative regulatory mechanism in muscle regeneration that may have a negative effect on cancer treatment. Developing MG53 mutants that balance the pros and cons may be the key to solving the problem. This article aims to summarize the role and mechanism of MG53 in the occurrence, progression, and invasion of cancer, focusing on the potential impact of the biological function of MG53 on cancer therapy.

Salsolinol improves angiotensin II‑induced myocardial fibrosis in vitro via inhibition of LSD1 through regulation of the STAT3/Notch‑1 signaling pathway

The clinical incidence of congestive heart failure (CHF) is very high and it poses a significant threat to the health of patients. The traditional Chinese medicine monomer salsolinol is widely used to treat similar symptoms of CHF. However, there have been no reports on the effect of salsolinol for the management of CHF and its effects on myocardial fibrosis. In the present study, salsolinol was used to treat angiotensin II (AngII)-induced human cardiac fibroblasts (HCFs) and cell proliferation and migration were assessed using a CCK-8, EdU staining assay and wound healing assay. Subsequently, immunofluorescence, western blotting and other techniques were used to detect indicators associated with cell fibrosis and relevant kits were used to detect markers of cellular inflammation and reactive oxygen species (ROS) production. Molecular docking analysis was used to predict the relationship between salsolinol and lysine-specific histone demethylase 1A (LSD1). Subsequently, the expression of LSD1 in the serum of CHF patients was detected by reverse transcription-quantitative PCR. Finally, LSD1 was overexpressed in cells to explore the regulatory mechanism of salsolinol in AngII-induced HFCs. Salsolinol reduced the proliferation and migration. Salsolinol reduced the expression of fibrosis marker proteins α-smooth muscle actin, Collagen I and Collagen III in a concentration-dependent manner, thereby reducing cell fibrosis. In addition, salsolinol reduced the levels of TNF-α and IL-6 in the cell supernatant and ROS production following AngII induction. Salsolinol inhibited LSD1 expression and regulated the STAT3/Notch-1 signaling pathway. Upregulation of LSD1 reversed the effects of salsolinol on AngII-induced HCFs. Salsolinol inhibited LSD1 via regulation of the STAT3/Notch-1 signaling pathway to improve Ang II-induced myocardial fibrosis in vitro.

MG53 does not mark cardiovascular risk and all-cause mortality in subjects with type 2 diabetes: A prospective, observational study

AIMS

Subjects with type 2 diabetes (T2D) are characterized by a high cardiovascular morbidity and mortality. MG53, a marker of peripheral insulin resistance, has been linked with impaired β-cell function and decreased β-cell survival, and its circulating levels are increased in T2D. Its relationship with the cardiovascular risk profile and mortality in T2D is currently unknown.

METHODS

In this longitudinal study, MG53 was measured in serum samples collected at baseline for 296 Caucasian participants in the MIND.IT study, relating its circulating levels with the cardiovascular risk profile and all-cause mortality over a 17-years follow up.

RESULTS

As compared to a reference cohort of 234 healthy subjects, MG53 levels were higher in T2D individuals (p < 0.001), and higher in T2D women than in men (p = 0.001). In the whole study cohort, MG53 levels were directly related to HbA1c (r2 0.029; p = 0.006) and systolic blood pressure (r2 0.032; p = 0.004). There was no difference in baseline MG53 levels between deceased and alive participants, neither predict all-cause mortality.

CONCLUSIONS

MG53 does not mark the cardiovascular risk profile neither predict long-term mortality in Caucasian T2D individuals.

Nucleosome assembly protein 1 like 1 (NAP1L1) promotes cardiac fibrosis by inhibiting YAP1 ubiquitination and degradation

Myocardial fibrosis post myocardial infarction (MI) is characterized by abnormal extracellular matrix (ECM) deposition and cardiac dysfunction could finally develop into serious heart disease, like heart failure. Lots of regulating factors involved in this pathological process have been reported while the specific mediators and underlying mechanisms remain to need to be further investigated. As part of the NAP1 family, Nucleosome assembly protein 1 like 1 (NAP1L1) is expressed in a wide variety of tissues. Here, we report that NAP1L1 is a significant regulator of cardiac fibrosis and is upregulated in ischemic cardiomyopathy patient hearts. Enhanced expression of NAP1L1 can promote cardiac fibroblasts (CFs) proliferation, migration, and differentiation into myofibroblasts. In contrast, loss of NAP1L1 decreased fibrosis-related mRNA and protein levels, inhibited the trans-differentiation, and blunted migration and proliferation of CFs after Transforming Growth Factorβ1（TGF-β1）stimulation. In vivo, NAP1L1 knockout mice enhanced cardiac function and reduced fibrosis area in response to MI stimuli. Mechanically, NAP1L1 binding to Yes-associated protein 1 (YAP1) protein influences its stability, and silencing NAP1L1 can inhibit YAP1 expression by promoting its ubiquitination and degradation in CFs. Collectively, NAP1L1 could potentially be a new therapeutic target for various cardiac disorders, including myocardial fibrosis.

TRIM44 aggravates cardiac fibrosis after myocardial infarction via TAK1 stabilization

Myocardial infarction (MI) is one of the most dangerous cardiovascular events. Cardiac fibrosis is a common pathological feature of remodeling after injury that is related to adverse clinical results with no effective treatment. Previous studies have confirmed that TRIM44, an E3 ligase, can promote the proliferation and migration of various tumor cells. However, the role of TRIM44 in cardiac fibrosis remains unknown. Models of TGF-β1 stimulation and MI-induced fibrosis were established to investigate the role and potential underlying mechanism of TRIM44 in cardiac fibrosis. The results showed that cardiac fibrosis was significantly inhibited after TRIM44 knockdown in a mouse model of MI, while it was enhanced when TRIM44 was overexpressed. Furthermore, in vitro studies showed that fibrosis markers were significantly reduced in cardiac fibroblasts (CFs) with TRIM44 knockdown, whereas TRIM44 overexpression promoted the expression of fibrosis markers. Mechanistically, TRIM44 maintains TAK1 stability by inhibiting the degradation of k48-linked polyubiquitination-mediated ubiquitination, thereby increasing phosphorylated TAK1 expression in the fibrotic environment and activating MAPKs to promote fibrosis. Pharmacological inhibition of TAK1 phosphorylation reversed the fibrogenic effects of TRIM44 overexpression. Combined, these results suggest that TRIM44 is a potential therapeutic target for cardiac fibrosis.

Potentilla anserina polysaccharide alleviates cadmium-induced oxidative stress and apoptosis of H9c2 cells by regulating the MG53-mediated RISK pathway

Oxidative stress plays a crucial role in cadmium (Cd)-induced myocardial injury. Mitsugumin 53 (MG53) and its mediated reperfusion injury salvage kinase (RISK) pathway have been demonstrated to be closely related to myocardial oxidative damage. Potentilla anserina L. polysaccharide (PAP) is a polysaccharide with antioxidant capacity, which exerts protective effect on Cd-induced damage. However, it remains unknown whether PAP can prevent and treat Cd-induced cardiomyocyte damages. The present study was desgined to explore the effect of PAP on Cd-induced damage in H9c2 cells based on MG53 and the mediated RISK pathway. For in vitro evaluation, cell viability and apoptosis rate were analyzed by CCK-8 assay and flow cytometry, respectively. Furthermore, oxidative stress was assessed by 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) staining and using superoxide dismutase (SOD), catalase (CAT), and glutathione/oxidized glutathione (GSH/GSSG) kits. The mitochondrial function was measured by JC-10 staining and ATP detection assay. Western blot was performed to detect the expression of proteins related to MG53, the RISK pathway, and apoptosis. The results indicated that Cd increased the levels of reactive oxygen species (ROS) in H9c2 cells. Cd decreased the activities of SOD and CAT and the ratio of GSH/GSSG, resulting in decreases in cell viability and increases in apoptosis. Interestingly, PAP reversed Cd-induced oxidative stress and cell apoptosis. Meanwhile, Cd reduced the expression of MG53 in H9c2 cells and inhibited the RISK pathway, which was mediated by decreasing the ratio of p-Akt^Ser473/Akt, p-GSK3β^Ser9/GSK3β and p-ERK1/2/ERK1/2. In addition, Cd impaired mitochondrial function, which involved a reduction in ATP content and mitochondrial membrane potential (MMP), and an increase in the ratio of Bax/Bcl-2, cytoplasmic cytochrome c/mitochondrial cytochrome c, and Cleaved-Caspase 3/Pro-Caspase 3. Importantly, PAP alleviated Cd-induced MG53 reduction, activated the RISK pathway, and reduced mitochondrial damage. Interestingly, knockdown of MG53 or inhibition of the RISK pathway attenuated the protective effect of PAP in Cd-induced H9c2 cells. In sum, PAP reduces Cd-induced damage in H9c2 cells, which is mediated by increasing MG53 expression and activating the RISK pathway.

F-box and WD repeat domain containing 7 inhibits the activation of hepatic stellate cells by degrading delta-like ligand 1 to block Notch signaling pathway

Hepatic fibrosis (HF) is a precursor of liver cirrhosis, and activated hepatic stellate cells are an important driver of fibrosis. F-box and WD repeat domain containing 7 (FBXW7) expression level is down-regulated in HF, but the underlying mechanism is yet to be elucidated. The interaction between FBXW7 and delta-like ligand 1 (DLL1) was predicted. LX-2 cells were subjected to transfection of FBXW7/DLL1 silencing or overexpression plasmid. The expressions of FBXW7 and DLL1 in HF in vitro were measured by quantitative reverse transcription polymerase chain reaction and western blot. The LX-2 cell cycle, viability, proliferation, and ubiquitination were determined by flow cytometry, cell counting kit-8, colony formation, and ubiquitination assays, respectively. FBXW7 overexpression suppressed the cell viability and proliferation, facilitated cell cycle arrest, and down-regulated α-smooth muscle actin (α-SMA), Collagen I, and DLL1 protein levels, but FBXW7 silencing did the opposite. DLL1 was bound to and ubiquitin-dependently degraded by FBXW7 overexpression. DLL1 overexpression promoted the cell viability and proliferation, accelerated cell cycle, and up-regulated the levels of α-SMA, Collagen I, NOTCH2, NOTCH3, and HES1, but these trends were reversed by FBXW7 overexpression. To sum up, FBXW7 overexpression suppresses the progression of HF in vitro by ubiquitin-dependently degrading DLL1.

Activation of PPARα Ameliorates Cardiac Fibrosis in Dsg2-Deficient Arrhythmogenic Cardiomyopathy

Highlights

Abstract

Background: Arrhythmogenic cardiomyopathy (ACM) is a genetic heart muscle disease characterized by progressive fibro-fatty replacement of cardiac myocytes. Up to now, the existing therapeutic modalities for ACM are mostly palliative. About 50% of ACM is caused by mutations in genes encoding desmosomal proteins including Desmoglein-2 (Dsg2). In the current study, the cardiac fibrosis of ACM and its underlying mechanism were investigated by using a cardiac-specific knockout of Dsg2 mouse model. Methods: Cardiac-specific Dsg2 knockout (CS-Dsg2^−/−) mice and wild-type (WT) mice were respectively used as the animal model of ACM and controls. The myocardial collagen volume fraction was determined by histological analysis. The expression levels of fibrotic markers such as α-SMA and Collagen I as well as signal transducers such as STAT3, SMAD3, and PPARα were measured by Western blot and quantitative real-time PCR. Results: Increased cardiac fibrosis was observed in CS-Dsg2^−/− mice according to Masson staining. PPARα deficiency and hyperactivation of STAT3 and SMAD3 were observed in the myocardium of CS-Dsg2^−/− mice. The biomarkers of fibrosis such as α-SMA and Collagen I were upregulated after gene silencing of Dsg2 in HL-1 cells. Furthermore, STAT3 gene silencing by Stat3 siRNA inhibited the expression of fibrotic markers. The activation of PPARα by fenofibrate or AAV9-Pparα improved the cardiac fibrosis and decreased the phosphorylation of STAT3, SMAD3, and AKT in CS-Dsg2^−/− mice. Conclusions: Activation of PPARα alleviates the cardiac fibrosis in ACM.

Hypoxia-induced mesenchymal stem cells inhibit corneal fibroblast proliferation by regulating the WWP2/Notch1 axis

Aim: This study aimed to explore the role of hypoxic mesenchymal stem cells (MSCs) in corneal alkali burns and the underlying mechanism. Materials & methods: Rat corneal fibroblasts were incubated with IL-6, followed by treatment with hypoxic MSC supernatant. A rat corneal alkali burn model was implemented and processed with hypoxic MSCs. The associated factors were detected by corresponding methods. Results: Hypoxic MSCs reduced the Notch1 level and the proliferation of rat corneal fibroblasts. Hypoxic MSCs or WWP2 overexpression in MSCs enhanced ubiquitination of Notch1. WWP2 interacted with Notch1, and WWP2 silencing reversed the effects of the hypoxic MSCs. Hypoxic MSC treatment in vivo decreased the corneal neovascularization scores and opacity scores. Conclusion: Hypoxic MSCs inhibited inflammation and alleviated corneal injury in alkali burns via the WWP2/Notch1 axis.

FSTL1-USP10-Notch1 Signaling Axis Protects Against Cardiac Dysfunction Through Inhibition of Myocardial Fibrosis in Diabetic Mice

The incidence of type 2 diabetes mellitus (T2DM) has been increasing globally, and T2DM patients are at an increased risk of major cardiac events such as myocardial infarction (MI). Nevertheless, the molecular mechanisms underlying MI injury in T2DM remain elusive. Ubiquitin-specific protease 10 (USP10) functions as a NICD1 (Notch1 receptor) deubiquitinase that fine-tunes the essential myocardial fibrosis regulator Notch signaling. Follistatin-like protein 1 (FSTL1) is a cardiokine with proven benefits in multiple pathological processes including cardiac fibrosis and insulin resistance. This study was designed to examine the roles of FSTL1/USP10/Notch1 signaling in MI-induced cardiac dysfunction in T2DM. High-fat-diet-treated, 8-week-old C57BL/6J mice and db/db T2DM mice were used. Intracardiac delivery of AAV9-FSTL1 was performed in T2DM mice following MI surgery with or without intraperitoneal injection of crenigacestat (LY3039478) and spautin-1. Our results demonstrated that FSTL1 improved cardiac function following MI under T2DM by reducing serum lactate dehydrogenase (LDH) and myocardial apoptosis as well as cardiac fibrosis. Further in vivo studies revealed that the protective role of FSTL1 against MI injury in T2DM was mediated by the activation of USP10/Notch1. FSTL1 protected cardiac fibroblasts (CFs) against DM-MI-induced cardiofibroblasts injury by suppressing the levels of fibrosis markers, and reducing LDH and MDA concentrations in a USP10/Notch1-dependent manner. In conclusion, FSTL1 treatment ameliorated cardiac dysfunction in MI with co-existent T2DM, possibly through inhibition of myocardial fibrosis and apoptosis by upregulating USP10/Notch1 signaling. This finding suggests the clinical relevance and therapeutic potential of FSTL1 in T2DM-associated MI and other cardiovascular diseases.

TRIM proteins in fibrosis

Fibrosis is an outcome of tissue repair after different types of injuries. The homeostasis of extracellular matrix is broken, and excessive deposition occurs, affecting the normal function of tissues and organs, which could become prostrated in serious cases.Finding a suitable target to regulate the repair process and reduce the damage caused by fibrosis is a hot research topic at present. The TRIM family is number of one of the E3 ubiquitin ligase subfamilies and participates in various biological processes including intracellular signal transduction, apoptosis, autophagy, and immunity by regulating the ubiquitination of target proteins. For the past few years, the important role of TRIM in the occurrence and development of fibrosis has been gradually revealed. In this review, we focus on the recent emerging topics on TRIM proteins in the regulation of fibrosis, fibrosis-related cytokines and pathways.

Activation of the M3AChR and Notch1/HSF1 Signaling Pathway by Choline Alleviates Angiotensin II-Induced Cardiomyocyte Apoptosis

Angiotensin II- (Ang II-) induced cardiac hypertrophy and apoptosis are major characteristics of early-stage heart failure. Choline exerts cardioprotective effects; however, its effects on Ang II-induced cardiomyocyte apoptosis are unclear. In this study, the role and underlying mechanism of choline in regulating Ang II-induced cardiomyocyte apoptosis were investigated using a model of cardiomyocyte apoptosis, which was induced by exposing neonatal rat cardiomyocytes to Ang II (10⁻⁶ M, 48 h). Choline promoted heat shock transcription factor 1 (HSF1) nuclear translocation and the intracellular domain of Notch1 (NICD) expression. Consequently, choline attenuated Ang II-induced increases in mitochondrial reactive oxygen species (mtROS) and promotion of proapoptotic protein release from mitochondria, including cytochrome c, Omi/high-temperature requirement protein A2, and second mitochondrial activator of caspases/direct inhibitor of apoptosis-binding protein with low P. The reversion of these events attenuated Ang II-induced increases in cardiomyocyte size and numbers of terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling-positive cells, presumably via type 3 muscarinic acetylcholine receptor (M3AChR). Indeed, downregulation of M3AChR or Notch1 blocked choline-mediated upregulation of NICD and nuclear HSF1 expression, as well as inhibited mitochondrial apoptosis pathway and cardiomyocyte apoptosis, indicating that M3AChR and Notch1/HSF1 activation confer the protective effects of choline. In vivo studies were performed in parallel, in which rats were infused with Ang II for 4 weeks to induce cardiac apoptosis. The results showed that choline alleviated cardiac remodeling and apoptosis of Ang II-infused rats in a manner related to activation of the Notch1/HSF1 pathway, consistent with the in vitro findings. Taken together, our results reveal that choline impedes oxidative damage and cardiomyocyte apoptosis by activating M3AChR and Notch1/HSF1 antioxidant signaling, and suggest a novel role for the Notch1/HSF1 signaling pathway in the modulation of cardiomyocyte apoptosis.

Role of the microRNA-29 family in myocardial fibrosis

Myocardial fibrosis (MF) is an inevitable pathological process in the terminal stage of many cardiovascular diseases, often leading to serious cardiac dysfunction and even death. Currently, microRNA-29 (miR-29) is thought to be a novel diagnostic and therapeutic target of MF. Understanding the underlying mechanisms of miR-29 that regulate MF will provide a new direction for MF therapy. In the present review, we concentrate on the underlying signaling pathway of miR-29 affecting MF and the crosstalk regulatory relationship among these pathways to illustrate the complex regulatory network of miR-29 in MF. Additionally, based on our mechanistic understanding, we summarize opportunities and challenges of miR-29-based MF diagnosis and therapy.

Cardiac effects and clinical applications of MG53

Heart disease remains the leading cause of mortality globally, so further investigation is required to identify its underlying mechanisms and potential targets for treatment and prevention. Mitsugumin 53 (MG53), also known as TRIM72, is a TRIM family protein that was found to be involved in cell membrane repair and primarily found in striated muscle. Its role in skeletal muscle regeneration and myogenesis has been well documented. However, accumulating evidence suggests that MG53 has a potentially protective role in heart tissue, including in ischemia/reperfusion injury of the heart, cardiomyocyte membrane injury repair, and atrial fibrosis. This review summarizes the regulatory role of MG53 in cardiac tissues, current debates regarding MG53 in diabetes and diabetic cardiomyopathy, as well as highlights potential clinical applications of MG53 in treating cardiac pathologies.

C188-9 reduces TGF-β1-induced fibroblast activation and alleviates ISO-induced cardiac fibrosis in mice

Cardiac fibrosis is the final event of heart failure and is associated with almost all forms of cardiovascular disease. Cardiac fibroblasts (CFs), a major cell type in the heart, are responsible for regulating normal myocardial function and maintaining extracellular matrix homeostasis in adverse myocardial remodeling. In this study, we found that C188‐9, a small‐molecule inhibitor of signal transducer and activator of transcription 3 (STAT3), exhibited an antifibrotic function, both in vitro and in vivo. C188‐9 decreased transforming growth factor‐β1‐induced CF activation and fibrotic gene expression. Moreover, C188‐9 treatment alleviated heart injury and cardiac fibrosis in an isoproterenol‐induced mouse model by suppressing STAT3 phosphorylation and activation. These findings may help us better understand the role of C188‐9 in cardiac fibrosis and facilitate the development of new treatments for cardiac fibrosis and other cardiovascular diseases.

[Yanghe Pingchuan granule promotes BMSCs homing in asthmatic rats by upregulating miR-139-5p and downregulating Notch1/Hes1 pathway]

OBJECTIVE

To observe the effect of Yanghe Pingchuan (YHPC) granule on miR-139-5p, Notch1/Hes1 pathway and homing of bone marrow-derived mesenchymal stem cells (BMSCs) in asthmatic rats.

METHODS

Fifty SD rats were randomized divided into normal control (NC) group, asthmatic model group, BMSCs transplantation group, BMSCs + dexamethasone (0.0625 mg/kg daily) group, and BMSCs+YHPC granule (3.5 g/kg daily) group. In all but the normal control group, asthmatic rat models were established by ovalbumin challenge, and BMSCs (1×10⁶/mL) transplantation via the tail vein was performed in the latter 3 groups on last day of ovalbumin challenge. In all the groups, lung pathologies of the rats were evaluated using HE staining after the treatments. Flow cytometry was employed to detect pulmonary expression of CXCR4 protein, and ELISA was used to determine the expressions of interferon-γ (IFN-γ) and interleukin-4 (IL-4) in the lung tissue. The expressions of CXCR4, Notch1 and Hes1 in bronchial epithelial cells was examined using immunofluorescence assay. RT-PCR was used to detect the expressions of miR-139-5p, Notch1, Jagged1, RBP-J and Hes1 mRNAs, and the protein expressions of Notch1, Jagged1 and Hes1 were detected with Western blotting.

RESULTS

Compared with the normal control rats, the asthmatic rats exhibited significantly increased expressions of CXCR4, IL-4, Notch1, Jagged1, RBP-J, and Hes1 mRNA and Notch1, Jagged1, and Hes1 proteins and lowered expressions of INF-γ mRNA and miR-139-5p in the lung tissues (P < 0.05 or 0.01). Compared with those in the asthmatic model group, the mRNA expressions of CXCR4, IFN-γ, and miR-139-5p increased and the expressions of IL-4, Notch1, Jagged1, RBP-J, and Hes1 mRNA and Notch1, Jagged1, and Hes1 proteins decreased significantly in the 3 groups with BMSCs transplantation (P < 0.05 or 0.01). The rats in BMSCs+YHPC granule group showed significantly higher CXCR4, IFN-γ, and miR-139-5p mRNA expressions and lower IL-4 and Notch1 mRNA expressions than those in BMSCs transplantation group (P < 0.05).

CONCLUSIONS

YHPC granule can enhance the inhibitory effect of BMSCs homing on Th2 inflammatory response in asthmatic rats by up-regulating miR-139-5p and down-regulating Notch1/Hes1 pathway.

TRIM72 mediates lung epithelial cell death upon hyperoxia exposure

BACKGROUND

Premature infants often require oxygen (O2) therapy for respiratory distress syndrome; however, excessive use of O2 can cause clinical conditions such as bronchopulmonary dysplasia. Although many treatment methods are currently available, they are not effective in preventing bronchopulmonary dysplasia. Herein, we explored the role of tripartite motif protein 72 (TRIM72), a factor involved in repairing alveolar epithelial wounds, in regulating alveolar cells upon hyperoxia exposure.

METHODS

In this in vivo study, we used Sprague-Dawley rat pups that were reared in room air or 85% O2 for 2 weeks after birth. The lungs were excised for histological analyses, and TRIM72 expression was assessed on postnatal days 7 and 14. For in vitro experiments, RLE-6TN cells (i.e., rat alveolar type II epithelial cells) and A549 cells (i.e., human lung carcinoma epithelial cells) were exposed to 85% O2 for 5 days. The cells were then analyzed for cell viability, and TRIM72 expression was determined.

RESULTS

Exposure to hyperoxia reduced body and lung weight, increased mean linear intercept values, and upregulated TRIM72 expression. In vitro study results revealed increased or decreased lung cell viability upon hyperoxia exposure depending on the suppression or overexpression of TRIM72, respectively.

CONCLUSION

Hyperoxia upregulates TRIM72 expression in neonatal rat lung tissue; moreover, it initiates TRIM72-dependent alveolar epithelial cell death, leading to hyperoxia-induced lung injury.

MG53/CAV1 regulates transforming growth factor-β1 signaling-induced atrial fibrosis in atrial fibrillation

Atrial fibrosis plays a significant role in the development of atrial fibrillation (AF). Previously, we showed that mitsugumin 53 (MG53) regulates TGF-β1 signaling pathway-induced atrial fibrosis. Recent studies have shown that caveolin-1 (CAV1) is an important anti-fibrosis signaling mediator that inhibits the TGF-β1 signaling pathway. Here, we further study the mechanism underlying the related action of MG53 and CAV1. We demonstrate that CAV1 expression was decreased while MG53 expression was increased in atrial tissue from AF patients. In cultured atrial fibroblasts, MG53 depletion by siRNA caused CAV1 upregulation and TGF-β1/SMAD2 signaling pathway downregulation, while MG53 overexpression via adenovirus had the opposite effect. CAV1 inactivated the TGF-β1/SMAD2 signaling pathway. In addition, using an Ang II-induced fibrosis model, we show that MG53 regulates TGF-β1 signaling via CAV1. Therefore, CAV1 is critical for the MG53 regulation of TGF-β1 signaling pathway-induced atrial fibrosis in AF. These findings reveal the related underlying mechanism of action of MG53 and CAV1 and provide a potential therapeutic target for fibrosis and AF.

The Pivotal Role of Mitsugumin 53 in Cardiovascular Diseases

The MG53 (also known as TRIM72) is a conserved, muscle-specific tripartite motif family protein that is abundantly expressed in cardiac or skeletal muscle and present in circulation. Recently, the MG53 had been hypothesized to serve a dual role in the heart: involving in repairing cell membranes that protect myocardial function while acting as an E3 ligase to trigger insulin resistance and cardiovascular complications. This review discusses the roles of MG53 in cardiac physiological function with emphasis on MG53 protective function in the heart and its negative impact on the myocardium due to the continuous elevation of MG53. Besides, this work reviewed the significance of MG53 as a potential therapeutic in human cardiovascular diseases. Despite the expression of MG53 being rare in the human, thus exogenous MG53 can potentially be a new treatment for human cardiovascular diseases. Notably, the specific mechanism of MG53 in cardiovascular diseases remains elusive.

Adipose mesenchymal stem cell transplantation alleviates spinal cord injury-induced neuroinflammation partly by suppressing the Jagged1/Notch pathway

BACKGROUND

The therapeutic effects of adipose-derived mesenchymal stem cell (ADSC) transplantation have been demonstrated in several models of central nervous system (CNS) injury and are thought to involve the modulation of the inflammatory response. However, the exact underlying molecular mechanism is poorly understood. Activation of the Jagged1/Notch signaling pathway is thought to involve inflammatory and gliotic events in the CNS. Here, we elucidated the effect of ADSC transplantation on the inflammatory reaction after spinal cord injury (SCI) and the potential mechanism mediated by Jagged1/Notch signaling pathway suppression.

METHODS

To evaluate the therapeutic effects of ADSC treatment and the potential inhibitory effects of ADSCs on Notch signaling, mice were subjected to contusion SCI, and GFP-labeled ADSCs were injected into the lesion site immediately after the injury. Locomotor function, spinal cord tissue morphology, and the levels of Notch-related proteins and proinflammatory transcripts were compared between groups. To validate the hypothesis that the therapeutic effects of ADSCs are partly due to Notch1 signaling inhibition, a Jagged1 small interfering RNA (siRNA) was injected into the spinal cord to knock down Jagged1/Notch signaling. Neuronal staining and analyses of microglia/macrophage activation and signaling pathways were performed.

RESULTS

We demonstrated that ADSCs survived in the injured spinal cord for at least 28 days without differentiating into glial or neuronal elements. ADSC treatment resulted in significant downregulation of proinflammatory mediator expression and reduced ionized calcium-binding adapter molecule 1 (IBA1) and ED-1 staining in the injured spinal cord, eventually improving functional recovery. The augmentation of the Jagged1/Notch signaling pathway after SCI was suppressed by ADSC transplantation. The inhibition of the Jagged1/Notch signaling pathway by Jagged1 siRNA resulted in decreases in SCI-induced proinflammatory cytokines and the activation of microglia and an increase in the survival of neurons. Furthermore, Jagged1 knockdown suppressed the phosphorylation of JAK/STAT3 in astrocytes following SCI.

CONCLUSION

The results of this study demonstrated that the therapeutic effects of ADSCs in SCI mice were partly due to Jagged1/Notch signaling pathway inhibition and a subsequent reduction in JAK/STAT3 phosphorylation in astrocytes.

Anti-fibrotic effect of melittin on TRIM47 expression in human embryonic lung fibroblast through regulating TRIM47 pathway

AIMS

To investigate the effect and underlying mechanism of melittin and tripartite motif (TRIM) family in human embryonic lung fibroblast (HELF).

MATERIALS AND METHODS

Lentiviral RNA interference vector and lentiviral overexpression vector were constructed and packaged by transfecting 293T cells; the proliferation of HELF was examined using Cell Counting Kit 8; Western blot and qRT-PCR were performed to examine protein and mRNA expression; the interaction with protein phosphatase magnesium-dependent 1A (PPM1A) was examined by Co-immunoprecipitation.

KEY FINDINGS

Compared with the control group, the mRNA expression of the TRIM6, TRIM8 and TRIM47 in the IPF group significantly increased. Melittin inhibited the mRNA expression and protein expression levels of TRIM47, the HELF proliferation, the hydroxyproline levels, and the phosphorylation of Smad2/3; the interference of TRIM47 inhibited the protein expression of Vimentin, α-SMA, CTGF, the phosphorylation of Smad2/3 and the synthesis of hydroxyproline; TRIM47 overexpression elevated the phosphorylation of Smad2/3, induced ubiquitination of PPM1A and decreased the expression level of PPM1A, while TRIM47 RNA interference reversed this result.

SIGNIFICANCE

Melittin has anti-fibrotic effect in HELF by directly reducing the phosphorylation of Smad2/3 or indirectly reducing the phosphorylation of Smad2/3 by decreasing the expression levels of TRIM47 whose overexpression induces ubiquitination of PPM1A.

Si-Miao-Yong-An decoction attenuates cardiac fibrosis via suppressing TGF-β1 pathway and interfering with MMP-TIMPs expression

BACKGROUND

Myocardial fibrosis is an important pathological feature of pressure overload cardiac remodeling. Si-Miao-Yong-An decoction (SMYAD), a traditional Chinese formula, is now clinically used in the treatment of cardiovascular diseases in China. However, its mechanisms in the prevention of heart failure are not fully revealed.

PURPOSE

To determine whether treatment with SMYAD for 4 weeks would lead to changes in collagen metabolism and ventricular remodeling in a mice model of heart failure.

METHODS

Mice were subjected to transverse aorta constriction to generate pressure overload induced cardiac remodeling and then were administered SMYAD (14.85 g/kg/day) or captopril (16.5 mg/kg/day) intragastrically for 4 weeks after surgery. Echocardiography and immunohistochemical examination were used to evaluate the effects of SMYAD. The mRNA of collagen metabolism biomarkers were detected. Protein expression of TGF-β1/Smad and TGF-β1/TAK1/p38 pathway were assessed by Western blot.

RESULTS

SMYAD significantly improved cardiac function, increased left ventricle ejection fraction, and decreased fibrosis area and αSMA expression. Moreover, SMYAD reduced proteins expression related to collagen metabolism, including Col1, Col3, TIMP2 and CTGF. The increased levels of TGF-β1, Smad2, and Smad3 phosphorylation were attenuated in SMYAD group. In addition, SMYAD reduced the levels of TGF-β1, p-TAK1 and p-p38 compared with TAC group.

CONCLUSIONS

SMYAD improved cardiac fibrosis and heart failure by inhibition of TGF-β1/Smad and TGF-β1/TAK1/p38 pathway. SMYAD protected against cardiac fibrosis and maintained collagen metabolism balance by regulating MMP-TIMP expression. Taken together, these results indicate that SMYAD might be a promising therapeutic agent against cardiac fibrosis.

Emerging Role of TRIM Family Proteins in Cardiovascular Disease

Ubiquitination is one of the basic mechanisms of cell protein homeostasis and degradation and is accomplished by 3 enzymes, E1, E2, and E3. Tripartite motif-containing proteins (TRIMs) constitute the largest subfamily of RING E3 ligases, with >70 current members in humans and mice. These members are involved in multiple biological processes, including growth, differentiation, and apoptosis as well as disease and tumorigenesis. Accumulating evidence has shown that many TRIM proteins are associated with various cardiac processes and pathologies, such as heart development, signal transduction, protein degradation, autophagy mediation, ion channel regulation, congenital heart disease, and cardiomyopathies. In this review, we provide an overview of the TRIM family and discuss its involvement in the regulation of cardiac proteostasis and pathophysiology and its potential therapeutic implications.

The regulatory role of Myomaker and Myomixer-Myomerger-Minion in muscle development and regeneration

Skeletal muscle plays essential roles in motor function, energy, and glucose metabolism. Skeletal muscle formation occurs through a process called myogenesis, in which a crucial step is the fusion of mononucleated myoblasts to form multinucleated myofibers. The myoblast/myocyte fusion is triggered and coordinated in a muscle-specific way that is essential for muscle development and post-natal muscle regeneration. Many molecules and proteins have been found and demonstrated to have the capacity to regulate the fusion of myoblast/myocytes. Interestingly, two newly discovered muscle-specific membrane proteins, Myomaker and Myomixer (also called Myomerger and Minion), have been identified as fusogenic regulators in vertebrates. Both Myomaker and Myomixer-Myomerger-Minion have the capacity to directly control the myogenic fusion process. Here, we review and discuss the latest studies related to these two proteins, including the discovery, structure, expression pattern, functions, and regulation of Myomaker and Myomixer-Myomerger-Minion. We also emphasize and discuss the interaction between Myomaker and Myomixer-Myomerger-Minion, as well as their cooperative regulatory roles in cell-cell fusion. Moreover, we highlight the areas for exploration of Myomaker and Myomixer-Myomerger-Minion in future studies and consider their potential application to control cell fusion for cell-therapy purposes.

LncRNA AK045171 protects the heart from cardiac hypertrophy by regulating the SP1/MG53 signalling pathway

Hearts often undergo abnormal remodelling and hypertrophic growth in response to pathological stress. Long non-coding RNAs (LncRNAs) can change cardiac function and participate in regulation of cardiac hypertrophy. The present study aims to identify the role of AK045171 in cardiac hypertrophy and the underlying mechanism in hypertrophic cascades. Mice with cardiac hypertrophy were established through transverse aortic constriction (TAC). Cardiac hypertrophy in cardiomyocytes was induced by angiotensin II (angII). The expression of AK045171 and its target gene SP1 was examined in cardiomyocytes transfected with miRNA. The AK045171 expression level was downregulated in mice after TAC surgery. Overexpression of AK045171 attenuated cardiac hypertrophy both in vitro and in vivo. The mechanism study indicated that AK045171 binds with SP1, which promotes transcription activation of MEG3. It is suggested that overexpression of AK045171 might have clinical potential to suppress cardiac hypertrophy and heart failure.

Tripartite motif protein 52 (TRIM52) promoted fibrosis in LX-2 cells through PPM1A-mediated Smad2/3 pathway

To investigate the roles of tripartite motif containing 52 (TRIM52) in human hepatic fibrosis in vitro, human hepatic stellate cell line LX-2 cells were transfected with hepatitis B virus (HBV) replicon to establish HBV-induced fibrosis in LX-2 cells, and then treated with small interfering RNA-mediated knockdown of TRIM52 (siTRIM52). LX-2 cells without HBV replicon transfection were treated with lentiviruses-mediated overexpression of TRIM52 and phosphatase magnesium dependent 1A (PPM1A). Fibrosis response of LX-2 cells were assessed by the production of hydroxyproline (Hyp) and collagen I/III, as well as protein levels of α-smooth muscle actin (α-SMA). PPM1A and phosphorylated (p)-Smad2/3 were measured to assess the mechanism. The correlation between TRIM52 and PPM1A was determined using co-immunoprecipitation, and whether and how TRIM52 regulated the degradation of PPM1A were determined by ubiquitination assay. Our data confirmed HBV-induced fibrogenesis of LX-2 cells, as evidenced by significant increase in Hyp and collagen I/III and α-SMA, which was associated with reduction of PPM1A and elevation of transforming growth factor-β (TGF-β), p-Smad2/3, and p-Smad3L. However, those changes induced by HBV were significantly attenuated with additional siTRIM52 treatment. Similar to HBV, overexpression of TRIM52 exerted promoted effect in the fibrosis of LX-2 cells. Interestingly, TRIM52 induced the fibrogenesis of LX-2 cells and the activation of TGF-β/Smad pathway were significantly reversed by PPM1A overexpression. Furthermore, our data confirmed TRIM52 as a deubiquitinase that influenced the accumulation of PPM1A protein, and subsequently regulated the fibrogenesis of LX-2 cells. TRIM52 was a fibrosis promoter in hepatic fibrosis in vitro, likely through PPM1A-mediated TGF-β/Smad pathway.

Blocking Notch signal pathway suppresses the activation of neurotoxic A1 astrocytes after spinal cord injury

Spinal cord injury (SCI) is a catastrophic disease which has complicated pathogenesis including inflammation, oxidative stress and glial scar formation. Astrocytes are the most abundant cells in central nervous system and fulfill homeostatic functions. Recent studies have described a new reactive phenotype of astrocytes, A1, induced by inflammation, which may have negative effects in SCI. As the Notch signaling pathway has been linked to cell differentiation and inflammation, we aimed to investigate its potential role in the differentiation of astrocytes in SCI. Contusive SCI rat model showed elevated A1 astrocyte numbers at the damage site 28 days after SCI and the expression levels of Notch signaling and its downstream genes were upregulated parallelly. Western blotting, RT-qPCR and immunofluorescence revealed that blocking of Notch pathway using γ-secretase blocker (DAPT) suppressed the differentiation of A1 astrocytes. Flow cytometry, and TUNEL staining indicated that DAPT alleviated neuronal apoptosis and axonal damage caused by A1 astrocytes likely through the Notch-dependent release of pro-inflammatory factors. CO-IP and western blotting revealed an interaction between Notch pathway and signal transducer and activator of transcription 3 (Stat3), which played a vital role in differentiation of A1 astrocytes. We conclude that phenotypic transition of A1 astrocytes and their neurotoxity were controlled by the Notch-Stat3 axis and that Notch pathway in astrocytes may serve as a promising therapeutic target for SCI.