MicroRNA-135a inhibits cardiac fibrosis induced by isoproterenol via TRPM7 channel

Isoproterenol mechanisms in inducing myocardial fibrosis and its application as an experimental model for the evaluation of therapeutic potential of phytochemicals and pharmaceuticals

Cardiac injury initiates repair mechanisms and results in cardiac remodeling and fibrosis, which appears to be a leading cause of cardiovascular diseases. Cardiac fibrosis is characterized by the accumulation of extracellular matrix proteins, mainly collagen in the cardiac interstitium. Many experimental studies have demonstrated that fibrotic injury in the heart is reversible; therefore, it is vital to understand different molecular mechanisms that are involved in the initiation, progression, and resolution of cardiac fibrosis to enable the development of antifibrotic agents. Of the many experimental models, one of the recent models that has gained renewed interest is isoproterenol (ISP)-induced cardiac fibrosis. ISP is a synthetic catecholamine, sympathomimetic, and nonselective β-adrenergic receptor agonist. The overstimulated and sustained activation of β-adrenergic receptors has been reported to induce biochemical and physiological alterations and ultimately result in cardiac remodeling. ISP has been used for decades to induce acute myocardial infarction. However, the use of low doses and chronic administration of ISP have been shown to induce cardiac fibrosis; this practice has increased in recent years. Intraperitoneal or subcutaneous ISP has been widely used in preclinical studies to induce cardiac remodeling manifested by fibrosis and hypertrophy. The induced oxidative stress with subsequent perturbations in cellular signaling cascades through triggering the release of free radicals is considered the initiating mechanism of myocardial fibrosis. ISP is consistently used to induce fibrosis in laboratory animals and in cardiomyocytes isolated from animals. In recent years, numerous phytochemicals and synthetic molecules have been evaluated in ISP-induced cardiac fibrosis. The present review exclusively provides a comprehensive summary of the pathological biochemical, histological, and molecular mechanisms of ISP in inducing cardiac fibrosis and hypertrophy. It also summarizes the application of this experimental model in the therapeutic evaluation of natural as well as synthetic compounds to demonstrate their potential in mitigating myocardial fibrosis and hypertrophy.

Exploring the therapeutic mechanisms of heart failure with Chinese herbal medicine: a focus on miRNA-mediated regulation

Heart failure (HF) is a clinical condition caused by abnormalities in the heart's structure or function, primarily manifested as diminished ability of the heart to pump blood, which leads to compensatory activation of neurohormones and increased left ventricular filling pressure. HF is one of the fastest-growing cardiovascular diseases globally in terms of incidence and mortality, negatively impacting patients' quality of life and imposing significant medical and economic burdens. Despite advancements in the treatment of HF, hospitalization and mortality remain rates high. In China, Chinese herbal medicine (CHM) has historically played a prominent role in addressing HF, with significant proven efficacy. MicroRNA (miRNA) exerts a pivotal regulatory influence on the maintenance of regular cardiac activity and the progression of HF. MiRNAs, a category of single-stranded RNA molecules, are characterized by their inability to code for proteins. They regulate gene expression by binding to the 3'-untranslated region (3'-UTR) of target mRNAs, thereby influencing the onset and progression of various diseases. Abnormal expression of specific miRNAs is closely associated with HF pathological processes, such as cardiomyocyte apoptosis, myocardial fibrosis, and cardiac hypertrophy. This abnormal expression can influence the pathological progression of HF through the regulation of miRNA expression. This article reviews the regulatory role of miRNAs in HF pathology discusses how CHM compounds and their active ingredients can ameliorate HF pathology through the regulation of miRNA expression. In conclusion, miRNAs represent promising therapeutic targets for HF, and CHM provides a novel strategy for treatment through the regulation of miRNA expression. Future studies must delve deeper into the precise mechanisms by which CHM modulates miRNAs and fully explore its potential for clinical application in HF treatment.

Targeting TRPM channels for cerebral ischemia-reperfusion injury

Transient receptor potential melastatin (TRPM) channels have emerged as potential therapeutic targets for cerebral ischemia-reperfusion (I/R) injury. We highlight recent findings on the involvement of TRPM channels in oxidative stress, mitochondrial dysfunction, inflammation, and calcium overload. We also discuss the challenges and future directions in targeting TRPM channels for cerebral I/R injury.

miR135a administration ameliorates brain ischemic damage by preventing TRPM7 activation during brain ischemia

BACKGROUND

miRNA-based strategies have recently emerged as a promising therapeutic approach in several neurodegenerative diseases. Unregulated cation influx is implicated in several cellular mechanisms underlying neural cell death during ischemia. The brain constitutively active isoform of transient receptor potential melastatin 7 (TRPM7) represents a glutamate excitotoxicity-independent pathway that significantly contributes to the pathological Ca2+ overload during ischemia.

AIMS

In the light of these premises, inhibition of TRPM7 may be a reasonable strategy to reduce ischemic injury. Since TRPM7 is a putative target of miRNA135a, the aim of the present paper was to evaluate the role played by miRNA135a in cerebral ischemia. Therefore, the specific objectives of the present paper were: (1) to evaluate miR135a expression in temporoparietal cortex of ischemic rats; (2) to investigate the effect of the intracerebroventricular (icv) infusion of miR135a on ischemic damage and neurological functions; and (3) to verify whether miR135a effects may be mediated by an alteration of TRPM7 expression.

METHODS

miR135a expression was evaluated by RT- PCR and FISH assay in temporoparietal cortex of ischemic rats. Ischemic volume and neurological functions were determined in rats subjected to transient middle cerebral artery occlusion (tMCAo) after miR135a intracerebroventricular perfusion. Target analysis was performed by Western blot.

RESULTS

Our results demonstrated that, in brain cortex, 72 h after ischemia, miR135a expression increased, while TRPM7 expression was parallelly downregulated. Interestingly, miR135a icv perfusion strongly ameliorated the ischemic damage and improved neurological functions, and downregulated TRPM7 protein levels.

CONCLUSIONS

The early prevention of TRPM7 activation is protective during brain ischemia.

Non-coding RNAs modulate pyroptosis in myocardial ischemia-reperfusion injury: A comprehensive review

Reperfusion therapy is the most effective treatment for acute myocardial infarction. However, reperfusion itself can also cause cardiomyocytes damage. Pyroptosis has been shown to be an important mode of myocardial cell death during ischemia-reperfusion. Non-coding RNAs (ncRNAs) play critical roles in regulating pyroptosis. The regulation of pyroptosis by microRNAs, long ncRNAs, and circular RNAs may represent a new mechanism of myocardial ischemia-reperfusion injury. This review summarizes the currently known regulatory roles of ncRNAs in myocardial ischemia-reperfusion injury and interactions between ncRNAs. Potential therapeutic strategies using ncRNA modulation are also discussed.

Magnesium reabsorption in the kidney

Mg²⁺ is essential for many cellular and physiological processes, including muscle contraction, neuronal activity, and metabolism. Consequently, the blood Mg²⁺ concentration is tightly regulated by balanced intestinal Mg²⁺ absorption, renal Mg²⁺ excretion, and Mg²⁺ storage in bone and soft tissues. In recent years, the development of novel transgenic animal models and identification of Mendelian disorders has advanced our current insight in the molecular mechanisms of Mg²⁺ reabsorption in the kidney. In the proximal tubule, Mg²⁺ reabsorption is dependent on paracellular permeability by claudin-2/12. In the thick ascending limb of Henle's loop, the claudin-16/19 complex provides a cation-selective pore for paracellular Mg²⁺ reabsorption. The paracellular Mg²⁺ reabsorption in this segment is regulated by the Ca²⁺-sensing receptor, parathyroid hormone, and mechanistic target of rapamycin (mTOR) signaling. In the distal convoluted tubule, the fine tuning of Mg²⁺ reabsorption takes place by transcellular Mg²⁺ reabsorption via transient receptor potential melastatin-like types 6 and 7 (TRPM6/TRPM7) divalent cation channels. Activity of TRPM6/TRPM7 is dependent on hormonal regulation, metabolic activity, and interacting proteins. Basolateral Mg²⁺ extrusion is still poorly understood but is probably dependent on the Na⁺ gradient. Cyclin M2 and SLC41A3 are the main candidates to act as Na⁺/Mg²⁺ exchangers. Consequently, disturbances of basolateral Na⁺/K⁺ transport indirectly result in impaired renal Mg²⁺ reabsorption in the distal convoluted tubule. Altogether, this review aims to provide an overview of the molecular mechanisms of Mg²⁺ reabsorption in the kidney, specifically focusing on transgenic mouse models and human hereditary diseases.

miR-135a Regulates Atrial Fibrillation by Targeting Smad3

Background

Atrial fibrillation (AF) is the most common arrhythmia in clinical. Atrial fibrosis is a hallmark feature of atrial structural remodeling in AF, which is regulated by the TGF-β1/Smad3 pathway. Recent studies have implicated that miRNAs are involved in the process of AF. However, the regulatory mechanisms of miRNAs remain largely unknown. This study is aimed at investigating the function and regulatory network of miR-135a in AF.

Methods

In vivo, the plasma was collected from patients with AF and non-AF subjects. Adult SD rats were induced by acetylcholine (ACh) (66 μg/ml)-CaCl₂ (10 mg/ml) to establish an AF rat model. In vitro, atrial fibroblasts (AFs), isolated from adult SD rats, were treated with high-frequency electrical stimulation (HES) (12 h) and hypoxia (24 h) to mimic the AF and atrial fibrosis, respectively. miR-135a expression was detected through quantitative real-time polymerase chain reaction (qRT-PCR). The association between miR-135a and Smad3 was speculated by the TargetScan database and confirmed by the luciferase reporter assay. Fibrosis-related genes, Smad3, and TRPM7 were all assessed.

Results

The expression of miR-135a was markedly decreased in the plasma of AF patients and AF rats, which was consistent with that in HES-treated and hypoxia-treated AFs. Smad3 was identified as a target of miR-135a. the downregulation of miR-135a was associated with the enhancement of Smad3/TRPM7 expressions in AFs. Additionally, the knockdown of Smad3 significantly reduced the expression of TRPM7 and further inhibited atrial fibrosis.

Conclusions

Our study demonstrates that miR-135a regulates AF via Smad3/TRPM7, which is a potential therapeutic target for AF.

Emerging role of transient receptor potential (TRP) ion channels in cardiac fibroblast pathophysiology

Cardiac fibroblasts make up a major proportion of non-excitable cells in the heart and contribute to the cardiac structural integrity and maintenance of the extracellular matrix. During myocardial injury, fibroblasts can be activated to trans-differentiate into myofibroblasts, which secrete extracellular matrix components as part of healing, but may also induce cardiac fibrosis and pathological cardiac structural and electrical remodeling. The mechanisms regulating such cellular processes still require clarification, but the identification of transient receptor potential (TRP) channels in cardiac fibroblasts could provide further insights into the fibroblast-related pathophysiology. TRP proteins belong to a diverse superfamily, with subgroups such as the canonical (TRPC), vanilloid (TRPV), melastatin (TRPM), ankyrin (TRPA), polycystin (TRPP), and mucolipin (TRPML). Several TRP proteins form non-selective channels that are permeable to cations like Na+ and Ca2+ and are activated by various chemical and physical stimuli. This review highlights the role of TRP channels in cardiac fibroblasts and the possible underlying signaling mechanisms. Changes in the expression or activity of TRPs such as TRPCs, TRPVs, TRPMs, and TRPA channels modulate cardiac fibroblasts and myofibroblasts, especially under pathological conditions. Such TRPs contribute to cardiac fibroblast proliferation and differentiation as well as to disease conditions such as cardiac fibrosis, atrial fibrillation, and fibroblast metal toxicity. Thus, TRP channels in fibroblasts represent potential drug targets in cardiac disease.

Expression of cardiovascular-related microRNAs is altered in L-arginine:glycine amidinotransferase deficient mice

In humans and mice, L-arginine:glycine amidinotransferase (AGAT) and its metabolites homoarginine (hArg) and creatine have been linked to cardiovascular disease (CVD), specifically myocardial infarction (MI) and heart failure (HF). The underlying molecular and regulatory mechanisms, however, remain unclear. To identify potential pathways of cardiac AGAT metabolism, we sequenced microRNA (miRNA) in left ventricles of wild-type (wt) compared to AGAT-deficient (AGAT^-/-) mice. Using literature search and validation by qPCR, we identified eight significantly regulated miRNAs in AGAT^-/- mice linked to atherosclerosis, MI and HF: miR-30b, miR-31, miR-130a, miR-135a, miR-148a, miR-204, miR-298, and let-7i. Analysis of Gene Expression Omnibus (GEO) data confirmed deregulation of these miRNAs in mouse models of MI and HF. Quantification of miRNA expression by qPCR in AGAT^-/- mice supplemented with creatine or hArg revealed that miR-30b, miR-31, miR-130a, miR-148a, and miR-204 were regulated by creatine, while miR-135a and miR-298 showed a trend of regulation by hArg. Finally, bioinformatics-based target prediction showed that numerous AGAT-dependent genes previously linked to CVD are likely to be regulated by the identified miRNAs. Taken together, AGAT deficiency and hArg/creatine supplementation are associated with cardiac miRNA expression which may influence cardiac (dys)function and CVD.

microRNA-135a-5p regulates NOD-like receptor family pyrin domain containing 3 inflammasome-mediated hypertensive cardiac inflammation and fibrosis via thioredoxin-interacting protein

Hypertension is a severe public health problem that induces cardiac injury with alterations of gene expressions. The current study sought to evaluate the mechanism of microRNA(miR)-135a-5p in NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-mediation of cardiac inflammation and hypertensive cardiac fibrosis. Firstly, hypertensive mouse models were established using angiotensin II (Ang II), followed by miR-135a-5p agomir treatment. Subsequently, mouse blood pressure and basic cardiac function indexes, histopathological changes, and cardiac fibrosis were all determined, in addition to detection of factors related to inflammation and fibrosis. Additionally, mice cardiac fibroblasts (CFs) were isolated and treated with Ang II. The binding relationship of miR-135a-5p and thioredoxin-interacting protein (TXNIP) was predicted and testified, while the interaction of TXNIP and NLRP3 was detected by means of a co-immunoprecipitation assay. It was found that miR-135a-5p was poorly-expressed in Ang II-treated mice and further exerted cardioprotective effects against hypertensive heart diseases. Moreover, over-expression of miR-135a-5p resulted in inhibition of inflammatory infiltration and almost eliminated cardiac fibrosis, as evidenced by decreased Collagen (COL)-I, COL-III, a-smooth muscle actin, NLRP3, tumor necrosis factor-α, and interleukin-6. Mechanically, miR-135a-5p inhibited TXNIP expression to block the binding of TXNIP and NLRP3. On the other hand, TXNIP up-regulation reversed the protective role of miR-135a-5p over-expression in CFs. Collectively, our findings indicated that miR-135a-5p over-expression inhibited TXNIP expression to block the binding of TXNIP and NLRP3, thereby alleviating hypertensive cardiac inflammation and fibrosis.

miR-30a-5p inhibits the proliferation and collagen formation of cardiac fibroblasts in diabetic cardiomyopathy

Cardiac fibrosis is one of the major pathological characteristics of diabetic cardiomyopathy (DCM). MicroRNAs (miRNAs, miRs) have been identified as key regulators in the progression of cardiac fibrosis. This study aimed to investigate the role of miR-30a-5p in DCM and the underlying mechanism. The rat model of diabetes mellitus (DM) was established by streptozotocin injection, and the rat primary cardiac fibroblasts (CFs) were isolated from cardiac tissue and then treated with high glucose (HG). MTT assay was performed to assess the viability of CFs. Dual-luciferase reporter gene assay was conducted to verify the interaction between miR-30a-5p and Smad2. The expression of miR-30a-5p was downregulated in the myocardial tissues of DM rats and HG-stimulated CFs. Overexpression of miR-30a-5p reduced Smad2 levels and inhibited collagen formation in HG-stimulated CFs and DM rats, as well as decreased the proliferation of CFs induced by HG. Smad2 was a target of miR-30a-5p and its expression was inhibited by miR-30a-5p. Furthermore, the simultaneous overexpression of Smad2 and miR-30a-5p reversed the effect of miR-30a-5p overexpression alone in CFs. Our results indicated that miR-30a-5p reduced Smad2 expression and also induced a decrease in proliferation and collagen formation in DCM.

Regional Diversities in Fibrogenesis Weighed as a Key Determinant for Atrial Arrhythmogenesis

Atrial fibrosis plays a key role in atrial myopathy, resulting in the genesis of atrial fibrillation (AF). The abnormal distribution of fibrotic tissue, electrical coupling, paracrine interactions, and biomechanical–electrical interactions have all been suggested as causes of fibrosis-related arrhythmogenesis. Moreover, the regional difference in fibrogenesis, specifically the left atrium (LA) exhibiting a higher arrhythmogenesis and level of fibrosis than the right atrium (RA) in AF, is a key contributor to atrial arrhythmogenesis. LA fibroblasts have greater profibrotic cellular activities than RA fibroblasts, but knowledge about the regional diversity of atrial regional fibrogenesis remains limited. This article provides a comprehensive review of research findings on the association between fibrogenesis and arrhythmogenesis from laboratory to clinical evidence and updates the current understanding of the potential mechanism underlying the difference in fibrogenesis between the LA and RA.

MicroRNA-451a attenuates angiotensin II-induced cardiac fibrosis and inflammation by directly targeting T-box1

Hypertension or angiotensin II (Ang II) induces cardiac inflammation and fibrosis, thus contributing to cardiac remodeling. MicroRNAs (miRNAs) are considered crucial regulators of cardiac homeostasis and remodeling in response to various types of stress. It has been reported that miR-451a is involved in regulating ischemic heart injury. However, its role in Ang II-induced cardiac fibrosis remains unknown. Cardiac remodeling was induced in mice by infusion of low-dose Ang II (490 ng/kg/min) with a minipump for 2 weeks. Echocardiography and histological examinations were performed to evaluate cardiac function and pathological changes. We observed that miR-451a expression was the most significantly downregulated in the hearts of Ang II-infused mice and in both primary cardiac myocytes and fibroblasts. Overexpression of miR-451a in mice significantly attenuated Ang II-induced cardiac fibrosis and inflammation. Conversely, knockdown of miR-451a in mice aggravated this effect. Bioinformatics analysis and a luciferase reporter assay revealed that TBX1 was a direct target of miR-451a. Mechanistically, miR-451a directly targeted TBX1 expression, which inhibited TGF-β1 production in both cardiac myocytes and fibroblasts, inactivating of TGF-β1/SMAD2/3 signaling, inhibiting myofibroblast differentiation and proinflammatory cytokine expression, and leading to attenuation of cardiac fibrosis and inflammation. In conclusion, these results indicate that miR-451a acts as a novel regulator of Ang II-induced cardiac fibrosis and inflammation by directly targeting TBX1, and may be a promising therapeutic target for treating hypertensive cardiac diseases.

Identification of ceRNA (lncRNA-miRNA-mRNA) Regulatory Network in Myocardial Fibrosis After Acute Myocardial Infarction

Purpose

Materials and Methods

Results

Conclusion

Inhibition of Long Noncoding RNA SNHG20 Improves Angiotensin II-Induced Cardiac Fibrosis and Hypertrophy by Regulating the MicroRNA 335/Galectin-3 Axis

Cardiac fibrosis is a hallmark of various heart diseases and ultimately leads to heart failure. Although long noncoding RNA (lncRNA) SNHG20 has been reported to play important roles in various cancers, its function in cardiac fibrosis remains unclear. The expression of SNHG20 and microRNA 335 (miR-335) in heart tissues of angiotensin II-induced mice and angiotensin II-stimulated mouse cardiomyocyte cell line HL-1 were detected by quantitative real-time PCR (qRT-PCR). Cell viability was evaluated by cell counting kit-8 assay. The expression of galectin-3, fibrosis-related proteins (fibronectin, collagen IaI, and α-SMA), and apoptosis-related proteins [cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase (PARP)] was detected by Western blotting. Bioinformatics prediction, luciferase reporter assay, and RNA pulldown assay were performed to determine the relationship between SNHG20 and miR-335 as well as miR-335 and Galectin-3. Gain- and loss-function assays were performed to determine the role of SNHG20/miR-335/Galectin-3 in cardiac fibrosis. SNHG20 was significantly upregulated and miR-335 was downregulated in heart tissues of angiotensin II-treated mice and angiotensin II-stimulated HL-1 cells. Downregulation of SNHG20 effectively enhanced cell viability and decreased cell size of HL-1 cells and the expression levels of fibrosis-related proteins (fibronectin, collagen IaI, and α-SMA) and apoptosis-related proteins (cleaved caspase-3 and cleaved PARP), which were induced by angiotensin II treatment. Furthermore, SNHG20 elevated the expression levels of Galectin-3 by directly regulating miR-335. Our study revealed that downregulation of SNHG20 improved angiotensin II-induced cardiac fibrosis by targeting the miR-335/Galectin-3 axis, suggesting that SNHG20 is a therapeutic target for cardiac fibrosis and hypertrophy.

MicroRNAs in organ fibrosis: From molecular mechanisms to potential therapeutic targets

Fibrosis is caused by chronic tissue injury and characterized by the excessive deposition of extracellular matrix (ECM) that ultimately results in organ failure and death. Owing to lacking of effective treatment against tissue fibrosis, it causes a high morbidity and mortality worldwide. Thus, it is of great importance to find an effective therapy strategy for the treatment of fibrosis. MicroRNAs (miRNAs) play vital roles in many biological processes by targeting downstream genes. Numerous studies demonstrated that miRNAs served as biomarkers of various diseases, suggesting the potential therapeutic targets for diseases. It was recently reported that miRNAs played an important role in the development of organ fibrosis, which showed a promising prospect against fibrosis by targeting intervention. Here, we summarize the roles of miRNAs in the process of organ fibrosis, including liver, lung, heart and kidney, and highlight miRNAs being novel therapeutic targets for organ fibrosis.

MiR-135a Protects against Myocardial Injury by Targeting TLR4

Emerging evidence highlights the importance of microRNAs (miRNAs) as functional regulators in cardiovascular disease. This study aimed to investigate the functional significance of miR-135a in the regulation of cardiac injury after isoprenaline (ISO) stimulation and the underlying mechanisms of its effects. Murine models with cardiac-specific overexpression of miR-135a were constructed with an adeno-associated virus expression system. The cardiac injury model was induced by ISO injection (60 mg/kg per day for 14 d). In vitro, we used H9c2 cells to establish a cell injury model by ISO stimulation (10 µM). The results indicated that miR-135a was increased during days 0-6 of ISO injection and was then downregulated during days 8-14 of ISO injection. The expression of miR-135a was consistent with the in vivo findings. Moreover, mice with cardiac overexpression of miR-135a exhibited reduced cardiac fibrosis, lactate dehydrogenase levels, Troponin I, inflammatory response and apoptosis. Overexpression of miR-135a also ameliorated cardiac dysfunction induced by ISO. MiR-135 overexpression in H9c2 cells increased cell viability and decreased cell apoptosis and inflammation in response to ISO. Conversely, miR-135 silencing in H9c2 cells decreased cell viability and increased cell apoptosis and inflammation in response to ISO. Mechanistically, we found that miR-135a negatively regulated toll-like receptor 4 (TLR4), which was confirmed by luciferase assay. Furthermore, the TLR4 inhibitor eritoran abolished the adverse effect of miR-135 silencing. Overall, miR-135a promotes ISO-induced cardiac injury by inhibiting the TLR4 pathway. MiR-135a may be a therapeutic agent for cardiac injury.

Vincristine attenuates cardiac fibrosis through the inhibition of NLRP3 inflammasome activation

Vincristine (VCR) is widely used in cancer therapies, although its benefits on cardiac fibrosis remain unknown. Here, we investigated VCR's efficacy on cardiac fibrosis and elucidated the underlying mechanism of action. Network pharmacology was employed to predict the mechanism of VCR action on cardiac fibrosis. We induced cardiac fibrosis in adult male Sprague-Dawley (SD) rats via isoproterenol (ISO) injection, followed by treatment with VCR or vehicle. After 10 days of treatment, VCR-treated rats exhibited a significantly lower heart/body weight ratio relative to those treated with the vehicle. Moreover, cardiac fibrosis was alleviated in VCR-treated rats relative to vehicle-treated rats. The results revealed the down-regulation of mature caspase-1, interleukin (IL)-1β, and IL-18 in VCR-treated rats relative to vehicle-treated rats. We also observed less colocalization between the nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) and apoptosis-associated speck-like protein containing a CARD (ASC) in VCR-treated rats compared with vehicle-treated rats. We then cultured neonatal rat cardiac fibroblasts (NRCFs) and exposed them to lipopolysaccharide (LPS) and adenosine triphosphate (ATP) in the presence or absence of VCR. The results indicated that VCR mediated the down-regulation of caspase-1, IL-1β, and IL-18 and the colocalization of NLRP3 and ASC in LPS+ATP-stimulated cardiac fibroblasts (CFs). We found evidence that VCR attenuates cardiac fibrosis by directly suppressing the activation of the NLRP3 inflammasome. These findings provide novel insights into VCR's mechanism of action in alleviating cardiac fibrosis.

A Brief Review on the Biology and Effects of Cellular and Circulating microRNAs on Cardiac Remodeling after Infarction

Despite advances in diagnostic, prognostic, and treatment modalities, myocardial infarction (MI) remains a leading cause of morbidity and mortality. Impaired cellular signaling after an MI causes maladaptive changes resulting in cardiac remodeling. MicroRNAs (miRNAs/miR) along with other molecular components have been investigated for their involvement in cellular signaling in the pathogenesis of various cardiac conditions like MI. miRNAs are small non-coding RNAs that negatively regulate gene expression. They bind to complementary mRNAs and regulate the rate of protein synthesis by altering the stability of their targeted mRNAs. A single miRNA can modulate several cellular signaling pathways by targeting hundreds of mRNAs. This review focuses on the biogenesis and beneficial effects of cellular and circulating (exosomal) miRNAs on cardiac remodeling after an MI. Particularly, miR-1, -133, 135, and -29 that play an essential role in cardiac remodeling after an MI are described in detail. The limitations that will need to be addressed in the future for the further development of miRNA-based therapeutics for cardiovascular conditions will also be discussed.

Channelling the Force to Reprogram the Matrix: Mechanosensitive Ion Channels in Cardiac Fibroblasts

Cardiac fibroblasts (CF) play a pivotal role in preserving myocardial function and integrity of the heart tissue after injury, but also contribute to future susceptibility to heart failure. CF sense changes to the cardiac environment through chemical and mechanical cues that trigger changes in cellular function. In recent years, mechanosensitive ion channels have been implicated as key modulators of a range of CF functions that are important to fibrotic cardiac remodelling, including cell proliferation, myofibroblast differentiation, extracellular matrix turnover and paracrine signalling. To date, seven mechanosensitive ion channels are known to be functional in CF: the cation non-selective channels TRPC6, TRPM7, TRPV1, TRPV4 and Piezo1, and the potassium-selective channels TREK-1 and KATP. This review will outline current knowledge of these mechanosensitive ion channels in CF, discuss evidence of the mechanosensitivity of each channel, and detail the role that each channel plays in cardiac remodelling. By better understanding the role of mechanosensitive ion channels in CF, it is hoped that therapies may be developed for reducing pathological cardiac remodelling.

Role of TRPM7 in cardiac fibrosis: A potential therapeutic target (Review)

Cardiac fibrosis is a hallmark of cardiac remodeling associated with nearly all forms of heart disease. Clinically, no effective therapeutic drugs aim to inhibit cardiac fibrosis, owing to the complex etiological heterogeneity and pathogenesis of this disease. A two-in-one protein structure, a ubiquitous expression profile and unique biophysical characteristics enable the involvement of transient receptor potential melastatin-subfamily member 7 (TRPM7) in the pathogenesis and development of fibrosis-related cardiac diseases, such as heart failure (HF), cardiomyopathies, arrhythmia and hyperaldosteronism. In response to a variety of stimuli, multiple bioactive molecules can activate TRPM7 and related signaling pathways, leading to fibroblast proliferation, differentiation and extracellular matrix production in cardiac fibroblasts. TRPM7-mediated Ca²⁺ signaling and TGF-β1 signaling pathways are critical for the formation of fibrosis. Accumulating evidence has demonstrated that TRPM7 is a potential pharmacological target for halting the development of fibrotic cardiac diseases. Reliable drug-like molecules for further development of high-affinity in vivo drugs targeting TRPM7 are urgently needed. The present review discusses the widespread and significant role of TRPM7 in cardiac fibrosis and focuses on its potential as a therapeutic target for alleviating heart fibrogenesis.

Panax Notoginseng Saponins suppresses TRPM7 via the PI3K/AKT pathway to inhibit hypertrophic scar formation in vitro

BACKGROUND

Hypertrophic scar (HS) formation, a type of dermal fibroproliferative condition, is a frequent complication in wound healing resulting from burns, severe trauma, and surgical procedures. The effects of Panax Notoginseng Saponins (PNS) on the HS formation remain relatively under-explored. Hence, this study was intended to interrogate anti-apoptosis and anti-fibrosis effects of PNS on the hypertrophic scar fibroblasts (HSFs) during HS formation and assess the involvement of TRPM7 and PI3K/AKT signaling pathway.

METHODS

Using MTT and CCK-8 assays, we evaluated cell cytotoxicity and cell viability. Collagen I/III (col 1/3) and α-SMA expression levels were assessed through immunofluorescence and western blot, and cell migration, cell apoptosis and cell cycle were examined with applications of wound healing, TUNEL staining and flow cytometry. TRPM7, PI3K/AKT, TGF-β1 and related-proteins were quantified using RT-qPCR and western blot.

RESULTS

PNS administration could suppress TRPM7 expression and the viability of HSFs in a dose-dependent manner. Moreover, PNS could restrain the HS formation and ECM deposition by decreasing col 1/3 and α-SMA synthesis, suppressing cell migration, and boosting apoptosis and G1 arrest. Notably, this study revealed that PNS inhibited PI3K/AKT activation in HSFs. Besides, knockdown of TRPM7 enhanced therapeutic effects of PNS on HSFs, but overexpression markedly reversed above mentioned effects of PNS on HSFs.

CONCLUSION

This study suggested that PNS hampered scar formation might via inhibiting ECM and stimulating cell apoptosis by modulating the PI3K/AKT signaling. Overall, these findings in the present study could support the use of PNS for preventing HS formation, and TRPM7 may be a novel molecular target for treating HS.

LncRNA SOX2OT/Smad3 feedback loop promotes myocardial fibrosis in heart failure

Long noncoding RNA SOX2OT is associated with myocardial fibrosis (MF) in heart failure (HF). This article aims to investigate the role of SOX2OT in MF. We constructed HF mouse models by subcutaneous injection of isoprenaline (ISO). Cardiac fibroblasts (CFs) were treated with ISO to induce MF.Hematoxylin-eosin, Masson, and Sirius-red staining were used to identify myocardial injury and collagen deposition in heart tissues. The relationship among SOX2OT, miR-138-5p, TGF-β1, and Smad3 were evaluated by chromatin immunoprecipitation and luciferase reporter assay. The gene and protein expression were verified by quantitative real-time PCR and western blot. We found that SOX2OT was up-regulated in HF mice and ISO-induced CFs. SOX2OT knockdown reduced myocardial injury and collagen deposition in HF mice. The expression of collagen I, α-SMA, TGF-β1, and p-Smad3 were inhibited by SOX2OT down-regulation in HF mice and ISO-induced CFs. Furthermore, TGF-β1 was a target gene of miR-138-5p and indirectly regulated by SOX2OT. SOX2OT promoted MF in HF by activating TGF-β1/Smad3, and then Smad3 interacted with the SOX2OT promoter and formed a positive feedback loop. In conclusion, our work verifies that SOX2OT/Smad3 feedback loop promotes MF in HF. Thus, SOX2OT is potentially a novel therapeutic target for MF in HF.

Cardioprotective Effects of Dietary Flaxseed Post-Infarction Are Associated with Changes in MicroRNA Expression

MicroRNAs (miRNAs/miRs) such as miR-1, miR-133a, miR-133b, miR-135a, and miR-29b play a key role in many cardiac pathological remodeling processes, including apoptosis, fibrosis, and arrhythmias, after a myocardial infarction (MI). Dietary flaxseed has demonstrated a protective effect against an MI. The present study was carried out to test the hypothesis that dietary flaxseed supplementation before and after an MI regulates the expression of above-mentioned miRNAs to produce its cardioprotective effect. Animals were randomized after inducing MI by coronary artery ligation into: (a) sham MI with normal chow, (b) MI with normal chow, and (c–e) MI supplemented with either 10% milled flaxseed, or 4.4% flax oil enriched in alpha-linolenic acid (ALA), or 0.44% flax lignan secoisolariciresinol diglucoside. The feeding protocol consisted of 2 weeks before and 8 weeks after the surgery. Dietary flax oil supplementation selectively upregulated the cardiac expression of miR-133a, miR-135a, and miR-29b. The levels of collagen I expression were reduced in the flax oil group. We conclude that miR-133a, miR-135a, and miR-29b are sensitive to dietary flax oil, likely due to its rich ALA content. The cardioprotective effect of flaxseed in an MI could be due to modulation of these miRNAs.

miR-135a Alleviates Silica-Induced Pulmonary Fibrosis by Targeting NF-κB/Inflammatory Signaling Pathway

Silica exposure triggers inflammatory response and pulmonary fibrosis that is a severe occupational or environmental lung disease with no effective therapies. The complicated biological and molecular mechanisms underlying silica-induced lung damages have not yet been fully understood. miR-135a inhibits inflammation, apoptosis, and cancer cell proliferation. But the roles of miRNA135a involved in the silica-induced lung damages remain largely unexplored. We investigated the roles and mechanisms of miR-135a underlying silica-induced pulmonary fibrosis. The present study showed silica exposure caused the decrease in miR-135a level but the increase in inflammatory mediators. Transduction of lentivirus expressing miR-135a reduced the level of inflammatory mediators in lung tissues from silica-treated mice and improved pulmonary fibrosis which was consistent with the downregulated α-SMA but enhanced E-cadherin. Moreover, miR-135a overexpression inhibited p-p65 level in lung tissues. Overexpression of miR-135a inhibitor strengthened TLR4 protein level and NF-κB activation in BEAS-2B cells. Injection of PDTC, an inhibitor of NF-κB, further reinforced miR-135a-mediated amelioration of inflammation and pulmonary fibrosis induced by silica. The collective data indicate miR-135a restrains NF-κB activation probably through targeting TLR4 to alleviate silica-induced inflammatory response and pulmonary fibrosis.

Inhibition of miRNA‑135a‑5p ameliorates TGF‑β1‑induced human renal fibrosis by targeting SIRT1 in diabetic nephropathy

miRNA-135a-5p upregulation has been identified in renal fibrosis in diabetic nephropathy (DN) with an incompletely known mechanism. Previous data showed that Sirtuin 1 (SIRT1) serves as a novel therapeutic target for DN and interact with the transforming growth factor-β/mothers against decapentaplegic homolog (TGF-β/Smad) signaling pathway. The aim of this study was to investigate the regulatory relationship between miR-135a-5p and SIRT1. The expression of miR-135a-5p and SIRT1 was detected using reverse transcription-quantitative PCR and western blotting. The renal fibrosis and Smad3 signaling pathway were assessed by western blotting, by analyzing protein expression of collegen1A1, α-smooth muscle actin (α-SMA), fibronectin (FN), epithelial-cadherin, Smad3 and phosphorylated Smad3 (p-Smad3). The target binding between miR-135a-5p and SIRT1 was predicted on TargetScan Human software, and confirmed by dual-luciferase reporter assay and RNA immu-noprecipitation. The results demonstrated miR-135a-5p is upregulated and SIRT1 was downregulated in the serum and renal tissue of DN patients, and TGFβ1-induced DN cell models in human HK-2 and HMCs. Knockdown of miR-135a-5p and overexpression of SIRT1 could inhibit TGFβ1-induced renal fibrosis in vitro. Moreover, SIRT1 was a downstream target for miR-135a-5p. Silencing of SIRT1 could abolish the suppressive role of miR-135a-5p knockdown in TGFβ1-induced HK-2 and HMCs. The TGFβ1 induced p-Smad3 expression in HK-2 and HMCs, which could be attenuated by miR-135a-5p knockdown via SIRT1. In conclusion, knockdown of miR-135a-5p inhibits TGFβ1-induced renal fibrosis by targeting SIRT1 and inactivating Smad3 signaling, providing a novel insight into miR-135a-5p as a potential therapeutic approach for DN.

Quantitative proteomics characterization of acutely isolated primary adult rat cardiomyocytes and fibroblasts

Our heart is comprised of many different cell types that all contribute to cardiac function. An important step in deciphering the molecular complexity of our heart is to decipher the molecular composition of the various cardiac cell types. Here we set out to delineate a comprehensive protein expression profile of the two most prevalent cell types in the heart: cardiomyocytes and cardiac fibroblasts. To this end, we isolated cardiomyocytes and fibroblasts from rat hearts and combined state-of-the-art flow cytometry with high-resolution mass spectrometry to investigate their proteome profiles right after isolation. We measured and quantified 5240 proteins in cardiomyocytes and 6328 proteins in cardiac fibroblasts. In addition to providing a global protein profile for these cardiac cell types, we also present specific findings, such as unique expression of ion channels and transcription factors for each cell type. For instance, we show that the sodium channel Scn7a and the cation channel Trpm7 are expressed in fibroblasts but not in cardiomyocytes, which underscores the importance of investigating the endogenous cell host prior to functional studies. Our dataset represents a valuable resource on protein expression profiles in these two primary cardiac cells types.

Astragaloside IV inhibits cardiac fibrosis via miR-135a-TRPM7-TGF-β/Smads pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Cardiac fibrosis is a common characteristic of many cardiac diseases. Our previous results showed that TRPM7 channel played an important role in the fibrosis process. MicroRNA-135a was reported to get involved in the fibrotic process. Astragalus membranaceus (Fisch.) Bunge was widely used in Chinese traditional medicine and showed cardiac protective effects in previous researches. Astragaloside IV(ASG), which is regarded as the most important ingredient of Astragalus, has been showed the effect of cardiac protection via various mechanisms, while no data suggested its action related to miRNAs regulation.

AIM OF THE STUDY

The objective of this article is to investigate the inhibition effect of ASG on cardiac fibrosis through the miR-135a-TRPM7-TGF-β/Smads pathway.

MATERIALS AND METHODS

We extracted the active components from herb according to the paper and measured the content of ASG from the mixture via HPLC. The inhibition potency of cardiac hypertrophy between total extract of Astragalus and ASG was compared. SD rats were treated with ISO (5 mg/kg/day) subcutaneously (s.c.) for 14 days, ASG (10 mg/kg/d) and Astragalus extract (AE) (4.35 g/kg/d, which contained about ASG 10 mg) were given p.o. from the 6th day of the modeling. Cardiac fibroblasts (CFs) of neonatal rats were incubated with ISO (10 μM) and treated with ASG (10 μM) simultaneously for 24 h.

RESULTS

The results showed that both AE and ASG treatment reduced the TRPM7 expression from the gene level and inhibited cardiac fibrosis. ASG group showed similar potency as the AE mixture. ASG treatment significantly decreased the current, mRNA and protein expression of TRPM7 which was one of targets of miR-135a. The activation of TGF-β/Smads pathway was suppressed and the expression of α-SMA and Collagen I were also decreased obviously. In addition, our results showed that there was a positive feedback between the activation of TGF-β/Smads pathway and the elevation of TRPM7, both of which could promote the development of myocardial fibrosis.

CONCLUSIONS

AE had the effect of cardiac fibrosis inhibition and decreased the mRNA expression of TRPM7. ASG, as one of the effective ingredients of AE, showed the same potency when given the same dose. ASG inhibited cardiac fibrosis by targeting the miR-135a-TRPM7-TGF-β/Smads pathway.

Angiotensin-II-Evoked Ca2+ Entry in Murine Cardiac Fibroblasts Does Not Depend on TRPC Channels

TRPC proteins form cation conducting channels regulated by different stimuli and are regulators of the cellular calcium homeostasis. TRPC are expressed in cardiac cells including cardiac fibroblasts (CFs) and have been implicated in the development of pathological cardiac remodeling including fibrosis. Using Ca²⁺ imaging and several compound TRPC knockout mouse lines we analyzed the involvement of TRPC proteins for the angiotensin II (AngII)-induced changes in Ca²⁺ homeostasis in CFs isolated from adult mice. Using qPCR we detected transcripts of all Trpc genes in CFs; Trpc1, Trpc3 and Trpc4 being the most abundant ones. We show that the AngII-induced Ca²⁺ entry but also Ca²⁺ release from intracellular stores are critically dependent on the density of CFs in culture and are inversely correlated with the expression of the myofibroblast marker α-smooth muscle actin. Our Ca²⁺ measurements depict that the AngII- and thrombin-induced Ca²⁺ transients, and the AngII-induced Ca²⁺ entry and Ca²⁺ release are not affected in CFs isolated from mice lacking all seven TRPC proteins (TRPC-hepta KO) compared to control cells. However, pre-incubation with GSK7975A (10 µM), which sufficiently inhibits CRAC channels in other cells, abolished AngII-induced Ca²⁺ entry. Consequently, we conclude the dispensability of the TRPC channels for the acute neurohumoral Ca²⁺ signaling evoked by AngII in isolated CFs and suggest the contribution of members of the Orai channel family as molecular constituents responsible for this pathophysiologically important Ca²⁺ entry pathway.

miR-26b inhibits isoproterenol-induced cardiac fibrosis via the Keap1/Nrf2 signaling pathway

A critical event in cardiac fibrosis is the transformation of cardiac fibroblasts (CFs) into myofibroblasts. MicroRNAs (miRNAs) have been reported to be critical regulators in the development of cardiac fibrosis. However, the underlying molecular mechanisms of action of miRNA (miR)-26b in cardiac fibrosis have not yet been extensively studied. In the present study, the expression levels of miR-26b were downregulated in isoproterenol (ISO)-treated cardiac tissues and CFs. Moreover, miR-26b overexpression inhibited the cell viability of ISO-treated CFs and decreased the protein levels of collagen I and α-smooth muscle actin (α-SMA). Furthermore, bioinformatics analysis and dual luciferase reporter assays indicated that Kelch-like ECH-associated protein 1 (Keap1) was the target of miR-26b, and that its expression levels were decreased in miR-26b-treated cells. In addition, Keap1 overexpression reversed the inhibitory effects of miR-26b on ISO-induced cardiac fibrosis, as demonstrated by cell viability, and the upregulation of collagen I and α-SMA expression levels. Furthermore, inhibition of Keap1 expression led to the activation of nuclear factor erythroid 2-related factor 2 (Nrf2), which induced the transcriptional activation of antioxidant/detoxifying proteins in order to protect against cardiac fibrosis. Taken together, the data demonstrated that miR-26b attenuated ISO-induced cardiac fibrosis via the Keap-mediated activation of Nrf2.

CDR1as/miRNAs-related regulatory mechanisms in muscle development and diseases

Muscles are critical tissues for mammals due to their close association with movement and physiology. Myogenesis involves proliferation, differentiation, and fusion of myoblast, in which many well-known protein-coding genes, as well as linear non-coding RNAs such as microRNAs (miRNAs), are involved. Recently, circular RNAs (circRNAs) have attracted much attention since several circRNAs are known to play significant roles in muscle development and diseases through limited mechanisms, particularly through sponging miRNAs. Through advanced researches, increasing evidence suggests that Cerebellar Degeneration-Related protein 1 antisense (CDR1as) is an important circRNA that regulates the levels of mRNAs expression via competitively sponged miRNAs. Here, we reviewed the robust expression and base pairing relationships of CDR1as and several myogenic miRNAs, as well as these miRNAs and their targeted genes in muscles or some muscle-related diseases. These potential CDR1as/miRNAs/mRNA pathways will provide the basis for further research on the function of CDR1as in muscle development, and eventually extend the versatile roles of CDR1as in mammals.

let-7a suppresses liver fibrosis via TGFβ/SMAD signaling transduction pathway

Liver fibrosis is the most common pathological outcome and the most severe complication of chronic liver diseases. Accumulating evidence suggests that miRNAs are involved in cell proliferation, differentiation, apoptosis, as well as the occurrence and development of various diseases. In this study, we found that the expression of let-7a was markedly decreased in the liver tissue samples and blood samples from patients with liver fibrosis compared with healthy volunteers. Furthermore, let-7a was downregulated in the liver tissues and blood samples in mouse models of liver fibrosis. Further analysis indicated that let-7a suppresses the activation level of hepatic stellate cells (HSCs). In addition, overexpression of let-7a reduced cell viability and promoted apoptosis of HSCs. Western blot analysis showed that let-7a might inhibit HSCs through TGFβ/SMAD signaling pathway. The present study provides a potential accurate target and vital evidence to better understand the underlying pathogenesis for early diagnosis and treatment of liver fibrosis.

miR-543 inhibites cervical cancer growth and metastasis by targeting TRPM7

Dysregulation of miR-543 has been implicated to play crucial roles in various human cancers. However, the function of miR-543 involved in cervical cancer (CC) progress remains largely unknown. Thus, this study aimed to explore the potential role of miR-543 and the underlying mechanisms in human CC. In this study, we found that miR-543 was significantly downregulated in 69 CC tissue samples and cell lines when compared to adjacent normal tissues and cell line. Decreased miR-543 was closely correlated with poor clinicopathological parameters including larger tumor size, late FIGO stage and lymph node metastasis. Overexpression of miR-543 in CC cell lines remarkably inhibited cell proliferation, invasion and migration, caused cell cycle arrest, promoted apoptosis in vitro, and suppressed tumor growth in vivo, whereas miR-543 inhibitor showed the opposite effect. Dual-luciferase assay validated that 3'-untranslated region (UTR) of transient receptor potential melastatin 7 (TRPM7) was a direct binding site of miR-543. Rescue experiments showed that restoration of TRPM7 expression partially reversed the miR-543-mediated inhibition of proliferation and invasion in CC cells. Further studies confirmed that P13K/AKT and p38/MAPK signaling was involved in miR-543/TRPM7 axis mediated CC progression. Thus, these findings demonstrated the tumor suppressor role of miR-543 on CC progression, which might serve as a potential biomarker for CC diagnosis and therapy.

TRP Channels: Current Perspectives in the Adverse Cardiac Remodeling

Calcium is an important second messenger required not only for the excitation-contraction coupling of the heart but also critical for the activation of cell signaling pathways involved in the adverse cardiac remodeling and consequently for the heart failure. Sustained neurohumoral activation, pressure-overload, or myocardial injury can cause pathologic hypertrophic growth of the heart followed by interstitial fibrosis. The consequent heart’s structural and molecular adaptation might elevate the risk of developing heart failure and malignant arrhythmia. Compelling evidences have demonstrated that Ca²⁺ entry through TRP channels might play pivotal roles in cardiac function and pathology. TRP proteins are classified into six subfamilies: TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPA (ankyrin), TRPML (mucolipin), and TRPP (polycystin), which are activated by numerous physical and/or chemical stimuli. TRP channels participate to the handling of the intracellular Ca²⁺ concentration in cardiac myocytes and are mediators of different cardiovascular alterations. This review provides an overview of the current knowledge of TRP proteins implication in the pathologic process of some frequent cardiac diseases associated with the adverse cardiac remodeling such as cardiac hypertrophy, fibrosis, and conduction alteration.

microRNA-135a protects against myocardial ischemia-reperfusion injury in rats by targeting protein tyrosine phosphatase 1B

microRNAs are an emerging class of molecules that regulate pathogenesis of cardiovascular diseases. Here we aim to elucidate the effects and mechanism of miR-135a, a previously reported regulator of ischemia-reperfusion (I/R) injury, in myocardial I/R injury. Quantitative real-time polymerase chain reaction analysis revealed that the expression level of miR-135a was significantly decreased both in the rat I/R group and H9c2 cells subjected to hypoxia/reoxygenation. Overexpression of miR-135a in vivo markedly decreased the infarct size and inhibited the I/R-induced cardiomyocyte apoptosis. Overexpression of miR-135a in H9c2 also exerted antiapoptosis effects. Furthermore, bioinformatics analysis, luciferase activity, and the Western blot assay indicated that protein tyrosine phosphatase 1B (PTP1B) is a direct target of miR-135a. In addition, the expression of proapoptotic-related genes, such as p53, Bax, and cleaved caspase3, were decreased in association with the downregulation of PTP1B. In summary, this study demonstrates that miR-135a exerts protective effects against myocardial I/R injury by targeting PTP1B.