This study investigated the mechanism by which NR4A1 regulates mitochondrial fission factor (Mff)-related mitochondrial fission and FUN14 domain 1 (FUNDC1)-mediated mitophagy following cardiac ischemia-reperfusion injury(I/R). Our findings showed that the damage regulation was positively correlated with the pathological fission and pan-apoptosis of myocardial cell mitochondria. Compared with wild-type mice (WT), NR4A1-knockout mice exhibited resistance to myocardial ischemia-reperfusion injury and mitochondrial pathological fission, characterized by mitophagy activation. Results showed that ischemia-reperfusion injury increased NR4A1 expression level, activating mitochondrial fission mediated by Mff and restoring the mitophagy phenotype mediated by FUNDC1. The inactivation of FUNDC1 phosphorylation could not mediate the normalization of mitophagy in a timely manner, leading to an excessive stress response of unfolded mitochondrial proteins and an imbalance in mitochondrial homeostasis. This process disrupted the normalization of the mitochondrial quality control network, leading to accumulation of damaged mitochondria and the activation of pan-apoptotic programs. Our data indicate that NR4A1 is a novel and critical target in myocardial I/R injury that exertsand negative regulatory effects by activating Mff-mediated mito-fission and inhibiting FUNDC1-mediated mitophagy. Targeting the crosstalk balance between NR4A1-Mff-FUNDC1 is a potential approach for treating I/R.

Heart failure (HF) leads to an increase in morbidity and mortality globally. Tanshinone IIA is an important traditional Chinese medicine monomer and has been shown to have remarkable protective effect against HF. Autophagy is critically involved in the progression of HF. The effect of Tanshinone IIA on autophagy has not been clarified yet. In this study, left anterior descending (LAD) ligation was used to induce HF model and a hydrogen peroxide-(H₂O₂-)-induced H9C2 cell injury model was established. in vivo, echocardiography results showed that Tanshinone IIA could significantly improve heart function. Western Blot result showed that Tanshinone IIA treatment enhanced autophagy and regulated expressions of key autophagy-related molecules, including protein 1 light chain 3 (LC3), p62 and Beclin1. Tanshinone IIA also inhibited apoptosis and regulated expressions of key apoptotic protein, including B cell lymphoma-2 (Bcl-2) and Bcl-2 Associated X Protein (Bax) and cleaved caspase-3 and -7. Further experiments demonstrated that the effects of Tanshinone IIA were mediated through upregulation of AMP-activated protein kinase (AMPK) and downregulation of mammalian target of rapamycin (mTOR) simultaneously. The mTOR agonist MHY1485 could abrogate the therapeutic effect of Tanshinone IIA in vitro. In conclusion, Tanshinone IIA protects cardiomyocytes and improves cardiac function by inhibiting apoptosis and inducing autophagy via activation of the AMPK-mTOR signaling pathway.

Septic cardiomyopathy (SCM) is a complication of myocardial injury in patients with severe sepsis. This study highlights the potential of Astragaloside IV(AS) in the treatment of septic cardiomyopathy and provides a reference for developing cardioprotective drugs targeting DUSP1-PHB2-related mitochondria-ER interaction. Dual specificity phosphatase-1 (DUSP1)/Prohibitin 2 cardiomyocyte-specific knockout mice (DUSP1/PHB2^CKO) /DUSP1 transgenic mice (DUSP1/PHB2^TG) were used to generate LPS-induced sepsis models. The pathological mechanism by which AS-IV improves heart injury was detected using cardiac ultrasound, fluorescence staining, transmission electron microscopy, and western blotting. After siRNA treatment of cardiomyocytes with DUSP-1/PHB2, changes in mitochondrial function and morphology were determined using qPCR, western blotting, ELISA, and laser confocal microscopy, and the targeted therapeutic effects of AS-IV were further examined. SCM treatment leads to severe mitochondrial dysfunction. However, Astragaloside IV (AS) treatment normalizes mitochondrial homeostasis and ER function. Notably, the protective effect was blocked in DUSP1/Prohibitin 2 cardiomyocyte-specific knockout mice (DUSP1/PHB2^CKO) but remained unaffected in DUSP1 transgenic mice (DUSP1/PHB2^TG). This study highlights the potential of AS in the treatment of septic cardiomyopathy and provides a reference for developing cardioprotective drugs targeting DUSP1-PHB2 related mitochondria-ER interaction.

Cardiac fibrosis is a common pathological progress of cardiovascular disease resulting from the excessive accumulation of extracellular matrix (ECM). Transforming growth factor (TGF)-β/SMADs pathway is a canonical signaling pathway which directly induces expressions of ECM related genes. Qishen Granule (QSG), a traditional Chinese formula developed from Zhen-Wu Decoration for heart failure (HF), has been proven to have definite therapeutic effects on cardiac fibrosis. However, its underlying mechanisms remain unclear. To investigate the effects of QSG on TGF-β pathway and the downstream mediators including Smad3 and Glycogen synthase kinase (GSK)-3β. HF model was induced by ligation of left coronary artery on male Sprague-Dawley (SD) rats. Rat were randomly divided into four groups including sham group, model group, QSG group and Fosinopril control group. Rats in each group were treated for 28 days, and 2D echocardiography was adopted to evaluate the heart function. The degree of cardiac fibrosis was assessed by Hematoxylin-Eosin (HE), Masson's trichrome and Picrosirius red (PSR) staining. Contents of collagen Ⅰ and Ⅲ were assessed by immunohistochemical method. Expressions of genes and proteins in TGF-β/SMADs and PI3K-GSK-3 signaling pathways were detected by Real-time Fluorescence Quantitative PCR (RT-qPCR) and Western blot respectively. TGF-β1-treated cardiac fibroblasts of neonatal SD rats were adopted for in vitro studies. 28 days after the surgery, cardiac ejection fraction (EF) and fractional shortening (FS) values in the model group showed a remarkable decrease, indicating the induction of HF model. QSG and Fosinopril elevated the EF and FS values, demonstrating cardio-protective effects. Pathological staining and immunohistochemistry showed that the contents of collagen I and III dramatically increased in the cardiac tissue of the model group compared with the sham group while QSG treatment reduced collagen contents. Furthermore, expressions of TGF-β1, p-Smad3 and p-GSK-3β were significantly decreased in the QSG treatment group compared with the model group, suggesting that the QSG may attenuate cardiac fibrosis through regulating TGF-β/Smad3 pathway. In vitro study further showed that the productions of type Ⅰ and Ⅲ collagen and α-smooth muscle actin (α-SMA) of cardiac fibroblasts were significantly increased by incubation with TGF-β1. QSG could markedly reduce the secretion of collagen Ⅰ and Ⅲ and α-SMA expression. Protein expressions of p-Smad3, PI3K, p-Akt and p-GSK-3β were significantly up-regulated by stimulation of TGF-β1. Treatment with QSG could suppress the activity of Smad3 and PI3K-GSK-3β signaling pathway in cardiac fibroblasts. QSG improves cardiac function through inhibiting cardiac fibrosis. The anti-fibrotic effects are potentially mediated by the inhibition of the TGF-β/Smad3 pathway and the phosphorylation of GSK-3β.

Background: Doxorubicin is effective in a variety of solid and hematological malignancies. Unfortunately, clinical application of doxorubicin is limited due to a cumulative dose-dependent cardiotoxicity. Dihydrotanshinone I (DHT) is a natural product from Salvia miltiorrhiza Bunge with multiple anti-tumor activity and anti-inflammation effects. However, its anti-doxorubicin-induced cardiotoxicity (DIC) effect, either in vivo or in vitro, has not been elucidated yet. This study aims to explore the anti-inflammation effects of DHT against DIC, and to elucidate the potential regulatory mechanism. Methods: Effects of DHT on DIC were assessed in zebrafish, C57BL/6 mice and H9C2 cardiomyocytes. Echocardiography, histological examination, flow cytometry, immunochemistry and immunofluorescence were utilized to evaluate cardio-protective effects and anti-inflammation effects. mTOR agonist and lentivirus vector carrying GFP-TFEB were applied to explore the regulatory signaling pathway. Results: DHT improved cardiac function via inhibiting the activation of M1 macrophages and the excessive release of pro-inflammatory cytokines both in vivo and in vitro. The activation and nuclear localization of NF-κB were suppressed by DHT, and the effect was abolished by mTOR agonist with concomitant reduced expression of nuclear TFEB. Furthermore, reduced expression of nuclear TFEB is accompanied by up-regulated phosphorylation of IKKα/β and NF-κB, while TFEB overexpression reversed these changes. Intriguingly, DHT could upregulate nuclear expression of TFEB and reduce expressions of p-IKKα/β and p-NF-κB. Conclusions: Our results demonstrated that DHT can be applied as a novel cardioprotective compound in the anti-inflammation management of DIC via mTOR-TFEB-NF-κB signaling pathway. The current study implicates TFEB-IKK-NF-κB signaling axis as a previously undescribed, druggable pathway for DIC.

Heart failure (HF) leads to an increase in morbidity and mortality globally. Disorders of energy metabolism and apoptosis of cardiomyocytes are critically involved in the progression of HF. Ginsenoside Rb3 (G-Rb3) is a natural product derived from ginseng that has cardio-protective effect. The pharmacological mechanism of G-Rb3 in the treatment of HF remains to be clarified. In this study, we aimed to explore the regulative effects of G-Rb3 on fatty acids oxidation and apoptosis by in vivo and in vitro studies. Myocardial infarction (MI)-induced HF mice model and a cellular H9C2 injury model was induced by oxygen-glucose deprivation/reperfusion (OGD/R) stimulation. The results showed that G-Rb3 could protect heart functions in MI-induced HF model. G-Rb3 treatment up-regulated expressions of key enzymes involved in β-oxidation of fatty acids, including carnitine palmitoyltransterase-1α (CPT-1α), acyl-CoA dehydrogenase long chain (ACADL) and the major mitochondrial deacetylase enzyme sirtuin 3 (SIRT3). The upstream transcriptional regulator, peroxisome proliferator-activated receptor α (PPARα), was also up-regulated by G-Rb3 treatment. In vitro study demonstrated that G-Rb3 could protect mitochondrial membrane integrity and exert anti-apoptotic effects, in addition to regulating fatty acids oxidation. Impressively, after cells were co-treated with PPARα inhibitor, the regulative effects of G-Rb3 on energy metabolism and apoptosis were abrogated. Our study suggests that G-Rb3 is a promising agent and PPARα is potential target in the management of HF.