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Aims: Cardiac lipotoxicity is the common consequence of lipid metabolism disorders in cardiomyocytes during development of heart failure (HF). Adenosine 5′monophosphate-activated protein kinase (AMPK) acts as an energy sensor and has a beneficial effect in reducing lipotoxicity. Notoginsenoside R1 (NGR1) is extracted from the traditional Chinese medicine Panax notoginseng (Burkill) F.H.Chen (P. notoginseng) and has definite cardioprotective effects. However, whether NGR1 can attenuate HF by mitigating lipotoxicity has not been elucidated yet. This study aimed to explore whether NGR1 plays a protective role against HF by ameliorating cardiac lipotoxicity via the AMPK pathway.Methods: In this study, HF mice model was established by left anterior descending (LAD) ligation. palmitic acid (PA) stimulated H9C2 cell model was applied to clarify the effects and potential mechanism of NGR1 on lipotoxicity. In vivo, NGR1 (7.14 mg/kg/days) and positive drug (simvastatin: 2.9 mg/kg/days) were orally administered for 14 days. Echocardiography was applied to assess heart functions. Lipid levels were measured by Enzyme-linked immunosorbent assay (ELISA) and key proteins in the AMPK pathway were detected by western blots. In vitro, NGR1 (40 μmol/L) or Compound C (an inhibitor of AMPK, 10 μmol/L) was co-cultured with PA stimulation for 24 h in H9C2 cells. CCK-8 assay was used to detect cell viability. Key lipotoxicity-related proteins were detected by western blots and the LipidTOX™ neutral lipid stains were used to assess lipid accumulation. In addition, Apoptosis was assessed by Hoechst/PI staining.Results: NGR1 could significantly improve the cardiac function and myocardial injury in mice with HF and up-regulate the expression of p-AMPK. Impressively, NGR1 inhibited the synthesis of diacylglycerol (DAG) and ceramide and promoted fatty acid oxidation (FAO) in vivo. Moreover, NGR1 significantly promoted expression of CPT-1A, the key enzyme in FAO pathway, and down-regulated the expression of GPAT and SPT, which were the key enzymes catalyzing production of DAG and ceramide. In vitro experiments showed that NGR1 could significantly attenuate lipid accumulation in PA-induced H9C2 cells and the Hoechst/PI staining results showed that NGR1 ameliorated lipotoxicity-induced apoptosis in PA-stimulated H9C2 cell model. Furthermore, co-treatment with inhibitor of AMPK abrogated the protective effects of NGR1. The regulative effects of NGR1 on lipid metabolism were also reversed by AMPK inhibitor.Conclusion: NGR1 could significantly improve the heart function of mice with HF and reduce cardiac lipotoxicity. The cardio-protective effects of NGR1 are mediated by the activation of AMPK pathway.

Doxorubicin (DOX) is one of the most effective chemotherapeutic agents. However, its clinical use is limited due to the severe risk of cardiotoxicity. One of the hallmarks of doxorubicin-induced cardiotoxicity (DICT) is the cascade of mitophagy deficiency-mitochondrial oxidative injury-apoptosis, while so far, there is no preventive strategy for alleviating DICT by targeting this molecular mechanism. Excitedly, based on our previous drug screen in DICT zebrafish model, harpagoside (HAR) showed dramatic anti-DICT efficacy superior to dexrazoxane (DXZ) only cardioprotectant approved by FDA. Therefore, its pharmacological effects and molecular mechanism on DICT mouse and rat cardiomyocytes were further discussed. In vivo, HAR significantly improved cardiac function and myocardial structural lesions with concomitant of diminished mitochondrial oxidative damage and recovered mitophagy flux. In parallel, HAR protected mitophagy and mitochondria homeostasis, and repressed apoptosis in vitro. Intriguingly, both nutlin-3 (agonist of p53) and Parkin siRNA reversed these protective effects of HAR. Additional data, including fluorescence colocalization of Parkin and MitoTracker and mt-Keima for the detection of mitophagy flux and coimmunoprecipitation of p53 and Parkin, showed that HAR promoted Parkin translocation to mitochondria and substantially restored Parkin-mediated mitophagy by inhibiting the binding of p53 and Parkin. Importantly, the results of the cell viability demonstrated that cardioprotective effect of HAR did not interfere with anticancer effect of DOX on MCF-7 and HepG2 cells. Our research documented p53-Parkin-mediated cascade of mitophagy deficiency-mitochondrial dyshomeostasis-apoptosis as a pathogenic mechanism and druggable pathway and HAR as a cardioprotection on DICT by acting on novel interaction between p53 and Parkin.

Aim: Inflammation and fibrosis have been shown to be critical factors in heart failure (HF) progression. Calycosin (Cal) is the major active component of Astragalus mongholicus Bunge and has been reported to have therapeutic effects on the cardiac dysfunction after myocardial infarction. However, whether Cal could ameliorate myocardial infarction (MI)-induced inflammation and fibrosis and precise mechanisms remain uncertain. The aim of this study is to explore the role of Cal in HF and to clarify the underlying mechanisms.Methods: For in vivo experiments, rats underwent left anterior descending artery ligation for heart failure model, and the cardioprotective effects of Cal were measured by echocardiographic assessment and histological examination. RNA-seq approach was applied to explore potential differential genes and pathways. For further mechanistic study, proinflammatory-conditioned media (conditioned media)-induced H9C2 cell injury model and TGFβ-stimulated cardiac fibroblast model were applied to determine the regulatory mechanisms of Cal.Results: In the in vivo experiments, echocardiography results showed that Cal significantly improved heart function. GO and reactome enrichment revealed that inflammation and fibrosis pathways are involved in the Cal-treated group. KEGG enrichment indicated that the PI3K–AKT pathway is enriched in the Cal-treated group. Further experiments proved that Cal alleviated cardiomyocyte inflammatory responses evidenced by downregulating the expressions of phosphorylated IκB kinase α/β (p-IKKα/β), phosphorylated nuclear factor kapa B (p-NFκB), and tumor necrosis factor α (TNFα). Besides, Cal effectively attenuated cardiac fibrosis through the inhibitions of expressions and depositions of collagen I and collagen III. In the in vitro experiments, the phosphatidylinositol three kinase (PI3K) inhibitor LY294002 could abrogate the anti-inflammation and antifibrosis therapeutic effects of Cal, demonstrating that the cardioprotective effects of Cal were mediated through upregulations of PI3K and serine/threonine kinase (AKT).Conclusion: Cal inhibited inflammation and fibrosis via activation of the PI3K–AKT pathway in H9C2 cells, fibroblasts, and heart failure in postacute myocardial infarction rats.

Background: Doxorubicin (DOX), a broad-spectrum chemotherapy drug, has life-threatening cardiotoxicity. Therefore, searching cardioprotective drugs for DOX-induced cardiotoxicity (DIC) is urgently needed.Objectives: This study aimed to explore cardioprotective effect and specific mechanism by which Ferruginol (FGL) attenuated DIC in vivo and in vitro.Methods: We evaluated the cardioprotection of FGL and performed high-throughput RNA-Seq on a DIC mouse. Whereafter, multiple methods, including western blot, RT-qPCR, a transmission electron microscope, CO-IP, immunofluorescence, and other staining methods, and antagonist of SIRT1 and PGC-1α were utilized to confirm the cardioprotection and molecular mechanism of FGL.Results: FGL-exerted cardioprotection manifested as enhanced cardiac function and reduced structural damage and apoptosis. The transcriptome and other results revealed that FGL facilitated PGC-1α-mediated mitochondrial biogenesis and fatty acid oxidation (MB and FAO) by increasing the expression of PGC-1α and concurrently promoting the expression of SIRT1-enhancing deacetylase SIRT1 deacetylating and activating PGC-1α.Conclusions: These results documented that FGL exerted cardioprotective effects restoring MB&FAO via the SIRT1–PGC-1α axis.