Maduramicin-activated protein phosphatase 2A results in extracellular signal-regulated kinase 1/2 inhibition, leading to cytotoxicity in myocardial H9c2 cells

Network Pharmacology Combined with Bioinformatics to Investigate the Mechanisms and Molecular Targets of Astragalus Radix-Panax notoginseng Herb Pair on Treating Diabetic Nephropathy

Background

Astragalus Radix (AR)-Panax notoginseng (PN), a classical herb pair, has shown significant effects in treating diabetic nephropathy (DN). However, the intrinsic mechanism of AR-PN treating DN is still unclear. This study aims to illustrate the mechanism and molecular targets of AR-PN treating DN based on network pharmacology combined with bioinformatics.

Materials and Methods

The Traditional Chinese Medicine Systems Pharmacology database was used to screen bioactive ingredients of AR-PN. Subsequently, putative targets of bioactive ingredients were predicted utilizing the DrugBank database and converted into genes on UniProtKB database. DN-related targets were retrieved via analyzing published microarray data (GSE30528) from the Gene Expression Omnibus database. Protein-protein interaction networks of AR-PN putative targets and DN-related targets were established to identify candidate targets using Cytoscape 3.8.0. GO and KEGG enrichment analyses of candidate targets were reflected using a plugin ClueGO of Cytoscape. Molecular docking was performed using AutoDock Vina software, and the results were visualized by Pymol software. The diagnostic capacity of hub genes was verified by receiver operating characteristic (ROC) curves.

Results

Twenty-two bioactive ingredients and 189 putative targets of AR-PN were obtained. Eight hundred and fifty differently expressed genes related to DN were screened. The PPI network showed that 115 candidate targets of AR-PN against DN were identified. GO and KEGG analyses revealed that candidate targets of AR-PN against DN were mainly involved in the apoptosis, oxidative stress, cell cycle, and inflammation response, regulating the PI3K-Akt signaling pathway, cell cycle, and MAPK signaling pathway. Moreover, MAPK1, AKT1, GSK3B, CDKN1A, TP53, RELA, MYC, GRB2, JUN, and EGFR were considered as the core potential therapeutic targets. Molecular docking demonstrated that these core targets had a great binding affinity with quercetin, kaempferol, isorhamnetin, and formononetin components. ROC curve analysis showed that AKT1, TP53, RELA, JUN, CDKN1A, and EGFR are effective in discriminating DN from controls.

Conclusions

AR-PN against DN may exert its renoprotective effects via various bioactive chemicals and the related pharmacological pathways, involving multiple molecular targets, which may be a promising herb pair treating DN. Nevertheless, these results should be further validated by experimental evidence.

Maduramicin induces cardiotoxicity via Rac1 signaling-independent methuosis in H9c2 cells

Maduramicin frequently induces severe cardiotoxicity in target and nontarget animals in clinic. Apoptotic and non-apoptotic cell death mediate its cardiotoxicity; however, the underlying non-apoptotic cell death induced by maduramicin remains unclear. In current study, a recently described non-apoptotic cell death "methuosis" caused by maduramicin was defined in mammalian cells. Rat myocardial cell H9c2 was used as an in vitro model, showing excessively cytoplasmic vacuolization upon maduramicin (0.0625-5 μg/mL) exposure for 24 h. Maduramicin-induced reversible cytoplasmic vacuolization of H9c2 cells in a time- and concentration-dependent manner. The vacuoles induced by maduramicin were phase lucent with single membrane and were not derived from the swelling of organelles such as mitochondria, endoplasmic reticulum, lysosome, and Golgi apparatus. Furthermore, maduramicin-induced cytoplasmic vacuoles are generated from micropinocytosis, which was demonstrated by internalization of extracellular fluid-phase marker Dextran-Alexa Fluor 488 into H9c2 cells. Intriguingly, these cytoplasmic vacuoles acquired some characteristics of late endosomes and lysosomes rather than early endosomes and autophagosomes. Vacuolar H⁺ -ATPase inhibitor bafilomycin A1 efficiently prevented the generation of cytoplasmic vacuoles and decreased the cytotoxicity of H9c2 cells triggered by maduramicin. Mechanism studying indicated that maduramicin activated H-Ras-Rac1 signaling pathway at both mRNA and protein levels. However, the pharmacological inhibition and siRNA knockdown of Rac1 rescued maduramicin-induced cytotoxicity of H9c2 cells but did not alleviate cytoplasmic vacuolization. Based on these findings, maduramicin induces methuosis in H9c2 cells via Rac-1 signaling-independent seriously cytoplasmic vacuolization.

Maduramicin triggers methuosis-like cell death in primary chicken myocardial cells

Maduramicin frequently induces severe cardiotoxicity in broiler chickens as well as in humans who consume maduramicin accidentally. Apoptosis and non-apoptotic cell death occur concurrently in the process of maduramicin-induced cardiotoxicity; however, the underlying mechanism of non-apoptotic cell death is largely unknown. Here, we report the relationship between maduramicin-caused cytoplasmic vacuolization and methuosis-like cell death as well as the underlying mechanism in primary chicken myocardial cells. Maduramicin induced a significant increase of cytoplasmic vacuoles with a degree of cell specificity in primary chicken embryo fibroblasts and chicken hepatoma cells (LMH), along with a decrease of ATP and an increase of LDH. The accumulated vacuoles were partly derived from cellular endocytosis rather than the swelling of endoplasm reticulum, lysosomes, and mitochondria. Moreover, the broad-spectrum caspase inhibitor carbobenzoxy-Val-Ala-Asp-fluoromethylketone (z-VAD-fmk) did not prevent maduramicin-induced cytoplasmic vacuolization. DNA ladder and cleavage of PARP were not observed in chicken myocardial cells during maduramicin exposure. Pretreatment with 3-methyladenine (3-MA) and cholorquine (CQ) of chicken myocardial cells did not attenuate cytoplasmic vacuolization and cytotoxicity, although LC3 and p62 were activated. Bafilomycin A1 almost completely prevented the generation of cytoplasmic vacuoles and significantly attenuated cytotoxicity induced by maduramicin, along with downregulation of K-Ras and upregulation of Rac1. Taken together, "methuosis" due to excessive cytoplasmic vacuolization mediates the cardiotoxicity of maduramicin. This provides new insights for understanding a nonclassical form of cell death in the field of drug-induced cytotoxicity.

Network Pharmacology-Based Dissection of the Anti-diabetic Mechanism of Lobelia chinensis

Diabetes mellitus (DM) is a chronic inflammatory disease, and the rapidly increasing DM is becoming a major problem of global public health. Traditional Chinese medicine (TCM) has a long history of treating diabetes. It has been developed and utilized because of its good efficacy and no toxic side effects. Lobelia chinensis is a traditional whole grass herbal. With the continuous deepening of pharmacological research on TCM, the active ingredients of L. chinensis are continuously revealed, which contained the alkaloids, flavonoids, flavonoid glycosides and amino acids that have the good effects of anti-inflammatory, anti-viral and anti-diabetic. In order to further explore the targets of active ingredients and its anti-diabetic mechanism, a feasible network pharmacology analysis model based on chemical, pharmacokinetic and pharmacological data was developed by network construction method to clarify the anti-diabetic mechanism of L. chinensis. The present study conducted by gas chromatography–mass spectrometer (GC/MS), which identified 208 metabolites of L. chinensis, of which 23 ingredients may have effective pharmacological effects after absorption, distribution, metabolism, and excretion (ADME) screening. Network pharmacological analysis on the active ingredients revealed that 5-hydroxymethylfurfural in L. chinensis affects the insulin resistance signaling pathway by acting on GSK3B, TNF, and MAPK1, acacetin affects the diabetic pathway by acting on INSR, DPP4, and GSK3B, that regulate type 2 diabetes, non-insulin-dependent DM, and inflammatory diseases. These results successfully indicated the potential anti-diabetic mechanism of the active ingredients of L. chinensis.

Maduramicin induces apoptosis through ROS-PP5-JNK pathway in skeletal myoblast cells and muscle tissue

Our previous work has shown that maduramicin, an effective coccidiostat used in the poultry production, executed its toxicity by inducing apoptosis of skeletal myoblasts. However, the underlying mechanism is not well understood. Here we show that maduramicin induced apoptosis of skeletal muscle cells by activating c-Jun N-terminal kinase (JNK) pathway in murine C2C12 and L6 myoblasts as well as skeletal muscle tissue. This is supported by the findings that inhibition of JNK with SP600125 or ectopic expression of dominant negative c-Jun attenuated maduramicin-induced apoptosis in C2C12 cells. Furthermore, we found that treatment with maduramicin reduced the cellular protein level of protein phosphatase 5 (PP5). Overexpression of PP5 substantially mitigated maduramicin-activated JNK and apoptosis. Moreover, we noticed that treatment with maduramicin elevated intracellular reactive oxygen species (ROS) level. Pretreatment with N-acetyl-L-cysteine (NAC), a ROS scavenger and antioxidant, suppressed maduramicin-induced inhibition of PP5 and activation of JNK as well as apoptosis. The results indicate that maduramicin induction of ROS inhibits PP5, which results in activation of JNK cascade, leading to apoptosis of skeletal muscle cells. Our finding suggests that manipulation of ROS-PP5-JNK pathway may be a potential approach to prevent maduramicin-induced apoptotic cell death in skeletal muscle.

Long circulatory liposomal maduramicin inhibits the growth of Plasmodium falciparum blood stages in culture and cures murine models of experimental malaria

Malaria continues to be one of the deadliest infectious diseases and a global health menace. The emergence and spread of drug-resistant strains of malaria parasites have further made the process of disease management grimmer. Thus, there is an urgent need to identify promising antimalarial strategies that can target the blood stages as well as block parasite transmission. Maduramicin is one such ionophore selected out of a recent screen of gametocytocidal compounds that exhibit potent antiplasmodial activity. However, maduramicin's strong hydrophobic nature and associated toxicity restrict its application in chemotherapy. To alleviate this problem, we have developed a liposomal formulation loaded with the ionophore maduramicin for the treatment of chloroquine sensitive and resistant Plasmodium infections. Here, we show that maduramicin in PEGylated liposomal formulations displayed enhanced antiplasmodial activity in vitro compared to free maduramicin. Significantly, four consecutive doses of 1.5 mg kg-1 body weight of PEGylated maduramicin loaded lipid vesicles completely cured cerebral and chloroquine resistant murine models of malaria without any obvious toxic effects and suppressed the key inflammatory markers associated with the progression of the disease. PEGylated liposomal maduramicin also exhibited a prolonged plasma clearance rate, implying a greater chance of interaction and uptake by infected RBCs. Furthermore, we also provide evidence that the detrimental effect of liposomal maduramicin on parasite survival is mediated by increased ROS generation and subsequent perturbation of parasite mitochondrial membrane potential. This study presents the first report to demonstrate the potent antimalarial efficacy of maduramicin liposomes, a strategy that holds promise for the development of successful therapeutic intervention against malaria in humans.