Tetramethylpyrazine attenuates lipopolysaccharide-induced cardiomyocyte injury via improving mitochondrial function mediated by 14-3-3γ

Bibliometric analysis of research progress on tetramethylpyrazine and its effects on ischemia-reperfusion injury

In recent decades, natural products have attracted worldwide attention and become one of the most important resources for pharmacological industries and medical sciences to identify novel drug candidates for disease treatment. Tetramethylpyrazine (TMP) is an alkaloid extracted from Ligusticum chuanxiong Hort., which has shown great therapeutic potential in cardiovascular and cerebrovascular diseases, liver and renal injury, as well as cancer. In this review, we analyzed 1270 papers published on the Web of Science Core Collection from 2002 to 2022 and found that TMP exerted significant protective effects on ischemia-reperfusion (I/R) injury that is the cause of pathological damages in a variety of conditions, such as ischemic stroke, myocardial infarction, acute kidney injury, and liver transplantation. TMP is limited in clinical applications to some extent due to its rapid metabolism, a short biological half-life and poor bioavailability. Obviously, the structural modification, administration methods and dosage forms of TMP need to be further investigated in order to improve its bioavailability. This review summarizes the clinical applications of TMP, elucidates its potential mechanisms in protecting I/R injury, provides strategies to improve bioavailability, which presents a comprehensive understanding of the important compound. Hopefully, the information and knowledge from this review can help researchers and physicians to better improve the applications of TMP in the clinic.

Terpinen-4-ol Improves Lipopolysaccharide-Induced Macrophage Inflammation by Regulating Glutamine Metabolism

Terpinen-4-ol (T-4-O) is an important component of tea tree oil and has anti-inflammatory effects. Currently, there are very few studies on the mechanisms by which T-4-O improves lipopolysaccharide (LPS)-induced macrophage inflammation. In this study, LPS-stimulated mouse RAW264.7 macrophages were used as a model to analyze the effects of T-4-O on macrophage inflammatory factors and related metabolic pathways in an inflammatory environment. The results showed that T-4-O significantly decreased the expression levels of inflammatory cytokines induced by LPS. Cellular metabolism results showed that T-4-O significantly decreased the ratio of the extracellular acidification rate and oxygen consumption rate. Non-targeted metabolomics results showed that T-4-O mainly affected glutamine and glutamate metabolism and glycine, serine, and threonine metabolic pathways. qPCR results showed that T-4-O increased the transcript levels of GLS and GDH and promoted glutamine catabolism. Western blotting results showed that T-4-O inhibited the mTOR and IκB, thereby decreasing NF-κB activity. The overall results showed that T-4-O inhibited mTOR phosphorylation to promote glutamine metabolism and increased cell oxidative phosphorylation levels, thereby inhibiting the expression of LPS-induced inflammatory cytokines.

Research status of pathogenesis of anxiety or depression after percutaneous coronary intervention and Traditional Chinese Medicine intervention

ETHNIC PHARMACOLOGICAL RELEVANCE

Anxiety or depression after percutaneous coronary intervention (PCI) is a common clinical disease. Currently, conventional pharmacotherapy primarily involves the administration of anxiolytic or antidepressant medications in conjunction with anticoagulants, antiplatelet agents, and other cardiovascular drugs. However, challenges such as drug dependence, adverse reactions and related concerns persist in the treatment of this disease. Numerous pertinent studies have demonstrated that Traditional Chinese Medicine (TCM) exhibits significant therapeutic efficacy and distinctive advantages in managing post-PCI anxiety or depression.

AIM OF THIS REVIEW

This review attempted to summarize the characteristics of TCM for treating anxiety or depression after PCI, including single Chinese herbs, Chinese medicine monomers, compound TCM prescriptions, TCM patented drugs, and other TCM-related treatment methods, focusing on the analysis of the relevant mechanism of TCM treatment of this disease.

METHODS

By searching the literature on treating anxiety or depression after PCI with TCM in PubMed, Web of Science, CNKI, and other relevant databases, this review focuses on the latest research progress of TCM treatment of this disease.

RESULTS

In the treatment of anxiety or depression after PCI, TCM exerts significant pharmacological effects such as anti-inflammatory, antioxidant, anti-anxiety or anti-depression, cardiovascular and cerebrovascular protection, and neuroprotection, mainly by regulating the levels of related inflammatory factors, oxidative stress markers, neurotransmitter levels, and related signaling pathways. TCM has a good clinical effect in treating anxiety or depression after PCI with individualized treatment.

CONCLUSIONS

TCM has terrific potential and good prospects in the treatment of anxiety or depression after PCI. The main direction of future exploration is the study of the mechanism related to Chinese medicine monomers and the large sample clinical study related to compound TCM prescriptions.

Interferon-regulatory factor-1 boosts bevacizumab cardiotoxicity by the vascular endothelial growth factor A/14-3-3γ axis

AIM

Myocardial injury is a significant cause of death. This study investigated the role and underlying mechanism of interferon-regulatory factor-1 (IRF1) in bevacizumab (BVZ)-induced cardiomyocyte injury.

METHODS AND RESULTS

HL-1 cells and C57BL/6 mice receiving BVZ treatment were used to establish in vitro and in vivo models of myocardial injury. The relationship between VEGFA and 14-3-3γ was verified through co-immunoprecipitation and Glutathione S Transferase (GST) pull-down assay. Cell viability and apoptosis were analysed by MTT, propidium iodide (PI) staining and flow cytometry. The release of lactate dehydrogenase (LDH), cardiac troponins T (cTnT), and creatine kinase MB (CK-MB) was measured using the enzyme linked immunosorbent assay. The effects of knocking down IRF1 on BVZ-induced mice were analysed in vivo. IRF1 levels were increased in BVZ-treated HL-1 cells. BVZ treatment induced apoptosis, inhibited cell viability, and promoted the release of LDH, cTnT, and CK-MB. IRF1 silencing suppressed BVZ-induced myocardial injury, whereas IRF1 overexpression had the opposite effect. IRF1 regulated VEGFA expression by binding to its promoter, with the depletion of VEGFA or 14-3-3γ reversing the effects of IRF1 knockdown on the cell viability and apoptosis of BVZ-treated HL-1 cells. 14-3-3γ overexpression promoted cell proliferation, inhibited apoptosis, and reduced the release of LDH, cTnT, and CK-MB, thereby alleviating BVZ-induced HL-1 cell damage. In vivo, IRF1 silencing alleviated BVZ-induced cardiomyocyte injury by regulating the VEGFA/14-3-3γ axis.

CONCLUSION

The IRF1-mediated VEGFA/14-3-3γ signalling pathway promotes BVZ-induced myocardial injury. Our study provides evidence for potentially new target genes for the treatment of myocardial injury.

The role of 14-3-3 in the progression of vascular inflammation induced by lipopolysaccharide

OBJECTIVE

To explore the role of 14-3-3 protein and the Hippo and yes-associated protein 1 (YAP) signaling pathway in lipopolysaccharide (LPS)-induced vascular inflammation.

METHODS

Human umbilical vein endothelial cells (HUVECs) and C57B6 mice were treated with LPS to establish cell and animal models of vascular inflammation. Lentiviral transfection, Western blot, qPCR, immunofluorescence, immunohistochemistry, co-immunoprecipitation, and enzyme-linked immunosorbent assays were used to measure inflammatory factors and expression of 14-3-3 protein and phosphorylation of YAP at S127. HUVECs and C57B6 mice were pretreated with a YAP inhibitor, Verteporfin, to observe changes in YAP expression and downstream vascular inflammation.

RESULTS

LPS induced acute and chronic inflammatory responses in HUVECs and mice and upregulated the expression of several inflammatory factors. LPS also induced expression of 14-3-3 protein and phosphorylation of YAP at S127 in response to acute vascular inflammation and downregulated these markers in response to chronic vascular inflammation. Verteporfin reduced these LPS-induced effects on vascular inflammation.

CONCLUSION

In chronic vascular inflammation, 14-3-3 protein is downregulated, which promotes inflammation by increasing Hippo/YAP nuclear translocation.

Puerarin activates adaptive autophagy and protects the myocardium against doxorubicin-induced cardiotoxicity via the 14–3-3γ/PKCε pathway

Doxorubicin (Dox)-induced cardiotoxicity (DIC) seriously threatens the health of related patients. Studies have confirmed that 14-3-3γ and protein kinase C epsilon (PKCε) are the endogenous protective proteins. Puerarin (Pue) is a bioactive ingredient isolated from the root of Pueraria lobata. It possesses many pharmacological properties, which have been widely used in treating and adjuvant therapy of cardiovascular diseases. In the study, we intended to explore the effects and mechanism of Pue pretreatment to protect the myocardium against DIC injury. Adult mice and H9c2 cells were pretreated with Pue, and the injury model was made with Dox. Results showed that Pue pretreatment alleviated DIC injury, as revealed by increased cell viability, decreased LDH activity and apoptosis, inhibited excess oxidative stress, maintained mitochondrial function and energy metabolism, and improved myocardial function. Furthermore, Pue pretreatment upregulated 14-3-3γ expression, interacted with PKCε, phosphorylated and impelled migration to mitochondria, activated adaptive autophagy, and protected the myocardium. However, pAD/14-3-3γ-shRNA or εV1-2 (a PKCε activity inhibitor) or 3-methyladenine (an autophagy inhibitor) could weaken the above effects of Pue pretreatment. Together, Pue pretreatment could activate adaptive autophagy by the 14-3-3γ/PKCε pathway and protect the myocardium against DIC injury.

Tetramethylpyrazine: A review on its mechanisms and functions

Ligusticum chuanxiong Hort (known as Chuanxiong in China, CX) is one of the most widely used and long-standing medicinal herbs in China. Tetramethylpyrazine (TMP) is an alkaloid and one of the active components of CX. Over the past few decades, TMP has been proven to possess several pharmacological properties. It has been used to treat a variety of diseases with excellent therapeutic effects. Here, the pharmacological characteristics and molecular mechanism of TMP in recent years are reviewed, with an emphasis on the signal-regulation mechanism of TMP. This review shows that TMP has many physiological functions, including anti-oxidant, anti-inflammatory, and anti-apoptosis properties; autophagy regulation; vasodilation; angiogenesis regulation; mitochondrial damage suppression; endothelial protection; reduction of proliferation and migration of vascular smooth muscle cells; and neuroprotection. At present, TMP is used in treating cardiovascular, nervous, and digestive system conditions, cancer, and other conditions and has achieved good curative effects. The therapeutic mechanism of TMP involves multiple targets, multiple pathways, and bidirectional regulation. TMP is, thus, a promising drug with great research potential.

Energy metabolism disorders and potential therapeutic drugs in heart failure

Heart failure (HF) is a global public health problem with high morbidity and mortality. A large number of studies have shown that HF is caused by severe energy metabolism disorders, which result in an insufficient heart energy supply. This deficiency causes cardiac pump dysfunction and systemic energy metabolism failure, which determine the development of HF and recovery of heart. Current HF therapy acts by reducing heart rate and cardiac preload and afterload, treating the HF symptomatically or delaying development of the disease. Drugs aimed at cardiac energy metabolism have not yet been developed. In this review, we outline the main characteristics of cardiac energy metabolism in healthy hearts, changes in metabolism during HF, and related pathways and targets of energy metabolism. Finally, we discuss drugs that improve cardiac function via energy metabolism to provide new research ideas for the development and application of drugs for treating HF.

Capsaicin protects cardiomyocytes against lipopolysaccharide-induced damage via 14-3-3γ-mediated autophagy augmentation

Background: The myocardium is susceptible to lipopolysaccharide (LPS)-induced damage in sepsis, and cardiac dysfunction is a leading cause of mortality in patients with sepsis. The changes in cardiomyocyte autophagy in sepsis and the effects and mechanism of action of capsaicin (Cap) remain unclear.

Methods and Results: The potential pathway of 14-3-3γ-dependent autophagy and the effects and mechanisms of Cap were studied in LPS-induced injury to primary cultured neonatal rat cardiomyocytes. The results showed that cardiomyocyte viability decreased, lactate dehydrogenase and creatine kinase activities increased, 14-3-3γ expression was downregulated, and autophagy was inhibited after LPS challenge. Cap pretreatment augmented autophagy by upregulating 14-3-3γ expression and activating AMP-activated protein kinase (AMPK) and unc-51 like autophagy-activating kinase 1 (ULK1), suppressing mammalian target of rapamycin (mTOR), alleviating cardiac dysfunction and improving the inflammation response, whereas pAD/14-3-3γ-shRNA nullified the above effects. Cap pretreatment also decreased the levels of IL-1β, TNF-α, IL-6, and IL-10; suppressed intracellular oxidative stress; reduced the intracellular/mitochondrial reactive oxygen species (ROS); balanced GSH/GSSG; increased GSH-Px, catalase, and SOD activities; and decreased MDA contents. It also increased ATP content, activated complex Ⅰ and complex Ⅲ, stabilized the mitochondrial membrane potential, and decreased the mitochondrial permeability transition pore opening, thereby improving mitochondrial function.

Conclusion: Pretreatment with Cap can regulate autophagy by upregulating 14-3-3γ expression, inhibiting oxidative stress and inflammation, maintaining mitochondrial function, and protecting cardiomyocytes against LPS-induced injury.

Vinegar/Tetramethylpyrazine Induces Nutritional Preconditioning Protecting the Myocardium Mediated by VDAC1

Vinegar is good for health. Tetramethylpyrazine (TMP) is the main component of its flavor, quality, and function. We hypothesized that vinegar/TMP pretreatment could induce myocardial protection of "nutritional preconditioning (NPC)" by low-dose, long-term supplementation and alleviate the myocardial injury caused by anoxia/reoxygenation (A/R). To test this hypothesis, TMP content in vinegar was detected by HPLC; A/R injury model was prepared by an isolated mouse heart and rat cardiomyocyte to evaluate the myocardial protection and mechanism of vinegar/TMP pretreatment by many enzymatic or functional, or cellular and molecular biological indexes. Our results showed that vinegar contained TMP, and its content was in direct proportion to storage time. Vinegar/TMP pretreatment could improve hemodynamic parameters, decrease lactate dehydrogenase (LDH) and creatine phosphokinase activities, and reduce infarct size and apoptosis in the isolated hearts of mice with A/R injury. Similarly, vinegar/TMP pretreatment could increase cell viability, decrease LDH activity, and decrease apoptosis against A/R injury of cardiomyocytes. Vinegar/TMP pretreatment could also maintain the mitochondrial function of A/R-injured cardiomyocytes, including improving oxygen consumption rate and extracellular acidification rate, reducing reactive oxygen species generation, mitochondrial membrane potential loss, mitochondrial permeability transition pore openness, and cytochrome c releasing. However, the protective effects of vinegar/TMP pretreatment were accompanied by the downregulation of VDAC1 expression in the myocardium and reversed by pAD/VDAC1, an adenovirus that upregulates VDAC1 expression. In conclusion, this study is the first to demonstrate that vinegar/TMP pretreatment could induce myocardial protection of NPC due to downregulating VDAC1 expression, inhibiting oxidative stress, and preventing mitochondrial dysfunction; that is, VDAC1 is their target, and the mitochondria are their target organelles. TMP is one of the most important myocardial protective substances in vinegar.

Mechanisms dissection of the combination GRS derived from ShengMai preparations for the treatment of myocardial ischemia/reperfusion injury

ETHNOPHARMACOLOGICAL RELEVANCE

Recently, a new drug combination GRS comprising ginsenoside Rb1 (G-Rb1), ruscogenin (R-Rus) and schisandrin (S-SA) was screened based on ShengMai preparations, which exhibited a prominent cardioprotective effects against myocardial ischemia/reperfusion (MI/R) injury.

AIM OF THE STUDY

To investigate their systemic and individual mechanism of each compound in combination GRS.

MATERIALS AND METHODS

The mice model of MI/R and hypoxia/reoxygenation (H/R)-induced cardiomyocytes injury were performed to explore the respective characteristics of each compound in GRS against myocardial injury.

RESULTS

Each component in the combination GRS attenuated MI/R injury as evidenced by decreased myocardial infarct size, ameliorated histological features, and improved biochemical indicators. Meanwhile, ingredient G, R and S in combination also individually performed a significant decrease of apoptotic index in MI/R mice and H/R-induced cardiomyocytes injury. Mechanistically, component G in GRS could markedly increase the ATP content in cardiomyocytes through activation of AMPKα phosphorylation. Interestingly, the anti-apoptotic actions of G were profoundly attenuated by knockdown of AMPKα, while no alteration was observed on composition R and S. Moreover, component R in GRS significantly reduced the IL-6 and TNF-α mRNA expression, as well as the content of IL-6 via the modulation of NF-κB signaling pathway. Further, component S exhibited the most powerful anti-oxidative capacity in GRS and remarkably decreased the production of MDA and ROS, and potential mechanisms might at least in part through activating the Akt-14-3-3 signaling pathway and inhibiting the phosphorylation of Bad and ERK1/2.

CONCLUSIONS

Our results indicated that the respective mechanism of each compound in combination GRS against MI/R injury might closely associated with energy metabolism modulation, suppression of inflammation and oxidative stress.

Propofol ameliorates endotoxin‑induced myocardial cell injury by inhibiting inflammation and apoptosis via the PPARγ/HMGB1/NLRP3 axis

Endotoxin lipopolysaccharide (LPS) is one of the primary causes of myocardial injury. Propofol confers protective effects against LPS‑induced myocardial damage; however, the biological functions and mechanisms underlying propofol are not completely understood. The present study aimed to investigate the effects of propofol on LPS‑induced myocardial injury. Primary neonatal rat cardiomyocytes were treated with LPS to establish a myocardial injury model. LDH release in the culture media was measured using a LDH assay kit. The interactions between NLR family pyrin domain containing 3 (NLRP3), apoptosis‑associated speck‑like protein containing A CARD (ASC) and pro‑caspase‑1 were determined using a co‑immunoprecipitation assay. Cell viability was measured using an MTT assay, and the levels of cell apoptosis were determined using flow cytometry, JC‑1 staining (mitochondrial membrane potential) and caspase‑3 activity assays. The mRNA expression levels of TNF‑α, IL‑6, IL‑1β and IL‑18, and the protein expression levels of NLRP3, ASC, pro‑caspase‑1, caspase‑1 p10, pro‑IL‑1β, IL‑1β, pro‑IL‑18, IL‑18, high mobility group box‑1 (HMGB1) and peroxisome proliferator‑activated receptor γ (PPARγ) were analyzed using reverse transcription‑quantitative PCR and western blotting analyses, respectively. ELISAs were performed to measure the production of inflammatory mediators, including TNF‑α, IL‑6, IL‑1β and IL‑18. The present results demonstrated that pretreatment with propofol significantly attenuated LPS‑induced neonatal rat cardiomyocyte injury in a concentration‑ and time‑dependent manner. Propofol pretreatment also significantly inhibited LPS‑induced cardiomyocyte inflammation and apoptosis. The results suggested that propofol pretreatment inactivated HMGB1‑dependent NLRP3 inflammasome signaling, which involved PPARγ activation. Therefore, the results indicated that propofol reduced endotoxin‑induced cardiomyocyte injury by inhibiting inflammation and apoptosis via the PPARγ/HMGB1/NLRP3 axis, suggesting that propofol may serve as a potential therapeutic agent for septic myocardial damage.

Regulation of Mitochondrial Quality Control by Natural Drugs in the Treatment of Cardiovascular Diseases: Potential and Advantages

Mitochondria are double-membraned cellular organelles that provide the required energy and metabolic intermediates to cardiomyocytes. Mitochondrial respiratory chain defects, structure abnormalities, and DNA mutations can affect the normal function of cardiomyocytes, causing an imbalance in intracellular calcium ion homeostasis, production of reactive oxygen species, and apoptosis. Mitochondrial quality control (MQC) is an important process that maintains mitochondrial homeostasis in cardiomyocytes and involves multi-level regulatory mechanisms, such as mitophagy, mitochondrial fission and fusion, mitochondrial energy metabolism, mitochondrial antioxidant system, and mitochondrial respiratory chain. Furthermore, MQC plays a role in the pathological mechanisms of various cardiovascular diseases (CVDs). In recent years, the regulatory effects of natural plants, drugs, and active ingredients on MQC in the context of CVDs have received significant attention. Effective active ingredients in natural drugs can influence the production of energy-supplying substances in the mitochondria, interfere with the expression of genes associated with mitochondrial energy requirements, and regulate various mechanisms of MQC modulation. Thus, these ingredients have therapeutic effects against CVDs. This review provides useful information about novel treatment options for CVDs and development of novel drugs targeting MQC.

6-Gingerol protects cardiomyocytes against hypoxia-induced injury by regulating the KCNQ1OT1/miR-340-5p/ PI3K/AKT pathway

BACKGROUND

Hypoxia could induce cardiomyocytes injury and lead to heart disease. Studies have shown that 6-Gingerol has a protective effect on cardiomyocytes injury, but its molecular mechanism is still unclear.

METHODS

Cell counting kit 8 (CCK8) and flow cytometry assays were used to measure the viability and apoptosis of cardiomyocytes. Western blot (WB) analysis was performed to assess the levels of proliferation, apoptosis, and phosphatidylinositol 3- kinase/protein kinase B (PI3K/AKT) signaling pathway-related proteins. The reactive oxygen species (ROS) level, superoxide dismutase (SOD) activity and malondialdehyde (MDA) level were detected by their corresponding Assay Kits. Besides, the expression levels of potassium voltage-gated channel subfamily Q member 1 opposite strand 1 (KCNQ1OT1) and microRNA-340-5p (miR-340-5p) were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Furthermore, dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to verify the interaction between KCNQ1OT1 and miR-340-5p.

RESULTS

Hypoxia could inhibit the viability and enhance the apoptosis and oxidative stress of cardiomyocytes to induce cardiomyocytes injury, while 6-Gingerol could alleviate this effect. Overexpression of KCNQ1OT1 aggravated hypoxia-induced cardiomyocytes injury and reversed the protective effect of 6-Gingerol on cardiomyocytes injury. Besides, miR-340-5p could be sponged by KCNQ1OT1, and its overexpression could invert the promotion effect of KCNQ1OT1 overexpression on hypoxia-induced cardiomyocytes injury. Moreover, miR-340-5p expression was regulated by 6-Gingerol and KCNQ1OT1. In addition, hypoxia inactivated the PI3K/AKT signaling pathway, whereas 6-Gingerol and miR-340-5p could reverse this effect.

CONCLUSIONS

6-Gingerol could hinder the expression of KCNQ1OT1 to protect cardiomyocytes from hypoxia-induced injury through regulation of the miR-340-5p/ PI3K/AKT pathway, providing a new mechanism of 6-Gingerol protecting cardiomyocytes from injury.

Attenuation of doxorubicin-induced cardiotoxicity by cryptotanshinone detected through association analysis of transcriptomic profiling and KEGG pathway

OBJECTIVE

The cardiotoxicity of doxorubicin (DOX) reduces the quality of life and prognosis of cancer patients, and therefore its clinical application has been largely restricted. This study aimed to assess the effects of cryptotanshione (CPT) on DOX-induced rat cardiac insufficiency.

RESULTS

CPT treatment significantly suppressed apoptosis in vitro. The oral administration of CPT significantly improved cardiac function in the rat model, reduced collagen production and suppressed apoptosis and the production of reactive oxygen species in the heart tissue. Transcriptomic profiling and its relevant bioinformatics analysis showed that CPT suppressed doxorubicin-induced cardiotoxicity by inhibiting p53 signaling pathway.

CONCLUSION

Transcriptomic profiling and bioinformatics analysis can be used to evaluate the cardio-protective effect of CPT through inactivating p53 signaling pathway in the doxorubicin-mediated myocardial damage model.

METHODS

F-actin staining and flow cytometry were used to assess the effects of CPT on cardiomyocytes. In vivo, echocardiography and hemodynamic evaluation were used to assess the effects of CPT on the cardiac dysfunction in rats. Furthermore, transcriptomic profiling and bioinformatics analysis, as well as western blot analysis, were used to determine that CPT induced changes in the signaling pathways in the model.

Capsaicin Alleviates the Deteriorative Mitochondrial Function by Upregulating 14-3-3η in Anoxic or Anoxic/Reoxygenated Cardiomyocytes

Reactive oxygen species (ROS) are byproducts of a defective electron transport chain (ETC). The redox couples, GSH/GSSG and NAD⁺/NADH, play an essential role in physiology as internal defenses against excessive ROS generation by facilitating intracellular/mitochondrial (mt) redox homeostasis. Anoxia alone and anoxia/reoxygenation (A/R) are dissimilar pathological processes. In this study, we measured the impact of capsaicin (Cap) on these pathological processes using a primary cultured neonatal rat cardiomyocyte in vitro model. The results showed that overproduction of ROS was tightly associated with disturbed GSH/GSSG and NAD⁺/NADH suppressed mt complex I and III activities, decreased oxygen consumption rates, and elevated extracellular acidification rates. During anoxia or A/R period, these indices interact with each other causing the mitochondrial function to worsen. Cap protected cardiomyocytes against the different stages of A/R injury by rescuing NAD⁺/NADH, GSH/GSSG, and mt complex I/III activities and cellular energy metabolism. Importantly, Cap-mediated upregulation of 14-3-3η, a protective phosphoserine-binding protein in cardiomyocytes, ameliorated mt function caused by a disruptive redox status and an impaired ETC. In conclusion, redox pair, mt complex I/III, and metabolic equilibrium were significantly different in anoxia alone and A/R injury; Cap through upregulating 14-3-3η plays a protection against the above injury in cardiomyocyte.

Tetramethylpyrazine alleviates iron overload damage in vascular endothelium via upregulating DDAHII expression

Iron overload causes vascular endothelium damage. It has been thought to relate excessive reactive oxygen species (ROS) generation. Tetramethylpyrazine (TMP), an active ingredient of Ligusticum chuanxiong Hort, protects various cells by inhibiting oxidative stress and cascade reaction of apoptosis. However, whether TMP can increase DDAHII activity and expression against endothelial cell damage induced by iron overload, and the protective mechanism has not been elucidated. In this study, 50 μM iron dextran and 25 μM TMP were used to co-treat HUVECs for 48 h. TMP could increase cell viability and decrease LDH activity, enhance DDAHII expression and activity, p-eNOS/eNOS ratio, NO content, and reduce ADMA level. TMP also showed a strong antioxidant activity with inhibited ROS generation and oxidative stress. Moreover, TMP attenuated mitochondrial membrane potential loss, inhibited mitochondrial permeability transition pore openness, and decreased apoptosis induced by iron overload. While mentioned above, the protective effects of TMP were abolished with the addition of pAD/DDAHII-shRNA. The effects of TMP against iron overload were similar to the positive control groups, L-arginine, a competitive substrate of ADMA, or edaravone, free radical scavenger. These results signify that TMP alleviated iron overload damage in vascular endothelium via ROS/ADMA/ DDAHII/eNOS/NO pathway.

Differential Subcellular Distribution and Translocation of Seven 14-3-3 Isoforms in Response to EGF and During the Cell Cycle

Multiple isoforms of 14-3-3 proteins exist in different organisms. In mammalian cells, 14-3-3 protein has seven isoforms (α/β, ε, η, γ, σ, θ/τ, and δ/ζ), with α and δ representing the phosphorylated versions of β and ζ, respectively. While the existence of multiple isoforms may represent one more level of regulation in 14-3-3 signaling, our knowledge regarding the isoform-specific functions of 14-3-3 proteins is very limited. Determination of the subcellular localization of the different 14-3-3 isoforms could give us important clues of their specific functions. In this study, by using indirect immunofluorescence, subcellular fractionation, and immunoblotting, we studied the subcellular localization of the total 14-3-3 protein and each of the seven 14-3-3 isoforms; their redistribution throughout the cell cycle; and their translocation in response to EGF in Cos-7 cells. We showed that 14-3-3 proteins are broadly distributed throughout the cell and associated with many subcellular structures/organelles, including the plasma membrane (PM), mitochondria, ER, nucleus, microtubules, and actin fibers. This broad distribution underlines the multiple functions identified for 14-3-3 proteins. The different isoforms of 14-3-3 proteins have distinctive subcellular localizations, which suggest their distinctive cellular functions. Most notably, 14-3-3ƞ is almost exclusively localized to the mitochondria, 14-3-3γ is only localized to the nucleus, and 14-3-3σ strongly and specifically associated with the centrosome during mitosis. We also examined the subcellular localization of the seven 14-3-3 isoforms in other cells, including HEK-293, MDA-MB-231, and MCF-7 cells, which largely confirmed our findings with Cos-7 cells.

Tetramethylpyrazine Attenuates the Endotheliotoxicity and the Mitochondrial Dysfunction by Doxorubicin via 14-3-3γ/Bcl-2

Doxorubicin (Dox) with cardiotoxicity and endotheliotoxicity limits its clinical application for cancer. The toxicitic mechanism involves excess ROS generation. 14-3-3s have the protective effects on various injured tissues and cells. Tetramethylpyrazine (TMP) is an alkaloid extracted from the rhizome of Ligusticum wallichii and has multiple bioactivities. We hypothesize that TMP has the protective effects on vascular endothelium by upregulating 14-3-3γ. To test the hypothesis, Dox-induced endotheliotoxicity was used to establish vascular endothelium injury models in mice and human umbilical vein endothelial cells. The effects of TMP were assessed by determining thoracic aortic strips' endothelium-dependent dilation (EDD), as well as LDH, CK, caspase-3, SOD, CAT, GSH-Px activities and MDA level in serum, apoptotic rate, and histopathological changes of vascular tissue (in vivo). Also, cell viability, LDH and caspase-3 activities, ROS generation, levels of NAD⁺/NADH and GSH/GSSG, MMP, mPTP opening, and apoptotic rate were evaluated (in vitro). The expression of 14-3-3γ and Bcl-2, as well as phosphorylation of Bad (S112), were determined by Western blot. Our results showed that Dox-induced injury to vascular endothelium was decreased by TMP via upregulating 14-3-3γ expression in total protein and Bcl-2 expression in mitochondria, activating Bad (S112) phosphorylation, maintaining EDD, reducing LDH, CK, and caspase-3 activities, thereby causing a reduction in apoptotic rate, and histopathological changes of vascular endothelium (in vivo). Furthermore, TMP increased cell viability and MMP levels, maintained NAD⁺/NADH, GSH/GSSG balance, decreased LDH and caspase-3 activities, ROS generation, mPTP opening, and apoptotic rate (in vitro). However, the protective effects to vascular endothelium of TMP were significantly canceled by pAD/14-3-3γ-shRNA, an adenovirus that caused knockdown 14-3-3γ expression, or ABT-737, a specific Bcl-2 inhibitor. In conclusion, this study is the first to demonstrate that TMP protects the vascular endothelium against Dox-induced injury via upregulating 14-3-3γ expression, promoting translocation of Bcl-2 to the mitochondria, closing mPTP, maintaining MMP, inhibiting RIRR mechanism, suppressing oxidative stress, improving mitochondrial function, and alleviating Dox-induced endotheliotoxicity.

Tetramethylpyrazine relieves LPS-induced pancreatic β-cell Min6 injury via regulation of miR-101/MKP-1

Tetramethylpyrazine (TMP) is a traditional Chinese medicine with anti-inflammation and immunomodulatory effects. In this context, our purpose was to investigate the associated regulatory mechanisms of TMP against lipopolysaccharide (LPS)-caused pancreatic β cell Min6 injury. The injury of Min6 cells was induced by 10 μg/mL of LPS. Viability of Min6 cells was detected through CCK-8 assay, apoptosis process through flow cytometry, and the proteins involved in apoptosis through western blot. Insulin secretion was valued through the glucose-stimulated insulin secretion (GSIS) assay. microRNA-101 (miR-101) was measured through qRT-PCR. Mitogen-activated protein kinase phosphatase 1 (MKP-1) and signaling regulators was measured through western blot. We found that, TMP treatment effectively attenuated LPS-induced injury in Min6 cells by suppressing cell apoptosis and promoting insulin secretion. Further investigation revealed that TMP exerted protective effect through down-regulating miR-101, and MKP-1 was demonstrated as a target of miR-101. Moreover, TMP attenuated LPS-triggered inflammation by inactivating the JNK1/2 and NF-κB through the down-regulation of miR-101. In conclusion, our present study revealed that TMP alleviated LPS-induced injury in pancreatic β-cell Min6 injury via regulation of miR-101/MKP-1 with the bluntness of JNK1/2 and NF-κB pathways.

RETRACTED: Tetramethylpyrazine alleviates lipopolysaccharide-induced damage in ATDC5 cells via down-regulating MyD88

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief and the authors. Following the concerns raised about the background pattern of the Western Blots from Figures 7A and 7C, the authors have contacted the journal to request the retraction of the article as they were reportedly not confident of the accuracy of the data and the conclusions of the article. Given the comments of Dr Elisabeth Bik regarding this article “This paper belongs to a set of over 400 papers (as per February 2020) that share very similar Western blots with tadpole-like shaped bands, the same background pattern, and striking similarities in title structures, paper layout, bar graph design, and - in a subset - flow cytometry panels”, the journal requested the authors to provide the raw data. However, the authors were not able to fulfil this request and therefore the Editor-in-Chief decided to retract the article.

An Alkylpyrazine Synthesis Mechanism Involving l-Threonine-3-Dehydrogenase Describes the Production of 2,5-Dimethylpyrazine and 2,3,5-Trimethylpyrazine by Bacillus subtilis

Alkylpyrazines are important contributors to the flavor of traditional fermented foods. Here, we studied the synthesis mechanisms of 2,5-dimethylpyrazine (2,5-DMP) and 2,3,5-trimethylpyrazine (TMP). Substrate addition, whole-cell catalysis, stable isotope tracing experiments, and gene manipulation revealed that l-threonine is the starting point involving l-threonine-3-dehydrogenase (TDH) and three uncatalyzed reactions to form 2,5-DMP. TDH catalyzes the oxidation of l-threonine. The product of this reaction is l-2-amino-acetoacetate, which is known to be unstable and can decarboxylate to form aminoacetone. It is proposed that aminoacetone spontaneously converts to 2,5-DMP in a pH-dependent reaction, via 3,6-dihydro-2,5-DMP. 2-Amino-3-ketobutyrate coenzyme A (CoA) ligase (KBL) catalyzes the cleavage of l-2-amino-acetoacetate, the product of TDH, into glycine and acetyl-CoA in the presence of CoA. Inactivation of KBL could improve the production of 2,5-DMP. Besides 2,5-DMP, TMP can also be generated by Bacillus subtilis 168 by using l-threonine and d-glucose as the substrates and TDH as the catalytic enzyme.IMPORTANCE Despite alkylpyrazines' contribution to flavor and their commercial value, the synthesis mechanisms of alkylpyrazines by microorganisms remain poorly understood. This study revealed the substrate, intermediates, and related enzymes for the synthesis of 2,5-dimethylpyrazine (2,5-DMP), which differ from the previous reports about the synthesis of 2,3,5,6-tetramethylpyrazine (TTMP). The synthesis mechanism described here can also explain the production of 2,3,5-trimethylpyrazine (TMP). The results provide insights into an alkylpyrazine's synthesis pathway involving l-threonine-3-dehydrogenase as the catalytic enzyme and l-threonine as the substrate.

Nutritional preconditioning induced by astragaloside Ⅳ on isolated hearts and cardiomyocytes against myocardial ischemia injury via improving Bcl-2-mediated mitochondrial function

Ischemic preconditioning and pharmacological preconditioning are common strategies to prevent lethal myocardial injury, especially nutritional preconditioning (NPC). In this study, we investigated the effects of astragaloside IV (Ast), as an NPC agent, on myocardium suffered anoxia/reoxygenation (A/R) injury. Rats received 5 mg/kg Ast daily for 3 weeks by intragastric administration. Then, hearts were harvested and underwent A/R treatment using a Langendorff apparatus. Ast- pretreatment significantly promoted functional recovery of the myocardium, reduced infarct size, and oxidative stress, and decreased the apoptotic index. Similar findings were demonstrated in H9c2 cardiomyocytes that were pretreated with Ast for 24 h. Moreover, Ast-pretreatment significantly upregulated Bcl-2 expression, especially in mitochondria. The effects of Ast treatment against A/R injury were also reflected by increased antioxidant potential, inhibited reactive oxygen species (ROS) burst, increased oxygen consumption rate, maintained mitochondrial membrane potential (MMP), inhibited mitochondrial permeability transition pore (mPTP) opening, and prevented apoptosis. Selective inhibition of Bcl-2 by ABT-737 decreased myocardial injury protection of Ast. Ast-pretreatment resulted in NPC- related effects against A/R, and mitochondria may be the target of a cascade of events elicited by upregulating Bcl-2 expression, promoting translocation of Bcl-2 into mitochondria, maintaining MMP, inhibiting ROS bursts, thereby leading to recovery of mitochondrial respiration, preventing mPTP opening, decreasing cytochrome C release, preventing apoptosis, and ultimately alleviating myocardial injury.

Thyroxine Affects Lipopolysaccharide-Induced Macrophage Differentiation and Myocardial Cell Apoptosis via the NF-κB p65 Pathway Both In Vitro and In Vivo

Background

Numerous studies have demonstrated that the inflammatory response is involved in the progression of lipopolysaccharide- (LPS-) induced myocardial cell apoptosis. Accumulating evidence has shown that thyroxine participates in diseases by downregulating the inflammatory response. This study aimed at investigating whether thyroxine alleviates LPS-induced myocardial cell apoptosis.

Methods

Bone marrow-derived macrophages (Mø) were treated with LPS and thyroxine, and Mø differentiation and Mø-related cytokine expression were measured. The effect of Mø differentiation on mouse cardiomyocyte (MCM) apoptosis was also detected in vitro. In addition, C57BL/6 mice underwent thyroidectomy and were treated with LPS 35 days later; subsequently, Mø differentiation and myocardial cell apoptosis in hearts were analyzed. To determine whether the nuclear factor-kappa B (NF-κB) p65 pathway mediates the effect of thyroxine on Mø differentiation and myocardial cell apoptosis, the specific NF-κB p65 pathway inhibitor JSH-23 was administered to mice that underwent a thyroidectomy.

Results

Levothyroxine treatment significantly reduced the activation of the NF-κB p65 pathway, decreased M1 macrophage (Mø1) differentiation and Mø1-related cytokine mRNA levels in LPS-treated Mø, and increased M2 macrophage (Mø2) differentiation and Mø2-related cytokine mRNA expression. The protective effects of levothyroxine on MCM apoptosis mediated by LPS-treated Mø were alleviated by JSH-23. In mice, thyroidectomy aggravated LPS-induced cardiac injury and cardiac dysfunction, further promoted NF-κB p65 activation, and increased cardiac Mø1 expression and myocardial cell apoptosis but decreased cardiac Mø2 expression. JSH-23 treatment significantly ameliorated the thyroidectomy-induced increases in myocardial cell apoptosis and Mø differentiation.

Conclusions

Thyroxine alleviated the Mø1/Mø2 imbalance, reduced the inflammatory response, decreased myocardial cell apoptosis, and protected against cardiac injury and cardiac dysfunction in LPS-treated mice. Thyroxine may be a novel therapeutic strategy to prevent and treat LPS-induced cardiac injury.

Curcumin attenuates doxorubicin-induced cardiotoxicity via suppressing oxidative stress and preventing mitochondrial dysfunction mediated by 14-3-3γ

Doxorubicin (Dox) induces cardiotoxicity, thereby limiting its clinical application for chemotherapy of cancer. The mechanism of cardiotoxicity includes the production of excess intracellular ROS. 14-3-3s have been found to protect the myocardium against various types of injury. Curcumin (Cur) is a polyphenolic compound that is derived from turmeric and has multiple bioactivities, including anti-oxidative and radical-scavenging activities that exert cytoprotection. We hypothesize that the cardioprotective effects of Cur are exerted by regulating 14-3-3γ. To test the hypothesis, Dox-induced cardiotoxicity was used to establish an in vivo myocardial injury model in mice (in vivo) and primary cardiomyocytes (in intro). The effects of Cur were assessed by determining the heart rate and ECG's ST segments, as well as lactate dehydrogenase (LDH) and creatine kinase (CK) activities in the serum, caspase-3 activity, apoptosis rate, and histopathological changes of the myocardium (in vivo). In addition, cell viability, LDH, SOD, CAT, GPx, and caspase-3 activities, levels of ROS, MDA, and MMP, mPTP opening, and the apoptosis rate (in vitro) were evaluated. The expression of 14-3-3γ and Bcl-2 as well as the phosphorylation levels of Bad (S112) were determined by western blot analysis. Our results showed that Dox-induced injury to the myocardium was decreased by Cur treatment via upregulating the protein expression of 14-3-3γ in total protein and Bcl-2 expression on mitochondria, activating Bad (S112) phosphorylation, reducing the heart rate and ST segment, and reducing LDH and CK activities in the serum, thereby causing a reduction in caspase-3 activity, the apoptosis rate, and histopathological changes of the myocardium (in vivo). Furthermore, Dox treatment increased cell viability and MMP levels, decreased LDH and caspase-3 activity, ROS levels, mPTP opening, and the apoptosis rate (in vitro). However, the cardioprotective effects of Cur were attenuated by pAD/14-3-3γ-shRNA, an adenovirus that caused a knock-down of intracellular 14-3-3γ expression. In conclusion, this is the first study to demonstrate that Cur protected the myocardium against Dox-induced injury via upregulating 14-3-3γ expression, thereby promoting the translocation of Bcl-2 to mitochondria, suppressing oxidative stress, and improving mitochondrial function.