Calenduloside E Ameliorates Myocardial Ischemia-Reperfusion Injury through Regulation of AMPK and Mitochondrial OPA1

Excitotoxicity, Oxytosis/Ferroptosis, and Neurodegeneration: Emerging Insights into Mitochondrial Mechanisms

Mitochondrial dysfunction plays a pivotal role in the development of age-related diseases, particularly neurodegenerative disorders. The etiology of mitochondrial dysfunction involves a multitude of factors that remain elusive. This review centers on elucidating the role(s) of excitotoxicity, oxytosis/ferroptosis and neurodegeneration within the context of mitochondrial bioenergetics, biogenesis, mitophagy and oxidative stress and explores their intricate interplay in the pathogenesis of neurodegenerative diseases. The effective coordination of mitochondrial turnover processes, notably mitophagy and biogenesis, is assumed to be critically important for cellular resilience and longevity. However, the age-associated decrease in mitophagy impedes the elimination of dysfunctional mitochondria, consequently impairing mitochondrial biogenesis. This deleterious cascade results in the accumulation of damaged mitochondria and deterioration of cellular functions. Both excitotoxicity and oxytosis/ferroptosis have been demonstrated to contribute significantly to the pathophysiology of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's Disease (HD), Amyotrophic Lateral Sclerosis (ALS) and Multiple Sclerosis (MS). Excitotoxicity, characterized by excessive glutamate signaling, initiates a cascade of events involving calcium dysregulation, energy depletion, and oxidative stress and is intricately linked to mitochondrial dysfunction. Furthermore, emerging concepts surrounding oxytosis/ferroptosis underscore the importance of iron-dependent lipid peroxidation and mitochondrial engagement in the pathogenesis of neurodegeneration. This review not only discusses the individual contributions of excitotoxicity and ferroptosis but also emphasizes their convergence with mitochondrial dysfunction, a key driver of neurodegenerative diseases. Understanding the intricate crosstalk between excitotoxicity, oxytosis/ferroptosis, and mitochondrial dysfunction holds potential to pave the way for mitochondrion-targeted therapeutic strategies. Such strategies, with a focus on bioenergetics, biogenesis, mitophagy, and oxidative stress, emerge as promising avenues for therapeutic intervention.

Pentacyclic triterpenes, potential novel therapeutic approaches for cardiovascular diseases

Cardiovascular diseases (CVDs) involve dysfunction of the heart and blood vessels and have become major health concerns worldwide. Multiple mechanisms may be involved in the occurrence and development of CVDs. Although therapies for CVDs are constantly being developed and applied, the incidence and mortality of CVDs remain high. The roles of natural compounds in CVD treatment are being explored, providing new approaches for the treatment of CVD. Pentacyclic triterpenes are natural compounds with a basic nucleus of 30 carbon atoms, and they have been widely studied for their potential applications in the treatment of CVDs, to which various pharmacological activities contribute, including anti-inflammatory, antioxidant, and antitumor effects. This review introduces the roles of triterpenoids in the prevention and treatment of CVDs, summarizes their potential underlying mechanisms, and provides a comprehensive overview of the therapeutic potential of triterpenoids in the management of CVDs.

Novel glycosidase from Paenibacillus lactis 154 hydrolyzing the 28-O-β-D-glucopyranosyl ester bond of oleanane-type saponins

Oleanane-type ginsenosides are a class of compounds with remarkable pharmacological activities. However, the lack of effective preparation methods for specific rare ginsenosides has hindered the exploration of their pharmacological properties. In this study, a novel glycoside hydrolase PlGH3 was cloned from Paenibacillus lactis 154 and heterologous expressed in Escherichia coli. Sequence analysis revealed that PlGH3 consists of 749 amino acids with a molecular weight of 89.5 kDa, exhibiting the characteristic features of the glycoside hydrolase 3 family. The enzymatic characterization results of PlGH3 showed that the optimal reaction pH and temperature was 8 and 50 °C by using p-nitrophenyl-β-D-glucopyranoside as a substrate, respectively. The Km and kcat values towards ginsenoside Ro were 79.59 ± 3.42 µM and 18.52 s-1, respectively. PlGH3 exhibits a highly specific activity on hydrolyzing the 28-O-β-D-glucopyranosyl ester bond of oleanane-type saponins. The mechanism of hydrolysis specificity was then presumably elucidated through molecular docking. Eventually, four kinds of rare oleanane-type ginsenosides (calenduloside E, pseudoginsenoside RP1, zingibroside R1, and tarasaponin VI) were successfully prepared by biotransforming total saponins extracted from Panax japonicus. This study contributes to understanding the mechanism of enzymatic hydrolysis of the GH3 family and provides a practical route for the preparation of rare oleanane-type ginsenosides through biotransformation. KEY POINTS: • The glucose at C-28 in oleanane-type saponins can be directionally hydrolyzed. • Mechanisms to interpret PlGH3 substrate specificity by molecular docking. • Case of preparation of low-sugar alternative saponins by directed hydrolysis.

FAM3A Deficiency - Induced Mitochondrial Dysfunction Underlies Post-Infarct Mortality and Heart Failure

Mitochondrial protein sequence similarity 3 gene family member A (FAM3A) plays important roles in the electron transfer chain, while its functions in the heart are still unknown. This study aims to explore the roles and mechanisms of FAM3A after myocardial infarction (MI). FAM3A-deficient (Fam3a-/-) mice were implemented with MI injury and showed lower survival rates at 4 weeks as well as decreased cardiac systolic function. Isolated cardiomyocytes of Fam3a-/- mice showed reduced basal, ATP-linked respiration and respiratory reserve compared to that of wild-type mice. Transmission electron microscopy studies showed Fam3a-/- mice had a larger size and elevated density of mitochondria. FAM3A deficiency also induced elevated mitochondrial Ca2+, higher opening level of mPTP, lower mitochondrial membrane potential and elevated apoptotic rates. Further analyses demonstrated that mitochondrial dynamics protein Opa1 contributed to the effects of FAM3A in cardiomyocytes. Our study discloses the important roles of mitochondrial protein FAM3A in the heart.

Exercise Attenuates Myocardial Ischemia-Reperfusion Injury by Regulating Endoplasmic Reticulum Stress and Mitophagy Through M2 Acetylcholine Receptor

Aims: Adaptive changes in the heart by exercise have been shown to reduce the risk of cardiovascular disease, and M2 Acetylcholine receptor (M2AChR), a receptor abundantly present on cardiac parasympathetic nerves, is closely associated with the development of cardiovascular disease. The present study intends to investigate whether exercise can regulate endoplasmic reticulum stress (ERS) and mitophagy through M2AChR to resist myocardial ischemia-reperfusion (I/R) injury and to elucidate its mechanism of action. Results: Exercise enhanced parasympathetic nerve function and increased myocardial M2AChR protein expression in I/R rats. In addition, it promoted the protein expression of MFN2 and inhibited the expression of Drp1, Chop, PINK1/Parkin, and PERK/eIF2α/ATF4 signaling pathways, effectively reducing mitophagy, ERS, and apoptosis. At the cellular level, 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR) reduced hypoxia/reoxygenation (H/R)-induced ERS through the downregulated expression of PERK/eIF2α/ATF4 pathway proteins in H9C2 cardiomyocytes. When intervened with M2AChR inhibitors, the levels of ERS and phosphorylation levels of the PERK/eIF2α/ATF4 pathway were increased in H/R cells. Innovation and Conclusion: Exercise intervention activated the parasympathetic state in rats. It inhibited myocardial mitophagy and ERS levels, and reduced myocardial apoptosis through M2AChR, thereby resisting I/R-induced myocardial injury and improving cardiac function. Antioxid. Redox Signal. 40, 209-221.

Effect and possible mechanisms of saponins in Chinese herbal medicine exerts for the treatment of myocardial ischemia-reperfusion injury in experimental animal: a systematic review and meta-analysis

Introduction

Preventing ischemia-reperfusion injury is the main direction of myocardial infarction treatment in the convalescent stage. Some studies have suggested that saponins in Traditional Chinese medicine (TCM) preparations can protect the myocardium by various mechanisms. Our meta-analysis aims to evaluate the efficacy of TCM saponins in treating myocardial ischemia-reperfusion injury (MIRI) and to summarize the potential molecular mechanisms further.

Methods

We conducted a literature search in six electronic databases [Web of Science, PubMed, Embase, Cochrane Library, Sinomed, China National Knowledge Infrastructure (CNKI)] until October 2022.

Results

Seventeen eligible studies included 386 animals (254 received saponins and 132 received vehicles). The random effect model is used to calculate the combined effect. The effect size is expressed as the weighted average difference (WMD) and 95% confidence interval (CI). Compared with placebo, saponins preconditioning reduced infarct size after MIRI significantly (WMD: -3.60,95% CI: -4.45 to -2.74, P < 0.01, I2: 84.7%, P < 0.001), and significantly increased EF (WMD: 3.119, 95% CI: 2.165 to 4.082, P < 0.01, I2: 82.9%, P < 0.0 L) and FS (WMD: 3.157, 95% CI: 2.218 to 4.097, P < 0.001, I2: 81.3%, P < 0.001).

Discussion

The results show that the pre-administration of saponins from TCM has a significant protective effect on MIRI in preclinical studies, which provides an application prospect for developing anti-MIRI drugs with high efficiency and low toxicity.

Targeting Mitochondrial Dysfunction in Neurodegenerative Diseases: Expanding the Therapeutic Approaches by Plant-Derived Natural Products

Mitochondria are the primary source of energy production in neurons, supporting the high energy consumption of the nervous system. Inefficient and dysfunctional mitochondria in the central nervous system have been implicated in neurodegenerative diseases. Therefore, targeting mitochondria offers a new therapeutic opportunity for neurodegenerative diseases. Many recent studies have proposed that plant-derived natural products, as pleiotropic, safe, and readily obtainable sources of new drugs, potentially treat neurodegenerative diseases by targeting mitochondria. In this review, we summarize recent advances in targeting mitochondria in neurotherapeutics by employing plant-derived natural products. We discuss the mechanism of plant-derived natural products according to their mechanism of action on mitochondria in terms of regulating biogenesis, fusion, fission, bioenergetics, oxidative stress, calcium homeostasis, membrane potential, and mitochondrial DNA stability, as well as repairing damaged mitochondria. In addition, we discuss the potential perspectives and challenges in developing plant-derived natural products to target mitochondria, highlighting the clinical value of phytochemicals as feasible candidates for future neurotherapeutics.

RBM3 interacts with Raptor to regulate autophagy and protect cardiomyocytes from ischemia-reperfusion-induced injury

Acute myocardial infarction (AMI) is a common disease with high morbidity and mortality worldwide. However, postinfarction pathogenesis remains unclear, and it is particularly important to identify new therapeutic targets. The RNA-binding motif protein RBM3 (also known as cold-inducible protein) is known to promote translation and is associated with tumor proliferation and neuroprotection. However, little is known about the biological effects of RBM3 on myocardial infarction. In the present study, we found that RBM3 expression was significantly upregulated in ischemia-reperfusion (I/R) condition and downregulation of RBM3 inhibited autophagy and promoted apoptosis in cardiomyocytes. We confirmed that RBM3 interacts with Raptor to regulate the autophagy pathway. Taken together, these findings illustrate the protective effects of RBM3 against I/R-induced myocardial apoptosis through the autophagy pathway.

AMPK-dependent phosphorylation of MTFR1L regulates mitochondrial morphology

Mitochondria are dynamic organelles that undergo membrane remodeling events in response to metabolic alterations to generate an adequate mitochondrial network. Here, we investigated the function of mitochondrial fission regulator 1-like protein (MTFR1L), an uncharacterized protein that has been identified in phosphoproteomic screens as a potential AMP-activated protein kinase (AMPK) substrate. We showed that MTFR1L is an outer mitochondrial membrane-localized protein modulating mitochondrial morphology. Loss of MTFR1L led to mitochondrial elongation associated with increased mitochondrial fusion events and levels of the mitochondrial fusion protein, optic atrophy 1. Mechanistically, we show that MTFR1L is phosphorylated by AMPK, which thereby controls the function of MTFR1L in regulating mitochondrial morphology both in mammalian cell lines and in murine cortical neurons in vivo. Furthermore, we demonstrate that MTFR1L is required for stress-induced AMPK-dependent mitochondrial fragmentation. Together, these findings identify MTFR1L as a critical mitochondrial protein transducing AMPK-dependent metabolic changes through regulation of mitochondrial dynamics.

Calenduloside E alleviates cerebral ischemia/reperfusion injury by preserving mitochondrial function

Calenduloside E (CE) isolated from Aralia elata (Miq.) Seem. is a natural triterpenoid saponin that can reportedly ameliorate myocardial ischemia/reperfusion injury. However, its potential roles and mechanism in cerebral ischemia/reperfusion injury are barely understood. In this study, we established an oxygen-glucose deprivation/reoxygenation (OGD/R) model in HT22 cells. We found that CE significantly attenuated the OGD/R-induced inhibition of cell viability and apoptotic cell death in HT22 cells. Moreover, CE treatment significantly ameliorated OGD/R-induced mitochondrial fission by inhibiting mitochondrial dynamin-related protein 1 (Drp1) recruitment and increasing Drp1 phosphorylation at Ser637. CE treatment significantly ameliorated OGD/R-induced mitochondrial dysfunction by increasing the mitochondrial membrane potential and reducing the mitochondrial ROS and cellular calcium accumulation. Moreover, CE treatment significantly inhibited the OGD/R-induced release of mitochondrial Cytochrome C and increase in Bax, Cleaved-caspase3 and Cleaved-caspase9 protein levels, whereas CE treatment significantly reversed the OGD/R-induced decrease in Bcl-2 and full length of caspase3 and caspase9 protein levels. In vivo, we found that CE treatment significantly ameliorated ischemic/hypoxic-induced brain infarct volume, neurological deficits, and neuronal apoptosis in mice after middle cerebral artery occlusion and reperfusion. CE treatment also significantly ameliorated the mitochondrial transmembrane potential, decreased Cytochrome C release, and reversed the increase in Bax, Cleaved-caspase3 and Cleaved-caspase9 protein levels and the decrease in Bcl-2 and full length of caspase3 and caspase9 protein levels induced by cerebral ischemia/reperfusion (I/R). All these results indicated that CE treatment exerted a neuroprotective effect by ameliorating mitochondrial dysfunction during cerebral I/R injury.

AMPK Activation Alleviates Myocardial Ischemia-Reperfusion Injury by Regulating Drp1-Mediated Mitochondrial Dynamics

Mitochondrial dysfunction is a salient feature of myocardial ischemia/reperfusion injury (MIRI), while the potential mechanism of mitochondrial dynamics disorder remains unclear. This study sought to explore whether activation of Adenosine monophosphate-activated protein kinase (AMPK) could alleviate MIRI by regulating GTPase dynamin-related protein 1 (Drp1)-mediated mitochondrial dynamics. Isolated mouse hearts in a Langendorff perfusion system were subjected to ischemia/reperfusion (I/R) treatment, and H9C2 cells were subjected to hypoxia /reoxygenation (H/R) treatment in vitro. The results showed that AICAR, the AMPK activator, could significantly improve the function of left ventricular, decrease arrhythmia incidence and myocardial infarction area of isolated hearts. Meanwhile, AICAR increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) content in myocardial homogenate. Mechanistically, AICAR inhibited the phosphorylation of Drp1 at Ser 616 while enhanced phosphorylation of Drp1 at Ser 637. In addition, AICAR reduced the expression of inflammatory cytokines including TNF-ɑ, IL-6, and IL-1β, as well as mitochondrial fission genes Mff and Fis1, while improved the expression of mitochondrial fusion genes Mfn1 and Mfn2. Similar results were also observed in H9C2 cells. AICAR improved mitochondrial membrane potential (MMP), reduced reactive oxygen species (ROS) production, and inhibited mitochondrial damage. To further prove if Drp1 regulated mitochondrial dynamics mediated AMPK protection effect, the mitochondrial fission inhibitor Mdivi-1 was utilized. We found that Mdivi-1 significantly improved MMP, inhibited ROS production, reduced the expression of TNF-a, IL-6, IL-1β, Fis1, and Mff, and improved the expression of Mfn1 and Mfn2. However, the protection effect of Mdivi-1 was not reversed by AMPK inhibitor Compound C. In conclusion, this study confirmed that activation of AMPK exerted the protective effects on MIRI, which were largely dependent on the inhibition of Drp1-mediated mitochondrial fission.

Mitochondrial Dynamics and Mitophagy in Cardiometabolic Disease

Mitochondria play a key role in cellular metabolism. Mitochondrial dynamics (fusion and fission) and mitophagy, are critical to mitochondrial function. Fusion allows organelles to share metabolites, proteins, and mitochondrial DNA, promoting complementarity between damaged mitochondria. Fission increases the number of mitochondria to ensure that they are passed on to their offspring during mitosis. Mitophagy is a process of selective removal of excess or damaged mitochondria that helps improve energy metabolism. Cardiometabolic disease is characterized by mitochondrial dysfunction, high production of reactive oxygen species, increased inflammatory response, and low levels of ATP. Cardiometabolic disease is closely related to mitochondrial dynamics and mitophagy. This paper reviewed the mechanisms of mitochondrial dynamics and mitophagy (focus on MFN1, MFN2, OPA1, DRP1, and PINK1 proteins) and their roles in diabetic cardiomyopathy, myocardial infarction, cardiac hypertrophy, heart failure, atherosclerosis, and obesity.

Protective Effect and Mechanism of Traditional Chinese Medicine on Myocardial Ischemia Reperfusion Injury

After acute myocardial infarction, early restoration of myocardial perfusion by thrombolysis or percutaneous coronary intervention is the most effective way to reduce the size of myocardial infarction and improve clinical outcomes. However, recovery of blood flow to the ischemic myocardium may cause ischemia-reperfusion (I/R) injury, a phenomenon that instead reduces the efficacy of myocardial reperfusion. Traditional Chinese medicine (TCM) has long been used for the treatment of cardiovascular diseases and has shown remarkable efficacy. Many studies have shown that some TCMs and their active components can exert protective effects against myocardial I/R injury through different mechanisms. This review summarized the protective mechanisms and current research advances of TCMs in myocardial I/R injury.

De Novo Biosynthesis of Oleanane-Type Ginsenosides in Saccharomyces cerevisiae Using Two Types of Glycosyltransferases from Panax ginseng

Oleanane-type ginsenosides are highly biologically active substances in Panax ginseng, a popular Chinese dietary plant. Lack of key enzymes for glycosylation reactions has hindered de novo synthesis of these bioactive molecules. We mined candidate glycosyltransferases (GTs) of the ginseng database by combining key metabolites and transcriptome coexpression analyses and verified their function using in vitro enzymatic assays. The PgCSyGT1, a cellulose synthase-like GT rather than a UDP-dependent glucuronosyltransferase (UGT), was verified as the key enzyme for transferring a glucuronosyl moiety to the free C3-OH of oleanolic acid to synthesize calenduloside E. Two UGTs (PgUGT18 and PgUGT8) were first identified as, respectively, catalyzing the glycosylation reaction of the second sugar moiety of C3 and the C28 in the oleanane-type ginsenoside biosynthetic pathway. Then, we integrated these GTs in combinations into Saccharomyces cerevisiae genome and realized de novo biosynthesis of oleanane-type ginsenosides with a yield of 1.41 μg/L ginsenoside Ro in shake flasks. This report provides a basis for effective biosynthesis of diverse oleanane-type ginsenosides in microbial cell factories.

Role of GTPase-Dependent Mitochondrial Dynamins in Heart Diseases

Heart function maintenance requires a large amount of energy, which is supplied by the mitochondria. In addition to providing energy to cardiomyocytes, mitochondria also play an important role in maintaining cell function and homeostasis. Although adult cardiomyocyte mitochondria appear as independent, low-static organelles, morphological changes have been observed in cardiomyocyte mitochondria under stress or pathological conditions. Indeed, cardiac mitochondrial fission and fusion are involved in the occurrence and development of heart diseases. As mitochondrial fission and fusion are primarily regulated by mitochondrial dynamins in a GTPase-dependent manner, GTPase-dependent mitochondrial fusion (MFN1, MFN2, and OPA1) and fission (DRP1) proteins, which are abundant in the adult heart, can also be regulated in heart diseases. In fact, these dynamic proteins have been shown to play important roles in specific diseases, including ischemia-reperfusion injury, heart failure, and metabolic cardiomyopathy. This article reviews the role of GTPase-dependent mitochondrial fusion and fission protein-mediated mitochondrial dynamics in the occurrence and development of heart diseases.