A novel PGAM5 inhibitor LFHP-1c protects blood-brain barrier integrity in ischemic stroke

LFHP-1c Attenuates Hepatocellular Carcinoma Viability In Vitro Independent of PGAM5

BACKGROUND/OBJECTIVES

Upregulation of phosphoglycerate mutase 5 (PGAM5) is correlated with reduced survival outcomes in hepatocellular carcinoma (HCC). PGAM5 knockdown or knockout attenuates HCC growth in in vitro and in vivo models. A novel small molecule inhibitor of PGAM5, LFHP-1c, has recently been characterized. The objective of this study was to determine if LFHP-1c effectively reduces HCC viability in cell models.

METHODS

The hepatoma and HCC cell lines, HepG2 and HuH7, respectively, were treated with LFHP-1c. Label-free imaging was used to quantify growth. Cellular viability and reactive oxygen species (ROS) production were measured using luminescent or fluorescent assays. Expression of antioxidant and metabolic proteins was measured by immunoblot. HepG2 and HuH7 PGAM5 knockout cell lines were used as negative controls.

RESULTS

Treatment with LFHP-1c reduced cell growth and viability in HepG2 and HuH7 cell lines. Reactive oxygen species production was upregulated in both wild-type and PGAM5 knockout cell lines following LFHP-1c exposure. Cell viability was reduced following LFHP-1c treatment in PGAM5 knockout cell lines.

CONCLUSIONS

LFHP-1c reduces hepatoma and HCC viability and enhances ROS production, but these effects are independent of PGAM5.

Pre-ischaemic empagliflozin treatment attenuates blood-brain barrier disruption via β-catenin mediated protection of cerebral endothelial cells

AIMS

Microvascular endothelial cells dysfunction can significantly worsen ischaemic stroke outcomes by disrupting tight junctions and increasing the acquisition of adhesion molecules, accelerating blood-brain barrier (BBB) disruption and pro-inflammatory response. The identification of drugs that improve endothelial cell function may be crucial for ischaemic stroke. It has been validated that empagliflozin (EMPA), a novel antidiabetic drug, protects endothelial cells regardless of the diabetic status of the patient. However, the impact of EMPA on stroke outcomes is unclear. We hypothesized that EMPA would exert a beneficial effect on ischaemic stroke outcome by protecting microvascular endothelial cells against tight junction disruption and the increase of adhesion molecules.

METHODS AND RESULTS

Young adult male mice were administered with EMPA or vehicle (dimethyl sulfoxide) daily for 7 days before being subjected to transient middle cerebral artery occlusion (tMCAO). Neurological deficits were evaluated for up to 28 days post-tMCAO. Infarct volume, BBB disruption, and inflammatory status were assessed 1 day after tMCAO.bEnd.3 cells and primary brain microvascular endothelial cells were treated with EMPA or vehicle under oxygen and glucose deprivation/reperfusion (OGD/R), and the lactate dehydrogenase release, transendothelial electrical resistance, leakage of fluorescein isothiocyanate-dextran, and tight junction and adhesion molecules proteins were examined. Mechanistic studies probing the effect of EMPA on endothelial cells were conducted by RNA-seq. EMPA treatment before ischaemia markedly improved infarct volume, BBB disruption, and inflammation 1-day post-tMCAO, and further enhanced neurobehavioral function up to 28 days. Pre-treatment of EMPA attenuated endothelial cell dysfunction under OGD/R conditions. In mechanistic terms, RNA-seq data from isolated cerebral microvessels revealed that the Wnt/β-catenin signalling pathway was preserved in the EMPA group, in contrast to the vehicle group. Pre-treatment with EMPA inhibited β-catenin ubiquitination and promoted β-catenin translocation from the cytoplasm to the nucleus to improve endothelial cell function. Importantly, the β-catenin inhibitor XAV-939 eliminated this protective function of EMPA.

CONCLUSION

EMPA administration before tMCAO attenuated ischaemia/reperfusion-induced BBB disruption and inflammation via β-catenin-mediated protection of cerebral microvascular endothelial cells. Therefore, EMPA shows potential for improving stroke outcomes as an adjunctive preventive strategy.

Alpha‑Asarone Ameliorates Neuronal Injury After Ischemic Stroke and Hemorrhagic Transformation by Attenuating Blood-Brain Barrier Destruction, Promoting Neurogenesis, and Inhibiting Neuroinflammation

Recombinant tissue-type plasminogen activator (rt-PA), the primary drug for acute ischemic stroke (IS), has a narrow therapeutic window and carries a potential risk of hemorrhagic transformation (HT). Without rt-PA administration, patients may suffer permanent cerebral ischemia. Alpha-asarone (ASA), a natural compound derived from Acorus tatarinowii Schott, exhibits diverse neuropharmacological effects. This study aims to investigate whether ASA could improve outcomes in IS and be used to mitigate HT induced by rt-PA. We employed models of permanent middle cerebral artery occlusion (pMCAO) and photothrombotic cortical injury (PCI) to investigate both the therapeutic efficacy and underlying mechanisms of ASA during the acute and recovery periods following IS, respectively. Additionally, Sprague-Dawley rats were subjected to rt-PA treatment at 6-h post-PCI to mimic HT (rt-PA-HT). Our results revealed three key findings: (1) ASA demonstrated therapeutic effects in the acute phase of pMCAO rats by alleviating blood-brain barrier damage through inhibition of glial cell-mediated neuroinflammation; (2) administration of ASA 24 h after stroke ameliorated the neurological damage during the recovery phase in PCI mice by promoting neurogenesis via activation of the BDNF/ERK/CREB signaling pathway; (3) ASA attenuated rt-PA-HT injury by modulating the NLRP3/Caspase1/IL-1β and IL-18 pathways. Overall, our findings suggest that ASA mitigates neuronal injury following IS and HT, positioning it as a promising candidate for treating these conditions.

Inhibition of PGAM5 hyperactivation reduces neuronal apoptosis in PC12 cells and experimental vascular dementia rats

PURPOSE

The incidence of vascular dementia (VaD), as one of the main types of dementia in old age, has been increasing year by year, and exploring its pathogenesis and seeking practical and effective treatment methods are undoubtedly the key to solving this problem. Phosphoglycerate translocase 5 (PGAM5), as a crossroads of multiple signaling pathways, can lead to mitochondrial fission, which in turn triggers the onset and development of necroptosis, and thus PGAM5 may be a novel target for the prevention and treatment of vascular dementia.

METHODS

Animal model of vascular dementia was established by Two-vessel occlusion (2-VO) method, and cellular model of vascular dementia was established by oxygen glucose deprivation (OGD) method. Neuronal damage was detected in vivo and in vitro in different groups using different concentrations of the PGAM5-specific inhibitor LFHP-1c, and necroptosis and mitochondrial dynamics-related factors were determined.

RESULTS

In vivo experiments, 10 mg/kg-1 and 20 mg/kg-1 LFHP-1c improved cognitive deficits, reduced neuronal edema and vacuoles, increased the number of nissl bodies, and it could modulate the expression of Caspase family and Bcl-2 family related proteins and mRNAs and ameliorate neuronal damage. Simultaneously, in vitro experiments, 5 μM, 10 μM and 20 μM LFHP-1c increased the activity and migration number of model cells, reduced the number of apoptotic cells, ameliorated the excessive accumulation of intracellular reactive oxygen species, inhibited the over-activation of caspase-family and Bcl-2-family related proteins and mRNAs, and improved the mitochondrial dynamics of the fission and fusion states. Moreover, in vivo and in vitro experiments have shown that LFHP-1c can also upregulate the expression level of BDNF, inhibit the expression content of TNF-α and ROS, regulate the expression of proteins and mRNAs related to the RIPK1/RIPK3/MLKL pathway and mitochondrial dynamics, and reduce neuronal apoptosis.

CONCLUSIONS

Inhibition of PGAM5 expression level can reduce neuronal damage caused by chronic cerebral ischemia and hypoxia, which mainly prevents necroptosis by targeting the RIPK1/RIPK3/MLKL signaling pathway and regulates the downstream mitochondrial dynamics homeostasis system to prevent excessive mitochondrial fission, thus improving cognition and exerting cerebroprotective effects.

Physiological and pathological roles of PGAM5: An update and future trend

PGAM5, a phosphatase found in mitochondria, is crucial for mitochondrial quality control (MQC) through its regulation on mitochondrial dynamics, biogenesis, and mitophagy. Previous studies have shown its involvement in multiple regulated cell deaths (RCDs), including apoptosis, necroptosis, and pyroptosis. The objective of this review is to enhance our comprehension of the involvement of PGAM5 in MQC and RCDs. Additionally, we summarize some novel roles of PGAM5 in cellular senescence, lipid metabolism, and immune response modulation in recent studies. Finally, we discuss PGAM5's contribution to the pathological state of cardiovascular, hepatic, neurological, and neoplastic diseases, offering potential perspectives for future research.

Targeting PGAM5 attenuates airway inflammation in asthma by inhibiting HMGB1 release in bronchial epithelium

Previous studies have demonstrated that high-mobility group box protein 1(HMGB1) was increased and released to the extracellular and participated in the pathogenesis of steroid-insensitive asthma induced by toluene diisocyanate (TDI). Mitochondrial dysfunction of bronchial epithelia is a critical feature in TDI asthma. However, whether mitochondrial dysfunction regulated HMGB1 release in asthma remains unknown. The aim of this study was to explore whether phosphoglycerate mutase family member 5 (PGAM5), a mitochondrial protein, can regulate HMGB1 release in TDI-induced asthma. The gene expression data series (GSE) 67472 from gene expression omnibus (GEO) database was analyzed to compare the levels of PGAM5 in airway epithelial cells from asthma patients and healthy individuals. Male C57BL/6J mice were sensitized and challenged with TDI and treated with the PGAM5 inhibitor LFHP-1c. In vitro, human bronchial epithelial cells(16HBE) were stimulated by TDI-human serum albumin (HSA) and pretreated with PGAM5 siRNA. In this study, we observed PGAM5 expression was notably increased in airway epithelial cells of asthma patients and TDI-induced asthma mice. In vivo, inhibition of PGAM5 significantly ameliorated airway inflammation, airway hyperresponsiveness (AHR) and mucus hypersecretion, coupled with the decrease of pulmonary HMGB1 expression and release in TDI-exposed mice. In vitro, inhibition of PGAM5 improved mitochondrial dysfunction, decreased the production of reactive oxygen species (ROS) in mitochondrial. Knockdown of PGAM5 reduced the release of cytochrome C (cyt c) and HMGB1 release in TDI-induced asthma. Mechanistically, PGAM5 in bronchial epithelial cells treated by TDI-HSA significantly increased the dephosphorylation of Bax at the S184 residue, promoted the translocation of Bax to mitochondria, and contributed to the activation of mitochondrial-dependent apoptosis in TDI-induced asthma. Based on these findings, we uncovered a novel regulatory mechanism by which high PGAM5 expression promotes airway inflammation by mediating HMGB1 release in TDI-induced asthma, identifying the therapeutic effects of targeting PGAM5 in steroid-insensitive asthma model.

Mitochondrial DNA leakage: underlying mechanisms and therapeutic implications in neurological disorders

Mitochondrial dysfunction is a pivotal instigator of neuroinflammation, with mitochondrial DNA (mtDNA) leakage as a critical intermediary. This review delineates the intricate pathways leading to mtDNA release, which include membrane permeabilization, vesicular trafficking, disruption of homeostatic regulation, and abnormalities in mitochondrial dynamics. The escaped mtDNA activates cytosolic DNA sensors, especially cyclic gmp-amp synthase (cGAS) signalling and inflammasome, initiating neuroinflammatory cascades via pathways, exacerbating a spectrum of neurological pathologies. The therapeutic promise of targeting mtDNA leakage is discussed in detail, underscoring the necessity for a multifaceted strategy that encompasses the preservation of mtDNA homeostasis, prevention of membrane leakage, reestablishment of mitochondrial dynamics, and inhibition the activation of cytosolic DNA sensors. Advancing our understanding of the complex interplay between mtDNA leakage and neuroinflammation is imperative for developing precision therapeutic interventions for neurological disorders.

Neuronal Injury after Ischemic Stroke: Mechanisms of Crosstalk Involving Necroptosis

Ischemic stroke is a leading cause of disability and death worldwide, largely due to its increasing incidence associated with an aging population. This condition results from arterial obstruction, significantly affecting patients' quality of life and imposing a substantial economic burden on healthcare systems. While current treatments primarily focus on the rapid restoration of blood flow through thrombolytic therapy or surgical interventions, a limited understanding of neuronal injury mechanisms hampers the development of more effective treatments.This article explores the interplay among various cell death pathways-necroptosis, apoptosis, autophagy, ferroptosis, and pyroptosis-in the context of ischemic stroke to identify novel therapeutic targets. Each mode of cell death displays unique characteristics and roles post-stroke, and the activation of these pathways may vary across different animal models, complicating the translation of therapeutic strategies to clinical settings. Notably, the interaction between apoptosis and necroptosis is highlighted; inhibiting apoptosis might heighten the risk of necroptosis. Therefore, a balanced regulation of these pathways could promote enhanced neuronal survival.Additionally, we introduce PANoptosis, a form of cell death that encompasses pyroptosis, apoptosis, and necroptosis, emphasizing the complexity and potential therapeutic implications of these interactions. In summary, understanding the relationships among these cell death mechanisms in ischemic stroke is vital for developing new neuroprotective agents. Future research should aim for combinatorial interventions targeting multiple pathways to optimize treatment strategies and improve patient outcomes.

The dual role of PGAM5 in inflammation

In recent years, the focus on human inflammation in research has increased, with aging-related inflammation widely recognized as a defining characteristic of aging. Inflammation is strongly correlated with mitochondrial dysfunction. Phosphoglycerate mutase family member 5 (PGAM5) is a novel modulator of mitochondrial homeostasis in response to mechanical stimulation. Here we review the structure and sublocalization of PGAM5, introduce its importance in programmed cell death and summarize its crucial roles in the development and progression of inflammatory diseases such as pneumonia, hepatitis, neuroinflammation and aging. Notably, PGAM5 has dual effects on controlling inflammation: distinct PGAM5-mediated mitochondrial functions exhibit cellular heterogeneity, leading to its dual functions in inflammation control. We therefore highlight the double-edged sword nature of PGAM5 as a potential critical regulator and innovative therapeutic target in inflammation. Finally, the challenges and future directions of the use of PGAM5, which has dual properties, as a target molecule in the clinic are discussed. This review provides crucial insights to guide the development of intelligent therapeutic strategies targeting PGAM5-specific regulation to treat intractable inflammatory conditions, as well as the potential extension of its broader application to other diseases to achieve more precise and effective treatment outcomes.

Cleaving PINK1 or PGAM5? Involvement of PARL in Methamphetamine-Induced Excessive Mitophagy and Neuronal Necroptosis

BACKGROUND

Methamphetamine (Meth) is a potent psychoactive stimulant that triggers complex neurotoxicity characterized by autophagy-associated neuronal death. However, the potential mechanisms remain poorly understood. This study aimed to decipher the Meth-induced neuronal necroptosis involving mitochondrial defect-initiated excessive mitophagy caused by aberrant presenilin-associated rhomboid-like (PARL) cleavage of PTEN-induced kinase 1 (PINK1) and phosphoglycerate mutase family member 5 (PGAM5).

METHODS AND RESULTS

With the transcriptome analysis, Meth exposure significantly affected autophagy, mitophagy, and necroptosis pathways; meanwhile, the proteomic analysis revealed a marked decline in the level of PARL, which led to an imbalance in intramembrane proteolysis of PINK1 and PGAM5. In behavioral tests, Meth administration elicited pronounced cognitive decline in mice, accompanied by decreased neuronal numbers, massive autophagosomes, and mitochondrial fragmentation, and these processes can be dramatically reversed by knockin of PARL and knockdown of PGAM5 in the mouse hippocampus, molecularly manifesting as decreased necrosome formation and phosphorylated mixed lineage kinase domain-like (p-MLKL) mitochondrial membrane translocation, and improved autophagic flux.

CONCLUSION

In summary, these findings collectively underscore the key roles of the PARL-PGAM5 axis in Meth-mediated neuronal necroptosis and that targeting this axis may provide promising therapeutic strategies for mitigating Meth-induced neurotoxicity.

Research progress of small-molecule natural medicines for the treatment of ischemic stroke

Stroke is the second leading cause of disability and mortality worldwide, imposing a substantial socioeconomic burden on individuals and healthcare systems. Annually, approximately 14 million people experience stroke, with ischemic stroke comprising nearly 85% of cases, of which 10% to 20% involve large vessel occlusions. Currently, recombinant tissue plasminogen activator (tPA) remains the only approved pharmacological intervention. However, its utility is limited due to a narrow therapeutic window and low recanalization rates, making it applicable to only a minority of patients. Therefore, there is an urgent need for novel therapeutic strategies, including pharmacological advancements and combinatory treatments. Small-molecule natural medicines, particularly those derived from traditional Chinese herbs, have demonstrated significant therapeutic potential in ischemic stroke management. These compounds exert multiple neuroprotective effects, such as antioxidation, anti-inflammatory action, and inhibition of apoptosis, all of which are critical in mitigating stroke-induced cerebral damage. This review comprehensively examines the pathophysiology of acute ischemic stroke (AIS) and highlights the recent progress in the development of small-molecule natural medicines as promising therapeutic agents for cerebral ischemic stroke.

Discovery of Balasubramide Derivative with Tissue-Specific Anti-Inflammatory Activity Against Acute Lung Injury by Targeting VDAC1

Macrophage-mediated inflammatory responses including pyroptosis are involved in the pathogenesis of sepsis and acute lung injury (ALI), for which there are currently no effective therapeutic treatments. The natural product (+)-Balasubramide is an eight-membered lactam compound extracted from the leaves of the Sri Lanka plant Clausena Indica and has shown anti-inflammatory activities, but its poor pharmacokinetic properties limit its further application for ALI. In this study, a compound (+)3C-20 is discovered with improved both pharmacokinetic properties and anti-inflammatory activity from a series of (+)-Balasubramide derivatives. The compound (+)3C-20 exhibits a markedly enhanced inhibitory effect against LPS-induced expressions of pro-inflammatory factors in mouse macrophages and human PBMCs from ALI patients and shows a preferable lung tissue distribution in mice. (+)3C-20 remarkably attenuates LPS-induced ALI through lung tissue-specific anti-inflammatory actions. Mechanistically, a chemical proteomics study shows that (+)3C-20 directly binds to mitochondrial VDAC1 and inhibits VDAC1 oligomerization to block mtDNA release, further preventing NLRP3 inflammasome activation. These findings identify (+)3C-20 as a novel VDAC1 inhibitor with promising therapeutic potential for ALI associated with inflammation.

Kallikrein inhibitor derived from immunoglobulin heavy chain junction region possesses anti-thromboinflammation potential

Influenza vaccination is associated with a reduced incidence of cardiovascular events, cardiovascular death, and all-cause mortality. However, the functional role of the associated immunoglobulin remains unclear. This study identified a specific influenza-related immunoglobulin heavy chain junction region sequence (Ser-Leu-Gly-Ala-Ser-Asp, SD6) that inhibited plasma kallikrein (PKa) activity to resist thromboinflammatory responses and stroke injury. PKa is considered an attractive therapeutic target for alleviating the complications of thrombophilia-induced inflammation. In vitro, SD6 prolonged plasma recalcification and activated partial thromboplastin time, with no effects on bleeding risk-related prothrombin time, indicating selective inhibition of the intrinsic coagulation pathway. Correspondingly, at doses ranging from 0.25 to 4 mg/kg, SD6 attenuated arterial and cortical venous thrombosis in FeCl3-induced and photochemically induced mice, without impacting hemorrhage risk, and further mitigated cerebral inflammatory injury in a mouse model of transient middle cerebral artery occlusion ischemic stroke. These findings suggest that SD6 may serve as a potential therapeutic agent for the treatment of thromboinflammatory conditions.

Bat-derived oligopeptide LE6 inhibits the contact-kinin pathway and harbors anti-thromboinflammation and stroke potential

Thrombosis and inflammation are primary contributors to the onset and progression of ischemic stroke. The contact-kinin pathway, initiated by plasma kallikrein (PK) and activated factor XII (FXIIa), functions bidirectionally with the coagulation and inflammation cascades, providing a novel target for therapeutic drug development in ischemic stroke. In this study, we identified a bat-derived oligopeptide from Myotis myotis (Borkhausen, 1797), designated LE6 (Leu-Ser-Glu-Glu-Pro-Glu, 702 Da), with considerable potential in stroke therapy due to its effects on the contact kinin pathway. Notably, LE6 demonstrated significant inhibitory effects on PK and FXIIa, with inhibition constants of 43.97 μmol/L and 6.37 μmol/L, respectively. In vitro analyses revealed that LE6 prolonged plasma recalcification time and activated partial thromboplastin time. In murine models, LE6 effectively inhibited carrageenan-induced mouse tail thrombosis, FeCl 3-induced carotid artery thrombosis, and photochemically induced intracerebral thrombosis. Furthermore, LE6 significantly decreased inflammation and stroke injury in transient middle cerebral artery occlusion models. Notably, the low toxicity, hemolytic activity, and bleeding risk of LE6, along with its synthetic simplicity, underscore its clinical applicability. In conclusion, as an inhibitor of FXIIa and PK, LE6 offers potential therapeutic benefits in stroke treatment by mitigating inflammation and preventing thrombus formation.

LFHP-1c improves cognitive function after TBI in mice by reducing oxidative stress through the PGAM5-NRF2-KEAP1 ternary complex

Traumatic brain injury (TBI) is a leading cause of disability and death. Thus, timely and effective secondary brain injury intervention is crucial, with potential to improve the prognosis of TBI. Oxidative stress contributes to post-traumatic secondary cognitive impairment, and the reduction of post-traumatic oxidative stress effectively enhances cognitive function. Phosphoglycerate-mutating enzyme 5 (PGAM5), a member of the phosphoglycerate transporter enzyme family, is upregulated in TBI and induces mitochondrial autophagy. This further exacerbates damage following TBI. The present study focused on the small molecule drug, LFHP-1c, which is a novel inhibitor of PGAM5. The present study used an in vivo mouse model incorporating a controlled cortical impact-induced TBI, to examine the impact of LFHP-1c on oxidative stress and cognitive function. The present study aimed to determine the impact of LFHP-1c on the PGAM5-Kelch-like ECH-associated protein 1 (KEAP1)- nuclear factor erythroid 2-related factor 2 (NRF2) ternary complex within the TBI context. Results of the present study indicated that LFHP-1c suppresses PGAM5 expression and inhibits the development of the PGAM5-KEAP1-NRF2 ternary complex, thereby promoting the release of NRF2 and KEAP1. This in turn promotes the entry of NRF2 into the nucleus following TBI, leading to increased expression of anti-oxidative stress downstream factors, such as heme oxygenase-1, glutathione peroxidase 1 and superoxide dismutase 1. In addition, LFHP-1c also released KEAP1, leading to mitochondrial Rho GTPase 2 degradation and reducing perinuclear aggregation of mitochondria in the cell, which reduced oxidative stress and ultimately improved cognitive function after TBI.

METTL3-mediated m6A modification of OTUD1 aggravates press overload induced myocardial hypertrophy by deubiquitinating PGAM5

Background: Pathological cardiac hypertrophy, a condition that contributes to heart failure, is characterized by its intricate pathogenesis. The meticulous regulation of protein function, localization, and degradation is a crucial role played by deubiquitinating enzymes in cardiac pathophysiology. This study clarifies the participation and molecular mechanism of OTUD1 (OTU Deubiquitinase 1) in pathological cardiac hypertrophy. Methods: We generated a cardiac-specific Otud1 knockout mouse line (Otud1-CKO) and adeno-associated virus serotype 9-Otud1 mice to determine the role of Otud1 in cardiac hypertrophy. Its impact on cardiomyocytes enlargement was investigated using the adenovirus. RNA immunoprecipitation was used to validate the specific m6a methyltransferase interacted with OTUD1 transcript. RNA sequencing in conjunction with immunoprecipitation-mass spectrometry analysis was employed to identify the direct targets of OTUD1. A series of depletion mutant plasmids were constructed to detect the interaction domain of OTUD1 and its targets. Results: Ang II-stimulated neonatal rat cardiac myocytes and mice hearts subjected to transverse aortic constriction (TAC) showed increased protein levels of Otud1. Cardiac hypertrophy and dysfunction were less frequent in Otud1-CKO mice during TAC treatment, while Otud1 overexpression worsened cardiac hypertrophy and remodeling. METTL3 mediated m6A modification of OTUD1 transcript promoted mRNA stability and elevated protein expression. In terms of pathogenesis, Otud1 plays a crucial role in cardiac hypertrophy by targeting Pgam5, leading to the robust activation of the Ask1-p38/JNK signal pathway to accelerate cardiac hypertrophy. Significantly, the pro-hypertrophy effects of Otud1 overexpression were largely eliminated when Ask1 knockdown. Conclusion: Our findings confirm that targeting the OTUD1-PGAM5 axis holds significant potential as a therapeutic approach for heart failure associated with pathological hypertrophy.

Histidine Phosphorylation: Protein Kinases and Phosphatases

Phosphohistidine (pHis) is a reversible protein post-translational modification (PTM) that is currently poorly understood. The P-N bond in pHis is heat and acid-sensitive, making it more challenging to study than the canonical phosphoamino acids pSer, pThr, and pTyr. As advancements in the development of tools to study pHis have been made, the roles of pHis in cells are slowly being revealed. To date, a handful of enzymes responsible for controlling this modification have been identified, including the histidine kinases NME1 and NME2, as well as the phosphohistidine phosphatases PHPT1, LHPP, and PGAM5. These tools have also identified the substrates of these enzymes, granting new insights into previously unknown regulatory mechanisms. Here, we discuss the cellular function of pHis and how it is regulated on known pHis-containing proteins, as well as cellular mechanisms that regulate the activity of the pHis kinases and phosphatases themselves. We further discuss the role of the pHis kinases and phosphatases as potential tumor promoters or suppressors. Finally, we give an overview of various tools and methods currently used to study pHis biology. Given their breadth of functions, unraveling the role of pHis in mammalian systems promises radical new insights into existing and unexplored areas of cell biology.

Microglial CMPK2 promotes neuroinflammation and brain injury after ischemic stroke

Neuroinflammation plays a significant role in ischemic injury, which can be promoted by oxidized mitochondrial DNA (Ox-mtDNA). Cytidine/uridine monophosphate kinase 2 (CMPK2) regulates mtDNA replication, but its role in neuroinflammation and ischemic injury remains unknown. Here, we report that CMPK2 expression is upregulated in monocytes/macrophages and microglia post-stroke in humans and mice, respectively. Microglia/macrophage CMPK2 knockdown using the Cre recombination-dependent adeno-associated virus suppresses the inflammatory responses in the brain, reduces infarcts, and improves neurological outcomes in ischemic CX3CR1Cre/ERT2 mice. Mechanistically, CMPK2 knockdown limits newly synthesized mtDNA and Ox-mtDNA formation and subsequently blocks NLRP3 inflammasome activation in microglia/macrophages. Nordihydroguaiaretic acid (NDGA), as a CMPK2 inhibitor, is discovered to reduce neuroinflammation and ischemic injury in mice and prevent the inflammatory responses in primary human monocytes from ischemic patients. Thus, these findings identify CMPK2 as a promising therapeutic target for ischemic stroke and other brain disorders associated with neuroinflammation.

Drugs/agents for the treatment of ischemic stroke: Advances and perspectives

Ischemic stroke (IS) poses a significant threat to global human health and life. In recent decades, we have witnessed unprecedented progresses against IS, including thrombolysis, thrombectomy, and a few medicines that can assist in reopening the blocked brain vessels or serve as standalone treatments for patients who are not eligible for thrombolysis/thrombectomy therapies. However, the narrow time windows of thrombolysis/thrombectomy, coupled with the risk of hemorrhagic transformation, as well as the lack of highly effective and safe medications, continue to present big challenges in the acute treatment and long-term recovery of IS. In the past 3 years, several excellent articles have reviewed pathophysiology of IS and therapeutic medicines for the treatment of IS based on the pathophysiology. Regretfully, there is no comprehensive overview to summarize all categories of anti-IS drugs/agents designed and synthesized based on molecular mechanisms of IS pathophysiology. From medicinal chemistry view of point, this article reviews a multitude of anti-IS drugs/agents, including small molecule compounds, natural products, peptides, and others, which have been developed based on the molecular mechanism of IS pathophysiology, such as excitotoxicity, oxidative/nitrosative stresses, cell death pathways, and neuroinflammation, and so forth. In addition, several emerging medicines and strategies, including nanomedicines, stem cell therapy and noncoding RNAs, which recently appeared for the treatment of IS, are shortly introduced. Finally, the perspectives on the associated challenges and future directions of anti-IS drugs/agents are briefly provided to move the field forward.

Mitochondrial phosphoproteomes are functionally specialized across tissues

Mitochondria are essential organelles whose dysfunction causes human pathologies that often manifest in a tissue-specific manner. Accordingly, mitochondrial fitness depends on versatile proteomes specialized to meet diverse tissue-specific requirements. Increasing evidence suggests that phosphorylation may play an important role in regulating tissue-specific mitochondrial functions and pathophysiology. Building on recent advances in mass spectrometry (MS)-based proteomics, we here quantitatively profile mitochondrial tissue proteomes along with their matching phosphoproteomes. We isolated mitochondria from mouse heart, skeletal muscle, brown adipose tissue, kidney, liver, brain, and spleen by differential centrifugation followed by separation on Percoll gradients and performed high-resolution MS analysis of the proteomes and phosphoproteomes. This in-depth map substantially quantifies known and predicted mitochondrial proteins and provides a resource of core and tissue-specific mitochondrial proteins (mitophos.de). Predicting kinase substrate associations for different mitochondrial compartments indicates tissue-specific regulation at the phosphoproteome level. Illustrating the functional value of our resource, we reproduce mitochondrial phosphorylation events on dynamin-related protein 1 responsible for its mitochondrial recruitment and fission initiation and describe phosphorylation clusters on MIGA2 linked to mitochondrial fusion.

A Novel Hybrid of Telmisartan and Borneol Ameliorates Neuroinflammation and White Matter Injury in Ischemic Stroke Through ATF3/CH25H Axis

Cerebral ischemic stroke causes substantial white matter injury, which is further aggravated by neuroinflammation mediated by microglia/astrocytes. Given the anti-neuroinflammatory action of telmisartan and the enhancing blood-brain barrier (BBB) permeability potential of resuscitation-inducing aromatic herbs, 13 hybrids (3a-m) of telmisartan (or its simplified analogues) with resuscitation-inducing aromatic agents were designed, synthesized, and biologically evaluated. Among them, the optimal compound 3a (the ester hybrid of telmisartan and (+)-borneol) potently inhibited neuroinflammation mediated by microglia/astrocytes and ameliorated ischemic stroke. Particularly, 3a significantly conferred protection for white matter integrity after cerebral ischemic stroke via decreasing abnormally dephosphorylated neurofilament protein, upregulating myelin basic protein, and attenuating oligodendrocyte damage. Further RNA-sequencing data revealed that 3a upregulated expression of transcriptional regulator ATF3 to reduce the expression of CH25H, prevented proinflammatory state of lipid-droplet-accumulating microglia/astrocytes to limit excessive inflammation, and eventually protected neighboring oligodendrocytes to prevent white matter injury. Taken with the desirable pharmacokinetics behavior and improved brain distribution, 3a may be a feasible therapeutic agent for ischemic stroke and other neurological disorders with white matter injury.

Knockdown of Smox protects the integrity of the blood-brain barrier through antioxidant effect and Nrf2 pathway activation in stroke

Once an ischemic stroke occurs, reactive oxygen species (ROS) and oxidative stress degrade the tight connections between cerebral endothelial cells resulting in their damage. The expression of antioxidant genes may be enhanced, and ROS formation may be reduced following Nrf2 activation, which is associated with protection against ischemic stroke. Overexpression of spermine oxidase (Smox) in the neocortex led to increased H2O2 production. However, how Smox impacts the regulation of the blood-brain barrier (BBB) through antioxidants has not been examined yet. We conducted experiments both in the cell level and in the transient middle cerebral artery occlusion (tMCAO) model to evaluate the effect of Smox siRNA lentivirus (si-Smox) knockdown on BBB protection against ischemic stroke. Mice treated with si-Smox showed remarkably decreased BBB breakdown and reduced endothelial inflammation following stroke. The treatment with si-Smox significantly elevated the Bcl-2 to Bax ratio and decreased the production of cleaved caspase-3 in the tMCAO model. Further investigation revealed that the neuroprotective effect was the result of the antioxidant properties of si-Smox, which reduced oxidative stress and enhanced CD31+ cells in the peri-infarct cortical areas. Of significance, si-Smox activated Nrf2 in both bEnd.3 cells and tMCAO animals, and blocking Nrf2 with brusatol diminished the protective effects of si-Smox. The study findings suggest that si-Smox exerts neuroprotective effects and promotes angiogenesis by activating the Nrf2 pathway, thus decreasing oxidative stress and apoptosis caused by tMCAO. As a result, si-Smox may hold potential as a therapeutic candidate for preserving BBB integrity while treating ischemic stroke.

Growth differentiation factor 7 pretreatment enhances the therapeutic capacity of bone marrow-derived mesenchymal stromal cells against cerebral ischemia-reperfusion injury

Bone marrow-derived mesenchymal stem cells (BMSCs) transplantation is a promising therapeutic strategy for cerebral ischemia/reperfusion (I/R) injury; however, the clinical outcome is barely satisfactory and demands further improvement. The present study aimed to investigate whether preconditioning of BMSCs by recombinant human growth differentiation factor 7 (rhGDF7) could enhance its therapeutic capacity against cerebral I/R injury. Mouse BMSCs and primary neurons were co-cultured and exposed to oxygen glucose deprivation/reperfusion (OGD/R) stimulation. To investigate the role of exosomal microRNA-369-3p (miR-369-3p), inhibitors, RNAi and the miR-369-3p antagomir were used. Meanwhile, mice were intravenously injected with rhGDF7-preconditioned BMSCs and then received cerebral I/R surgery. Markers of inflammation, oxidative stress and neural damage were evaluated. To inhibit AMP-activated protein kinase (AMPK), compound C was used in vivo and in vitro. Compared with cell-free transwell or vehicle-preconditioned BMSCs, rhGDF7-preconditioned BMSCs significantly prevented OGD/R-induced inflammation, oxidative stress and neural damage in vitro. Meanwhile, rhGDF7-preconditioned BMSCs could prevent I/R-induced cerebral inflammation and oxidative stress in vivo. Mechanistically, rhGDF7 preconditioning significantly increased exosomal miR-369-3p expression in BMSCs and then transferred exosomal miR-369-3p to primary neurons, where it bound to phosphodiesterase 4 D (Pde4d) 3'-UTR and downregulated PDE4D expression, thereby preventing I/R-induced inflammation, oxidative stress and neural damage through activating AMPK pathway. Our study identify GDF7 pretreatment as a promising adjuvant reagent to improve the therapeutic potency of BMSCs for cerebral I/R injury and ischemic stroke.

Escin avoids hemorrhagic transformation in ischemic stroke by protecting BBB through the AMPK/Cav-1/MMP-9 pathway

BACKGROUND

Hemorrhagic transformation (HT) seriously affects the clinical application of recombinant tissue plasminogen activator (rt-PA). The main strategy for combating HT is to keep the blood-brain barrier (BBB) stable. Escin is the active ingredient of Aesculus hippocastanum and a natural mixture of triterpene saponins, and may play a part in mitigation of HT.

PURPOSE

This study sought to investigate the effect of Escin in improving rt-PA-induced HT, explore possible mechanisms, and provide new ideas for the treatment of clinical HT.

STUDY DESIGN AND METHODS

In in vivo experiments, transient middle cerebral artery occlusion (tMCAO) was undertaken in 6-week-old and 12-month-old mice, and rt-PA was administered to induce HT injury. The inhibitory effect of Escin on HT and its protective effect on neurobehavior, the BBB, and cerebrovascular endothelial cells was determined. In in vitro experiments, bEnd.3 cells were injured by oxygen-glucose deprivation/reperfusion (OGD/R) and rt-PA. The protective effect of Escin was measured by the CCK8 assay, release of lactate dehydrogenase (LDH), and expression of tight junction (TJ) proteins. In mechanistic studies, the effect of Escin on the adenosine monophosphate-activated kinase / caveolin-1 / matrix metalloprotease-9 (AMPK/Cav-1/MMP-9) pathway was investigated by employing AMPK inhibitor and Cav-1 siRNA.

RESULTS

In mice suffering from ischemia, rt-PA caused HT as well as damage to the BBB and cerebrovascular endothelial cells. Escin reduced the infarct volume, cerebral hemorrhage, improved neurobehavioral deficits, and maintained BBB integrity in rt-PA-treated tMCAO mice while attenuating bEnd.3 cells damage caused by rt-PA and OGD/R injury. Under physiological and pathological conditions, Escin increased the expression of p-AMPK and Cav-1, leading to decreased expression of MMP-9, which further attenuated damage to cerebrovascular endothelial cells, and these effects were verified with AMPK inhibitor and Cav-1 siRNA.

CONCLUSION

We revealed important details of how Escin protects cerebrovascular endothelial cells from HT, these effects were associated with the AMPK/Cav-1/MMP-9 pathway. This study provides experimental foundation for the development of new drugs to mitigate rt-PA-induced HT and the discovery of new clinical application for Escin.

FDCA Attenuates Neuroinflammation and Brain Injury after Cerebral Ischemic Stroke

Ischemic stroke is a deleterious cerebrovascular disease with few therapeutic options, and its functional recovery is highly associated with the integrity of the blood-brain barrier and neuroinflammation. The Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor fasudil (F) and the pyruvate dehydrogenase kinase (PDK) inhibitor dichloroacetate (DCA) have been demonstrated to exhibit neuroprotection in a series of neurological disorders. Hence, we synthesized and biologically examined the new salt fasudil dichloroacetate (FDCA) and validated that FDCA was eligible for attenuating ischemic volume and neurological deficits in the rat transient middle cerebral artery occlusion (tMCAO) model. Additionally, FDCA exerted superior effects than fasudil and dichloroacetate alone or in combination in reducing cerebral ischemic injury. Particularly, FDCA could maintain the blood-brain barrier (BBB) integrity by inhibiting matrix metalloproteinase 9 (MMP-9) protein expression and the degradation of zonula occludens (ZO-1) and Occludin protein. Meanwhile, FDCA could mitigate the neuroinflammation induced by microglia. The in vivo and in vitro experiments further demonstrated that FDCA disrupted the phosphorylations of myosin phosphatase target subunit 1 (MYPT1), mitogen-activated protein kinase (MAPK) cascade, including p38 and c-Jun N-terminal kinase (JNK), and pyruvate dehydrogenase (PDH) and limited excessive lactic acid metabolites, resulting in inhibition of BBB disruption and neuroinflammation. In addition, FDCA potently mitigated inflammatory response in human monocytes isolated from ischemic stroke patients, which provides the possibilities of a clinical translation perspective. Overall, these findings provided a therapeutic potential for FDCA as a candidate agent for ischemic stroke and other neurological diseases associated with BBB disruption and neuroinflammation.

Repurposing of rilpivirine for preventing platelet β3 integrin-dependent thrombosis by targeting c-Src active autophosphorylation

BACKGROUND

HIV-infected individuals are known to be at higher risk for thrombotic cardiovascular disease (CVD), which may also be differentially affected by components of anti-HIV drugs. To identify the effects of a series of FDA-approved anti-HIV drugs on platelet aggregation in humans, focusing on the novel pharmacological effects of rilpivirine (RPV), a reverse transcriptase inhibitor, on platelet function both in vitro and in vivo and the mechanisms involved.

METHODS AND RESULTS

In vitro studies showed that RPV was the only anti-HIV reagent that consistently and efficiently inhibited aggregation elicited by different agonists, exocytosis, morphological extension on fibrinogen, and clot retraction. Treatment of mice with RPV significantly prevented thrombus formation in FeCl3-injured mesenteric vessels, postcava with stenosis surgery, and ADP -induced pulmonary embolism models without defects in platelet viability, tail bleeding, and coagulation activities. RPV also improved cardiac performance in mice with post-ischemic reperfusion. A mechanistic study revealed that RPV preferentially attenuated fibrinogen-stimulated Tyr773 phosphorylation of β3-integrin by inhibiting Tyr419 autophosphorylation of c-Src. Molecular docking and surface plasmon resonance analyses showed that RPV can bind directly to c-Src. Further mutational analysis showed that the Phe427 residue of c-Src is critical for RPV interaction, suggesting a novel interaction site for targeting c-Src to block β3-integrin outside-in signaling.

CONCLUSION

These results demonstrated that RPV was able to prevent the progression of thrombotic CVDs by interrupting β3-integrin-mediated outside-in signaling via inhibiting c-Src activation without hemorrhagic side effects, highlighting RPV as a promising reagent for the prevention and therapy of thrombotic CVDs.

MicroRNA-32-3p facilitates cerebral ischemia/reperfusion injury through inhibiting Cab39/AMPK

Oxidative stress is a key pathogenic factor of cerebral ischemia/reperfusion (I/R) injury. MicroRNA-32-3p (miR-32-3p) plays critical roles in regulating ischemic diseases; however, its role in oxidative stress and cerebral I/R injury remains elusive. Primary cortical neurons and rats were treated with the agomir, antagomir and matched controls of miR-32-3p, and then received oxygen glucose deprivation/reperfusion (OGD/R) or I/R stimulation. To investigate the involvement of AMP-activated protein kinase (AMPK) and calcium-binding protein 39 (Cab39), a pharmacological inhibitor and small interfering RNA were used in vivo and in vitro. Herein, we found that miR-32-3p was upregulated in OGD/R-treated neurons and I/R-injured brains, and that inhibiting miR-32-3p by the miR-32-3p antagomir dramatically alleviated oxidative stress and neural death in OGD/R-stimulated primary cortical neurons. Conversely, overexpressing miR-32-3p by the miR-32-3p agomir further aggravated OGD/R-induced neural death and oxidative damage in primary cortical neurons. Meanwhile, we observed that the miR-32-3p antagomir prevented, while the miR-32-3p agomir facilitated neural death, oxidative damage and cerebral I/R injury in vivo. Mechanistically, miR-32-3p bound to the 3'-untranslated regions of Cab39, inhibited its protein level and subsequently inactivated AMPK. Conversely, treatment with the miR-32-3p antagomir upregulated Cab39 and activated AMPK, thereby attenuating oxidative damage and cerebral I/R injury. Moreover, inhibiting AMPK or Cab39 dramatically blocked the miR-32-3p antagomir-mediated beneficial effects against cerebral I/R injury in vivo and in vitro. miR-32-3p plays critical roles in neural death and oxidative damage upon I/R stimulation, and it is a novel target to treat cerebral I/R injury.

Phosphoglycerate mutase 5 facilitates mitochondrial dysfunction and neuroinflammation in spinal tissues after spinal cord injury

Spinal cord injury (SCI) is a high incidence worldwide that causes a heavy physical and psychological burden to patients. It is urgent to further reveal the pathological mechanism and effective treatment of SCI. Mitochondrial dysfunction plays an important role in the disease progression of SCI. As a mitochondrial membrane protein, phosphoglycerate mutase 5 (PGAM5) is mainly involved in mitochondrial function and mitosis to modulate cellular physiological functions, but the roles of PGAM5 in spinal tissues remain to be unreported after SCI. The purpose of this study was to evaluate the role of PGAM5 in SCI mice and its relationship with neuroinflammation. The results showed that the mitochondrial membrane protein PGAM5 was involved in microglia activation after SCI, and PGAM5 deletion could improve mitochondrial dysfunction (including abnormal mtDNA, ATP synthases, and ATP levels, Cyt C expression, and ROS and rGSH levels) in spinal cord tissue after SCI, Arg1/iNOS mRNA level, iNOS expression, and pro-inflammatory cytokines TNF-α, IL-1β, and IL-18 levels. In vitro, H2O2 increased TNF-α, IL-1β, and IL-18 levels in BV2 cells, and PGAM5-sh and Nrf2 activators significantly reversed H2O2-induced iNOS expression and proinflammatory cytokine production. Furthermore, IP/Western blotting results revealed that PGAM5-sh treatment significantly reduced the interaction of PGAM5 with Nrf2 and enhanced the nuclear translocation of Nrf2 in BV2 cells. The data suggested that PGAM5 was involved in the cascade of oxidative stress and inflammatory response in microglia via facilitating the expression level of Nrf2 in the nucleus after SCI. It provided a reference for clarifying the pathological mechanism and therapeutic target of SCI.

The Gut-Organ-Axis Concept: Advances the Application of Gut-on-Chip Technology

The intestine is considered to be a vital digestive organ to absorb nutrients and is the largest immune organ, while numerous microorganisms coexist with the host. It is well known that the complex interactions between the gut microbiota and the host's immune system inevitably affect the function of other organs, creating an "axis" between them. During the past few years, a new technique based mainly on microfluidics and cell biology has been developed to emulate the structure, function, and microenvironment of the human gut, called the "gut-on-chip". This microfluidic chip provides insight into key aspects of gut function in health and disease, such as the gut-brain axis, gut-liver axis, gut-kidney axis, and gut-lung axis. In this review, we first describe the basic theory of the gut axis and the various composition and parameter monitoring of the gut microarray systems, as well as summarize the development and emerging advances in the gut-organ-on-chip, with a focus on the host-gut flora and nutrient metabolism, and highlight their role in pathophysiological studies. In addition, this paper discusses the challenges and prospects for the current development and further use of the gut-organ-on-chip platform.

The inhibition of PGAM5 suppresses seizures in a kainate-induced epilepsy model via mitophagy reduction

Background

Epilepsy is a common neurological disease, and excessive mitophagy is considered as one of the major triggers of epilepsy. Mitophagy is a crucial pathway affecting reactive oxygen species. Phosphoglycerate mutase 5 (PGAM5) is a protein phosphatase present in mitochondria that regulates many biological processes including mitophagy and cell death. However, the mechanism of PGAM5 in epilepsy remains unclear. The purpose of the present study was to examine whether PGAM5 affects epilepsy through PTEN-induced putative kinase 1 (PINK1)-mediated mitophagy.

Methods

After the knockdown of PGAM5 expression by the adeno-associated virus, an epilepsy model was created by kainic acid. Next, the seizure activity was recorded by local field potentials before evaluating the level of mitochondrial autophagy marker proteins. Lastly, the ultrastructure of mitochondria, neuronal damage and oxidative stress levels were further observed.

Results

A higher PGAM5 level was found in epilepsy, and its cellular localization was in neurons. The interactions between PGAM5 and PINK1 in epilepsy were further found. After the knockdown of PGAM5, the level of PINK1 and light chain 3B was decreased and the expression of the translocase of the inner mitochondrial membrane 23 and translocase of the outer mitochondrial membrane 20 were both increased. Knockdown of PGAM5 also resulted in reduced neuronal damage, decreased malondialdehyde levels, decreased reactive oxygen species production and increased superoxide dismutase activity. In addition, the duration of spontaneous seizure-like events (SLEs), the number of SLEs and the time spent in SLEs were all reduced in the epilepsy model after inhibition of PGAM5 expression.

Conclusion

Inhibition of PGAM5 expression reduces seizures via inhibiting PINK1-mediated mitophagy.

Transcription Factor Nrf2 and Mitochondria - Friends or Foes in the Regulation of Aging Rate

At the first sight, the transcription factor Nrf2 as a master regulator of cellular antioxidant systems, and mitochondria as the main source of reactive oxygen species (ROS), should play the opposite roles in determining the pace of aging. However, since the causes of aging cannot be confined to the oxidative stress, the role of Nrf2 role cannot be limited to the regulation of antioxidant systems, and moreover, the role of mitochondria is not confined to the ROS production. In this review, we discussed only one aspect of this problem, namely, the molecular mechanisms of interaction between Nrf2 and mitochondria that influence the rate of aging and the lifespan. Experimental data accumulated so far show that the Nrf2 activity positively affects both the mitochondrial dynamics and mitochondrial quality control. Nrf2 influences the mitochondrial function through various mechanisms, e.g., regulation of nuclear genome-encoded mitochondrial proteins and changes in the balance of ROS or other metabolites that affect the functioning of mitochondria. In turn, multiple regulatory proteins functionally associated with the mitochondria affect the Nrf2 activity and even form mutual regulatory loops with Nrf2. We believe that these loops enable the fine-tuning of the cellular redox balance and, possibly, of the cellular metabolism as a whole. It has been commonly accepted for a long time that all mitochondrial regulatory signals are mediated by the nuclear genome-encoded proteins, whereas the mitochondrial genome encodes only a few respiratory chain proteins and two ribosomal RNAs. Relatively recently, mtDNA-encoded signal peptides have been discovered. In this review, we discuss the data on their interactions with the nuclear regulatory systems, first of all, Nrf2, and their possible involvement in the regulation of the aging rate. The interactions between regulatory cascades that link the programs ensuring the maintenance of cellular homeostasis and cellular responses to the oxidative stress are a significant part of both aging and anti-aging programs. Therefore, understanding these interactions will be of great help in searching for the molecular targets to counteract aging-associated diseases and aging itself.

Morin offsets PTZ-induced neuronal degeneration and cognitive decrements in rats: The modulation of TNF-α/TNFR-1/RIPK1,3/MLKL/PGAM5/Drp-1, IL-6/JAK2/STAT3/GFAP and Keap-1/Nrf-2/HO-1 trajectories

Morin is a bioactive flavonoid with prominent neuroprotective potentials, however, its impact on epilepsy-provoked cognitive dysregulations has not been revealed. Hence, the present investigation aims to divulge the potential anticonvulsant/neuroprotective effects of morin in rats using a pentylenetetrazole (PTZ)-induced kindling model with an emphasis on the possible signaling trajectories involved. Kindling was induced using a sub-convulsive dose of PTZ (35 mg/kg, i.p.), once every other day for 25 days (12 injections). The expression of targeted biomarkers and molecular signals were examined in hippocampal tissues by ELISA, Western blotting, immunohistochemistry, and histopathology. Contrary to PTZ effects, administration of morin (10 mg/kg, i.p., from day 15 of PTZ injection to the end of the experiment) significantly reduced the severity of seizures coupled with a delay in kindling acquisition. It also preserved hippocampal neurons, and diminished astrogliosis to counteract cognitive deficits, exhibited by the enhanced performance in MWM and PA tests. These favorable impacts of morin were mediated via the abrogation of the PTZ-induced necroptotic changes and mitochondrial fragmentation proven by the suppression of p-RIPK-1/p-RIPK-3/p-MLKL and PGAM5/Drp-1 cues alongside the enhancement of caspase-8. Besides, morin inhibited the inflammatory cascade documented by the attenuation of the pro-convulsant receptor/cytokines TNFR-1, TNF-α, I L-1β, and IL-6 and the marked reduction of hippocampal IL-6/p-JAK2/p-STAT3/GFAP cue. In tandem, morin signified its anti-oxidant capacity by lowering the hippocampal contents of MDA, NOX-1, and Keap-1 with the restoration of the impaired Nrf-2/HO-1 pathway. Together, these versatile neuro-modulatory effects highlight the promising role of morin in the management of epilepsy.

NRF2 and Mitochondrial Function in Cancer and Cancer Stem Cells

The NRF2–KEAP1 system is a fundamental component of the cellular response that controls a great variety of transcriptional targets that are mainly involved in the regulation of redox homeostasis and multiple cytoprotective mechanisms that confer adaptation to the stress conditions. The pleiotropic response orchestrated by NRF2 is particularly relevant in the context of oncogenic activation, wherein this transcription factor acts as a key driver of tumor progression and cancer cells’ resistance to treatment. For this reason, NRF2 has emerged as a promising therapeutic target in cancer cells, stimulating extensive research aimed at the identification of natural, as well as chemical, NRF2 inhibitors. Excitingly, the influence of NRF2 on cancer cells’ biology extends far beyond its mere antioxidant function and rather encompasses a functional crosstalk with the mitochondrial network that can influence crucial aspects of mitochondrial homeostasis, including biogenesis, oxidative phosphorylation, metabolic reprogramming, and mitophagy. In the present review, we summarize the current knowledge of the reciprocal interrelation between NRF2 and mitochondria, with a focus on malignant tumors and cancer stem cells.

The neuroprotective effects of phosphoglycerate mutase 5 are mediated by decreasing oxidative stress in HT22 hippocampal cells and gerbil hippocampus

Phosphoglycerate mutase 5 (PGAM5), a glycolytic enzyme, plays an important role in cell death and regulation of mitochondrial dynamics. In this study, we investigated the effects of PGAM5 on oxidative stress in HT22 hippocampal cells and ischemic damage in the gerbil hippocampus to elucidate the role of PGAM5 in oxidative and ischemic stress. Constructs were designed with a PEP-1 expression vector to facilitate the intracellular delivery of PGAM5 proteins. We observed time- and concentration-dependent increases in the intracellular delivery of the PEP-1-PGAM5 protein, but not its control protein (PGAM5), in HT22 cells, and morphologically demonstrated the localization of the transduced protein, which was stably expressed in the cytoplasm after 12 h of PEP-1-PGAM5 treatment. PEP-1-PGAM5 treatment significantly ameliorated cell death, reactive oxygen species formation, DNA fragmentation, and the reduction of cell proliferation induced by H₂O₂ treatment in HT22 cells. In addition, PEP-1-PGAM5 was effectively delivered to the gerbil hippocampus 8 h after treatment, and ischemia-induced hyperlocomotion and neuronal death in the hippocampal CA1 region were significantly alleviated 1 and 4 days after ischemia, respectively. Ischemia-induced microglial activation was also mitigated by treatment with 1.0 mg/kg PEP-1-PGAM5. At 3 h after ischemia, PEP-1-PGAM5 treatment significantly ameliorated the increase in lipid peroxidation, as assessed by malondialdehyde and hydroperoxide levels, and decreased glutathione levels (increases in glutathione disulfide, the oxidized form of glutathione) in the hippocampus. Two days after ischemia, treatment with PEP-1-PGAM5 significantly alleviated the ischemia-induced reduction in glutathione peroxidase activity and further increased superoxide dismutase activity in the hippocampus. The neuroprotective effects of PEP-1-PGAM5 are partially mediated by a reduction in oxidative stress, such as the formation of reactive oxygen species, and increases in the activity of antioxidants such as glutathione peroxidase and superoxide dismutase.

Mitochondrial Protein PGAM5 Emerges as a New Regulator in Neurological Diseases

As mitochondrial dysfunction has increasingly been implicated in neurological diseases, much of the investigation focuses on the response of the mitochondria. It appears that mitochondria can respond to external stimuli speedy fast, in seconds. Understanding how mitochondria sense the signal and communicate with cytosolic pathways are keys to understand mitochondrial regulation in diseases or in response to trauma. It was not until recently that a novel mitochondrial protein, phosphoglycerate mutase family member 5 (PGAM5) has emerged to be a new regulator of mitochondrial homeostasis. Although controversial results reveal beneficial as well as detrimental roles of PGAM5 in cancers, these findings also suggest PGAM5 may have diverse regulation on cellular physiology. Roles of PGAM5 in neuronal tissues remain to be uncovered. This review discusses current knowledge of PGAM5 in neurological diseases and provides future perspectives.