Low Selenium and Low Protein Exacerbate Myocardial Damage in Keshan Disease by Affecting the PINK1/Parkin-mediated Mitochondrial Autophagy Pathway

Objective Keshan disease(KD)is a myocardial mitochondrial disease closely related to insufficient selenium(Se)and protein intake.PTEN induced putative kinase 1(PINK1)/Parkin mediated mitochondrial autophagy regulates various physiological and pathological processes in the body.This study aimed to elucidate the relationship between PINK1/Parkin-regulated mitochondrial autophagy and KD-related myocardial injury.Methods A low Se and low protein animal model was established.One hundred Wistar rats were randomly divided into 5 groups(control group,low Se group,low protein group,low Se+low protein group,and corn from KD area group).The JC-1 method was used to detect the mitochondrial membrane potential(MMP).ELISA was used to detect serum creatine kinase MB(CK-MB),cardiac troponin I(cTnI),and mitochondrial-glutamicoxalacetic transaminase(M-GOT)levels.RT-PCR and Western blot analysis were used to detect the expression of PINK1,Parkin,sequestome 1(P62),and microtubule-associated proteins1A/1B light chain 3B(MAP1LC3B).Results The MMP was significantly decreased and the activity of CK-MB,cTnI,and M-GOT significantly increased in each experimental group(low Se group,low protein group,low Se+low protein group and corn from KD area group)compared with the control group(P<0.05 for all).The mRNA and protein expression levels of PINK1,Parkin and MAP1LC3B were profoundly increased,and those of P62 markedly decreased in the experimental groups compared with the control group(P<0.05 for all).Conclusion Low Se and low protein levels exacerbate myocardial damage in KD by affecting the PINK1/Parkin-mediated mitochondrial autophagy pathway.

Characterization,expression dynamics,and potential function of OPA1 for regulation of mitochondrial morphology during spermiogenesis in Phascolosoma esculenta

Mitochondria undergo morphological changes during spermatogenesis in some animals.The mechanism and role of mitochondrial morphology regulation,however,remain somewhat unclear.In this study,we analyzed the molecular characteristics,expression dynamics and subcellular localization of optic atrophy protein 1(OPA1),a mitochondrial fusion and cristae maintenance-related protein,to reveal the possible regulatory mechanisms underlying mitochondrial morphology in Phascolosoma esculenta spermiogenesis.The full-length cDNA of the P.esculenta opa1 gene(Pe-opa1)is 3743 bp in length and encodes 975 amino acids.The Pe-OPA1 protein is highly conservative and includes a transmembrane domain,a GTPase domain,two helical bundle domains,and a lipid-interacting stalk.Gene and protein expression was higher in the coelomic fluid(a site of spermatid development)of male P.esculenta and increased first and then decreased from March to December.Moreover,their expression during the breeding stage was significantly higher than during the non-breeding stage,suggesting that Pe-OPA1 is involved in P.esculenta reproduction.The Pe-OPA1 protein was more abundant in components consisting of many spermatids than in components without,indicating that Pe-OPA1 mainly plays a role in the spermatid in coelomic fluid.Moreover,Pe-OPA1 was mainly detected in the spermatid mitochondria.Immunofluorescence experiments showed that the Pe-OPA1 are constitutively expressed and co-localized with mitochondria during spermiogenesis,suggesting its involvement in P.esculenta spermiogenesis.These results provide evidence for Pe-OPA1's involvement in the regulation of mitochondrial morphology during spermiogenesis.

Multifaceted functions of Drp1 in hypoxia/ischemia- induced mitochondrial quality imbalance: from regulatory mechanism to targeted therapeutic strategy

Hypoxic-ischemic injury is a common pathological dysfunction in clinical settings.Mitochondria are sensitive organelles that are readily damaged following ischemia and hypoxia.Dynamin-related protein 1(Drp1)regulates mitochondrial quality and cellular functions via its oligomeric changes and multiple modifications,which plays a role in mediating the induction of multiple organ damage during hypoxic-ischemic injury.However,there is active controversy and gaps in knowledge regarding the modification,protein interaction,and functions of Drp1,which both hinder and promote development of Drp1 as a novel therapeutic target.Here,we summarize recent findings on the oligomeric changes,modification types,and protein interactions of Drp1 in various hypoxic-ischemic diseases,as well as the Drp1-mediated regulation of mitochondrial quality and cell functions following ischemia and hypoxia.Additionally,potential clinical translation prospects for targeting Drp1 are discussed.This review provides new ideas and targets for proactive interventions on multiple organ damage induced by various hypoxic-ischemic diseases.

Molecular Cloning and Bioinformatical Analysis of a cDNA Encoding Mitochondrial 50S Ribosomal Protein L21 from Hevea brasiliensis Muell. Arg.

[Objective] ＂Tapping panel dryness （TPD）＂, a syndrome known as tapping incision blocked partly or entirely during latex exploiting, has become the most important factor causing great losses for rubber production. Aiming to elucidate the molecular mechanism of tapping panel dryness occurrence, this study carried out molecular cloning and bioinformatical analysis of a mRPL21 cDNA sequence, a gene associated with TPD. [Method] In a preliminary study, an expressed sequence tag （EST） encoding a deduced protein homologous to mitochondrial 50S ribosomal protein L21 （mRPL21）, which showed to be down-regulated in the latex of TPD-affected rubber trees, was isolated by suppression subtractive hybridization （SSH）. After ESTs assembling and RT-PCR validation, an 853 bp cDNA sequence with an open reading frame （ORF） was cloned, which was named as HbmRPL21 under GenBank accession number of HM230670. [Result] Bioinformatical analysis suggests that HbmRPL21 encodes a deduced polypeptide of 271 amino acids with a theoretical molecular weight （Mw） of 30.52 kDa and isolectric point （pI） of 8.40, and HbmRPL21 is a mitochondrion-targeted protein with a conserved domain of Ribosomal_L21p involving translation. Homology analysis reveals high amino acid sequence identity of mRPL21 from plants, while diversity of that between plant and animal kingdom. [Conclusion] This study laid the basis for further revealing the biological functions of mRPL21 in TPD-affected rubber trees.

Mitochondrial uncoupling protein 2 expression in colon cancer and its clinical significance

AIM: To detect the expression of mitochondrial uncoupling protein 2 (UCP2) in colon cancer and analyze the relation between UCP2 expression and clinical pathological features of colon cancer.METHODS: Fifteen colon tissue samples and 15 its adjacent tissue samples were obtained from colon cancer patients during surgical interventions. UCP2 expression was detected with immunohistochemical method in 10 normal controls, 10 hyperplastic polyp patients, 20 tubular adenoma patients and 78 colon cancer patients. Patients with rectal cancer were excluded. Quantitative reverse transcription polymerase chain reaction and Western blotting were used to detect UCP2 expressions in colon cancer tissue samples and its adjacent tissue samples. Relation between UCP2 expression and clinical pathological features of colon cancer was also analyzed. RESULTS: The UCP2 mRNA expression level was fourfold higher in colon cancer tissue samples than in its adjacent tissue samples. The UCP2 protein expression level was three-fold higher in colon cancer tissue samples than in its adjacent normal tissue samples. The UCP2 was mainly expressed in cytoplasm. The UCP2 was not expressed in normal colon mucosa. Strong positive staining for UCP2 with a diffuse distribution pattern was identified throughout the mucosa in colon cancer tissue samples with a positive expression rate of 85.9%. The UCP2 expression level was higher in colon cancer tissue samples at clinical stages Ⅲ and Ⅳ than in those at stageⅠ+ Ⅱ. Univariate analysis showed that the high UCP2 expression level was significantly correlated to colon cancer metastasis (hazard ratio = 4.321, confidence interval = 0.035-0.682, P = 0.046). CONCLUSION: UCP2 is highly expressed in human colon cancer tissue and may be involved in colon cancer metastasis.

Effect of glycosides of Cistanche on the expression of mitochondrial precursor protein and keratin type Ⅱ cytoskeletal 6A in a rat model of vascular dementia

Glycosides of Cistanche（GC）is a preparation used extensively for its neuroprotective effect against neurological diseases,but its mechanisms of action remains incompletely understood.Here,we established a bilateral common carotid artery occlusion model of vascular dementia in rats and injected the model rats with a suspension of GC（10 mg/kg/day,intraperitoneally）for 14 consecutive days.Immunohistochemistry showed that GC significantly reduced p-tau and amyloid beta（Aβ）immunoreactivity in the hippocampus of the model rats.Proteomic analysis demonstrated upregulation of mitochondrial precursor protein and downregulation of keratin type II cytoskeletal6A after GC treatment compared with model rats that had received saline.Western blot assay confirmed these findings.Our results suggest that the neuroprotective effect of GC in vascular dementia occurs via the promotion of neuronal cytoskeleton regeneration.

PTEN-induced kinase 1-induced dynamin-related protein 1 Ser637 phosphorylation reduces mitochondrial fission and protects against intestinal ischemia reperfusion injury

BACKGROUND Intestinal ischemia reperfusion(I/R)occurs in various diseases,such as trauma and intestinal transplantation.Excessive reactive oxygen species(ROS)accumulation and subsequent apoptotic cell death in intestinal epithelia are important causes of I/R injury.PTEN-induced putative kinase 1(PINK1)and phosphorylation of dynamin-related protein 1(DRP1)are critical regulators of ROS and apoptosis.However,the correlation of PINK1 and DRP1 and their function in intestinal I/R injury have not been investigated.Thus,examining the PINK1/DRP1 pathway may help to identify a protective strategy and improve the patient prognosis.AIM To clarify the mechanism of the PINK1/DRP1 pathway in intestinal I/R injury.METHODS Male C57BL/6 mice were used to generate an intestinal I/R model via superior mesenteric artery occlusion followed by reperfusion.Chiu’s score was used to evaluate intestinal mucosa damage.The mitochondrial fission inhibitor mdivi-1 was administered by intraperitoneal injection.Caco-2 cells were incubated in vitro in hypoxia/reoxygenation conditions.Small interfering RNAs and overexpression plasmids were transfected to regulate PINK1 expression.The protein expression levels of PINK1,DRP1,p-DRP1 and cleaved caspase 3 were measured by Western blotting.Cell viability was evaluated using a Cell Counting Kit-8 assay and cell apoptosis was analyzed by TUNEL staining.Mitochondrial fission and ROS were tested by MitoTracker and MitoSOX respectively.RESULTS Intestinal I/R and Caco-2 cell hypoxia/reoxygenation decreased the expression of PINK1 and p-DRP1 Ser637.Pretreatment with mdivi-1 inhibited mitochondrial fission,ROS generation,and apoptosis and ameliorated cell injury in intestinal I/R.Upon PINK1 knockdown or overexpression in vitro,we found that p-DRP1 Ser637 expression and DRP1 recruitment to the mitochondria were associated with PINK1.Furthermore,we verified the physical combination of PINK1 and p-DRP1 Ser637.CONCLUSION PINK1 is correlated with mitochondrial fission and apoptosis by regulating DRP1 phosphorylation in intestinal I/R.These results suggest that the PINK1/DRP1 pathway is involved in intestinal I/R injury,and provide a new approach for prevention and treatment.

Roles of mitochondrial unfolded protein response in mammalian stem cells

The mitochondrial unfolded protein response(UPRmt)is an evolutionarily conserved adaptive mechanism for improving cell survival under mitochondrial stress.Under physiological and pathological conditions,the UPRmt is the key to maintaining intracellular homeostasis and proteostasis.Important roles of the UPRmt have been demonstrated in a variety of cell types and in cell development,metabolism,and immune processes.UPRmt dysfunction leads to a variety of pathologies,including cancer,inflammation,neurodegenerative disease,metabolic disease,and immune disease.Stem cells have a special ability to selfrenew and differentiate into a variety of somatic cells and have been shown to exist in a variety of tissues.These cells are involved in development,tissue renewal,and some disease processes.Although the roles and regulatory mechanisms of the UPRmt in somatic cells have been widely reported,the roles of the UPRmt in stem cells are not fully understood.The roles and functions of the UPRmt depend on stem cell type.Therefore,this paper summarizes the potential significance of the UPRmt in embryonic stem cells,tissue stem cells,tumor stem cells,and induced pluripotent stem cells.The purpose of this review is to provide new insights into stem cell differentiation and tumor pathogenesis.

Mitochondrial membrane protein Bcl-xL, a regulator of adult neuronal growth and synaptic plasticity: multiple functions beyond apoptosis

The B-cell lymphoma 2 （Bcl2） family of proteins participates in cell death or survival through a mitochondrial pathway. The pro-apoptotic members of the Bcl2 family such as Bim, Bid, Bax and Bak trigger cell death by contributing to the enhancement of mitochondrial outer membrane permeabil- ity to pro-apoptotic factors such as cytochrome c, with the subsequent activation of caspases. The anti-apoptotic mem- bers, such as B-cell lymphoma-extra large （Bd-xL）, block the pro-apoptotic Bcl2 members and prevent cell death. Bcl-xL is abundantly expressed during development and in mature neurons, suggesting that it plays a role in protection from death from untoward events occurring in adult life such as ischemia, inflammation or trauma. When these neurotoxic in- sults occur, Bcl-xL translocates to mitochondria and prevents activation and homo-oligomerization of pro-apoptotic family members such Bax and Bak. Numerous studies have shown pro-survival roles for Bcl-xL in adult neurons using various models; nevertheless, the role of Bcl-xL outside of the field of neuronal death, i.e., in adult neuronal growth, excitability or synaptic plasticity, has not been studied in depth.

18β-glycyrrhetinic acid regulates mitochondrial ribosomal protein L35-associated apoptosis signaling pathways to inhibit proliferation of gastric carcinoma cells

BACKGROUND Gastric carcinoma(GC)is a common gastrointestinal malignancy worldwide.Based on the cancer-related mortality,the current prevention and treatment strategies for GC still show poor clinical results.Therefore,it is important to find effective drug treatment targets.AIM To explore the mechanism by which 18β-glycyrrhetinic acid(18β-GRA)regulates mitochondrial ribosomal protein L35(MRPL35)related signal proteins to inhibit the proliferation of GC cells.METHODS Cell counting kit-8 assay was used to detect the effects of 18β-GRA on the survival rate of human normal gastric mucosal cell line GES-1 and the proliferation of GC cell lines MGC80-3 and BGC-823.The apoptosis and cell cycle were assessed by flow cytometry.Cell invasion and migration were evaluated by Transwell assay,and cell scratch test was used to detect cell migration.Furthermore,a tumor model was established by hypodermic injection of 2.5×106 BGC-823 cells at the selected positions of BALB/c nude mice to determine the effect of 18β-GRA on GC cell proliferation,and quantitative reverse transcription-polymerase chain reaction(qRT-PCR)was used to detect MRPL35 expression in the engrafted tumors in mice.We used the term tandem mass tag(TMT)labeling combined with liquid chromatography–tandem mass spectrometry to screen for differentially expressed proteins(DEPs)extracted from GC cells and control cells after 18β-GRA intervention.A detailed bioinformatics analysis of these DEPs was performed,including Gene Ontology annotation and enrichment analysis,Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis,and so on.Moreover,STRING database(https://string-db.org/)was used to predict proteinprotein interaction(PPI)relationships and Western blot was used to detect the expression of proteins of interest in GC cells.RESULTS The results indicated that 18β-GRA could inhibit the proliferation of GC cells in a dose-and timedependent manner.It could induce GC cell apoptosis and arrest the cell cycle at G0/G1 phase.The proportion of cells arrested at S phase decreased with the increase of 18-GRA dose,and the migration and invasiveness of GC cells were inhibited.The results of animal experiments showed that 18β-GRA could inhibit tumor formation in BALB/c nude mice,and qRT-PCR results showed that MRPL35 expression level was significantly reduced in the engrafted tumors in mice.Using TMT technology,609 DEPs,among which 335 were up-regulated and 274 were down-regulated,were identified in 18β-GRA intervention compared with control.We found that the intervention of 18β-GRA in GC cells involved many important biological processes and signaling pathways,such as cellular processes,biological regulation,and TP53 signaling pathway.Notably,after the drug intervention,MRPL35 expression was significantly down-regulated(P=0.000247),TP53 expression was up-regulated(P=0.02676),and BCL2L1 was down-regulated(P=0.01699).Combined with the Retrieval of Interacting Genes/Proteins database,we analyzed the relationship between MRPL35,TP53,and BCL2L1 signaling proteins,and we found that COPS5,BAX,and BAD proteins can form a PPI network with MRPL35,TP53,and BCL2L1.Western blot analysis confirmed the intervention effect of 18β-GRA on GC cells,MRPL35,TP53,and BCL2L1 showed dose-dependent up/down-regulation,and the expression of COPS5,BAX,and BAD also increased/decreased with the change of 18β-GRA concentration.CONCLUSION 18β-GRA can inhibit the proliferation of GC cells by regulating MRPL35,COPS5,TP53,BCL2L1,BAX,and BAD.

Mechanisms of microRNA-150, cyclin B1 and mitochondrial-associated protein 2 in regulating apoptosis and inhibiting invasion and migration of Huh-7 hepatocellular carcinoma cells

Objective: To explore the mechanisms of microRNA-150, cyclin B1 and mitochondrial-associated protein 2 in regulating the apoptosis and inhibiting the invasion and migration of Huh-7 cells. Methods: Huh-7 cells were divided into the control group, the negative control group (NC group) and the miR-150 overexpression group (mimic group). The miR-150 overexpressing cell line was constructed by plasmid transfection. The cell viability and apoptosis were detected by cell counting kit-8 and flow cytometry. The cell migration and invasion capacity were measured by cell wound scratch assay and Transwell. The levels of miRNA and mRNA were detected by real-time quantitative polymerase chain reaction and the relative expression levels of proteins were detected by Western blot. Results: MiR-150 significantly inhibited the cell viability of Huh-7 and promoted its apoptosis (P<0.01). After 24 h of cultivation, the mobility of the control group and the NC group were (83.54±4.66)%and (85.57±4.74)%, respectively. The mobility of the mimic group was (49.63±3.78)%, which was significantly lower than that of the control group and the NC group (P<0.01). After 24 h of cultivation, the invasive rate of the control group and the NC group were (100.56±2.87)%and (101.63±3.74)%, respectively, and the invasive rate of mimic group was (51.63±5.32)%, which was significantly lower than that of the control group and the NC group (P<0.01). The expression levels of cyclin B1 protein and mRNA in the mimic group were significantly lower than those in the control group and the NC group (P<0.01), and the level of mitochondrial-associated protein 2 in the mimic group was significantly higher than that in the control group and the NC group (P<0.01). Conclusions: MiR-150 may inhibit the proliferation, migration, invasion and apoptosis of hepatoma carcinoma cell by regulating cyclin B1 or up-regulating mitochondrial-associated protein 2 levels.

Modulation of mitochondrial bioenergetics as a therapeutic strategy in Alzheimer＇s disease

Alzheimer’s disease （AD） is an increasingly pressing worldwide public-health, social, political and economic concern. Despite significant investment in multiple traditional therapeutic strategies that have achieved success in preclinical models addressing the pathological hallmarks of the disease, these efforts have not translated into any effective disease-modifying therapies. This could be because interventions are being tested too late in the disease process. While existing therapies provide symptomatic and clinical benefit, they do not fully address the molecular abnormalities that occur in AD neurons. The pathophysiology of AD is complex; mitochondrial bioenergetic deficits and brain hypometabolism coupled with increased mitochondrial oxidative stress are antecedent and potentially play a causal role in the disease pathogenesis. Dysfunctional mitochondria accumulate from the combination of impaired mitophagy, which can also induce injurious inflammatory responses, and inadequate neuronal mitochondrial biogenesis. Altering the metabolic capacity of the brain by modulating/potentiating its mitochondrial bioenergetics may be a strategy for disease prevention and treatment. We present insights into the mechanisms of mitochondrial dysfunction in AD brain as well as an overview of emerging treatments with the potential to prevent, delay or reverse the neurodegenerative process by targeting mitochondria.

Hypoxia promotes pulmonary vascular remodeling via HIF-1α to regulate mitochondrial dynamics

Background Increasing research suggests that mitochondrial defect plays a major role in pulmonary hypertension(PH) pathogenesis. Mitochondrial dynamics and quality control have a central role in the maintenance of the cell proliferation and apoptosis balance. However, the molecular mechanism underlying of this balance is still unknown. Methods To clarify the biological effects of hypoxic air exposure and hypoxia-inducible factor-1α(HIF-1α) on pulmonary arterial smooth muscle cell(PASMC) and pulmonary arterial hypertension rats, the cells were cultured in a hypoxic chamber under oxygen concentrations. Cell viability, reactive oxygen species level, cell death, mitochondrial morphology, mitochondrial membrane potential, mitochondrial function and mitochondrial biosynthesis, as well as fission-and fusion-related proteins, were measured under hypoxic conditions. In addition, rats were maintained under hypoxic conditions, and the right ventricular systolic pressure, right ventricular hypertrophy index and right ventricular weight/body weight ratio were examined and recorded. Further, we assessed the role of HIF-1α in the development and progression of PH using HIF-1α gene knockdown using small interfering RNA transfection. Mdivi-1 treatment was performed before hypoxia to inhibit dynamin-related protein 1(Drp1). Results We found that HIF-1α expression was increased during hypoxia, which was crucial for hypoxia-induced mitochondrial dysfunction and hypoxia-stimulated PASMCs proliferation and apoptosis. We also found that targeting mitochondrial fission Drp1 by mitochondrial division inhibitor Mdivi-1 was effective in PH model rats. The results showed that mitochondrial dynamics were involved in the pulmonary vascular remodeling under hypoxia in vivo and in vitro. Furthermore, HIF-1α also modulated mitochondrial dynamics in pulmonary vascular remodeling under hypoxia through directly regulating the expression of Drp1. Conclusions In conclusion, our data suggests that abnormal mitochondrial dynamics could be a marker for the early diagnosis of PH and monitoring disease progression. Further research is needed to study the signaling pathways that govern mitochondrial fission/fusion in PH.

Transcutaneous Auricular Vagus Nerve Stimulation Ameliorates Preeclampsia-Induced Apoptosis of Placental Trophoblastic Cells Via Inhibiting the Mitochondrial Unfolded Protein Response

Preeclampsia is a serious obstetric complication.Currently,there is a lack of effective preventive approaches for this disease.Recent studies have identified transcutaneous auricular vagus nerve stimulation(taVNS)as a potential novel non-pharmaceutical therapeutic modality for preeclampsia.In this study,we investigated whether taVNS inhibits apoptosis of placental trophoblastic cells through ROS-induced UPRmt.Our results showed that taVNS promoted the release of acetylcholine(ACh).ACh decreased the expression of UPRmt by inhibiting the formation of mitochondrial ROS(mtROS),presumably through M3AChR.This reduced the release of pro-apoptotic proteins(cleaved caspase-3,NF-kB-p65,and cytochrome C)and helped preserve the morphological and functional integrity of mitochondria,thus reducing the apoptosis of placental trophoblasts,improving placental function,and relieving preeclampsia.Our study unravels the potential pathophysiological mechanism of preeclampsia.In-depth characterization of the UPRmt is essential for developing more effective therapeutic strategies for preeclampsia targeting mitochondrial function.

Rescue axonal defects by targeting mitochondrial dynamics in hereditary spastic paraplegias

Impaired axonal development and degeneration underlie debilitating neurodegenerative diseases including hereditary spastic paraplegia, a large group of inherited diseases. Hereditary spastic paraplegia is caused by retrograde degeneration of the long corticospinal tract axons, leading to progressive spasticity and weakness of leg and hip muscles. There are over 70 subtypes with various underlying pathophysiological processes, such as defective vesicular trafficking, lipid metabolism, organelle shaping, axonal transport, and mitochondrial dysfunction. Although hereditary spastic paraplegia consists of various subtypes with different pathological characteristics, defects in mitochondrial morphology and function emerge as one of the common cellular themes in hereditary spastic paraplegia. Mitochondrial morphology and function are remodeled by mitochondrial dynamics regulated by several key fission and fusion mediators. However, the role of mitochondrial dynamics in axonal defects of hereditary spastic paraplegia remains largely unknown. Recently, studies reported perturbed mitochondrial morphology in hereditary spastic paraplegia neurons. Moreover, downregulation of mitochondrial fission regulator dynamin-related protein 1, both pharmacologically and genetically, could rescue axonal outgrowth defects in hereditary spastic paraplegia neurons, providing a potential therapeutic target for treating these hereditary spastic paraplegia. This mini-review will describe the regulation of mitochondrial fission/fusion, the link between mitochondrial dynamics and axonal defects, and the recent progress on the role of mitochondrial dynamics in axonal defects of hereditary spastic paraplegia.

Aldehyde dehydrogenase 2 preserves mitochondrial morphology and attenuates hypoxia/reoxygenationinduced cardiomyocyte injury

BACKGROUND:Disturbance of mitochondrial fi ssion and fusion(termed mitochondrial dynamics)is one of the leading causes of ischemia/reperfusion(I/R)-induced myocardial injury.Previous studies showed that mitochondrial aldehyde dehydrogenase 2(ALDH2)conferred cardioprotective effect against myocardial I/R injury and suppressed I/R-induced excessive mitophagy in cardiomyocytes.However,whether ALDH2 participates in the regulation of mitochondrial dynamics during myocardial I/R injury remains unknown.METHODS:In the present study,we investigated the effect of ALDH2 on mitochondrial dynamics and the underlying mechanisms using the H9c2 cells exposed to hypoxia/reoxygenation(H/R)as an in vitro model of myocardial I/R injury.RESULTS:Cardiomyocyte apoptosis was significantly increased after oxygen-glucose deprivation and reoxygenation(OGD/R),and ALDH2 activation largely decreased the cardiomyocyte apoptosis.Additionally,we found that both ALDH2 activation and overexpression significantly inhibited the increased mitochondrial fission after OGD/R.Furthermore,we found that ALDH2 dominantly suppressed dynamin-related protein 1(Drp1)phosphorylation(Ser616)and adenosine monophosphate-activated protein kinase(AMPK)phosphorylation(Thr172)but not interfered with the expression levels of mitochondrial shaping proteins.CONCLUSIONS:We demonstrate the protective effect of ALDH2 against cardiomyocyte H/R injury with a novel mechanism on mitochondrial fission/fusion.

Mitochondrial division inhibitor 1 protects cortical neurons from excitotoxicity:a mechanistic pathway

Mitochondrial division inhibitor 1（Mdivi-1） is a selective cell-permeable inhibitor of dynamin-related protein-1（Drp1） and mitochondrial division.To investigate the effect of Mdivi-1 on cells treated with glutamate,cerebral cortex neurons isolated from neonatal rats were treated with 10 m M glutamate for 24 hours.Normal cultured cells and dimethyl sulfoxide-cultured cells were considered as controls.Apoptotic cells were detected by flow cytometry.Changes in mitochondrial morphology were examined by electron microscopy.Drp1,Bax,and casp ase-3 expression was evaluated by western blot assays and immunocytochemistry.Mitochondrial membrane potential was detected using the JC-1 probe.Twenty-four hours after 10 m M glutamate treatment,Drp1,Bax and caspase-3 expression was upregulated,Drp1 and Bax were translocated to mitochondria,mitochondrial membrane potential was decreased and the rate of apoptosis was increased.These effects were inhibited by treatment with 50 μM Mdivi-1 for 2 hours.This finding indicates that Mdivi-1 is a candidate neuroprotective drug that can potentially mitigate against neuronal injury caused by glutamate-induced excitotoxicity.

Mitochondrial Dysregulation in Skeletal Muscle from Patients Diagnosed with Alzheimer’s Disease and Sporadic Inclusion Body Myositis

Mitochondrial dysfunction is implicated in Alzheimer’s disease (AD) and disruption of mitochondrial dynamic pathways has been documented in brains from patients diagnosed with AD;although it is unclear whether other tissues are also affected. Much less is known about the mitochondria in patients diagnosed with sporadic Inclusion Body Myositis (sIBM). The current study examined mitochondrial biology in skeletal muscle from AD and sIBM patients compared to healthy, elderly individuals. Skeletal muscle samples were obtained from the National Disease Research Interchange and mRNA, protein content, and enzyme activity was used to assess mitochondrial parameters. Patients diagnosed with AD or sIBM demonstrated reduced mitofusin 2 and optic atrophy protein 1 protein. AD patients also displayed increased mRNA of superoxide dismutase 2, catalase, and uncoupling protein 3. Amyloid b precursor protein mRNA was higher in sIBM patients only compared to both AD patients and elderly individuals. Both total and phosphorylated AMPK protein content, an upstream regulator of mitochondrial dynamics and biogenesis, were also reduced in sIBM patients. The current study demonstrates a disruption in signaling pathways regulating mitochondrial dynamics in both AD and sIBM patients, although the underlying causes may differ.

基于NLRP3通路探讨线粒体自噬在PCOS卵巢组织炎症反应中的作用

目的基于NOD样受体热蛋白结构域相关蛋白3(NLRP3)通路探讨线粒体自噬在多囊卵巢综合征(PCOS)卵巢组织炎症反应中的作用。方法人卵巢颗粒细胞(GCs)系SVOG用25 nmol/L双氢睾酮(DHT)处理24 h以建立PCOS细胞模型。SVOG细胞用携带NLRP3(Ad-NLRP3)及阴性载体(Ad-EV)或NLRP3 shRNA(sh-NLRP3)及阴性对照(sh-NC)的腺病毒转染,以过表达或敲低NLRP3表达。使用Mito-Tracker染色和GFP-LC3染色评估细胞中线粒体自噬情况。分别通过TUNEL染色、JC-1染色、Mito-SOX染色分析细胞凋亡、线粒体膜电位、线粒体衍生超氧化物产生情况。32只雌性BALB/c小鼠随机分为对照(Con)组、脱氢表雄酮(DHEA)组、DHEA+sh-NC组、DHEA+sh-NLRP3组,每组8只。除Con组外,其他组用DHEA处理小鼠以建立PCOS模型。DHEA+sh-NLRP3组、DHEA+sh-NC组通过尾静脉注射浓度为1×109 TU/ml的慢病毒包装的sh-NLRP3或sh-NC。透射电子显微镜观察各组小鼠卵巢组织中线粒体的超微结构。结果与DHT+sh-NC组相比,DHT+sh-NLRP3组SVOG细胞的NLRP3水平降低(P<0.05)。DHT+sh-NLRP3组SVOG细胞中GFP-LC3和线粒体的共定位较DHT+sh-NC组增加(P<0.05)。与DHT+sh-NC组相比,DHT+sh-NLRP3组SVOG细胞的TUNEL阳性细胞的数目和Mito-SOX荧光密度降低、多聚体JC-1/单体JC-1比值增加(P<0.05)。与Con+Ad-EV组相比,Con+Ad-NLRP3组SVOG细胞的NLRP3水平、TUNEL阳性细胞数目、Mito-SOX荧光密度增加(P<0.05),GFP-LC3和线粒体的共定位以及多聚体JC-1/单体JC-1比值降低(P<0.05)。与Con组相比,DHEA组小鼠卵巢组织中TUNEL阳性细胞、相对活性氧(ROS)强度和受损线粒体百分比均显著增加(P<0.05)。与DHEA+sh-NC组相比,DHEA+sh-NLRP3组卵巢组织中TUNEL阳性细胞、相对ROS强度和受损线粒体百分比均降低(P<0.05)。结论NLRP3激活诱导的线粒体自噬活性导致线粒体功能障碍并促进GCs中线粒体相关凋亡。NLRP3敲低有利于线粒体稳态,并改善GCs对氧化应激损伤的抵抗,从而促进PCOS的恢复。

黄精多糖对β淀粉样蛋白诱导细胞损伤的保护作用及机制研究

目的探讨黄精多糖(Polygonatum sibiricum polysaccharides,PSP)对β淀粉样蛋白(25-35)[βamyloid protein(25-35),Aβ_(25-35)]诱导的SH-SY5Y细胞氧化损伤及凋亡的神经保护作用及其机制。方法通过CCK-8实验确定Aβ_(25-35)和PSP的干预浓度和时间,并将细胞分为对照组、模型组、低、中、高剂量组。检测细胞的凋亡、线粒体膜电位(mitochondrial membrane potential,MMP)水平、细胞色素C(cytochrome C,Cyt C)含量、胞内活性氧(reactive oxygen species,ROS)含量以及多种抗氧化酶活性变化。采用蛋白质印迹法(western blot,WB)实验检测Nrf2/HO-1和JAK2/STAT3信号通路相关蛋白表达。结果与模型组相比,PSP能够显著恢复细胞活力,清除胞内ROS,升高细胞MMP,减少线粒体Cyt C释放,抑制凋亡蛋白的生成。同时能够逆转Aβ_(25-35)对Nrf2/HO-1信号通路的抑制,降低JAK2/STAT3通路的磷酸化程度。结论PSP可通过上调Nrf2/HO-1信号通路相关蛋白分子的表达,逆转JAK2/STAT3信号通路的磷酸化,减轻氧化损伤,改善线粒体功能并最终抑制细胞凋亡。