Piroctone olamine disrupts mitochondrial dynamics in glioma cells through the PI3K/AKT pathway / 南方医科大学学报

OBJECTIVE@#To investigate the growth-inhibitory and pro-apoptotic effects of piroctone olamine (PO) on glioma cells and explore the underlying mechanism.@*METHODS@#Human glioma cell lines U251 and U373 were treated with PO and the changes in cell proliferation were detected using CCK-8 assay and EdU assay. Clone formation assay and flow cytometry were used to examine the changes in clone formation ability and apoptosis of the treated cells. Mitochondrial membrane potential of the cells and morphological changes of the mitochondria were detected using JC-1 staining and a fluorescence probe, respectively. The expressions of mitochondrial fission protein DRP1 and the fusion protein OPA1 were determined with Western blotting. Transcriptome sequencing and differential gene enrichment analysis was performed, and the expression levels of PI3K, AKT and p-AKT in the treated cells were verified using Western blotting.@*RESULTS@#CCK-8 assay showed that PO significantly inhibited the proliferation of U251 and U373 cells in a time- and dose-dependent manner (P < 0.001). EdU test showed that the proliferative activity of PO-treated cells was significantly decreased, and the number of cell colonies also decreased significantly (P < 0.01). PO treatment significantly increased apoptotic rates (P < 0.01), decreased mitochondrial membrane potential and caused obvious changes in mitochondrial morphology of the cells. Pathway enrichment analysis showed that the down-regulated genes were significantly enriched in the PI3K/AKT pathway, which was verified by Western blotting showing significantly down-regulated expression levels of PI3K, AKT and p-AKT in PO-treated cells (P < 0.05).@*CONCLUSION@#PO interferes with mitochondrial fusion and fission function through the PI3K/AKT pathway, thereby inhibiting the proliferation and increasing apoptosis of glioma cells.

Berberine alleviates myocardial diastolic dysfunction by modulating Drp1-mediated mitochondrial fission and Ca2+ homeostasis in a murine model of HFpEF / 医学前沿

Heart failure with preserved ejection fraction (HFpEF) displays normal or near-normal left ventricular ejection fraction, diastolic dysfunction, cardiac hypertrophy, and poor exercise capacity. Berberine, an isoquinoline alkaloid, possesses cardiovascular benefits. Adult male mice were assigned to chow or high-fat diet with L-NAME ("two-hit" model) for 15 weeks. Diastolic function was assessed using echocardiography and noninvasive Doppler technique. Myocardial morphology, mitochondrial ultrastructure, and cardiomyocyte mechanical properties were evaluated. Proteomics analysis, autophagic flux, and intracellular Ca2+ were also assessed in chow and HFpEF mice. The results show exercise intolerance and cardiac diastolic dysfunction in "two-hit"-induced HFpEF model, in which unfavorable geometric changes such as increased cell size, interstitial fibrosis, and mitochondrial swelling occurred in the myocardium. Diastolic dysfunction was indicated by the elevated E value, mitral E/A ratio, and E/e' ratio, decreased e' value and maximal velocity of re-lengthening (-dL/dt), and prolonged re-lengthening in HFpEF mice. The effects of these processes were alleviated by berberine. Moreover, berberine ameliorated autophagic flux, alleviated Drp1 mitochondrial localization, mitochondrial Ca2+ overload and fragmentation, and promoted intracellular Ca2+ reuptake into sarcoplasmic reticulum by regulating phospholamban and SERCA2a. Finally, berberine alleviated diastolic dysfunction in "two-hit" diet-induced HFpEF model possibly because of the promotion of autophagic flux, inhibition of mitochondrial fragmentation, and cytosolic Ca2+ overload.

Research progress of optic atrophy 1-mediated mitochondrial dynamics in skeletal system diseases / 中国修复重建外科杂志

OBJECTIVE@#To review the research progress of mitochondrial dynamics mediated by optic atrophy 1 (OPA1) in skeletal system diseases.@*METHODS@#The literatures about OPA1-mediated mitochondrial dynamics in recent years were reviewed, and the bioactive ingredients and drugs for the treatment of skeletal system diseases were summarized, which provided a new idea for the treatment of osteoarthritis.@*RESULTS@#OPA1 is a key factor involved in mitochondrial dynamics and energetics and in maintaining the stability of the mitochondrial genome. Accumulating evidence indicates that OPA1-mediated mitochondrial dynamics plays an important role in the regulation of skeletal system diseases such as osteoarthritis, osteoporosis, and osteosarcoma.@*CONCLUSION@#OPA1-mediated mitochondrial dynamics provides an important theoretical basis for the prevention and treatment of skeletal system diseases.

Mechanism of tonifying Qi by traditional Chinese medicine from mitochondrial dynamics / 中国中药杂志

According to the traditional Chinese medicine(TCM) theory, Qi is the essential component maintaining life. Mitochondria are the cellular organelles that generate energy. Qi exhibits abundant common characteristics in bioenergetics compared with mitochondria which control the cellular energy through fusion and fission. Studies have proven that the qi-tonifying function of Chinese medicinal plants and their components facilitates mitochondrial fusion, therefore enhancing ATP synthesis. These studies provide a framework for deciphering the pharmacological mechanisms of Qi-tonifying herbs. This article introduces the common source and function shared by Qi and mitochondria and the regulatory effects of herbal remedies on energy from mitochondria dynamics. This review aims to interpret the connotation of tonifying qi in TCM theory based on the modern biomedical theory.

Knock-down of ROCK2 gene improves cognitive function and reduces neuronal apoptosis in AD mice by promoting mitochondrial fusion and inhibiting its division / 细胞与分子免疫学杂志

Objective To explore the effect of knocking down Rho-associated coiled-coil kinase (ROCK2) gene on the cognitive function of amyloid precursor protein/presenilin-1 (APP/PS1) double transgenic mice and its mechanism. Methods APP/PS1 double transgenic mice were randomly divided into AD model group (AD group), ROCK2 gene knock-down group (shROCK2 group), ROCK2 gene knock-down control group (shNCgroup), and wild-type C57BL/6 mice of the same age served as the wild-type control (WT group). Morris water maze and Y maze were employed to test the cognitive function of mice. Neuron morphology was detected by Nissl staining. Immunofluorescence histochemical staining was used to detect the expression of phosphorylated dynamin-related protein 1 (p-Drp1) and mitochondrial fusion 1 (Mfn1). Western blot analysis was used to detect the expression ROCK2, cleaved-caspase-3 (c-caspase-3), B-cell lymphoma 2 (Bcl2), Bcl2-related protein X (BAX), p-Drp1, mitochondrial fission 1 (Fis1), optic atrophy 1 (OPA1), Mfn1 and Mfn2. Results Compared with AD group mice, the expression of ROCK2 in shROCK2 group mice was significantly reduced; the cognitive function was significantly improved with the number of neurons in the hippocampal CA3 and DG areas increasing, and nissl bodies were deeply stained; the expression of c-caspase-3 and BAX was decreased, while the expression of Bcl2 was increased; the expression of mitochondrial division related proteins p-Drp1 and Fis1 were decreased, while the expression of mitochondrial fusion-related proteins OPA1, Mfn1 and Mfn2 were increased. Conclusion Knock-down of ROCK2 gene can significantly improve the cognitive function and inhibit the apoptosis of nerve cells of APP/PS1 mice. The mechanism may be related to promoting mitochondrial fusion and inhibiting its division.

Effects of vibration on the expression of mitochondrial fusion and fission genes and ultrastructure of skeletal muscle in rabbits / 中华劳动卫生职业病杂志

Objective: To study the effects of vibration on the expression of mitochondrial fusion and fission genes and ultrastructure of skeletal muscle in rabbits. Methods: Thirty-two 3.5-month-old New Zealand rabbits were randomly divided into low-intensity group, medium-intensity group, high-intensity group and control group, with 8 rabbits in each group. The rabbits in the experimental group were subjected to hind limb vibration load test for 45 days. The vibration intensity of the high intensity group was 12.26 m/s(2), the medium intensity group was 6.13 m/s(2), and the low intensity group was 3.02 m/s(2) according to the effective value of weighted acceleration[a(hw (4))] for 4 hours of equal energy frequency. The control group was exposed to noise only in the same experimental environment as the medium-intensity group. The noise levels of each group were measured during the vibration load experiment. After the test, the mRNA expression of mitochondrial fusion gene (Mfn1/Mfn2) and fission gene (Fis1, Drp1) by RT-PCR in the skeletal muscles were measured and the ultrastructure of the skeletal muscles were observed in high intensity group. Results: The mRNA expression of mitochondrial in the skeletal muscle tissues of control group, low intensity group, medium intensity group and high intensity group were Mfn1: 3.25±1.36, 3.85±1.90, 4.53±2.31 and 11.63±7.68; Mfn2: 0.68±0.25, 1.02±0.40, 0.94±0.33 and 1.40±0.45; Fis1: 1.05±0.62, 1.15±0.59, 1.53±1.06 and 2.46±1.51 and Drp1: 3.72±1.76, 2.91±1.63, 3.27±2.01 and 4.21±2.46, respectively. Compared with the control group, the expressions of Mfn1 mRNA, Mfn2 mRNA and Fis1 mRNA in the high-intensity group increased significantly (P<0.05) , and the expressions of Mfn2 mRNA in the medium-intensity group and the low-intensity group increased significantly (P<0.05) . Compared with the control group, the ultrastructure of skeletal muscle of high intensity group showed mitochondrial focal accumulation, cristae membrane damage, vacuole-like changes; Z-line irregularity of muscle fibers, and deficiency of sarcomere. Conclusion: Vibration must be lead to the abnormal mitochondrial morphology and structure and the disorder of energy metabolism due to the expression imbalance of mitochondrial fusion and fission genes in skeletal muscles of rabbits, which may be an important target of vibration-induced skeletal muscle injury.

Icariin improves renal interstitial fibrosis in a rat model of chronic renal failure by regulating mitochondrial dynamics / 中国中药杂志

This study aims to explore the effect of icariin(ICA) on mitochondrial dynamics in a rat model of chronic renal failure(CRF) and to investigate the molecular mechanism of ICA against renal interstitial fibrosis(RIF). CRF was induced in male Sprague-Dawley(SD) rats with 5/6(ablation and infarction, A/I) surgery(right kidney ablation and 2/3 infarction of the left kidney). Four weeks after surgery, the model rats were randomized into the following groups: 5/6(A/I) group, 5/6(A/I)+low-dose ICA group, and 5/6(A/I)+high-dose ICA group. Another 12 rats that received sham operation were randomly classified into 2 groups: sham group and sham+ICAH group. Eight weeks after treatment, the expression of collagen-Ⅰ(Col-Ⅰ), collagen-Ⅲ(Col-Ⅲ), mitochondrial dynamics-related proteins(p-Drp1 S616, p-Drp1 S637, Mfn1, Mfn2), and mitochondrial function-related proteins(TFAM, ATP6) in the remnant kidney tissues was detected by Western blot. The expression of α-smooth muscle actin(α-SMA) was examined by immunohistochemical(IHC) staining. The NRK-52 E cells, a rat proximal renal tubular epithelial cell line, were cultured in vitro and treated with ICA of different concentration. Cell viability was detected by CCK-8 assay. In NRK-52 E cells stimulated with 20 ng·mL~(-1) TGF-β1 for 24 h, the effect of ICA on fibronectin(Fn), connective tissue growth factor(CTGF), p-Drp1 S616, p-Drp1 S637, Mfn1, Mfn2, TFAM, and ATP6 was detected by Western blot, and the ATP content and the mitochondrial morphology were determined. The 20 ng·mL~(-1) TGF-β1-stimulated NRK-52 E cells were treated with or without 5 μmol·L~(-1) ICA+10 μmol·L~(-1) mitochondrial fusion promoter M1(MFP-M1) for 24 h and the expression of fibrosis markers Fn and CTGF was detected by Western blot. Western blot result showed that the levels of Col-Ⅰ, Col-Ⅲ, and p-Drp1 S616 were increased and the levels of p-Drp1 S637, Mfn1, Mfn2, TFAM, and ATP6 were decreased in 5/6(A/I) group compared with those in the sham group. The levels of Col-Ⅰ, Col-Ⅲ, and p-Drp1 S616 were significantly lower and the levels of p-Drp1 S637, Mfn1, Mfn2, TFAM, and ATP6 were significantly higher in ICA groups than that in 5/6(A/I) group. IHC staining demonstrated that for the expression of α-SMA in the renal interstitium was higher in the 5/6(A/I) group than in the sham group and that the expression in the ICA groups was significantly lower than that in the 5/6(A/I) group. Furthermore, the improvement in the fibrosis, mitochondrial dynamics, and mitochondrial function were particularly prominent in rats receiving the high dose of ICA. The in vitro experiment revealed that ICA dose-dependently inhibited the increase of Fn, CTGF, and p-Drp1 S616, increased p-Drp1 S637, Mfn1, Mfn2, TFAM, and ATP6, elevated ATP content, and improved mitochondrial morphology of NRK-52 E cells stimulated by TGF-β1. ICA combined with MFP-M1 further down-regulated the expression of Fn and CTGF in NRK-52 E cells stimulated by TGF-β1 compared with ICA alone. In conclusion, ICA attenuated RIF of CRF by improving mitochondrial dynamics.

Porphyromonas gingivalis infection promotes mitochondrial dysfunction through Drp1-dependent mitochondrial fission in endothelial cells / 国际口腔科学杂志·英文版

Porphyromonas gingivalis (P. gingivalis), a key pathogen in periodontitis, has been shown to accelerate the progression of atherosclerosis (AS). However, the definite mechanisms remain elusive. Emerging evidence supports an association between mitochondrial dysfunction and AS. In our study, the impact of P. gingivalis on mitochondrial dysfunction and the potential mechanism were investigated. The mitochondrial morphology of EA.hy926 cells infected with P. gingivalis was assessed by transmission electron microscopy, mitochondrial staining, and quantitative analysis of the mitochondrial network. Fluorescence staining and flow cytometry analysis were performed to determine mitochondrial reactive oxygen species (mtROS) and mitochondrial membrane potential (MMP) levels. Cellular ATP production was examined by a luminescence assay kit. The expression of key fusion and fission proteins was evaluated by western blot and immunofluorescence. Mdivi-1, a specific Drp1 inhibitor, was used to elucidate the role of Drp1 in mitochondrial dysfunction. Our findings showed that P. gingivalis infection induced mitochondrial fragmentation, increased the mtROS levels, and decreased the MMP and ATP concentration in vascular endothelial cells. We observed upregulation of Drp1 (Ser616) phosphorylation and translocation of Drp1 to mitochondria. Mdivi-1 blocked the mitochondrial fragmentation and dysfunction induced by P. gingivalis. Collectively, these results revealed that P. gingivalis infection promoted mitochondrial fragmentation and dysfunction, which was dependent on Drp1. Mitochondrial dysfunction may represent the mechanism by which P. gingivalis exacerbates atherosclerotic lesions.

Adiponectin Ameliorated Pancreatic Islet Injury Induced by Chronic Intermittent Hypoxia through Inhibiting the Imbalance in Mitochondrial Fusion and Division / 中国医学科学杂志(英文版)

Objective This study aimed to assess the protective value of adiponectin (APN) in pancreatic islet injury induced by chronic intermittent hypoxia (CIH). Methods Sixty rats were randomly divided into three groups: normal control (NC) group, CIH group, and CIH with APN supplement (CIH+APN) group. After 5 weeks of CIH exposure, we conducted oral glucose tolerance tests (OGTT) and insulin released test (IRT), examined and compared the adenosine triphosphate (ATP) levels, mitochondrial membrane potential (MMP) levels, reactive oxygen species (ROS) levels, enzymes gene expression levels of

Low-Temperature Extracts of Purple Blossoms of Basil (Ocimum Basilicum L) Intervened Mitochondrial Translocation Contributes Prompted Apoptosis in Human Breast Cancer Cells

BACKGROUND: The preventive and therapeutic medical utilization of this plant is an age-long practice across the globe. This study aimed to validate the impact of dark purple blossoms of basil (Ocimum basilicum L.) aqueous extract at low temperature (0 °C) mediated mitochondrial fission contributed to induced apoptosis in human breast cancer cells. METHODS: Fresh blossoms were extracted at low temperature (0 °C) using a watery solvent. Human MCF7 breast cancer cells were then treated with 3 separate fluctuated concentrations of 0, 50, 150 and 250 µg/mL for 24 and 48 h. RESULTS: The outcomes demonstrated the presence of anthocyanins, anthraquinones, tannins, reducing sugars, glycosides, proteins, amino acids, flavonoids and volatile oils and nonappearance of Terpinoids and alkaloids. Contrastingly, frail presence of steroids in basil blossoms aqueous concentrate was noted. In addition, the results from a phytochemical subjective examination of basil (Ocimum basilicum L.) blossoms aqueous extract demonstrated that most of the credited natural impacts containing more remarkable contents of antioxidants and anticancer compounds in basil blossoms aqueous extract. Moreover, the restraint of glucose take-up was alleviated mediated by a dose-dependent manner in MCF7 cells with basil (Ocimum basilicum L.) blossoms aqueous extract inducted for 24 h, resulting in mitochondrial fission. CONCLUSION: This is the first study that shows the impact of the aqueous extract of basil (Ocimum basilicum L.) blossoms was extracted at low temperature (0°C/6 h) underlined high amounts of flavonoids and phenolic compounds bearing more anticancer and antioxidant activities compared to another aqueous extract (using boiled water solvent) and alcoholic extracts.

Role of mitochondrial fusion and fission in protective effects of dexmedetomidine against cerebral ischemia/reperfusion injury in mice / 南方医科大学学报

OBJECTIVE@#To investigate the protective effects of dexmedetomidine (DEX) against cerebral ischemia/reperfusion (I/R) injury in mice and its relation with mitochondrial fusion and fission.@*METHODS@#Male ICR mice were randomly divided into sham-operated group, I/R group, I/R+DEX group and I/R+DEX+dorsomorphin group. Mouse models of cerebral I/R injury were established by modified thread occlusion of the middle cerebral artery. DEX (50 μg/kg) was injected intraperitoneally at 30 min before cerebral ischemia, which lasted for 1 h followed by reperfusion for 24 h. The neurobehavioral deficits of the mice were evaluated based on Longa's scores. The volume of cerebral infarction was detected by TTC staining. The changes in mitochondrial morphology of the brain cells were observed with transmission electron microscopy. Western blotting was performed to detect the expressions of phosphorylated AMP-activated protein kinase (p-AMPK), mitochondrial fusion protein (Mfn2) and mitochondrial fission protein (p-Drp1) in the brain tissues.@*RESULTS@#DEX pretreatment significantly reduced the neurobehavioral score and the percent volume of cerebral infarction in mice with cerebral I/R injury. Treatment with dorsomorphin (an AMPK inhibitor) in addition to DEX significantly increased the neurobehavioral score and the percent volume of cerebral infarction in the mouse models. Transmission electron microscopy showed that DEX obviously reduced mitochondrial damage caused by cerebral I/R injury and restored mitochondrial morphology of the brain cells, and such effects were abolished by dorsomorphin treatment. Western blotting showed that DEX pretreatment significantly increased the expressions of p-AMPK and Mfn2 protein and decreased the expression of p-Drp1 protein in the brain tissue of the mice, and these changes were also reversed by dorsomorphin treatment.@*CONCLUSIONS@#Preconditioning with DEX produces protective effects against cerebral I/R injury in mice possibly by activating AMPK signaling to regulate mitochondrial fusion and fission in the brain cells.

Mitochondrial Mechanisms in Diabetic Cardiomyopathy

Mitochondrial medicine is increasingly discussed as a promising therapeutic approach, given that mitochondrial defects are thought to contribute to many prevalent diseases and their complications. In individuals with diabetes mellitus (DM), defects in mitochondrial structure and function occur in many organs throughout the body, contributing both to the pathogenesis of DM and complications of DM. Diabetic cardiomyopathy (DbCM) is increasingly recognized as an underlying cause of increased heart failure in DM, and several mitochondrial mechanisms have been proposed to contribute to the development of DbCM. Well established mechanisms include myocardial energy depletion due to impaired adenosine triphosphate (ATP) synthesis and mitochondrial uncoupling, and increased mitochondrial oxidative stress. A variety of upstream mechanisms of impaired ATP regeneration and increased mitochondrial reactive oxygen species have been proposed, and recent studies now also suggest alterations in mitochondrial dynamics and autophagy, impaired mitochondrial Ca²⁺ uptake, decreased cardiac adiponectin action, increased O-GlcNAcylation, and impaired activity of sirtuins to contribute to mitochondrial defects in DbCM, among others. In the current review, we present and discuss the evidence that underlies both established and recently proposed mechanisms that are thought to contribute to mitochondrial dysfunction in DbCM.

Protective effect of edaravone on balance of mitochondrial fusion and fission in MPP-treated PC12 cells / 生理学报

The aim of this study was to investigate the effect of edaravone (Eda) on the balance of mitochondrial fusion and fission in Parkinson's disease (PD) cell model. A cell model of PD was established by treating PC12 cells with 500 μmol/L 1-methyl-4-phenylpyridinium (MPP). Thiazole blue colorimetry (MTT) was used to detect the effect of different concentrations of Eda on the survival rate of PC12 cells exposed to MPP. The mitochondrial morphology was determined by laser confocal microscope. Western blot was used to measure the protein expression levels of mitochondrial fusion- and fission-related proteins, including OPA1, MFN2, DRP1 and Fis1. The results showed that pretreatment with different concentrations of Eda antagonized MPP-induced PC12 cell damage in a dose-dependent manner. The PC12 cells treated with MPP showed mitochondrial fragmentation, up-regulated DRP1 and Fis1 protein expression levels, and down-regulated MFN2 and OPA1 protein expression levels. Eda could reverse the above changes in the MPP-treated PC12 cells, but did not affect Fis1 protein expression. These results suggest that Eda has a protective effect on the mitochondrial fusion disruption induced by MPP in PC12 cells. The mechanism may be related to the up-regulation of OPA1/MFN2 and down-regulation of DRP1.

Progress in regulation of mitochondrial dynamics and mitochondrial autophagy / 生理学报

The abnormality of mitochondrial morphology and function is closely related to the pathogenesis of many diseases. Mitochondrial fusion-fission dynamics are critical to maintain normal morphology, distribution and quantity of mitochondria, and ensure the normal activity of cells. In addition, mitochondrial autophagy (mitophagy) plays an important role in maintaining mitochondrial quality by degrading aging or damaged mitochondria. Many previous studies showed that mitochondrial dynamics and mitophagy can regulate each other to sustain mitochondrial network homeostasis. Clarifying regulatory mechanisms of mitochondrial dynamics and mitophagy is of great significance for revealing the molecular mechanism of various diseases and for the development of new drugs targeting mitochondrial dynamics proteins or mitophagy regulatory proteins. This review focuses on the role of mitochondrial dynamics and mitophagy in mitochondrial quality control, regulatory mechanism, the interplay between those two processes, and their roles in human-related diseases.

Effects of nutritional status on mitochondrial Ca2+ handling / Efeitos do estado nutricional no manejo de Ca2+ mitocondrial

Mitochondria are central players in cell metabolism, responsible for the vast majority of ATP production in most cells. Although originally thought to be passive organelles focused only in keeping cellular ATP at adequate levels, complex interplay between mitochondrial function and cell signaling has been largely recognized over the last decades. Not surprisingly, given their role, changes in nutritional status promoted by chronic interventions like caloric restriction or short-term situations like fasting in animals or nutrient deprivation in cultured cells are one of the main factors that can activate those signaling mechanisms. One particular way in which this mitochondria-cell crosstalk can occur is through mitochondrial Ca2+ handling, a process in which Ca2+ signals generated by the cell are able to translate into elevations in mitochondrial matrix [Ca2+] due to the presence of the mitochondrial Ca2+ uniporter in the organelle. While the impact of mitochondrial Ca2+ handling on cellular function has been widely studied, the conditions which can modulate the process of mitochondrial Ca2+ handling itself are still not well characterized. In this work, we sought to test the effects of different interventions linked to nutritional status on mitochondrial Ca2+ handling. We found that caloric restriction, physiological fasting and modulations of mitochondrial dynamics resulted in modulation of mitochondrial Ca2+ handling through changes in their maximal Ca2+ retention capacity or Ca2+ uptake rates. These changes were, measured by following mitochondrial Ca2+ uptake using different strategies, employing the fluorescent Ca2+ probe Ca2+ Green 5N for experiments in isolated mitochondria and permeabilized cells and the cytosolic probe Fura2-AM in intact cells. Caloric restriction resulted in higher calcium uptake and retention in liver mitochondria, protecting against pathological conditions of Ca2+ overload during ischemia/reperfusion. On the other hand, overnight and short term fasting resulted in lower mitochondrial Ca2+ retention and oxidative phosphorylation capacity in the liver. Modulating mitochondrial morpholoy in C2C12 myoblasts showed that more fragmented mitochondria were less capable of taking up Ca2+, while more fusioned mitochondria showed the opposite phenotype. This modulation in Ca2+ handling through changes in mitochondrial morphology interfered with the process of Store-Operated Ca2+ entry in the cells, showing that these modulations can have impacts in physiological contexts as well. Overall, this work both establishes novel mechanisms of modulation of mitochondrial Ca2+ handling and demonstrates their relevance both in pathology and normal cellular physiology

Mitocôndrias possuem um papel central no metabolismo das células, sendo responsáveis pela maioria da produção de ATP na maioria dos tipos celulares. Embora originalmente se pensasse nas mitocôndrias como organelas estáticas, focadas somente em manter os níveis adequados de ATP na célula, a interação entre a função mitocondrial e a sinalização celular tem sido fortemente reconhecida nas ultimas décadas. Dado este papel, não é surpreendente que mudanças no estado nutricional, tanto crônicas como na restrição calórica quanto em situações como o jejum em animais e a privação de nutrientes em cultura de células foram demonstradas como sendo um dos principais fatores que podem ativar estes mecanismos de sinalização. Uma das formas em que esta interação entre a mitocôndria e a célula ocorre é através do manejo de Ca2+ mitocondrial, um processo em que sinais de Ca2+ gerados pela célula podem resultar em aumentos na [Ca2+] na matriz mitocondrial devido à presença do uniportador de Ca2+ mitocondrial na organelaEmbora o impacto do manejo de Ca2+ mitocondrial na função da célula tenha sido amplamente estudado, a regulação do processo de manejo de Ca2+ mitocondrial em si não é bem conhecida. Neste trabalho, nós nos propusemos a testar os efeitos de diferentes intervenções ligadas ao estado nutricional no manejo de Ca2+ mitocondrial e o possível impacto destas modulações nacapacidade de retenção e na taxa de captação de Ca2+ mitochondrial. As intervenções estudadas foram a restrição calórica, jejum e mudanças na dinâmica mitocondrial, e todas elas resultando em mudanças no manejo de Ca2+ mitocondrial, que foram medidos acompanhando a captação de Ca2+ em mitocôndrias isoladas ou células permeabilizadas utilizando a sonda Ca2+ Green 5N e em células intactas utilizando a sonda de Ca2+ citosólica Fura2-AM. Enquanto a restrição calórica resultou em uma maior capacidade de retenção de Ca2+ e em maiores taxas de captação, protegendo contra as condições patológicas de desregulação de Ca2+ observadas durante a isquemia/reperfusão, o jejum curto ou pela duração da noite resultou em uma diminuição na capacidade de retenção de Ca2+ e na oxidação fosforilativa mitocondriais. As mudanças observadas modulando a dinâmica mitocôndria (feitas utilizando-se mioblastos da linhagem C2C12) revelaram que mitocôndrias mais fragmentadas são menos capazes de captar Ca2+, enquanto mitocôndrias mais fusionadas possuem o fenótipo oposto. Essas mudanças no manejo de Ca2+ mitocondrial interferem com o processo de Store-Operated Ca2+ entry nestas células, demonstrando que essas modulações da captação de Ca2+ mitocondrial também podem ser relevantes em contextos fisiológicos. Em resumo, este trabalho ajudou a estabelecer novos mecanismos de modulação do manejo de Ca2+ mitocondrial que podem ser relevantes tanto em condições patológicas quanto na fisiologia normal das células

The First Generation of iPSC Line from a Korean Alzheimer's Disease Patient Carrying APP-V715M Mutation Exhibits a Distinct Mitochondrial Dysfunction

Alzheimer's Disease (AD) is a progressive neurodegenerative disease, which is pathologically defined by the accumulation of amyloid plaques and hyper-phosphorylated tau aggregates in the brain. Mitochondrial dysfunction is also a prominent feature in AD, and the extracellular Aβ and phosphorylated tau result in the impaired mitochondrial dynamics. In this study, we generated an induced pluripotent stem cell (iPSC) line from an AD patient with amyloid precursor protein (APP) mutation (Val715Met; APP-V715M) for the first time. We demonstrated that both extracellular and intracellular levels of Aβ were dramatically increased in the APP-V715M iPSC-derived neurons. Furthermore, the APP-V715M iPSC-derived neurons exhibited high expression levels of phosphorylated tau (AT8), which was also detected in the soma and neurites by immunocytochemistry. We next investigated mitochondrial dynamics in the iPSC-derived neurons using Mito-tracker, which showed a significant decrease of anterograde and retrograde velocity in the APP-V715M iPSC-derived neurons. We also found that as the Aβ and tau pathology accumulates, fusion-related protein Mfn1 was decreased, whereas fission-related protein DRP1 was increased in the APP-V715M iPSC-derived neurons, compared with the control group. Taken together, we established the first iPSC line derived from an AD patient carrying APP-V715M mutation and showed that this iPSC-derived neurons exhibited typical AD pathological features, including a distinct mitochondrial dysfunction.

Abnormal Mitochondria in a Non-human Primate Model of MPTP-induced Parkinson's Disease: Drp1 and CDK5/p25 Signaling

Mitochondria continuously fuse and divide to maintain homeostasis. An impairment in the balance between the fusion and fission processes can trigger mitochondrial dysfunction. Accumulating evidence suggests that mitochondrial dysfunction is related to neurodegenerative diseases such as Parkinson's disease (PD), with excessive mitochondrial fission in dopaminergic neurons being one of the pathological mechanisms of PD. Here, we investigated the balance between mitochondrial fusion and fission in the substantia nigra of a non-human primate model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD. We found that MPTP induced shorter and abnormally distributed mitochondria. This phenomenon was accompanied by the activation of dynamin-related protein 1 (Drp1), a mitochondrial fission protein, through increased phosphorylation at S616. Thereafter, we assessed for activation of the components of the cyclin-dependent kinase 5 (CDK5) and extracellular signal-regulated kinase (ERK) signaling cascades, which are known regulators of Drp1(S616) phosphorylation. MPTP induced an increase in p25 and p35, which are required for CDK5 activation. Together, these findings suggest that the phosphorylation of Drp1(S616) by CDK5 is involved in mitochondrial fission in the substantia nigra of a non-human primate model of MPTP-induced PD.

Gene knockout technology and its application in the study of the relationship between mitochondrial dynamics and insulin resistance / 生物工程学报

Mitochondrial dynamics, the processes of mitochondrial fusion and fission maintain homeostasis, are precisely regulated by fusion/fission-related proteins, and play an important physiological role in mitochondrial metabolism, quality and function. The aberrant changes of these proteins can trigger mitochondrial dynamics imbalance, which cause mitochondrial dysfunctions and result various disease states. This article focuses on gene knockout technology, and reviews the role and application progress of genes encoding for fusion and fission knockout mice in insulin resistance researches, in order to lay a foundation for future studies on signal transduction mechanism of mitochondrial dynamics imbalance in insulin resistance.

Progression of Multifaceted Immune Cells in Atherosclerotic Development

Atherosclerosis is a major cause of morbidity and mortality due to cardiovascular diseases, such as coronary artery disease, stroke, and peripheral vascular disease, that are associated with thrombosis-induced organ infarction. In Westernized countries, the high prevalence of obesity-induced insulin resistance is predicted to be a major factor leading to atherosclerotic vascular disease. Both genetic and environmental factors interfere with immune responses in atherosclerosis development with chronic and non-resolving states. The most known autoimmune disease therapy is cytokine-targeted therapy, which targets tumor necrosis factor-α and interleukin (IL)-17 antagonists. Recently, a clinical trial with the anti-IL-1β antibody (canakinumab) had shown that the anti-inflammatory effects in canakinumab-treated subjects play a critical role in reducing cardiovascular disease prevalence. Recent emerging data have suggested effective therapeutics involving anti-obesity and anti-diabetic agents, as well as statin and anti-platelet drugs, for atherothrombosis prevention. It is well-known that specialized immune differentiation and activation completely depends on metabolic reprogramming mediated by mitochondrial dynamics in distinct immune cells. Therefore, there is a strong mechanistic link between metabolism and immune function mediated by mitochondrial function. In this review, we describe that cellular metabolism in immune cells is strongly interconnected with systemic metabolism in terms of diverse phenotypes and activation.

Etoposide Induces Mitochondrial Dysfunction and Cellular Senescence in Primary Cultured Rat Astrocytes

Brain aging is an inevitable process characterized by structural and functional changes and is a major risk factor for neurodegenerative diseases. Most brain aging studies are focused on neurons and less on astrocytes which are the most abundant cells in the brain known to be in charge of various functions including the maintenance of brain physical formation, ion homeostasis, and secretion of various extracellular matrix proteins. Altered mitochondrial dynamics, defective mitophagy or mitochondrial damages are causative factors of mitochondrial dysfunction, which is linked to age-related disorders. Etoposide is an anti-cancer reagent which can induce DNA stress and cellular senescence of cancer cell lines. In this study, we investigated whether etoposide induces senescence and functional alterations in cultured rat astrocytes. Senescence-associated β-galactosidase (SA-β-gal) activity was used as a cellular senescence marker. The results indicated that etoposide-treated astrocytes showed cellular senescence phenotypes including increased SA-β-gal-positive cells number, increased nuclear size and increased senescence-associated secretory phenotypes (SASP) such as IL-6. We also observed a decreased expression of cell cycle markers, including Phospho-Histone H3/Histone H3 and CDK2, and dysregulation of cellular functions based on wound-healing, neuronal protection, and phagocytosis assays. Finally, mitochondrial dysfunction was noted through the determination of mitochondrial membrane potential using tetramethylrhodamine methyl ester (TMRM) and the measurement of mitochondrial oxygen consumption rate (OCR). These data suggest that etoposide can induce cellular senescence and mitochondrial dysfunction in astrocytes which may have implications in brain aging and neurodegenerative conditions.