scholarly journals Mitofusin 2 Exerts a Protective Role in Ischemia Reperfusion Injury Through Increasing Autophagy

2018 ◽  
Vol 46 (6) ◽  
pp. 2311-2324 ◽  
Author(s):  
Cheng Peng ◽  
Wei Rao ◽  
Lei Zhang ◽  
Fan Gao ◽  
Hao Hui ◽  
...  

Background/Aims: Autophagy is essential for maintaining cellular homeostasis and the survival of terminally differentiated cells as neurons. In this study, we aim to investigate whether mitofusin 2, a mitochondrial fusion protein, mediates autophagy in cerebral ischemia/reperfusion (I/R) injury. Methods: Primary cultured neurons were treated with oxygen-glucose deprivation/reperfusion to mimic cerebral I/R injury in vitro. Autophagosomes were visualized upon TEM. Autophagy-markers were then detected to monitor autophagy by western-blot and real-time PCR, and the autophagic flux was tracked with a mRFP-GFP-LC3 construct by fluorescence as well as autophagy inhibitors and agonists. The up- and downregulation of Mfn2 were through transfecting a lentivirusexpression vector respectively. And neuronal injury was detected by cell counting kit and TUNEL assay. Results: Results showed I/R increased autophagosome formation and inhibited autolysosome degradation. Furthermore, use of autophagy related agents demonstrated that I/R injury was caused by insufficient autophagy and aggravated by impaired autophagic degradation. The results also indicated that mitofusin 2 could ameliorate I/R injury through increasing autophagosome formation and promoting the fusion of autophagosomes and lysosomes. In contrast, downregulation of mitofusin 2 aggravated the I/R injury by inhibiting autophagosome formation and the fusion of autophagosomes and lysosomes. Additionly, mitofusin 2 overexpression did not lead to autolysosome accumulation induced by I/R. Conclusions: In summary, this study explicitly demonstrated that mitofusin 2 could ameliorate I/R injury mainly through promoting autophagy, which represented a potential novel strategy for neuroprotection against cerebral I/R damage.

2020 ◽  
Author(s):  
Fei Liu ◽  
Dongxue Wang ◽  
Liyun Zhu ◽  
Jingting Du ◽  
Ping Lin ◽  
...  

Abstract Background: Fibroblast growth factor 21 (FGF21) is an important neuroprotective factor in the central nervous system (CNS), and it has been reported that FGF21 can protect against cerebral ischemia during the acute phase. However, the possible effects of FGF21 on ischemic brains and the interactions between FGF21 and nonneuronal cells have not been examined. Thus, the aim of this study was to elucidate the protective effects of endogenous FGF21 in ischemic brains.Methods: In this study, in vivo ischemia/reperfusion injury mouse model established by transient middle cerebral artery occlusion (MCAO)/reperfusion and in vitro cell models of oxygen/glucose deprivation (OGD)/reoxygenation (R) were used. Western blot analysis, RT-PCR, double immunofluorescence staining, immunohistochemistry, 2,3,5-triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin (H&E) staining, neurobehavioral tests, cell counting kit-8 (CCK-8) assay and high-throughput gene sequencing were employed to explore the mechanism by which FGF21 unleash neuroprotective effort of astrocyte phenotype shifts in ischemic stroke.Results: We found that cortical FGF21 expression significantly increased after MCAO/reperfusion, peaking at 7 d. Ischemia-activated microglia were the main sources of endogenous FGF21 in brain tissue. However, FGF21 deficiency aggravated brain injury and slowed neurological functional recovery in FGF21 knockout mice. The in vitro and vivo studies revealed that FGF21 could activate astrocytes and mediate astrocytic phenotype. FGF21-activated astrocytes contributed to neuronal survival and synaptic protein upregulation after ischemia.Conclusion: Collectively, our data indicate that FGF21 plays vital roles in alleviating ischemic brain by mediating the manifestation of potentially pro-recovery astrocytic phenotypes. Therefore, modulation of FGF21 is a potential target strategy for stroke.


Human Cell ◽  
2021 ◽  
Author(s):  
Jiaying Zhu ◽  
Zhu Zhu ◽  
Yipin Ren ◽  
Yukang Dong ◽  
Yaqi Li ◽  
...  

AbstractLINGO-1 may be involved in the pathogenesis of cerebral ischemia. However, its biological function and underlying molecular mechanism in cerebral ischemia remain to be further defined. In our study, middle cerebral artery occlusion/reperfusion (MACO/R) mice model and HT22 cell oxygen–glucose deprivation/reperfusion (OGD/R) were established to simulate the pathological process of cerebral ischemia in vivo and in vitro and to detect the relevant mechanism. We found that LINGO-1 mRNA and protein were upregulated in mice and cell models. Down-regulation LINGO-1 improved the neurological symptoms and reduced pathological changes and the infarct size of the mice after MACO/R. In addition, LINGO-1 interference alleviated apoptosis and promoted cell proliferation in HT22 of OGD/R. Moreover, down-regulation of LINGO-1 proved to inhibit nuclear translocation of p-NF-κB and reduce the expression level of p-JAK2 and p-STAT3. In conclusion, our data suggest that shLINGO-1 attenuated ischemic injury by negatively regulating NF-KB and JAK2/STAT3 pathways, highlighting a novel therapeutic target for ischemic stroke.


Pharmacology ◽  
2021 ◽  
Vol 106 (3-4) ◽  
pp. 189-201
Author(s):  
Shigang Qiao ◽  
Wen-jie Zhao ◽  
Huan-qiu Li ◽  
Gui-zhen Ao ◽  
Jian-zhong An ◽  
...  

Aim: It has been reported that necrostatin-1 (Nec-1) is a specific necroptosis inhibitor that could attenuate programmed cell death induced by myocardial ischemia/reperfusion (I/R) injury. This study aimed to observe the effect and mechanism of novel Nec-1 analog (Z)-5-(3,5-dimethoxybenzyl)-2-imine-1-methylimidazolin-4-1 (DIMO) on myocardial I/R injury. Methods: Male SD rats underwent I/R injury with or without different doses of DIMO (1, 2, or 4 mg/kg) treatment. Isolated neonatal rat cardiomyocytes were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) treatment with or without DIMO (0.1, 1, 10, or 100 μM). Myocardial infarction was measured by TTC staining. Cardiomyocyte injury was assessed by lactate dehydrogenase assay (LDH) and flow cytometry. Receptor-interacting protein 1 kinase (RIP1K) and autophagic markers were detected by co-immunoprecipitation and Western blotting analysis. Molecular docking of DIMO into the ATP binding site of RIP1K was performed using GLIDE. Results: DIMO at doses of 1 or 2 mg/kg improved myocardial infarct size. However, the DIMO 4 mg/kg dose was ineffective. DIMO at the dose of 0.1 μM decreased LDH leakage and the ratio of PI-positive cells followed by OGD/R treatment. I/R or OGD/R increased RIP1K expression and in its interaction with RIP3K, as well as impaired myocardial autophagic flux evidenced by an increase in LC3-II/I ratio, upregulated P62 and Beclin-1, and activated cathepsin B and L. In contrast, DIMO treatment reduced myocardial cell death and reversed the above mentioned changes in RIP1K and autophagic flux caused by I/R and OGD/R. DIMO binds to RIP1K and inhibits RIP1K expression in a homology modeling and ligand docking. Conclusion: DIMO exerts cardioprotection against I/R- or OGD/R-induced injury, and its mechanisms may be associated with the reduction in RIP1K activation and restoration impaired autophagic flux.


2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Sergiy M Nadtochiy ◽  
Paul S Brookes

Introduction: The adult heart utilizes mostly fat for energy production, with adaptation to different fuels (“metabolic plasticity”) being a hallmark of the healthy heart. However, metabolic maladaptation is known to occur in heart failure. As such, the ability of the heart to metabolize specific substrates could impact the outcome of pathological insults, such as ischemia-reperfusion (IR) injury. The aim of this study was to develop a system whereby adult mouse cardiomyocytes (AMC) subjected to IR injury could be supplied with different fuels, and metabolism measured in real-time. Methods: AMC were divided in 3 groups, supplied either with glucose (GLU, 5mM), palmitate/fat free BSA (FAT, 100µM) or GLU+FAT. A previously developed method for in-vitro IR injury using a Seahorse XF24 [1], was adopted for ACM. IR comprised 60 min. ischemia and 60 min. reperfusion, and additional metabolic parameters were measured separately using mitochondrial inhibitors and uncouplers [2]. Oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) were simultaneously measured during the IR protocol, followed by a cell death assay. Results: FAT cells showed higher baseline OCR and lower ECAR rates compare to GLU cells, although uncoupled OCR was lower in FAT group, suggesting a lower metabolic reserve capacity for cells respiring on fat. Upon IR, the drop in pH was significantly greater in GLU compare to FAT, indicating faster lactate production. During reperfusion, both OCR and ECAR recovered to pre-ischemic levels in GLU cells but failed to do so in FAT cells. Post-IR cell death was significantly higher in FAT vs. GLU. Surprisingly, GLU+FAT (modeling a “physiologic” substrate mix) replicated the same metabolic profile and cell death as GLU. Conclusions: (i) AMC had better recovery from IR injury using glucose as fuel. (ii) Lower cell viability in FAT (vs. GLU) correlated with smaller metabolic reserve capacity and with a smaller pH drop during ischemia. This is consistent with a known protective role for acidification during IR injury. (iii) Mixed substrates (GLU+FAT) gave a similar response to glucose alone, suggesting that fat may not be toxic, rather glucose is protective, in IR injury. [1] Circ Res. (2012), 110. 948-57. [2] J Vis Exp. (2010), 46. pii: 2511.


2018 ◽  
Vol 50 (2) ◽  
pp. 783-797 ◽  
Author(s):  
Xianzhang Zeng ◽  
Hongliang Ren ◽  
Yana Zhu ◽  
Ruru Zhang ◽  
Xinxin Xue ◽  
...  

Background/Aims: Peri-operative cerebral ischemia reperfusion injury is one of the most serious peri-operative complications that can be aggravated in patients with diabetes. A previous study showed that microglia NOX2 (a NADPH oxidase enzyme) may play an important role in this process. Here, we investigated whether increased microglial derived gp91phox, also known as NOX2, reduced oxygen glucose deprivation (OGD) after induction of hyperglycemia (HG). Methods: A rat neuronal-microglial in vitro co-culture model was used to determine the effects of gp91phox knockdown on OGD after HG using six treatment groups: A rat microglia and neuron co-culture model was established and divided into the following six groups: high glucose + scrambled siRNA transfection (HG, n = 5); HG + gp91phoxsiRNA transfection (HG-gp91siRNA, n = 5); oxygen glucose deprivation + scrambled siRNA transfection (OGD, n = 5); OGD + gp91phoxsiRNA transfection (OGD-gp91siRNA, n = 5); HG + OGD + scrambled siRNA transfection (HG-OGD, n = 5); and HG + OGD + gp91phoxsiRNA transfection (HG-OGD-gp91siRNA, n = 5). The neuronal survival rate was measured by the MTT assay, while western blotting was used to determine gp91phox expression. Microglial derived ROS and neuronal apoptosis rates were analyzed by flow cytometry. Finally, the secretion of cytokines, including IL-6, IL-8, TNF-α, and 8-iso-PGF2α was determined using an ELISA kit. Results: Neuronal survival rates were significantly decreased by HG and OGD, while knockdown of gp91phox reversed these rates. ROS production and cytokine secretion were also significantly increased by HG and OGD but were significantly inhibited by knockdown of gp91phoxsiRNA. Conclusion: Knockdown of gp91phoxsiRNA significantly reduced oxidative stress and the inflammatory response, and alleviated neuronal damage after HG and OGD treatment in a rat neuronal-microglial co-culture model.


2019 ◽  
Vol 39 (4) ◽  
Author(s):  
Mouli Tian ◽  
Mei Yang ◽  
Zhenjie Li ◽  
Yiru Wang ◽  
Wei Chen ◽  
...  

Abstract We aimed to investigate the anti-inflammatory role of fluoxetine, a selective serotonin reuptake inhibitor, in microglia (MG) and the mechanisms under oxygen glucose deprivation/reoxygenation (OGD/R). An OGD/R model on BV-2 cells was used for the study of microglia under ischemia/reperfusion injury in ischemic stroke. Lentiviral transfection was applied to knock down IκB-α. Enzyme-linked immunosorbent assay (ELISA) was used for detecting levels of TNF-α, IL-1β, and IL-6, and real-time PCR was used to assess the expression of IκB-α protein. Western blotting was applied to analyze NF-κB-signaling related proteins and Cell Counting Kit-8 (CCK-8) was used for assessing cell viability. Molecular docking and drug affinity responsive target stability (DARTS) assay were used for the detection of the interaction between IκB-α and fluoxetine. We found that fluoxetine decreased the levels of TNF-α, IL-1β, and IL-6 in supernatant as well as NF-κB subunits p65 and p50 in BV-2 cells under OGD/R. Fluoxetine significantly increased the level of IκB-α through the inhibition of IκB-α ubiquitylation and promoted the bonding of IκB-α and fluoxetine in BV-2 cells under OGD/R. Knocking down IκB-α attenuated the decreasing effect of TNF-α, IL-1β, and IL-6 as well as p65 and p50 in BV-2 cells under OGD/R led to by fluoxetine. In conclusion, our present study demonstrated the anti-inflammatory role of fluoxetine and its mechanisms related to the modulation of NF-κB-related signaling in MG under ischemia/reperfusion challenge.


2018 ◽  
Vol 314 (6) ◽  
pp. G655-G667 ◽  
Author(s):  
Zhao Lei ◽  
Meihong Deng ◽  
Zhongjie Yi ◽  
Qian Sun ◽  
Richard A. Shapiro ◽  
...  

Liver ischemia-reperfusion (I/R) injury occurs through induction of oxidative stress and release of damage-associated molecular patterns (DAMPs), including cytosolic DNA released from dysfunctional mitochondria or from the nucleus. Cyclic guanosine monophosphate–adenosine monophosphate (cGAMP) synthase (cGAS) is a cytosolic DNA sensor known to trigger stimulator of interferon genes (STING) and downstream type 1 interferon (IFN-I) pathways, which are pivotal innate immune system responses to pathogen. However, little is known about the role of cGAS/STING in liver I/R injury. We subjected C57BL/6 (WT), cGAS knockout (cGAS−/−), and STING-deficient (STINGgt/gt) mice to warm liver I/R injury and that found cGAS−/− mice had significantly increased liver injury compared with WT or STINGgt/gt mice, suggesting a protective effect of cGAS independent of STING. Liver I/R upregulated cGAS in vivo and also in vitro in hepatocytes subjected to anoxia/reoxygenation (A/R). We confirmed a previously published finding that hepatocytes do not express STING under normoxic conditions or after A/R. Hepatocytes and liver from cGAS−/− mice had increased cell death and reduced induction of autophagy under hypoxic conditions as well as increased apoptosis. Protection could be restored in cGAS−/− hepatocytes by overexpression of cGAS or by pretreatment of mice with autophagy inducer rapamycin. Our findings indicate a novel protective role for cGAS in the regulation of autophagy during liver I/R injury that occurs independently of STING. NEW & NOTEWORTHY Our studies are the first to document the important role of cGAS in the acute setting of sterile injury induced by I/R. Specifically, we provide evidence that cGAS protects liver from I/R injury in a STING-independent manner.


2020 ◽  
Author(s):  
Yi Duan ◽  
Zhifeng Gao ◽  
Xiaoyu Wang ◽  
Yuanyuan Meng ◽  
Huan Zhang

Abstract Background: Maintenance of the function and survival of liver sinusoidal endothelial cells (LSECs) play a crucial role in hepatic ischemia/reperfusion (I/R) injury, a major cause of liver impairment during surgical treatment. Emerging evidence indicate a critical role of microRNAs in I/R injury. This study aims to investigate whether miR-9-5p exert a protective effect on LSECs in vitro .Methods: We transfected LSECs with miR-9-5p mimic or mimic NC. LSECs were treated with oxygen and glucose deprivation (OGD, 5% CO2 and 95% N2), followed by glucose-free DMEM medium for 6 h, and high-glucose (HG, 30 mmol/L glucose) DMEM medium for 12 h. The biological role of miR-9-5p in I/R-induced LSEC injury was determined. Results: In the in vitro model of OGD/HG injury in LSECs, the expression levels of miR-9-5p were significantly downregulated and those of CXC chemokine receptor-4 (CXCR4) upregulated. LSEC I/R injury led to deteriorated cell death, enhanced oxidative stress and excessive inflammatory response. Mechanistically, we showed that miR-9-5p overexpression significantly upregulated both mRNA and protein levels of CXCR4, followed by rescue of LSECs, ameliorated inflammatory response, and deactivation of pro-apoptotic signaling pathways.Conclusion: miR-9-5p promotes LSEC survival and inhibits apoptosis and inflammatory response in LSECs following OGD/HG injury via downregulation of CXCR4.


2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Feng Zhou ◽  
Yu-Kai Wang ◽  
Cheng-Guo Zhang ◽  
Bing-Yi Wu

Abstract Background Stroke affects 3–4% of adults and kills numerous people each year. Recovering blood flow with minimal reperfusion-induced injury is crucial. However, the mechanisms underlying reperfusion-induced injury, particularly inflammation, are not well understood. Here, we investigated the function of miR-19a/b-3p/SIRT1/FoxO3/SPHK1 axis in ischemia/reperfusion (I/R). Methods MCAO (middle cerebral artery occlusion) reperfusion rat model was used as the in vivo model of I/R. Cultured neuronal cells subjected to OGD/R (oxygen glucose deprivation/reperfusion) were used as the in vitro model of I/R. MTT assay was used to assess cell viability and TUNEL staining was used to measure cell apoptosis. H&E staining was employed to examine cell morphology. qRT-PCR and western blot were performed to determine levels of miR-19a/b-3p, SIRT1, FoxO3, SPHK1, NF-κB p65, and cytokines like TNF-α, IL-6, and IL-1β. EMSA and ChIP were performed to validate the interaction of FoxO3 with SPHK1 promoter. Dual luciferase assay and RIP were used to verify the binding of miR-19a/b-3p with SIRT1 mRNA. Results miR-19a/b-3p, FoxO3, SPHK1, NF-κB p65, and cytokines were elevated while SIRT1 was reduced in brain tissues following MCAO/reperfusion or in cells upon OGD/R. Knockdown of SPHK1 or FoxO3 suppressed I/R-induced inflammation and cell death. Furthermore, knockdown of FoxO3 reversed the effects of SIRT1 knockdown. Inhibition of the miR-19a/b-3p suppressed inflammation and this suppression was blocked by SIRT1 knockdown. FoxO3 bound SPHK1 promoter and activated its transcription. miR-19a/b-3p directly targeted SIRT1 mRNA. Conclusion miR-19a/b-3p promotes inflammatory responses during I/R via targeting SIRT1/FoxO3/SPHK1 axis.


2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Weijun Yang ◽  
Qunjun Duan ◽  
Xian Zhu ◽  
Kaiyu Tao ◽  
Aiqiang Dong

Background. The cardioprotective effect of FSTL1 has been extensively studied in recent years, but its role in myocardial ischemia/reperfusion injury (IRI) is unclear. In this study, we investigated the effect of FSTL1 pretreatment on myocardial IRI as well as the possible involvement of autophagic pathways in its effects. Methods. The effects of FSTL1 on the viability and apoptosis of rat cardiomyocytes were investigated after exposure of cardiomyocytes to hypoxia/ischemia by using the CCK-8 assay and Annexin V/PI staining. Further, western blot analysis was used to detect the effects of FSTL1 pretreatment on autophagy-associated proteins, and confocal microscopy was used to observe autophagic flux. To confirm the role of autophagy, the cells were treated with the autophagy promoter rapamycin or the autophagy inhibitor 3-methyladenine, and cell viability and apoptosis during IRI were observed. These effects were also observed after treatment with rapamycin or 3-methyladenine followed by FSTL1 administration and IRI. Results. FSTL1 pretreatment significantly increased viability and reduced apoptosis in cardiomyocytes exposed to hypoxia/ischemia conditions. Further, FSTL1 pretreatment affected the levels of the autophagy-related proteins and enhanced autophagic flux during IRI. In addition, cell viability was enhanced and apoptosis was decreased by rapamycin treatment, while these effects were reversed by 3-MA treatment. However, when the myocardial cells were pretreated with rapamycin or 3-methyladenine, there was no significant change in their viability or apoptosis with FSTL1 treatment during IRI. Conclusions. FSTL1 plays a protective role in myocardial IRI by regulating autophagy.


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