scholarly journals ApoE4 (Δ272–299) induces mitochondrial‐associated membrane formation and mitochondrial impairment by enhancing GRP75-modulated mitochondrial calcium overload in neuron

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tao Liang ◽  
Weijian Hang ◽  
Jiehui Chen ◽  
Yue Wu ◽  
Bin Wen ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Er Stress ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Calcium Transport ◽  
Calcium Overload ◽  
Mitochondrial Calcium ◽  
Mitochondrial Impairment

Abstract Background Apolipoprotein E4 (apoE4) is a major genetic risk factor of Alzheimer’s disease. Its C-terminal-truncated apoE4 (Δ272–299) has neurotoxicity by affecting mitochondrial respiratory function. However, the molecular mechanism(s) underlying the action of apoE4 (Δ272–299) in mitochondrial function remain poorly understood. Methods The impact of neuronal apoE4 (Δ272–299) expression on ER stress, mitochondrial-associated membrane (MAM) formation, GRP75, calcium transport and mitochondrial impairment was determined in vivo and in vitro. Furthermore, the importance of ER stress or GRP75 activity in the apoE4 (Δ272–299)-promoted mitochondrial dysfunction in neuron was investigated. Results Neuronal apoE4 (Δ272–299) expression induced mitochondrial impairment by inducing ER stress and mitochondrial-associated membrane (MAM) formation in vivo and in vitro. Furthermore, apoE4 (Δ272–299) expression promoted GRP75 expression, mitochondrial dysfunction and calcium transport into the mitochondria in neuron, which were significantly mitigated by treatment with PBA (an inhibitor of ER stress), MKT077 (a specific GRP75 inhibitor) or GRP75 silencing. Conclusions ApoE4 (Δ272–299) significantly impaired neuron mitochondrial function by triggering ER stress, up-regulating GRP75 expression to increase MAM formation, and mitochondrial calcium overload. Our findings may provide new insights into the neurotoxicity of apoE4 (Δ272–299) against mitochondrial function and uncover new therapeutic targets for the intervention of Alzheimer’s disease.

Abstract P401: The Anti-arrhythmic Effects Of VDAC Isoforms Are Mediated By Glutamate 73 Through Regulation Of Mitochondrial Calcium Transport

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Lauren Crisman ◽  
Hirohito Shimizu ◽  
Adam Langenbacher ◽  
Jie Huang ◽  
Kevin Wang ◽  
...  
Keyword(s):  
Calcium Transport ◽  
Calcium Uptake ◽  
Calcium Overload ◽  
Mitochondrial Calcium ◽  
Cellular Processes ◽  
Excess Calcium ◽  
Evolutionarily Conserved ◽  
Mitochondrial Calcium Uptake

Mitochondria critically regulate cellular processes such as bioenergetics, metabolism, calcium homeostasis and apoptosis. VDAC proteins are abundant proteins that control the passage of ions and metabolites across the outer mitochondrial membrane. We have previously shown that activation of VDAC2, is able to buffer excess calcium and thereby suppress calcium overload induced arrhythmogenic events in vitro and in vivo. However, the mechanism by which VDAC2 regulates calcium transport and cardiac contractions remained unclear. It is also unclear whether all three VDAC isoforms (VDAC1,2 and 3) possess similar cardioprotective activity. The zebrafish tremblor/ncx1 mutant lacks functional NCX1 in cardiomyocytes leading to calcium overload, and the manifestation of fibrillation-like phenotypes. Using the tremblor/ncx1 mutant as a model, we observed isoform-specific differences between the VDAC family members. VDAC1 and VDAC2 enhanced mitochondrial calcium trafficking and restore rhythmic contraction in tremblor mutants, whereas, VDAC3 did not. We found that the differing rescue capabilities of VDAC proteins were dependent upon residues in their N-terminal halves. Phylogenetic analysis further revealed the presence of an evolutionarily conserved glutamate at position 73 (E73) within VDAC1 and VDAC2, but a glutamine (Q73) in VDAC3. Excitingly, we showed that replacing VDAC2 E73 with Q73 ablated its calcium transporting activity. Conversely, substituting the Q73 with E73 allows VDAC3 to gain calcium trafficking and cardioprotective abilities. Overall, our study demonstrates an essential role for the evolutionarily conserved glutamate-73 in determining the anti-arrhythmic effect of VDAC isoforms through their regulation of mitochondrial calcium uptake.

scholarly journals Overexpression of SERCA2a Alleviates Cardiac Microvascular Ischemic Injury by Suppressing Mfn2-Mediated ER/Mitochondrial Calcium Tethering

2021 ◽  
Vol 9 ◽  
Author(s):  
Feng Tian ◽  
Ying Zhang
Keyword(s):  
Endoplasmic Reticulum ◽  
Infarct Size ◽  
Myocardial Infarct ◽  
Ischemic Injury ◽  
Calcium Overload ◽  
Mitochondrial Calcium ◽  
Myocardial Infarct Size ◽  
Hypoxic Injury

Our previous research has shown that type-2a Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) undergoes posttranscriptional oxidative modifications in cardiac microvascular endothelial cells (CMECs) in the context of excessive cardiac oxidative injury. However, whether SERCA2a inactivity induces cytosolic Ca2+ imbalance in mitochondrial homeostasis is far from clear. Mitofusin2 (Mfn2) is well known as an important protein involved in endoplasmic reticulum (ER)/mitochondrial Ca2+ tethering and the regulation of mitochondrial quality. Therefore, the aim of our study was to elucidate the specific mechanism of SERCA2a-mediated Ca2+ overload in the mitochondria via Mfn2 tethering and the survival rate of the heart under conditions of cardiac microvascular ischemic injury. In vitro, CMECs extracted from mice were subjected to 6 h of hypoxic injury to mimic ischemic heart injury. C57-WT and Mfn2KO mice were subjected to a 1 h ischemia procedure via ligation of the left anterior descending branch to establish an in vivo cardiac ischemic injury model. TTC staining, immunohistochemistry and echocardiography were used to assess the myocardial infarct size, microvascular damage, and heart function. In vitro, ischemic injury induced irreversible oxidative modification of SERCA2a, including sulfonylation at cysteine 674 and nitration at tyrosine 294/295, and inactivation of SERCA2a, which initiated calcium overload. In addition, ischemic injury-triggered [Ca2+]c overload and subsequent [Ca2+]m overload led to mPTP opening and ΔΨm dissipation compared with the control. Furthermore, ablation of Mfn2 alleviated SERCA2a-induced mitochondrial calcium overload and subsequent mito-apoptosis in the context of CMEC hypoxic injury. In vivo, compared with that in wild-type mice, the myocardial infarct size in Mfn2KO mice was significantly decreased. In addition, the findings revealed that Mfn2KO mice had better heart contractile function, decreased myocardial infarction indicators, and improved mitochondrial morphology. Taken together, the results of our study suggested that SERCA2a-dependent [Ca2+]c overload led to mitochondrial dysfunction and activation of Mfn2-mediated [Ca2+]m overload. Overexpression of SERCA2a or ablation of Mfn2 expression mitigated mitochondrial morphological and functional damage by modifying the SERCA2a/Ca2+-Mfn2 pathway. Overall, these pathways are promising therapeutic targets for acute cardiac microvascular ischemic injury.

The Association of Neuronal Stress with Activating Transcription Factor 3 in Dorsal Root Ganglion of in vivo and in vitro Models of Bortezomib- Induced Neuropathy

2018 ◽  
Vol 19 (1) ◽  
pp. 50-64 ◽  
Author(s):  
Yiting Yin ◽  
Xin Qi ◽  
Yuan Qiao ◽  
Huaxiang Liu ◽  
Zihan Yan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Er Stress ◽  
Mitochondrial Dysfunction ◽  
Cell Apoptosis ◽  
Activating Transcription Factor 3 ◽  
Drg Neurons ◽  
Activating Transcription Factor ◽  
Intracellular Oxidative Stress

Background: The notion that proteasome inhibitor bortezomib (BTZ) induced intracellular oxidative stress resulting in peripheral neuropathy has been generally accepted. The association of mitochondrial dysfunction, cell apoptosis, and endoplasmic reticulum (ER) stress with intracellular oxidative stress is ambiguous and still needs to be investigated. The activation of activating transcription factor 3 (ATF3) is a stress-hub gene which was upregulated in dorsal root ganglion (DRG) neurons after different kinds of peripheral nerve injuries. Objective: To investigate a mechanism underlying the action of BTZ-induced intracellular oxidative stress, mitochondrial dysfunction, cell apoptosis, and ER stress via activation of ATF3. </P><P> Methods: Primary cultured DRG neurons with BTZ induced neurotoxicity and DRG from BTZ induced painful peripheral neuropathic rats were used to approach these questions. Results: BTZ administration caused the upregulation of ATF3 paralleled with intracellular oxidative stress, mitochondrial dysfunction, cell apoptosis, and ER stress in DRG neurons both in vitro and in vivo. Blocking ATF3 signaling by small interfering RNA (siRNA) gene silencing technology resulted in decreased intracellular oxidative stress, mitochondrial dysfunction, cell apoptosis, and ER stress in DRG neurons after BTZ treatment. This study exhibited important mechanistic insight into how BTZ induces neurotoxicity through the activation of ATF3 resulting in intracellular oxidative stress, mitochondrial dysfunction, cell apoptosis, and ER stress and provided a novel potential therapeutic target by blocking ATF3 signaling.

To rectify Alzheimer's disease etiology, excessive mitochondrial division might be stopped or mitophagy might be promoted

2021 ◽  
Author(s):  
Moataz Dowaidar
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mitochondrial Dysfunction ◽  
Senile Plaques ◽  
Mitochondrial Division ◽  
Disease Etiology ◽  
Abnormal Mitochondria ◽  
Unifying Principles

In both in vitro and in vivo Alzheimer's disease (AD) models, mitochondrial dysfunction is a crucial feature that limits neuronal activity and results in A and phosphorylated Tau toxicity. To rectify AD etiology, excessive mitochondrial division might be stopped or mitophagy might be promoted. However, there are still unexplained mysteries surrounding the formation of senile plaques and NFTs, and the pathophysiology of Alzheimer's disease lacks fundamental unifying principles. Some scientists believe A toxicity and Tau toxicity are upstream processes in mitochondrial dysfunction, while others feel it is a downstream chain of events involving abnormal mitochondria. There are several mitophagy mechanisms for the clearance of dead mitochondria in PINK1 signaling; some are regulated by Parkin, while others are not. Drp1, Mfn1/2, PINK1, or Parkin, according to some researchers, have no role in mitophagy cleaning dysfunctional mitochondria; so, additional study is needed to solve the puzzle of mitophagy signaling pathways for clearing dead mitochondria and conserving high-quality mitochondria. Therapeutic techniques targeting mitophagy activity might be useful in reversing AD etiology.

scholarly journals The Role of Mitochondrial Dysfunction and ER Stress in TDP-43 and C9ORF72 ALS

2021 ◽  
Vol 15 ◽  
Author(s):  
Ruxandra Dafinca ◽  
Paola Barbagallo ◽  
Kevin Talbot
Keyword(s):  
Er Stress ◽  
Mitochondrial Dysfunction ◽  
Unfolded Protein Response ◽  
Nucleocytoplasmic Transport ◽  
Cellular Processes ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of the motor system with complex determinants, including genetic and non-genetic factors. Despite this heterogeneity, a key pathological signature is the mislocalization and aggregation of specific proteins in the cytoplasm, suggesting that convergent pathogenic mechanisms focusing on disturbances in proteostasis are important in ALS. In addition, many cellular processes have been identified as potentially contributing to disease initiation and progression, such as defects in axonal transport, autophagy, nucleocytoplasmic transport, ER stress, calcium metabolism, the unfolded protein response and mitochondrial function. Here we review the evidence from in vitro and in vivo models of C9ORF72 and TDP-43-related ALS supporting a central role in pathogenesis for endoplasmic reticulum stress, which activates an unfolded protein response (UPR), and mitochondrial dysfunction. Disruption in the finely tuned signaling between the ER and mitochondria through calcium ions may be a crucial trigger of mitochondrial deficits and initiate an apoptotic signaling cascade, thus acting as a point of convergence for multiple upstream disturbances of cellular homeostasis and constituting a potentially important therapeutic target.

scholarly journals Quercetin Attenuates Cardiac Hypertrophy by Inhibiting Mitochondrial Dysfunction Through SIRT3/PARP-1 Pathway

2021 ◽  
Vol 12 ◽  
Author(s):  
Wen-Jing Chen ◽  
Yan Cheng ◽  
Wen Li ◽  
Xiao-Kang Dong ◽  
Jian-liang Wei ◽  
...  
Keyword(s):  
Cardiac Hypertrophy ◽  
Protective Effect ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Mrna Level ◽  
Hypertensive Heart Disease ◽  
Ang Ii ◽  
Parp 1

Cardiac hypertrophy is an important characteristic in the development of hypertensive heart disease. Mitochondrial dysfunction plays an important role in the pathology of cardiac hypertrophy. Recent studies have shown that sirtuin 3 (SIRT3)/poly (ADP-ribose) polymerase-1 (PARP-1) pathway modulation inhibits cardiac hypertrophy. Quercetin, a natural flavonol agent, has been reported to attenuate cardiac hypertrophy. However, the molecular mechanism is not completely elucidated. In this study, we aimed to explore the mechanism underlying the protective effect of quercetin on cardiac hypertrophy. Spontaneously hypertensive rats (SHRs) were treated with quercetin (20 mg/kg/d) for 8 weeks to evaluate the effects of quercetin on blood pressure and cardiac hypertrophy. Additionally, the mitochondrial protective effect of quercetin was assessed in H9c2 cells treated with Ang II. SHRs displayed aggravated cardiac hypertrophy and fibrosis, which were attenuated by quercetin treatment. Quercetin also improved cardiac function, reduced mitochondrial superoxide and protected mitochondrial structure in vivo. In vitro, Ang II increased the mRNA level of hypertrophic markers including atrial natriuretic factor (ANF) and β-myosin heavy chain (β-MHC), whereas quercetin ameliorated this hypertrophic response. Moreover, quercetin prevented mitochondrial function against Ang II induction. Importantly, mitochondrial protection and PARP-1 inhibition by quercetin were partly abolished after SIRT3 knockdown. Our results suggested that quercetin protected mitochondrial function by modulating SIRT3/PARP-1 pathway, contributing to the inhibition of cardiac hypertrophy.

scholarly journals Huaier Cream Protects against Adriamycin-Induced Nephropathy by Restoring Mitochondrial Function via PGC-1αUpregulation

PPAR Research ◽  
2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Ruochen Che ◽  
Chunhua Zhu ◽  
Guixia Ding ◽  
Min Zhao ◽  
Mi Bai ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Cell Injury ◽  
Therapeutic Drug ◽  
Mtdna Copy Number ◽  
Glomerular Diseases ◽  
Mitochondrial Transcription Factor ◽  
Transmission Electron

The mechanism by which Huaier, a Chinese traditional medicine, protects podocytes remains unclear. We designed the present study to examine whether mitochondrial function restored by PGC-1αserves as the major target of Huaier cream in protecting ADR nephropathy. After ADR administration, the podocytes exhibited remarkable cell injury and mitochondrial dysfunction. Additionally, ADR also reduced PGC-1αbothin vivoandin vitro. Following the Huaier treatment, the notable downregulation of PGC-1αand its downstream molecule mitochondrial transcription factor A (TFAM) were almost entirely blocked. Correspondingly, Huaier markedly ameliorated ADR-induced podocyte injury and mitochondrial dysfunction in both rat kidneys and incubated cells as it inhibited the decrease of nephrin and podocin expression, mtDNA copy number, MMP, and ATP content. Transmission electron microscopy result also showed that Huaier protected mitochondria against ADR-induced severe mitophagy and abnormal changes of ultrastructural morphology. In conclusion, Huaier can protect podocytes against ADR-induced cytotoxicity possibly by reversing the dysfunction of mitochondria via PGC-1αoverexpression, which may be a novel therapeutic drug target in glomerular diseases.

scholarly journals TRAP1 Provides Protection Against Myocardial Ischemia-Reperfusion Injury by Ameliorating Mitochondrial Dysfunction

2015 ◽  
Vol 36 (5) ◽  
pp. 2072-2082 ◽  
Author(s):  
Peng Zhang ◽  
Yong Lu ◽  
Dong Yu ◽  
Dadong Zhang ◽  
Wei Hu
Keyword(s):  
Cell Death ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Ros Generation ◽  
Complex Activity ◽  
Atp Production

Background: Tumor necrosis factor receptor-associated protein 1 (TRAP1), an essential mitochondrial chaperone is induced in rat hearts following ischemia/reperfusion (I/R), but its role in myocardial I/R injury is unclear. The present study examined the function of TRAP1 in cardiomyocyte hypoxia/reoxygenation injury in vitro and myocardial I/R injury in vivo. Methods: HL-1 cardiomyocytes transfected with TRAP1 or vector were subjected to simulated I/R (SI/R) in vitro. Cell death and mitochondrial function were assessed. Wild type (WT) and TRAP1 knockout (TRAP1 KO) mice were subjected to cardiac I/R in vivo. The infarct size and myocardial apoptosis were determined. WT and TRAP1 KO cardiomyocytes were subjected to SI/R in vitro. Mitochondrial function was assessed. Results: TRAP1 overexpression protects HL-1 cardiomyocytes from SI/R-induced cell death in vitro. The reduced cell death was associated with decreased ROS generation, better-preserved mitochondrial ETC complex activity, membrane potential, and ATP production, as well as delayed mPTP opening. Loss of TRAP1 aggravates SI/R-induced mitochondrial damage in cardiomyocytes in vitro and myocardial I/R injury and apoptosis in vivo. Conclusion: The results of the present study show that TRAP1 provides cardioprotection against myocardial I/R by ameliorating mitochondrial dysfunction.

scholarly journals Chronic Cadmium Exposure Impairs Macrophage Mitochondrial Homeostasis and Promotes Macrophage Polarization Contributing to Atherosclerosis via Regulating RIPK3 Signaling

2021 ◽  
Author(s):  
Jiexin Zhang ◽  
Weijing Feng ◽  
Peier Chen ◽  
Xiaodong Ning ◽  
Caiwen Ou ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Macrophage Polarization ◽  
Mitochondrial Fission ◽  
Inflammatory Factors ◽  
Mitochondrial Homeostasis ◽  
Cd Exposure ◽  
M1 Type

Abstract Background: Chronic cadmium (Cd) exposure can contribute to the progression of cardiovascular disease (CVD), especially atherosclerosis (AS), but the underlying mechanism is unclear. Since mitochondrial homeostasis is emerging as a core player in the development of CVD, it might serve as a potential mechanism linking Cd exposure and AS. Here, we aimed to investigate the Cd-induced AS through macrophage polarization and tried to find out the mechanism of mitochondrial dysfunction caused by Cd exposure. Methods and results: In vitro, flow cytometry showed that Cd exposure markedly promoted M1-type polarization of macrophages, manifesting as the increasing expression of NF-kB, NLRP3 and their downstream inflammatory factors, IL-1β and IL-6. Mitochondrial function test revealed that the decreasing mitochondrial membrane potential and increasing superoxide (mROS) and mitochondrial fission were involved in Cd-induced macrophage polarization. Transmission electron microscope observation and immunofluorescence both identified the decrease of mitophage after Cd exposure. And improving mitochondrial function above significantly restored the balance of macrophage polarization. In vivo, Cd exposure was positively correlated with blood Cd concentration, and oil red O staining showed higher blood Cd significantly increased the area of AS plaques. Besides, M1-type polarization of macrophages and mitochondrial dysfunction were observed in mouse aortic roots through immunofluorescence and western blot as the dosage of Cd increasing. And the administered NAC or Mdivi-1, which decreased mROS or mitochondrial fission, markedly attenuated AS plaques and macrophage M1-type polarization in Cd-treated group. Finally, the up-regulated expressions of RIPK3 and p-MLKL were observed both in vitro and in vivo. And knocking out RIPK3 with decreasing expression of p-MLKL followed did improve mitochondrial dysfunction caused by Cd which effectively reversed macrophage polarization. Conclusion: Cd exposure activated RIPK3 pathway and impaired mitochondrial homeostasis, resulting in macrophage polarization to a pro-inflammatory phenotype and subsequent AS. These findings suggest that improving mitochondrial homeostasis may provide a potential therapeutic target for AS induced by chronic Cd exposure.

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