scholarly journals Drp1-mediated mitochondrial fission regulates calcium and F-actin dynamics during wound healing

2019 ◽  
Author(s):  
Susana Ponte ◽  
Lara Carvalho ◽  
Maria Gagliardi ◽  
Isabel Campos ◽  
Paulo J. Oliveira ◽  
...  
Keyword(s):  
Wound Healing ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Actin Dynamics ◽  
Mitochondrial Calcium ◽  
Loss Of Function ◽  
Wound Edge ◽  
Epithelial Repair ◽  
Healing Impairment

AbstractMitochondria adapt to cellular needs by changes in morphology through fusion and fission events, referred to as mitochondrial dynamics. Mitochondrial function and morphology are intimately connected and the dysregulation of mitochondrial dynamics is linked to several human diseases. In this work, we investigated the role of mitochondrial dynamics in wound healing in the Drosophila embryonic epidermis. Mutants for mitochondrial fusion and fission proteins fail to close their wounds, indicating that the regulation of mitochondrial dynamics is required for wound healing. By live-imaging, we found that loss of function of the mitochondrial fission protein Dynamin-related protein 1 (Drp1) compromises the increase of cytosolic and mitochondrial calcium upon wounding and leads to F-actin defects at the wound edge, culminating in wound healing impairment. Our results highlight a new role for mitochondrial dynamics in the regulation of calcium and F-actin during epithelial repair.SummaryWe show that mitochondrial dynamics proteins are required for epithelial repair. In particular, Drp1 loss-of-function leads to defects in the dynamics of cytosolic and mitochondrial calcium and F-actin upon wounding.

scholarly journals Syntaxin-17-Dependent Mitochondrial Dynamics is Essential for Protection Against Oxidative-Stress-Induced Apoptosis

Antioxidants ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 522 ◽  
Author(s):  
Wang ◽  
Xiao ◽  
Huang ◽  
Liu
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Autophagic Flux ◽  
Wild Type ◽  
Dual Roles ◽  
Defective Mutant ◽  
U2os Cells ◽  
Induced Apoptosis

In this study, cell death induced by the oxidant tert-butylhydroperoxide (tBH) was observed in U2OS cells; this phenotype was rescued by Syntaxin 17 (STX17) knockout (KO) but the mechanism is unknown. STX17 plays dual roles in autophagosome–lysosome fusion and mitochondrial fission. However, the contribution of the two functions of STX17 to apoptosis has not been extensively studied. Here, we sought to dissect the dual roles of STX17 in oxidative-stress-induced apoptosis by taking advantage of STX17 knockout cells and an autophagosome–lysosome fusion defective mutant of STX17. We generated STX17 knockout U2OS cells using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system and the STX17 knockout cells were reconstituted with wild-type STX17 and its autophagosome–lysosome fusion defective mutant. Autophagy was assessed by autophagic flux assay, Monomer red fluorescent protein (mRFP)–GFP–LC3 assay and protease protection assay. Golgi, endoplasmic reticulum (ER)/ER–Golgi intermediate compartment (ERGIC) and mitochondrial dynamics were examined by staining the different indicator proteins. Apoptosis was evaluated by caspase cleavage assay. The general reactive oxygen species (ROS) were detected by flow cytometry. In STX17 complete knockout cells, sealed autophagosomes were efficiently formed but their fusion with lysosomes was less defective. The fusion defect was rescued by wild-type STX17 but not the autophagosome–lysosome fusion defective mutant. No obvious defects in Golgi, ERGIC or ER dynamics were observed. Mitochondria were significantly elongated, supporting a role of STX17 in mitochondria fission and the elongation caused by STX17 KO was reversed by the autophagosome–lysosome fusion defective mutant. The clearance of protein aggregation was compromised, correlating with the autophagy defect but not with mitochondrial dynamics. This study revealed a mixed role of STX17 in autophagy, mitochondrial dynamics and oxidative stress response. STX17 knockout cells were highly resistant to oxidative stress, largely due to the function of STX17 in mitochondrial fission rather than autophagy.

scholarly journals Non-alcoholic fatty liver disease in mice with hepatocyte-specific deletion of mitochondrial fission factor

Diabetologia ◽  
2021 ◽  
Author(s):  
Yukina Takeichi ◽  
Takashi Miyazawa ◽  
Shohei Sakamoto ◽  
Yuki Hanada ◽  
Lixiang Wang ◽  
...  
Keyword(s):  
Er Stress ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Primary Hepatocytes ◽  
Alcoholic Fatty Liver ◽  
Expression Of Genes ◽  
Specific Deletion

Abstract Aims/hypothesis Mitochondria are highly dynamic organelles continuously undergoing fission and fusion, referred to as mitochondrial dynamics, to adapt to nutritional demands. Evidence suggests that impaired mitochondrial dynamics leads to metabolic abnormalities such as non-alcoholic steatohepatitis (NASH) phenotypes. However, how mitochondrial dynamics are involved in the development of NASH is poorly understood. This study aimed to elucidate the role of mitochondrial fission factor (MFF) in the development of NASH. Methods We created mice with hepatocyte-specific deletion of MFF (MffLiKO). MffLiKO mice fed normal chow diet (NCD) or high-fat diet (HFD) were evaluated for metabolic variables and their livers were examined by histological analysis. To elucidate the mechanism of development of NASH, we examined the expression of genes related to endoplasmic reticulum (ER) stress and lipid metabolism, and the secretion of triacylglycerol (TG) using the liver and primary hepatocytes isolated from MffLiKO and control mice. Results MffLiKO mice showed aberrant mitochondrial morphologies with no obvious NASH phenotypes during NCD, while they developed full-blown NASH phenotypes in response to HFD. Expression of genes related to ER stress was markedly upregulated in the liver from MffLiKO mice. In addition, expression of genes related to hepatic TG secretion was downregulated, with reduced hepatic TG secretion in MffLiKO mice in vivo and in primary cultures of MFF-deficient hepatocytes in vitro. Furthermore, thapsigargin-induced ER stress suppressed TG secretion in primary hepatocytes isolated from control mice. Conclusions/interpretation We demonstrated that ablation of MFF in liver provoked ER stress and reduced hepatic TG secretion in vivo and in vitro. Moreover, MffLiKO mice were more susceptible to HFD-induced NASH phenotype than control mice, partly because of ER stress-induced apoptosis of hepatocytes and suppression of TG secretion from hepatocytes. This study provides evidence for the role of mitochondrial fission in the development of NASH. Graphical abstract

scholarly journals T-2 Toxin-Induced Oxidative Stress Leads to Imbalance of Mitochondrial Fission and Fusion to Activate Cellular Apoptosis in the Human Liver 7702 Cell Line

Toxins ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 43 ◽  
Author(s):  
Junhua Yang ◽  
Wenbo Guo ◽  
Jianhua Wang ◽  
Xianli Yang ◽  
Zhiqi Zhang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Apoptosis ◽  
Human Liver ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Mitochondrial Fusion ◽  
Mitochondrial Dynamic ◽  
Normal Human Liver ◽  
Induced Apoptosis

T-2 toxin, as a highly toxic mycotoxin to humans and animals, induces oxidative stress and apoptosis in various cells and tissues. Apoptosis and mitochondrial fusion/fission are two tightly interconnected processes that are crucial for maintaining physiological homeostasis. However, the role of mitochondrial fusion/fission in apoptosis of T-2 toxin remains unknown. Hence, we aimed to explore the putative role of mitochondrial fusion/fission on T-2 toxin induced apoptosis in normal human liver (HL-7702) cells. T-2 toxin treatment (0, 0.1, 1.0, or 10 μg/L) for 24 h caused decreased cell viability and ATP concentration and increased production of (ROS), as seen by a loss of mitochondrial membrane potential (∆Ψm) and increase in mitochondrial fragmentation. Subsequently, the mitochondrial dynamic imbalance was activated, evidenced by a dose-dependent decrease and increase in the protein expression of mitochondrial fusion (OPA1, Mfn1, and Mfn2) and fission (Drp1 and Fis1), respectively. Furthermore, the T-2 toxin promoted the release of cytochrome c from mitochondria to cytoplasm and induced cell apoptosis triggered by upregulation of Bax and Bax/Bcl-2 ratios, and further activated the caspase pathways. Taken together, these results indicate that altered mitochondrial dynamics induced by oxidative stress with T-2 toxin exposure likely contribute to mitochondrial injury and HL-7702 cell apoptosis.

scholarly journals The Abl-interactor Abi suppresses the function of the BRAG2 GEF family member Schizo

2020 ◽  
Author(s):  
Stefanie Lübke ◽  
Carina Braukmann ◽  
Karl-Heinz Rexer ◽  
Lubjinka Cigoja ◽  
Susanne F. Önel
Keyword(s):  
Family Member ◽  
Guanine Nucleotide Exchange Factors ◽  
Actin Dynamics ◽  
Nucleotide Exchange ◽  
Ph Domain ◽  
Loss Of Function ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Arf Gtpases

AbstractGuanine nucleotide exchange factors (GEF) of the BRAG subfamily activate small Arf GTPases, which are pivotal regulators of intracellular membrane traffic and actin dynamics. Here, we demonstrate a novel interaction between the Abl-interactor (Abi) and the BRAG family member Schizo. We mapped the SH3 domain of Abi to interact with the N-terminal region of Schizo. This region is additionally involved in the binding of the cytodomain of the cell adhesion molecule N-cadherin. In schizo loss of function mutants, we detected increased amounts of N-cadherin. In contrast, the expression of the GEF (Sec7) and the membrane-binding (pleckstrin homology) domains decreased amounts of N-cadherin, indicating a crucial role of the Sec7-PH module in regulating N-cadherin levels. Unlike other Sec7 GEFs, where the catalytic Sec7 domain is autoinhibited, the Sec7 and PH domain of BRAG2 are constitutively accessible, raising the question how GEF activity is controlled in a spatial and temporal manner. Our genetic analyzes demonstrate that the nature of the Abi Schizo interaction is to antagonize Schizo function and to restore wild-type amounts of N-cadherin.

scholarly journals Protective Effects of Anti-depressant Citalopram Against Abnormal APP Processing and Amyloid Beta-induced Mitochondrial Dynamics, Biogenesis, Mitophagy and Synaptic Toxicities in Alzheimer’s Disease

2021 ◽  
Author(s):  
Arubala P Reddy ◽  
Xiangling Yin ◽  
Neha Sawant ◽  
P Hemachandra Reddy
Keyword(s):  
Electron Microscopy ◽  
Alzheimer’S Disease ◽  
Transmission Electron Microscopy ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Protective Role ◽  
Mrna Levels ◽  
Ht22 Cells ◽  
Transmission Electron

Abstract The purpose of this study is to study the neuroprotective role of selective serotonin reuptake inhibitor (SSRI), citalopram against Alzheimer’s disease (ad). Multiple SSRIs, including citalopram are reported to treat patients with depression, anxiety, and ad. However, their protective cellular mechanisms have not been studied completely. In the current study, we investigated the protective role of citalopram against impaired mitochondrial dynamics, defective mitochondrial biogenesis, defective mitophagy, and synaptic dysfunction in immortalized mouse primary hippocampal cells (HT22) expressing mutant APP (SWI/IND) mutations. Using quantitative RT-PCR, immunoblotting, biochemical methods and transmission electron microscopy methods, we assessed mutant full-length APP/C-terminal fragments and Aβ levels and mRNA and protein levels of mitochondrial dynamics, biogenesis, mitophagy, and synaptic genes in mAPP-HT22 cells and mAPP-HT22 cells treated with citalopram. Increased levels of mRNA levels of mitochondrial fission genes, decreased levels of fusion biogenesis, autophagy, mitophagy and synaptic genes were found in mAPP-HT22 cells relative to WT-HT22 cells. However, in mAPP-HT22 cells treated with citalopram compared to mAPP-HT22 cells, revealed reduced levels of the mitochondrial fission genes, increased fusion, biogenesis, autophagy, mitophagy, and synaptic genes. Our protein data agrees with mRNA levels. Transmission electron microscopy revealed significantly increased mitochondrial numbers and reduced mitochondrial length in mAPP-HT22 cells; these were reversed in citalopram treated mAPP-HT22 cells. Cell survival rates were increased in citalopram treated mAPP-HT22 relative to citalopram-untreated mAPP-HT22. Further, mAPP and C-terminal fragments were also reduced in citalopram treated cells. These findings suggest that citalopram reduces mutant APP and Aβ and mitochondrial toxicities and may have a protective role of mutant APP and Aβ-induced injuries in patients with depression, anxiety, and ad.

scholarly journals Role of GTPase-Dependent Mitochondrial Dynamins in Heart Diseases

2021 ◽  
Vol 8 ◽  
Author(s):  
Jiangen Liu ◽  
Xianjing Song ◽  
Youyou Yan ◽  
Bin Liu
Keyword(s):  
Cell Function ◽  
Morphological Changes ◽  
Heart Function ◽  
Mitochondrial Dynamics ◽  
Heart Diseases ◽  
Ischemia Reperfusion ◽  
Mitochondrial Fission ◽  
Mitochondrial Fusion ◽  
Dependent Manner

Heart function maintenance requires a large amount of energy, which is supplied by the mitochondria. In addition to providing energy to cardiomyocytes, mitochondria also play an important role in maintaining cell function and homeostasis. Although adult cardiomyocyte mitochondria appear as independent, low-static organelles, morphological changes have been observed in cardiomyocyte mitochondria under stress or pathological conditions. Indeed, cardiac mitochondrial fission and fusion are involved in the occurrence and development of heart diseases. As mitochondrial fission and fusion are primarily regulated by mitochondrial dynamins in a GTPase-dependent manner, GTPase-dependent mitochondrial fusion (MFN1, MFN2, and OPA1) and fission (DRP1) proteins, which are abundant in the adult heart, can also be regulated in heart diseases. In fact, these dynamic proteins have been shown to play important roles in specific diseases, including ischemia-reperfusion injury, heart failure, and metabolic cardiomyopathy. This article reviews the role of GTPase-dependent mitochondrial fusion and fission protein-mediated mitochondrial dynamics in the occurrence and development of heart diseases.

Mitochondrial protein 18 is a positive apoptotic regulator in cardiomyocytes under oxidative stress

2019 ◽  
Vol 133 (9) ◽  
pp. 1067-1084 ◽  
Author(s):  
Lynn H.H. Aung ◽  
Yu-Zhen Li ◽  
Hua Yu ◽  
Xiatian Chen ◽  
Zhongjie Yu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Mitochondrial Protein ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Cardiac Apoptosis ◽  
Inner Membrane Protein ◽  
Artery Disease ◽  
Subsequent Activation

AbstractAccumulation of reactive oxygen species is a common phenomenon in cardiac stress conditions, for instance, coronary artery disease, aging-related cardiovascular abnormalities, and exposure to cardiac stressors such as hydrogen peroxide (H2O2). Mitochondrial protein 18 (Mtp18) is a novel mitochondrial inner membrane protein, shown to involve in the regulation of mitochondrial dynamics. Although Mtp18 is abundant in cardiac muscles, its role in cardiac apoptosis remains elusive. The present study aimed to detect the role of Mtp18 in H2O2-induced mitochondrial fission and apoptosis in cardiomyocytes. We studied the effect of Mtp18 in cardiomyocytes by modulating its expression with lentiviral construct of Mtp18-shRNA and Mtp18 c-DNA, respectively. We then analyzed mitochondrial morphological dynamics with MitoTracker Red staining; apoptosis with terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL) and cell death detection assays; and protein expression with immunoblotting. Here, we observed that Mtp18 could regulate oxidative stress- mediated mitochondrial fission and apoptosis in cardiac myocytes. Mechanistically, we found that Mtp8 induced mitochondrial fission and apoptosis by enhancing dynamin-related protein 1 (Drp1) accumulation. Conversely, knockdown of Mtp18 interfered with Drp1-associated mitochondrial fission and subsequent activation of apoptosis in both HL-1 cells and primary cardiomyocytes. However, overexpression of Mtp18 alone was not sufficient to execute apoptosis when Drp1 was minimally expressed, suggesting that Mtp18 and Drp1 are interdependent in apoptotic cascade. Together, these data highlight the role of Mtp18 in cardiac apoptosis and provide a novel therapeutic insight to minimize cardiomyocyte loss via targetting mitochondrial dynamics.

scholarly journals A Disturbance in the Force: Cellular Stress Sensing by the Mitochondrial Network

Antioxidants ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 126 ◽  
Author(s):  
Robert Gilkerson
Keyword(s):  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Cellular Stress ◽  
Cellular Stress Response ◽  
Mitochondrial Network ◽  
Key Factors ◽  
Highly Sensitive ◽  
Integral Role ◽  
Stress Sensing

As a highly dynamic organellar network, mitochondria are maintained as an organellar network by delicately balancing fission and fusion pathways. This homeostatic balance of organellar dynamics is increasingly revealed to play an integral role in sensing cellular stress stimuli. Mitochondrial fission/fusion balance is highly sensitive to perturbations such as loss of bioenergetic function, oxidative stress, and other stimuli, with mechanistic contribution to subsequent cell-wide cascades including inflammation, autophagy, and apoptosis. The overlapping activity with m-AAA protease 1 (OMA1) metallopeptidase, a stress-sensitive modulator of mitochondrial fusion, and dynamin-related protein 1 (DRP1), a regulator of mitochondrial fission, are key factors that shape mitochondrial dynamics in response to various stimuli. As such, OMA1 and DRP1 are critical factors that mediate mitochondrial roles in cellular stress-response signaling. Here, we explore the current understanding and emerging questions in the role of mitochondrial dynamics in sensing cellular stress as a dynamic, responsive organellar network.

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