DRP1 Inhibition Rescues Mitochondrial Integrity and Excessive Apoptosis in CS-A Disease Cell Models

Cockayne syndrome group A (CS-A) is a rare recessive progeroid disorder characterized by sun sensitivity and neurodevelopmental abnormalities. Cells derived from CS-A patients present as pathological hallmarks excessive oxidative stress, mitochondrial fragmentation and apoptosis associated with hyperactivation of the mitochondrial fission dynamin related protein 1 (DRP1). In this study, by using human cell models we further investigated the interplay between DRP1 and CSA and we determined whether pharmacological or genetic inhibition of DRP1 affects disease progression. Both reactive oxygen and nitrogen species are in excess in CS-A cells and when the mitochondrial translocation of DRP1 is inhibited a reduction of these species is observed together with a recovery of mitochondrial integrity and a significant decrease of apoptosis. This study indicates that the CSA-driven modulation of DRP1 pathway is key to control mitochondrial homeostasis and apoptosis and suggests DRP1 as a potential target in the treatment of CS patients.

Download Full-text

Chlamydia preserves the mitochondrial network necessary for replication via microRNA-dependent inhibition of fission

The Journal of Cell Biology ◽

10.1083/jcb.201608063 ◽

2017 ◽

Vol 216 (4) ◽

pp. 1071-1089 ◽

Cited By ~ 43

Author(s):

Suvagata Roy Chowdhury ◽

Anastasija Reimer ◽

Malvika Sharan ◽

Vera Kozjak-Pavlovic ◽

Ana Eulalio ◽

...

Keyword(s):

Target Gene ◽

Mitochondrial Fission ◽

Host Cells ◽

Mitochondrial Network ◽

Mitochondrial Fragmentation ◽

Obligate Intracellular ◽

Mitochondrial Integrity ◽

Dependent Inhibition ◽

Infected Cells ◽

Obligate Intracellular Bacteria

Obligate intracellular bacteria such as Chlamydia trachomatis depend on metabolites of the host cell and thus protect their sole replication niche by interfering with the host cells’ stress response. Here, we investigated the involvement of host microRNAs (miRNAs) in maintaining the viability of C. trachomatis–infected primary human cells. We identified miR-30c-5p as a prominently up-regulated miRNA required for the stable down-regulation of p53, a major suppressor of metabolite supply in C. trachomatis–infected cells. Loss of miR-30c-5p led to the up-regulation of Drp1, a mitochondrial fission regulator and a target gene of p53, which, in turn, severely affected chlamydial growth and had a marked effect on the mitochondrial network. Drp1-induced mitochondrial fragmentation prevented replication of C. trachomatis even in p53-deficient cells. Additionally, Chlamydia maintain mitochondrial integrity during reactive oxygen species–induced stress that occurs naturally during infection. We show that C. trachomatis require mitochondrial ATP for normal development and hence postulate that they preserve mitochondrial integrity through a miR-30c-5p–dependent inhibition of Drp1-mediated mitochondrial fission.

Download Full-text

Ca2+ imbalance caused by ERdj5 deletion affects mitochondrial fragmentation

Scientific Reports ◽

10.1038/s41598-021-99980-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Riyuji Yamashita ◽

Shohei Fujii ◽

Ryo Ushioda ◽

Kazuhiro Nagata

Keyword(s):

Cellular Senescence ◽

Calcium Ion ◽

Mitochondrial Fission ◽

Redox Activity ◽

Signalling Pathways ◽

Protein Homeostasis ◽

Mitochondrial Fragmentation ◽

Mitochondrial Homeostasis ◽

Disulfide Reductase ◽

Intracellular Ca

AbstractThe endoplasmic reticulum (ER) is the organelle responsible for the folding of secretory/membrane proteins and acts as a dynamic calcium ion (Ca2+) store involved in various cellular signalling pathways. Previously, we reported that the ER-resident disulfide reductase ERdj5 is involved in the ER-associated degradation (ERAD) of misfolded proteins in the ER and the activation of SERCA2b, a Ca2+ pump on the ER membrane. These results highlighted the importance of the regulation of redox activity in both Ca2+ and protein homeostasis in the ER. Here, we show that the deletion of ERdj5 causes an imbalance in intracellular Ca2+ homeostasis, the activation of Drp1, a cytosolic GTPase involved in mitochondrial fission, and finally the aberrant fragmentation of mitochondria, which affects cell viability as well as phenotype with features of cellular senescence. Thus, ERdj5-mediated regulation of intracellular Ca2+ is essential for the maintenance of mitochondrial homeostasis involved in cellular senescence.

Download Full-text

Faculty Opinions recommendation of Mitochondrial fission and cristae disruption increase the response of cell models of Huntington's disease to apoptotic stimuli.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.6516956.6647054 ◽

2010 ◽

Author(s):

Stefano Di Donato

Keyword(s):

Huntington's Disease ◽

Huntington’S Disease ◽

Mitochondrial Fission ◽

Cell Models

Download Full-text

Mitochondrial fission and mitophagy are independent mechanisms regulating ischemia/reperfusion injury in primary neurons

Cell Death and Disease ◽

10.1038/s41419-021-03752-2 ◽

2021 ◽

Vol 12 (5) ◽

Author(s):

Anthony R. Anzell ◽

Garrett M. Fogo ◽

Zoya Gurm ◽

Sarita Raghunayakula ◽

Joseph M. Wider ◽

...

Keyword(s):

Cortical Neurons ◽

Ischemia Reperfusion Injury ◽

Mitochondrial Dynamics ◽

Ischemia Reperfusion ◽

Mitochondrial Fission ◽

Conditional Knockout ◽

Mitochondrial Morphology ◽

Primary Neurons ◽

Mitochondrial Fragmentation

AbstractMitochondrial dynamics and mitophagy are constitutive and complex systems that ensure a healthy mitochondrial network through the segregation and subsequent degradation of damaged mitochondria. Disruption of these systems can lead to mitochondrial dysfunction and has been established as a central mechanism of ischemia/reperfusion (I/R) injury. Emerging evidence suggests that mitochondrial dynamics and mitophagy are integrated systems; however, the role of this relationship in the context of I/R injury remains unclear. To investigate this concept, we utilized primary cortical neurons isolated from the novel dual-reporter mitochondrial quality control knockin mice (C57BL/6-Gt(ROSA)26Sortm1(CAG-mCherry/GFP)Ganl/J) with conditional knockout (KO) of Drp1 to investigate changes in mitochondrial dynamics and mitophagic flux during in vitro I/R injury. Mitochondrial dynamics was quantitatively measured in an unbiased manner using a machine learning mitochondrial morphology classification system, which consisted of four different classifications: network, unbranched, swollen, and punctate. Evaluation of mitochondrial morphology and mitophagic flux in primary neurons exposed to oxygen-glucose deprivation (OGD) and reoxygenation (OGD/R) revealed extensive mitochondrial fragmentation and swelling, together with a significant upregulation in mitophagic flux. Furthermore, the primary morphology of mitochondria undergoing mitophagy was classified as punctate. Colocalization using immunofluorescence as well as western blot analysis revealed that the PINK1/Parkin pathway of mitophagy was activated following OGD/R. Conditional KO of Drp1 prevented mitochondrial fragmentation and swelling following OGD/R but did not alter mitophagic flux. These data provide novel evidence that Drp1 plays a causal role in the progression of I/R injury, but mitophagy does not require Drp1-mediated mitochondrial fission.

Download Full-text

Urine-Derived Epithelial Cells as Models for Genetic Kidney Diseases

Cells ◽

10.3390/cells10061413 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1413

Author(s):

Tjessa Bondue ◽

Fanny O. Arcolino ◽

Koenraad R. P. Veys ◽

Oyindamola C. Adebayo ◽

Elena Levtchenko ◽

...

Keyword(s):

Epithelial Cells ◽

Kidney Diseases ◽

Cell Types ◽

Cell Models ◽

Tubular Epithelial Cells ◽

Disease Mechanisms ◽

Proximal Tubular Epithelial Cells ◽

Proximal Tubular ◽

Disease Cell

Epithelial cells exfoliated in human urine can include cells anywhere from the urinary tract and kidneys; however, podocytes and proximal tubular epithelial cells (PTECs) are by far the most relevant cell types for the study of genetic kidney diseases. When maintained in vitro, they have been proven extremely valuable for discovering disease mechanisms and for the development of new therapies. Furthermore, cultured patient cells can individually represent their human sources and their specific variants for personalized medicine studies, which are recently gaining much interest. In this review, we summarize the methodology for establishing human podocyte and PTEC cell lines from urine and highlight their importance as kidney disease cell models. We explore the well-established and recent techniques of cell isolation, quantification, immortalization and characterization, and we describe their current and future applications.

Download Full-text

Inhibition of Mitochondrial Dynamics Preferentially Targets Pancreatic Cancer Cells with Enhanced Tumorigenic and Invasive Potential

Cancers ◽

10.3390/cancers13040698 ◽

2021 ◽

Vol 13 (4) ◽

pp. 698

Author(s):

Sarah Courtois ◽

Beatriz de Luxán-Delgado ◽

Laure Penin-Peyta ◽

Alba Royo-García ◽

Beatriz Parejo-Alonso ◽

...

Keyword(s):

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Metastatic Potential ◽

Ductal Adenocarcinoma ◽

Expression Ratio ◽

Cytotoxic Effects ◽

Mitochondrial Homeostasis ◽

Pancreatic Cancer Cells ◽

Tumorigenic Potential ◽

Dose Dependent

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest tumors, partly due to its intrinsic aggressiveness, metastatic potential, and chemoresistance of the contained cancer stem cells (CSCs). Pancreatic CSCs strongly rely on mitochondrial metabolism to maintain their stemness, therefore representing a putative target for their elimination. Since mitochondrial homeostasis depends on the tightly controlled balance between fusion and fission processes, namely mitochondrial dynamics, we aim to study this mechanism in the context of stemness. In human PDAC tissues, the mitochondrial fission gene DNM1L (DRP1) was overexpressed and positively correlated with the stemness signature. Moreover, we observe that primary human CSCs display smaller mitochondria and a higher DRP1/MFN2 expression ratio, indicating the activation of the mitochondrial fission. Interestingly, treatment with the DRP1 inhibitor mDivi-1 induced dose-dependent apoptosis, especially in CD133+ CSCs, due to the accumulation of dysfunctional mitochondria and the subsequent energy crisis in this subpopulation. Mechanistically, mDivi-1 inhibited stemness-related features, such as self-renewal, tumorigenicity, and invasiveness and chemosensitized the cells to the cytotoxic effects of Gemcitabine. In summary, mitochondrial fission is an essential process for pancreatic CSCs and represents an attractive target for designing novel multimodal treatments that will more efficiently eliminate cells with high tumorigenic potential.

Download Full-text

Abstract 431: Mitochondrial Fission in the Heart is an Adaptation to Increased Energetic Demands: The Role of Physiologic Fragmentation

Circulation Research ◽

10.1161/res.119.suppl_1.431 ◽

2016 ◽

Vol 119 (suppl_1) ◽

Author(s):

Michael Coronado ◽

Giovanni Fajardo ◽

Kim Nguyen ◽

Mingming Zhao ◽

Kristina Bezold Kooiker ◽

...

Keyword(s):

Cell Death ◽

Exercise Capacity ◽

Mitochondrial Function ◽

Adrenergic Receptor ◽

Mitochondrial Fission ◽

Physiological Adaptation ◽

Mitochondrial Fragmentation ◽

Energetic Demand ◽

Adaptation To Exercise

Mitochondria play a dual role in the heart, responsible for meeting energetic demands and regulating cell death. Current paradigms hold that mitochondrial fission and fragmentation are the result of pathologic stresses such as ischemia, are an indicator of poor mitochondrial health, and lead to mitophagy and cell death. However, recent studies demonstrate that inhibiting fission also results in cardiac impairment, suggesting that fission is important for maintaining normal mitochondrial function. In this study, we identify a novel role for mitochondrial fragmentation as a normal physiological adaptation to increased energetic demand. Using two models of exercise, we demonstrate that “physiologic” mitochondrial fragmentation occurs, results in enhanced mitochondrial function, and is mediated through beta 1-adrenergic receptor signaling. Similar to pathologic fragmentation, physiologic fragmentation is induced by activation of Drp1; however, unlike pathologic fragmentation, membrane potential is maintained and regulators of mitophagy are downregulated. To confirm the role of fragmentation as a physiological adaptation to exercise, we inhibited the pro-fission mediator Drp1 in mice using the peptide inhibitor P110 and had mice undergo exercise. Mice treated with P110 had significantly decreased exercise capacity, decreased fragmentation and inactive Drp1 vs controls. To further confirm these findings, we generated cardiac-specific Drp1 KO mice and had them undergo exercise. Mice with cardiac specific Drp1 KO had significantly decreased exercise capacity and abnormally large mitochondria compared to controls. These findings indicate the requirement for physiological mitochondrial fragmentation to meet the energetic demands of exercise and support the still evolving conceptual framework, where fragmentation plays a role in the balance between mitochondrial maintenance of normal physiology and response to disease.

Download Full-text

Increased long noncoding RNA maternally expressed gene 3 contributes to podocyte injury induced by high glucose through regulation of mitochondrial fission

Cell Death and Disease ◽

10.1038/s41419-020-03022-7 ◽

2020 ◽

Vol 11 (9) ◽

Author(s):

Qiongxia Deng ◽

Ruowei Wen ◽

Sirui Liu ◽

Xiaoqiu Chen ◽

Shicong Song ◽

...

Keyword(s):

High Glucose ◽

Noncoding Rna ◽

Diabetic Kidney Disease ◽

Mitochondrial Fission ◽

Diabetic Mice ◽

Podocyte Injury ◽

Mitochondrial Translocation ◽

Maternally Expressed Gene 3

Abstract Excessive mitochondrial fission plays a key role in podocyte injury in diabetic kidney disease (DKD), and long noncoding RNAs (lncRNAs) are important in the development and progression of DKD. However, lncRNA regulation of mitochondrial fission in podocytes is poorly understood. Here, we studied lncRNA maternally expressed gene 3 (Meg3) in mitochondrial fission in vivo and in vitro using human podocytes and Meg3 podocyte-specific knockdown mice. Expression of lncRNA Meg3 in STZ-induced diabetic mice was higher, and correlated with the number of podocytes. Excessive mitochondrial fission of podocytes and renal histopathological and physiological parameters were improved in podocyte-specific Meg3 knockdown diabetic mice. Elongated mitochondria with attenuated podocyte damage, as well as mitochondrial translocation of dynamin-related protein 1 (Drp1), were decreased in Meg3 knockout podocytes. By contrast, increased fragmented mitochondria, podocyte injury, and Drp1 expression and phosphorylation were observed in lncRNA Meg3-overexpressing podocytes. Treatment with Mdivi1 significantly blunted more fragmented mitochondria and reduced podocyte injury in lncRNA Meg3-overexpressing podocytes. Finally, fragmented mitochondria and Drp1 mitochondrial translocation induced by high glucose were reduced following treatment with Mdivi1. Our data show that expression of Meg3 in podocytes in both human cells and diabetic mice was higher, which regulates mitochondrial fission and contributes to podocyte injury through increased Drp1 and its translocation to mitochondria.

Download Full-text

Inhibition of mitochondrial fission as a novel therapeutic strategy to reduce mortality upon myocardial infarction

Clinical Science ◽

10.1042/cs20180671 ◽

2018 ◽

Vol 132 (20) ◽

pp. 2163-2167 ◽

Cited By ~ 11

Author(s):

Hannah A. Cooper ◽

Satoru Eguchi

Keyword(s):

Myocardial Infarction ◽

Cardiac Function ◽

Molecular Mechanisms ◽

Ischemia Reperfusion ◽

Mitochondrial Fission ◽

Future Research ◽

Mitochondrial Homeostasis ◽

Acute Mi ◽

Future Research Directions ◽

Receive Treatment

Ischemia reperfusion (I/R) injury is a common event following myocardial infarction (MI) resulting in excessive oxidative stress, calcium overload, inflammation, and cardiomyocyte death. Mitochondrial homeostasis including their dynamics are imbalanced in cardiac I/R injury in favor of increased mitochondrial fission. Inhibition of mitochondrial fission prior to I/R injury is protective and improves cardiac function following MI. Clinically, patients with MI often receive treatment following initiation of the ischemic event. Thus, treatments with more realistic timing would have better translational value and are important to research. In a recent study published in Clinical Science, Maneechote et al. [Clin. Sci. (2018) 132, 1669–1683] examined the effect of inhibiting mitochondrial fission using the mitochondrial division inhibitor (Mdivi-1) at different time points, pre-ischemia, during-ischemia, and upon onset of reperfusion, in a rat cardiac I/R model. The findings showed the greatest cardiac function improvement with pre-ischemia treatment along with decreased mitochondrial fragmentation and increased mitochondrial function. Mdivi-1 given during ischemia and at onset of reperfusion also improved cardiac function, but to a lesser extent than pre-ischemia intervention. Maneechote et al. postulated that the LV protection by Mdivi-1 in cardiac I/R could be due to an improvement in mitochondrial dysfunction through attenuating excessive mitochondrial fission which then reduces apoptotic myocytes. Their findings provide new insights into future treatment of patients suffering acute MI which could consider targetting the excessive mitochondrial fission during cardiac ischemia or at onset of reperfusion. Here, we will further discuss the background of the study, potential molecular mechanisms of mitochondrial fission, consequences of the fission, and future research directions.

Download Full-text

Loss of MCU prevents mitochondrial fusion in G1-S phase and blocks cell cycle progression and proliferation

Science Signaling ◽

10.1126/scisignal.aav1439 ◽

2019 ◽

Vol 12 (579) ◽

pp. eaav1439 ◽

Cited By ~ 19

Author(s):

Olha M. Koval ◽

Emily K. Nguyen ◽

Velarchana Santhana ◽

Trevor P. Fidler ◽

Sara C. Sebag ◽

...

Keyword(s):

Cell Cycle ◽

Cell Proliferation ◽

Cell Cycle Progression ◽

Mitochondrial Fission ◽

Mitochondrial Fusion ◽

Cycle Phase ◽

Wild Type ◽

Mitochondrial Fragmentation ◽

Cycle Progression ◽

Regulatory Circuit

The role of the mitochondrial Ca2+uniporter (MCU) in physiologic cell proliferation remains to be defined. Here, we demonstrated that the MCU was required to match mitochondrial function to metabolic demands during the cell cycle. During the G1-S transition (the cycle phase with the highest mitochondrial ATP output), mitochondrial fusion, oxygen consumption, and Ca2+uptake increased in wild-type cells but not in cells lacking MCU. In proliferating wild-type control cells, the addition of the growth factors promoted the activation of the Ca2+/calmodulin-dependent kinase II (CaMKII) and the phosphorylation of the mitochondrial fission factor Drp1 at Ser616. The lack of the MCU was associated with baseline activation of CaMKII, mitochondrial fragmentation due to increased Drp1 phosphorylation, and impaired mitochondrial respiration and glycolysis. The mitochondrial fission/fusion ratio and proliferation in MCU-deficient cells recovered after MCU restoration or inhibition of mitochondrial fragmentation or of CaMKII in the cytosol. Our data highlight a key function for the MCU in mitochondrial adaptation to the metabolic demands during cell cycle progression. Cytosolic CaMKII and the MCU participate in a regulatory circuit, whereby mitochondrial Ca2+uptake affects cell proliferation through Drp1.

Download Full-text