scholarly journals Cyclin-dependent kinases regulate splice-specific targeting of dynamin-related protein 1 to microtubules

2013 ◽  
Vol 201 (7) ◽  
pp. 1037-1051 ◽  
Author(s):  
Stefan Strack ◽  
Theodore J. Wilson ◽  
J. Thomas Cribbs
Keyword(s):  
Alternative Splicing ◽  
Splice Variants ◽  
Mitochondrial Fission ◽  
Alternative Exon ◽  
Mitochondrial Morphology ◽  
Related Protein ◽  
Fusion Reactions ◽  
Mitochondrial Fragmentation ◽  
Cyclin Dependent Kinases ◽  
And Function

Fission and fusion reactions determine mitochondrial morphology and function. Dynamin-related protein 1 (Drp1) is a guanosine triphosphate–hydrolyzing mechanoenzyme important for mitochondrial fission and programmed cell death. Drp1 is subject to alternative splicing of three exons with previously unknown functional significance. Here, we report that splice variants including the third but excluding the second alternative exon (x01) localized to and copurified with microtubule bundles as dynamic polymers that resemble fission complexes on mitochondria. A major isoform in immune cells, Drp1-x01 required oligomeric assembly and Arg residues in alternative exon 3 for microtubule targeting. Drp1-x01 stabilized and bundled microtubules and attenuated staurosporine-induced mitochondrial fragmentation and apoptosis. Phosphorylation of a conserved Ser residue adjacent to the microtubule-binding exon released Drp1-x01 from microtubules and promoted mitochondrial fragmentation in a splice form–specific manner. Phosphorylation by Cdk1 contributed to dissociation of Drp1-x01 from mitotic microtubules, whereas Cdk5-mediated phosphorylation modulated Drp1-x01 targeting to interphase microtubules. Thus, alternative splicing generates a latent, cytoskeletal pool of Drp1 that is selectively mobilized by cyclin-dependent kinase signaling.

scholarly journals Oxidative stress-induced mitochondrial fragmentation and movement in skeletal muscle myoblasts

2014 ◽  
Vol 306 (12) ◽  
pp. C1176-C1183 ◽  
Author(s):  
Sobia Iqbal ◽  
David A. Hood
Keyword(s):  
Oxidative Stress ◽  
Unfolded Protein Response ◽  
Mitochondrial Morphology ◽  
Related Protein ◽  
Mitochondrial Fragmentation ◽  
Signaling Mechanism ◽  
Unfolded Protein ◽  
Mitochondrial Motility ◽  
And Function ◽  
Protein Response

Mitochondria are dynamic organelles, capable of altering their morphology and function. However, the mechanisms governing these changes have not been fully elucidated, particularly in muscle cells. We demonstrated that oxidative stress with H2O2 resulted in a 41% increase in fragmentation of the mitochondrial reticulum in myoblasts within 3 h of exposure, an effect that was preceded by a reduction in membrane potential. Using live cell imaging, we monitored mitochondrial motility and found that oxidative stress resulted in a 30% reduction in the average velocity of mitochondria. This was accompanied by parallel reductions in both organelle fission and fusion. The attenuation in mitochondrial movement was abolished by the addition of N-acetylcysteine. To investigate whether H2O2-induced fragmentation was mediated by dynamin-related protein 1, we incubated cells with mDivi1, an inhibitor of dynamin-related protein 1 translocation to mitochondria. mDivi1 attenuated oxidative stress-induced mitochondrial fragmentation by 27%. Moreover, we demonstrated that exposure to H2O2 upregulated endoplasmic reticulum-unfolded protein response markers before the initiation of mitophagy signaling and the mitochondrial-unfolded protein response. These findings indicate that oxidative stress is a vital signaling mechanism in the regulation of mitochondrial morphology and motility.

scholarly journals Squamosamide Derivative FLZ Diminishes Aberrant Mitochondrial Fission by Inhibiting Dynamin-Related Protein 1

2021 ◽  
Vol 12 ◽  
Author(s):  
Hanyu Yang ◽  
Lu Wang ◽  
Caixia Zang ◽  
Xu Yang ◽  
Xiuqi Bao ◽  
...  
Keyword(s):  
Mitochondrial Dysfunction ◽  
Dopaminergic Neurons ◽  
Motor Coordination ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Mitochondrial Morphology ◽  
Protective Effects ◽  
Related Protein ◽  
Mitochondrial Fragmentation

Mitochondrial dysfunction is involved in the pathogenesis of Parkinson’s disease (PD). Mitochondrial morphology is dynamic and precisely regulated by mitochondrial fission and fusion machinery. Aberrant mitochondrial fragmentation, which can result in cell death, is controlled by the mitochondrial fission protein, dynamin-related protein 1 (Drp1). Our previous results demonstrated that FLZ could correct mitochondrial dysfunction, but the effect of FLZ on mitochondrial dynamics remain uncharacterized. In this study, we investigated the effect of FLZ and the role of Drp1 on 1-methyl-4-phenylpyridinium (MPP+)–induced mitochondrial fission in neurons. We observed that FLZ blocked Drp1, inhibited Drp1 enzyme activity, and reduced excessive mitochondrial fission in cultured neurons. Furthermore, by inhibiting mitochondrial fission and ROS production, FLZ improved mitochondrial integrity and membrane potential, resulting in neuroprotection. FLZ curtailed the reduction of synaptic branches of primary cultured dopaminergic neurons caused by MPP+ exposure, reduced abnormal fission, restored normal mitochondrial distribution in neurons, and exhibited protective effects on dopaminergic neurons. The in vitro research results were validated using an MPTP-induced PD mouse model. The in vivo results revealed that FLZ significantly reduced the mitochondrial translocation of Drp1 in the midbrain of PD mice, which, in turn, reduced the mitochondrial fragmentation in mouse substantia nigra neurons. FLZ also protected dopaminergic neurons in PD mice and increased the dopamine content in the striatum, which improved the motor coordination ability of the mice. These findings elucidate this newly discovered mechanism through which FLZ produces neuroprotection in PD.

scholarly journals Regulation of the mitochondrial dynamin-like protein Opa1 by proteolytic cleavage

2007 ◽  
Vol 178 (5) ◽  
pp. 757-764 ◽  
Author(s):  
Lorena Griparic ◽  
Takayuki Kanazawa ◽  
Alexander M. van der Bliek
Keyword(s):  
Membrane Potential ◽  
Opposite Effect ◽  
Splice Variants ◽  
Proteolytic Cleavage ◽  
Mitochondrial Morphology ◽  
Intermembrane Space ◽  
Related Protein ◽  
Mitochondrial Fragmentation ◽  
Carbonyl Cyanide ◽  
Mitochondrial Intermembrane Space

The dynamin-related protein Opa1 is localized to the mitochondrial intermembrane space, where it facilitates fusion between mitochondria. Apoptosis causes Opa1 release into the cytosol and causes mitochondria to fragment. Loss of mitochondrial membrane potential also causes mitochondrial fragmentation but not Opa1 release into the cytosol. Both conditions induce the proteolytic cleavage of Opa1, suggesting that mitochondrial fragmentation is triggered by Opa1 inactivation. The opposite effect was observed with knockdown of the mitochondrial intermembrane space protease Yme1. Knockdown of Yme1 prevents the constitutive cleavage of a subset of Opa1 splice variants but does not affect carbonyl cyanide m-chlorophenyl hydrazone or apoptosis-induced cleavage. Knockdown of Yme1 also increases mitochondrial connectivity, but this effect is independent of Opa1 because it also occurs in Opa1 knockdown cells. We conclude that Yme1 constitutively regulates a subset of Opa1 isoforms and an unknown mitochondrial morphology protein, whereas the loss of membrane potential induces the further proteolysis of Opa1.

scholarly journals Adrenergic Regulation of Drp1-Driven Mitochondrial Fission in Cardiac Physio-Pathology

Antioxidants ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 195 ◽  
Author(s):  
Bong Jhun ◽  
Jin O-Uchi ◽  
Stephanie Adaniya ◽  
Michael Cypress ◽  
Yisang Yoon
Keyword(s):  
Mitochondrial Dysfunction ◽  
Molecular Mechanisms ◽  
Mitochondrial Fission ◽  
Ros Generation ◽  
Mitochondrial Morphology ◽  
Mitochondrial Fragmentation ◽  
Cellular Functions ◽  
Post Translational Modifications ◽  
Signaling Activation ◽  
And Function

Abnormal mitochondrial morphology, especially fragmented mitochondria, and mitochondrial dysfunction are hallmarks of a variety of human diseases including heart failure (HF). Although emerging evidence suggests a link between mitochondrial fragmentation and cardiac dysfunction, it is still not well described which cardiac signaling pathway regulates mitochondrial morphology and function under pathophysiological conditions such as HF. Mitochondria change their shape and location via the activity of mitochondrial fission and fusion proteins. This mechanism is suggested as an important modulator for mitochondrial and cellular functions including bioenergetics, reactive oxygen species (ROS) generation, spatiotemporal dynamics of Ca2+ signaling, cell growth, and death in the mammalian cell- and tissue-specific manners. Recent reports show that a mitochondrial fission protein, dynamin-like/related protein 1 (DLP1/Drp1), is post-translationally modified via cell signaling pathways, which control its subcellular localization, stability, and activity in cardiomyocytes/heart. In this review, we summarize the possible molecular mechanisms for causing post-translational modifications (PTMs) of DLP1/Drp1 in cardiomyocytes, and further discuss how these PTMs of DLP1/Drp1 mediate abnormal mitochondrial morphology and mitochondrial dysfunction under adrenergic signaling activation that contributes to the development and progression of HF.

scholarly journals Gag3p, an Outer Membrane Protein Required for Fission of Mitochondrial Tubules

2000 ◽  
Vol 151 (2) ◽  
pp. 333-340 ◽  
Author(s):  
Peter Fekkes ◽  
Kelly A. Shepard ◽  
Michael P. Yaffe
Keyword(s):  
Outer Membrane ◽  
Mitochondrial Fission ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Gene Products ◽  
Mitochondrial Fragmentation ◽  
Gene Encoding ◽  
Peripheral Protein ◽  
And Function ◽  
Two Hybrid

Mitochondrial morphology and function depend on MGM1, a Saccharomyces cerevisiae gene encoding a dynamin-like protein of the mitochondrial outer membrane. Here, we show that mitochondrial fragmentation and mitochondrial genome loss caused by lesions in MGM1 are suppressed by three novel mutations, gag1, gag2, and gag3 (for glycerol-adapted growth). Cells with any of the gag mutations displayed aberrant mitochondrial morphology characterized by elongated, unbranched tubes and highly fenestrated structures. Additionally, each of the gag mutations prevented mitochondrial fragmentation caused by loss of the mitochondrial fusion factor, Fzo1p, or by treatment of cells with sodium azide. The gag1 mutation mapped to DNM1 that encodes a dynamin-related protein required for mitochondrial fission. GAG3 encodes a novel WD40-repeat protein previously found to interact with Dnm1p in a two-hybrid assay. Gag3p was localized to mitochondria where it was found to associate as a peripheral protein on the cytosolic face of the outer membrane. This association requires neither the DNM1 nor GAG2 gene products. However, the localization of Dnm1p to the mitochondrial outer membrane is substantially reduced by the gag2 mutation, but unaffected by loss of Gag3p. These results indicate that Gag3p plays a distinct role on the mitochondrial surface to mediate the fission of mitochondrial tubules.

scholarly journals Identification of Novel Therapeutic Targets for Polyglutamine Diseases That Target Mitochondrial Fragmentation

2021 ◽  
Vol 22 (24) ◽  
pp. 13447
Author(s):  
Annika Traa ◽  
Emily Machiela ◽  
Paige D. Rudich ◽  
Sonja K. Soo ◽  
Megan M. Senchuk ◽  
...  
Keyword(s):  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Cag Repeat ◽  
Mitochondrial Morphology ◽  
Polyglutamine Diseases ◽  
Mitochondrial Fragmentation ◽  
C Elegans ◽  
Beneficial Effects ◽  
Negative Side Effects ◽  
And Function

Huntington’s disease (HD) is one of at least nine polyglutamine diseases caused by a trinucleotide CAG repeat expansion, all of which lead to age-onset neurodegeneration. Mitochondrial dynamics and function are disrupted in HD and other polyglutamine diseases. While multiple studies have found beneficial effects from decreasing mitochondrial fragmentation in HD models by disrupting the mitochondrial fission protein DRP1, disrupting DRP1 can also have detrimental consequences in wild-type animals and HD models. In this work, we examine the effect of decreasing mitochondrial fragmentation in a neuronal C. elegans model of polyglutamine toxicity called Neur-67Q. We find that Neur-67Q worms exhibit mitochondrial fragmentation in GABAergic neurons and decreased mitochondrial function. Disruption of drp-1 eliminates differences in mitochondrial morphology and rescues deficits in both movement and longevity in Neur-67Q worms. In testing twenty-four RNA interference (RNAi) clones that decrease mitochondrial fragmentation, we identified eleven clones—each targeting a different gene—that increase movement and extend lifespan in Neur-67Q worms. Overall, we show that decreasing mitochondrial fragmentation may be an effective approach to treating polyglutamine diseases and we identify multiple novel genetic targets that circumvent the potential negative side effects of disrupting the primary mitochondrial fission gene drp-1.

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

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.

scholarly journals Identification of the Bok Interactome Using Proximity Labeling

2021 ◽  
Vol 9 ◽  
Author(s):  
Laura M. Szczesniak ◽  
Caden G. Bonzerato ◽  
Richard J. H. Wojcikiewicz
Keyword(s):  
Family Member ◽  
Transmembrane Domain ◽  
Mitochondrial Fission ◽  
Family Members ◽  
Potential Interaction ◽  
Mitochondrial Morphology ◽  
Mitochondrial Fragmentation ◽  
Knock Out ◽  
Inositol 1,4,5 Trisphosphate ◽  
Apoptosis Regulation

The function of the Bcl-2 family member Bok is currently enigmatic, with various disparate roles reported, including mediation of apoptosis, regulation of mitochondrial morphology, binding to inositol 1,4,5-trisphosphate receptors, and regulation of uridine metabolism. To better define the roles of Bok, we examined its interactome using TurboID-mediated proximity labeling in HeLa cells, in which Bok knock-out leads to mitochondrial fragmentation and Bok overexpression leads to apoptosis. Labeling with TurboID-Bok revealed that Bok was proximal to a wide array of proteins, particularly those involved in mitochondrial fission (e.g., Drp1), endoplasmic reticulum-plasma membrane junctions (e.g., Stim1), and surprisingly among the Bcl-2 family members, just Mcl-1. Comparison with TurboID-Mcl-1 and TurboID-Bak revealed that the three Bcl-2 family member interactomes were largely independent, but with some overlap that likely identifies key interactors. Interestingly, when overexpressed, Mcl-1 and Bok interact physically and functionally, in a manner that depends upon the transmembrane domain of Bok. Overall, this work shows that the Bok interactome is different from those of Mcl-1 and Bak, identifies novel proximities and potential interaction points for Bcl-2 family members, and suggests that Bok may regulate mitochondrial fission via Mcl-1 and Drp1.

scholarly journals Mitochondrial Dynamics Regulation in Skin Fibroblasts from Mitochondrial Disease Patients

Biomolecules ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 450 ◽  
Author(s):  
Takeshi Tokuyama ◽  
Asei Hirai ◽  
Isshin Shiiba ◽  
Naoki Ito ◽  
Keigo Matsuno ◽  
...  
Keyword(s):  
Mitochondrial Disease ◽  
Mitochondrial Myopathy ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Critical Role ◽  
Leigh Syndrome ◽  
Mitochondrial Morphology ◽  
Mitochondrial Fragmentation ◽  
Cellular Toxicity ◽  
Morphologic Changes

Mitochondria are highly dynamic organelles that constantly fuse, divide, and move, and their function is regulated and maintained by their morphologic changes. Mitochondrial disease (MD) comprises a group of disorders involving mitochondrial dysfunction. However, it is not clear whether changes in mitochondrial morphology are related to MD. In this study, we examined mitochondrial morphology in fibroblasts from patients with MD (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and Leigh syndrome). We observed that MD fibroblasts exhibited significant mitochondrial fragmentation by upregulation of Drp1, which is responsible for mitochondrial fission. Interestingly, the inhibition of mitochondrial fragmentation by Drp1 knockdown enhanced cellular toxicity and led to cell death in MD fibroblasts. These results suggest that mitochondrial fission plays a critical role in the attenuation of mitochondrial damage in MD fibroblasts.

scholarly journals Fzo1, a Protein Involved in Mitochondrial Fusion, Inhibits Apoptosis

2004 ◽  
Vol 279 (50) ◽  
pp. 52726-52734 ◽  
Author(s):  
Rie Sugioka ◽  
Shigeomi Shimizu ◽  
Yoshihide Tsujimoto
Keyword(s):  
Cell Death ◽  
Conformational Changes ◽  
Apoptotic Cell ◽  
Mitochondrial Fission ◽  
Apoptotic Cell Death ◽  
Mitochondrial Fusion ◽  
Mitochondrial Morphology ◽  
Human Homolog ◽  
Mitochondrial Fragmentation ◽  
Apoptotic Death

Mitochondrial morphology and physiology are regulated by the processes of fusion and fission. Some forms of apoptosis are reported to be associated with mitochondrial fragmentation. We showed that overexpression of Fzo1A/B (rat) proteins involved in mitochondrial fusion, or silencing of Dnm1 (rat)/Drp1 (human) (a mitochondrial fission protein), increased elongated mitochondria in healthy cells. After apoptotic stimulation, these interventions inhibited mitochondrial fragmentation and cell death, suggesting that a process involved in mitochondrial fusion/fission might play a role in the regulation of apoptosis. Consistently, silencing of Fzo1A/B or Mfn1/2 (a human homolog of Fzo1A/B) led to an increase of shorter mitochondria and enhanced apoptotic death. Overexpression of Fzo1 inhibited cytochromecrelease and activation of Bax/Bak, as assessed from conformational changes and oligomerization. Silencing of Mfn or Drp1 caused an increase or decrease of mitochondrial sensitivity to apoptotic stimulation, respectively. These results indicate that some of the proteins involved in mitochondrial fusion/fission modulate apoptotic cell death at the mitochondrial level.

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