scholarly journals A Human Dynamin-related Protein Controls the Distribution of Mitochondria

1998 ◽  
Vol 143 (2) ◽  
pp. 351-358 ◽  
Author(s):  
Elena Smirnova ◽  
Dixie-Lee Shurland ◽  
Sergey N. Ryazantsev ◽  
Alexander M. van der Bliek
Keyword(s):  
Environmental Changes ◽  
Large Mass ◽  
Mitochondrial Morphology ◽  
Related Protein ◽  
Wild Type ◽  
Gtpase Domain ◽  
Transfected Cells ◽  
Organelle Morphology ◽  
Endocytic Pathways ◽  
In Cells

Mitochondria exist as a dynamic tubular network with projections that move, break, and reseal in response to local environmental changes. We present evidence that a human dynamin-related protein (Drp1) is specifically required to establish this morphology. Drp1 is a GTPase with a domain structure similar to that of other dynamin family members. To identify the function of Drp1, we transiently transfected cells with mutant Drp1. A mutation in the GTPase domain caused profound alterations in mitochondrial morphology. The tubular projections normally present in wild-type cells were retracted into large perinuclear aggregates in cells expressing mutant Drp1. The morphology of other organelles was unaffected by mutant Drp1. There was also no effect of mutant Drp1 on the transport functions of the secretory and endocytic pathways. By EM, the mitochondrial aggregates found in cells that were transfected with mutant Drp1 appear as clusters of tubules rather than a large mass of coalescing membrane. We propose that Drp1 is important for distributing mitochondrial tubules throughout the cell. The function of this new dynamin-related protein in organelle morphology represents a novel role for a member of the dynamin family of proteins.

Abstract 16983: Inhibition of Dynamin-Related Protein 1 Accelerates Vascular Calcification in apoE-Deficient Mice through AKT Activation

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Maximillian Rogers ◽  
Natalia Maldonado ◽  
Tyler Fiats ◽  
Claudia Goettsch ◽  
Joshua D Hutcheson ◽  
...  
Keyword(s):  
Vascular Calcification ◽  
Atherogenic Diet ◽  
Strong Increase ◽  
Mitochondrial Morphology ◽  
Related Protein ◽  
Wild Type ◽  
Aortic Lesion ◽  
Calcified Lesion ◽  
Deficient Mice ◽  
Apoe Mouse

Background: Mitochondrial dysfunction has been implicated in the pathogenesis of cardiovascular disease. Dynamin-related protein 1 (DRP1) regulates mitochondrial function by driving membrane fission and allowing mitochondria to divide. How DRP1 acts in atherosclerosis, including the development of vascular calcification however remains unknown. Methods and Results: Aortic smooth muscle mitochondria from apoE-deficient mice (apoE-/-) exhibited a 47% increase in size compared to mitochondria from wild-type mice fed the same atherogenic diet for 18 weeks (N=103-129 mitochondria from 3 mice/group; p<0.05). In agreement with the observed changes in mitochondrial morphology, inhibitory phosphorylation of DRP1 on Ser637 was enriched in apoE-/- mouse aortas. DRP1 immunoreactivity increased around calcified areas of apoE-/- mouse aortic sections. Additionally, DRP1 mRNA was increased 1.8-fold in calcified over non-calcified areas (N=8; p<0.05). To determine the role of DRP1 inhibition on aortic lesion calcification, apoE-/- mice maintained on an atherogenic diet for 13 weeks (a point prior to calcified lesion development) were subsequently given the DRP1 inhibitor, MDIVI-1 (50mg/kg, i.p., once a week) for 5 more weeks. MDIVI-1 administration led to a 65% increase in calcified lesion area without altering lesion size (N=26 mice/group; p<0.05). A single injection of MDIVI-1 resulted in a 3-fold increase in the ratio of phospho-AKT to total pan-AKT along with a strong increase in Runx2 protein in the apoE-/- mouse aorta 6 hours post-injection. MDIVI-1 administration did not alter bone remolding as detected by micro-CT in wild type or apoE-/- mice (N=5 mice/group). Conclusion: We provide novel roles of the mitochondrial fission protein DRP1 in the vascular calcification process, and demonstrate that inhibition of DRP1 through administration of the DRP1 inhibitor MDIVI-1 in apoE-/- mice accelerates vascular calcification through the AKT/Runx2 pathway.

scholarly journals Aluminum fluoride stimulates surface protrusions in cells overexpressing the ARF6 GTPase.

1996 ◽  
Vol 134 (4) ◽  
pp. 935-947 ◽  
Author(s):  
H Radhakrishna ◽  
R D Klausner ◽  
J G Donaldson
Keyword(s):  
Plasma Membrane ◽  
Aluminum Fluoride ◽  
Wild Type ◽  
Lipoxygenase Pathway ◽  
Transfected Cells ◽  
Defective Mutant ◽  
Transferrin Uptake ◽  
Adp Ribosylation Factor ◽  
Stimulation Of ◽  
In Cells

To study the effector function of the ADP- ribosylation factor (ARF) 6 GTP-binding protein, we transfected HeLa cells with wild-type, epitope-tagged ARF6. Previously shown to indirectly activate the ARF1 GTPase, aluminum fluoride (AIF) treatment of ARF6-transfected cells resulted in a redistribution of both ARF6 and actin to discrete sites on the plasma membrane, which became increasingly protrusive over time. The effects of AIF were reversible, specific to cells transfected with wild-type ARF6, and resembled the cellular protrusions observed in cells expressing the GTPase defective mutant of ARF6. Importantly, the protrusions observed in cells transfected with ARF6 were distinct from the enhanced stress fibers and membrane ruffles observed in cells transfected with RhoA and Rac1, respectively. In cells forming protrusions, there was an apparent stimulation of macropinocytosis and membrane recycling within the protrusive structures. In contrast, no block in transferrin uptake or alteration of the distribution of clathrin AP-2 complexes was detected in these cells. The AIF-induced, ARF6- dependent formation of protrusive structures was blocked by cytochalasin D and inhibitors of the lipoxygenase pathway. These observations support a novel role for the ARF6 GTPase in modeling the plasma membrane and underlying cytoskeleton.

scholarly journals Mdm30 Is an F-Box Protein Required for Maintenance of Fusion-competent Mitochondria in Yeast

2003 ◽  
Vol 14 (6) ◽  
pp. 2303-2313 ◽  
Author(s):  
Stefan Fritz ◽  
Nadja Weinbach ◽  
Benedikt Westermann
Keyword(s):  
State Level ◽  
Mitochondrial Fusion ◽  
26S Proteasome ◽  
Mitochondrial Morphology ◽  
Wild Type ◽  
Heterologous Promoter ◽  
Gene Encoding ◽  
F Box Protein ◽  
And Function ◽  
In Cells

Mitochondrial fusion and fission play important roles for mitochondrial morphology and function. We identified Mdm30 as a novel component required for maintenance of fusion-competent mitochondria in yeast. The Mdm30 sequence contains an F-box motif that is commonly found in subunits of Skp1-Cdc53-F-box protein ubiquitin ligases. A fraction of Mdm30 is associated with mitochondria. Cells lacking Mdm30 contain highly aggregated or fragmented mitochondria instead of the branched tubular network seen in wild-type cells. Δmdm30 cells lose mitochondrial DNA at elevated temperature and fail to fuse mitochondria in zygotes at all temperatures. These defects are rescued by deletion of DNM1, a gene encoding a component of the mitochondrial division machinery. The protein level of Fzo1, a key component of the mitochondrial fusion machinery, is regulated by Mdm30. Elevated Fzo1 levels in cells lacking Mdm30 or in cells overexpressing Fzo1 from a heterologous promoter induce mitochondrial aggregation in a similar manner. Our results suggest that Mdm30 controls mitochondrial shape by regulating the steady-state level of Fzo1 and point to a connection of the ubiquitin/26S proteasome system and mitochondria.

scholarly journals Insulin activates p21Ras and guanine nucleotide releasing factor in cells expressing wild type and mutant insulin receptors.

1993 ◽  
Vol 268 (27) ◽  
pp. 19998-20001
Author(s):  
B Draznin ◽  
L Chang ◽  
J.W. Leitner ◽  
Y Takata ◽  
J.M. Olefsky
Keyword(s):  
Insulin Receptors ◽  
Guanine Nucleotide ◽  
Wild Type ◽  
Mutant Insulin ◽  
In Cells

scholarly journals SSADH Variants Increase Susceptibility of U87 Cells to Mitochondrial Pro-Oxidant Insult

2020 ◽  
Vol 21 (12) ◽  
pp. 4374
Author(s):  
Giovanna Menduti ◽  
Alessandra Vitaliti ◽  
Concetta Rosa Capo ◽  
Daniele Lettieri-Barbato ◽  
Katia Aquilano ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Mitochondrial Function ◽  
Antioxidant Defense ◽  
Mitochondrial Morphology ◽  
Common Snps ◽  
Protein Markers ◽  
Triple Mutant ◽  
Transfected Cells ◽  
Semialdehyde Dehydrogenase ◽  
Succinate Semialdehyde

Succinate semialdehyde dehydrogenase (SSADH) is a mitochondrial enzyme, encoded by ALDH5A1, mainly involved in γ-aminobutyric acid (GABA) catabolism and energy supply of neuronal cells, possibly contributing to antioxidant defense. This study aimed to further investigate the antioxidant role of SSADH, and to verify if common SNPs of ALDH5A1 may affect SSADH activity, stability, and mitochondrial function. In this study, we used U87 glioblastoma cells as they represent a glial cell line. These cells were transiently transfected with a cDNA construct simultaneously harboring three SNPs encoding for a triple mutant (TM) SSADH protein (p.G36R/p.H180Y/p.P182L) or with wild type (WT) cDNA. SSADH activity and protein level were measured. Cell viability, lipid peroxidation, mitochondrial morphology, membrane potential (ΔΨ), and protein markers of mitochondrial stress were evaluated upon Paraquat treatment, in TM and WT transfected cells. TM transfected cells show lower SSADH protein content and activity, fragmented mitochondria, higher levels of peroxidized lipids, and altered ΔΨ than WT transfected cells. Upon Paraquat treatment, TM cells show higher cell death, lipid peroxidation, 4-HNE protein adducts, and lower ΔΨ, than WT transfected cells. These results reinforce the hypothesis that SSADH contributes to cellular antioxidant defense; furthermore, common SNPs may produce unstable, less active SSADH, which could per se negatively affect mitochondrial function and, under oxidative stress conditions, fail to protect mitochondria.

scholarly journals RpoS-Dependent Stress Response and Exoenzyme Production in Vibrio vulnificus

2003 ◽  
Vol 69 (10) ◽  
pp. 6114-6120 ◽  
Author(s):  
A. Hülsmann ◽  
T. M. Rosche ◽  
I.-S. Kong ◽  
H. M. Hassan ◽  
D. M. Beam ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Stress Response ◽  
Mutant Strain ◽  
Environmental Changes ◽  
Vibrio Vulnificus ◽  
High Sensitivity ◽  
Striking Difference ◽  
Wild Type ◽  
Hydrolytic Activities ◽  
In The Wild

ABSTRACT Vibrio vulnificus is an estuarine bacterium capable of causing rapidly fatal infections through both ingestion and wound infection. Like other opportunistic pathogens, V. vulnificus must adapt to potentially stressful environmental changes while living freely in seawater, upon colonization of the oyster gut, and upon infection of such diverse hosts as humans and eels. In order to begin to understand the ability of V. vulnificus to respond to such stresses, we examined the role of the alternate sigma factor RpoS, which is important in stress response and virulence in many pathogens. An rpoS mutant of V. vulnificus strain C7184o was constructed by homologous recombination. The mutant strain exhibited a decreased ability to survive diverse environmental stresses, including exposure to hydrogen peroxide, hyperosmolarity, and acidic conditions. The most striking difference was a high sensitivity of the mutant to hydrogen peroxide. Albuminase, caseinase, and elastase activity were detected in the wild type but not in the mutant strain, and an additional two hydrolytic activities (collagenase and gelatinase) were reduced in the mutant strain compared to the wild type. Additionally, the motility of the rpoS mutant was severely diminished. Overall, these studies suggest that rpoS in V. vulnificus is important for adaptation to environmental changes and may have a role in virulence.

Overexpression of cysteine dioxygenase reduces intracellular cysteine and glutathione pools in HepG2/C3A cells

2007 ◽  
Vol 293 (1) ◽  
pp. E62-E69 ◽  
Author(s):  
John E. Dominy ◽  
Jesse Hwang ◽  
Martha H. Stipanuk
Keyword(s):  
Steady State ◽  
Experimental Evidence ◽  
Cysteine Dioxygenase ◽  
Wild Type ◽  
Hepatic Expression ◽  
Direct Experimental Evidence ◽  
Homeostatic Response ◽  
Catabolic Enzyme ◽  
In Cells

Cysteine levels are carefully regulated in mammals to balance metabolic needs against the potential for cytotoxicity. It has been postulated that one of the major regulators of intracellular cysteine levels in mammals is cysteine dioxygenase (CDO). Hepatic expression of this catabolic enzyme increases dramatically in response to increased cysteine availability and may therefore be part of a homeostatic response to shunt excess toxic cysteine to more benign metabolites such as sulfate or taurine. Direct experimental evidence, however, is lacking to support the hypothesis that CDO is capable of altering steady-state intracellular cysteine levels. In this study, we expressed either the wild-type (WT) or a catalytically inactivated mutant (H86A) isoform of CDO in HepG2/C3A cells (which do not express endogenous CDO protein) and cultured them in different concentrations of extracellular cysteine. WT CDO, but not H86A CDO, was capable of reducing intracellular cysteine levels in cells incubated in physiologically relevant concentrations of cysteine. WT CDO also decreased the glutathione pool and potentiated the toxicity of CdCl2. These results demonstrate that CDO is capable of altering intracellular cysteine levels as well as glutathione levels.

scholarly journals DNA tumor virus oncoproteins and retinoblastoma gene mutations share the ability to relieve the cell's requirement for cyclin D1 function in G1.

1994 ◽  
Vol 125 (3) ◽  
pp. 625-638 ◽  
Author(s):  
J Lukas ◽  
H Müller ◽  
J Bartkova ◽  
D Spitkovsky ◽  
A A Kjerulff ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Complex Formation ◽  
Cyclin D1 ◽  
Cell Lines ◽  
T Antigen ◽  
Regulatory Function ◽  
Retinoblastoma Gene ◽  
Checkpoint Control ◽  
Wild Type ◽  
In Cells

The retinoblastoma gene product (pRB) participates in the regulation of the cell division cycle through complex formation with numerous cellular regulatory proteins including the potentially oncogenic cyclin D1. Extending the current view of the emerging functional interplay between pRB and D-type cyclins, we now report that cyclin D1 expression is positively regulated by pRB. Cyclin D1 mRNA and protein is specifically downregulated in cells expressing SV40 large T antigen, adenovirus E1A, and papillomavirus E7/E6 oncogene products and this effect requires intact RB-binding, CR2 domain of E1A. Exceptionally low expression of cyclin D1 is also seen in genetically RB-deficient cell lines, in which ectopically expressed wild-type pRB results in specific induction of this G1 cyclin. At the functional level, antibody-mediated cyclin D1 knockout experiments demonstrate that the cyclin D1 protein, normally required for G1 progression, is dispensable for passage through the cell cycle in cell lines whose pRB is inactivated through complex formation with T antigen, E1A, or E7 oncoproteins as well as in cells which have suffered loss-of-function mutations of the RB gene. The requirement for cyclin D1 function is not regained upon experimental elevation of cyclin D1 expression in cells with mutant RB, while reintroduction of wild-type RB into RB-deficient cells leads to restoration of the cyclin D1 checkpoint. These results strongly suggest that pRB serves as a major target of cyclin D1 whose cell cycle regulatory function becomes dispensable in cells lacking functional RB. Based on available data including this study, we propose a model for an autoregulatory feedback loop mechanism that regulates both the expression of the cyclin D1 gene and the activity of pRB, thereby contributing to a G1 phase checkpoint control in cycling mammalian cells.

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