scholarly journals Importance of the bioenergetic reserve capacity in response to cardiomyocyte stress induced by 4-hydroxynonenal

2009 ◽  
Vol 424 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Bradford G. Hill ◽  
Brian P. Dranka ◽  
Luyun Zou ◽  
John C. Chatham ◽  
Victor M. Darley-Usmar

Mitochondria play a critical role in mediating the cellular response to oxidants formed during acute and chronic cardiac dysfunction. It is widely assumed that, as cells are subjected to stress, mitochondria are capable of drawing upon a ‘reserve capacity’ which is available to serve the increased energy demands for maintenance of organ function, cellular repair or detoxification of reactive species. This hypothesis further implies that impairment or depletion of this putative reserve capacity ultimately leads to excessive protein damage and cell death. However, it has been difficult to fully evaluate this hypothesis since much of our information about the response of the mitochondrion to oxidative stress derives from studies on mitochondria isolated from their cellular context. Therefore the goal of the present study was to determine whether ‘bioenergetic reserve capacity’ does indeed exist in the intact myocyte and whether it is utilized in response to stress induced by the pathologically relevant reactive lipid species HNE (4-hydroxynonenal). We found that intact rat neonatal ventricular myocytes exhibit a substantial bioenergetic reserve capacity under basal conditions; however, on exposure to pathologically relevant concentrations of HNE, oxygen consumption was increased until this reserve capacity was depleted. Exhaustion of the reserve capacity by HNE treatment resulted in inhibition of respiration concomitant with protein modification and cell death. These data suggest that oxidized lipids could contribute to myocyte injury by decreasing the bioenergetic reserve capacity. Furthermore, these studies demonstrate the utility of measuring the bioenergetic reserve capacity for assessing or predicting the response of cells to stress.

2020 ◽  
Vol 28 (1) ◽  
pp. 401-418
Author(s):  
Han Qiao ◽  
Tianqing Jiang ◽  
Peiqiang Mu ◽  
Xiaoxuan Chen ◽  
Xianhui Wen ◽  
...  

AbstractDouble-stranded RNA (dsRNA)-dependent protein kinase R (PKR) activation via autophosphorylation is the central cellular response to stress that promotes cell death or apoptosis. However, the key factors and mechanisms behind the simultaneous activation of pro-survival signaling pathways remain unknown. We have discovered a novel regulatory mechanism for the maintenance of cellular homeostasis that relies on the phosphorylation interplay between sphingosine kinase 1 (SPHK1) and PKR during exogenous stress. We identified SPHK1 as a previously unrecognized PKR substrate. Phosphorylated SPHK1, a central kinase, mediates the activation of PKR-induced pro-survival pathways by the S1P/S1PR1/MAPKs/IKKα signal axis, and antagonizes PKR-mediated endoplasmic reticulum (ER) stress signal transduction under stress conditions. Otherwise, phosphorylated SPHK1 also acts as the negative feedback factor, preferentially binding to the latent form of PKR at the C-terminal kinase motif, inhibiting the homodimerization of PKR, suppressing PKR autophosphorylation, and reducing the signaling strength for cell death and apoptosis. Our results suggest that the balance of the activation levels between PKR and SPHK1, a probable hallmark of homeostasis maintenance, determines cell fate during cellular stress response.


2011 ◽  
Vol 39 (5) ◽  
pp. 1466-1470 ◽  
Author(s):  
Belém Sampaio-Marques ◽  
Carolina Felgueiras ◽  
Alexandra Silva ◽  
Fernando Rodrigues ◽  
Paula Ludovico

Autophagy, a highly conserved proteolytic mechanism of quality control, is essential for the maintenance of metabolic and cellular homoeostasis and for an efficient cellular response to stress. Autophagy declines with aging and is believed to contribute to different aspects of the aging phenotype. The nutrient-sensing pathways PKA (protein kinase A), Sch9 and TOR (target of rapamycin), involved in the regulation of yeast lifespan, also converge on a common targeted process: autophagy. The molecular mechanisms underlying the regulation of autophagy and aging by these signalling pathways in yeast, with special attention to the TOR pathway, are discussed in the present paper. The question of whether or not autophagy could contribute to yeast cell death occurring during CLS (chronological lifespan) is discussed in the light of our findings obtained after autophagy activation promoted by proteotoxic stress. Autophagy progressively increases in cells expressing the aggregation-prone protein α-synuclein and seems to participate in the early cell death and shortening of CLS under these conditions, highlighting that autophagic activity should be maintained below physiological levels to exert its promising anti-aging effects.


2009 ◽  
Vol 185 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Debrah M. Thompson ◽  
Roy Parker

The cellular response to stress conditions involves a decision between survival or cell death when damage is severe. A conserved stress response in eukaryotes involves endonucleolytic cleavage of transfer RNAs (tRNAs). The mechanism and significance of such tRNA cleavage is unknown. We show that in yeast, tRNAs are cleaved by the RNase T2 family member Rny1p, which is released from the vacuole into the cytosol during oxidative stress. Rny1p modulates yeast cell survival during oxidative stress independently of its catalytic ability. This suggests that upon release to the cytosol, Rny1p promotes cell death by direct interactions with downstream components. Thus, detection of Rny1p, and possibly its orthologues, in the cytosol may be a conserved mechanism for assessing cellular damage and determining cell survival, analogous to the role of cytochrome c as a marker for mitochondrial damage.


Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 757
Author(s):  
Verena Warnsmann ◽  
Lisa-Marie Marschall ◽  
Heinz D. Osiewacz

Mitochondrial F1Fo-ATP-synthase dimers play a critical role in shaping and maintenance of mitochondrial ultrastructure. Previous studies have revealed that ablation of the F1Fo-ATP-synthase assembly factor PaATPE of the ascomycete Podospora anserina strongly affects cristae formation, increases hydrogen peroxide levels, impairs mitochondrial function and leads to premature cell death. In the present study, we investigated the underlying mechanistic basis. Compared to the wild type, we observed a slight increase in non-selective and a pronounced increase in mitophagy, the selective vacuolar degradation of mitochondria. This effect depends on the availability of functional cyclophilin D (PaCYPD), the regulator of the mitochondrial permeability transition pore (mPTP). Simultaneous deletion of PaAtpe and PaAtg1, encoding a key component of the autophagy machinery or of PaCypD, led to a reduction of mitophagy and a partial restoration of the wild-type specific lifespan. The same effect was observed in the PaAtpe deletion strain after inhibition of PaCYPD by its specific inhibitor, cyclosporin A. Overall, our data identify autophagy-dependent cell death (ADCD) as part of the cellular response to impaired F1Fo-ATP-synthase dimerization, and emphasize the crucial role of functional mitochondria in aging.


Author(s):  
Agata Kodroń ◽  
Parvana Hajieva ◽  
Agata Kulicka ◽  
Bohdan Paterczyk ◽  
Elona Jankauskaite ◽  
...  

Mitochondria are key players in cell death through the activation of the intrinsic apoptosis pathway. BNIP3 and BNIP3L/Nix are outer mitochondrial membrane bifunctional proteins which because of containing both BH3 and LIR domains play a role in cellular response to stress by regulation of apoptosis and selective autophagy. Leber’s Hereditary Optic Neuropathy (LHON) is the most common mitochondrial disease in adults, characterized by painless loss of vision caused by atrophy of the optic nerve. The disease in over 90% of cases is caused by one of three mutations in the mitochondrial genome: 11778G>A, 3460G>A or 14484T>C. The pathogenic processes leading to optic nerve degeneration are largely unknown, however, the most common explanation is that mtDNA mutations increase the apoptosis level in this tissue. Here we present the results of analysis of BNIP3 and BNIP3L/Nix proteins in cells harboring a combination of the 11778G>A and the 3460G>A LHON mutations. Experiments performed on cybrids revealed that BNIP3 protein level is decreased in LHON cells compared to controls. CCCP treatment resulted in apoptosis induction only in control cells. Moreover, we also noticed reduced level of autophagy in LHON cybrids. The presented results suggest that in cells carrying LHON mutations expression of proteins involved in regulation of apoptosis and autophagy is decreased what in turn may disturb cell death pathways in those cells and affect cellular response to stress.  


2008 ◽  
Vol 36 (3) ◽  
pp. 445-448 ◽  
Author(s):  
Terence A. Agbor ◽  
Cormac T. Taylor

Post-translational modification is a critical event in the dynamic regulation of protein stability, location, structure, function, activity and interaction with other proteins and as such plays an important role in organism complexity. Over the last 10 years, the extensive and critical role of one such protein modification by SUMO (small ubiquitin-related modifier) has become apparent. The focus of this mini-review will be on recent reports of a possible functional role for the SUMO pathway in the adaptive cellular response to metabolic challenge, such as oxygen deprivation (hypoxia). Here, we will briefly review the evolving evidence for this pathway in the regulation of a number of metabolic regulators and discuss a possible role for SUMOylation in the regulation of basic metabolic function.


2006 ◽  
Vol 17 (2) ◽  
pp. 770-778 ◽  
Author(s):  
Nica M. Borradaile ◽  
Kimberly K. Buhman ◽  
Laura L. Listenberger ◽  
Carolyn J. Magee ◽  
Emiko T.A. Morimoto ◽  
...  

The deleterious consequences of fatty acid (FA) and neutral lipid accumulation in nonadipose tissues, such as the heart, contribute to the pathogenesis of type 2 diabetes. To elucidate mechanisms of FA-induced cell death, or lipotoxicity, we generated Chinese hamster ovary (CHO) cell mutants resistant to palmitate-induced death and isolated a clone with disruption of eukaryotic elongation factor (eEF) 1A-1. eEF1A-1 involvement in lipotoxicity was confirmed in H9c2 cardiomyoblasts, in which small interfering RNA-mediated knockdown also conferred palmitate resistance. In wild-type CHO and H9c2 cells, palmitate increased reactive oxygen species and induced endoplasmic reticulum (ER) stress, changes accompanied by increased eEF1A-1 expression. Disruption of eEF1A-1 expression rendered these cells resistant to hydrogen peroxide- and ER stress-induced death, indicating that eEF1A-1 plays a critical role in the cell death response to these stressors downstream of lipid overload. Disruption of eEF1A-1 also resulted in actin cytoskeleton defects under basal conditions and in response to palmitate, suggesting that eEF1A-1 mediates lipotoxic cell death, secondary to oxidative and ER stress, by regulating cytoskeletal changes critical for this process. Furthermore, our observations of oxidative stress, ER stress, and induction of eEF1A-1 expression in a mouse model of lipotoxic cardiomyopathy implicate this cellular response in the pathophysiology of metabolic disease.


2019 ◽  
Vol 24 (40) ◽  
pp. 4726-4741 ◽  
Author(s):  
Orathai Tangvarasittichai ◽  
Surapon Tangvarasittichai

Background: Oxidative stress is caused by free radicals or oxidant productions, including lipid peroxidation, protein modification, DNA damage and apoptosis or cell death and results in cellular degeneration and neurodegeneration from damage to macromolecules. Results: Accumulation of the DNA damage (8HOdG) products and the end products of LPO (including aldehyde, diene, triene conjugates and Schiff’s bases) were noted in the research studies. Significantly higher levels of these products in comparison with the controls were observed. Oxidative stress induced changes to ocular cells and tissues. Typical changes include ECM accumulation, cell dysfunction, cell death, advanced senescence, disarrangement or rearrangement of the cytoskeleton and released inflammatory cytokines. It is involved in ocular diseases, including keratoconus, Fuchs endothelial corneal dystrophy, and granular corneal dystrophy type 2, cataract, age-related macular degeneration, primary open-angle glaucoma, retinal light damage, and retinopathy of prematurity. These ocular diseases are the cause of irreversible blindness worldwide. Conclusions: Oxidative stress, inflammation and autophagy are implicated in biochemical and morphological changes in these ocular tissues. The development of therapy is a major target for the management care of these ocular diseases.


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