scholarly journals 3β-Hydroxysteroid-Δ24 Reductase Is a Hydrogen Peroxide Scavenger, Protecting Cells from Oxidative Stress-Induced Apoptosis

Endocrinology ◽  
2008 ◽  
Vol 149 (7) ◽  
pp. 3267-3273 ◽  
Author(s):  
Xiuli Lu ◽  
Fukushi Kambe ◽  
Xia Cao ◽  
Yasuko Kozaki ◽  
Takahide Kaji ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Endoplasmic Reticulum ◽  
Deletion Mutant ◽  
Terminal Deletion ◽  
Scavenging Activity ◽  
Ros Scavenging ◽  
Mouse Embryonic Fibroblasts ◽  
Embryonic Fibroblasts ◽  
Induced Apoptosis

3β-Hydroxysteroid-Δ24 reductase (DHCR24) is an endoplasmic reticulum-resident, multifunctional enzyme that possesses antiapoptotic and cholesterol-synthesizing activities. To clarify the molecular basis of the former activity, we investigated the effects of hydrogen peroxide (H2O2) on embryonic fibroblasts prepared from DHCR24-knockout mice (DHCR24−/− mouse embryonic fibroblasts). H2O2 exposure rapidly induced apoptosis, which was associated with sustained activation of apoptosis signal-regulating kinase-1 and stress-activated protein kinases, such as p38 MAPK and c-Jun N-terminal kinase. Complementation of the mouse embryonic fibroblasts by adenovirus expressing DHCR24 attenuated the H2O2-induced kinase activation and apoptosis. Concomitantly, intracellular generation of reactive oxygen species (ROS) in response to H2O2 was also diminished by the adenovirus, suggesting a ROS-scavenging activity of DHCR24. Such antiapoptotic effects of DHCR24 were duplicated in pheochromocytoma PC12 cells infected with adenovirus. In addition, it was found that DHCR24 exerted cytoprotective effects in the tunicamycin-induced endoplasmic reticulum stress by eliminating ROS. Finally, using in vitro-synthesized and purified proteins, DHCR24 and its C-terminal deletion mutant were found to exhibit high H2O2-scavenging activity, whereas the N-terminal deletion mutant lost such activity. These results demonstrate that DHCR24 can directly scavenge H2O2, thereby protecting cells from oxidative stress-induced apoptosis.

scholarly journals Caspase-2 Cleavage of BID Is a Critical Apoptotic Signal Downstream of Endoplasmic Reticulum Stress

2008 ◽  
Vol 28 (12) ◽  
pp. 3943-3951 ◽  
Author(s):  
John-Paul Upton ◽  
Kathryn Austgen ◽  
Mari Nishino ◽  
Kristen M. Coakley ◽  
Andrew Hagen ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Cell Loss ◽  
Mouse Embryonic Fibroblasts ◽  
Embryonic Fibroblasts ◽  
Proteolytic Activation ◽  
Caspase 2 ◽  
Induced Apoptosis ◽  
Mitochondrial Permeabilization ◽  
Apoptotic Signal

ABSTRACT The accumulation of misfolded proteins stresses the endoplasmic reticulum (ER) and triggers cell death through activation of the multidomain proapoptotic BCL-2 proteins BAX and BAK at the outer mitochondrial membrane. The signaling events that connect ER stress with the mitochondrial apoptotic machinery remain unclear, despite evidence that deregulation of this pathway contributes to cell loss in many human degenerative diseases. In order to “trap” and identify the apoptotic signals upstream of mitochondrial permeabilization, we challenged Bax − / − Bak − / − mouse embryonic fibroblasts with pharmacological inducers of ER stress. We found that ER stress induces proteolytic activation of the BH3-only protein BID as a critical apoptotic switch. Moreover, we identified caspase-2 as the premitochondrial protease that cleaves BID in response to ER stress and showed that resistance to ER stress-induced apoptosis can be conferred by inhibiting caspase-2 activity. Our work defines a novel signaling pathway that couples the ER and mitochondria and establishes a principal apoptotic effector downstream of ER stress.

scholarly journals Intracellular Sources of ROS/H2O2 in Health and Neurodegeneration: Spotlight on Endoplasmic Reticulum

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 233
Author(s):  
Tasuku Konno ◽  
Eduardo Pinho Melo ◽  
Joseph E. Chambers ◽  
Edward Avezov
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Hydrogen Peroxide ◽  
Endoplasmic Reticulum ◽  
Neurodegenerative Diseases ◽  
Antioxidative Enzymes ◽  
Redox Reactions ◽  
Ros Production ◽  
Oxygen Species ◽  
Specific Target

Reactive oxygen species (ROS) are produced continuously throughout the cell as products of various redox reactions. Yet these products function as important signal messengers, acting through oxidation of specific target factors. Whilst excess ROS production has the potential to induce oxidative stress, physiological roles of ROS are supported by a spatiotemporal equilibrium between ROS producers and scavengers such as antioxidative enzymes. In the endoplasmic reticulum (ER), hydrogen peroxide (H2O2), a non-radical ROS, is produced through the process of oxidative folding. Utilisation and dysregulation of H2O2, in particular that generated in the ER, affects not only cellular homeostasis but also the longevity of organisms. ROS dysregulation has been implicated in various pathologies including dementia and other neurodegenerative diseases, sanctioning a field of research that strives to better understand cell-intrinsic ROS production. Here we review the organelle-specific ROS-generating and consuming pathways, providing evidence that the ER is a major contributing source of potentially pathologic ROS.

PERK mediates oxidative stress and adipogenesis in Graves’ orbitopathy pathogenesis

2021 ◽  
Author(s):  
JaeSang Ko ◽  
Ji-Young Kim ◽  
Min Kyung Chae ◽  
Eun Jig Lee ◽  
Jin Sook Yoon
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Er Stress ◽  
Adipogenic Differentiation ◽  
Ros Generation ◽  
Mrna Levels ◽  
Graves Orbitopathy ◽  
Orbital Fibroblasts

We examined endoplasmic reticulum (ER) stress-related gene expression in orbital tissues from patients with Graves’ orbitopathy (GO) and the effects of silencing protein kinase RNA-like endoplasmic reticulum kinase (PERK) in primary orbital fibroblast cultures to demonstrate the therapeutic potential of PERK-modulating agents in GO management. The expression of ER stress related genes in orbital tissue harvested from individuals with or without GO was studied using real-time polymerase chain reaction. The role of PERK in GO pathogenesis was examined through small-interfering RNA (siRNA)-mediated silencing in cultured primary orbital fibroblasts. Intracellular reactive oxygen species (ROS) levels induced in response to cigarette smoke extract (CSE) or hydrogen peroxide were measured using 5-(and 6)-carboxy-20,70-dichlorodihydrofluorescein diacetate staining and flow cytometry. Cells were stained with Oil Red O, and adipogenesis-related transcription factor expression was evaluated through western blotting after adipogenic differentiation. PERK, activating transcription factor 4 (ATF4), and CCAAT-enhancer-binding protein (C/EBP)-homologous protein(CHOP)mRNA levels were significantly higher in GO orbital tissues than in non-GO orbital tissues. PERK silencing inhibited CSE- or hydrogen peroxide-induced ROS generation. After adipogenic differentiation, GO orbital fibroblasts revealed decreased lipid droplets and downregulation of C/EBPα, C/EBPβ, and peroxisome proliferator-activator gamma (PPARγ) in PERK siRNA-transfected cells. The orbital tissues of patients with GO were exposed to chronic ER stress and subsequently exhibited enhanced unfolded protein response (especially through the PERK pathway). PERK silencing reduced oxidative stress and adipogenesis in GO orbital fibroblasts in vitro. Our results imply that PERK-modulating agents can potentially be used to manage GO.

scholarly journals Activation of endoplasmic reticulum stress mediates oxidative stress–induced apoptosis of granulosa cells in ovaries affected by endometrioma

2019 ◽  
Vol 26 (1) ◽  
pp. 40-52 ◽  
Author(s):  
Chisato Kunitomi ◽  
Miyuki Harada ◽  
Nozomi Takahashi ◽  
Jerilee M K Azhary ◽  
Akari Kusamoto ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Granulosa Cells ◽  
Ovarian Function ◽  
Stress Sensor ◽  
Local Factor ◽  
High Oxidative Stress ◽  
Induced Apoptosis ◽  
Sensor Proteins

Abstract Endometriosis exerts detrimental effects on ovarian physiology and compromises follicular health. Granulosa cells from patients with endometriosis are characterized by increased apoptosis, as well as high oxidative stress. Endoplasmic reticulum (ER) stress, a local factor closely associated with oxidative stress, has emerged as a critical regulator of ovarian function. We hypothesized that ER stress is activated by high oxidative stress in granulosa cells in ovaries with endometrioma and that this mediates oxidative stress–induced apoptosis. Human granulosa-lutein cells (GLCs) from patients with endometrioma expressed high levels of mRNAs associated with the unfolded protein response (UPR). In addition, the levels of phosphorylated ER stress sensor proteins, inositol-requiring enzyme 1 (IRE1) and double-stranded RNA-activated protein kinase-like ER kinase (PERK), were elevated in granulosa cells from patients with endometrioma. Given that ER stress results in phosphorylation of ER stress sensor proteins and induces UPR factors, these findings indicate that these cells were under ER stress. H2O2, an inducer of oxidative stress, increased expression of UPR-associated mRNAs in cultured human GLCs, and this effect was abrogated by pretreatment with tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor in clinical use. Treatment with H2O2 increased apoptosis and the activity of the pro-apoptotic factors caspase-8 and caspase-3, both of which were attenuated by TUDCA. Our findings suggest that activated ER stress induced by high oxidative stress in granulosa cells in ovaries with endometrioma mediates apoptosis of these cells, leading to ovarian dysfunction in patients with endometriosis.

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