scholarly journals Destroy and Exploit: Catalyzed Removal of Hydroperoxides from the Endoplasmic Reticulum

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Thomas Ramming ◽  
Christian Appenzeller-Herzog
Keyword(s):  
Hydrogen Peroxide ◽  
Endoplasmic Reticulum ◽  
Second Messengers ◽  
Eukaryotic Cells ◽  
Lipid Hydroperoxides ◽  
Common Theme ◽  
Oxidative Protein Folding ◽  
Glutathione Peroxidases

Peroxidases are enzymes that reduce hydroperoxide substrates. In many cases, hydroperoxide reduction is coupled to the formation of a disulfide bond, which is transferred onto specific acceptor molecules, the so-called reducing substrates. As such, peroxidases control the spatiotemporal distribution of diffusible second messengers such as hydrogen peroxide (H2O2) and generate new disulfides. Members of two families of peroxidases, peroxiredoxins (Prxs) and glutathione peroxidases (GPxs), reside in different subcellular compartments or are secreted from cells. This review discusses the properties and physiological roles of PrxIV, GPx7, and GPx8 in the endoplasmic reticulum (ER) of higher eukaryotic cells where H2O2and—possibly—lipid hydroperoxides are regularly produced. Different peroxide sources and reducing substrates for ER peroxidases are critically evaluated. Peroxidase-catalyzed detoxification of hydroperoxides coupled to the productive use of disulfides, for instance, in the ER-associated process of oxidative protein folding, appears to emerge as a common theme. Nonetheless,in vitroandin vivostudies have demonstrated that individual peroxidases serve specific, nonoverlapping roles in ER physiology.

scholarly journals The Molecular Chaperone Calnexin Interacts with the NSP4 Enterotoxin of Rotavirus In Vivo and In Vitro

1998 ◽  
Vol 72 (11) ◽  
pp. 8705-8709 ◽  
Author(s):  
Ali Mirazimi ◽  
Mikael Nilsson ◽  
Lennart Svensson
Keyword(s):  
Endoplasmic Reticulum ◽  
Molecular Chaperone ◽  
Secretory Pathway ◽  
Infectious Virus ◽  
Time Dependent ◽  
In Vitro Translation ◽  
Eukaryotic Cells ◽  
Dependent Manner

ABSTRACT Calnexin is an endoplasmic reticulum (ER)-associated molecular chaperone proposed to promote folding and assembly of glycoproteins that traverse the secretory pathway in eukaryotic cells. In this study we examined if calnexin interacts with the ER-associated luminal (VP7) and transmembrane (NSP4) proteins of rotavirus. Only glycosylated NSP4 interacted with calnexin and did so in a time-dependent manner (half-life, 20 min). In vitro translation experiments programmed with gene 10 of rhesus rotavirus confirmed that calnexin recognizes only glycosylated NSP4. Castanospermine (a glucosidase I and II inhibitor) experiments established that calnexin associates only with partly deglucosylated (di- or monoglucosylated) NSP4. Furthermore, enzymatic removal of the remaining glucose residues on the N-linked glycan units was essential to disengage the NSP4-calnexin complex. Novel experiments with castanospermine revealed that glucose trimming and the calnexin-NSP4 interaction were not critical for the assembly of infectious virus.

The Hierarchic Order of Intermediate Filament Structure and Assembly

1985 ◽  
Vol 43 ◽  
pp. 722-725
Author(s):  
U. Aebi ◽  
E.C. Glavaris ◽  
R. Eichner
Keyword(s):  
Tissue Specificity ◽  
Structural Model ◽  
Eukaryotic Cells ◽  
Cdna Sequencing ◽  
Filament Structure ◽  
Keratin Filaments ◽  
Isoelectric Points ◽  
Immunological Crossreactivity

Five different classes of intermediate-sized filaments (IFs) have been identified in differentiated eukaryotic cells: vimentin in mesenchymal cells, desmin in muscle cells, neurofilaments in nerve cells, glial filaments in glial cells and keratin filaments in epithelial cells. Despite their tissue specificity, all IFs share several common attributes, including immunological crossreactivity, similar morphology (e.g. about 10 nm diameter - hence ‘10-nm filaments’) and the ability to reassemble in vitro from denatured subunits into filaments virtually indistinguishable from those observed in vivo. Further more, despite their proteinchemical heterogeneity (their MWs range from 40 kDa to 200 kDa and their isoelectric points from about 5 to 8), protein and cDNA sequencing of several IF polypeptides (for refs, see 1,2) have provided the framework for a common structural model of all IF subunits.

scholarly journals Dehydrodiisoeugenol inhibits colorectal cancer growth by endoplasmic reticulum stress-induced autophagic pathways

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Changhong Li ◽  
Kui Zhang ◽  
Guangzhao Pan ◽  
Haoyan Ji ◽  
Chongyang Li ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Endoplasmic Reticulum ◽  
Cell Growth ◽  
Er Stress ◽  
Cancer Cells ◽  
Tumor Xenograft ◽  
Anticancer Activities ◽  
Colorectal Cancer Cells

Abstract Background Dehydrodiisoeugenol (DEH), a novel lignan component extracted from nutmeg, which is the seed of Myristica fragrans Houtt, displays noticeable anti-inflammatory and anti-allergic effects in digestive system diseases. However, the mechanism of its anticancer activity in gastrointestinal cancer remains to be investigated. Methods In this study, the anticancer effect of DEH on human colorectal cancer and its underlying mechanism were evaluated. Assays including MTT, EdU, Plate clone formation, Soft agar, Flow cytometry, Electron microscopy, Immunofluorescence and Western blotting were used in vitro. The CDX and PDX tumor xenograft models were used in vivo. Results Our findings indicated that treatment with DEH arrested the cell cycle of colorectal cancer cells at the G1/S phase, leading to significant inhibition in cell growth. Moreover, DEH induced strong cellular autophagy, which could be inhibited through autophagic inhibitors, with a rction in the DEH-induced inhibition of cell growth in colorectal cancer cells. Further analysis indicated that DEH also induced endoplasmic reticulum (ER) stress and subsequently stimulated autophagy through the activation of PERK/eIF2α and IRE1α/XBP-1 s/CHOP pathways. Knockdown of PERK or IRE1α significantly decreased DEH-induced autophagy and retrieved cell viability in cells treated with DEH. Furthermore, DEH also exhibited significant anticancer activities in the CDX- and PDX-models. Conclusions Collectively, our studies strongly suggest that DEH might be a potential anticancer agent against colorectal cancer by activating ER stress-induced inhibition of autophagy.

A novel colorimetric and near-infrared fluorescent probe for hydrogen peroxide imaging in vitro and in vivo

RSC Advances ◽  
2015 ◽  
Vol 5 (104) ◽  
pp. 85957-85963 ◽  
Author(s):  
Peng Wang ◽  
Ke Wang ◽  
Dan Chen ◽  
Yibo Mao ◽  
Yueqing Gu
Keyword(s):  
Hydrogen Peroxide ◽  
Fluorescent Probe ◽  
Near Infrared

A novel NIR fluorescent probe (DCM-B2) based on dicyanomethylene-4H-pyran was synthesized for the detection of H2O2.

scholarly journals Overexpression of SERCA2a Alleviates Cardiac Microvascular Ischemic Injury by Suppressing Mfn2-Mediated ER/Mitochondrial Calcium Tethering

2021 ◽  
Vol 9 ◽  
Author(s):  
Feng Tian ◽  
Ying Zhang
Keyword(s):  
Endoplasmic Reticulum ◽  
Infarct Size ◽  
Myocardial Infarct ◽  
Ischemic Injury ◽  
Calcium Overload ◽  
Mitochondrial Calcium ◽  
Myocardial Infarct Size ◽  
Hypoxic Injury

Our previous research has shown that type-2a Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) undergoes posttranscriptional oxidative modifications in cardiac microvascular endothelial cells (CMECs) in the context of excessive cardiac oxidative injury. However, whether SERCA2a inactivity induces cytosolic Ca2+ imbalance in mitochondrial homeostasis is far from clear. Mitofusin2 (Mfn2) is well known as an important protein involved in endoplasmic reticulum (ER)/mitochondrial Ca2+ tethering and the regulation of mitochondrial quality. Therefore, the aim of our study was to elucidate the specific mechanism of SERCA2a-mediated Ca2+ overload in the mitochondria via Mfn2 tethering and the survival rate of the heart under conditions of cardiac microvascular ischemic injury. In vitro, CMECs extracted from mice were subjected to 6 h of hypoxic injury to mimic ischemic heart injury. C57-WT and Mfn2KO mice were subjected to a 1 h ischemia procedure via ligation of the left anterior descending branch to establish an in vivo cardiac ischemic injury model. TTC staining, immunohistochemistry and echocardiography were used to assess the myocardial infarct size, microvascular damage, and heart function. In vitro, ischemic injury induced irreversible oxidative modification of SERCA2a, including sulfonylation at cysteine 674 and nitration at tyrosine 294/295, and inactivation of SERCA2a, which initiated calcium overload. In addition, ischemic injury-triggered [Ca2+]c overload and subsequent [Ca2+]m overload led to mPTP opening and ΔΨm dissipation compared with the control. Furthermore, ablation of Mfn2 alleviated SERCA2a-induced mitochondrial calcium overload and subsequent mito-apoptosis in the context of CMEC hypoxic injury. In vivo, compared with that in wild-type mice, the myocardial infarct size in Mfn2KO mice was significantly decreased. In addition, the findings revealed that Mfn2KO mice had better heart contractile function, decreased myocardial infarction indicators, and improved mitochondrial morphology. Taken together, the results of our study suggested that SERCA2a-dependent [Ca2+]c overload led to mitochondrial dysfunction and activation of Mfn2-mediated [Ca2+]m overload. Overexpression of SERCA2a or ablation of Mfn2 expression mitigated mitochondrial morphological and functional damage by modifying the SERCA2a/Ca2+-Mfn2 pathway. Overall, these pathways are promising therapeutic targets for acute cardiac microvascular ischemic injury.

scholarly journals Hexarelin exerts neuroprotective and antioxidant effects against hydrogen peroxide-induced toxicity through the modulation of MAPK and PI3K/Akt patways in Neuro-2A cells

2020 ◽  
Author(s):  
Ramona Meanti ◽  
Laura Rizzi ◽  
Elena Bresciani ◽  
Laura Molteni ◽  
Vittorio Locatelli ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Apoptotic Cell ◽  
Neuroblastoma Cell ◽  
Neuroblastoma Cell Line ◽  
Inhibitory Influence ◽  
No Production ◽  
Mrna Levels

AbstractHexarelin, a synthetic hexapeptide, protects cardiac and skeletal muscles by inhibiting apoptosis, both in vitro and in vivo. Moreover, evidence suggests that hexarelin could have important neuroprotective bioactivity.Oxidative stress and the generation of free radicals has been implicated in the etiologies of several neurodegenerative diseases, including amyotrophic lateral sclerosis, Parkinson’s disease, Alzheimer’s disease, Huntington’s disease and multiple sclerosis. In addition to direct oxidative stress, exogenous hydrogen peroxide (H2O2) can penetrate biological membranes and enhance the formation of other reactive oxygen species.The aim of this study was to examine the inhibitory influence of hexarelin on H2O2-induced apoptosis in Neuro-2A cells, a mouse neuroblastoma cell line. Our results indicate that H2O2 reduced the viability of Neuro-2A cells in a dose-related fashion. Furthermore, H2O2 induced significant changes in the morphology of Neuro-2A cells, reflected in the formation of apoptotic cell bodies, and an increase of nitric oxide (NO) production. Hexarelin effectively antagonized H2O2 oxidative damage to Neuro-2A cells as indicated by improved cell viability, normal morphology and reduced nitrite (NO2−) release. Hexarelin treatment of Neuro-2A cells also reduced mRNA levels of caspases−3 and −7 and those of the pro-apoptotic molecule Bax; by contrast, hexarelin treatment increased anti-apoptotic Bcl-2 mRNA levels. Hexarelin also reduced MAPKs phosphorylation induced by H2O2 and concurrently increased p-Akt protein expression.In conclusion, our results identify several neuroprotective and anti-apoptotic effects of hexarelin. These properties suggest that further investigation of hexarelin as a neuroprotective agent in an investigational and therapeutic context are merited.

scholarly journals Biochanin A Alleviates Cerebral Ischemia/Reperfusion Injury by Suppressing Endoplasmic Reticulum Stress-Induced Apoptosis and p38MAPK Signaling Pathway In Vivo and In Vitro

2021 ◽  
Vol 12 ◽  
Author(s):  
Min-min Guo ◽  
Sheng-biao Qu ◽  
Hui-ling Lu ◽  
Wen-bo Wang ◽  
Mu-Liang He ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
P38 Mapk ◽  
Ischemia Reperfusion ◽  
Biochanin A ◽  
Neurological Deficits ◽  
Mapk Phosphorylation ◽  
Cerebral Ischemia Reperfusion

We have previously shown that biochanin A exhibits neuroprotective properties in the context of cerebral ischemia/reperfusion (I/R) injury. The mechanistic basis for such properties, however, remains poorly understood. This study was therefore designed to explore the manner whereby biochanin A controls endoplasmic reticulum (ER) stress, apoptosis, and inflammation within fetal rat primary cortical neurons in response to oxygen-glucose deprivation/reoxygenation (OGD/R) injury, and in a rat model of middle cerebral artery occlusion and reperfusion (MCAO/R) injury. For the OGD/R in vitro model system, cells were evaluated after a 2 h OGD following a 24 h reoxygenation period, whereas in vivo neurological deficits were evaluated following 2 h of ischemia and 24 h of reperfusion. The expression of proteins associated with apoptosis, ER stress (ERS), and p38 MAPK phosphorylation was evaluated in these samples. Rats treated with biochanin A exhibited reduced neurological deficits relative to control rats following MCAO/R injury. Additionally, GRP78 and CHOP levels rose following I/R modeling both in vitro and in vivo, whereas biochanin A treatment was associated with reductions in CHOP levels but further increases in GRP78 levels. In addition, OGD/R or MCAO/R were associated with markedly enhanced p38 MAPK phosphorylation that was alleviated by biochanin A treatment. Similarly, OGD/R or MCAO/R injury resulted in increases in caspase-3, caspase-12, and Bax levels as well as decreases in Bcl-2 levels, whereas biochanin A treatment was sufficient to reverse these phenotypes. Together, these findings thus demonstrate that biochanin A can alleviate cerebral I/R-induced damage at least in part via suppressing apoptosis, ER stress, and p38 MAPK signaling, thereby serving as a potent neuroprotective agent.

scholarly journals Phosphatidylcholine Synthesis Influences the Diacylglycerol Homeostasis Required for Sec14p-dependent Golgi Function and Cell Growth

2001 ◽  
Vol 12 (3) ◽  
pp. 511-520 ◽  
Author(s):  
Annette L. Henneberry ◽  
Thomas A. Lagace ◽  
Neale D. Ridgway ◽  
Christopher R. McMaster
Keyword(s):  
Cell Death ◽  
Cell Growth ◽  
Phosphatidic Acid ◽  
Metabolic Pathways ◽  
Eukaryotic Cells ◽  
Kennedy Pathway ◽  
Phosphatidylcholine Synthesis ◽  
Long Chain

Phosphatidylcholine and phosphatidylethanolamine are the most abundant phospholipids in eukaryotic cells and thus have major roles in the formation and maintenance of vesicular membranes. In yeast, diacylglycerol accepts a phosphocholine moiety through aCPT1-derived cholinephosphotransferase activity to directly synthesize phosphatidylcholine. EPT1-derived activity can transfer either phosphocholine or phosphoethanolamine to diacylglcyerol in vitro, but is currently believed to primarily synthesize phosphatidylethanolamine in vivo. In this study we report that CPT1- and EPT1-derived cholinephosphotransferase activities can significantly overlap in vivo such that EPT1 can contribute to 60% of net phosphatidylcholine synthesis via the Kennedy pathway. Alterations in the level of diacylglycerol consumption through alterations in phosphatidylcholine synthesis directly correlated with the level of SEC14-dependent invertase secretion and affected cell viability. Administration of synthetic di8:0 diacylglycerol resulted in a partial rescue of cells fromSEC14-mediated cell death. The addition of di8:0 diacylglycerol increased di8:0 diacylglycerol levels 20–40-fold over endogenous long-chain diacylglycerol levels. Di8:0 diacylglcyerol did not alter endogenous phospholipid metabolic pathways, nor was it converted to di8:0 phosphatidic acid.

Sign in / Sign up

Export Citation Format

Share Document