Endoplasmic Reticulum Stress-induced Death of Mouse Embryonic Fibroblasts Requires the Intrinsic Pathway of Apoptosis

ABSTRACT Ubiquitin conjugation typically requires three classes of enzyme: E1, E2, and E3. A fourth type of enzyme (E4), however, was recently shown to be required for the degradation of certain types of substrate in yeast. We previously identified UFD2a (also known as E4B) as an E4 in mammals. UFD2a is exclusively expressed in cardiac muscle during mouse embryonic development, but it is abundant in neurons of adult mice and is implicated in the pathogenesis of neurodegenerative disease. The precise physiological function of this enzyme has remained largely unknown, however. Here, we show that mice lacking UFD2a die in utero, manifesting marked apoptosis in the developing heart. Polyubiquitylation activity for an E4 substrate was greatly reduced in Ufd2a −/− mouse embryonic fibroblasts. Furthermore, Ufd2a +/− mice displayed axonal dystrophy in the nucleus gracilis, as well as degeneration of Purkinje cells accompanied by endoplasmic reticulum stress. These animals also developed a neurological disorder. UFD2a thus appears to be essential for the development of cardiac muscle, as well as for the protection of spinocerebellar neurons from degeneration induced by endoplasmic reticulum stress.

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The pterocarpanquinone LQB 118 induces apoptosis in tumor cells through the intrinsic pathway and the endoplasmic reticulum stress pathway

Anti-Cancer Drugs ◽

10.1097/cad.0b013e3283592da8 ◽

2013 ◽

Vol 24 (1) ◽

pp. 73-83 ◽

Cited By ~ 11

Author(s):

Thiago de Sá Bacelar ◽

Alcides J. da Silva ◽

Paulo R.R. Costa ◽

Vivian M. Rumjanek

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Tumor Cells ◽

Intrinsic Pathway ◽

Endoplasmic Reticulum Stress Pathway ◽

Stress Pathway

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Faculty Opinions recommendation of Coupling endoplasmic reticulum stress to the cell death program. An Apaf-1-independent intrinsic pathway.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1007724.97655 ◽

2002 ◽

Author(s):

Yigong Shi

Keyword(s):

Endoplasmic Reticulum ◽

Cell Death ◽

Endoplasmic Reticulum Stress ◽

Intrinsic Pathway ◽

Cell Death Program

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Bcl-XL specifically activates Bak to induce swelling and restructuring of the endoplasmic reticulum

The Journal of Cell Biology ◽

10.1083/jcb.200408169 ◽

2005 ◽

Vol 168 (5) ◽

pp. 723-734 ◽

Cited By ~ 51

Author(s):

Martina Klee ◽

Felipe X. Pimentel-Muiños

Keyword(s):

Endoplasmic Reticulum ◽

Ryanodine Receptor ◽

Functional Divergence ◽

Deficient Mouse ◽

Channel Activity ◽

Mouse Embryonic Fibroblasts ◽

Embryonic Fibroblasts ◽

Bh3 Domain ◽

Additional Capacity

Bcl-2 family members Bak and Bax constitute a mitochondrial gateway for multiple death pathways. Both proteins are also present in the endoplasmic reticulum where they control apoptosis through the regulation of calcium levels. We show here that reticular Bak has the additional capacity of modulating the structure of this organelle. Coexpression of Bak and Bcl-XL provokes extensive swelling and vacuolization of reticular cisternae. A Bak version lacking the BH3 domain suffices to induce this phenotype, and reticular targeting of this mutant retains the activity. Expression of upstream BH3-only activators in similar conditions recapitulates ER swelling and vacuolization if ryanodine receptor calcium channel activity is inhibited. Experiments with Bak and Bax-deficient mouse embryonic fibroblasts show that endogenous Bak mediates the effect, whereas Bax is mainly irrelevant. These results reveal a previously unidentified role of Bak in regulating reticular conformation. Because this activity is absent in Bax, it constitutes one of the first examples of functional divergence between the two multidomain homologues.

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

Endocrinology ◽

10.1210/en.2008-0024 ◽

2008 ◽

Vol 149 (7) ◽

pp. 3267-3273 ◽

Cited By ~ 72

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.

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Equol induces apoptosis in human hepatocellular carcinoma SMMC-7721 cells through the intrinsic pathway and the endoplasmic reticulum stress pathway

Anti-Cancer Drugs ◽

10.1097/cad.0000000000000085 ◽

2014 ◽

pp. 1 ◽

Cited By ~ 5

Author(s):

Xiao-Lin Liang ◽

Meng Li ◽

Jing Li ◽

Xiu-Ling Wang

Keyword(s):

Hepatocellular Carcinoma ◽

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Stress ◽

Human Hepatocellular Carcinoma ◽

Intrinsic Pathway ◽

Endoplasmic Reticulum Stress Pathway ◽

Stress Pathway

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UDP-glucose:glycoprotein glucosyltransferase (UGGT1) promotes substrate solubility in the endoplasmic reticulum

Molecular Biology of the Cell ◽

10.1091/mbc.e13-02-0101 ◽

2013 ◽

Vol 24 (17) ◽

pp. 2597-2608 ◽

Cited By ~ 25

Author(s):

Sean P. Ferris ◽

Nikita S. Jaber ◽

Maurizio Molinari ◽

Peter Arvan ◽

Randal J. Kaufman

Keyword(s):

Endoplasmic Reticulum ◽

Central Component ◽

Deficiency Disease ◽

Mouse Embryonic Fibroblasts ◽

Embryonic Fibroblasts ◽

Er Quality Control ◽

Unfolded Protein ◽

Glycosylation Sites ◽

Folded Proteins ◽

Protein Response

Protein folding in the endoplasmic reticulum (ER) is error prone, and ER quality control (ERQC) processes ensure that only correctly folded proteins are exported from the ER. Glycoproteins can be retained in the ER by ERQC, and this retention contributes to multiple human diseases, termed ER storage diseases. UDP-glucose:glycoprotein glucosyltransferase (UGGT1) acts as a central component of glycoprotein ERQC, monoglucosylating deglucosylated N-glycans of incompletely folded glycoproteins and promoting subsequent reassociation with the lectin-like chaperones calreticulin and calnexin. The extent to which UGGT1 influences glycoprotein folding, however, has only been investigated for a few selected substrates. Using mouse embryonic fibroblasts lacking UGGT1 or those with UGGT1 complementation, we investigated the effect of monoglucosylation on the soluble/insoluble distribution of two misfolded α1-antitrypsin (AAT) variants responsible for AAT deficiency disease: null Hong Kong (NHK) and Z allele. Whereas substrate solubility increases directly with the number of N-linked glycosylation sites, our results indicate that additional solubility is conferred by UGGT1 enzymatic activity. Monoglucosylation-dependent solubility decreases both BiP association with NHK and unfolded protein response activation, and the solubility increase is blocked in cells deficient for calreticulin. These results suggest that UGGT1-dependent monoglucosylation of N-linked glycoproteins promotes substrate solubility in the ER.

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