Involvement of TR3/Nur77 translocation to the endoplasmic reticulum in ER stress-induced apoptosis

Human pluripotent stem cells (hPSCs), such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have a well-orchestrated program for differentiation and self-renewal. However, the structural features of unique proteostatic-maintaining mechanisms in hPSCs and their features, distinct from those of differentiated cells, in response to cellular stress remain unclear. We evaluated and compared the morphological features and stress response of hPSCs and fibroblasts. Compared to fibroblasts, electron microscopy showed simpler/fewer structures with fewer networks in the endoplasmic reticulum (ER) of hPSCs, as well as lower expression of ER-related genes according to meta-analysis. As hPSCs contain low levels of binding immunoglobulin protein (BiP), an ER chaperone, thapsigargin treatment sharply increased the gene expression of the unfolded protein response. Thus, hPSCs with decreased chaperone function reacted sensitively to ER stress and entered apoptosis faster than fibroblasts. Such ER stress-induced apoptotic processes were abolished by tauroursodeoxycholic acid, an ER-stress reliever. Hence, our results revealed that as PSCs have an underdeveloped structure and express fewer BiP chaperone proteins than somatic cells, they are more susceptible to ER stress-induced apoptosis in response to stress.

Download Full-text

Selective Activation of Endoplasmic Reticulum Stress by Reactive-Oxygen-Species-Mediated Ochratoxin A-Induced Apoptosis in Tubular Epithelial Cells

International Journal of Molecular Sciences ◽

10.3390/ijms222010951 ◽

2021 ◽

Vol 22 (20) ◽

pp. 10951

Author(s):

Chong-Sun Khoi ◽

Yu-Wen Lin ◽

Jia-Huang Chen ◽

Biing-Hui Liu ◽

Tzu-Yu Lin ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Endoplasmic Reticulum ◽

Er Stress ◽

Ochratoxin A ◽

Reactive Oxygen ◽

Underlying Mechanism ◽

Oxygen Species ◽

Food And Feed ◽

Renal Proximal Tubular Cells ◽

Induced Apoptosis

Ochratoxin A (OTA), one of the major food-borne mycotoxins, impacts the health of humans and livestock by contaminating food and feed. However, the underlying mechanism of OTA nephrotoxicity remains unknown. This study demonstrated that OTA induced apoptosis through selective endoplasmic reticulum (ER) stress activation in human renal proximal tubular cells (HK-2). OTA increased ER-stress-related JNK and precursor caspase-4 cleavage apoptotic pathways. Further study revealed that OTA increased reactive oxygen species (ROS) levels, and N-acetyl cysteine (NAC) could reduce OTA-induced JNK-related apoptosis and ROS levels in HK-2 cells. Our results demonstrate that OTA induced ER stress-related apoptosis through an ROS-mediated pathway. This study provides new evidence to clarify the mechanism of OTA-induced nephrotoxicity.

Download Full-text

Abstract 590: Increased Endoplasmic Reticulum Stress in Atherosclerotic Plaques Associated With Acute Coronary Syndrome

Circulation ◽

10.1161/circ.116.suppl_16.ii_107-a ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Masafumi Myoishi ◽

Testuo Minamino ◽

Masafumi Kitakaze

Keyword(s):

Endoplasmic Reticulum ◽

Coronary Artery ◽

Er Stress ◽

Atherosclerotic Plaques ◽

Coronary Syndrome ◽

Er Chaperone ◽

Unstable Plaques ◽

Induced Apoptosis ◽

Stress Dependent ◽

Dependent Pathway

Background Endoplasmic reticulum (ER) responds to various stresses by up-regulation of ER chaperones, and prolonged ER stress eventually causes apoptosis. Although apoptosis is considered to be essential for the progression and rupture of atherosclerotic plaques, the influence of ER stress and apoptosis on rupture of unstable coronary plaques remains unclear. Methods and Results We obtained 152 coronary artery segments at autopsy and 40 atherectomy specimens from 71 and 40 patients, respectively . Smooth muscle cells (SMCs) and macrophages in the fibrous caps of thin cap atheroma and ruptured plaques, but not in the fibrous caps of thick cap atheroma and fibrous plaques, showed a marked increase in the expression of ER chaperone and numbers of apoptotic cells. ER chaperones also expressed higher in atherectomy specimens from patients with unstable angina pectoris than with stable angina. To explore the plausible molecular mechanism of activation of ER stress and the mechanistic link to apoptosis, we investigated plaque lipids such as oxysterols. Among oxysterols, expression of 7-ketocholesterol was increased in the fibrous caps of thin cap atheroma compared with thick cap atheroma. Treatment of either cultured coronary artery SMCs or THP-1 cells with 7-ketocholesterol induced upregulation of ER chaperones and apoptosis, while these changes were prevented by antioxidants. We also investigated possible signaling pathways for ER-initiated apoptosis and found that the CHOP (a transcription factor induced by ER stress)-dependent pathway was activated in unstable plaques. In addition, knockdown of CHOP expression by siRNA decreased ER stress-dependent death of cultured coronary artery SMCs and THP-1 cells. Conclusions Increased ER stress occurs in unstable plaques. Our findings suggest that ER stress-induced apoptosis of SMCs and macrophages may contribute to plaque vulnerability.

Download Full-text

Japanese Encephalitis Virus Induces Apoptosis and Encephalitis by Activating the PERK Pathway

Journal of Virology ◽

10.1128/jvi.00887-19 ◽

2019 ◽

Vol 93 (17) ◽

Cited By ~ 6

Author(s):

Qianruo Wang ◽

Xiu Xin ◽

Ting Wang ◽

Jiawu Wan ◽

Yangtao Ou ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Japanese Encephalitis Virus ◽

Japanese Encephalitis ◽

Encephalitis Virus ◽

Protein Kinase R ◽

Apoptosis Pathway ◽

Stress Sensor ◽

Sensor Protein ◽

Induced Apoptosis

ABSTRACTAccumulated evidence demonstrates that Japanese encephalitis virus (JEV) infection triggers endoplasmic reticulum (ER) stress and neuron apoptosis. ER stress sensor protein kinase R-like endoplasmic reticulum kinase (PERK) has been reported to induce apoptosis under acute or prolonged ER stress. However, the precise role of PERK in JEV-induced apoptosis and encephalitis remains unknown. Here, we report that JEV infection activates the PERK-ATF4-CHOP apoptosis pathway bothin vitroandin vivo. PERK activation also promotes the formation of stress granule, which in turn represses JEV-induced apoptosis. However, PERK inhibitor reduces apoptosis, indicating that JEV-activated PERK predominantly induces apoptosis via the PERK-ATF4-CHOP apoptosis pathway. Among JEV proteins that have been reported to induce ER stress, only JEV NS4B can induce PERK activation. PERK has been reported to form an active molecule by dimerization. The coimmunoprecipitation assay shows that NS4B interacts with PERK. Moreover, glycerol gradient centrifugation shows that NS4B induces PERK dimerization. Both the LIG-FHA and the LIG-WD40 domains within NS4B are required to induce PERK dimerization, suggesting that JEV NS4B pulls two PERK molecules together by simultaneously interacting with them via different motifs. PERK deactivation reduces brain cell damage and encephalitis during JEV infection. Furthermore, expression of JEV NS4B is sufficient to induce encephalitis via PERK in mice, indicating that JEV activates PERK primarily via its NS4B to cause encephalitis. Taken together, our findings provide a novel insight into JEV-caused encephalitis.IMPORTANCEJapanese encephalitis virus (JEV) infection triggers endoplasmic reticulum (ER) stress and neuron apoptosis. ER stress sensor protein kinase R-like endoplasmic reticulum kinase (PERK) has been reported to induce apoptosis under acute or prolonged ER stress. However, whether the PERK pathway of ER stress response plays important roles in JEV-induced apoptosis and encephalitis remains unknown. Here, we found that JEV infection activates ER stress sensor PERK in neuronal cells and mouse brains. PERK activation induces apoptosis via the PERK-ATF4-CHOP apoptosis pathway upon JEV infection. Among the JEV proteins prM, E, NS1, NS2A, NS2B, and NS4B, only NS4B activates PERK. Moreover, activated PERK participates in apoptosis and encephalitis induced by JEV and NS4B. These findings provide a novel therapeutic approach for JEV-caused encephalitis.

Download Full-text

Sirtuin-3 (SIRT3) protects pancreatic β-cells from endoplasmic reticulum (ER) stress-induced apoptosis and dysfunction

Molecular and Cellular Biochemistry ◽

10.1007/s11010-016-2771-5 ◽

2016 ◽

Vol 420 (1-2) ◽

pp. 95-106 ◽

Cited By ~ 15

Author(s):

Hao-Hao Zhang ◽

Xiao-Jun Ma ◽

Li-Na Wu ◽

Yan-Yan Zhao ◽

Peng-Yu Zhang ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Sirtuin 3 ◽

Β Cells ◽

Pancreatic Β Cells ◽

Induced Apoptosis

Download Full-text

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

MHR Basic science of reproductive medicine ◽

10.1093/molehr/gaz066 ◽

2019 ◽

Vol 26 (1) ◽

pp. 40-52 ◽

Cited By ~ 2

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.

Download Full-text

Novel targets for endoplasmic reticulum stress-induced apoptosis in B-CLL

Blood ◽

10.1182/blood-2010-03-275628 ◽

2010 ◽

Vol 116 (15) ◽

pp. 2713-2723 ◽

Cited By ~ 53

Author(s):

Emanuela Rosati ◽

Rita Sabatini ◽

Giuliana Rampino ◽

Filomena De Falco ◽

Mauro Di Ianni ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Cell Apoptosis ◽

Ex Vivo ◽

Lymphocytic Leukemia ◽

Minor Role ◽

Caspase 8 ◽

Caspase 9 ◽

Cytochrome C Release ◽

Induced Apoptosis

Abstract A better understanding of apoptotic signaling in B-chronic lymphocytic leukemia (B-CLL) cells may help to define new therapeutic strategies. This study investigated endoplasmic reticulum (ER) stress signaling in spontaneous apoptosis of B-CLL cells and whether manipulating ER stress increases their apoptosis. Results show that a novel ER stress-triggered caspase cascade, initiated by caspase-4 and involving caspase-8 and -3, plays an important role in spontaneous B-CLL cell apoptosis. ER stress-induced apoptosis in B-CLL cells also involves CHOP/GADD153 up-regulation, increased JNK1/2 phosphorylation, and caspase-8–mediated cleavage of Bap31 to Bap20, known to propagate apoptotic signals from ER to mitochondria. In ex vivo B-CLL cells, some apoptotic events associated with mitochondrial pathway also occur, including mitochondrial cytochrome c release and caspase-9 processing. However, pharmacologic inhibition studies show that caspase-9 plays a minor role in B-CLL cell apoptosis. ER stress also triggers survival signals in B-CLL cells by increasing BiP/GRP78 expression. Manipulating ER signaling by siRNA down-regulation of BiP/GRP78 or treating B-CLL cells with 2 well-known ER stress-inducers, tunicamycin and thapsigargin, increases their apoptosis. Overall, our findings show that ER triggers an essential pathway for B-CLL cell apoptosis and suggest that genetic and pharmacologic manipulation of ER signaling could represent an important therapeutic strategy.

Download Full-text

The Molecular Mechanism of Endoplasmic Reticulum Stress-Induced Apoptosis in PC-12 Neuronal Cells: The Protective Effect of Insulin-Like Growth Factor I

Endocrinology ◽

10.1210/en.2008-0794 ◽

2008 ◽

Vol 150 (1) ◽

pp. 277-285 ◽

Cited By ~ 55

Author(s):

Cheng-Gang Zou ◽

Xiu-Zhen Cao ◽

Yue-Shui Zhao ◽

Shun-Yu Gao ◽

Shu-De Li ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Protective Effect ◽

Er Stress ◽

P38 Mapk ◽

Neuronal Apoptosis ◽

Neuronal Cells ◽

Dependent Manner ◽

Related Protein ◽

Igf I ◽

Induced Apoptosis

Endoplasmic reticulum (ER) stress has been implicated in several neurodegenerative diseases. Although CCAAT/enhancer-binding protein homologous protein (CHOP) has been shown to play a critical role in ER stress, the precise apoptosis cascade downstream of CHOP is unknown. In this report, we investigated the mechanism of ER stress-mediated apoptosis as well as the action of IGF-I in PC-12 neuronal cells. Our results demonstrated that tribbles-related protein 3 (TRB3), which is a target gene of CHOP, was responsible for tunicamycin (an ER stress inducer)-induced apoptosis. TRB3 could promote dephosphorylation of Akt in PC-12 cells. IGF-I inhibited ER stress-induced apoptosis by restoring the phosphorylation level of Akt. Both wortmannin (a phosphatidylinositide 3-kinase inhibitor) and SB 212090 (a p38 MAPK inhibitor) suppressed the protective effect of IGF-I on ER stress-induced apoptosis. Interestingly, IGF-I attenuated ER stress-mediated expression of TRB3 but not CHOP. This action of IGF-I was abolished by SB 212090 but not by wortmannin. Immunoprecipitation analysis revealed that IGF-I promoted the phosphorylation of CHOP by activating p38 MAPK, probably leading to a decrease in the transcriptional activity of CHOP. The dephosphorylation of Akt resulted in increased expression of a proapoptotic protein, p53 up-regulated modulator of apoptosis (PUMA), in a forkhead box O3a-dependent manner. Knockdown of PUMA by short hairpin RNA attenuated ER stress-mediated apoptosis. Thus, our current study indicates that both TRB3 and PUMA are critical molecules in ER stress-induced apoptosis. IGF-I effectively protects PC-12 neuronal cells against ER stress-induced apoptosis through the phosphatidylinositide 3-kinase/Akt and p38 MAPK pathways. Endoplasmic reticulum (ER) stress causes neuronal apoptosis by inducing the expression of tribbles-related protein 3 and PUMA. IGF-1 prevents neuronal apoptosis against ER stress through phosphatidylinositide 3-kinase/Akt and p38 mitogen-activated protein kinase pathways.

Download Full-text

A novel endoplasmic stress mediator, Kelch domain containing 7B (KLHDC7B), increased Harakiri (HRK) in the SubAB-induced apoptosis signaling pathway

Cell Death Discovery ◽

10.1038/s41420-021-00753-0 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Kinnosuke Yahiro ◽

Kohei Ogura ◽

Hiroyasu Tsutsuki ◽

Sunao Iyoda ◽

Makoto Ohnishi ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Er Stress ◽

Signaling Pathway ◽

Gastrointestinal Symptoms ◽

Parp Cleavage ◽

Rna Seq ◽

Gene Encoding ◽

Apoptotic Pathway ◽

Kelch Domain ◽

Induced Apoptosis

AbstractLocus for Enterocyte Effacement (LEE)-positive Shiga-toxigenic Escherichia coli (STEC) contributes to many global foodborne diseases, with infection characterized by severe gastrointestinal symptoms, including bloody diarrhea. The incidence of LEE-negative STEC-mediated disease is also increasing globally. Subtilase cytotoxin (SubAB) is released by some LEE-negative STEC strains. It cleaves BiP, which is a chaperone protein located in the endoplasmic reticulum (ER), thereby causing apoptosis induced by ER stress. To date, the apoptotic signaling pathway mediated by SubAB has not been identified. In the current study, RNA-seq analysis showed that SubAB significantly induced the expression of Kelch domain containing 7B (KLHDC7B). We explored the role of KLHDC7B in the SubAB-induced apoptotic pathway. SubAB-induced KLHDC7B mRNA expression was increased after 12 h of incubation of toxin with HeLa cells. KLHDC7B expression was downregulated by knockdown of PKR-like endoplasmic reticulum kinase (PERK), CEBP homologous protein (CHOP), activating transcription factor 4 (ATF4), and CEBP β (CEBPB). KLHDC7B knockdown suppressed SubAB-stimulated CHOP expression, poly(ADP-ribose) polymerase (PARP) cleavage, and cytotoxicity. The over-expressed KLHDC7B was localized to the nucleus and cytosolic fractions. Next, we used RNA-seq to analyze the effect of KLHDC7B knockdown on apoptosis induced by SubAB, and found that the gene encoding for the pro-apoptotic Bcl-2 family protein, Harakiri (HRK), was upregulated in SubAB-treated control cells. However, this effect was not observed in SubAB-treated KLHDC7B-knockdown cells. Therefore, we identified the pathway through which SubAB-induced KLHDC7B regulates HRK expression, which is essential for apoptosis in toxin-mediated ER stress.

Download Full-text

Deltamethrin Induces Apoptosis in Cerebrum Neurons of Quail via Promoting Endoplasmic Reticulum Stress and Mitochondrial Dysfunction

10.21203/rs.3.rs-808891/v1 ◽

2021 ◽

Author(s):

Pengfei Wu ◽

Bing Han ◽

Qingyue Yang ◽

Siyu Li ◽

Xiaoqiao Wang ◽

...

Keyword(s):

Oxidative Stress ◽

Endoplasmic Reticulum ◽

Er Stress ◽

Mitochondrial Dysfunction ◽

Chronic Exposure ◽

Molecular Mechanisms ◽

Atp Content ◽

Histological Changes ◽

Real Time Quantitative Pcr ◽

Induced Apoptosis

Abstract Deltamethrin (DLM) is a widely used and highly effective insecticide. DLM exposure is harmful to animal and human. Quail, as a bird model, has been widely used in the toxicology field. However, there is little information available in the literature about quail cerebrum damage caused by DLM. Here, we investigated the effect of DLM on quail cerebrum neurons. Four groups of healthy quails were assigned (10 quails in each group), respectively given 0, 15, 30, and 45 mg/kg DLM by gavage for 12 weeks. Through the measurements of quail cerebrum, it was found that DLM exposure induced obvious histological changes, oxidative stress, and neurons apoptosis. To further explore the possible molecular mechanisms, we performed real-time quantitative PCR to detect the expression of endoplasmic reticulum (ER) stress-related mRNA. In addition, we detected ATP content in quail cerebrum to evaluate the functional status of mitochondria. The study showed that DLM exposure significantly increased the expression of ER stress-related mRNA and decreased ATP content in quail cerebrum. These results suggest that chronic exposure to DLM induces apoptosis of quail cerebrum neurons via promoting ER stress and mitochondrial dysfunction. Furthermore, our results provide a novel explanation for DLM-induced apoptosis of avian cerebrum neurons.

Download Full-text