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Chou CK, Liu W, Hong YJ, Dahms HU, Chiu CH, Chang WT, Chien CM, Yen CH, Cheng YB, Chiu CC. Ethyl Acetate Extract of Scindapsus cf. hederaceus Exerts the Inhibitory Bioactivity on Human Non-Small Cell Lung Cancer Cells through Modulating ER Stress. Int J Mol Sci 2018; 19:ijms19071832. [PMID: 29933620 PMCID: PMC6073426 DOI: 10.3390/ijms19071832] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 06/13/2018] [Indexed: 01/09/2023] Open
Abstract
Unfolded protein response (UPR) is a cytoprotective mechanism that alleviates the protein-folding burden in eukaryotic organisms. Moderate activation of UPR is required for maintaining endoplasmic reticulum (ER) homeostasis and profoundly contributes to tumorigenesis. Defects in UPR signaling are implicated in the attenuation of various malignant phenotypes including cell proliferation, migration, and invasion, as well as angiogenesis. This suggests UPR as a promising target in cancer therapy. The pharmacological effects of the plant Scindapsus cf. hederaceus on human cancer cell lines is not understood. In this study, we identified an ethyl acetate extract from Scindapsus cf. hederaceus (SH-EAE), which markedly altered the protein expression of UPR-related genes in human non-small cell lung cancer (NSCLC) cells. Treatment with the SH-EAE led to the dose-dependent suppression of colony forming ability of both H1299 and H460 cells, but not markedly in normal bronchial epithelial BEAS-2B cells. SH-EAE treatment also attenuated the migration and invasion ability of H1299 and H460 cells. Moreover, SH-EAE strikingly suppressed the protein expression of two ER stress sensors, including inositol requiring enzyme-1α (IRE-1α) and protein kinase R-like ER kinase (PERK), and antagonized the induction of C/EBP homologous protein (CHOP) expression by thapsigargin, an ER stress inducer. SH-EAE induced the formation of massive vacuoles which are probably derived from ER. Importantly, SH-EAE impaired the formation of intersegmental vessels (ISV) in zebrafish larvae, an index of angiogenesis, but had no apparent effect on the rate of larval development. Together, our findings demonstrate, for the first time, that the ability of SH-EAE specifically targets the two sensors of UPR, with significant anti-proliferation and anti-migration activities as a crude extract in human NSCLC cells. Our finding also indicates potential applications of SH-EAE in preventing UPR activation in response to Tg-induced ER stress. We suggest that SH-EAE attenuates UPR adaptive pathways for rendering the NSCLC cells intolerant to ER stress.
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Affiliation(s)
- Chon-Kit Chou
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Wangta Liu
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Yu-Jie Hong
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Hans-Uwe Dahms
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Chen-Hao Chiu
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Wen-Tsan Chang
- Division of General and Digestive Surgery, Department of Surgery, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- Department of Surgery, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Ching-Ming Chien
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Chia-Hung Yen
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Yuan-Bin Cheng
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Center for Infectious Disease and Cancer Research, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
| | - Chien-Chih Chiu
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Research Center for Environment Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
- Center for Stem Cell Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan.
- Translational Research Center, Cancer Center and Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.
- The Graduate Institute of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
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Abstract
CONTEXT Molecular pathogenesis of chronic alcoholism is linked to increased endoplasmic reticulum stress. Ethanol is a competitive inhibitor of vitamin A metabolism and vitamin A supplementation aggravates existing liver problems. Hence, we probed into the impact of supplementation of all trans retinoic acid (ATRA), the active metabolite of vitamin A on ethanol-induced endoplasmic reticulcum stress. METHODS Male Sprague-Dawley rats were divided into four groups - I: Control; II: Ethanol; III: ATRA; IV: ATRA + Ethanol. After 90 days the animals were sacrificed to study markers of lipid peroxidation in hepatic microsomal fraction and expression of ER stress proteins and apoptosis in liver. RESULTS AND CONCLUSION Ethanol caused hepatic hyperlipidemia, enhanced microsomal lipid peroxidation, upregulated expression of unfolded protein response associated proteins and that of apoptosis. Ethanol also led to downregulation of retinoid receptors. ATRA supplementation reversed all these alterations indicating the decrease in ethanol-induced endoplasmic reticulum stress.
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Affiliation(s)
- Saritha S Nair
- a Department of Biochemistry , University of Kerala , Thiruvananthapuram , Kerala , India
| | - Syam Das S
- a Department of Biochemistry , University of Kerala , Thiruvananthapuram , Kerala , India
| | - Reshma P Nair
- b Agroprocessing and Technology Division , CSIR-NIIST , Thiruvananthapuram , Kerala , India
| | - M Indira
- a Department of Biochemistry , University of Kerala , Thiruvananthapuram , Kerala , India
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Huang H, Xie H, Pan Y, Zheng K, Xia Y, Chen W. Plumbagin Triggers ER Stress-Mediated Apoptosis in Prostate Cancer Cells via Induction of ROS. Cell Physiol Biochem 2018; 45:267-280. [PMID: 29357323 DOI: 10.1159/000486773] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 12/09/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Prostate cancer (PCa) is the second most frequently diagnosed cancer in men worldwide. Currently available therapies for hormone-refractory PCa are only marginally effective. Plumbagin (PLB), a natural naphthoquinone isolated from the traditional folk medicine Plumbago zeylanica, is known to selectively kill tumor cells. Nevertheless, antitumor mechanisms initiated by PLB in cancer cells have not been fully defined. METHODS MTT assay was used to evaluate the effect of PLB on the viability of cancer cells. Cell apoptosis and reactive oxygen species (ROS) production were determined by flow cytometry. Protein expression was detected by western blotting. In vivo anti-tumor effect was measured by using tumor xenoqraft model in nude mice. RESULTS In the present study, we found that PLB decreases cancer cell growth and induces apoptosis in DU145 and PC-3 cells. In addition, by increasing intracellular ROS levels, PLB induced a lethal endoplasmic reticulum stress response in PCa cells. Importantly, blockage of ROS production significantly reversed PLB-induced ER stress activation and cell apoptosis. In vivo, we found that PLB inhibits the growth of PCa xenografts without exhibiting toxicity Treatment of mice bearing human PCa xenografts with PLB was also associated with induction of ER stress activation. CONCLUSION Inducing ER stress by PLB thus discloses a previously unrecognized mechanism underlying the biological activity of PLB and provides an in-depth insight into the action of PLB in the treatment of hormone-refractory PCa.
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Ladin DA, Soliman E, Escobedo R, Fitzgerald TL, Yang LV, Burns C, Van Dross R. Synthesis and Evaluation of the Novel Prostamide, 15-Deoxy, Δ 12,14-Prostamide J 2, as a Selective Antitumor Therapeutic. Mol Cancer Ther 2017; 16:838-849. [PMID: 28292936 DOI: 10.1158/1535-7163.mct-16-0484] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 08/18/2016] [Accepted: 02/17/2017] [Indexed: 11/16/2022]
Abstract
15-deoxy, Δ12,14-prostaglandin J2-ethanolamide, also known as 15-deoxy, Δ12,14-prostamide J2 (15d-PMJ2) is a novel product of the metabolism of arachidonoyl ethanolamide (AEA) by COX-2. 15d-PMJ2 preferentially induced cell death and apoptosis in tumorigenic A431 keratinocytes and B16F10 melanoma cells compared with nontumorigenic HaCaT keratinocytes and Melan-A melanocytes. Activation of the ER stress execution proteins, PERK and CHOP10, was evaluated to determine whether this process was involved in 15d-PMJ2 cell death. 15d-PMJ2 increased the phosphorylation of PERK and expression of CHOP10 in tumorigenic but not nontumorigenic cells. The known ER stress inhibitors, salubrinal and 4-phenylbutaric acid, significantly inhibited 15d-PMJ2-mediated apoptosis, suggesting ER stress as a primary apoptotic mediator. Furthermore, the reactive double bond present within the cyclopentenone structure of 15d-PMJ2 was identified as a required moiety for the induction of ER stress apoptosis. The effect of 15d-PMJ2 on B16F10 melanoma growth was also evaluated by dosing C57BL/6 mice with 0.5 mg/kg 15d-PMJ2 Tumors of animals treated with 15d-PMJ2 exhibited significantly reduced growth and mean weights compared with vehicle and untreated animals. TUNEL and IHC analysis of tumor tissues showed significant cell death and ER stress in tumors of 15d-PMJ2-treated compared with control group animals. Taken together, these findings suggest that the novel prostamide, 15d-PMJ2, possesses potent antitumor activity in vitro and in vivoMol Cancer Ther; 16(5); 838-49. ©2017 AACR.
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Affiliation(s)
- Daniel A Ladin
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, North Carolina
| | - Eman Soliman
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Zagazig University, Egypt
| | - Rene Escobedo
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, North Carolina
| | | | - Li V Yang
- Department of Internal Medicine, Brody School of Medicine, East Carolina University, Greenville, North Carolina
| | - Colin Burns
- Department of Chemistry, East Carolina University, Greenville, North Carolina
| | - Rukiyah Van Dross
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, North Carolina.
- Center for Health Disparities, East Carolina University, Greenville, North Carolina
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Ma Z, Fan C, Yang Y, Di S, Hu W, Li T, Zhu Y, Han J, Xin Z, Wu G, Zhao J, Li X, Yan X. Thapsigargin sensitizes human esophageal cancer to TRAIL-induced apoptosis via AMPK activation. Sci Rep 2016; 6:35196. [PMID: 27731378 PMCID: PMC5059685 DOI: 10.1038/srep35196] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/26/2016] [Indexed: 12/22/2022] Open
Abstract
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent for esophageal squamous cell carcinoma (ESCC). Forced expression of CHOP, one of the key downstream transcription factors during endoplasmic reticulum (ER) stress, upregulates the death receptor 5 (DR5) levels and promotes oxidative stress and cell death. In this study, we show that ER stress mediated by thapsigargin promoted CHOP and DR5 synthesis thus sensitizing TRAIL treatment, which induced ESCC cells apoptosis. These effects were reversed by DR5 siRNA in vitro and CHOP siRNA both in vitro and in vivo. Besides, chemically inhibition of AMPK by Compound C and AMPK siRNA weakened the anti-cancer effect of thapsigargin and TRAIL co-treatment. Therefore, our findings suggest ER stress effectively sensitizes human ESCC to TRAIL-mediated apoptosis via the TRAIL-DR5-AMPK signaling pathway, and that activation of ER stress may be beneficial for improving the efficacy of TRAIL-based anti-cancer therapy.
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Affiliation(s)
- Zhiqiang Ma
- Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, 1 Xinsi Road, Xi'an 710038, China
| | - Chongxi Fan
- Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, 1 Xinsi Road, Xi'an 710038, China
| | - Yang Yang
- Department of Thoracic and Cardiovascular Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing 210008, Jiangsu, China
- Department of Biomedical Engineering, The Fourth Military Medical University, 169 Changle West Road, Xi'an 710032, China
| | - Shouyin Di
- Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, 1 Xinsi Road, Xi'an 710038, China
| | - Wei Hu
- Department of Biomedical Engineering, The Fourth Military Medical University, 169 Changle West Road, Xi'an 710032, China
| | - Tian Li
- Department of Biomedical Engineering, The Fourth Military Medical University, 169 Changle West Road, Xi'an 710032, China
| | - Yifang Zhu
- Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, 1 Xinsi Road, Xi'an 710038, China
| | - Jing Han
- Department of Ophthalmology, Tangdu Hospital, The Fourth Military Medical University, 1 Xinsi Road, Xi'an 710038, China
| | - Zhenlong Xin
- Department of Biomedical Engineering, The Fourth Military Medical University, 169 Changle West Road, Xi'an 710032, China
| | - Guiling Wu
- Department of Biomedical Engineering, The Fourth Military Medical University, 169 Changle West Road, Xi'an 710032, China
| | - Jing Zhao
- Department of Thoracic Surgery, Beijing Military General Hospital, 5 DongSi ShiTiao Road 100070, Beijing 100700, China
| | - Xiaofei Li
- Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, 1 Xinsi Road, Xi'an 710038, China
| | - Xiaolong Yan
- Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, 1 Xinsi Road, Xi'an 710038, China
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Kim JK, Kang KA, Ryu YS, Piao MJ, Han X, Oh MC, Boo SJ, Jeong SU, Jeong YJ, Chae S, Na SY, Hyun JW. Induction of Endoplasmic Reticulum Stress via Reactive Oxygen Species Mediated by Luteolin in Melanoma Cells. Anticancer Res 2016; 36:2281-2289. [PMID: 27127134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/08/2016] [Indexed: 06/05/2023]
Abstract
BACKGROUND This study aimed to investigate whether luteolin, a flavonoid, induces apoptosis in human melanoma cells via endoplasmic reticulum (ER) stress. MATERIALS AND METHODS To investigate the effects of luteolin in human melanoma cells, the anti-proliferation, apoptosis, ER stress induction and reactive oxygen species (ROS) generation were evaluated using MTT, Hoechst 33342, ER-tracker Blue White DPX and DCF-DA staining assays, respectively. RESULTS Luteolin inhibited cell proliferation and increased apoptotic body formation. Luteolin induced ER stress, as shown by ER staining and mitochondrial Ca(2+) overloading. Luteolin increased expression of the ER stress-related proteins; protein kinase RNA-like ER kinase, phospho eukaryotic translation initiation factor 2α, activating transcription factor (ATF) 6, CCAAT/enhancer-binding protein-homologous protein (CHOP), and cleaved caspase 12. Furthermore, luteolin increased the level of intracellular ROS, leading to ROS-mediated apoptosis and ER stress. However, N-acetyl cysteine, a ROS scavenger, decreased ROS levels, apoptosis, and ER stress induced by luteolin treatment. In addition, knockdown of CHOP and ATF6 by small-interfering RNA inhibited luteolin-induced cell death. CONCLUSION Luteolin induces apoptosis by ER stress via increasing ROS levels.
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Affiliation(s)
- Joon Ki Kim
- Department of Bio and Nanochemistry, Kookmin University, Seoul, Republic of Korea
| | - Kyoung Ah Kang
- School of Medicine, Jeju National University, Jeju, Republic of Korea
| | - Yea Seong Ryu
- School of Medicine, Jeju National University, Jeju, Republic of Korea
| | - Mei Jing Piao
- School of Medicine, Jeju National University, Jeju, Republic of Korea
| | - Xia Han
- School of Medicine, Jeju National University, Jeju, Republic of Korea
| | - Min Chang Oh
- School of Medicine, Jeju National University, Jeju, Republic of Korea
| | - Sun Jin Boo
- School of Medicine, Jeju National University, Jeju, Republic of Korea
| | - Seung Uk Jeong
- School of Medicine, Jeju National University, Jeju, Republic of Korea
| | - Yong Joo Jeong
- Department of Bio and Nanochemistry, Kookmin University, Seoul, Republic of Korea
| | - Sungwook Chae
- KM Based Herbal Drug Development Group, Korea Institute of Oriental Medicine, Daejeon, Republic of Korea
| | - Soo-Young Na
- School of Medicine, Jeju National University, Jeju, Republic of Korea
| | - Jin Won Hyun
- School of Medicine, Jeju National University, Jeju, Republic of Korea
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Jeon BJ, Yang HM, Lyu YS, Pae HO, Ju SM, Jeon BH. Apigenin inhibits indoxyl sulfate-induced endoplasmic reticulum stress and anti-proliferative pathways, CHOP and IL-6/p21, in human renal proximal tubular cells. Eur Rev Med Pharmacol Sci 2015; 19:2303-2310. [PMID: 26166660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
OBJECTIVE Indoxyl sulfate (IS) has been reported to induce endoplasmic reticulum (ER) stress in tubular cells and to inhibit the cell proliferation via ER stress and ERK/IL-6/p21 pathways. This study has investigated the effect of apigenin on IS-induced ER stress in immortalized human renal proximal tubular HK-2 cells. MATERIALS AND METHODS Human Kidney 2 (HK-2) cells were treated with IS (5 mM) in the absence or presence of apigenin (10 μM) or salubrinal (20 μM) for indicated times under the serum-free condition. Cell viability was evaluated by MTT assay. The levels of protein expression and phosphorylation were evaluated by Western blot analysis. RESULTS In HK-2 cells, apigenin completely inhibited IS-induced ER stress, as indicated by decreased expression of CHOP, ATF4 and GRP78, although the phosphorylated level of eIF2α did not decrease. IS-induced expression levels of IL-6 and p21 proteins were also inhibited by apigenin, with no significant changes in ERK activation. The suppression of cell proliferation by IS was abolished by salubrinal, an ER stress inhibitor, but not by apigenin. Apigenin inhibited the phosphorylation of Akt and GSK-3β in IS-treated HK-2 cells. The phosphorylation of GSK-3β, which was inhibited by apigenin, resulted in hypo-phosphorylation of retinoblastoma (Rb) protein, which was associated with the decrease in cyclin D1 expression. CONCLUSIONS These results suggest that apigenin may inhibit IS-induced ER stress and expression of IL-6 and p21 proteins in HK-2 cells. It is most likely that apigenin, together with its inhibitory effect on ER stress, may also suppress the cell growth by inducing the loss of Rb phosphorylation, which was associated with the decrease in cyclin D1 expression by GSK-3β activation through the inhibition of PI3K/Akt pathway.
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Affiliation(s)
- B-J Jeon
- Department of Pathology, College of Korean Medicine, Wonkwang University, Iksan, Jeonbuk, Republic of Korea.
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Namba T, Kodama R. Avarol induces apoptosis in pancreatic ductal adenocarcinoma cells by activating PERK-eIF2α-CHOP signaling. Mar Drugs 2015; 13:2376-89. [PMID: 25894488 PMCID: PMC4413216 DOI: 10.3390/md13042376] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 03/28/2015] [Accepted: 04/08/2015] [Indexed: 01/05/2023] Open
Abstract
Avarol is a sesquiterpenoid hydroquinone with potent cytotoxicity. Although resolving endoplasmic reticulum (ER) stress is essential for intracellular homeostasis, erratic or excessive ER stress can lead to apoptosis. Here, we reported that avarol selectively induces cell death in pancreatic ductal adenocarcinomas (PDAC), which are difficult to treat owing to the availability of few chemotherapeutic agents. Analyses of the molecular mechanisms of avarol-induced apoptosis indicated upregulation of ER stress marker BiP and ER stress-dependent apoptosis inducer CHOP in PDAC cells but not in normal cells, suggesting that avarol selectively induces ER stress responses. We also showed that avarol activated the PERK–eIF2α pathway but did not affect the IRE1 and ATF6 pathways. Moreover, CHOP downregulation was significantly suppressed by avarol-induced apoptosis. Thus, the PERK–eIF2α–CHOP signaling pathway may be a novel molecular mechanism of avarol-induced apoptosis. The present data indicate that avarol has potential as a chemotherapeutic agent for PDAC and induces apoptosis by activating the PERK–eIF2α pathway.
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Affiliation(s)
- Takushi Namba
- Science Research Center, Kochi University, Kohasu, Oko-cho, Nankoku-shi, Kochi 783-8505, Japan.
| | - Rika Kodama
- Science Research Center, Kochi University, Kohasu, Oko-cho, Nankoku-shi, Kochi 783-8505, Japan.
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Wu YJ, Guo X, Li CJ, Li DQ, Zhang J, Yang Y, Kong Y, Guo H, Liu DM, Chen LM. Dipeptidyl peptidase-4 inhibitor, vildagliptin, inhibits pancreatic beta cell apoptosis in association with its effects suppressing endoplasmic reticulum stress in db/db mice. Metabolism 2015; 64:226-35. [PMID: 25195070 DOI: 10.1016/j.metabol.2014.08.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/17/2014] [Accepted: 08/12/2014] [Indexed: 12/11/2022]
Abstract
AIMS Vildagliptin promotes beta cell survival by inhibiting cell apoptosis. It has been suggested that chronic ER (endoplasmic reticulum) stress triggers beta cell apoptosis. The objective of the study is to explore whether the pro-survival effect of vildagliptin is associated with attenuation of endoplasmic reticulum stress in islets of db/db mice. METHODS Vildagliptin was orally administered to db/db mice for 6 weeks, followed by evaluation of beta cell apoptosis by caspase3 activity and TUNEL staining method. Endoplasmic reticulum stress markers were determined with quantitative RT-PCR, immunohistochemistry and immunoblot analysis. RESULTS After 6 weeks of treatment, vildagliptin treatment increased plasma active GLP-1 levels (22.63±1.19 vs. 11.69±0.44, P<0.001), inhibited beta cell apoptosis as demonstrated by lower amounts of TUNEL staining nuclei (0.37±0.03 vs. 0.55±0.03, P<0.01) as well as decreased caspase3 activity (1.48±0.11 vs. 2.67±0.13, P<0.01) in islets of diabetic mice compared with untreated diabetic group. Further, vildagliptin treatment down-regulated several genes related to endoplasmic reticulum stress including TRIB3 (tribbles homolog 3) (15.9±0.4 vs. 33.3±1.7, ×10⁻³, P<0.001), ATF-4(activating transcription factor 4) (0.83±0.06 vs. 1.42±0.02, P<0.001) and CHOP(C/EBP homologous protein) (0.07±0.01 vs. 0.16±0.01, P<0.001). CONCLUSIONS Vildagliptin promoted beta cell survival in db/db mice in association with down-regulating markers of endoplasmic reticulum stress including TRIB3, ATF-4 as well as CHOP.
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Affiliation(s)
- Yan-ju Wu
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Xin Guo
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Chun-jun Li
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Dai-qing Li
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Jie Zhang
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Yiping Yang
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Yan Kong
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Hang Guo
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - De-min Liu
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China
| | - Li-ming Chen
- Key Laboratory of Hormones and Development (Ministry of Health), Metabolic Diseases Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China.
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Ferlito M, Wang Q, Fulton WB, Colombani P, Marchionni L, Fox-Talbot K, Paolocci N, Steenbergen C. Hydrogen sulfide [corrected] increases survival during sepsis: protective effect of CHOP inhibition. J Immunol 2014; 192:1806-14. [PMID: 24403532 PMCID: PMC3946246 DOI: 10.4049/jimmunol.1300835] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Sepsis is a major cause of mortality, and dysregulation of the immune response plays a central role in this syndrome. H2S, a recently discovered gaso-transmitter, is endogenously generated by many cell types, regulating a number of physiologic processes and pathophysiologic conditions. We report that H2S increased survival after experimental sepsis induced by cecal ligation and puncture (CLP) in mice. Exogenous H2S decreased the systemic inflammatory response, reduced apoptosis in the spleen, and accelerated bacterial eradication. We found that C/EBP homologous protein 10 (CHOP), a mediator of the endoplasmic reticulum stress response, was elevated in several organs after CLP, and its expression was inhibited by H2S treatment. Using CHOP-knockout (KO) mice, we demonstrated for the first time, to our knowledge, that genetic deletion of Chop increased survival after LPS injection or CLP. CHOP-KO mice displayed diminished splenic caspase-3 activation and apoptosis, decreased cytokine production, and augmented bacterial clearance. Furthermore, septic CHOP-KO mice treated with H2S showed no additive survival benefit compared with septic CHOP-KO mice. Finally, we showed that H2S inhibited CHOP expression in macrophages by a mechanism involving Nrf2 activation. In conclusion, our findings show a protective effect of H2S treatment afforded, at least partially, by inhibition of CHOP expression. The data reveal a major negative role for the transcription factor CHOP in overall survival during sepsis and suggest a new target for clinical intervention, as well potential strategies for treatment.
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Affiliation(s)
- Marcella Ferlito
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Qihong Wang
- Department of Surgery, Division of Pediatric Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - William B Fulton
- Department of Surgery, Division of Pediatric Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Paul Colombani
- Department of Surgery, Division of Pediatric Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Luigi Marchionni
- Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Karen Fox-Talbot
- Department of Pathology, Division of Cardiovascular Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Nazareno Paolocci
- Department of Medicine, Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD
| | - Charles Steenbergen
- Department of Pathology, Division of Cardiovascular Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD
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Shen M, Wang L, Yang G, Gao L, Wang B, Guo X, Zeng C, Xu Y, Shen L, Cheng K, Xia Y, Li X, Wang H, Fan L, Wang X. Baicalin protects the cardiomyocytes from ER stress-induced apoptosis: inhibition of CHOP through induction of endothelial nitric oxide synthase. PLoS One 2014; 9:e88389. [PMID: 24520378 PMCID: PMC3919764 DOI: 10.1371/journal.pone.0088389] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 01/12/2014] [Indexed: 12/18/2022] Open
Abstract
Baicalin, the main active ingredient of the Scutellaria root, exerts anti-oxidant and anti-apoptotic effects in cardiovascular diseases. However, the therapeutic mechanism of baicalin remains unknown. Cultured neonatal rat cardiomyocytes were pre-treated with baicalin (0–50 µM) for 24 h, and subsequently treated with tunicamycin (100 ng/ml). Cell viability was detected by MTT assay, and cell damage was determined by LDH release and TUNEL assay. The expression of CHOP, JNK, caspase-3, eNOS was analyzed by western blot. NO was measured by DAF-FM staining. As a result, treatment with baicalin significantly reduced apoptosis induced by ER stress inducer tunicamycin in cardiomyocytes. Molecularly, baicalin ameliorated tunicamycin-induced ER stress by downregulation of CHOP. In addition, baicalin inverted tunicamycin-induced decreases of eNOS mRNA and protein levels, phospho eNOS and NO production through CHOP pathway. However, the protective effects of baicalin were significantly decreased in cardiomyocytes treated with L-NAME, which suppressed activation of nitric oxide synthase. In conclusion, our results implicate that baicalin could protect cardiomyocytes from ER stress-induced apoptosis via CHOP/eNOS/NO pathway, and suggest the therapeutic values of baicalin against ER stress-associated cardiomyocyte apoptosis.
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Affiliation(s)
- Mingzhi Shen
- Department of Geriatrics, Xijing Hospital, Fourth Military Medical University, Xi’an, China
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi’an, China
- Department of Cardiology, Hainan Branch of PLA General Hospital, Sanya, China
| | - Lin Wang
- Department of Geriatrics, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Guodong Yang
- Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi’an, China
| | - Lei Gao
- Department of Urology, Wuhan General Hospital, Guangzhou Command, PLA, Wuhan, China
| | - Bo Wang
- Department of Geriatrics, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Xiaowang Guo
- Department of Geriatrics, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Chao Zeng
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Yong Xu
- Department of Cardiology, Hainan Branch of PLA General Hospital, Sanya, China
| | - Liangliang Shen
- Department of Biochemistry and Molecular Biology, Fourth Military Medical University, Xi’an, China
| | - Ke Cheng
- Department of Geriatrics, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Yuesheng Xia
- Department of Geriatrics, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Xiumin Li
- Department of Geriatrics, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Haichang Wang
- Department of Cardiology, Xijing Hospital, Fourth Military Medical University, Xi’an, China
- * E-mail: (XMW); (LF); (HCW)
| | - Li Fan
- Department of Geriatric Cardiology, Chinese PLA General Hospital, Beijing, China
- * E-mail: (XMW); (LF); (HCW)
| | - Xiaoming Wang
- Department of Geriatrics, Xijing Hospital, Fourth Military Medical University, Xi’an, China
- * E-mail: (XMW); (LF); (HCW)
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12
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Rubiolo JA, López-Alonso H, Martínez P, Millán A, Cagide E, Vieytes MR, Vega FV, Botana LM. Yessotoxin induces ER-stress followed by autophagic cell death in glioma cells mediated by mTOR and BNIP3. Cell Signal 2014; 26:419-432. [PMID: 24511615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Yessotoxin at nanomolar concentrations can induce programmed cell death in different model systems. Paraptosis-like cell death induced by YTX in BC3H1 cells, which are insensitive to several caspase inhibitors,has also been reported. This makes yessotoxin of interest in the search of molecules that target cancer cells vulnerabilities when resistance to apoptosis is observed. To better understand the effect of this molecule at the molecular level on tumor cells, we conducted a transcriptomic analysis using 3 human glioma cell lines with different sensitivities to yessotoxin. We show that the toxin induces a deregulation of the lipid metabolism in glioma cells as a consequence of induction of endoplasmic reticulum stress. The endoplasmic reticulum stress in turn arrests the cell cycle and inhibits the protein synthesis. In the three cell lines used we show that YTX induces autophagy, which is involved in cell death. The sensibility of the cell lines used towards autophagic cell death was related to their doubling time, being the cell line with the lowest proliferation rate the most resistant.The involvement of mTOR and BNIP3 in the autophagy induction was also determined.
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Guo W, Ding J, Zhang A, Dai W, Liu S, Diao Z, Wang L, Han X, Liu W. The inhibitory effect of quercetin on asymmetric dimethylarginine-induced apoptosis is mediated by the endoplasmic reticulum stress pathway in glomerular endothelial cells. Int J Mol Sci 2014; 15:484-503. [PMID: 24451129 PMCID: PMC3907821 DOI: 10.3390/ijms15010484] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 12/12/2013] [Accepted: 12/16/2013] [Indexed: 01/11/2023] Open
Abstract
Asymmetric dimethylarginine (ADMA) is considered an independent mortality and cardiovascular risk factor in chronic kidney disease (CKD) patients, and contributes to the development of renal fibrosis. Quercetin (QC), a natural component of foods, protects against renal injury. Here, we explored the possible mechanisms that are responsible for ADMA-induced renal fibrosis and the protective effect of QC. We found that ADMA treatment activated the endoplasmic reticulum (ER) stress sensor proteins phosphorylated protein kinase RNA-activated-like ER kinase (PERK) and inositol requiring-1α (IRE1), which correspondingly induced C/EBP homologous protein (CHOP) expression and phosphorylated c-Jun N-terminal kinase (JNK) phosphorylation in glomerular endothelial cells (GEnCs). Following this, ADMA promoted ER stress-induced apoptosis and resulted in transforming growth factor β (TGF-β) expression in GEnCs. SP600125, an inhibitor of JNK, and CHOP siRNA protected against ADMA-induced cell apoptosis and TGF-β expression. QC prevented ADMA-induced PERK and IRE1 apoptotic ER stress pathway activation. Also, ADMA-induced GEnCs apoptosis and TGF-β expression was reduced by QC. Overexpression of CHOP blocked QC-mediated protection from apoptosis in ER stressed cells. Overall, these observations indicate that ADMA may induce GEnCs apoptosis and TGF-β expression by targeting the PERK-CHOP and IRE1-JNK pathway. In addition, drugs such as QC targeting ER stress may hold great promise for the development of novel therapies against ADMA-induced renal fibrosis.
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Affiliation(s)
- Weikang Guo
- Department of Nephrology, Beijing Friendship Hospital, Faculty of Kidney Diseases, Capital Medical University, Beijing 100050, China.
| | - Jiaxiang Ding
- Department of Nephrology, Beijing Friendship Hospital, Faculty of Kidney Diseases, Capital Medical University, Beijing 100050, China.
| | - Aihua Zhang
- Department of Nephrology, Beijing Friendship Hospital, Faculty of Kidney Diseases, Capital Medical University, Beijing 100050, China.
| | - Wendi Dai
- Department of Nephrology, Beijing Friendship Hospital, Faculty of Kidney Diseases, Capital Medical University, Beijing 100050, China.
| | - Sha Liu
- Department of Nephrology, Beijing Friendship Hospital, Faculty of Kidney Diseases, Capital Medical University, Beijing 100050, China.
| | - Zongli Diao
- Department of Nephrology, Beijing Friendship Hospital, Faculty of Kidney Diseases, Capital Medical University, Beijing 100050, China.
| | - Liyan Wang
- Department of Nephrology, Beijing Friendship Hospital, Faculty of Kidney Diseases, Capital Medical University, Beijing 100050, China.
| | - Xue Han
- Department of Nephrology, Beijing Friendship Hospital, Faculty of Kidney Diseases, Capital Medical University, Beijing 100050, China.
| | - Wenhu Liu
- Department of Nephrology, Beijing Friendship Hospital, Faculty of Kidney Diseases, Capital Medical University, Beijing 100050, China.
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Marwarha G, Raza S, Prasanthi JRP, Ghribi O. Gadd153 and NF-κB crosstalk regulates 27-hydroxycholesterol-induced increase in BACE1 and β-amyloid production in human neuroblastoma SH-SY5Y cells. PLoS One 2013; 8:e70773. [PMID: 23951005 PMCID: PMC3739769 DOI: 10.1371/journal.pone.0070773] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 06/21/2013] [Indexed: 11/19/2022] Open
Abstract
β-amyloid (Aβ) peptide, accumulation of which is a culprit for Alzheimer's disease (AD), is derived from the initial cleavage of amyloid precursor protein by the aspartyl protease BACE1. Identification of cellular mechanisms that regulate BACE1 production is of high relevance to the search for potential disease-modifying therapies that inhibit BACE1 to reduce Aβ accumulation and AD progression. In the present study, we show that the cholesterol oxidation product 27-hydroxycholesterol (27-OHC) increases BACE1 and Aβ levels in human neuroblastoma SH-SY5Y cells. This increase in BACE1 involves a crosstalk between the two transcription factors NF-κB and the endoplasmic reticulum stress marker, the growth arrest and DNA damage induced gene-153 (gadd153, also called CHOP). We specifically show that 27-OHC induces a substantial increase in NF-κB binding to the BACE1 promoter and subsequent increase in BACE1 transcription and Aβ production. The NF-κB inhibitor, sc514, significantly attenuated the 27-OHC-induced increase in NF-κB-mediated BACE1 expression and Aβ genesis. We further show that the 27-OHC-induced NF-κB activation and increased NF-κB-mediated BACE1 expression is contingent on the increased activation of gadd153. Silencing gadd153 expression with siRNA alleviated the 27-OHC-induced increase in NF-κB activation, NF-κB binding to the BACE1 promoter, and subsequent increase in BACE1 transcription and Aβ production. We also show that increased levels of BACE1 in the triple transgenic mouse model for AD is preceded by gadd153 and NF-κB activation. In summary, our study demonstrates that gadd153 and NF-κB work in concert to regulate BACE1 expression. Agents that inhibit gadd153 activation and subsequent interaction with NF-κB might be promising targets to reduce BACE1 and Aβ overproduction and may ultimately serve as disease-modifying treatments for AD.
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Affiliation(s)
- Gurdeep Marwarha
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
| | - Shaneabbas Raza
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
| | - Jaya R. P. Prasanthi
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
| | - Othman Ghribi
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, United States of America
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15
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Zhu H, Qian J, Wang W, Yan Q, Xu Y, Jiang Y, Zhang L, Lu F, Hu W, Zhang X, Wang F, Sun X. RNA interference of GADD153 protects photoreceptors from endoplasmic reticulum stress-mediated apoptosis after retinal detachment. PLoS One 2013; 8:e59339. [PMID: 23555658 PMCID: PMC3612068 DOI: 10.1371/journal.pone.0059339] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 02/13/2013] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Apoptosis of photoreceptors plays a critical role in the vision loss caused by retinal detachment (RD). Pharmacologic inhibition of photoreceptor cell death may prevent RD. This study investigated the role of GADD153 that participates in endoplasmic reticulum (ER) stress-mediated apoptosis of photoreceptor cells after RD. METHODS Retinal detachment was created in Wistar rats by subretinal injection of hyaluronic acid. The rats were then randomly divided into four groups: normal control group, RD group, GADD153 RNAi group and vehicle group. RNA interference of GADD153 was performed using short hairpin RNA (shRNA). Expressions of GADD153 mRNA and protein were examined by RT-PCR and Western blotting analysis, respectively. GADD153 protein distribution in the retinal cells was observed using immunofluorescence confocal laser scanning microscopy. Apoptosis of retinal cells was determined by TdT-mediated fluorescein-16-dUTP nick-end labeling (TUNEL) assay. RESULTS Lentivirus GADD153 shRNA with the most effective silencing effect was chosen for in vivo animal study and was successfully delivered into the retinal tissues. GADD153 mRNA and protein expressions in GADD153 RNAi group were significantly lower than those in the RD group. Silencing of GADD153 by RNAi protected photoreceptors from ER stress-induced apoptosis. CONCLUSION ER stress-mediated pathway is involved in photoreceptor cell apoptosis after RD. GADD153 is a key regulatory molecule regulating ER-stress pathways and plays a crucial role in the apoptosis of photoreceptor cells after RD.
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Affiliation(s)
- Hong Zhu
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
- Department of Ophthalmology, No.3 People’s Hospital Affiliated to Shanghai JiaoTong University School of Medicine, Shanghai, China
| | - Jin Qian
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Wenqiu Wang
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Quan Yan
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Ying Xu
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Yuan Jiang
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Lei Zhang
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Fengqing Lu
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Weiting Hu
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Xi Zhang
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
- Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
| | - Fenghua Wang
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
- Shanghai Key Laboratory of Fundus Disease, Shanghai, China
- * E-mail: (XS); (FW)
| | - Xiaodong Sun
- Department of Ophthalmology, Shanghai First People’s Hospital, School of Medicine, Shanghai JiaoTong University, Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
- Eye Research Institute of Shanghai JiaoTong University, Shanghai, China
- * E-mail: (XS); (FW)
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16
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Her GM, Pai WY, Lai CY, Hsieh YW, Pang HW. Ubiquitous transcription factor YY1 promotes zebrafish liver steatosis and lipotoxicity by inhibiting CHOP-10 expression. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:1037-51. [PMID: 23416188 DOI: 10.1016/j.bbalip.2013.02.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 02/04/2013] [Accepted: 02/06/2013] [Indexed: 02/06/2023]
Abstract
The ubiquitous transcription factor Yin Yang 1 (YY1) is known to have diverse and complex cellular functions. Although relevant literature has reported that YY1 expression can induce the down-regulation of C/EBP homologous protein 10 (CHOP-10) and then allow the transactivation of certain transcription factors required for lipogenesis, similar properties of YY1 are poorly understood in animal model systems. In this study, we demonstrate hepatic lipid accumulation in YY1 transgenic zebrafish (GY). Oil-red staining cells were predominantly increased in the livers of both GY larvae and adults, indicating that YY1 functionally promoted lipid accumulation in GY livers. Molecular analysis revealed that YY1 over-expression contributed to the accumulation of hepatic triglycerides (TGs) by inhibiting CHOP-10 expression in the juvenile GY and 3 other fish cell lines; the decreased CHOP-10 expression then induced the transactivation of C/EBP-α and PPAR-γ expression. CHOP-10 morpholino (MO)-injected and rosiglitazone-treated G-liver larvae showed liver steatosis by transactivating PPAR-γ. PPAR-γ MO-injected, and GW9662- and astaxanthin-treated GY larvae showed no liver steatosis by inhibiting PPAR-γ. Moreover, a fatty acid (FA) accumulation and a TG decrease were found in the liver of aged GY, leading to the induction of FA-oxidizing systems that increased hepatic oxidative stress and liver damage. This study is the first to examine YY1 as a potential stimulator for GY liver steatosis and lipotoxicity.
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Affiliation(s)
- Guor Mour Her
- Institute of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Taiwan.
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17
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Chen L, Ren F, Zhang H, Wen T, Piao Z, Zhou L, Zheng S, Zhang J, Chen Y, Han Y, Duan Z, Ma Y. Inhibition of glycogen synthase kinase 3β ameliorates D-GalN/LPS-induced liver injury by reducing endoplasmic reticulum stress-triggered apoptosis. PLoS One 2012; 7:e45202. [PMID: 23028846 PMCID: PMC3461002 DOI: 10.1371/journal.pone.0045202] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 08/17/2012] [Indexed: 01/22/2023] Open
Abstract
Background Glycogen synthase kinase 3β(GSK3β) is a ubiquitous serine-threonine protein kinase that participates in numerous cellular processes and disease pathophysiology. We aimed to determine therapeutic potential of GSK3β inhibition and its mechanism in a well-characterized model of lipopolysaccharide (LPS)-induced model of acute liver failure (ALF). Methodology In a murine ALF model induced by D-GalN(700 mg/kg)/LPS(10 µg/kg), we analyzed GSK3β mechanisms using a specific chemical inhibitor, SB216763, and detected the role of endoplasmic reticulum stress (ERS). Mice were administered SB216763 at 2 h before or after D-GalN/LPS injection, respectively, and then sacrificed 6 h after D-GalN/LPS treatment to evaluate its prophylactic and therapeutic function. The lethality rate, liver damage, ERS, cytokine expression, MAP kinase, hepatocyte apoptosis and expression of TLR 4 were evaluated, respectively. Whether the inhibition of GSK3β activation protected hepatocyte from ERS-induced apoptosis was investigated in vitro. Principal Findings GSK3β became quickly activated (dephosphorylated) upon D-GalN/LPS exposure. Administration of SB216763 not only ameliorated liver injury, as evidenced by reduced transaminase levels, and well-preserved liver architecture, but also decreased lethality. Moreover, GSK3β inhibition resulted in down-regulation of pro-apoptotic proteins C/EBP–homologous protein(CHOP) and caspase-12, which are related to ERS. To further demonstrate the role of ERS, we found that GSK3β inhibition protected hepatocyte from ERS-induced cell death. GSK3β inhibition down-regulated the MAPK pathways, reduced expression of inflammatory cytokines and decreased expression of TLR4. Conclusions Our findings demonstrate the key function of GSK3β signaling in the pathophysiology of ALF, especially in regulating the ERS, and provide a rationale for targeting GSK3β as a potential therapeutic strategy to ameliorate ALF.
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Affiliation(s)
- Liyan Chen
- The 2nd Department of Infectious Diseases, the 2nd Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province, People’s Republic of China
| | - Feng Ren
- Beijing Institute of Liver Diseases, Capital Medical University, Beijing, People’s Republic of China
- Beijing Artificial Liver Treatment & Training Center, Beijing Youan Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Haiyan Zhang
- Beijing Institute of Liver Diseases, Capital Medical University, Beijing, People’s Republic of China
| | - Tao Wen
- Beijing Institute of Liver Diseases, Capital Medical University, Beijing, People’s Republic of China
| | - Zhengfu Piao
- Beijing Institute of Liver Diseases, Capital Medical University, Beijing, People’s Republic of China
| | - Li Zhou
- Beijing Artificial Liver Treatment & Training Center, Beijing Youan Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Sujun Zheng
- Beijing Artificial Liver Treatment & Training Center, Beijing Youan Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Jing Zhang
- Beijing Artificial Liver Treatment & Training Center, Beijing Youan Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Yu Chen
- Beijing Artificial Liver Treatment & Training Center, Beijing Youan Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Yuanping Han
- Beijing Artificial Liver Treatment & Training Center, Beijing Youan Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Zhongping Duan
- Beijing Artificial Liver Treatment & Training Center, Beijing Youan Hospital, Capital Medical University, Beijing, People’s Republic of China
| | - Yingji Ma
- The Department of Infectious Diseases, The 4th Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province, People’s Republic of China
- * E-mail:
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18
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Chiu SC, Chen SP, Huang SY, Wang MJ, Lin SZ, Harn HJ, Pang CY. Induction of apoptosis coupled to endoplasmic reticulum stress in human prostate cancer cells by n-butylidenephthalide. PLoS One 2012; 7:e33742. [PMID: 22470469 PMCID: PMC3314677 DOI: 10.1371/journal.pone.0033742] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 02/16/2012] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND N-butylidenephthalide (BP) exhibits antitumor effect in a variety of cancer cell lines. The objective of this study was to obtain additional insights into the mechanisms involved in BP induced cell death in human prostate cancer cells. METHODS/PRINCIPAL FINDINGS Two human prostate cancer cell lines, PC-3 and LNCaP, were treated with BP, and subsequently evaluated for their viability and cell cycle profiles. BP caused cell cycle arrest and cell death in both cell lines. The G0/G1 phase arrest was correlated with increase levels of CDK inhibitors (p16, p21 and p27) and decrease of the checkpoint proteins. To determine the mechanisms of BP-induced growth arrest and cell death in prostate cancer cell lines, we performed a microarray study to identify alterations in gene expression induced by BP in the LNCaP cells. Several BP-induced genes, including the GADD153/CHOP, an endoplasmic reticulum stress (ER stress)-regulated gene, were identified. BP-induced ER stress was evidenced by increased expression of the downstream molecules GRP78/BiP, IRE1-α and GADD153/CHOP in both cell lines. Blockage of IRE1-α or GADD153/CHOP expression by siRNA significantly reduced BP-induced cell death in LNCaP cells. Furthermore, blockage of JNK1/2 signaling by JNK siRNA resulted in decreased expression of IRE1-α and GADD153/CHOP genes, implicating that BP-induced ER stress may be elicited via JNK1/2 signaling in prostate cancer cells. BP also suppressed LNCaP xenograft tumor growth in NOD-SCID mice. It caused 68% reduction in tumor volume after 18 days of treatment. CONCLUSIONS Our results suggest that BP can cause G0/G1 phase arrest in prostate cancer cells and its cytotoxicity is mediated by ER stress induction. Thus, BP may serve as an anticancer agent by inducing ER stress in prostate cancer.
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Affiliation(s)
- Sheng-Chun Chiu
- Department of Medical Research, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
| | - Shee-Ping Chen
- Tzu Chi Stem Cells Center, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
| | - Sung-Ying Huang
- Department of Ophthalmology, Mackay Memorial Hospital, Hsinchu, Taiwan
| | - Mei-Jen Wang
- Department of Medical Research, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
| | - Shinn-Zong Lin
- Center for Neuropsychiatry, China Medical University Hospital, Taichung, Taiwan
| | - Horng-Jyh Harn
- Department of Pathology, China Medical University Hospital, Taichung, Taiwan
| | - Cheng-Yoong Pang
- Department of Medical Research, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
- Institute of Medical Sciences, School of Medicine, Tzu Chi University, Hualien, Taiwan
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Oshitari T, Yoshida-Hata N, Yamamoto S. Effect of neurotrophin-4 on endoplasmic reticulum stress-related neuronal apoptosis in diabetic and high glucose exposed rat retinas. Neurosci Lett 2011; 501:102-6. [PMID: 21767604 DOI: 10.1016/j.neulet.2011.06.057] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2011] [Revised: 06/10/2011] [Accepted: 06/28/2011] [Indexed: 02/02/2023]
Abstract
The purpose of this study was to investigate the effect of NT-4 on the endoplasmic reticulum (ER) stress-related apoptosis of retinal neurons of isolated retinas. The retinas were isolated from normal and diabetic rats, and the normal retinas were exposed to high glucose (HG). Our results showed that the number of TUNEL-positive, and PERK- and CHOP-positive cells was significantly higher in diabetic and HG exposed retinas than in normal retinas. In diabetic and HG exposed retinas supplemented with NT-4, the number of TUNEL-positive, and PERK- and CHOP-positive cells was significantly lower than in retinas without NT-4. The neuroprotective effect of NT-4 on retinas cultured under diabetic stress was correlated with the suppression in the expression of PERK and CHOP, ER stress-related factors.
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Affiliation(s)
- Toshiyuki Oshitari
- Department of Ophthalmology and Visual Science, Chiba University Graduate School of Medicine, Inohana 1-8-1, Chuo-ku, Chiba 260-8670, Japan.
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20
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Chung H, Chung HY, Bae CW, Kim CJ, Park S. Ghrelin suppresses tunicamycin- or thapsigargin-triggered endoplasmic reticulum stress-mediated apoptosis in primary cultured rat cortical neuronal cells. Endocr J 2011; 58:409-20. [PMID: 21490406 DOI: 10.1507/endocrj.k10e-396] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Ghrelin functions as a neuroprotective agent and rescues neurons from various insults. However, the molecular mechanisms underlying ghrelin neuroprotection remains to be elucidated. An accumulation of unfolded proteins in the endoplasmic reticulum (ER) leads to ER stress and then induces ER stress-mediated cell death. Here, we report that acylated ghrelin inhibited tunicamycin- or thapsigargin-triggered ER stress-induced apoptotic cell death in primary rat cortical neurons. An analysis using a specific inhibitor of phosphatidylinositol-3-kinase (PI3K), LY294002, showed that ghrelin prevented apoptosis via the activation of PI3K signaling pathway. Ghrelin suppressed tunicamycin- or thapsigargin-induced upregulation and nuclear translocation of C/EBP homologous protein (CHOP). Ghrelin also inhibited tunicamycin or thapsigargin induction of PRK-like ER kinase (PERK), eukaryotic translation initiation factor-2α (eIF2α) and activating transcription factor (ATF) 4. Exposure of cells to tunicamycin or thapsigargin resulted in nuclear translocation of forkhead box protein O1 (Foxo1), which was reduced by pretreatment with ghrelin. The protective effect of ghrelin was accompanied by an increased phosphorylation of Akt and glycogen synthase kinase (GSK)-3β. Furthermore, ghrelin phosphorylated and inactivated pro-apoptotic BAD and Foxo1. In addition, phospho-Akt was translocated to the nucleus in response to ghrelin and PI3K inhibition by LY294002 prevented ghrelin-induced effect on phospho-Akt localization. Our study suggests that suppression of CHOP activation via the inhibition of PERK/eIF2α/ATF4 pathway and prevention of Foxo1 activation and nuclear translocation may contribute to ghrelin-mediated neuroprotection during ER stress responses. Our data also suggest that PI3K/Akt-mediated inactivation of GSK-3β, BAD and Foxo1 may be associated with the anti-apoptotic effect of ghrelin.
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Affiliation(s)
- Hyunju Chung
- Department of Core Research Laboratory, Clinical Research Institute, The East-West Neo Medical Center, School of Medicine, Kyung Hee University, Gangdong-gu, Seoul, Korea
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Gu X, Li K, Laybutt DR, He ML, Zhao HL, Chan JCN, Xu G. Bip overexpression, but not CHOP inhibition, attenuates fatty-acid-induced endoplasmic reticulum stress and apoptosis in HepG2 liver cells. Life Sci 2010; 87:724-32. [PMID: 20970436 DOI: 10.1016/j.lfs.2010.10.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 09/30/2010] [Accepted: 10/11/2010] [Indexed: 01/12/2023]
Abstract
AIMS In this study we investigated whether attenuation of endoplasmic reticulum stress (ER stress) could protect HepG2 cells from free fatty acid (FFA)-induced apoptosis. MAIN METHODS Human liver cell line HepG2 cells were exposed to Sodium Palmitate (Pa) or Sodium Oleate (Ol). Apoptosis and ER stress of HepG2 cells were analyzed with flow cytometry, real-time RT-PCR and Western Blotting. An expression plasmid encoding for the ER chaperone immunoglobulin heavy chain-binding protein (Bip) was transfected into HepG2 cells to attenuate ER stress. Small interfering RNA siCHOP was used to knockdown the expression of C/EBP Homologous Protein (CHOP) in HepG2. KEY FINDINGS Pa led to cytotoxicity and apoptosis in HepG2 cells in a dose-dependent pattern and also induced ER stress indicated by increased phosphorylation of eIF2α, upregulation of IRE1α and CHOP. Bip expression levels were slightly down regulated after Pa treatment. The unsaturated fatty acid, Ol, induced neither apoptosis nor ER stress in HepG2 cells. Overexpression of Bip attenuated Pa-induced ER stress and led to a significant reduction in Pa-mediated apoptosis, indicating a requirement of ER stress for lipotoxicity in liver cells. siRNA-mediated reduction of CHOP did not protect against Pa-induced apoptosis. SIGNIFICANCE While ER stress makes a necessary contribution to palmitate cytotoxicity, inhibition of CHOP alone is not sufficient to prevent palmitate-induced apoptosis. Our findings could advance the detailed understanding on the mechanism of high fatty acid (FFA)-induced apoptosis.
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Affiliation(s)
- Xuemei Gu
- Department of Medicine and Therapeutics, The Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, China
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Hsieh WC, Hsu PC, Liao YF, Young ST, Wang ZW, Lin CL, Tsay GJ, Lee H, Hung HC, Liu GY. Overexpression of ornithine decarboxylase suppresses thapsigargin-induced apoptosis. Mol Cells 2010; 30:311-8. [PMID: 20814750 DOI: 10.1007/s10059-010-0120-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 07/16/2010] [Accepted: 07/20/2010] [Indexed: 12/13/2022] Open
Abstract
Ornithine decarboxylase (ODC), the key enzyme of polyamine biosynthesis, has paradoxical roles in apoptosis. Our published papers show overexpression of ODC prevents the apoptosis induced by many cytotoxic drugs. Thapsigargin (TG) is an inhibitor of the sarcoplasmic/endoplasmic reticulum (ER) Ca(2+) ATPase (SERCA) pumps and causes ER stress-induced apoptosis. We used ODC overexpressing cell lines to examine whether overexpression of ODC inhibits TG-induced apoptosis. Our results indicated overexpression of ODC attenuated TG-induced apoptosis. Overexpression of ODC blocked procaspase-4 cleavage and phosphorylation of protein kinase-like ER-resident kinase (PERK), triggered by TG. It also attenuated the increase in CAAT/enhancer binding protein homologous protein (CHOP). Cells with overexpressed ODC had greater Bcl-2 expression. Overexpression of ODC preserved the expression of Bcl-2, inhibited the increase in Bak and stabilized mitochondrial membrane potential without the influences of TG. Cytochrome c release and down-stream caspase activation were blocked. That is, overexpression of ODC inhibits the mitochondria-mediated apoptotic pathway, induced by TG. Finally, overexpression of ODC maintains the protein and mRNA expression of SERCA. In conclusion, overexpression of ODC suppresses TG-induced apoptosis by blocking caspase-4 activation and PERK phosphorylation, attenuating CHOP expression and inhibiting the mitochondria-mediated apoptotic pathway.
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Affiliation(s)
- Wei-Chung Hsieh
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan, ROC
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Ariyama Y, Tanaka Y, Shimizu H, Shimomura K, Okada S, Saito T, Yamada E, Oyadomari S, Mori M, Mori M. The role of CHOP messenger RNA expression in the link between oxidative stress and apoptosis. Metabolism 2008; 57:1625-35. [PMID: 19013284 DOI: 10.1016/j.metabol.2008.06.019] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Accepted: 06/09/2008] [Indexed: 12/20/2022]
Abstract
Low expression of antioxidant enzymes makes pancreatic beta-cells susceptible to cell damage by oxidative stress. Pancreatic beta-cell loss caused by endoplasmic reticulum stress is associated with the onset of diabetes mellitus. The present studies were undertaken to investigate a possible involvement of proapoptotic gene CHOP in pancreatic beta-cells damage by oxidative stress. The induction of CHOP messenger RNA and apoptosis were investigated in betaHC-9 cells after the oxidative stress by hydrogen peroxide and ribose. Latter was examined after the suppression of CHOP by small interfering RNA. For in vivo study, the pancreatic beta-cells were examined in CHOP-knockout (KO) mice after multiple low-dose streptozotocin (MLDS) administration. In betaHC-9 cells, both hydrogen peroxide and ribose obviously increased apoptotic cells, accompanied with enhanced CHOP messenger RNA expression. However, the number of apoptotic cells by those stimulations was significantly reduced by the addition of small interfering RNA against CHOP. In vivo study also showed that CHOP-KO mice were less susceptible to diabetes after MLDS administration. Although the oxidative stress marker level was similar to that of MLDS-treated wild type, the pancreatic beta-cell area was maintained in CHOP-KO mice. The present studies showed that CHOP should be important in pancreatic beta-cell injury by oxidative stress and indicate that CHOP may play a role in the development of pancreatic beta-cell damage on the onset of diabetes mellitus.
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Affiliation(s)
- Yasuyo Ariyama
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
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Ohoka N, Hattori T, Kitagawa M, Onozaki K, Hayashi H. Critical and functional regulation of CHOP (C/EBP homologous protein) through the N-terminal portion. J Biol Chem 2007; 282:35687-94. [PMID: 17872950 DOI: 10.1074/jbc.m703735200] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
C/EBP homologous protein (CHOP) is an endoplasmic reticulum stress-inducible protein that plays a critical role in the regulation of programmed cell death; however, the regulation of its function has not been well characterized. We have previously demonstrated that CHOP is regulated by the ubiquitin-proteasome system. In this study, during the process of clarifying the mechanism of the degradation of CHOP, we identified a novel regulation domain of CHOP in its N-terminal portion that is involved in various regulations and functions. The CHOP N-terminal domain is necessary not only for protein degradation but also for its transactivity and interaction with p300. In addition, trichostatin A, a histone deacetylase inhibitor, repressed the degradation of CHOP protein via the N-terminal domain. TRB3, a mammalian tribbles homolog that functions as a repressor of CHOP, also interacted with CHOP via the N-terminal portion and significantly blocked the association of p300 with CHOP. These results suggest that the N-terminal portion of CHOP plays a crucial role in its functional regulation and enable us to identify a novel function of TRB3 as an intracellular antagonist of the p300-binding domain of CHOP.
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Affiliation(s)
- Nobumichi Ohoka
- Department of Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
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Wei W, Yang H, Menconi M, Cao P, Chamberlain CE, Hasselgren PO. Treatment of cultured myotubes with the proteasome inhibitor β-lactone increases the expression of the transcription factor C/EBPβ. Am J Physiol Cell Physiol 2007; 292:C216-26. [PMID: 16987992 DOI: 10.1152/ajpcell.00282.2006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of the proteasome in the regulation of cellular levels of the transcription factor CCAAT/enhancer-binding protein β (C/EBPβ) is poorly understood. We tested the hypothesis that C/EBPβ levels in cultured myotubes are regulated, at least in part, by proteasome activity. Treatment of cultured L6 myotubes, a rat skeletal muscle cell line, with the specific proteasome inhibitor β-lactone resulted in increased nuclear levels of C/EBPβ as determined by Western blotting and immunofluorescent detection. This effect of β-lactone reflected inhibited degradation of C/EBPβ. Surprisingly, the increased C/EBPβ levels in β-lactone-treated myotubes did not result in increased DNA-binding activity. In additional experiments, treatment of the myotubes with β-lactone resulted in increased nuclear levels of growth arrest DNA damage/C/EBP homologous protein (Gadd153/CHOP), a dominant-negative member of the C/EBP family that can form heterodimers with other members of the C/EBP family and block DNA binding. Coimmunoprecipitation and immunofluorescent detection provided evidence that C/EBPβ and Gadd153/CHOP interacted and colocalized in the nuclei of the β-lactone-treated myotubes. When Gadd153/CHOP expression was downregulated by transfection of myotubes with siRNA targeting Gadd153/CHOP, C/EBPβ DNA-binding activity was restored in β-lactone-treated myotubes. The results suggest that C/EBPβ is degraded by a proteasome-dependent mechanism in skeletal muscle cells and that Gadd153/CHOP can interact with C/EBPβ and block its DNA-binding activity. The observations are important because they increase the understanding of the complex regulation of the expression and activity of C/EBPβ in skeletal muscle.
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Affiliation(s)
- Wei Wei
- Department of Surgery, Beth Israel Deaconess Medical Center, 330 Brookline Avenue ST 919, Boston, MA 02215, USA
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