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Kilbas PO, Can ND, Kizilboga T, Ezberci F, Doganay HL, Arisan ED, Dinler Doganay G. CRISPR/Cas9-mediated Bag-1 knockout increased mesenchymal characteristics of MCF-7 cells via Akt hyperactivation-mediated actin cytoskeleton remodeling. PLoS One 2022; 17:e0261062. [PMID: 34995286 PMCID: PMC8741009 DOI: 10.1371/journal.pone.0261062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 11/23/2021] [Indexed: 11/18/2022] Open
Abstract
Bag-1 protein is a crucial target in cancer to increase the survival and proliferation of cells. The Bag-1 expression is significantly upregulated in primary and metastatic cancer patients compared to normal breast tissue. Overexpression of Bag-1 decreases the efficiency of conventional chemotherapeutic drugs, whereas Bag-1 silencing enhances the apoptotic efficiency of therapeutics, mostly in hormone-positive breast cancer subtypes. In this study, we generated stable Bag-1 knockout (KO) MCF-7 breast cancer cells to monitor stress-mediated cellular alterations in comparison to wild type (wt) and Bag-1 overexpressing (Bag-1 OE) MCF-7 cells. Validation and characterization studies of Bag-1 KO cells showed different cellular morphology with hyperactive Akt signaling, which caused stress-mediated actin reorganization, focal adhesion decrease and led to mesenchymal characteristics in MCF-7 cells. A potent Akt inhibitor, MK-2206, suppressed mesenchymal transition in Bag-1 KO cells. Similar results were obtained following the recovery of Bag-1 isoforms (Bag-1S, M, or L) in Bag-1 KO cells. The findings of this study emphasized that Bag-1 is a mediator of actin-mediated cytoskeleton organization through regulating Akt activation.
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Affiliation(s)
- Pelin Ozfiliz Kilbas
- Department of Molecular Biology Genetics and Biotechnology, Istanbul Technical University, Istanbul, Turkey
- Department of Molecular Biology and Genetics, Istanbul Kultur University, Istanbul, Turkey
| | - Nisan Denizce Can
- Department of Molecular Biology Genetics and Biotechnology, Istanbul Technical University, Istanbul, Turkey
| | - Tugba Kizilboga
- Department of Molecular Biology Genetics and Biotechnology, Istanbul Technical University, Istanbul, Turkey
| | - Fikret Ezberci
- Department of General Surgery, Umraniye Teaching and Research Hospital, Istanbul, Turkey
| | - Hamdi Levent Doganay
- Genomic Laboratory (GLAB), Umraniye Teaching And Research Hospital, University of Health Sciences, Istanbul, Turkey
| | - Elif Damla Arisan
- Institute of Biotechnology, Gebze Technical University, Kocaeli, Turkey
- * E-mail: (EDA); (GDD)
| | - Gizem Dinler Doganay
- Department of Molecular Biology Genetics and Biotechnology, Istanbul Technical University, Istanbul, Turkey
- * E-mail: (EDA); (GDD)
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Wang M, Wei J, Ji T, Zang K. miRNA-770-5p expression is upregulated in patients with type 2 diabetes and miRNA-770-5p knockdown protects pancreatic β-cell function via targeting BAG5 expression. Exp Ther Med 2021; 22:664. [PMID: 33986829 PMCID: PMC8112148 DOI: 10.3892/etm.2021.10096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 10/26/2020] [Indexed: 11/06/2022] Open
Abstract
MicroRNA (miR)-770-5p expression is increased in patients with type 2 diabetes mellitus (T2DM) compared with healthy controls; however, the roles and molecular mechanism underlying miR-770-5p in T2DM are not completely understood. In the present study, the reverse transcription-quantitative PCR (RT-qPCR) results indicated that miR-770-5p expression was significantly increased and Bcl-2 associated athanogene 5 (BAG5) expression was significantly decreased in the serum of patients with T2DM compared with healthy volunteers. TargetScan and a dual luciferase reporter gene system were used to predict and verify BAG5 as a target gene of miR-770-5p. Additionally, the RT-qPCR results demonstrated that miR-770-5p expression was significantly increased and BAG5 expression was significantly decreased in uric acid (UA)-treated Min6 cells compared with control cells. Min6 cells were transfected with miR-770-5p inhibitor and BAG5-small interfering (si)RNA to alter expression levels. The results indicated that miR-770-5p negatively regulated BAG5. The effect of miR-770-5p knockdown on UA-induced pancreatic β-cell damage and dysfunction was subsequently assessed. Min6 cells were transfected with miR-770-5p inhibitor or miR-770-5p inhibitor + BAG5-siRNA for 48 h, followed by treatment with or without 5 mg/dl UA for 24 h. Cell viability, apoptosis, apoptosis-related factor expression levels and insulin secretion were assessed. The results demonstrated that UA treatment significantly reduced cell viability, increased cell apoptosis and reduced insulin secretion in Min6 cells compared with the control group. miR-770-5p inhibitor significantly attenuated UA-induced injury and dysfunction of Min6 cells, whereas BAG5 knockdown abolished the protective effects of miR-770-5p inhibitor on UA-damaged Min6 cells. In conclusion, miR-770-5p was highly expressed in the serum of patients with T2DM compared with healthy volunteers. In UA-treated pancreatic β-cells, compared with the inhibitor control group, miR-770-5p knockdown regulated the expression of apoptosis-related genes, increased cell viability, inhibited cell apoptosis and increased insulin secretion by targeting BAG5. Therefore, the present study suggested that miR-770-5p inhibitor may serve a protective role in T2DM.
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Affiliation(s)
- Min Wang
- Department of Critical Care Medicine, The First Affiliated Huai'an People's Hospital of Nanjing Medical University, Huai'an, Jiangsu 223300, P.R. China
| | - Jilou Wei
- Department of Critical Care Medicine, The First Affiliated Huai'an People's Hospital of Nanjing Medical University, Huai'an, Jiangsu 223300, P.R. China
| | - Ting Ji
- Department of Critical Care Medicine, The First Affiliated Huai'an People's Hospital of Nanjing Medical University, Huai'an, Jiangsu 223300, P.R. China
| | - Kui Zang
- Department of Critical Care Medicine, The First Affiliated Huai'an People's Hospital of Nanjing Medical University, Huai'an, Jiangsu 223300, P.R. China
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Duggan MR, Mohseni Ahooyi T, Parikh V, Khalili K. Neuromodulation of BAG co-chaperones by HIV-1 viral proteins and H 2O 2: implications for HIV-associated neurological disorders. Cell Death Discov 2021; 7:60. [PMID: 33771978 PMCID: PMC7997901 DOI: 10.1038/s41420-021-00424-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 01/04/2021] [Accepted: 01/30/2021] [Indexed: 11/08/2022] Open
Abstract
Despite increasing numbers of aged individuals living with HIV, the mechanisms underlying HIV-associated neurological disorders (HANDs) remain elusive. As HIV-1 pathogenesis and aging are characterized by oxidative stress as well as altered protein quality control (PQC), reactive oxygen species (ROS) themselves might constitute a molecular mediator of neuronal PQC by modulating BCL-2 associated athanogene (BAG) family members. Present results reveal H2O2 replicated and exacerbated a reduction in neuronal BAG3 induced by the expression of HIV-1 viral proteins (i.e., Tat and Nef), while also causing an upregulation of BAG1. Such a reciprocal regulation of BAG3 and BAG1 levels was also indicated in two animal models of HIV, the doxycycline-inducible Tat (iTat) and the Tg26 mouse. Inhibiting oxidative stress via antioxidants in primary culture was capable of partially preserving neuronal BAG3 levels as well as electrophysiological functioning otherwise altered by HIV-1 viral proteins. Current findings indicate HIV-1 viral proteins and H2O2 may mediate neuronal PQC by exerting synergistic effects on complementary BAG family members, and suggest novel therapeutic targets for the aging HIV-1 population.
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Affiliation(s)
- Michael R Duggan
- Department of Neuroscience, Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, 7th Floor, Philadelphia, PA, 19140, USA
- Department of Psychology, College of Liberal Arts at Temple University, 1701 N 13th Street, 9th Floor, Philadelphia, PA, 19122, USA
| | - Taha Mohseni Ahooyi
- Department of Neuroscience, Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, 7th Floor, Philadelphia, PA, 19140, USA
| | - Vinay Parikh
- Department of Psychology, College of Liberal Arts at Temple University, 1701 N 13th Street, 9th Floor, Philadelphia, PA, 19122, USA
| | - Kamel Khalili
- Department of Neuroscience, Center for Neurovirology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, 7th Floor, Philadelphia, PA, 19140, USA.
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4
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Bag-1L Protects against Cell Apoptosis in an In Vitro Model of Lung Ischemia-Reperfusion Injury through the C-Terminal "Bag" Domain. BIOMED RESEARCH INTERNATIONAL 2021; 2021:8822807. [PMID: 34056003 PMCID: PMC8123090 DOI: 10.1155/2021/8822807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 01/13/2021] [Accepted: 02/08/2021] [Indexed: 11/17/2022]
Abstract
Bcl-2-associated athanogene 1 (Bag-1) is a multifunctional and antiapoptotic protein that binds to the antiapoptosis regulator Bcl-2 and promotes cell survival. To investigate the protective function of Bag-1, we examined the effects of Bag-1L, one isoform of Bag-1, in an in vitro cell culture model of lung ischemia-reperfusion injury (LIRI) generated by treatment of A549 cells with hypoxia/reoxygenation. Overexpression of full-length Bag-1L increased the viability of A549 cells and reduced cell apoptosis in response to 6 h of hypoxia/reoxygenation treatment. Furthermore, Bag-1L overexpression enhanced the heat shock protein 70 (HSP70) and Bcl-2 protein levels, increased the phosphorylation of AKT, decreased Bax and cleaved caspase-3 levels, and was able to overcome cell cycle arrest. These effects were not observed in A549 cells overexpressing a truncated form of Bag-1L lacking the "Bag domain," denoted Bag-1L△C. The "Bag domain" is the C-terminal 47 amino acids. Taken together, the results of this study suggest that Bag-1L overexpression can protect against oxidative stress and apoptosis in an in vitro LIRI model, with a dependence on the Bag domain.
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Wang J, Xiang H, Lu Y, Wu T. Role and clinical significance of TGF‑β1 and TGF‑βR1 in malignant tumors (Review). Int J Mol Med 2021; 47:55. [PMID: 33604683 PMCID: PMC7895515 DOI: 10.3892/ijmm.2021.4888] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 01/27/2021] [Indexed: 12/24/2022] Open
Abstract
The appearance and growth of malignant tumors is a complicated process that is regulated by a number of genes. In recent years, studies have revealed that the transforming growth factor-β (TGF-β) signaling pathway serves an important role in cell cycle regulation, growth and development, differentiation, extracellular matrix synthesis and immune response. Notably, two members of the TGF-β signaling pathway, TGF-β1 and TGF-β receptor 1 (TGF-βR1), are highly expressed in a variety of tumors, such as breast cancer, colon cancer, gastric cancer and hepatocellular carcinoma. Moreover, an increasing number of studies have demonstrated that TGF-β1 and TGF-βR1 promote proliferation, migration and epithelial-mesenchymal transition of tumor cells by activating other signaling pathways, signaling molecules or microRNAs (miRs), such as the NF-κB signaling pathway and miR-133b. In addition, some inhibitors targeting TGF-β1 and TGF-βR1 have exhibited positive effects in in vitro experiments. The present review discusses the association between TGF-β1 or TGF-βR1 and tumors, and the development of some inhibitors, hoping to provide more approaches to help identify novel tumor markers to restrain and cure tumors.
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Affiliation(s)
- Junmin Wang
- Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Hongjiao Xiang
- Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Yifei Lu
- Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
| | - Tao Wu
- Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, P.R. China
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6
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Jodoin R, Carrier JC, Rivard N, Bisaillon M, Perreault JP. G-quadruplex located in the 5'UTR of the BAG-1 mRNA affects both its cap-dependent and cap-independent translation through global secondary structure maintenance. Nucleic Acids Res 2019; 47:10247-10266. [PMID: 31504805 PMCID: PMC6821271 DOI: 10.1093/nar/gkz777] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 08/27/2019] [Accepted: 08/31/2019] [Indexed: 12/19/2022] Open
Abstract
The anti-apoptotic BAG-1 protein isoforms are known to be overexpressed in colorectal tumors and are considered to be potential therapeutic targets. The isoforms are derived from alternative translation initiations occuring at four in-frame start codons of a single mRNA transcript. Its 5′UTR also contains an internal ribosome entry site (IRES) regulating the cap-independent translation of the transcript. An RNA G-quadruplex (rG4) is located at the 5′end of the BAG-1 5′UTR, upstream of the known cis-regulatory elements. Herein, we observed that the expression of BAG-1 isoforms is post-transcriptionally regulated in colorectal cancer cells and tumors, and that stabilisation of the rG4 by small molecules ligands reduces the expression of endogenous BAG-1 isoforms. We demonstrated a critical role for the rG4 in the control of both cap-dependent and independent translation of the BAG-1 mRNA in colorectal cancer cells. Additionally, we found an upstream ORF that also represses BAG-1 mRNA translation. The structural probing of the complete 5′UTR showed that the rG4 acts as a steric block which controls the initiation of translation at each start codon of the transcript and also maintains the global 5′UTR secondary structure required for IRES-dependent translation.
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Affiliation(s)
- Rachel Jodoin
- Département de Biochimie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Julie C Carrier
- Service de Gastro-entérologie, Département de médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
| | - Nathalie Rivard
- Département d'Anatomie et de Biologie Cellulaire, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Martin Bisaillon
- Département de Biochimie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
| | - Jean-Pierre Perreault
- Département de Biochimie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec J1E 4K8, Canada
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7
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Song Y, Li Z, Wang Y, Qu Y, Li Q, Man X, Wang F, Hu D. Inhibition of BAG‐1 induced SH‐SY5Y cell apoptosis without affecting Hsp70 expression. J Cell Biochem 2019; 121:1728-1735. [PMID: 31609014 DOI: 10.1002/jcb.29408] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Accepted: 08/28/2019] [Indexed: 01/10/2023]
Affiliation(s)
- Yan‐Kun Song
- Department of Pediatric Emergency The Affiliated Hospital of Qingdao University Qingdao Shandong China
| | - Zhi Li
- Department of Intensive Care Unit Qingdao Municipal Hospital Affiliated to Qingdao University Qingdao Shandong China
| | - Yun Wang
- Department of Pediatric Emergency The Affiliated Hospital of Qingdao University Qingdao Shandong China
| | - Yan Qu
- Department of Intensive Care Unit Qingdao Municipal Hospital Affiliated to Qingdao University Qingdao Shandong China
| | - Qing‐Shu Li
- Department of Intensive Care Unit Qingdao Municipal Hospital Affiliated to Qingdao University Qingdao Shandong China
| | - Xiao‐Yun Man
- Department of Intensive Care Unit Qingdao Municipal Hospital Affiliated to Qingdao University Qingdao Shandong China
| | - Feng‐Tao Wang
- Department of Pediatric Emergency The Affiliated Hospital of Qingdao University Qingdao Shandong China
| | - Dan Hu
- Department of Intensive Care Unit Qingdao Municipal Hospital Affiliated to Qingdao University Qingdao Shandong China
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8
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Zhang H, Li Y, Dickman MB, Wang Z. Cytoprotective Co-chaperone BcBAG1 Is a Component for Fungal Development, Virulence, and Unfolded Protein Response (UPR) of Botrytis cinerea. Front Microbiol 2019; 10:685. [PMID: 31024482 PMCID: PMC6467101 DOI: 10.3389/fmicb.2019.00685] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 03/19/2019] [Indexed: 11/25/2022] Open
Abstract
The Bcl-2 associated athanogene (BAG) family is an evolutionarily conserved group of co-chaperones that confers stress protection against a variety of cellular insults extending from yeasts, plants to humans. Little is known, however, regarding the biological role of BAG proteins in phytopathogenic fungi. Here, we identified the unique BAG gene (BcBAG1) from the necrotrophic fungal pathogen, Botrytis cinerea. BcBAG1 is the homolog of Arabidopsis thaliana AtBAG4, and ectopic expression of BcBAG1 in atbag4 knock-out mutants restores salt tolerance. BcBAG1 deletion mutants (ΔBcbag1) exhibited decreased conidiation, enhanced melanin accumulation and lost the ability to develop sclerotia. Also, BcBAG1 disruption blocked fungal conidial germination and successful penetration, leading to a reduced virulence in host plants. BcBAG1 contains BAG (BD) domain at C-terminus and ubiquitin-like (UBL) domain at N-terminus. Complementation assays indicated that BD can largely restored pathogenicity of ΔBcbag1. Abiotic stress assays showed ΔBcbag1 was more sensitive than the wild-type strain to NaCl, calcofluor white, SDS, tunicamycin, dithiothreitol (DTT), heat and cold stress, suggesting BcBAG1 plays a cytoprotective role during salt stress, cell wall stress, and ER stress. BcBAG1 negatively regulated the expression of BcBIP1, BcIRE1 and the splicing of BcHAC1 mRNA, which are core regulators of unfolded protein response (UPR) during ER stress. Moreover, BcBAG1 interacted with HSP70-type chaperones, BcBIP1 and BcSKS2. In summary, this work demonstrates that BcBAG1 is pleiotropic and not only essential for fungal development, hyphal melanization, and virulence, but also required for response to multiple abiotic stresses and UPR pathway of B. cinerea.
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Affiliation(s)
- Honghong Zhang
- Fujian University Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China.,Institute for Plant Genomics and Biotechnology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States.,Department of Plant Pathology and Microbiology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States
| | - Yurong Li
- Institute for Plant Genomics and Biotechnology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States.,Department of Plant Pathology and Microbiology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States
| | - Martin B Dickman
- Institute for Plant Genomics and Biotechnology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States.,Department of Plant Pathology and Microbiology, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX, United States
| | - Zonghua Wang
- Fujian University Key Laboratory for Plant-Microbe Interaction, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China.,Institute of Oceanography, Minjiang University, Fuzhou, China
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Gennaro VJ, Wedegaertner H, McMahon SB. Interaction between the BAG1S isoform and HSP70 mediates the stability of anti-apoptotic proteins and the survival of osteosarcoma cells expressing oncogenic MYC. BMC Cancer 2019; 19:258. [PMID: 30902071 PMCID: PMC6429775 DOI: 10.1186/s12885-019-5454-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 03/12/2019] [Indexed: 02/07/2023] Open
Abstract
Background The oncoprotein MYC has the dual capacity to drive cell cycle progression or induce apoptosis, depending on the cellular context. BAG1 was previously identified as a transcriptional target of MYC that functions as a critical determinant of this cell fate decision. The BAG1 protein is expressed as multiple isoforms, each having an array of distinct biochemical functions; however, the specific effector function of BAG1 that directs MYC-dependent cell survival has not been defined. Methods In our studies the human osteosarcoma line U2OS expressing a conditional MYC-ER allele was used to induce oncogenic levels of MYC. We interrogated MYC-driven survival processes by modifying BAG1 protein expression. The function of the separate BAG1 isoforms was investigated by depleting cells of endogenous BAG1 and reintroducing the distinct isoforms. Flow cytometry and immunoblot assays were performed to analyze the effect of specific BAG1 isoforms on MYC-dependent apoptosis. These experiments were repeated to determine the role of the HSP70 chaperone complex in BAG1 survival processes. Finally, a proteomic approach was used to identify a set of specific pro-survival proteins controlled by the HSP70/BAG1 complex. Results Loss of BAG1 resulted in robust MYC-induced apoptosis. Expression of the larger isoforms of BAG1, BAG1L and BAG1M, were insufficient to rescue survival in cells with oncogenic levels of MYC. Alternatively, reintroduction of BAG1S significantly reduced the level of apoptosis. Manipulation of the BAG1S interaction with HSP70 revealed that BAG1S provides its pro-survival function by serving as a cofactor for the HSP70 chaperone complex. Via a proteomic approach we identified and classified a set of pro-survival proteins controlled by this HSP70/BAG1 chaperone complex that contribute to the BAG1 anti-apoptotic phenotype. Conclusions The small isoform of BAG1, BAG1S, in cooperation with the HSP70 chaperone complex, selectively mediates cell survival in MYC overexpressing tumor cells. We identified a set of specific pro-survival clients controlled by the HSP70/BAG1S chaperone complex. These clients define new nodes that could be therapeutically targeted to disrupt the survival of tumor cells driven by MYC activation. With MYC overexpression occurring in most human cancers, this introduces new strategies for cancer treatment. Electronic supplementary material The online version of this article (10.1186/s12885-019-5454-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Victoria J Gennaro
- Department of Biochemistry and Molecular Biology Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Helen Wedegaertner
- Department of Biochemistry and Molecular Biology Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Steven B McMahon
- Department of Biochemistry and Molecular Biology Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
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10
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NF-κB pathways in the development and progression of colorectal cancer. Transl Res 2018; 197:43-56. [PMID: 29550444 DOI: 10.1016/j.trsl.2018.02.002] [Citation(s) in RCA: 143] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 02/13/2018] [Accepted: 02/14/2018] [Indexed: 12/12/2022]
Abstract
Nuclear factor-κB (NF-κB) has been widely implicated in the development and progression of cancer. In colorectal cancer (CRC), NF-κB has a key role in cancer-related processes such as cell proliferation, apoptosis, angiogenesis, and metastasis. The role of NF-κB in CRC is complex, owed to the cross talk with other signaling pathways. Although there is sufficient evidence gained from cell lines and animal models that NF-κB is involved in cancer-related processes, because of a lack of studies in human tissue, the clinical evidence of its importance is limited in patients with CRC. This review summarizes evidence relating to how NF-κB is involved in the development and progression of CRC and comments on future work to be carried out.
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11
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Sun J, Pan LM, Chen LB, Wang Y. LncRNA XIST promotes human lung adenocarcinoma cells to cisplatin resistance via let-7i/BAG-1 axis. Cell Cycle 2017; 16:2100-2107. [PMID: 28961027 DOI: 10.1080/15384101.2017.1361071] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Long noncoding RNAs (lncRNAs) have been identified as oncogenes or tumor suppressors that are involved in tumorigenesis and chemoresistance. LncRNA XIST expression is upregulated in several cancers, however, its biologic role in the development of the chemotherapy of human lung adenocarcinoma (LAD) has not been elucidated. This study aimed to observe the expression of LncRNA XIST in LAD and to evaluate its biologic role and clinical significance in the resistance of LAD cells to cisplatin. LncRNA XIST expression was markedly increased in cisplatin-resistant A549/DDP cells compared with parental A549 cells as shown by qRT-PCR. LncRNA XIST overexpression in A549 cells increased their chemosensitivity to cisplatin both in vitro and in vivo by protecting cells from apoptosis and promoting cell proliferation. By contrast, LncRNA XIST knockdown in A549/DDP cells decreased the chemoresistance. We revealed that XIST functioned as competing endogenous RNA to repress let-7i, which controlled its down-stream target BAG-1. We proposed that XIST was responsible for cisplatin resistance of LAD cells and XIST exerted its function through the let-7i/BAG-1 axis. Our findings suggested that lncRNA XIST may be a new marker of poor response to cisplatin and could be a potential therapeutic target for LAD chemotherapy.
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Affiliation(s)
- Jing Sun
- a Health Examination Center , China-Japan Union Hospital of Jilin University , Changchun , China
| | - Li-Ming Pan
- b The First Hospital of Jilin University , Changchun , China
| | - Li-Bo Chen
- c Department of Ultrasound , China-Japan Union Hospital of Jilin University , Changchun , China
| | - Yue Wang
- d Department of Thoracic Surgery , China-Japan Union Hospital of Jilin University , Changchun , China
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12
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Cato L, Neeb A, Sharp A, Buzón V, Ficarro SB, Yang L, Muhle-Goll C, Kuznik NC, Riisnaes R, Nava Rodrigues D, Armant O, Gourain V, Adelmant G, Ntim EA, Westerling T, Dolling D, Rescigno P, Figueiredo I, Fauser F, Wu J, Rottenberg JT, Shatkina L, Ester C, Luy B, Puchta H, Troppmair J, Jung N, Bräse S, Strähle U, Marto JA, Nienhaus GU, Al-Lazikani B, Salvatella X, de Bono JS, Cato ACB, Brown M. Development of Bag-1L as a therapeutic target in androgen receptor-dependent prostate cancer. eLife 2017; 6:e27159. [PMID: 28826504 PMCID: PMC5629025 DOI: 10.7554/elife.27159] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 08/07/2017] [Indexed: 12/12/2022] Open
Abstract
Targeting the activation function-1 (AF-1) domain located in the N-terminus of the androgen receptor (AR) is an attractive therapeutic alternative to the current approaches to inhibit AR action in prostate cancer (PCa). Here we show that the AR AF-1 is bound by the cochaperone Bag-1L. Mutations in the AR interaction domain or loss of Bag-1L abrogate AR signaling and reduce PCa growth. Clinically, Bag-1L protein levels increase with progression to castration-resistant PCa (CRPC) and high levels of Bag-1L in primary PCa associate with a reduced clinical benefit from abiraterone when these tumors progress. Intriguingly, residues in Bag-1L important for its interaction with the AR AF-1 are within a potentially druggable pocket, implicating Bag-1L as a potential therapeutic target in PCa.
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13
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Deregulated MicroRNAs in Biliary Tract Cancer: Functional Targets and Potential Biomarkers. BIOMED RESEARCH INTERNATIONAL 2016; 2016:4805270. [PMID: 27957497 PMCID: PMC5120202 DOI: 10.1155/2016/4805270] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 10/10/2016] [Indexed: 02/07/2023]
Abstract
Biliary tract cancer (BTC) is still a fatal disease with very poor prognosis. The lack of reliable biomarkers for early diagnosis and of effective therapeutic targets is a major demanding problem in diagnosis and management of BTC. Due to the clinically silent and asymptomatic characteristics of the tumor, most patients are diagnosed at an already advanced stage allowing only for a palliative therapeutic approach. MicroRNAs are small noncoding RNAs well known to regulate various cellular functions and pathologic events including the formation and progression of cancer. Over the last years, several studies have shed light on the role of microRNAs in BTC, making them potentially attractive therapeutic targets and candidates as biomarkers. In this review, we will focus on the role of oncogenic and tumor suppressor microRNAs and their direct targets in BTC. Furthermore, we summarize and discuss data that evaluate the diagnostic power of deregulated microRNAs as possible future biomarkers for BTC.
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Greenhough J, Papadakis ES, Cutress RI, Townsend PA, Oreffo ROC, Tare RS. Regulation of osteoblast development by Bcl-2-associated athanogene-1 (BAG-1). Sci Rep 2016; 6:33504. [PMID: 27633857 PMCID: PMC5025845 DOI: 10.1038/srep33504] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 08/25/2016] [Indexed: 12/25/2022] Open
Abstract
BCL-2-associated athanogene-1 (BAG-1) is expressed by osteoblast-lineage cells; early embryonic lethality in Bag-1 null mice, however, has limited the investigation of BAG-1 function in osteoblast development. In the present study, bone morphogenetic protein-2/BMP-2-directed osteogenic differentiation of bone marrow stromal cells (BMSCs) of Bag-1+/− (heterozygous) female mice was decreased significantly. Genes crucial for osteogenic differentiation, bone matrix formation and mineralisation were expressed at significantly lower levels in cultures of Bag-1+/− BMSCs supplemented with BMP-2, while genes with roles in inhibition of BMP-2-directed osteoblastogenesis were significantly upregulated. 17-β-estradiol (E2) enhanced responsiveness of BMSCs of wild-type and Bag-1+/− mice to BMP-2, and promoted robust BMP-2-stimulated osteogenic differentiation of BMSCs. BAG-1 can modulate cellular responses to E2 by regulating the establishment of functional estrogen receptors (ERs), crucially, via its interaction with heat shock proteins (HSC70/HSP70). Inhibition of BAG-1 binding to HSC70 by the small-molecule chemical inhibitor, Thioflavin-S, and a short peptide derived from the C-terminal BAG domain, which mediates binding with the ATPase domain of HSC70, resulted in significant downregulation of E2/ER-facilitated BMP-2-directed osteogenic differentiation of BMSCs. These studies demonstrate for the first time the significance of BAG-1-mediated protein-protein interactions, specifically, BAG-1-regulated activation of ER by HSC70, in modulation of E2-facilitated BMP-2-directed osteoblast development.
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Affiliation(s)
- Joanna Greenhough
- Centre for Human Development, Stem Cells and Regeneration, Institute of Developmental Sciences, University of Southampton, Southampton SO16 6YD, United Kingdom
| | - Emmanouil S Papadakis
- Cancer Research UK Centre Cancer Sciences Unit, Somers Building, University of Southampton, Southampton SO16 6YD, United Kingdom
| | - Ramsey I Cutress
- Cancer Research UK Centre Cancer Sciences Unit, Somers Building, University of Southampton, Southampton SO16 6YD, United Kingdom
| | - Paul A Townsend
- Institute of Cancer Sciences, Manchester Cancer Research Centre, University of Manchester, Manchester M13 9WL, United Kingdom
| | - Richard O C Oreffo
- Centre for Human Development, Stem Cells and Regeneration, Institute of Developmental Sciences, University of Southampton, Southampton SO16 6YD, United Kingdom
| | - Rahul S Tare
- Centre for Human Development, Stem Cells and Regeneration, Institute of Developmental Sciences, University of Southampton, Southampton SO16 6YD, United Kingdom
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Papadakis ES, Barker CR, Syed H, Reeves T, Schwaiger S, Stuppner H, Troppmair J, Blaydes JP, Cutress RI. The Bag-1 inhibitor, Thio-2, reverses an atypical 3D morphology driven by Bag-1L overexpression in a MCF-10A model of ductal carcinoma in situ. Oncogenesis 2016; 5:e215. [PMID: 27043661 PMCID: PMC4848832 DOI: 10.1038/oncsis.2016.10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 12/04/2015] [Accepted: 12/16/2015] [Indexed: 12/21/2022] Open
Abstract
Mammary MCF-10A cells seeded on reconstituted basement membrane form spherical structures with a hollow central lumen, termed acini, which are a physiologically relevant model of mammary morphogenesis. Bcl-2-associated athanogene 1 (Bag-1) is a multifunctional protein overexpressed in breast cancer and ductal carcinoma in situ. When present in the nucleus Bag-1 is predictive of clinical outcome in breast cancer. Bag-1 exists as three main isoforms, which are produced by alternative translation initiation from a single mRNA. The long isoform of Bag-1, Bag-1L, contains a nuclear localisation sequence not present in the other isoforms. When present in the nucleus Bag-1L, but not the other Bag-1 isoforms, can interact with and modulate the activities of estrogen-, androgen- and vitamin D-receptors. Overexpression of Bag-1 mRNA in MCF-10A is known to produce acini with luminal filling reminiscent of ductal carcinoma in situ. As this mRNA predominantly overexpresses the short isoform of Bag-1, Bag-1S, we set out to examine whether the nuclear Bag-1L isoform is sufficient to drive premalignant change by developing a Bag-1L-overexpressing MCF-10A model. Two clones differentially overexpressing Bag-1L were grown in two-dimensional (2D) and three-dimensional (3D) cultures and compared with an established model of HER2-driven transformation. In 2D cultures, Bag-1L overexpression reduced proliferation but did not affect growth factor responsiveness or clonogenicity. Acini formed by Bag-1L-overexpressing cells exhibited reduced luminal clearing when compared with controls. An abnormal branching morphology was also observed which correlated with the level of Bag-1L overexpression, suggesting further malignant change. Treatment with Thio-2, a small-molecule inhibitor of Bag-1, reduced the level of branching. In summary, 3D cultures of MCF-10A mammary epithelial cells overexpressing Bag-1L demonstrate a premalignant phenotype with features of ductal carcinoma in situ. Using this model to test the small-molecule Bag-1 inhibitor, Thio-2, reveals its potential to reverse the atypical branched morphology of acini that characterizes this premalignant change.
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Affiliation(s)
- E S Papadakis
- Cancer Research UK Centre Cancer Sciences Unit, University of Southampton Faculty of Medicine, Southampton General Hospital, Southampton, UK
| | - C R Barker
- Cancer Research UK Centre Cancer Sciences Unit, University of Southampton Faculty of Medicine, Southampton General Hospital, Southampton, UK
| | - H Syed
- Cancer Research UK Centre Cancer Sciences Unit, University of Southampton Faculty of Medicine, Southampton General Hospital, Southampton, UK
| | - T Reeves
- Cancer Research UK Centre Cancer Sciences Unit, University of Southampton Faculty of Medicine, Southampton General Hospital, Southampton, UK
| | - S Schwaiger
- Institute of Pharmacy/Pharmacognosy, Center of Molecular Biosciences, University of Innsbruck, Innrain, Innsbruck, Austria
| | - H Stuppner
- Institute of Pharmacy/Pharmacognosy, Center of Molecular Biosciences, University of Innsbruck, Innrain, Innsbruck, Austria
| | - J Troppmair
- Daniel Swarovski Research Laboratory, Department of Visceral-, Transplant- and Thoracic Surgery, Innsbruck Medical University, Austria
| | - J P Blaydes
- Cancer Research UK Centre Cancer Sciences Unit, University of Southampton Faculty of Medicine, Southampton General Hospital, Southampton, UK
| | - R I Cutress
- Cancer Research UK Centre Cancer Sciences Unit, University of Southampton Faculty of Medicine, Southampton General Hospital, Southampton, UK.,University Hospital Southampton, University of Southampton Faculty of Medicine, Southampton General Hospital, Southampton, UK
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Wang Y, Ha M, Liu J, Li P, Zhang W, Zhang X. Role of BCL2-associated athanogene in resistance to platinum-based chemotherapy in non-small-cell lung cancer. Oncol Lett 2015; 11:984-990. [PMID: 26893680 PMCID: PMC4734146 DOI: 10.3892/ol.2015.4003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 07/07/2015] [Indexed: 01/29/2023] Open
Abstract
The present study aimed to address the pharmacogenetic role of BAG1 in platinum-based chemotherapy in advanced non-small-cell lung cancer (NSCLC) and in cultured human lung adenocarcinoma A549 cells. A total of 108 NSCLC patients (stages I-IIIA) were treated with a standard chemotherapy regimen of cisplatin plus vinorelbine. Additionally, in vitro cultured A549 cells were treated with cisplatin in the presence or absence of tunicamycin. Cell proliferation was determined by MTT assay and protein levels were assessed via western blot analysis. Patients with BAG1-positive expression were revealed to have a prolonged survival time (progression-free survival, 24.0 months) compared with that of patients without BAG1 expression (21.6 months; χ2=18.018, P<0.05). Treatment of A549 cells with tunicamycin followed by cisplatin resulted in elevated BAG1 levels. In addition, tunicamycin was found to significantly enhance cisplatin-induced growth inhibition and apoptosis in A549 cells. The results indicate that BAG1 is important in cisplatin-induced cell death in lung adenocarcinoma, suggesting that endoplasmic reticulum stress may promote the sensitivity of NSCLC patients to chemotherapy.
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Affiliation(s)
- Yadi Wang
- Department of Oncology, Third Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121000, P.R. China
| | - Minwen Ha
- Department of Oncology, First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121000, P.R. China
| | - Jingsong Liu
- Department of Heart Surgery, First Affiliated Hospital of Xuzhou Medical College, Jinzhou, Liaoning 121000, P.R. China
| | - Ping Li
- Department of Oncology, First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121000, P.R. China
| | - Wenlu Zhang
- Department of Oncology, First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121000, P.R. China
| | - Xuan Zhang
- Department of Oncology, First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121000, P.R. China
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Ma F, Zhang M, Gong W, Weng M, Quan Z. MiR-138 Suppresses Cell Proliferation by Targeting Bag-1 in Gallbladder Carcinoma. PLoS One 2015; 10:e0126499. [PMID: 25962180 PMCID: PMC4427488 DOI: 10.1371/journal.pone.0126499] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 04/02/2015] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND MiR-138 is frequently downregulated in different cancer types and is thought to be involved in the progression of tumorigenesis. However, the molecular mechanism of miR-138 involvement in gallbladder carcinoma still remains unknown. METHODS The expression of miR-138 in 49 gallbladder carcinoma samples and paired normal gallbladder samples was analyzed using quantitative reverse transcription-polymerase chain reaction. The biological functions of miR-138 and Bag-1 (Bcl-2-associated athanogene-1) on cell proliferation were examined using 3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide and apoptosis assays. Targets of miR-138 were predicted using bioinformatics and validated using luciferase reporter and Western blot analyses. The in vivo effects of miR-138 were examined using subcutaneous inoculation of gallbladder carcinoma cells in Balb/c nude mice. RESULTS Compared with their paired normal gallbladder samples, the gallbladder carcinoma samples had decreased expression of miR-138 and increased expression of Bag-1. Overexpression of miR-138 inhibited the proliferation of gallbladder carcinoma cells. Bag-1 was defined as a novel target of miR-138. Both the inhibition of Bag-1 by miR-138 and the silencing of Bag-1 by siRNA led to alterations of apoptosis-related proteins such as Bcl-2 and Bax. Restoring expression of Bag-1 eliminates the effects of miR-138 on cell proliferation and apoptosis. Furthermore, overexpression of miR-138 markedly inhibited the growth of tumors in the gallbladder carcinoma xenograft model in nude mice. CONCLUSIONS Expression of miR-138 is frequently reduced in gallbladder carcinoma when compared to normal cells. Overexpression of miR-138 inhibited cell proliferation by directly suppressing the expression of Bag-1. These results suggest that miR-138 plays an important role in inhibiting the growth of gallbladder carcinoma.
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Affiliation(s)
- Fei Ma
- Department of Oncology, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Mingdi Zhang
- Department of Surgery, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Wei Gong
- Department of Surgery, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Mingzhe Weng
- Department of Surgery, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Zhiwei Quan
- Department of Surgery, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
- * E-mail:
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Guo K, Li L, Yin G, Zi X, Liu L. Bag5 protects neuronal cells from amyloid β-induced cell death. J Mol Neurosci 2014; 55:815-20. [PMID: 25367796 DOI: 10.1007/s12031-014-0433-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 09/29/2014] [Indexed: 12/23/2022]
Abstract
The pathological mechanism of Alzheimer's disease (AD) needs to be elucidated. The Bcl-2 associated athanogene 5 (Bag5) is an important member in the Bag family. However, the role of Bag5 in AD has not yet been elucidated. In this study, we found that expression of Bag5 is elevated in the brains of AD transgenic Tg2576 mice at both mRNA levels and proteins. In vitro experiments indicated that Aβ1-42 treatment led to the upregulation of Bag5 in a dose-dependent manner. In addition, our results indicated that inhibition of Bag5 using small RNA interferences exacerbated Aβ1-42-induced neurotoxicity. On one hand, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assay demonstrated that inhibition of Bag5 exacerbated Aβ1-42-related cell death. On the other hand, silence of endogenous Bag5 promotes the generation of reactive oxygen species (ROS) and malondialdehyde (MDA) induced by Aβ1-42. Finally and importantly, it was shown that knockdown of Bag5 exacerbated Aβ1-42-induced apoptosis and caspase-3 cleavage. These data suggest that induction of Bag5 might have a neuroprotective effect in AD.
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Affiliation(s)
- Ke Guo
- Department of Neurology, the Third Xiangya Hospital of Central South University, 138 Tongzipo Rd, 410013, Changsha, China
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Bruchmann A, Roller C, Walther TV, Schäfer G, Lehmusvaara S, Visakorpi T, Klocker H, Cato ACB, Maddalo D. Bcl-2 associated athanogene 5 (Bag5) is overexpressed in prostate cancer and inhibits ER-stress induced apoptosis. BMC Cancer 2013; 13:96. [PMID: 23448667 PMCID: PMC3598994 DOI: 10.1186/1471-2407-13-96] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 02/18/2013] [Indexed: 02/03/2023] Open
Abstract
Background The Bag (Bcl-2 associated athanogene) family of proteins consists of 6 members sharing a common, single-copied Bag domain through which they interact with the molecular chaperone Hsp70. Bag5 represents an exception in the Bag family since it consists of 5 Bag domains covering the whole protein. Bag proteins like Bag1 and Bag3 have been implicated in tumor growth and survival but it is not known whether Bag5 also exhibits this function. Methods Bag5 mRNA and protein expression levels were investigated in prostate cancer patient samples using real-time PCR and immunoblot analyses. In addition immunohistological studies were carried out to determine the expression of Bag5 in tissue arrays. Analysis of Bag5 gene expression was carried out using one-way ANOVA and Bonferroni’s Multiple Comparison test. The mean values of the Bag5 stained cells in the tissue array was analyzed by Mann-Whitney test. Functional studies of the role of Bag5 in prostate cancer cell lines was performed using overexpression and RNA interference analyses. Results Our results show that Bag5 is overexpressed in malignant prostate tissue compared to benign samples. In addition we could show that Bag5 levels are increased following endoplasmic reticulum (ER)-stress induction, and Bag5 relocates from the cytoplasm to the ER during this process. We also demonstrate that Bag5 interacts with the ER-resident chaperone GRP78/BiP and enhances its ATPase activity. Bag5 overexpression in 22Rv.1 prostate cancer cells inhibited ER-stress induced apoptosis in the unfolded protein response by suppressing PERK-eIF2-ATF4 activity while enhancing the IRE1-Xbp1 axis of this pathway. Cells expressing high levels of Bag5 showed reduced sensitivity to apoptosis induced by different agents while Bag5 downregulation resulted in increased stress-induced cell death. Conclusions We have therefore shown that Bag5 is overexpressed in prostate cancer and plays a role in ER-stress induced apoptosis. Furthermore we have identified GRP78/BiP as a novel interaction partner of Bag5.
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Affiliation(s)
- Anja Bruchmann
- Karlsruhe Institute of Technology, Institute of Toxicology and Genetics, Hermann-von-Helmholtz Platz 1, Eggenstein-Leopoldshafen 76344, Germany
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Assimon VA, Gillies AT, Rauch JN, Gestwicki JE. Hsp70 protein complexes as drug targets. Curr Pharm Des 2013; 19:404-17. [PMID: 22920901 PMCID: PMC3593251 DOI: 10.2174/138161213804143699] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 08/15/2012] [Indexed: 12/22/2022]
Abstract
Heat shock protein 70 (Hsp70) plays critical roles in proteostasis and is an emerging target for multiple diseases. However, competitive inhibition of the enzymatic activity of Hsp70 has proven challenging and, in some cases, may not be the most productive way to redirect Hsp70 function. Another approach is to inhibit Hsp70's interactions with important co-chaperones, such as J proteins, nucleotide exchange factors (NEFs) and tetratricopeptide repeat (TPR) domain-containing proteins. These co-chaperones normally bind Hsp70 and guide its many diverse cellular activities. Complexes between Hsp70 and co-chaperones have been shown to have specific functions, including roles in pro-folding, pro-degradation and pro-trafficking pathways. Thus, a promising strategy may be to block protein- protein interactions between Hsp70 and its co-chaperones or to target allosteric sites that disrupt these contacts. Such an approach might shift the balance of Hsp70 complexes and re-shape the proteome and it has the potential to restore healthy proteostasis. In this review, we discuss specific challenges and opportunities related to these goals. By pursuing Hsp70 complexes as drug targets, we might not only develop new leads for therapeutic development, but also discover new chemical probes for use in understanding Hsp70 biology.
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Affiliation(s)
- Victoria A Assimon
- Department of Pathology, Life Sciences Institute, University of Michigan, 210 Washtenaw Ave., Ann Arbor, MI 48109-2216, USA
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21
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Aveic S, Pigazzi M, Basso G. BAG1: the guardian of anti-apoptotic proteins in acute myeloid leukemia. PLoS One 2011; 6:e26097. [PMID: 22016818 PMCID: PMC3189928 DOI: 10.1371/journal.pone.0026097] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 09/19/2011] [Indexed: 02/01/2023] Open
Abstract
BCL2 associated Athano-Gene 1 (BAG1) is a multifunctional protein that has been described to be involved in different cell processes linked to cell survival. It has been reported as deregulated in diverse cancer types. Here, BAG1 protein was found highly expressed in children with acute myeloid leukemia at diagnosis, and in a cohort of leukemic cell lines. A silencing approach was used for determining BAG1's role in AML, finding that its down-regulation decreased expression of BCL2, BCL-XL, MCL1, and phospho-ERK1/2, all proteins able to sustain leukemia, without affecting the pro-apoptotic protein BAX. BAG1 down-regulation was also found to increase expression of BAG3, whose similar activity was able to compensate the loss of function of BAG1. BAG1/BAG3 co-silencing caused an enhanced cell predisposition to death in cell lines and also in primary AML cultures, affecting the same proteins. Cell death was CASPASE-3 dependent, was accompanied by PARP cleavage and documented by an increased release of pro-apoptotic molecules Smac/DIABLO and Cytochrome c. BAG1 was found to directly maintain BCL2 and to protect MCL1 from proteasomal degradation by controlling USP9X expression, which appeared to be its novel target. Finally, BAG1 was found able to affect leukemia cell fate by influencing the expression of anti-apoptotic proteins crucial for AML maintenance.
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MESH Headings
- Adaptor Proteins, Signal Transducing/deficiency
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Apoptosis Regulatory Proteins/metabolism
- Cell Survival/genetics
- Child
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Gene Expression Regulation, Neoplastic
- Gene Silencing
- HL-60 Cells
- Humans
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/metabolism
- Leukemia, Myeloid, Acute/pathology
- Proteasome Endopeptidase Complex/metabolism
- Proteolysis
- Transcription Factors/deficiency
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Ubiquitin Thiolesterase/metabolism
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Affiliation(s)
- Sanja Aveic
- Hematology-Oncology Laboratory, Pediatrics Department, University of Padova, Padova, Italy
| | - Martina Pigazzi
- Hematology-Oncology Laboratory, Pediatrics Department, University of Padova, Padova, Italy
| | - Giuseppe Basso
- Hematology-Oncology Laboratory, Pediatrics Department, University of Padova, Padova, Italy
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Co-overexpression of Bag-1 and heat shock protein 70 in human epidermal squamous cell carcinoma: Bag-1-mediated resistance to 5-fluorouracil-induced apoptosis. Br J Cancer 2011; 104:1459-71. [PMID: 21522149 PMCID: PMC3101929 DOI: 10.1038/bjc.2011.111] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Background: The aim was to determine whether Bcl-2-associated athanogene-1 (Bag-1) and/or its binding protein heat shock protein-70 (Hsp70) exhibit deregulated expression in epidermal squamous cell carcinoma (SCC) and whether Bag-1 confers apoptosis resistance. Method: Immunohistochemistry for Bag-1 and Hsp70 was performed on 60 epidermal SCC and 10 normal skin samples. The epidermal SCC cell line SCC-13 was treated with 5-fluorouracil (5-FU) after Bag-1 knockdown to determine whether high Bag-1 levels contribute to growth and/or apoptosis resistance. Results: Normal epithelium expressed primarily nuclear Bag-1. Most tumours showed reduced nuclear Bag-1 staining, but a subset exhibited strong Bag-1 staining, with cytoplasmic Bag-1 staining intensity correlating with cytoplasmic Hsp70 staining intensity (rs=0.462; P<0.001) and less differentiation (P<0.001). Bag-1 knockdown resulted in markedly reduced SCC-13 cell yield, increased spontaneous apoptosis and enhanced sensitivity to 5-FU-induced apoptosis. Apoptosis induced by 5-FU in the Bag-1-knockdown cells was significantly greater than the additive apoptotic effect of 5-FU or Bag-1 knockdown alone. Conclusions: Overexpression of Bag-1 and Hsp70 in poorly differentiated SCC may confer both enhanced tumour cell growth and apoptosis resistance. Bag-1 may contribute to the resistance of more advanced epidermal SCC to chemotherapy.
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Ozaki T, Kubo N, Nakagawara A. p73-Binding Partners and Their Functional Significance. INTERNATIONAL JOURNAL OF PROTEOMICS 2011; 2010:283863. [PMID: 22084676 PMCID: PMC3195385 DOI: 10.1155/2010/283863] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 10/26/2010] [Indexed: 12/21/2022]
Abstract
p73 is one of the tumor-suppressor p53 family of nuclear transcription factor. As expected from the structural similarity between p53 and p73, p73 has a tumor-suppressive function. However, p73 was rarely mutated in human primary tumors. Under normal physiological conditions, p73 is kept at an extremely low level to allow cells normal growth. In response to a certain subset of DNA damages, p73 is induced dramatically and transactivates an overlapping set of p53-target genes implicated in the promotion of cell cycle arrest and/or apoptotic cell death. Cells undergo cell cycle arrest and/or apoptotic cell death depending on the type and strength of DNA damages. p73 is regulated largely through the posttranslational modifications such as phosphorylation and acetylation. These chemical modifications are tightly linked to direct protein-protein interactions. In the present paper, the authors describe the functional significance of the protein-protein interactions in the regulation of proapoptotic p73.
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Affiliation(s)
- Toshinori Ozaki
- Laboratory of Anti-tumor Research, Chiba Cancer Center Research Institute, Chiba 260-8717, Japan
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Bag1-L is a phosphorylation-dependent coactivator of c-Jun during neuronal apoptosis. Mol Cell Biol 2010; 30:3842-52. [PMID: 20516211 DOI: 10.1128/mcb.01610-09] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
In the nervous system, cell death by apoptosis plays a critical role during normal development and pathological neurodegeneration. Jun N-terminal kinases (JNKs) are essential regulators of neuronal apoptosis. The AP-1 transcription factor c-Jun is phosphorylated at multiple sites within its transactivation domain by the JNKs, and c-Jun phosphorylation is required for JNK-induced neurotoxicity. While the importance of c-Jun as a mediator of apoptotic JNK signaling in neurons is firmly established, the molecular mechanism underlying the requirement for c-Jun N-terminal phosphorylation is enigmatic. Here we identify the multifunctional protein Bag1-L as a coactivator of phosphorylated c-Jun. Bag1-L preferentially interacts with N-terminally phosphorylated c-Jun, and Bag1-L greatly augments transcriptional activation by phosphorylated c-Jun. Chromatin immunoprecipitation experiments revealed binding of Bag1-L to the promoters of proapoptotic AP-1 target genes, and overexpression of Bag1-L augmented cell death in primary neurons. Therefore, Bag1-L functions as a coactivator regulating neurotoxicity mediated by phosphorylated c-Jun.
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Deeg S, Gralle M, Sroka K, Bähr M, Wouters FS, Kermer P. BAG1 restores formation of functional DJ-1 L166P dimers and DJ-1 chaperone activity. ACTA ACUST UNITED AC 2010; 188:505-13. [PMID: 20156966 PMCID: PMC2828921 DOI: 10.1083/jcb.200904103] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The L166P mutation in DJ-1 is associated with Parkinson’s disease. DJ-1–interacting protein BAG1 chaperones mutant DJ-1 and reverses its mutant phenotype. Mutations in the gene coding for DJ-1 protein lead to early-onset recessive forms of Parkinson’s disease. It is believed that loss of DJ-1 function is causative for disease, although the function of DJ-1 still remains a matter of controversy. We show that DJ-1 is localized in the cytosol and is associated with membranes and organelles in the form of homodimers. The disease-related mutation L166P shifts its subcellular distribution to the nucleus and decreases its ability to dimerize, impairing cell survival. Using an intracellular foldase biosensor, we found that wild-type DJ-1 possesses chaperone activity, which is abolished by the L166P mutation. We observed that this aberrant phenotype can be reversed by the expression of the cochaperone BAG1 (Bcl-2–associated athanogene 1), restoring DJ-1 subcellular distribution, dimer formation, and chaperone activity and ameliorating cell survival.
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Affiliation(s)
- Sebastian Deeg
- Department for Neurology, Georg-August University Göttingen, 37073 Göttingen, Germany
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Sharp A, Crabb SJ, Johnson PWM, Hague A, Cutress R, Townsend PA, Ganesan A, Packham G. Thioflavin S (NSC71948) interferes with Bcl-2-associated athanogene (BAG-1)-mediated protein-protein interactions. J Pharmacol Exp Ther 2009; 331:680-9. [PMID: 19690191 DOI: 10.1124/jpet.109.153601] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The C-terminal BAG domain is thought to play a key role in BAG-1-induced survival and proliferation by mediating protein-protein interactions, for example, with heat shock proteins HSC70 and HSP70, and with RAF-1 kinase. Here, we have identified thioflavin S (NSC71948) as a potential small-molecule chemical inhibitor of these interactions. NSC71948 inhibited the interaction of BAG-1 and HSC70 in vitro and decreased BAG-1:HSC70 and BAG-1:HSP70 binding in intact cells. NSC71948 also reduced binding between BAG-1 and RAF-1, but had no effect on the interaction between two unrelated proteins, BIM and MCL-1. NSC71948 functionally reversed the ability of BAG-1 to promote vitamin D3 receptor-mediated transactivation, an activity of BAG-1 that depends on HSC70/HSP70 binding, and reduced phosphorylation of p44/42 mitogen-activate protein kinase. NSC71948 can be used to stain amyloid fibrils; however, structurally related compounds, thioflavin T and BTA-1, had no effect on BAG-1:HSC70 binding, suggesting that structural features important for amyloid fibril binding and inhibition of BAG-1:HSC70 binding may be separable. We demonstrated that NSC71948 inhibited the growth of BAG-1 expressing human ZR-75-1 breast cancer cells and wild-type, but not BAG-1-deficient, mouse embryo fibroblasts. Taken together, these data suggest that NSC71948 may be a useful molecule to investigate the functional significance of BAG-1 C-terminal protein interactions. However, it is important to recognize that NSC71948 may exert additional "off-target" effects. Inhibition of BAG-1 function may be an attractive strategy to inhibit the growth of BAG-1-overexpressing cancers, and further screens of additional compound collections may be warranted.
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Affiliation(s)
- Adam Sharp
- Cancer Research UK Centre, Cancer Sciences Division, University of Southampton School of Medicine, Southampton General Hospital, Southampton, United Kingdom
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Abstract
High-level expression of Bcl-2 associated athanogene (BAG-1) protects cancer cells from stress-induced cell death and growth inhibition. These protective effects of BAG-1 are dependent on interactions with the HSC70 and HSP70 chaperones. However, the key stress-response molecules that are regulated by a BAG-1/chaperone mechanism have not been identified. In this study, we investigated the effects of BAG-1 overexpression on the function of p53 family proteins, p53, p63 and p73. Overexpression of BAG-1 isoforms interfered with the transactivating activity of p73 and p63, but had modest and variable effects on p53-dependent transcription. p73 and BAG-1 interacted in intact cells and overexpression of BAG-1 decreased the expression of p73. siRNA-mediated ablation of endogenous BAG-1 increased the activity of a p73-responsive promoter and this was reversed by knock-down of p73. The ability of BAG-1 to modulate p73 activity and expression, and to interact with p73 were dependent on amino acid residues required for the interaction of BAG-1 with HSC70 and HSP70. These results show that BAG-1 inhibits the transactivating functions of p73 and provide new insight into the mechanisms that control the expression of p73. Inhibition of p73 function may be one mechanism that contributes to the pro-survival activity of BAG-1.
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Gehring U. Multiple, but concerted cellular activities of the human protein Hap46/BAG-1M and isoforms. Int J Mol Sci 2009; 10:906-928. [PMID: 19399228 PMCID: PMC2672009 DOI: 10.3390/ijms10030906] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Accepted: 02/23/2009] [Indexed: 12/18/2022] Open
Abstract
The closely related human and murine proteins Hap46/BAG-1M and BAG-1, respectively, were discovered more than a decade ago by molecular cloning techniques. These and the larger isoform Hap50/BAG-1L, as well as shorter isoforms, have the ability to interact with a seemingly unlimited array of proteins of completely unrelated structures. This problem was partially resolved when it was realized that molecular chaperones of the hsp70 heat shock protein family are major primary association partners, binding being mediated by the carboxy terminal BAG-domain and the ATP-binding domain of hsp70 chaperones. The latter, in turn, can associate with an almost unlimited variety of proteins through their substrate-binding domains, so that ternary complexes may result. The protein folding activity of hsp70 chaperones is affected by interactions with Hap46/BAG-1M or isoforms. However, there also exist several proteins which bind to Hap46/BAG-1M and isoforms independent of hsp70 mediation. Moreover, Hap46/BAG-1M and Hap50/BAG-1L, but not the shorter isoforms, can bind to DNA in a sequence-independent manner by making use of positively charged regions close to their amino terminal ends. This is the molecular basis for their effects on transcription which are of major physiological relevance, as discussed here in terms of a model. The related proteins Hap50/BAG-1L and Hap46/BAG-1M may thus serve as molecular links between such diverse bioactivities as regulation of gene expression and protein quality control. These activities are coordinated and synergize in helping cells to cope with conditions of external stress. Moreover, they recently became markers for the aggressiveness of several cancer types.
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Affiliation(s)
- Ulrich Gehring
- Biochemie-Zentrum der Universität Heidelberg, INF 328, D-69120 Heidelberg, Germany
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Gurusamy N, Lekli I, Gorbunov NV, Gherghiceanu M, Popescu LM, Das DK. Cardioprotection by adaptation to ischaemia augments autophagy in association with BAG-1 protein. J Cell Mol Med 2009; 13:373-87. [PMID: 18793351 PMCID: PMC3823363 DOI: 10.1111/j.1582-4934.2008.00495.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 09/04/2008] [Indexed: 01/08/2023] Open
Abstract
Autophagy is an intracellular process in which a cell digests its own constituents via lysosomal degradative pathway. Though autophagy has been shown in several cardiac diseases like heart failure, hypertrophy and ischaemic cardiomyopathy, the role and the regulation of autophagy is still largely unknown. Bcl-2-associated athanogene (BAG-1) is a multifunctional pro-survival molecule that binds with Hsp70/Hsc70. In this study, myocardial adaptation to ischaemia by repeated brief episodes of ischaemia and reperfusion (I/R) prior to lethal I/R enhanced the expression of autophagosomal membrane specific protein light chain 3 (LC3)-II, and Beclin-1, a molecule involved in autophagy and BAG-1. Autophagosomes structures were found in the adapted myocardium through electron microscopy. Co-immunoprecipitation and co-immunofluorescence analyses revealed that LC3-II was bound with BAG-1. Inhibition of autophagy by treating rats with Wortmannin (15 microg/kg; intraperitoneally) abolished the ischaemic adaptation-induced induction of LC3-II, Beclin-1, BAG-1 and cardioprotection. Intramyocardial injection of BAG-1 siRNA attenuated the induction of LC3-II, and abolished the cardioprotection achieved by adaptation. Furthermore, hypoxic adaptation in cardiac myoblast cells induced LC3-II and BAG-1. BAG-1 siRNA treatment attenuated hypoxic adaptation-induced LC3-II and BAG-1, and abolished improvement in cardiac cell survival and reduction of cell death. These results clearly indicate that myocardial protection elicited by adaptation is mediated at least in part via up-regulation of autophagy in association with BAG-1 protein.
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Affiliation(s)
- Narasimman Gurusamy
- Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, CT, USA
| | - Istvan Lekli
- Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, CT, USA
| | | | | | - Lawrence M Popescu
- ‘Victor Babes’, National Institute of Pathology, Bucharest, Romania
- Department of Cellular and Molecular Medicine, ‘Carol Davila’ University of Medicine and Pharmacy, Bucharest, Romania
| | - Dipak K Das
- Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, CT, USA
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Dobbyn HC, Hill K, Hamilton TL, Spriggs KA, Pickering BM, Coldwell MJ, de Moor CH, Bushell M, Willis AE. Regulation of BAG-1 IRES-mediated translation following chemotoxic stress. Oncogene 2007; 27:1167-74. [PMID: 17700523 PMCID: PMC2570717 DOI: 10.1038/sj.onc.1210723] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
There are three major isoforms of BAG-1 in mammalian cells, termed BAG-1L (p50), BAG-1M (p46) and BAG-1S (p36) that function as pro-survival proteins and are associated with tumorigenesis and chemoresistance. Initiation of BAG-1 protein synthesis can occur by both cap-dependent and cap-independent mechanisms and it has been shown that synthesis of BAG-1S is dependent upon the presence of an internal ribosome entry segment (IRES) in the 5'-UTR of BAG-1 mRNA. We have shown previously that BAG-1 IRES-meditated initiation of translation requires two trans-acting factors poly (rC) binding protein 1 (PCBP1) and polypyrimidine tract binding protein (PTB) for function. The former protein allows BAG-1 IRES RNA to attain a structure that permits binding of the ribosome, while the latter protein appears to be involved in ribosome recruitment. Here, we show that the BAG-1 IRES maintains synthesis of BAG-1 protein following exposure of cells to the chemotoxic drug vincristine but not to cisplatin and that this is brought about, in part, by the relocalization of PTB and PCBP1 from the nucleus to the cytoplasm.
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Affiliation(s)
- H C Dobbyn
- School of Pharmacy, University of Nottingham, Nottingham, UK
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Peng CW, Zhao B, Chen HC, Chou ML, Lai CY, Lin SZ, Hsu HY, Kieff E. Hsp72 up-regulates Epstein-Barr virus EBNALP coactivation with EBNA2. Blood 2007; 109:5447-54. [PMID: 17341665 PMCID: PMC1890828 DOI: 10.1182/blood-2006-08-040634] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The Epstein-Barr virus (EBV) transcriptional coactivator EBNALP specifically associates and colocalizes with Hsp72 in lymphoblastoid cell lines. We now find that overexpression of Hsp72 more than doubled EBNALP coactivation with EBNA2 of a transfected EBV LMP1 promoter in B lymphoblasts, did not affect EBNA2 or EBNALP protein levels, and strongly up-regulated EBNA2 and EBNALP coactivation of LMP1 protein expression from the endogenous EBV genome in latency I infected Akata cells. The Hsp72 ATP, protein binding, and the C-terminal regulatory domains were required for full activity. An EBNALP deletion mutant, EBNALPd45, which does not associate with Hsp72, coactivated with EBNA2, but was not affected by Hsp72 overexpression, despite Hsp72 up-regulation of wild-type EBNALP coactivation with EBNA2 at all levels of EBNALP expression, indicating the importance of Hsp72 association with EBNALP for Hsp72 up-regulation of coactivation. Of importance, a 90% RNAi knockdown of Hsp72 reduced EBNALP coactivation with EBNA2 of transfected EBV LMP1 and Cp promoters by approximately 50%. Overexpression of the Hsp72 C-terminal interacting and regulatory protein, CHIP, strongly down-regulated EBNALP coactivation, independently of CHIP ubiquitin ligase activity. CHIP effects were Hsp72 dependent, indicating a background downmodulating role for CHIP in Hsp72 augmentation of EBNA2 and EBNALP coactivation. Based on these and other cited data, we favor a model in which Hsp72 chaperones EBNALP shuttling of repressors from EBNA2-enhanced promoters.
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Affiliation(s)
- Chih-Wen Peng
- Department of Life Science and Gene Therapy Division, Tzu-Chi University and Hospital, Hualien, Taiwan
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N/A, 关 景, 吕 丽. N/A. Shijie Huaren Xiaohua Zazhi 2006; 14:3219-3223. [DOI: 10.11569/wcjd.v14.i33.3219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Schröder HC, Breter HJ, Fattorusso E, Ushijima H, Wiens M, Steffen R, Batel R, Müller WEG. Okadaic acid, an apoptogenic toxin for symbiotic/parasitic annelids in the demosponge Suberites domuncula. Appl Environ Microbiol 2006; 72:4907-16. [PMID: 16820487 PMCID: PMC1489365 DOI: 10.1128/aem.00228-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2006] [Accepted: 05/08/2006] [Indexed: 11/20/2022] Open
Abstract
The role of okadaic acid (OA) in the defense system of the marine demosponge Suberites domuncula against symbiotic/parasitic annelids was examined. Bacteria within the mesohyl produced okadaic acid at concentrations between 32 ng/g and 58 ng/g of tissue (wet weight). By immunocytochemical methods and by use of antibodies against OA, we showed that the toxin was intracellularly stored in vesicles. Western blotting experiments demonstrated that OA also existed bound to a protein with a molecular weight of 35,000 which was tentatively identified as a galectin (by application of antigalectin antibodies). Annelids that are found in S. domuncula undergo apoptotic cell death. OA is one candidate inducer molecule of this process, since this toxin accumulated in these symbionts/parasites. Furthermore, we identified the cDNA encoding the multifunctional prosurvival molecule BAG-1 in S. domuncula; it undergoes strong expression in the presence of the annelid. Our data suggest that sponges use toxins (here, OA) produced from bacteria to eliminate metazoan symbionts/parasites by apoptosis.
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Affiliation(s)
- Heinz C Schröder
- Institut für Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Universität, Duesbergweg 6, 55099 Mainz, Germany
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Götz R, Kramer BW, Camarero G, Rapp UR. BAG-1 haplo-insufficiency impairs lung tumorigenesis. BMC Cancer 2004; 4:85. [PMID: 15560850 PMCID: PMC539250 DOI: 10.1186/1471-2407-4-85] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Accepted: 11/24/2004] [Indexed: 11/29/2022] Open
Abstract
Background BAG-1 is a multifunctional co-chaperone of heat shock proteins (Hsc70/Hsp70) that is expressed in most cells. It interacts with Bcl-2 and Raf indicating that it might connect protein folding with other signaling pathways. Evidence that BAG-1 expression is frequently altered in human cancers, in particular in breast cancer, relative to normal cells has been put forward but the notion that overexpression of BAG-1 contributes to poor prognosis in tumorigenesis remains controversial. Methods We have evaluated the effect of BAG-1 heterozygosity in mice in a model of non-small-cell lung tumorigenesis with histological and molecular methods. We have generated mice heterozygous for BAG-1, carrying a BAG-1 null allele, that in addition express oncogenic, constitutively active C-Raf kinase (SP-C C-Raf BxB) in type II pneumocytes. SP-C C-Raf BxB mice develop multifocal adenomas early in adulthood. Results We show that BAG-1 heterozygosity in mice impairs C-Raf oncogene-induced lung adenoma growth. Lung tumor initiation was reduced by half in BAG-1 heterozygous SP-C C-Raf BxB mice compared to their littermates. Tumor area was reduced by 75% in 4 month lungs of BAG-1 haploinsufficient mice compared to mice with two BAG-1 copies. Whereas BAG-1 heterozygosity did not affect the rate of cell proliferation or signaling through the mitogenic cascade in adenoma cells, it increased the rate of apoptosis. Conclusion Reduced BAG-1 expression specifically targets tumor cells to apoptosis and impairs tumorigenesis. Our data implicate BAG-1 as a key player in oncogenic transformation by Raf and identify it as a potential molecular target for cancer treatment.
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Affiliation(s)
- Rudolf Götz
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), Universität Würzburg, Versbacher Straße 5, D-97078 Würzburg, Germany
| | - Boris W Kramer
- Universitäts-Kinderklinik Würzburg, Josef-Schneider-Str. 2, D-97080 Würzburg, Germany
| | - Guadalupe Camarero
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), Universität Würzburg, Versbacher Straße 5, D-97078 Würzburg, Germany
| | - Ulf R Rapp
- Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), Universität Würzburg, Versbacher Straße 5, D-97078 Würzburg, Germany
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Gehring U. Biological activities of HAP46/BAG-1. The HAP46/BAG-1 protein: regulator of HSP70 chaperones, DNA-binding protein and stimulator of transcription. EMBO Rep 2004; 5:148-53. [PMID: 14755308 PMCID: PMC1298994 DOI: 10.1038/sj.embor.7400083] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Accepted: 12/18/2003] [Indexed: 11/08/2022] Open
Abstract
HAP46/BAG-1M and its isoforms affect the protein-folding activities of mammalian HSP70 chaperones. They interact with the ATP-binding domain of HSP70 or HSC70, leaving the substrate-binding site available for further interactions. Trimeric complexes can therefore form with, for example, transcription factors. Moreover, HAP46/BAG-1M and the larger isoform HAP50/BAG-1L bind to DNA non-specifically and enhance transcription in vitro and upon overexpression in intact cells. These factors are linked to positive effects on cell proliferation and survival. This review focuses on DNA-binding activity and transcriptional stimulation by HAP46/BAG-1M, and presents a molecular model for the underlying mechanism. It is proposed that transcription factors are recruited into complexes with HAP46/BAG-1M or HAP50/BAG-1L through HSP70/HSC70 and that response-element-bound complexes that contain HAP46/BAG-1M and/or HAP50/BAG-1L along with HSP70s target and affect the basal transcription machinery.
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Affiliation(s)
- Ulrich Gehring
- Universität Heidelberg, c/o Molekulare Evolution und Genomik, Im Neuenheimer Feld 230, D-69120 Heidelberg, Germany.
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Saito K, Hayano-Saito Y, Maruyama-Funatsuki W, Sato Y, Kato A. Physical mapping and putative candidate gene identification of a quantitative trait locus Ctb1 for cold tolerance at the booting stage of rice. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2004; 109:515-22. [PMID: 15114474 DOI: 10.1007/s00122-004-1667-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2003] [Accepted: 03/20/2004] [Indexed: 05/03/2023]
Abstract
Norin-PL8 is a cold-tolerant variety of rice (Oryza sativa L.) that was developed by introgressing chromosomal segments from a cold-tolerant tropical japonica variety, Silewah, into a template japonica variety, Hokkai241. We previously identified two closely linked quantitative trait loci, Ctb1 and Ctb2, for cold tolerance at the booting stage of Norin-PL8 in the long arm of chromosome 4. We report here the physical mapping of Ctb1 and the identification of the candidate genes. A total of 2,008 segregating individuals were screened for recombination in the Ctb1 region by a PCR-based screening, and a series of near-isogenic lines (NILs) were developed from progenies of recombinants. A comparison of the degrees of cold tolerance of the NILs indicated that Ctb1 is located in the 56-kb region covered by a bacterial artificial chromosome clone, OSJNBa0058 K23, that had been sequenced by the International Rice Genome Sequence Project. We found seven open reading frames (ORFs) in the 56-kb region. Two ORFs encoded receptor-like protein kinases that are possibly involved in signal transduction pathways. Proteins that may be associated with a ubiquitin-proteasome pathway were encoded by three ORFs, two of which encoded F-box proteins and one of which encoded a protein with a BAG domain. The other two ORFs encoded a protein with an OTU domain and an unknown protein. We were also able to show that Ctb1 is likely to be associated with anther length, which is one of major factors in cold tolerance at the booting stage.
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Affiliation(s)
- K Saito
- National Agricultural Research Center for Hokkaido Region, Hitsujigaoka 1, Toyohira, Sapporo, Hokkaido, Japan.
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37
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Pickering BM, Mitchell SA, Spriggs KA, Stoneley M, Willis AE. Bag-1 internal ribosome entry segment activity is promoted by structural changes mediated by poly(rC) binding protein 1 and recruitment of polypyrimidine tract binding protein 1. Mol Cell Biol 2004; 24:5595-605. [PMID: 15169918 PMCID: PMC419896 DOI: 10.1128/mcb.24.12.5595-5605.2004] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Revised: 01/07/2004] [Accepted: 03/26/2004] [Indexed: 11/20/2022] Open
Abstract
We have shown previously that an internal ribosome entry segment (IRES) directs the synthesis of the p36 isoform of Bag-1 and that polypyrimidine tract binding protein 1 (PTB-1) and poly(rC) binding protein 1 (PCBP1) stimulate IRES-mediated translation initiation in vitro and in vivo. Here, a secondary structural model of the Bag-1 IRES has been derived by using chemical and enzymatic probing data as constraints on the RNA folding algorithm Mfold. The ribosome entry window has been identified within this structural model and is located in a region in which many residues are involved in base-pairing interactions. The interactions of PTB-1 and PCBP1 with their cognate binding sites on the IRES disrupt many of the RNA-RNA interactions, and this creates a largely unstructured region of approximately 40 nucleotides that could permit ribosome binding. Mutational analysis of the PTB-1 and PCBP1 binding sites suggests that PCBP1 acts as an RNA chaperone to open the RNA in the vicinity of the ribosome entry window while PTB-1 is probably an essential part of the preinitiation complex.
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Affiliation(s)
- Becky M Pickering
- Department of Biochemistry, University of Leicester, LE1 7RH, United Kingdom
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Abstract
Protein-damaging stresses induce the expression of 'heat-shock proteins', which have essential roles in protecting cells from the potentially lethal effects of stress and proteotoxicity. These stress-protective heat-shock proteins are often overexpressed in cells of various cancers and have been suggested to be contributing factors in tumorigenesis. An underlying basis of oncogenesis is the acquisition and accumulation of mutations that provide the transformed cell with the combined characteristics of deregulated cell proliferation and suppressed cell death. Heat-shock proteins with dual roles as regulators of protein conformation and stress sensors may therefore have intriguing and central roles in both cell proliferation and apoptosis. It has been established that heat-shock proteins exhibit specificity to particular classes of polypeptide substrates and client proteins in vivo, and that chaperones can stabilize mutations that affect the folded conformation. Likewise, overexpression of chaperones has also been shown to protect cells against apoptotic cell death. The involvement of chaperones, therefore, in such diverse roles might suggest novel anticancer therapeutic approaches targeting heat-shock protein function for a broad spectrum of tumor types.
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Affiliation(s)
- Dick D Mosser
- Department of Molecular Biology and Genetics, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
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