1
|
Zeidan Q, Tian JL, Ma J, Eslami F, Hart GW. O-GlcNAcylation of ribosome-associated proteins is concomitant with translational reprogramming during proteotoxic stress. J Biol Chem 2024:107877. [PMID: 39395807 DOI: 10.1016/j.jbc.2024.107877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 09/23/2024] [Accepted: 10/04/2024] [Indexed: 10/14/2024] Open
Abstract
Protein O-GlcNAc modification, similar to phosphorylation, supports cell survival by regulating key processes like transcription, cell division, trafficking, signaling, and stress tolerance. However, its role in protein homeostasis, particularly in protein synthesis, folding, and degradation remains poorly understood. Our previous research shows that O-GlcNAc cycling enzymes associate with the translation machinery during protein synthesis and modify ribosomal proteins. Protein translation is closely linked to 26S proteasome activity, which recycles amino acids and clears misfolded proteins during stress, preventing aggregation and cell death. In this study, we demonstrate that pharmacological perturbation of the proteasome-like that used in cancer treatment- leads to the increased abundance of OGT and OGA in a ribosome-rich fraction, concurrent with O-GlcNAc modification of core translational and ribosome-associated proteins. This interaction is synchronous with eIF2α-dependent translational reprogramming. We also found that protein ubiquitination depends partly on O-GlcNAc metabolism in MEFs, as OGT-depleted cells show decreased ubiquitination under stress. Using an O-GlcNAc-peptide enrichment strategy followed by LC-MS/MS, we identified 84 unique O-GlcNAc sites across 55 proteins, including ribosomal proteins, nucleolar factors, and the 70-kDa heat shock protein family. Hsp70 and OGT colocalize with the translational machinery in an RNA-independent manner, aiding in partial protein translation recovery during sustained stress. O-GlcNAc cycling on ribosome-associated proteins collaborates with Hsp70 to restore protein synthesis during proteotoxicity, suggesting a role in tumor resistance to proteasome inhibitors.
Collapse
Affiliation(s)
- Quira Zeidan
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA
| | - Jie L Tian
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 USA
| | - Junfeng Ma
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore MD 21205 USA
| | - Farzad Eslami
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 USA
| | - Gerald W Hart
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602 USA.
| |
Collapse
|
2
|
Yu ZQ, Carmichael J, Collins GA, D'Agostino MD, Lessard M, Firth HV, Harijan P, Fry AE, Dean J, Zhang J, Kini U, Goldberg AL, Rubinsztein DC. PSMC5 insufficiency and P320R mutation impair proteasome function. Hum Mol Genet 2024; 33:1506-1523. [PMID: 38776958 PMCID: PMC11336065 DOI: 10.1093/hmg/ddae085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 05/03/2024] [Accepted: 05/08/2024] [Indexed: 05/25/2024] Open
Abstract
The ubiquitin-proteasome system mediates the degradation of a wide variety of proteins. Proteasome dysfunction is associated with neurodegenerative diseases and neurodevelopmental disorders in humans. Here we identified mutations in PSMC5, an AAA ATPase subunit of the proteasome 19S regulatory particle, in individuals with neurodevelopmental disorders, which were initially considered as variants of unknown significance. We have now found heterozygotes with the following mutations: P320R (6 individuals), R325W, Q160A, and one nonsense mutation at Q69. We focused on understanding the functional consequence of PSMC5 insufficiency and the P320R mutation in cells and found that both impair proteasome function and activate apoptosis. Interestingly, the P320R mutation impairs proteasome function by weakening the association between the 19S regulatory particle and the 20S core particle. Our study supports that proteasome dysfunction is the pathogenic cause of neurodevelopmental disorders in individuals carrying PSMC5 variants.
Collapse
Affiliation(s)
- Zhong-Qiu Yu
- Cambridge Institute for Medical Research, The Keith Peters Building, Department of Medical Genetics, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
- UK Dementia Research Institute, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
| | - Jenny Carmichael
- Department of Clinical Genetics, Cambridge University Hospitals NHS Foundation Trust, Box 134, Addenbrooke’s Hospital, Cambridge CB2 0QQ, United Kingdom
| | - Galen A Collins
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, United States
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, 32 Creelman Street, Starkville MS 39762, United States
| | - Maria Daniela D'Agostino
- Division of Medical Genetics, Department of Specialised Medicine, McGill University Health Centre, 1001 Decarie Boulevard, Montreal, Quebec, H4A 3J1, Canada
- Care for Rare Canada Consortium, Children’s Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, K1H 8L1, ON, Canada
| | - Mathieu Lessard
- Division of Medical Genetics, Department of Specialised Medicine, McGill University Health Centre, 1001 Decarie Boulevard, Montreal, Quebec, H4A 3J1, Canada
- Care for Rare Canada Consortium, Children’s Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, K1H 8L1, ON, Canada
| | - Helen V Firth
- Department of Clinical Genetics, Cambridge University Hospitals NHS Foundation Trust, Box 134, Addenbrooke’s Hospital, Cambridge CB2 0QQ, United Kingdom
| | - Pooja Harijan
- Department of Paediatric Neurosciences, Box 107, Child development centre, Addenbrooke’s Hospital, Hills Road, Cambridge CB2 0QQ, United Kingdom
| | - Andrew E Fry
- All Wales Medical Genomics Service, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, United Kingdom
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff CF14 4XN, United Kingdom
| | - John Dean
- The School of Medicine, Medical Sciences and Nutrition, Polwarth Building, University of Aberdeen, Aberdeen, AB25 2ZD, United Kingdom
| | - Jiuchun Zhang
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, United States
| | - Usha Kini
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford & Radcliffe Department of Medicine, University of Oxford, Windmill Road, Oxford, OX3 7HE, United Kingdom
| | - Alfred L Goldberg
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, United States
| | - David C Rubinsztein
- Cambridge Institute for Medical Research, The Keith Peters Building, Department of Medical Genetics, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
- UK Dementia Research Institute, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
| |
Collapse
|
3
|
Alhasan BA, Morozov AV, Guzhova IV, Margulis BA. The ubiquitin-proteasome system in the regulation of tumor dormancy and recurrence. Biochim Biophys Acta Rev Cancer 2024; 1879:189119. [PMID: 38761982 DOI: 10.1016/j.bbcan.2024.189119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2024] [Revised: 05/12/2024] [Accepted: 05/15/2024] [Indexed: 05/20/2024]
Abstract
Tumor recurrence is a mechanism triggered in sparse populations of cancer cells that usually remain in a quiescent state after strict stress and/or therapeutic factors, which is affected by a variety of autocrine and microenvironmental cues. Despite thorough investigations, the biology of dormant and/or cancer stem cells is still not fully elucidated, as for the mechanisms of their reawakening, while only the major molecular patterns driving the relapse process have been identified to date. These molecular patterns profoundly interfere with the elements of cellular proteostasis systems that support the efficiency of the recurrence process. As a major proteostasis machinery, we review the role of the ubiquitin-proteasome system (UPS) in tumor cell dormancy and reawakening, devoting particular attention to the functions of its components, E3 ligases, deubiquitinating enzymes and proteasomes in cancer recurrence. We demonstrate how UPS components functionally or mechanistically interact with the pivotal proteins implicated in the recurrence program and reveal that modulators of the UPS hold promise to become an efficient adjuvant therapy for eradicating refractory tumor cells to impede tumor relapse.
Collapse
Affiliation(s)
- Bashar A Alhasan
- Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Ave. 4, 194064 St. Petersburg, Russia.
| | - Alexey V Morozov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov Street 32, 119991 Moscow, Russia.
| | - Irina V Guzhova
- Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Ave. 4, 194064 St. Petersburg, Russia.
| | - Boris A Margulis
- Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Ave. 4, 194064 St. Petersburg, Russia.
| |
Collapse
|
4
|
Cisneros B, García-Aguirre I, De Ita M, Arrieta-Cruz I, Rosas-Vargas H. Hutchinson-Gilford Progeria Syndrome: Cellular Mechanisms and Therapeutic Perspectives. Arch Med Res 2023; 54:102837. [PMID: 37390702 DOI: 10.1016/j.arcmed.2023.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 05/26/2023] [Accepted: 06/14/2023] [Indexed: 07/02/2023]
Abstract
In humans, aging is characterized by a gradual decline of physical and psychological functions, with the concomitant onset of chronic-degenerative diseases, which ultimately lead to death. The study of Hutchinson-Gilford progeria syndrome (HGPS), a premature aging disorder that recapitulates several features of natural aging, has provided important insights into deciphering the aging process. The genetic origin of HGPS is a de novo point mutation in the LMNA gene that drives the synthesis of progerin, mutant version of lamin A. Progerin is aberrantly anchored to the nuclear envelope disrupting a plethora of molecular processes; nonetheless, how progerin exerts a cascade of deleterious alterations at the cellular and systemic levels is not fully understood. Over the past decade, the use of different cellular and animal models for HGPS has allowed the identification of the molecular mechanisms underlying HGPS, paving the way towards the development of therapeutic treatments against the disease. In this review, we present an updated overview of the biology of HGPS, including its clinical features, description of key cellular processes affected by progerin (nuclear morphology and function, nucleolar activity, mitochondrial function, protein nucleocytoplasmic trafficking and telomere homeostasis), as well as discussion of the therapeutic strategies under development.
Collapse
Affiliation(s)
- Bulmaro Cisneros
- Genetics and Molecular Biology Department, Research and Advanced Studies Center, National Polytechnical Institute, Mexico City, Mexico
| | - Ian García-Aguirre
- Genetics and Molecular Biology Department, Research and Advanced Studies Center, National Polytechnical Institute, Mexico City, Mexico; Bioengineering Department, School of Engineering and Sciences, Tecnológico de Monterrey, Mexico City, Mexico
| | - Marlon De Ita
- Genetics and Molecular Biology Department, Research and Advanced Studies Center, National Polytechnical Institute, Mexico City, Mexico; Medical Research Unit in Human Genetics, Pediatrics Hospital, 21st Century National Medical Center, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - Isabel Arrieta-Cruz
- Basic Research Department, Research Direction, National Institute of Geriatrics, Ministry of Health, Mexico City, Mexico
| | - Haydeé Rosas-Vargas
- Medical Research Unit in Human Genetics, Pediatrics Hospital, 21st Century National Medical Center, Instituto Mexicano del Seguro Social, Mexico City, Mexico.
| |
Collapse
|
5
|
Past, Present, and a Glance into the Future of Multiple Myeloma Treatment. Pharmaceuticals (Basel) 2023; 16:ph16030415. [PMID: 36986514 PMCID: PMC10056051 DOI: 10.3390/ph16030415] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/28/2023] [Accepted: 03/02/2023] [Indexed: 03/11/2023] Open
Abstract
Multiple myeloma (MM) is a challenging hematological cancer which typically grows in bone marrow. MM accounts for 10% of hematological malignancies and 1.8% of cancers. The recent treatment strategies have significantly improved progression-free survival for MM patients in the last decade; however, a relapse for most MM patients is inevitable. In this review we discuss current treatment, important pathways for proliferation, survival, immune suppression, and resistance that could be targeted for future treatments.
Collapse
|
6
|
Target Gene Diversity of the Nrf1-MafG Transcription Factor Revealed by a Tethered Heterodimer. Mol Cell Biol 2022; 42:e0052021. [PMID: 35129372 DOI: 10.1128/mcb.00520-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Members of the cap'n'collar (CNC) family of transcription factors, including Nrf1 and Nrf2, heterodimerize with small Maf proteins (MafF, MafG and MafK) and regulate target gene expression through CNC-sMaf binding elements (CsMBEs). We recently developed a unique tethered dimer assessment system combined with small Maf triple knockout fibroblasts, which enabled the characterization of specific CNC-sMaf heterodimer functions. In this study, we evaluated the molecular function of the tethered Nrf1-MafG (T-N1G) heterodimer. We found that T-N1G activates the expression of proteasome subunit genes, well-known Nrf1 target genes, and binds specifically to CsMBEs in the proximity of these genes. T-N1G was also found to activate genes involved in proteostasis-related pathways, including endoplasmic reticulum-associated degradation, chaperone, and ubiquitin-mediated degradation pathways, indicating that the Nrf1-MafG heterodimer regulates a wide range of proteostatic stress response genes. By taking advantage of this assessment system, we found that Nrf1 has the potential to activate canonical Nrf2 target cytoprotective genes when strongly induced. Our results also revealed that transposable SINE B2 repeats harbor CsMBEs with high frequency and contribute to the target gene diversity of CNC-sMaf transcription factors.
Collapse
|
7
|
Li J, Jin S, Barati MT, Rane S, Lin Q, Tan Y, Cai L, Rane MJ. ERK and p38 MAPK inhibition controls NF-E2 degradation and profibrotic signaling in renal proximal tubule cells. Life Sci 2021; 287:120092. [PMID: 34715142 PMCID: PMC8665041 DOI: 10.1016/j.lfs.2021.120092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 10/09/2021] [Accepted: 10/21/2021] [Indexed: 12/19/2022]
Abstract
Aims: Transforming growth factor-β (TGF-β) mediates fibrotic manifestations of diabetic nephropathy. We demonstrated proteasomal degradation of anti-fibrotic protein, nuclear factor-erythroid derived 2 (NF-E2), in TGF-β treated human renal proximal tubule (HK-11) cells and in diabetic mouse kidneys. The current study examined the role of mitogen-activated protein kinase (MAPK) pathways in mediating NF-E2 proteasomal degradation and stimulating profibrotic signaling in HK-11 cells. Main methods: HK-11 cells were pretreated with vehicle or appropriate proteasome and MAPK inhibitors, MG132 (0.5 μM), SB203580 (1 μM), PD98059 (25 μM) and SP600125 (10 μM), respectively, followed by treatment with/without TGF-β (10 ng/ml, 24 h). Cell lysates and kidney homogenates from FVB and OVE26 mice treated with/without MG132 were immunoblotted with appropriate antibodies. pUse vector and pUse-NF-E2 cDNA were transfected in HK-11 cells and effects of TGF-β on JNK MAPK phosphorylation (pJNK) was examined. Key findings: We demonstrated activation of p38, ERK, and JNK MAPK pathways in TGF-β treated HK-11 cells. Dual p38 and ERK MAPK blockade prevented TGF-β-induced pSer82Hsp27, fibronectin and connective tissue growth factor (CTGF) expression while preserving NF-E2 expression. Blockade of JNK MAPK inhibited TGF-β-induced CTGF expression without preserving NF-E2 expression. MG132 treatment prevented TGF-β-induced pJNK in HK-11 cells and in type 1 diabetic OVE26 mouse kidneys, demonstrating that TGF-β- and diabetes-induced pJNK occurs downstream of proteasome activation. A direct role for NF-E2 in modulating pJNK activation was demonstrated by NF-E2 over-expression. Significance: ERK and p38 MAPK promotes NF-E2 proteasomal degradation while proteasome activation promotes pJNK and profibrotic signaling in renal proximal tubule cells.
Collapse
Affiliation(s)
- Jia Li
- Department of Medicine, Division Nephrology, University of Louisville, Louisville, KY 40292, USA; Department of Nephrology, the First Hospital of Jilin University, Changchun, Jilin 130021, China; Pediatric Research Institute, Department of Pediatrics, University of Louisville School of Medicine, Louisville, KY 40292, USA
| | - Shunying Jin
- Department of Medicine, Division Nephrology, University of Louisville, Louisville, KY 40292, USA
| | - Michelle T Barati
- Department of Medicine, Division Nephrology, University of Louisville, Louisville, KY 40292, USA
| | - Sanjana Rane
- Department of Medicine, Division Nephrology, University of Louisville, Louisville, KY 40292, USA
| | - Qian Lin
- Pediatric Research Institute, Department of Pediatrics, University of Louisville School of Medicine, Louisville, KY 40292, USA
| | - Yi Tan
- Pediatric Research Institute, Department of Pediatrics, University of Louisville School of Medicine, Louisville, KY 40292, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40292, USA
| | - Lu Cai
- Pediatric Research Institute, Department of Pediatrics, University of Louisville School of Medicine, Louisville, KY 40292, USA; Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, KY 40292, USA; Departments of Radiation Oncology, University of Louisville School of Medicine, Louisville, KY 40292, USA
| | - Madhavi J Rane
- Department of Medicine, Division Nephrology, University of Louisville, Louisville, KY 40292, USA; Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292, USA.
| |
Collapse
|
8
|
Baldan S, Meriin AB, Yaglom J, Alexandrov I, Varelas X, Xiao ZXJ, Sherman MY. The Hsp70-Bag3 complex modulates the phosphorylation and nuclear translocation of Hippo pathway protein Yap. J Cell Sci 2021; 134:273417. [PMID: 34761265 DOI: 10.1242/jcs.259107] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 10/28/2021] [Indexed: 11/20/2022] Open
Abstract
Protein abnormalities can accelerate aging causing protein misfolding diseases, and various adaptive responses have evolved to relieve proteotoxicity. To trigger these responses, cells must detect the buildup of aberrant proteins. Previously we demonstrated that the Hsp70-Bag3 (HB) complex senses the accumulation of defective ribosomal products, stimulating signaling pathway proteins, such as stress kinases or the Hippo pathway kinase LATS1. Here, we studied how Bag3 regulates the ability for LATS1 to regulate its key downstream target YAP (also known as YAP1). In naïve cells, Bag3 recruited a complex of LATS1, YAP and the scaffold AmotL2, which links LATS1 and YAP. Upon inhibition of the proteasome, AmotL2 dissociated from Bag3, which prevented phosphorylation of YAP by LATS1, and led to consequent nuclear YAP localization together with Bag3. Mutations in Bag3 that enhanced its translocation into nucleus also facilitated nuclear translocation of YAP. Interestingly, Bag3 also controlled YAP nuclear localization in response to cell density, indicating broader roles beyond proteotoxic signaling responses for Bag3 in the regulation of YAP. These data implicate Bag3 as a regulator of Hippo pathway signaling, and suggest mechanisms by which proteotoxic stress signals are propagated.
Collapse
Affiliation(s)
- Simone Baldan
- Department of Molecular Biology, Ariel University, Ariel 4077625, Israel
| | - Anatoli B Meriin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02215, USA
| | - Julia Yaglom
- Department of Molecular Biology, Ariel University, Ariel 4077625, Israel
| | | | - Xaralabos Varelas
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02215, USA
| | | | - Michael Y Sherman
- Department of Molecular Biology, Ariel University, Ariel 4077625, Israel
| |
Collapse
|
9
|
Sherman MY, Gabai V. The role of Bag3 in cell signaling. J Cell Biochem 2021; 123:43-53. [PMID: 34297413 DOI: 10.1002/jcb.30111] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/05/2021] [Accepted: 07/08/2021] [Indexed: 12/31/2022]
Abstract
Bag3 has been implicated in a wide variety of physiological processes from autophagy to aggresome formation and from cell transformation to survival. We argue that involvement of Bag3 in many of these processes is due to its distinct function in cell signaling. The structure of Bag3 suggests that it can serve as a scaffold that links molecular chaperones Hsp70 and small Hsps with components of a variety of signaling pathways. Major protein-protein interaction motifs of Bag3 that recruit components of signaling pathways are WW domain and PXXP motif that interacts with SH3-domain proteins. Furthermore, Hsp70-Bag3 appears to be a sensor of abnormal polypeptides during the proteotoxic stress. It also serves as a sensor of a mechanical force during mechanotransduction. Common feature of these and probably certain other sensory mechanisms is that they represent responses to specific kinds of abnormal proteins, i.e. unfolded filamin A in case of mechanotransduction or stalled translating polypeptides in case of sensing proteasome inhibition. Overall Hsp70-Bag3 module represents a novel signaling node that responds to multiple stimuli and controls multiple physiological processes.
Collapse
Affiliation(s)
| | - Vladimir Gabai
- Department of Biochemistry, Boston University, Boston, Massachusetts, USA
| |
Collapse
|
10
|
Selection of CHO host and recombinant cell pools by inhibition of the proteasome results in enhanced product yields and cell specific productivity. J Biotechnol 2021; 337:35-45. [PMID: 34171439 DOI: 10.1016/j.jbiotec.2021.06.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 05/14/2021] [Accepted: 06/19/2021] [Indexed: 11/23/2022]
Abstract
Chinese hamster ovary (CHO) cells are the leading mammalian cell expression platform for biotherapeutic recombinant molecules yet some proteins remain difficult to express (DTE) in this, and other, systems. In recombinant cell lines expressing DTE proteins, cellular processes to restore proteostasis can be triggered when the folding and modification capabilities are exceeded, including the unfolded protein response and ER-associated degradation (ERAD) and proteasomal degradation. We therefore investigated whether the proteasome activity of CHO cells was linked to their ability to produce recombinant proteins. We found cell lines with diverse monoclonal antibody (mAb) productivity show different susceptibilities to inhibitors of proteasome activity. Subsequently, we applied selective pressure using proteasome inhibitors on mAb producing cells to determine the impact on cell growth and recombinant protein production, and to apply proteasome selective pressure above that of a metabolic selection marker during recombinant cell pool construction. The presence of proteasome inhibitors during cell pool construction expressing two different model molecules, including a DTE Fc-fusion protein, resulted in the generation of cell pools with enhanced productivity. The increased productivities, and ability to select for higher producing cells, has potential to improve clonal selection during upstream processes of DTE proteins.
Collapse
|
11
|
Mitogen-activated protein kinases are involved in cucurbitacin D-induced antitumor effects on adult T-cell leukemia cells. Invest New Drugs 2020; 39:122-130. [PMID: 32914311 DOI: 10.1007/s10637-020-00997-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/04/2020] [Indexed: 10/23/2022]
Abstract
Adult T cell leukemia (ATL) is an aggressive and malignant blood disease. We previously reported that steroid-structured cucurbitacin D (CuD) induces apoptosis in ATL cells. In this study, we investigated the effects of mitogen-activated protein kinase (MAPK) signaling inhibitors on CuD-induced cell death in peripheral blood lymphocytes (PBLs) isolated from ATL/acute lymphoblastic leukemia (ALL) patients and two human leukemia cell lines (MT-1 and MT-4). PBLs were isolated from an ATL/ALL patient as well as from a healthy donor. Cell surface markers were examined using flow cytometry. Serum cytokine levels were estimated using LEGENDplex or analyzed at the Center for Clinical and Translational Research of Kyushu University Hospital. Cell proliferation was assessed using the Cell Titer-Glo luminescent cell viability assay. Protein expression was determined by western blotting. PBLs from patients highly expressed CD4 and CD5. Serum from the patient contained high levels of interleukin (IL)-8, IL-10, IL-18, and interferon-γ compared to the healthy donor. CuD-induced cell death was enhanced by the mitogen-activated protein kinase kinase (MEK)1/2 inhibitor U0126. However, a c-Jun N-terminal kinase (JNK) inhibitor prevented CuD-induced cell death. Immunoblot analyses revealed that CuD reduced the phosphorylation of extracellular signal-regulated kinase (ERK), p38, and JNK, and co-treatment with CuD and U0126 did not affect the phosphorylation of ERK. MEK1/2 and p38 inhibitors enhanced CuD-induced cell death, and U0126 enhanced the CuD-induced de-phosphorylation of ERK in MT-1 and MT-4 cells. We conclude that CuD reduces ERK activation, resulting in enhanced antitumor effects on leukemic cells.
Collapse
|
12
|
Aminian F, hejazi M, Birjandi SC. Low-Intensity Blood Flow Restriction Training Does Not Modulate Myostatin Concentration in Elderly Females. MEDICAL LABORATORY JOURNAL 2020. [DOI: 10.29252/mlj.14.5.30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
|
13
|
Zhu X, Wang F, Wu X, Li Z, Wang Z, Ren X, Zhou Y, Song F, Liang Y, Zeng Z, Liao W, Ding Y, Liao W, Liang L. FBX8 promotes metastatic dormancy of colorectal cancer in liver. Cell Death Dis 2020; 11:622. [PMID: 32796813 PMCID: PMC7427987 DOI: 10.1038/s41419-020-02870-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Revised: 07/28/2020] [Accepted: 07/28/2020] [Indexed: 12/17/2022]
Abstract
Patients with colorectal cancer (CRC) often develop malignant regrowth of metastatic dormant tumor cells in liver years after primary treatment. FBX8 is involved in suppressing tumor metastasis. Short-term chemotherapy experiments and liver metastasis mice model of orthotopic injection into the cecum were performed to construct the dormant models. GST-pull-down assay, Co-IP and immunofluorescence were used to confirm the bindings among FBX8 and its substrates. FBX8 upregulated the expression of epithelial and stemness markers, while downregulated the expression of mesenchymal and proliferative markers associated with tumor cell dormancy. FBX8 promoted the maintenance of metastatic dormancy of CRC cells. Mechanistically, FBX8 directly bound to HIF-1α, CDK4 and C-myc through its Sec7 domain and led to the ubiquitin degradation of these proteins, thereby inhibiting cell cycle progression, proliferation, angiogenesis, and metastasis. Clinically, FBX8 expression was negatively correlated with the HIF-1α, CDK4, and c-Myc in CRC tissues. Our study reveals a novel mechanism of FBX8 in regulating tumor metastatic dormancy in liver and provides new strategies for the treatment of CRC metastasis.
Collapse
Affiliation(s)
- Xiaohui Zhu
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China.,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Feifei Wang
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China.,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Xuehui Wu
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China.,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Zhou Li
- The First Clinical Medical Department, Southern Medical University, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Zhizhi Wang
- Department of Thoracic Surgery, Nanfang Hospital, Southern Medical University, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Xiaoli Ren
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China.,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Yangshu Zhou
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China.,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Fuyao Song
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China.,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Yunshi Liang
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China.,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Zhicheng Zeng
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China.,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Wangjun Liao
- Department of Oncology, Nanfang Hospital, Southern Medical University, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Yanqing Ding
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China.,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China
| | - Wenting Liao
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China. .,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China.
| | - Li Liang
- Department of Pathology, Nanfang Hospital and Basic Medical College, Southern Medical University, Guangzhou, 510515, Guangdong Province, People's Republic of China. .,Guangdong Province Key Laboratory of Molecular Tumor Pathology, 510515, Guangzhou, Guangdong Province, People's Republic of China.
| |
Collapse
|
14
|
Sari G, Okat Z, Sahin A, Karademir B. Proteasome Inhibitors in Cancer Therapy and their Relation to Redox Regulation. Curr Pharm Des 2019; 24:5252-5267. [PMID: 30706779 DOI: 10.2174/1381612825666190201120013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 01/25/2019] [Indexed: 01/23/2023]
Abstract
Redox homeostasis is important for the maintenance of cell survival. Under physiological conditions, redox system works in a balance and involves activation of many signaling molecules. Regulation of redox balance via signaling molecules is achieved by different pathways and proteasomal system is a key pathway in this process. Importance of proteasomal system on signaling pathways has been investigated for many years. In this direction, many proteasome targeting molecules have been developed. Some of them are already in the clinic for cancer treatment and some are still under investigation to highlight underlying mechanisms. Although there are many studies done, molecular mechanisms of proteasome inhibitors and related signaling pathways need more detailed explanations. This review aims to discuss redox status and proteasomal system related signaling pathways. In addition, cancer therapies targeting proteasomal system and their effects on redox-related pathways have been summarized.
Collapse
Affiliation(s)
- Gulce Sari
- Department of Biochemistry, Faculty of Medicine / Genetic and Metabolic Diseases Research and Investigation Center, Marmara University, 34854 Maltepe, Istanbul, Turkey.,Department of Genetics and Bioengineering, Faculty of Engineering, Okan University, 34959, Tuzla, I stanbul, Turkey
| | - Zehra Okat
- Department of Biochemistry, Faculty of Medicine / Genetic and Metabolic Diseases Research and Investigation Center, Marmara University, 34854 Maltepe, Istanbul, Turkey
| | - Ali Sahin
- Department of Biochemistry, Faculty of Medicine / Genetic and Metabolic Diseases Research and Investigation Center, Marmara University, 34854 Maltepe, Istanbul, Turkey
| | - Betul Karademir
- Department of Biochemistry, Faculty of Medicine / Genetic and Metabolic Diseases Research and Investigation Center, Marmara University, 34854 Maltepe, Istanbul, Turkey
| |
Collapse
|
15
|
Zhou P, Zhu M, Zhang C, Chen D, Zheng H. International Publication Trends in Proteasome Inhibitors: From Tools for Cell Biologists to Anticancer Agents. LETT DRUG DES DISCOV 2019. [DOI: 10.2174/1570180816666190325165106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
There has been increased interest in the research of proteasome inhibitors
for more than two decades. Hotspots in this field are constantly changing.
Objective:
This study aimed to investigate trends in proteasome inhibitors research from 1992 to
2018 and compare the contributions of such research from different countries and authors.
Methods:
We used Excel 2013 and VoSviewer to analyze bibliometric data on the subject of
proteasome inhibitors, including the number of publications, citations frequency, H-index, and
country contributions and hotspots (keywords of popular scientific fields).
Results:
A total of 3646 articles were included. The USA contributed the largest percentage of
articles (1742), with the most citations (90666) and the highest H-index (139). The journal Blood had
the most articles. Dana Farber Cancer Institute and Millennium Pharmaceuticals Incorporation were
the most contributive institutions. Keywords could be divided into three clusters: Basic experiment,
clinical research, and others.
Conclusion:
The number of proteasome inhibitors articles has been increasing for the past 27 years.
The USA made the largest contribution in this field. Recent studies on the topic of “carfilzomib” are
relatively new and should be closely followed in proteasome inhibitors research.
Collapse
Affiliation(s)
- Peng Zhou
- Department of Otorhinolaryngology-Head and Neck Surgery, Changhai Hospital, Second Military Medical University, Shanghai 200433, China
| | - Minhui Zhu
- Department of Otorhinolaryngology-Head and Neck Surgery, Changhai Hospital, Second Military Medical University, Shanghai 200433, China
| | - Caiyun Zhang
- Department of Otorhinolaryngology-Head and Neck Surgery, Changhai Hospital, Second Military Medical University, Shanghai 200433, China
| | - Donghui Chen
- Department of Otorhinolaryngology-Head and Neck Surgery, Changhai Hospital, Second Military Medical University, Shanghai 200433, China
| | - Hongliang Zheng
- Department of Otorhinolaryngology-Head and Neck Surgery, Changhai Hospital, Second Military Medical University, Shanghai 200433, China
| |
Collapse
|
16
|
Prince T, Ackerman A, Cavanaugh A, Schreiter B, Juengst B, Andolino C, Danella J, Chernin M, Williams H. Dual targeting of HSP70 does not induce the heat shock response and synergistically reduces cell viability in muscle invasive bladder cancer. Oncotarget 2018; 9:32702-32717. [PMID: 30220976 PMCID: PMC6135696 DOI: 10.18632/oncotarget.26021] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 08/13/2018] [Indexed: 12/13/2022] Open
Abstract
Muscle invasive bladder cancer (MIBC) is a common malignancy and major cause of morbidity worldwide. Over the last decade mortality rates for MIBC have not decreased as compared to other cancers indicating a need for novel strategies. The molecular chaperones HSP70 and HSP90 fold and maintain the 3-dimensional structures of numerous client proteins that signal for cancer cell growth and survival. Inhibition of HSP70 or HSP90 results in client protein degradation and associated oncogenic signaling. Here we targeted HSP70 and HSP90 with small molecule inhibitors that trap or block each chaperone in a low client-affinity “open” conformation. HSP70 inhibitors, VER155008 (VER) and MAL3-101 (MAL), along with HSP90 inhibitor, STA-9090 (STA), were tested alone and in combination for their ability to reduce cell viability and alter protein levels in 4 MIBC cell lines. When combined, VER+MAL synergistically reduced cell viability in each MIBC cell line while not inducing expression of heat shock proteins (HSPs). STA+MAL also synergistically reduced cell viability in each cell line but induced expression of cytoprotective HSPs indicating the merits of targeting HSP70 with VER+MAL. Additionally, we observed that STA induced the expression of the stress-related transcription factor HSF2 while reducing levels of the co-chaperone TTI1.
Collapse
Affiliation(s)
- Thomas Prince
- Urology Department, Geisinger Clinic, Danville, 17822 PA, USA.,Weis Center for Research, Geisinger Clinic, Danville, 17822 PA, USA
| | - Andrew Ackerman
- Weis Center for Research, Geisinger Clinic, Danville, 17822 PA, USA
| | - Alice Cavanaugh
- Weis Center for Research, Geisinger Clinic, Danville, 17822 PA, USA
| | | | - Brendon Juengst
- Weis Center for Research, Geisinger Clinic, Danville, 17822 PA, USA
| | - Chaylen Andolino
- Biology Department, Bucknell University, Lewisburg, 17837 PA, USA
| | - John Danella
- Urology Department, Geisinger Clinic, Danville, 17822 PA, USA
| | - Mitch Chernin
- Biology Department, Bucknell University, Lewisburg, 17837 PA, USA
| | - Heinric Williams
- Urology Department, Geisinger Clinic, Danville, 17822 PA, USA.,Weis Center for Research, Geisinger Clinic, Danville, 17822 PA, USA
| |
Collapse
|
17
|
Hsp70-Bag3 complex is a hub for proteotoxicity-induced signaling that controls protein aggregation. Proc Natl Acad Sci U S A 2018; 115:E7043-E7052. [PMID: 29987014 DOI: 10.1073/pnas.1803130115] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Protein abnormalities in cells are the cause of major pathologies, and a number of adaptive responses have evolved to relieve the toxicity of misfolded polypeptides. To trigger these responses, cells must detect the buildup of aberrant proteins which often associate with proteasome failure, but the sensing mechanism is poorly understood. Here we demonstrate that this mechanism involves the heat shock protein 70-Bcl-2-associated athanogene 3 (Hsp70-Bag3) complex, which upon proteasome suppression responds to the accumulation of defective ribosomal products, preferentially recognizing the stalled polypeptides. Components of the ribosome quality control system LTN1 and VCP and the ribosome-associated chaperone NAC are necessary for the interaction of these species with the Hsp70-Bag3 complex. This complex regulates important signaling pathways, including the Hippo pathway effectors LATS1/2 and the p38 and JNK stress kinases. Furthermore, under proteotoxic stress Hsp70-Bag3-LATS1/2 signaling regulates protein aggregation. We established that the regulated step was the emergence and growth of abnormal protein oligomers containing only a few molecules, indicating that aggregation is regulated at very early stages. The Hsp70-Bag3 complex therefore functions as an important signaling node that senses proteotoxicity and triggers multiple pathways that control cell physiology, including activation of protein aggregation.
Collapse
|
18
|
Wilhelm T, Bick F, Peters K, Mohta V, Tirosh B, Patterson JB, Kharabi-Masouleh B, Huber M. Infliction of proteotoxic stresses by impairment of the unfolded protein response or proteasomal inhibition as a therapeutic strategy for mast cell leukemia. Oncotarget 2017; 9:2984-3000. [PMID: 29423023 PMCID: PMC5790440 DOI: 10.18632/oncotarget.23354] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 12/03/2017] [Indexed: 01/05/2023] Open
Abstract
The intensity and duration of endoplasmic reticulum (ER) stress converts the unfolded protein response (UPR) from an adaptive into a terminal response. The first regulates homeostasis, the latter triggers apoptosis. Cells that rapidly proliferate and possess developed secretory capabilities, such as leukemia cells, depend on an efficiently operating UPR to maintain proteostasis. Activation of terminal UPR by either blockade of adaptive UPR or exaggeration of ER stress has been explored as a novel approach in cancer therapy. For mast cell leukemia (MCL) the efficacy of both approaches, by utilizing the KITV560G,D816V-positive MCL cell line HMC-1.2, was investigated. We show that HMC-1.2 cells display a tonic activation of the IRE1α arm of the UPR, which constitutively generates spliced XBP1. Inhibition of IRE1α by different types of inhibitors (MKC-8866, STF-083010, and KIRA6) suppressed proliferation at concentrations needed for blockade of IRE1α-mediated XBP1 splicing. At higher concentrations, these inhibitors triggered an apoptotic response. Blocking the proteasome by bortezomib, which confers an exaggerated UPR, resulted in a marked cytotoxic response. Bortezomib treatment also caused activation of the kinase JNK, which played a pro-proliferative and anti-apoptotic role. Hence, the combination of bortezomib with a JNK inhibitor synergized to induce cell death. In summary, the UPR can be addressed as an effective therapeutic target against KITD816V-positive MCL.
Collapse
Affiliation(s)
- Thomas Wilhelm
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Fabian Bick
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Kerstin Peters
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Vrinda Mohta
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Boaz Tirosh
- The Institute of Drug Research, The Hebrew University of Jerusalem, Jerusalem, Israel
| | | | - Behzad Kharabi-Masouleh
- Department of Hematology, Oncology, Hemostaseology and Stem Cell Transplantation, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Michael Huber
- Institute of Biochemistry and Molecular Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
| |
Collapse
|
19
|
Guo KY, Han L, Li X, Yang AV, Lu J, Guan S, Li H, Yu Y, Zhao Y, Yang J, Zhang H. Novel proteasome inhibitor delanzomib sensitizes cervical cancer cells to doxorubicin-induced apoptosis via stabilizing tumor suppressor proteins in the p53 pathway. Oncotarget 2017; 8:114123-114135. [PMID: 29371974 PMCID: PMC5768391 DOI: 10.18632/oncotarget.23166] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 11/28/2017] [Indexed: 02/06/2023] Open
Abstract
Cervical cancer, the third most commonly occurring cancer, is the second leading cause of cancer related mortality among women. Aberrant ubiquitination and proteasome activity, both human papillomavirus and tumor derived, have been shown to contribute to tumor angiogenesis, proliferation, and invasion in many cancers, including cervical cancer. Thus, small molecule proteasome inhibitors are a potential and strategic treatment option for cervical cancer. In this study, novel proteasome inhibitor delanzomib (CEP-18770) exhibited potent pro-apoptotic and cytotoxic effects on a panel of cervical cancer cell lines by blocking proteasomal activity. Delanzomib also significantly sensitized cervical cancer cells to treatment of doxorubicin (Dox), a traditional chemotherapeutic agent. Furthermore, proteasome inhibition revealed stabilization of p53 and p53 transcriptional targets and induction of p38/JNK phosphorylation. Additionally, delanzomib worked synergistically with Dox to further upregulate p53 and its downstream targets and enhanced Dox-induced p38 phosphorylation. Our study strongly supports the 26S proteasome as a potential therapeutic target in cervical cancer and proteasome inhibition by delanzomib may be a potential treatment strategy for cervical cancer patients.
Collapse
Affiliation(s)
- Kevin Y Guo
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.,Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lili Han
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.,Department of Gynecology, People's Hospital of Xinjiang Uyghur Autonomous Region, Urumqi, Xinjiang 830001, China
| | - Xinyu Li
- Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Andrew V Yang
- Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jiaxiong Lu
- Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Shan Guan
- Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hui Li
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yang Yu
- Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yanling Zhao
- Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jianhua Yang
- Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hong Zhang
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.,Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY 10021, USA
| |
Collapse
|
20
|
Chronically stressed or stress-preconditioned neurons fail to maintain stress granule assembly. Cell Death Dis 2017; 8:e2788. [PMID: 28492545 PMCID: PMC5520719 DOI: 10.1038/cddis.2017.199] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 03/31/2017] [Accepted: 05/04/2017] [Indexed: 12/18/2022]
Abstract
Dysregulation of stress granules (SGs) and their resident proteins contributes to pathogenesis of a number of (neuro)degenerative diseases. Phosphorylation of eIF2α is an event integrating different types of cellular stress and it is required for SG assembly. Phosphorylated eIF2α (p-eIF2α) is upregulated in the nervous system in some neurodegenerative conditions. We found that increasing p-eIF2α level by proteasomal inhibition in cultured cells, including mouse and human neurons, before a SG-inducing stress ('stress preconditioning'), limits their ability to maintain SG assembly. This is due to upregulation of PP1 phosphatase regulatory subunits GADD34 and/or CReP in preconditioned cells and early decline of p-eIF2α levels during subsequent acute stress. In two model systems with constitutively upregulated p-eIF2α, mouse embryonic fibroblasts lacking CReP and brain neurons of tau transgenic mice, SG formation was also impaired. Thus, neurons enduring chronic stress or primed by a transient mild stress fail to maintain p-eIF2α levels following subsequent acute stress, which would compromise protective function of SGs. Our findings provide experimental evidence on possible loss of function for SGs in certain neurodegenerative diseases.
Collapse
|
21
|
Csizmadia V, Hales P, Tsu C, Ma J, Chen J, Shah P, Fleming P, Senn JJ, Kadambi VJ, Dick L, Wolenski FS. Proteasome inhibitors bortezomib and carfilzomib used for the treatment of multiple myeloma do not inhibit the serine protease HtrA2/Omi. Toxicol Res (Camb) 2016; 5:1619-1628. [PMID: 30090462 PMCID: PMC6062231 DOI: 10.1039/c6tx00220j] [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: 05/19/2016] [Accepted: 08/23/2016] [Indexed: 12/26/2022] Open
Abstract
The proteasome inhibitor bortezomib is associated with the development of peripheral neuropathy in patients, but the mechanism is not fully understood.
The proteasome inhibitor bortezomib is associated with the development of peripheral neuropathy in patients, but the mechanism by which bortezomib can induce peripheral neuropathy is not fully understood. One study suggested that off-target inhibition of proteases other than the proteasome, particularly HtraA2/Omi, may be the underlying mechanism of the neuropathy. The same study also concluded that carfilzomib, a second proteasome inhibitor that is associated with less peripheral neuropathy in patients than bortezomib, showed no inhibition of HtrA2/Omi. The goal of the work described here was to determine whether either proteasome inhibitors truly affected HtrA2/Omi activity. A variety of methods were used to test the effects of both bortezomib and carfilzomib on HtrA2/Omi activity that included in vitro recombinant enzyme assays, and studies with the human neuroblastoma SH-SY5Y cell line and HtrA2/Omi-knockout mouse embryonic fibroblasts. The compound ucf-101 was used to assess the effects of specific HtrA2/Omi inhibition. In contrast to previously published data, our results clearly demonstrated that neither bortezomib nor carfilzomib inhibited HtrA2/Omi activity in recombinant enzyme assays at concentrations up to 100 μM, while the specific inhibitor ucf-101 did inhibit the enzyme. The proteasome inhibitors did not inhibit HtrA2/Omi activity in either SH-SY5Y cells or mouse embryonic fibroblasts, as determined by expression of the HtrA2/Omi substrates eIF4G1 and UCH-L1. Based on our biochemical and cell-based assays, we conclude that neither bortezomib nor carfilzomib inhibited HtrA2/Omi activity. Therefore, it is unlikely that bortezomib associated peripheral neuropathy is a direct result of off-target inhibition of HtrA2/Omi.
Collapse
Affiliation(s)
- Vilmos Csizmadia
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| | - Paul Hales
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| | - Christopher Tsu
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| | - Jingya Ma
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| | - Jiejin Chen
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| | - Pooja Shah
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| | - Paul Fleming
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| | - Joseph J Senn
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| | - Vivek J Kadambi
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| | - Larry Dick
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| | - Francis S Wolenski
- Millennium Pharmaceuticals , Inc (a wholly owned subsidiary of Takeda Pharmaceutical Company Limited) , Cambridge , MA 02139 , USA . ; ; Tel: +1 617-551-3620
| |
Collapse
|
22
|
Abstract
Store-operated calcium entry (SOCE) is a pathway that moves Ca(2+) across the plasma membrane and is mediated by two major proteins, STIM1 and Orai1. Here, we discovered that the cytoplasmic domain of STIM1 is a target for calpains, a family of Ca(2+)-activated proteases. We found that calpain cleavage of STIM1 serves to control its cellular abundance and was noticeably increased under conditions of cellular stress and apoptosis. Dysregulation of STIM1 levels has been reported to have human disease consequences and our results suggest a mechanism for controlling STIM1 abundance.
Collapse
|
23
|
Ahmed RR, Mahmoud A, Ahmed OM, Metwalli A, Ebaid H. Up-regulation of Hsp72 and keratin16 mediates wound healing in streptozotocin diabetic rats. Biol Res 2015; 48:54. [PMID: 26428860 PMCID: PMC4591711 DOI: 10.1186/s40659-015-0044-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 09/17/2015] [Indexed: 01/17/2023] Open
Abstract
Background Impaired wound healing is a complication of diabetes and a serious problem in clinical practice. We previously found that whey protein (WP) was able to regulate wound healing normally in streptozotocin (STZ)-diabetic models. This subsequent study was designed to assess the effect of WP on heat shock protein-72 (Hsp72) and keratin16 (Krt16) expression during wound healing in diabetic rats. Methods WP at a dosage of 100 mg/kg of body weight was orally administered daily to wounded normal and STZ-diabetic rats for 8 days. Results At day 4, the WP-treated diabetic wound was significantly reduced compared to that in the corresponding control. Diabetic wounded rats developed severe inflammatory infiltration and moderate capillary dilatation and regeneration. Treated rats had mild necrotic formation, moderate infiltration, moderate to severe capillary dilatation and regeneration, in addition to moderate epidermal formation. Hsp72 and Krt16 densities showed low and dense activity in diabetic wounded and diabetic wounded treated groups, respectively. At day 8, WP-treatment of diabetic wounded animals revealed great amelioration with complete recovery and closure of the wound. Reactivity of Hsp72 and Krt16 was reversed, showing dense and low, or medium and low, activity in the diabetic wounded and diabetic wounded treated groups, respectively. Hsp72 expression in the pancreas was found to show dense reactivity with WP-treated diabetic wound rats. Conclusion This data provides evidence for the potential impact of WP in the up-regulation of Hsp72 and Krt16 in T1D, resulting in an improved wound healing process in diabetic models.
Collapse
Affiliation(s)
- Rasha R Ahmed
- Cell Biology and Histology Division, Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
| | - Ayman Mahmoud
- Physiology Division, Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
| | - Osama M Ahmed
- Physiology Division, Zoology Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt.
| | - Ali Metwalli
- Department of Food Science, College of Agriculture and Food Science, King Saud University, Riyadh, Saudi Arabia. .,Department of Dairy, Faculty of Agriculture, El-Minia University, El-Minia, Egypt.
| | - Hossam Ebaid
- Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, KSA. .,Department of Zoology, Faculty of Science, El-Minia University, El-Minia, Egypt.
| |
Collapse
|
24
|
Díaz-Ruiz A, Guzmán-Ruiz R, Moreno NR, García-Rios A, Delgado-Casado N, Membrives A, Túnez I, El Bekay R, Fernández-Real JM, Tovar S, Diéguez C, Tinahones FJ, Vázquez-Martínez R, López-Miranda J, Malagón MM. Proteasome Dysfunction Associated to Oxidative Stress and Proteotoxicity in Adipocytes Compromises Insulin Sensitivity in Human Obesity. Antioxid Redox Signal 2015; 23:597-612. [PMID: 25714483 PMCID: PMC4554552 DOI: 10.1089/ars.2014.5939] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
AIMS Obesity is characterized by a low-grade systemic inflammatory state and adipose tissue (AT) dysfunction, which predispose individuals to the development of insulin resistance (IR) and metabolic disease. However, a subset of obese individuals, referred to as metabolically healthy obese (MHO) individuals, are protected from obesity-associated metabolic abnormalities. Here, we aim at identifying molecular factors and pathways in adipocytes that are responsible for the progression from the insulin-sensitive to the insulin-resistant, metabolically unhealthy obese (MUHO) phenotype. RESULTS Proteomic analysis of paired samples of adipocytes from subcutaneous (SC) and omental (OM) human AT revealed that both types of cells are altered in the MUHO state. Specifically, the glutathione redox cycle and other antioxidant defense systems as well as the protein-folding machinery were dysregulated and endoplasmic reticulum stress was increased in adipocytes from IR subjects. Moreover, proteasome activity was also compromised in adipocytes of MUHO individuals, which was associated with enhanced accumulation of oxidized and ubiquitinated proteins in these cells. Proteasome activity was also impaired in adipocytes of diet-induced obese mice and in 3T3-L1 adipocytes exposed to palmitate. In line with these data, proteasome inhibition significantly impaired insulin signaling in 3T3-L1 adipocytes. INNOVATION This study provides the first evidence of the occurrence of protein homeostasis deregulation in adipocytes in human obesity, which, together with oxidative damage, interferes with insulin signaling in these cells. CONCLUSION Our results suggest that proteasomal dysfunction and impaired proteostasis in adipocytes, resulting from protein oxidation and/or misfolding, constitute major pathogenic mechanisms in the development of IR in obesity.
Collapse
Affiliation(s)
- Alberto Díaz-Ruiz
- 1 Department of Cell Biology, Physiology, and Immunology, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Reina Sofia University Hospital/University of Córdoba , Córdoba, Spain .,2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain
| | - Rocío Guzmán-Ruiz
- 1 Department of Cell Biology, Physiology, and Immunology, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Reina Sofia University Hospital/University of Córdoba , Córdoba, Spain .,2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain
| | - Natalia R Moreno
- 1 Department of Cell Biology, Physiology, and Immunology, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Reina Sofia University Hospital/University of Córdoba , Córdoba, Spain .,2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain
| | - Antonio García-Rios
- 2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain .,3 Lipids and Atherosclerosis Unit, IMIBIC/Reina Sofia University Hospital/University of Córdoba , Córdoba, Spain
| | - Nieves Delgado-Casado
- 2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain .,3 Lipids and Atherosclerosis Unit, IMIBIC/Reina Sofia University Hospital/University of Córdoba , Córdoba, Spain
| | - Antonio Membrives
- 4 Unidad de Gestión Clínica de Cirugía General y Digestivo. Sección de Obesidad, IMIBIC/Reina Sofia University Hospital , Córdoba, Spain
| | - Isaac Túnez
- 5 Department of Biochemistry and Molecular Biology, IMIBIC/Reina Sofia University Hospital/University of Córdoba , Córdoba, Spain
| | - Rajaa El Bekay
- 2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain .,6 Biomedical Research Laboratory, Endocrinology Department, Hospital Virgen de la Victoria , Málaga, Spain
| | - José M Fernández-Real
- 2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain .,7 Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomédica de Girona (IdIBGi) , Girona, Spain
| | - Sulay Tovar
- 2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain .,8 Department of Physiology, School of Medicine-CIMUS-Instituto de Investigaciones Sanitarias (IDIS), University of Santiago de Compostela , Santiago de Compostela, A Coruña, Spain
| | - Carlos Diéguez
- 2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain .,8 Department of Physiology, School of Medicine-CIMUS-Instituto de Investigaciones Sanitarias (IDIS), University of Santiago de Compostela , Santiago de Compostela, A Coruña, Spain
| | - Francisco J Tinahones
- 2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain .,6 Biomedical Research Laboratory, Endocrinology Department, Hospital Virgen de la Victoria , Málaga, Spain
| | - Rafael Vázquez-Martínez
- 1 Department of Cell Biology, Physiology, and Immunology, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Reina Sofia University Hospital/University of Córdoba , Córdoba, Spain .,2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain
| | - José López-Miranda
- 2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain .,3 Lipids and Atherosclerosis Unit, IMIBIC/Reina Sofia University Hospital/University of Córdoba , Córdoba, Spain
| | - María M Malagón
- 1 Department of Cell Biology, Physiology, and Immunology, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Reina Sofia University Hospital/University of Córdoba , Córdoba, Spain .,2 CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III , Córdoba, Spain
| |
Collapse
|
25
|
Chao TH, Chang MY, Su SJ, Su SH. Inducible nitric oxide synthase mediates MG132 lethality in leukemic cells through mitochondrial depolarization. Free Radic Biol Med 2014; 74:175-87. [PMID: 24909615 DOI: 10.1016/j.freeradbiomed.2014.05.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 04/28/2014] [Accepted: 05/29/2014] [Indexed: 11/29/2022]
Abstract
Proteasomes are highly expressed in rapidly growing neoplastic cells and essential for controlling the cell cycle process and mitochondrial homeostasis. Pharmacological inhibition of the proteasome shows a significant anticancer effect on hematopoietic malignancies that is usually associated with the generation of reactive oxygen species. In this study, we comprehensively investigated the role of endogenous oxidants in various cellular events of K562 leukemic cells in response to treatment with MG132, a proteasome inhibitor. MG132 at 1.4 µM potently triggered G2/M arrest, mitochondrial depolarization, and apoptosis. By such treatment, the protein level of inducible nitric oxide synthase (iNOS) was doubled and cellular oxidants, including nitric oxide, superoxide, and their derivatives, were increasingly produced. In MG132-treated cells, the increase in iNOS-derived oxidants was responsible for mitochondrial depolarization and caspase-dependent apoptosis, but was insignificant in G2/M arrest. The amount of iNOS was negatively correlated with that of manganese superoxide dismutase (MnSOD). Whereas iNOS activity was inhibited by aminoguanidine, cellular MnSOD levels as well as mitochondrial membrane potentials were upregulated, and consequentially G2/M arrest and apoptosis were thoroughly reversed. It is suggested that cells rich in functional mitochondria possess improved proteasome activity, which antagonizes the cytotoxic and cytostatic effects of MG132. In contrast to iNOS, endothelial NOS-driven cGMP-dependent signaling promoted mitochondrial function and survival of MG132-stressed cells. In conclusion, the functional interplay of proteasomes and mitochondria is crucial for leukemic cell growth, wherein iNOS plays a key role.
Collapse
Affiliation(s)
- Tung Hui Chao
- Institute of Medical Sciences, College of Medicine, Tzu-Chi University, Hualien 97004, Taiwan
| | - Meng-Ya Chang
- Institute of Medical Sciences, College of Medicine, Tzu-Chi University, Hualien 97004, Taiwan; Department of Medical Research, Buddhist Tzu-Chi General Hospital, Hualien, Taiwan
| | - Shu-Jem Su
- Department of Medical Laboratory Science and Biotechnology, School of Medicine and Health Sciences, FooYin University, Kaohsiung, Taiwan
| | - Shu-Hui Su
- Institute of Medical Sciences, College of Medicine, Tzu-Chi University, Hualien 97004, Taiwan; Department of Molecular Biology and Human Genetics, College of Life Sciences, Tzu-Chi University, Hualien 97004, Taiwan; Department of Laboratory Medicine and Biotechnology, College of Medicine, Tzu-Chi University, Hualien 97004, Taiwan.
| |
Collapse
|
26
|
Timani KA, Liu Y, Suvannasankha A, He JJ. Regulation of ubiquitin-proteasome system-mediated Tip110 protein degradation by USP15. Int J Biochem Cell Biol 2014; 54:10-9. [PMID: 24984263 DOI: 10.1016/j.biocel.2014.06.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 06/16/2014] [Accepted: 06/19/2014] [Indexed: 10/25/2022]
Abstract
Tip110 is a nuclear protein and has been shown to function in tumor antigenicity, regulation of gene transcription, pre-mRNA splicing, stem cell proliferation and differentiation, and embryonic development. To characterize the in vivo functions of Tip110, a transgene cassette expressing human Tip110 protein (hTip110) was used to generate hTip110 transgenic (Tg) mice. Unexpectedly, only Tip110 mRNA but not Tip110 protein was expressed in Tg MEF and tissues. Treatment of Tg MEF with proteasome inhibitors led to detection of hTip110 protein, which prompted us to investigate the regulatory mechanisms of Tip110 degradation in mouse cells. We found that hTip110 was more sensitive to ubiquitin-proteasome system (UPS)-mediated protein degradation than mouse Tip110 (mTip110), likely resulting from more hTip110 ubiquitination. Using affinity chromatography and proteomics, we identified USP15, a deubiquitinating enzyme, to be associated with Tip110. Tip110 expression led to re-distribution of USP15 from the cytoplasm to the nucleus and complete co-localization of Tip110 with USP15 in the nucleus, whereas USP15 expression resulted in hTip110 deubiquitination. Interestingly, USP15 knockdown restored hTip110 protein expression in Tg MEF and USP15 expression had little effects. Taken together, these results provide insights into the regulatory mechanism of human Tip110 degradation by USP15.
Collapse
Affiliation(s)
- Khalid Amine Timani
- Department of Cell Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA.
| | - Ying Liu
- Department of Cell Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA
| | - Attaya Suvannasankha
- Division of Hematology and Oncology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Johnny J He
- Department of Cell Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA
| |
Collapse
|
27
|
Ingemann L, Kirkegaard T. Lysosomal storage diseases and the heat shock response: convergences and therapeutic opportunities. J Lipid Res 2014; 55:2198-210. [PMID: 24837749 DOI: 10.1194/jlr.r048090] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Lysosomes play a vital role in the maintenance of cellular homeostasis through the recycling of cell constituents, a key metabolic function which is highly dependent on the correct function of the lysosomal hydrolases and membrane proteins, as well as correct membrane lipid stoichiometry and composition. The critical role of lysosomal functionality is evident from the severity of the diseases in which the primary lesion is a genetically defined loss-of-function of lysosomal hydrolases or membrane proteins. This group of diseases, known as lysosomal storage diseases (LSDs), number more than 50 and are associated with severe neurodegeneration, systemic disease, and early death, with only a handful of the diseases having a therapeutic option. Another key homeostatic system is the metabolic stress response or heat shock response (HSR), which is induced in response to a number of physiological and pathological stresses, such as protein misfolding and aggregation, endoplasmic reticulum stress, oxidative stress, nutrient deprivation, elevated temperature, viral infections, and various acute traumas. Importantly, the HSR and its cardinal members of the heat shock protein 70 family has been shown to protect against a number of degenerative diseases, including severe diseases of the nervous system. The cytoprotective actions of the HSR also include processes involving the lysosomal system, such as cell death, autophagy, and protection against lysosomal membrane permeabilization, and have shown promise in a number of LSDs. This review seeks to describe the emerging understanding of the interplay between these two essential metabolic systems, the lysosomes and the HSR, with a particular focus on their potential as a therapeutic target for LSDs.
Collapse
|
28
|
Jia B, Wu Y, Zhou Y. 14-3-3 and aggresome formation: implications in neurodegenerative diseases. Prion 2014; 8:28123. [PMID: 24549097 DOI: 10.4161/pri.28123] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Protein misfolding and aggregation underlie the pathogenesis of many neurodegenerative diseases. In addition to chaperone-mediated refolding and proteasomal degradation, the aggresome-macroautophagy pathway has emerged as another defense mechanism for sequestration and clearance of toxic protein aggregates in cells. Previously, the 14-3-3 proteins were shown to be indispensable for the formation of aggresomes induced by mutant huntingtin proteins. In a recent study, we have determined that 14-3-3 functions as a molecular adaptor to recruit chaperone-associated misfolded proteins to dynein motors for transport to aggresomes. This molecular complex involves a dimeric binding of 14-3-3 to both the dynein-intermediate chain (DIC) and an Hsp70 co-chaperone Bcl-2-associated athanogene 3 (BAG3). As 14-3-3 has been implicated in various neurodegenerative diseases, our findings may provide mechanistic insights into its role in managing misfolded protein stress during the process of neurodegeneration.
Collapse
Affiliation(s)
- Baohui Jia
- Department of Biomedical Sciences; Florida State University College of Medicine; Tallahassee, FL USA; Guang An Men Hospital; Beijing PR China
| | - Yuying Wu
- Department of Biomedical Sciences; Florida State University College of Medicine; Tallahassee, FL USA
| | - Yi Zhou
- Department of Biomedical Sciences; Florida State University College of Medicine; Tallahassee, FL USA
| |
Collapse
|
29
|
Enomoto A, Fukasawa T, Takamatsu N, Ito M, Morita A, Hosoi Y, Miyagawa K. The HSP90 inhibitor 17-allylamino-17-demethoxygeldanamycin modulates radiosensitivity by downregulating serine/threonine kinase 38 via Sp1 inhibition. Eur J Cancer 2013; 49:3547-58. [DOI: 10.1016/j.ejca.2013.06.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 05/18/2013] [Accepted: 06/26/2013] [Indexed: 12/19/2022]
|
30
|
Magill L, Walker B, Irvine AE. The Proteasome: A Novel Therapeutic Target in Haematopoietic Malignancy. Hematology 2013; 8:275-83. [PMID: 14530169 DOI: 10.1080/10245330310001604755] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The proteasome plays a key role in regulating protein degradation in eukaryotic cells. A range of synthetic inhibitors of proteasome activity have been developed which have helped elucidate its role in the cell. These inhibitors have selectively induced apoptosis in malignant cells in vitro suggesting that the proteasome may be a novel therapeutic target. First generation proteasome inhibitors are currently showing promise in phase II/III clinical trials for patients with multiple myeloma.
Collapse
Affiliation(s)
- Laura Magill
- Department of Haemotology, Queen's University of Belfast, UK
| | | | | |
Collapse
|
31
|
Welc SS, Judge AR, Clanton TL. Skeletal muscle interleukin-6 regulation in hyperthermia. Am J Physiol Cell Physiol 2013; 305:C406-13. [DOI: 10.1152/ajpcell.00084.2013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously reported that IL-6 production is acutely elevated in skeletal muscles exposed to ≥41°C, but the regulatory pathways are poorly understood. The present study characterizes the heat-induced transcriptional control of IL-6 in C2C12 muscle fibers. Hyperthermia exposure (42°C for 1 h) induced transcription from an IL-6 promoter-luciferase reporter plasmid. Heat shock factor-1 (HSF-1), a principal mediator of the heat shock response, was then tested for its role in IL-6 regulation. Overexpression of a constitutively active HSF-1 construct increased basal (37°C) promoter activity, whereas overexpression of a dominant negative HSF-1 reduced IL-6 promoter activity during basal and hyperthermia conditions. Since hyperthermia also induces stress-activated protein kinase (SAPK) signaling, we tested whether mutation of a transcription site downstream of SAPK, (i.e., activator protein-1, AP-1) influences IL-6 transcription in hyperthermia. The mutation had no effect on baseline reporter activity but completely inhibited heat-induced activity. We then tested whether pharmacologically induced states of protein stress, characteristic of cellular responses to hyperthermia and known to induce SAPKs and HSF-1, would induce IL-6 production in the absence of heat. The proteasome was inhibited with MG-132 in one set of experiments, and the unfolded protein response was stimulated with dithiothreitol, thapsigargin, tunicamycin, or castanospermine in other experiments. All treatments stimulated IL-6 protein secretion in the absence of hyperthermia. These studies demonstrate that IL-6 regulation in hyperthermia is directly controlled by HSF-1 and AP-1 signaling and that the IL-6 response in C2C12 myotubes is sensitive to categories of protein stress that reflect accumulation of damaged or unfolded proteins.
Collapse
Affiliation(s)
- Steven S. Welc
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida; and
| | - Andrew R. Judge
- Department of Physical Therapy, College of Health and Health Professions, University of Florida, Gainesville, Florida
| | - Thomas L. Clanton
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, Florida; and
| |
Collapse
|
32
|
The combination of silencing BAG3 and inhibition of the JNK pathway enhances hyperthermia sensitivity in human oral squamous cell carcinoma cells. Cancer Lett 2013; 335:52-7. [DOI: 10.1016/j.canlet.2013.01.049] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 01/29/2013] [Accepted: 01/29/2013] [Indexed: 11/17/2022]
|
33
|
Cunha D, Cunha R, Côrte-Real M, Chaves SR. Cisplatin-induced cell death in Saccharomyces cerevisiae is programmed and rescued by proteasome inhibition. DNA Repair (Amst) 2013; 12:444-9. [DOI: 10.1016/j.dnarep.2013.02.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/17/2013] [Accepted: 02/17/2013] [Indexed: 11/26/2022]
|
34
|
Uchida N, Hsieh MM, Washington KN, Tisdale JF. Efficient transduction of human hematopoietic repopulating cells with a chimeric HIV1-based vector including SIV capsid. Exp Hematol 2013; 41:779-788.e1. [PMID: 23665451 DOI: 10.1016/j.exphem.2013.04.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 03/05/2013] [Accepted: 04/03/2013] [Indexed: 11/19/2022]
Abstract
Innate immune factors, such as TRIM5α and cyclophilin A (CypA), act as a major restriction factor of retroviral infection among species. When HIV1 infects human cells, HIV1 capsid binds to human CypA to escape from human TRIM5α restriction. However, in rhesus cells, the mismatch between HIV1 capsid and rhesus CypA is recognized by rhesus TRIM5α to reduce HIV1 infectivity through proteasomal degradation. To circumvent this block, we previously developed a chimeric HIV1 vector (χHIV) that substituted HIV1 capsid with SIV capsid, and it significantly increased transduction efficiency for nonhuman primate cells. In this study, we evaluated whether the χHIV vector efficiently transduces human cells, and the transduction efficiency might increase by a CypA inhibitor (cyclosporine) and a proteasome inhibitor (MG132). The χHIV vector could transduce human CD34⁺ cells, as efficiently as the HIV1 vector, in vitro and in xenograft mice, even in the mismatch between SIV capsid and human CypA. Cyclosporine decreased transduction efficiency with the HIV1 vector, whereas it slightly increased transduction efficiency with the χHIV vector in human CD34⁺ cells. MG132 increased transduction efficiency with both χHIV and HIV1 vectors in the same manner. However, MG132 was toxic to human CD34⁺ cells at high concentrations, and both drugs had a small range of effective dosage. These findings demonstrate that both χHIV and HIV1 vectors have similar transduction efficiency for human hematopoietic repopulating cells, suggesting that the χHIV vector escapes from TRIM5α restriction, which is independent of human CypA.
Collapse
Affiliation(s)
- Naoya Uchida
- Molecular and Clinical Hematology Branch, National Heart Lung and Blood Institute-National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | | | | | | |
Collapse
|
35
|
Pietkiewicz S, Sohn D, Piekorz RP, Grether-Beck S, Budach W, Sabapathy K, Jänicke RU. Oppositional regulation of Noxa by JNK1 and JNK2 during apoptosis induced by proteasomal inhibitors. PLoS One 2013; 8:e61438. [PMID: 23593480 PMCID: PMC3623862 DOI: 10.1371/journal.pone.0061438] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 03/14/2013] [Indexed: 01/28/2023] Open
Abstract
Proteasome inhibitors (PIs) potently induce apoptosis in a variety of tumor cells, but the underlying mechanisms are not fully elucidated. Comparing PI-induced apoptosis susceptibilities of various mouse embryonic fibroblast (MEF) lines differing in their c-jun N-terminal kinase (JNK) 1 and 2 status, we show that several hallmarks of apoptosis were most rapidly detectable in JNK2-/- cells, whereas they appeared only delayed and severely reduced in their intensities in cells expressing JNK2. Consistent with our finding that PI-induced apoptosis requires de novo protein synthesis, the proteasomal inhibitor MG-132 induced expression of the BH3-only protein Noxa at the transcriptional level in a JNK1-dependent, but JNK2-opposing manner. As the knockdown of Noxa blocked only the rapid PI-induced apoptosis of JNK2-/- cells, but not the delayed death occurring in JNK1-/- and JNK1+/+ cells, our data uncover a novel PI-induced apoptosis pathway that is regulated by the JNK1/2-dependent expression of Noxa. Furthermore, several transcription factors known to modulate Noxa expression including ATF3, ATF4, c-Jun, c-Myc, HIF1α, and p53 were found upregulated following MG-132 exposure. From those, only knockdown of c-Myc rescued JNK2-/- cells from PI-induced apoptosis, however, without affecting expression of Noxa. Together, our data not only show that a rapid execution of PI-induced apoptosis requires JNK1 for upregulation of Noxa via an as yet unknown transcription factor, but also that JNK2 controls this event in an oppositional manner.
Collapse
Affiliation(s)
- Sabine Pietkiewicz
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, University of Düsseldorf, Düsseldorf, Germany
| | - Dennis Sohn
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, University of Düsseldorf, Düsseldorf, Germany
| | - Roland P. Piekorz
- Institute for Biochemistry and Molecular Biology II, University of Düsseldorf, Düsseldorf, Germany
| | | | - Wilfried Budach
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, University of Düsseldorf, Düsseldorf, Germany
| | - Kanaga Sabapathy
- Division of Cellular & Molecular Research, Humphrey Oei Institute of Cancer Research, National Cancer Centre, Singapore, Singapore
| | - Reiner U. Jänicke
- Laboratory of Molecular Radiooncology, Clinic and Policlinic for Radiation Therapy and Radiooncology, University of Düsseldorf, Düsseldorf, Germany
- * E-mail:
| |
Collapse
|
36
|
Mathema VB, Manzoor Z, Koo JE, Koh YS. Inhibition of cell death of bone marrow-derived macrophages infected with Ehrlichia muris. Ticks Tick Borne Dis 2013; 4:185-90. [PMID: 23352172 DOI: 10.1016/j.ttbdis.2012.11.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 11/14/2012] [Accepted: 11/14/2012] [Indexed: 01/12/2023]
Abstract
Ehrlichia muris is a Gram-negative obligate intracellular bacterium belonging to the family Anaplasmataceae. It preferentially replicates inside macrophages by utilizing nutrients and processes of the host cell. In the present article, we studied the effects of E. muris infection on cell death of bone marrow-derived macrophages (BMDMs). Primary BMDMs were used for accessing E. muris-induced cell death, pro-inflammatory cytokine production and Western blot analysis. Human embryonic kidney cell line 293T (HEK293T) was used to access nuclear factor-kappaB (NF-κB) activity. BMDMs infected with E. muris showed significant inhibition of cell death when compared to uninfected cells. E. muris infection resulted in IκBα degradation, thus activation of NF-κB. In NF-κB reporter gene assay, the HEK293T cells infected with E. muris exhibited robust NF-κB-dependent luciferase activity in a bacterial dose-dependent manner. Furthermore, E. muris-induced inhibition of BMDMs cell death was abolished in the presence of MG132, a proteasome inhibitor that blocks NF-κB activation. Taken together, the results suggest that E. muris infection of BMDMs may have an inhibitory effect on cell death via a mechanism dependent on NF-κB activation.
Collapse
|
37
|
Stein ML, Groll M. Applied techniques for mining natural proteasome inhibitors. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:26-38. [PMID: 23360979 DOI: 10.1016/j.bbamcr.2013.01.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 01/14/2013] [Indexed: 11/17/2022]
Abstract
In eukaryotic cells, the ubiquitin-proteasome-system (UPS) is responsible for the non-lysosomal degradation of proteins and plays a pivotal role in such vital processes as protein homeostasis, antigen processing or cell proliferation. Therefore, it is an attractive drug target with various applications in cancer and immunosuppressive therapies. Being an evolutionary well conserved pathway, many pathogenic bacteria have developed small molecules, which modulate the activity of their hosts' UPS components. Such natural products are, due to their stepwise optimization over the millennia, highly potent in terms of their binding mechanisms, their bioavailability and selectivity. Generally, this makes bioactive natural products an ideal starting point for the development of novel drugs. Since four out of the ten best seller drugs are natural product derivatives, research in this field is still of unfathomable value for the pharmaceutical industry. The currently most prominent example for the successful exploitation of a natural compound in the UPS field is carfilzomib (Kyprolis®), which represents the second FDA approved drug targeting the proteasome after the admission of the blockbuster bortezomib (Velcade®) in 2003. On the other hand side of the spectrum, ONX 0914, which is derived from the same natural product as carfilzomib, has been shown to selectively inhibit the immune response related branch of the pathway. To date, there exists a huge potential of UPS inhibitors with regard to many diseases. Both approved drugs against the proteasome show severe side effects, adaptive resistances and limited applicability, thus the development of novel compounds with enhanced properties is a main objective of active research. In this review, we describe the techniques, which can be utilized for the discovery of novel natural inhibitors, which in particular block the 20S proteasomal activity. In addition, we will illustrate the successful implementation of a recently published methodology with the example of a highly potent but so far unexploited group of proteasome inhibitors, the syrbactins, and their biological functions. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.
Collapse
Affiliation(s)
- Martin L Stein
- Center for Integrated Protein Science at the Department Chemie, Lehrstuhl für Biochemie, Technische Unversität München, Lichtenbergstraße 4, 85748 Garching, Germany.
| | | |
Collapse
|
38
|
Rastogi N, Mishra DP. Therapeutic targeting of cancer cell cycle using proteasome inhibitors. Cell Div 2012; 7:26. [PMID: 23268747 PMCID: PMC3584802 DOI: 10.1186/1747-1028-7-26] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 11/15/2012] [Indexed: 12/21/2022] Open
Abstract
Proteasomes are multicatalytic protease complexes in the cell, involved in the non-lysosomal recycling of intra-cellular proteins. Proteasomes play a critical role in regulation of cell division in both normal as well as cancer cells. In cancer cells this homeostatic function is deregulated leading to the hyperactivation of the proteasomes. Proteasome inhibitors (PIs) are a class of compounds, which either reversibly or irreversibly block the activity of proteasomes and induce cancer cell death. Interference of PIs with the ubiquitin proteasome pathway (UPP) involved in protein turnover in the cell leads to the accumulation of proteins engaged in cell cycle progression, which ultimately put a halt to cancer cell division and induce apoptosis. Upregulation of many tumor suppressor proteins involved in cell cycle arrest are known to play a role in PI induced cell cycle arrest in a variety of cancer cells. Although many PIs target the proteasomes, not all of them are effective in cancer therapy. Some cancers develop resistance against proteasome inhibition by possibly activating compensatory signaling pathways. However, the details of the activation of these pathways and their contribution to resistance to PI therapy remain obscure. Delineation of these pathways may help in checking resistance against PIs and deducing effective combinational approaches for improved treatment strategies. This review will discuss some of the signaling pathways related to proteasome inhibition and cell division that may help explain the basis of resistance of some cancers to proteasome inhibitors and underline the need for usage of PIs in combination with traditional chemotherapy.
Collapse
Affiliation(s)
- Namrata Rastogi
- Cell Death Research Laboratory, Division of Endocrinology, CSIR- Central Drug Research Institute, Lucknow, 226001, India.
| | | |
Collapse
|
39
|
Induction of heat shock protein 70 (Hsp70) prevents neuregulin-induced demyelination by enhancing the proteasomal clearance of c-Jun. ASN Neuro 2012; 4:e00102. [PMID: 23240583 PMCID: PMC3517131 DOI: 10.1042/20120047] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Modulating molecular chaperones is emerging as an attractive approach to treat neurodegenerative diseases associated with protein aggregation, DPN (diabetic peripheral neuropathy) and possibly, demyelinating neuropathies. KU-32 [N-(7-((2R,3R,4S,5R)-3,4-dihydroxy-5-methoxy-6,6-dimethyl-tetrahydro-2H-pyran-2-yloxy)-8-methyl-2-oxo-2H-chromen-3-yl)acetamide] is a small molecule inhibitor of Hsp90 (heat shock protein 90) and reverses sensory deficits associated with myelinated fibre dysfunction in DPN. Additionally, KU-32 prevented the loss of myelinated internodes induced by treating myelinated SC (Schwann cell)-DRG (dorsal root ganglia) sensory neuron co-cultures with NRG1 (neuregulin-1 Type 1). Since KU-32 decreased NRG1-induced demyelination in an Hsp70-dependent manner, the goal of the current study was to clarify how Hsp70 may be mechanistically linked to preventing demyelination. The activation of p42/p44 MAPK (mitogen-activated protein kinase) and induction of the transcription factor c-Jun serve as negative regulators of myelination. NRG1 activated MAPK, induced c-Jun expression and promoted a loss of myelin segments in DRG explants isolated from both WT (wild-type) and Hsp70 KO (knockout) mice. Although KU-32 did not block the activation of MAPK, it blocked c-Jun induction and protected against a loss of myelinated segments in WT mice. In contrast, KU-32 did not prevent the NRG1-dependent induction of c-Jun and loss of myelin segments in explants from Hsp70 KO mice. Overexpression of Hsp70 in myelinated DRG explants prepared from WT or Hsp70 KO mice was sufficient to block the induction of c-Jun and the loss of myelin segments induced by NRG1. Lastly, inhibiting the proteasome prevented KU-32 from decreasing c-Jun levels. Collectively, these data support that Hsp70 induction is sufficient to prevent NRG1-induced demyelination by enhancing the proteasomal degradation of c-Jun.
Collapse
|
40
|
Zhou J, Zhang S, Xue J, Avery J, Wu J, Lind SE, Ding WQ. Activation of peroxisome proliferator-activated receptor α (PPARα) suppresses hypoxia-inducible factor-1α (HIF-1α) signaling in cancer cells. J Biol Chem 2012; 287:35161-35169. [PMID: 22932900 DOI: 10.1074/jbc.m112.367367] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of peroxisome proliferator-activated receptor α (PPARα) has been demonstrated to inhibit tumor growth and angiogenesis, yet the mechanisms behind these actions remain to be characterized. In this study, we examined the effects of PPARα activation on the hypoxia-inducible factor-1α (HIF-1α) signaling pathway in human breast (MCF-7) and ovarian (A2780) cancer cells under hypoxia. Incubation of cancer cells under 1% oxygen for 16 h significantly induced HIF-1α expression and activity as assayed by Western blotting and reporter gene analysis. Treatment of the cells with PPARα agonists, but not a PPARγ agonist, prior to hypoxia diminished hypoxia-induced HIF-1α expression and activity, and addition of a PPARα antagonist attenuated the suppression of HIF-1α signaling. Activation of PPARα attenuated hypoxia-induced HA-tagged HIF-1α protein expression without affecting the HA-tagged HIF-1α mutant protein level, indicating that PPARα activation promotes HIF-1α degradation in these cells. This was further confirmed using proteasome inhibitors, which reversed PPARα-mediated suppression of HIF-1α expression under hypoxia. Using the co-immunoprecipitation technique, we found that activation of PPARα enhances the binding of HIF-1α to von Hippel-Lindau tumor suppressor (pVHL), a protein known to mediate HIF-1α degradation through the ubiquitin-proteasome pathway. Following PPARα-mediated suppression of HIF-1α signaling, VEGF secretion from the cancer cells was significantly reduced, and tube formation by endothelial cells was dramatically impaired. Taken together, these findings demonstrate for the first time that activation of PPARα suppresses hypoxia-induced HIF-1α signaling in cancer cells, providing novel insight into the anticancer properties of PPARα agonists.
Collapse
Affiliation(s)
- Jundong Zhou
- Department of Radio-Oncology, Nanjing Medical University Affiliated Suzhou Hospital; Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Shuyu Zhang
- School of Radiation Medicine and Protection, Soochow University, Suzhou 205123, China; Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Jing Xue
- Department of Radio-Oncology, Nanjing Medical University Affiliated Suzhou Hospital; Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Jori Avery
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Jinchang Wu
- Department of Radio-Oncology, Nanjing Medical University Affiliated Suzhou Hospital
| | - Stuart E Lind
- Department of Pathology and Medicine, University of Colorado Denver, Denver, Colorado 80217
| | - Wei-Qun Ding
- Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104.
| |
Collapse
|
41
|
Parra E. Inhibition of JNK-1 by small interfering RNA induces apoptotic signaling in PC-3 prostate cancer cells. Int J Mol Med 2012; 30:923-30. [PMID: 22766602 DOI: 10.3892/ijmm.2012.1055] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 04/26/2012] [Indexed: 11/05/2022] Open
Abstract
Previous studies have shown that c-Jun-N-terminal kinase-1 (JNK-1) is involved in the transformation of primary fibroblasts and plays a role in tumor cell growth. A number of observations suggest that JNK-1 is a growth promoting factor in prostate cancer cells and blocking its function may induce apoptosis. To test this further, we used a small interfering RNA (siRNA) against JNK-1 mRNA that efficiently inhibits JNK-1 expression in the prostate cancer cell line, PC-3. The application of siRNA against JNK-1 decreased the expression of JNK-1 and affected the expression of p21, XIAP and Bcl-2, but had no effect on the expression of VEGF. In contrast, a control scramble siRNA did not affect the expression of the above indicated proteins. The downregulation of JNK-1 expression at both the mRNA and protein levels was detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. Cell proliferation inhibition rates were determined by the MTT assay. The effect of JNK-1-siRNA on cell cycle distribution and cell apoptosis was determined by flow cytometry, DNA fragmentation and caspase activity. Our data showed that siRNA against JNK-1 mRNA, could efficiently suppress the expression of JNK-1 in PC-3 cells. After 5 days of transfection, the cell death rate was 52%, the apoptotic rate 26% and the viability rate 22%. In conclusion, downregulation of JNK-1 expression by siRNA against JNK-1 mRNA induces apoptotic signaling in prostate cancer PC-3 cells. The use of siRNA against JNK-1 as a novel approach to cancer therapy deserves further investigation.
Collapse
Affiliation(s)
- Eduardo Parra
- Biomedical Experimental Laboratory, Faculty of Sciences, University of Tarapaca, Arica, Chile.
| |
Collapse
|
42
|
Meriin AB, Zaarur N, Sherman MY. Association of translation factor eEF1A with defective ribosomal products generates a signal for aggresome formation. J Cell Sci 2012; 125:2665-74. [PMID: 22357952 DOI: 10.1242/jcs.098954] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aggresome formation is initiated upon proteasome failure, and facilitates autophagic clearance of protein aggregates to protect cells from proteotoxicity. Here we demonstrate that proteasome inhibition generates a signaling event to trigger aggresome formation. In aggresome signaling, the cell senses a build-up of aberrant newly synthesized proteins. The translation elongation factor eEF1A associated with these species, and knockdown of this factor suppressed aggresome formation. We used the Legionella toxin SidI to distinguish between the function of eEF1A in translation and its novel function in the aggresome formation. In fact, although it strongly inhibited translation, this toxin had only a marginal effect on aggresome formation. Furthermore, SidI reduced the threshold of the aberrant ribosomal products for triggering aggresome formation. Therefore, eEF1A binds defective polypeptides released from ribosomes, which generates a signal that triggers aggresome formation.
Collapse
Affiliation(s)
- Anatoli B Meriin
- Department of Biochemistry, Boston University Medical School, Boston, MA 02118, USA
| | | | | |
Collapse
|
43
|
Bouquet F, Ousset M, Biard D, Fallone F, Dauvillier S, Frit P, Salles B, Muller C. A DNA-dependent stress response involving DNA-PK occurs in hypoxic cells and contributes to cellular adaptation to hypoxia. J Cell Sci 2011; 124:1943-51. [PMID: 21576354 DOI: 10.1242/jcs.078030] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
DNA-dependent protein kinase (DNA-PK) is involved in DNA double-strand break (DSB) signalling and repair. We report that DNA-PK is activated by mild hypoxia conditions (0.1-1% O₂) as shown by (1) its autophosphorylation on Ser2056, and (2) its mobilisation from a soluble nucleoplasmic compartment to a less extractable nuclear fraction. The recruitment of DNA-PK was not followed by activation and recruitment of the XRCC4-DNA-ligase-IV complex, suggesting that DSBs are not responsible for activation of DNA-PK. To unravel the mechanism of DNA-PK activation, we show that exposure of cells to trichostatin A, a histone deacetylase inhibitor, leads to DNA-PK autophosphorylation and relocalisation to DNA. Histone acetylation (mainly H3K14) is increased in hypoxic cells and treatment with anacardic acid, an inhibitor of histone acetyl transferase, prevented both histone modifications and DNA-PK activation in hypoxic conditions. Importantly, in using either silenced DNA-PK cells or cells exposed to a specific DNA-PK inhibitor (NU7026), we demonstrated that hypoxic DNA-PK activation positively regulates the key transcription factor HIF-1 and one subsequent target gene, GLUT1. Our results show that hypoxia initiates chromatin modification and consequently DNA-PK activation, which positively regulate cellular oxygen-sensing and oxygen-signalling pathways.
Collapse
Affiliation(s)
- Fanny Bouquet
- CNRS-IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077 Toulouse, France
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Potts BC, Albitar MX, Anderson KC, Baritaki S, Berkers C, Bonavida B, Chandra J, Chauhan D, Cusack JC, Fenical W, Ghobrial IM, Groll M, Jensen PR, Lam KS, Lloyd GK, McBride W, McConkey DJ, Miller CP, Neuteboom STC, Oki Y, Ovaa H, Pajonk F, Richardson PG, Roccaro AM, Sloss CM, Spear MA, Valashi E, Younes A, Palladino MA. Marizomib, a proteasome inhibitor for all seasons: preclinical profile and a framework for clinical trials. Curr Cancer Drug Targets 2011; 11:254-84. [PMID: 21247382 DOI: 10.2174/156800911794519716] [Citation(s) in RCA: 159] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 01/11/2011] [Indexed: 12/19/2022]
Abstract
The proteasome has emerged as an important clinically relevant target for the treatment of hematologic malignancies. Since the Food and Drug Administration approved the first-in-class proteasome inhibitor bortezomib (Velcade) for the treatment of relapsed/refractory multiple myeloma (MM) and mantle cell lymphoma, it has become clear that new inhibitors are needed that have a better therapeutic ratio, can overcome inherent and acquired bortezomib resistance and exhibit broader anti-cancer activities. Marizomib (NPI-0052; salinosporamide A) is a structurally and pharmacologically unique β-lactone-γ-lactam proteasome inhibitor that may fulfill these unmet needs. The potent and sustained inhibition of all three proteolytic activities of the proteasome by marizomib has inspired extensive preclinical evaluation in a variety of hematologic and solid tumor models, where it is efficacious as a single agent and in combination with biologics, chemotherapeutics and targeted therapeutic agents. Specifically, marizomib has been evaluated in models for multiple myeloma, mantle cell lymphoma, Waldenstrom's macroglobulinemia, chronic and acute lymphocytic leukemia, as well as glioma, colorectal and pancreatic cancer models, and has exhibited synergistic activities in tumor models in combination with bortezomib, the immunomodulatory agent lenalidomide (Revlimid), and various histone deacetylase inhibitors. These and other studies provided the framework for ongoing clinical trials in patients with MM, lymphomas, leukemias and solid tumors, including those who have failed bortezomib treatment, as well as in patients with diagnoses where other proteasome inhibitors have not demonstrated significant efficacy. This review captures the remarkable translational studies and contributions from many collaborators that have advanced marizomib from seabed to bench to bedside.
Collapse
Affiliation(s)
- B C Potts
- Nereus Pharmaceuticals, Inc., 10480 Wateridge Circle, San Diego, CA 92121, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Jantas D, Lorenc-Koci E, Kubera M, Lason W. Neuroprotective effects of MAPK/ERK1/2 and calpain inhibitors on lactacystin-induced cell damage in primary cortical neurons. Neurotoxicology 2011; 32:845-56. [PMID: 21683092 DOI: 10.1016/j.neuro.2011.05.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 05/17/2011] [Accepted: 05/25/2011] [Indexed: 10/25/2022]
Abstract
The dysfunction of the proteasome system is implicated in the pathomechanism of several chronic neurodegenerative diseases. Lactacystin (LC), an irreversible proteasome inhibitor, induces cell death in primary cortical neurons, however, the molecular mechanisms of its neurotoxic action has been only partially unraveled. In this study we aimed to elucidate an involvement of the key enzymatic pathways responsible for LC-induced neuronal cell death. Incubation of primary cortical neurons with LC (0.25-50 μg/ml) evoked neuronal cell death in concentration- and time-dependent manner. Lactacystin (2.5 μg/ml; 6.6μM) enhanced caspase-3 activity, but caspase-3 inhibitor, Ac-DEVD-CHO did not attenuate the LC-evoked cell damage. Western blot analysis showed a time-dependent, prolonged activation of MAPK/ERK1/2 pathway after LC exposure. Moreover, inhibitors of MAPK/ERK1/2 signaling, U0126 and PD98052 attenuated the LC-evoked cell death. We also found that LC-treatment resulted in the induction of calpains and calpain inhibitors (MDL28170 and calpeptin) protected neurons against the LC-induced cell damage. Neuroprotective action of MAPK/ERK1/2 and calpain inhibitors were connected with attenuation of LC-induced DNA fragmentation measured by Hoechst 33342 staining and TUNEL assay. However, only MAPK/ERK1/2 but not calpain inhibitors, attenuated the LC-induced AIF (apoptosis inducing factor) release. Further studies showed no synergy between neuroprotective effects of MAPK/ERK1/2 and calpain inhibitors given in combination when compared to their effects alone. The obtained data provided evidence for neuroprotective potency of MAPK/ERK1/2 and calpain, but not caspase-3 inhibition against the neurotoxic effects of LC in primary cortical neurons and give rationale for using these inhibitors in the treatment of neurodegenerative diseases connected with proteasome dysfunction.
Collapse
Affiliation(s)
- D Jantas
- Department of Experimental Neuroendocrinology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, PL 31-343 Krakow, Poland.
| | | | | | | |
Collapse
|
46
|
p21(WAF1/CIP1) upregulation through the stress granule-associated protein CUGBP1 confers resistance to bortezomib-mediated apoptosis. PLoS One 2011; 6:e20254. [PMID: 21637851 PMCID: PMC3102688 DOI: 10.1371/journal.pone.0020254] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 04/28/2011] [Indexed: 12/24/2022] Open
Abstract
Background p21WAF1/CIP1 is a well known cyclin-dependent kinase inhibitor induced by various stress stimuli. Depending on the stress applied, p21 upregulation can either promote apoptosis or prevent against apoptotic injury. The stress-mediated induction of p21 involves not only its transcriptional activation but also its posttranscriptional regulation, mainly through stabilization of p21 mRNA levels. We have previously reported that the proteasome inhibitor MG132 induces the stabilization of p21 mRNA, which correlates with the formation of cytoplasmic RNA stress granules. The mechanism underlying p21 mRNA stabilization, however, remains unknown. Methodology/Principal Findings We identified the stress granules component CUGBP1 as a factor required for p21 mRNA stabilization following treatment with bortezomib ( = PS-341/Velcade). This peptide boronate inhibitor of the 26S proteasome is very efficient for the treatment of myelomas and other hematological tumors. However, solid tumors are sometimes refractory to bortezomib treatment. We found that depleting CUGBP1 in cancer cells prevents bortezomib-mediated p21 upregulation. FISH experiments combined to mRNA stability assays show that this effect is largely due to a mistargeting of p21 mRNA in stress granules leading to its degradation. Altering the expression of p21 itself, either by depleting CUGBP1 or p21, promotes bortezomib-mediated apoptosis. Conclusions/Significance We propose that one key mechanism by which apoptosis is inhibited upon treatment with chemotherapeutic drugs might involve upregulation of the p21 protein through CUGBP1.
Collapse
|
47
|
Proteasome inhibition induces developmentally deregulated programs of apoptotic and autophagic cell death during Drosophila melanogaster oogenesis. Cell Biol Int 2011; 35:15-27. [PMID: 20819072 DOI: 10.1042/cbi20100191] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Ubiquitin/proteasome-mediated degradation of eukaryotic proteins is critically implicated in a number of signalling pathways and cellular processes. To specifically impair proteasome activities, in vitro developing Drosophila melanogaster egg chambers were exposed to the MG132 or epoxomicin proteasome inhibitors, while a GAL4/UAS binary genetic system was employed to generate double transgenic flies overexpressing β2 and β6 conditional mutant proteasome subunits in a cell type-specific manner. MG132 and epoxomicin administration resulted in severe deregulation of in vitro developing egg chambers, which was tightly associated with precocious induction of nurse cell-specific apoptotic and autophagic death programmes, featured by actin cytoskeleton disorganization, nuclear chromatin condensation, DRICE caspase activation and autophagosome accumulation. In vivo targeted overexpression of β2 and β6 conditional mutants, specifically in the nurse cell compartment, led to a notable up-regulation of sporadic apoptosis potency during early and mid-oogenesis 'checkpoints', thus reasonably justifying the observed reduction in eclosion efficiency. Furthermore, in response to the intracellular abundance of β2 and β6 conditional mutant forms, specifically in numerous tissues of third instar larval stage, the developmental course was arrested, and lethal phenotypes were obtained at this particular embryonic period, with the double transgenic heterozygote embryos being unable to further proceed to complete maturation to adult flies. Our data demonstrate that physiological proteasome function is required to ensure normal oogenesis and embryogenesis in D. melanogaster, since targeted and cell type-dependent proteasome inactivation initiates developmentally deregulated apoptotic and autophagic mechanisms.
Collapse
|
48
|
Irvin WJ, Orlowski RZ, Chiu WK, Carey LA, Collichio FA, Bernard PS, Stijleman IJ, Perou C, Ivanova A, Dees EC. Phase II study of bortezomib and pegylated liposomal doxorubicin in the treatment of metastatic breast cancer. Clin Breast Cancer 2011; 10:465-70. [PMID: 21147690 DOI: 10.3816/cbc.2010.n.061] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Based on preclinical studies and a phase I trial of the combination of bortezomib and pegylated liposomal doxorubicin (PLD), which both showed activity in breast cancer, we conducted a phase II study of this regimen in patients with metastatic breast cancer. PATIENTS AND METHODS Patients received bortezomib 1.3 mg/m2 on days 1, 4, 8, and 11 of an every-21-day cycle, along with PLD 30 mg/m2 on day 4. The primary objective was to evaluate the response rate of this combination, while secondary objectives were to obtain further safety data about this combination, to evaluate the time to disease progression (TTP), and to evaluate response by the breast cancer subtype. RESULTS One of 12 evaluable patients had a partial response (8%), while 3 (25%) had stable disease. At 26 months follow-up, the median overall survival was 4.3 months (95% CI, 1.2-26.2) and the median TTP was 1.3 months (95% CI, 0.8-14.0 months). The combination was well tolerated, with the most common events including low-grade nausea and vomiting, neutropenia, and neuropathy, and no cardiac toxicity was seen. Of the 7 tumors subtyped, no association was seen between intrinsic subtype or receptor status and response. CONCLUSION The combination of PLD and bortezomib was well tolerated but has minimal activity in heavily pretreated unselected metastatic breast cancer.
Collapse
Affiliation(s)
- William J Irvin
- The Lineberger Comprehensive Cancer Center, and Division of Hematology/Oncology, School of Medicine, University of North Carolina at Chapel Hill, 170 Manning Drive, Chapel Hill, NC 27599, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Sacco A, Aujay M, Morgan B, Azab AK, Maiso P, Liu Y, Zhang Y, Azab F, Ngo HT, Issa GC, Quang P, Roccaro AM, Ghobrial IM. Carfilzomib-dependent selective inhibition of the chymotrypsin-like activity of the proteasome leads to antitumor activity in Waldenstrom's Macroglobulinemia. Clin Cancer Res 2011; 17:1753-64. [PMID: 21355079 DOI: 10.1158/1078-0432.ccr-10-2130] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Primary Waldenstrom's Macroglobulinemia (WM) cells present with a significantly higher level of the immunoproteasome compared with the constitutive proteasome. It has been demonstrated that selective inhibition of the chymotrypsin-like (CT-L) activity of constitutive-(c20S) and immuno-(i20S) proteasome represents a valid strategy to induce antineoplastic effect in hematologic tumors. We therefore evaluated carfilzomib, a potent selective, irreversible inhibitor of the CT-L activity of the i20S and c20S in WM cells. EXPERIMENTAL DESIGN We tested the effect of carfilzomib on survival and proliferation of primary WM cells, as well as of other IgM-secreting lymphoma cell lines. Carfilzomib-dependent mechanisms of induced apoptosis in WM cells, and its effect on WM cells in the context of bone marrow (BM) microenvironment have been also evaluated. Moreover, the combinatory effect of carfilzomib and bortezomib has been investigated. In vivo studies have been performed. RESULTS We demonstrated that carfilzomib targeted the CT-L activity of both i20S and c20S, which led to the induction of toxicity in primary WM cells, as well as in other IgM-secreting lymphoma cells. Importantly, carfilzomib targeted WM cells even in the context of BM milieu. In addition, carfilzomib induced apoptosis through c-jun-N-terminal-kinase activation, caspase cleavage, and initiation of unfolded protein response. Importantly, the combination of carfilzomib and bortezomib synergistically inhibited CT-L activity, as well as caspase-, PARP-cleavage and GRP94 expression. Antitumor activity of carfilzomib has been validated in vivo. CONCLUSIONS These findings suggest that targeting i20S and c20S CT-L activity by carfilzomib represents a valid antitumor strategy in WM and other IgM-secreting lymphomas.
Collapse
Affiliation(s)
- Antonio Sacco
- Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Choy MS, Chen MJ, Manikandan J, Peng ZF, Jenner AM, Melendez AJ, Cheung NS. Up-regulation of endoplasmic reticulum stress-related genes during the early phase of treatment of cultured cortical neurons by the proteasomal inhibitor lactacystin. J Cell Physiol 2011; 226:494-510. [PMID: 20683911 DOI: 10.1002/jcp.22359] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Inhibition of proteasome degradation pathway has been implicated in neuronal cell death leading to neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease. We and others demonstrated that treatment of cortical neurons with the proteasomal inhibitor lactacystin leads to apoptosis. We discovered by microarray analysis that lactacystin treatment modulates the expression of both potentially neuroprotective as well as pro-apoptotic genes in neurons. However, the significance of the genes which upon transcriptional modulation contributed to proteasomal inhibition-induced apoptosis, remained unidentified. By employing microarray analysis to decipher the time-dependent changes in transcription of these genes in cultured cortical neurons, we discovered different groups of genes were transcriptionally regulated in the early and late phase of lactacystin-induced cell death. In the early phase, several neuroprotective genes such as those encoding the proteasome subunits and ubiquitin-associated enzymes, as well as the heat-shock proteins (HSP) were up-regulated. However, the pro-apoptotic endoplasmic reticulum (ER) stress-associated genes were also up-regulated at the early phase of lactacystin-induced neuronal cell death. In the late phase, genes encoding antioxidants and calcium-binding proteins were up-regulated while those associated with cholesterol biosynthesis were down-regulated. The data suggest that ER stress may participate in mediating the apoptotic responses induced by proteasomal inhibition. The up-regulation of the neuroprotective antioxidant genes and calcium-binding protein genes and down-regulation of the cholesterol biosynthesis genes in the later phase are likely consequences of stimulation of the pro-apoptotic signaling pathways in the early phase of lactacystin treatment.
Collapse
Affiliation(s)
- Meng Shyan Choy
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | | | | | | | | | | | | |
Collapse
|