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Malek N, Gladysz R, Stelmach N, Drag M. Targeting Microglial Immunoproteasome: A Novel Approach in Neuroinflammatory-Related Disorders. ACS Chem Neurosci 2024; 15:2532-2544. [PMID: 38970802 PMCID: PMC11258690 DOI: 10.1021/acschemneuro.4c00099] [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: 02/15/2024] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 07/08/2024] Open
Abstract
It is widely acknowledged that the aging process is linked to the accumulation of damaged and misfolded proteins. This phenomenon is accompanied by a decrease in proteasome (c20S) activity, concomitant with an increase in immunoproteasome (i20S) activity. These changes can be attributed, in part, to the chronic neuroinflammation that occurs in brain tissues. Neuroinflammation is a complex process characterized by the activation of immune cells in the central nervous system (CNS) in response to injury, infection, and other pathological stimuli. In certain cases, this immune response becomes chronic, contributing to the pathogenesis of various neurological disorders, including chronic pain, Alzheimer's disease, Parkinson's disease, brain traumatic injury, and others. Microglia, the resident immune cells in the brain, play a crucial role in the neuroinflammatory response. Recent research has highlighted the involvement of i20S in promoting neuroinflammation, increased activity of which may lead to the presentation of self-antigens, triggering an autoimmune response against the CNS, exacerbating inflammation, and contributing to neurodegeneration. Furthermore, since i20S plays a role in breaking down accumulated proteins during inflammation within the cell body, any disruption in its activity could lead to a prolonged state of inflammation and subsequent cell death. Given the pivotal role of i20S in neuroinflammation, targeting this proteasome subtype has emerged as a potential therapeutic approach for managing neuroinflammatory diseases. This review delves into the mechanisms of neuroinflammation and microglia activation, exploring the potential of i20S inhibitors as a promising therapeutic strategy for managing neuroinflammatory disorders.
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Affiliation(s)
- Natalia Malek
- Department
of Chemical Biology and Bioimaging, Wroclaw
University of Science and Technology, ul. Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Radoslaw Gladysz
- Department
of Chemical Biology and Bioimaging, Wroclaw
University of Science and Technology, ul. Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Natalia Stelmach
- Department
of Chemical Biology and Bioimaging, Wroclaw
University of Science and Technology, ul. Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - Marcin Drag
- Department
of Chemical Biology and Bioimaging, Wroclaw
University of Science and Technology, ul. Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
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2
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Izadjoo S, Moritz KE, Khayrullina G, Bergman EM, Melvin BM, Stinson MW, Paulson SG, McCormack NM, Anderson KN, Lewis LA, Rotty JD, Burnett BG. Key features of the innate immune response is mediated by the immunoproteasome in microglia. RESEARCH SQUARE 2024:rs.3.rs-4467983. [PMID: 38883799 PMCID: PMC11177974 DOI: 10.21203/rs.3.rs-4467983/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Microglia are the resident immune cells of the central nervous system (CNS). We and others have shown that the inflammatory response of microglia is partially regulated by the immunoproteasome, an inducible form of the proteasome responsible for the generation of major histocompatibility complex (MHC) class I epitopes. While the role of the proteasome in the adaptive immune system is well established, emerging evidence suggests the immunoproteasome may have discrete functions in the innate immune response. Here, we show that inhibiting the immunoproteasome reduces the IFNγ-dependent induction of complement activator C1q, suppresses phagocytosis, and alters the cytokine expression profile in a microglial cell line and microglia derived from human inducible pluripotent stem cells. Moreover, we show that the immunoproteasome regulates the degradation of IκBα, a modulator of NF-κB signaling. Finally, we demonstrate that NADH prevents induction of the immunoproteasome, representing a potential pathway to suppress immunoproteasome-dependent immune responses.
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3
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Targeting immunoproteasome in neurodegeneration: A glance to the future. Pharmacol Ther 2023; 241:108329. [PMID: 36526014 DOI: 10.1016/j.pharmthera.2022.108329] [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: 10/03/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 12/15/2022]
Abstract
The immunoproteasome is a specialized form of proteasome equipped with modified catalytic subunits that was initially discovered to play a pivotal role in MHC class I antigen processing and immune system modulation. However, over the last years, this proteolytic complex has been uncovered to serve additional functions unrelated to antigen presentation. Accordingly, it has been proposed that immunoproteasome synergizes with canonical proteasome in different cell types of the nervous system, regulating neurotransmission, metabolic pathways and adaptation of the cells to redox or inflammatory insults. Hence, studying the alterations of immunoproteasome expression and activity is gaining research interest to define the dynamics of neuroinflammation as well as the early and late molecular events that are likely involved in the pathogenesis of a variety of neurological disorders. Furthermore, these novel functions foster the perspective of immunoproteasome as a potential therapeutic target for neurodegeneration. In this review, we provide a brain and retina-wide overview, trying to correlate present knowledge on structure-function relationships of immunoproteasome with the variety of observed neuro-modulatory functions.
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4
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Avsec D, Škrlj Miklavčič M, Burnik T, Kandušer M, Bizjak M, Podgornik H, Mlinarič-Raščan I. Inhibition of p38 MAPK or immunoproteasome overcomes resistance of chronic lymphocytic leukemia cells to Bcl-2 antagonist venetoclax. Cell Death Dis 2022; 13:860. [PMID: 36209148 PMCID: PMC9547871 DOI: 10.1038/s41419-022-05287-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 09/14/2022] [Accepted: 09/20/2022] [Indexed: 01/23/2023]
Abstract
Chronic lymphocytic leukemia (CLL) is a hematological neoplasm of CD19-positive mature-appearing B lymphocytes. Despite the clinical success of targeted therapies in CLL, the development of resistance diminishes their therapeutic activity. This is also true for the Bcl-2 antagonist venetoclax. We investigated the molecular mechanisms that drive venetoclax resistance in CLL, with a clear focus to provide new strategies to successfully combat it. Activation of CLL cells with IFNγ, PMA/ionomycin, and sCD40L diminished the cytotoxicity of venetoclax. We demonstrated that the metabolic activity of cells treated with 1 nM venetoclax alone was 48% of untreated cells, and was higher for cells co-treated with IFNγ (110%), PMA/ionomycin (78%), and sCD40L (62%). As of molecular mechanism, we showed that PMA/ionomycin and sCD40L triggered translocation of NFκB in primary CLL cells, while IFNγ activated p38 MAPK, suppressed spontaneous and venetoclax-induced apoptosis and induced formation of the immunoproteasome. Inhibition of immunoproteasome with ONX-0914 suppressed activity of immunoproteasome and synergized with venetoclax against primary CLL cells. On the other hand, inhibition of p38 MAPK abolished cytoprotective effects of IFNγ. We demonstrated that venetoclax-resistant (MEC-1 VER) cells overexpressed p38 MAPK and p-Bcl-2 (Ser70), and underexpressed Mcl-1, Bax, and Bak. Inhibition of p38 MAPK or immunoproteasome triggered apoptosis in CLL cells and overcame the resistance to venetoclax of MEC-1 VER cells and venetoclax-insensitive primary CLL cells. In conclusion, the p38 MAPK pathway and immunoproteasome represent novel targets to combat venetoclax resistance in CLL.
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Affiliation(s)
- Damjan Avsec
- grid.8954.00000 0001 0721 6013University of Ljubljana, Faculty of Pharmacy, SI-1000 Ljubljana, Slovenia
| | - Marja Škrlj Miklavčič
- grid.8954.00000 0001 0721 6013University of Ljubljana, Faculty of Pharmacy, SI-1000 Ljubljana, Slovenia
| | - Tilen Burnik
- grid.8954.00000 0001 0721 6013University of Ljubljana, Faculty of Pharmacy, SI-1000 Ljubljana, Slovenia
| | - Maša Kandušer
- grid.8954.00000 0001 0721 6013University of Ljubljana, Faculty of Pharmacy, SI-1000 Ljubljana, Slovenia
| | - Maruša Bizjak
- grid.8954.00000 0001 0721 6013University of Ljubljana, Faculty of Pharmacy, SI-1000 Ljubljana, Slovenia
| | - Helena Podgornik
- grid.8954.00000 0001 0721 6013University of Ljubljana, Faculty of Pharmacy, SI-1000 Ljubljana, Slovenia ,grid.29524.380000 0004 0571 7705University Medical Centre Ljubljana, Department of Haematology, SI-1000 Ljubljana, Slovenia
| | - Irena Mlinarič-Raščan
- grid.8954.00000 0001 0721 6013University of Ljubljana, Faculty of Pharmacy, SI-1000 Ljubljana, Slovenia
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5
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Tripathi SC, Vedpathak D, Ostrin EJ. The Functional and Mechanistic Roles of Immunoproteasome Subunits in Cancer. Cells 2021; 10:cells10123587. [PMID: 34944095 PMCID: PMC8700164 DOI: 10.3390/cells10123587] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 12/15/2022] Open
Abstract
Cell-mediated immunity is driven by antigenic peptide presentation on major histocompatibility complex (MHC) molecules. Specialized proteasome complexes called immunoproteasomes process viral, bacterial, and tumor antigens for presentation on MHC class I molecules, which can induce CD8 T cells to mount effective immune responses. Immunoproteasomes are distinguished by three subunits that alter the catalytic activity of the proteasome and are inducible by inflammatory stimuli such as interferon-γ (IFN-γ). This inducible activity places them in central roles in cancer, autoimmunity, and inflammation. While accelerated proteasomal degradation is an important tumorigenic mechanism deployed by several cancers, there is some ambiguity regarding the role of immunoproteasome induction in neoplastic transformation. Understanding the mechanistic and functional relevance of the immunoproteasome provides essential insights into developing targeted therapies, including overcoming resistance to standard proteasome inhibition and immunomodulation of the tumor microenvironment. In this review, we discuss the roles of the immunoproteasome in different cancers.
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Affiliation(s)
- Satyendra Chandra Tripathi
- Department of Biochemistry, All India Institute of Medical Sciences Nagpur, Nagpur 441108, MH, India;
- Correspondence: (S.C.T.); (E.J.O.)
| | - Disha Vedpathak
- Department of Biochemistry, All India Institute of Medical Sciences Nagpur, Nagpur 441108, MH, India;
| | - Edwin Justin Ostrin
- Department of General Internal Medicine, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Correspondence: (S.C.T.); (E.J.O.)
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6
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Gatekeepers of the Gut: The Roles of Proteasomes at the Gastrointestinal Barrier. Biomolecules 2021; 11:biom11070989. [PMID: 34356615 PMCID: PMC8301830 DOI: 10.3390/biom11070989] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 06/28/2021] [Accepted: 06/29/2021] [Indexed: 12/24/2022] Open
Abstract
The gut epithelial barrier provides the first line of defense protecting the internal milieu from the environment. To circumvent the exposure to constant challenges such as pathogenic infections and commensal bacteria, epithelial and immune cells at the gut barrier require rapid and efficient means to dynamically sense and respond to stimuli. Numerous studies have highlighted the importance of proteolysis in maintaining homeostasis and adapting to the dynamic changes of the conditions in the gut environment. Primarily, proteolytic activities that are involved in immune regulation and inflammation have been examined in the context of the lysosome and inflammasome activation. Yet, the key to cellular and tissue proteostasis is the ubiquitin–proteasome system, which tightly regulates fundamental aspects of inflammatory signaling and protein quality control to provide rapid responses and protect from the accumulation of proteotoxic damage. In this review, we discuss proteasome-dependent regulation of the gut and highlight the pathophysiological consequences of the disarray of proteasomal control in the gut, in the context of aberrant inflammatory disorders and tumorigenesis.
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7
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Krishnan R, Kim JO, Jang YS, Oh MJ. Proteasome subunit beta type-8 from sevenband grouper negatively regulates cytokine responses by interfering NF-κB signaling upon nervous necrosis viral infection. FISH & SHELLFISH IMMUNOLOGY 2021; 113:118-124. [PMID: 33848637 DOI: 10.1016/j.fsi.2021.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 03/23/2021] [Accepted: 04/06/2021] [Indexed: 06/12/2023]
Abstract
During viral infection, proper regulation of immune signaling is essential to ensure successful clearance of virus. Immunoproteasome is constitutively expressed and gets induced during viral infection by interferon signaling and contributes to regulate proinflammatory cytokine production and activation of the NF-κB pathway. In this study, we identified Hs-PSMB8, a member of the proteasome β-subunits (PSMB) family, as a negative regulator of NF-κB responses during NNV infection. The transient expression of Hs-PSMB8 delayed the appearance of cytopathic effect (CPE) and showed a higher viral load. The Hs-PSMB8 interacted with NNV which was confirmed using immunocolocalization and co-IP. Overexpression of Hs-PSMB8 diminished virus induced activation of the NF-κB promoters and downregulated the activation of IL-1β, TNFα, IL6, IL8, IFNγ expression upon NNV infection. Collectively, our results demonstrate that PSMB8 is an important regulator of NF-κB signaling during NNV infection in sevenband grouper.
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Affiliation(s)
- Rahul Krishnan
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Republic of Korea
| | - Jong-Oh Kim
- Institute of Marine Biotechnology, Pukyong National University, Busan, Republic of Korea.
| | - Yo-Seb Jang
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Republic of Korea
| | - Myung-Joo Oh
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Republic of Korea.
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8
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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.
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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
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9
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Beling A, Kespohl M. Proteasomal Protein Degradation: Adaptation of Cellular Proteolysis With Impact on Virus-and Cytokine-Mediated Damage of Heart Tissue During Myocarditis. Front Immunol 2018; 9:2620. [PMID: 30546359 PMCID: PMC6279938 DOI: 10.3389/fimmu.2018.02620] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 10/24/2018] [Indexed: 12/26/2022] Open
Abstract
Viral myocarditis is an inflammation of the heart muscle triggered by direct virus-induced cytolysis and immune response mechanisms with most severe consequences during early childhood. Acute and long-term manifestation of damaged heart tissue and disturbances of cardiac performance involve virus-triggered adverse activation of the immune response and both immunopathology, as well as, autoimmunity account for such immune-destructive processes. It is a matter of ongoing debate to what extent subclinical virus infection contributes to the debilitating sequela of the acute disease. In this review, we conceptualize the many functions of the proteasome in viral myocarditis and discuss the adaptation of this multi-catalytic protease complex together with its implications on the course of disease. Inhibition of proteasome function is already highly relevant as a strategy in treating various malignancies. However, cardiotoxicity and immune-related adverse effects have proven significant hurdles, representative of the target's wide-ranging functions. Thus, we further discuss the molecular details of proteasome-mediated activity of the immune response for virus-mediated inflammatory heart disease. We summarize how the spatiotemporal flexibility of the proteasome might be tackled for therapeutic purposes aiming to mitigate virus-mediated adverse activation of the immune response in the heart.
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Affiliation(s)
- Antje Beling
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Institute of Biochemistry, Berlin, Germany.,Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), Partner Site Berlin, Berlin, Germany
| | - Meike Kespohl
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Institute of Biochemistry, Berlin, Germany.,Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), Partner Site Berlin, Berlin, Germany
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10
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González Y, Doens D, Cruz H, Santamaría R, Gutiérrez M, Llanes A, Fernández PL. A Marine Diterpenoid Modulates the Proteasome Activity in Murine Macrophages Stimulated with LPS. Biomolecules 2018; 8:E109. [PMID: 30301161 PMCID: PMC6315684 DOI: 10.3390/biom8040109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 09/14/2018] [Accepted: 10/01/2018] [Indexed: 11/17/2022] Open
Abstract
The proteasome is an intracellular complex that degrades damaged or unfolded proteins and participates in the regulation of several processes. The immunoproteasome is a specialized form that is expressed in response to proinflammatory signals and is particularly abundant in immune cells. In a previous work, we found an anti-inflammatory effect in a diterpenoid extracted from the octocoral Pseudopterogorgia acerosa, here called compound 1. This compound prevented the degradation of inhibitor κB α (IκBα) and the subsequent activation of nuclear factor κB (NFκB), suggesting that this effect might be due to inhibition of the ubiquitin-proteasome system. Here we show that compound 1 inhibits the proteasomal chymotrypsin-like activity (CTL) of murine macrophages in the presence of lipopolysaccharide (LPS) but not in its absence. This effect might be due to the capacity of this compound to inhibit the activity of purified immunoproteasome. The compound inhibits the cell surface expression of major histocompatibility complex (MHC)-I molecules and the production of proinflammatory cytokines induced by LPS in vitro and in vivo, respectively. Molecular docking simulations predicted that compound 1 selectively binds to the catalytic site of immunoproteasome subunits β1i and β5i, which are responsible for the CTL activity. Taken together these findings suggest that the compound could be a selective inhibitor of the immunoproteasome, and hence could pave the way for its future evaluation as a candidate for the treatment of inflammatory disorders and autoimmune diseases.
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Affiliation(s)
- Yisett González
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP),Edificio 219, Ciudad del Saber, 0801 Panamá, Panamá.
| | - Deborah Doens
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP),Edificio 219, Ciudad del Saber, 0801 Panamá, Panamá.
| | - Héctor Cruz
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP),Edificio 219, Ciudad del Saber, 0801 Panamá, Panamá.
- Facultad de Ciencias de la Salud Dr. William C. Gorgas, Universidad Latina de Panamá, 0801 Panamá, Panamá.
| | - Ricardo Santamaría
- Centro de Biodiversidad y Descubrimiento de Drogas, INDICASAT AIP, Edificio 219, Ciudad del Saber, 0801 Panamá, Panamá.
| | - Marcelino Gutiérrez
- Centro de Biodiversidad y Descubrimiento de Drogas, INDICASAT AIP, Edificio 219, Ciudad del Saber, 0801 Panamá, Panamá.
| | - Alejandro Llanes
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP),Edificio 219, Ciudad del Saber, 0801 Panamá, Panamá.
| | - Patricia L Fernández
- Centro de Biología Celular y Molecular de Enfermedades, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP),Edificio 219, Ciudad del Saber, 0801 Panamá, Panamá.
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11
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Immunoproteasome subunit deficiency has no influence on the canonical pathway of NF-κB activation. Mol Immunol 2017; 83:147-153. [PMID: 28157553 DOI: 10.1016/j.molimm.2017.01.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/13/2017] [Accepted: 01/20/2017] [Indexed: 01/02/2023]
Abstract
Activation of the pro-inflammatory transcription factor NF-κB requires signal-induced proteasomal degradation of the inhibitor of NF-κB (IκB) in order to allow nuclear translocation. Most cell types are capable of expressing two types of 20S proteasome core particles, the constitutive proteasome and immunoproteasome. Inducible under inflammatory conditions, the immunoproteasome is mainly characterized through an altered cleavage specificity compared to the constitutive proteasome. However, the question whether immunoproteasome subunits affect NF-κB signal transduction differently from constitutive subunits is still up for debate. To study the effect of immunoproteasomes on LPS- or TNF-α-induced NF-κB activation, we used IFN-γ stimulated peritoneal macrophages and mouse embryonic fibroblasts derived from mice deficient for the immunoproteasome subunits low molecular mass polypeptide (LMP) 2, or LMP7 and multicatalytic endopeptidase complex-like 1 (MECL-1). Along the canonical signaling pathway of NF-κB activation no differences in the extent and kinetic of IκB degradation were observed. Neither the nuclear translocation and DNA binding of NF-κB nor the production of the NF-κB dependent cytokines TNF-α, IL-6, and IL-10 differed between immunoproteasome deficient and proficient cells. Hence, we conclude that immunoproteasome subunits have no specialized function for canonical NF-κB activation.
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12
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Kammerl IE, Meiners S. Proteasome function shapes innate and adaptive immune responses. Am J Physiol Lung Cell Mol Physiol 2016; 311:L328-36. [PMID: 27343191 DOI: 10.1152/ajplung.00156.2016] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/17/2016] [Indexed: 11/22/2022] Open
Abstract
The proteasome system degrades more than 80% of intracellular proteins into small peptides. Accordingly, the proteasome is involved in many essential cellular functions, such as protein quality control, transcription, immune responses, cell signaling, and apoptosis. Moreover, degradation products are loaded onto major histocompatibility class I molecules to communicate the intracellular protein composition to the immune system. The standard 20S proteasome core complex contains three distinct catalytic active sites that are exchanged upon stimulation with inflammatory cytokines to form the so-called immunoproteasome. Immunoproteasomes are constitutively expressed in immune cells and have different proteolytic activities compared with standard proteasomes. They are rapidly induced in parenchymal cells upon intracellular pathogen infection and are crucial for priming effective CD8(+) T-cell-mediated immune responses against infected cells. Beyond shaping these adaptive immune reactions, immunoproteasomes also regulate the function of immune cells by degradation of inflammatory and immune mediators. Accordingly, they emerge as novel regulators of innate immune responses. The recently unraveled impairment of immunoproteasome function by environmental challenges and by genetic variations of immunoproteasome genes might represent a currently underestimated risk factor for the development and progression of lung diseases. In particular, immunoproteasome dysfunction will dampen resolution of infections, thereby promoting exacerbations, may foster autoimmunity in chronic lung diseases, and possibly contributes to immune evasion of tumor cells. Novel pharmacological tools, such as site-specific inhibitors of the immunoproteasome, as well as activity-based probes, however, hold promises as innovative therapeutic drugs for respiratory diseases and biomarker profiling, respectively.
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Affiliation(s)
- Ilona E Kammerl
- Comprehensive Pneumology Center, University Hospital, Ludwig-Maximilians University and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Silke Meiners
- Comprehensive Pneumology Center, University Hospital, Ludwig-Maximilians University and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
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13
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Emerging role of immunoproteasomes in pathophysiology. Immunol Cell Biol 2016; 94:812-820. [PMID: 27192937 DOI: 10.1038/icb.2016.50] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 05/15/2016] [Accepted: 05/16/2016] [Indexed: 11/08/2022]
Abstract
The immunoproteasome is a proteasome variant that is found only in jawed vertebrates. It is responsible for degrading intracellular proteins to generate a major source of peptides with substantial major histocompatibility complex I binding affinity. The immunoproteasome also has roles in T-cell survival, differentiation and proliferation in various pathological conditions. In humans, any alteration in the expression, assembly or function of the immunoproteasome can lead to cancer, autoimmune disorders or inflammatory diseases. Although the roles of the immunoproteasome in cancer and neurodegenerative disorders have been extensively studied, its significance in other disease conditions has only recently become known. Therefore, there is renewed interest in the development of drugs, vaccines and biomarkers that target the immunoproteasome. The current review highlights the involvement of this complex in disease pathology in addition to the advances made in immunoproteasome research.
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14
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Chen S, Kammerl IE, Vosyka O, Baumann T, Yu Y, Wu Y, Irmler M, Overkleeft HS, Beckers J, Eickelberg O, Meiners S, Stoeger T. Immunoproteasome dysfunction augments alternative polarization of alveolar macrophages. Cell Death Differ 2016; 23:1026-37. [PMID: 26990663 PMCID: PMC4987736 DOI: 10.1038/cdd.2016.3] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 12/22/2015] [Accepted: 01/11/2016] [Indexed: 02/04/2023] Open
Abstract
The proteasome is a central regulatory hub for intracellular signaling by degrading numerous signaling mediators. Immunoproteasomes are specialized types of proteasomes involved in shaping adaptive immune responses, but their role in innate immune signaling is still elusive. Here, we analyzed immunoproteasome function for polarization of alveolar macrophages, highly specialized tissue macrophages of the alveolar lung surface. Classical activation (M1 polarization) of primary alveolar macrophages by LPS/IFNγ transcriptionally induced all three immunoproteasome subunits, low molecular mass protein 2 (LMP2), LMP7 and multicatalytic endopeptidase complex-like 1, which was accompanied by increased immunoproteasome activity in M1 cells. Deficiency of LMP7 had no effect on the LPS/IFNγ-triggered M1 profile indicating that immunoproteasome function is dispensable for classical alveolar macrophage activation. In contrast, IL-4 triggered alternative (M2) activation of primary alveolar macrophages was accompanied by a transcriptionally independent amplified expression of LMP2 and LMP7 and an increase in immunoproteasome activity. Alveolar macrophages from LMP7 knockout mice disclosed a distorted M2 profile upon IL-4 stimulation as characterized by increased M2 marker gene expression and CCL17 cytokine release. Comparative transcriptome analysis revealed enrichment of IL-4-responsive genes and of genes involved in cellular response to defense, wounding and inflammation in LMP7-deficient alveolar macrophages indicating a distinct M2 inflammation resolving phenotype. Moreover, augmented M2 polarization was accompanied by amplified AKT/STAT6 activation and increased RNA and protein expression of the M2 master transcription factor interferon regulatory factor 4 in LMP7(-/-) alveolar macrophages. IL-13 stimulation of LMP7-deficient macrophages induced a similar M2-skewed profile indicative for augmented signaling via the IL-4 receptor α (IL4Rα). IL4Rα expression was generally elevated only on protein but not RNA level in LMP7(-/-) alveolar macrophages. Importantly, specific catalytic inhibition with an LMP7-specific proteasome inhibitor confirmed augmented IL-4-mediated M2 polarization of alveolar macrophages. Our results thus suggest a novel role of immunoproteasome function for regulating alternative activation of macrophages by limiting IL4Rα expression and signaling.
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Affiliation(s)
- S Chen
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Neuherberg, Germany
- Department of Pathophysiology, West China School of Preclinical Sciences and Forensic Medicine, Sichuan University, Chengdu, Sichuan Province, China
| | - I E Kammerl
- Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
| | - O Vosyka
- Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
| | - T Baumann
- Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
| | - Y Yu
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Neuherberg, Germany
| | - Y Wu
- Max von Pettenkofer-Institute, Ludwig-Maximilians University, Munich, Germany
| | - M Irmler
- Institute of Experimental Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - H S Overkleeft
- Department of Bio-Organic Synthesis, Leiden University, Leiden, The Netherlands
| | - J Beckers
- Institute of Experimental Genetics, Helmholtz Zentrum München GmbH, Neuherberg, Germany
- German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany
- Technische Universität München, Chair of Experimental Genetics, Freising, Germany
| | - O Eickelberg
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Neuherberg, Germany
- Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
| | - S Meiners
- Comprehensive Pneumology Center (CPC), University Hospital, Ludwig-Maximilians University and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Munich, Germany
| | - T Stoeger
- Comprehensive Pneumology Center (CPC), Institute of Lung Biology and Disease, Helmholtz Zentrum München, Neuherberg, Germany
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15
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Paeschke A, Possehl A, Klingel K, Voss M, Voss K, Kespohl M, Sauter M, Overkleeft HS, Althof N, Garlanda C, Voigt A. The immunoproteasome controls the availability of the cardioprotective pattern recognition molecule Pentraxin3. Eur J Immunol 2015; 46:619-33. [PMID: 26578407 DOI: 10.1002/eji.201545892] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 10/19/2015] [Accepted: 11/10/2015] [Indexed: 12/20/2022]
Abstract
Cardiomyocyte death as a result of viral infection is an excellent model for dissecting the inflammatory stress response that occurs in heart tissue. We reported earlier that a specific proteasome isoform, the immunoproteasome, prevents exacerbation of coxsackievirus B3 (CVB3)-induced myocardial destruction and preserves cell vitality in heart tissue inflammation. Following the aim to decipher molecular targets of immunoproteasome-dependent proteolysis, we investigated the function and regulation of the soluble PRR Pentraxin3 (PTX3). We show that the ablation of PTX3 in mice aggravated CVB3-triggered inflammatory injury of heart tissue, without having any significant effect on viral titers. Thus, there might be a role of PTX3 in preventing damage-associated molecular pattern-induced cell death. We found that the catalytic activity of the immunoproteasome subunit LMP7 regulates the timely availability of factors controlling PTX3 production. We report on immunoproteasome-dependent alteration of ERK1/2 and p38MAPKs, which were both found to be involved in PTX3 expression control. Our finding of a cardioprotective function of immunoproteasome-dependent PTX3 expression revealed a crucial mechanism of the stress-induced damage response in myocardial inflammation. In addition to antigen presentation and cytokine production, proteolysis by the immunoproteasome can also regulate the innate immune response during viral infection.
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Affiliation(s)
- Anna Paeschke
- Institut für Biochemie, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Anna Possehl
- Institut für Biochemie, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Karin Klingel
- Institut für Molekulare Pathologie, Universitätsklinikum Tübingen, Tübingen, Germany
| | - Martin Voss
- Institut für Biochemie, Charité Universitätsmedizin Berlin, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Side Berlin, Berlin, Germany
| | - Karolin Voss
- Institut für Biochemie, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Meike Kespohl
- Institut für Biochemie, Charité Universitätsmedizin Berlin, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Side Berlin, Berlin, Germany
| | - Martina Sauter
- Institut für Molekulare Pathologie, Universitätsklinikum Tübingen, Tübingen, Germany
| | | | - Nadine Althof
- Institut für Biochemie, Charité Universitätsmedizin Berlin, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Side Berlin, Berlin, Germany
| | | | - Antje Voigt
- Institut für Biochemie, Charité Universitätsmedizin Berlin, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Side Berlin, Berlin, Germany
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16
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Schuld NJ, Hussong SA, Kapphahn RJ, Lehmann U, Roehrich H, Rageh AA, Heuss ND, Bratten W, Gregerson DS, Ferrington DA. Immunoproteasome deficiency protects in the retina after optic nerve crush. PLoS One 2015; 10:e0126768. [PMID: 25978061 PMCID: PMC4433222 DOI: 10.1371/journal.pone.0126768] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 04/07/2015] [Indexed: 01/31/2023] Open
Abstract
The immunoproteasome is upregulated by disease, oxidative stress, and inflammatory cytokines, suggesting an expanded role for the immunoproteasome in stress signaling that goes beyond its canonical role in generating peptides for antigen presentation. The signaling pathways that are regulated by the immunoproteasome remain elusive. However, previous studies suggest a role for the immunoproteasome in the regulation of PTEN and NF-κB signaling. One well-known pathway upstream of NF-κB and downstream of PTEN is the Akt signaling pathway, which is responsible for mediating cellular survival and is modulated after optic nerve crush (ONC). This study investigated the role of retinal immunoproteasome after injury induced by ONC, focusing on the Akt cell survival pathway. Retinas or retinal pigment epithelial (RPE) cells from wild type (WT) and knockout (KO) mice lacking either one (LMP2) or two (LMP7 and MECL-1) catalytic subunits of the immunoproteasome were utilized in this study. We show that mRNA and protein levels of the immunoproteasome subunits are significantly upregulated in WT retinas following ONC. Mice lacking the immunoproteasome subunits show either a delayed or dampened apoptotic response as well as altered Akt signaling, compared to WT mice after ONC. Treatment of the RPE cells with insulin growth factor-1 (IGF-1) to stimulate Akt signaling confirmed that the immunoproteasome modulates this pathway, and most likely modulates parallel pathways as well. This study links the inducible expression of the immunoproteasome following retinal injury to Akt signaling, which is important in many disease pathways.
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Affiliation(s)
- Nathan J. Schuld
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Stacy A. Hussong
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
- Graduate Program in Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Rebecca J. Kapphahn
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Ute Lehmann
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
- Graduate Program in Microbiology, Immunology and Cancer Biology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Heidi Roehrich
- Histology Core for Vision Research, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Abrar A. Rageh
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Neal D. Heuss
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Wendy Bratten
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Dale S. Gregerson
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Deborah A. Ferrington
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
- * E-mail:
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17
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McCarthy MK, Weinberg JB. The immunoproteasome and viral infection: a complex regulator of inflammation. Front Microbiol 2015; 6:21. [PMID: 25688236 PMCID: PMC4310299 DOI: 10.3389/fmicb.2015.00021] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 01/08/2015] [Indexed: 11/13/2022] Open
Abstract
During viral infection, proper regulation of immune responses is necessary to ensure successful viral clearance with minimal host tissue damage. Proteasomes play a crucial role in the generation of antigenic peptides for presentation on MHC class I molecules, and thus activation of CD8 T cells, as well as activation of the NF-κB pathway. A specialized type of proteasome called the immunoproteasome is constitutively expressed in hematopoietic cells and induced in non-immune cells during viral infection by interferon signaling. The immunoproteasome regulates CD8 T cell responses to many viral epitopes during infection. Accumulating evidence suggests that the immunoproteasome may also contribute to regulation of proinflammatory cytokine production, activation of the NF-κB pathway, and management of oxidative stress. Many viruses have mechanisms of interfering with immunoproteasome function, including prevention of transcriptional upregulation of immunoproteasome components as well as direct interaction of viral proteins with immunoproteasome subunits. A better understanding of the role of the immunoproteasome in different cell types, tissues, and hosts has the potential to improve vaccine design and facilitate the development of effective treatment strategies for viral infections.
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Affiliation(s)
- Mary K McCarthy
- Department of Microbiology and Immunology, University of Michigan Ann Arbor, MI, USA
| | - Jason B Weinberg
- Department of Microbiology and Immunology, University of Michigan Ann Arbor, MI, USA ; Department of Pediatrics and Communicable Diseases, University of Michigan Ann Arbor, MI, USA
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18
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Miller Z, Ao L, Kim KB, Lee W. Inhibitors of the immunoproteasome: current status and future directions. Curr Pharm Des 2014. [PMID: 23181576 DOI: 10.2174/1381612811319220018] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ubiquitin-proteasome system (UPS) plays a vital role in maintaining protein homeostasis and regulating numerous cellular processes. The proteasome, a multi-protease complex, is the key component of the UPS and has been validated as a therapeutic target by the FDA's approval of bortezomib and carfilzomib. These proteasome inhibitor drugs have substantially improved outcomes in patients with hematological malignancies and are currently being investigated for other types of cancer as well as several other diseases. These approved proteasome inhibitors target the catalytic activity of both the constitutive proteasome and the immunoproteasome indiscriminately, and their inhibitory effects on the constitutive proteasome in normal cells are believed to contribute to unwanted side effects. In addition, selective immunoproteasome inhibition has been proposed to have unique effects on other diseases, including those involving aberrant immune function. Initially recognized for its role in the adaptive immune response, the immunoproteasome is often upregulated in disease states such as inflammatory diseases and cancer, suggesting functions beyond antigen presentation. In an effort to explore the immunoproteasome as a potential therapeutic target in these diseases, the development of immunoproteasome-specific inhibitors has become the focus of recent studies. Owing to considerable efforts by both academic and industry groups, immunoproteasome-selective inhibitors have now been identified and tested against several disease models. These inhibitors also provide a valuable set of chemical tools for investigating the biological function of the immunoproteasome. In this review, we will focus on the recent efforts towards the development of immunoproteasome-selective inhibitors.
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Affiliation(s)
- Zachary Miller
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone, Lexington, Kentucky 40536-0596, USA
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19
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Identification of the immunoproteasome as a novel regulator of skeletal muscle differentiation. Mol Cell Biol 2013; 34:96-109. [PMID: 24164898 DOI: 10.1128/mcb.00622-13] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
While many of the molecular details of myogenesis have been investigated extensively, the function of immunoproteasomes (i-proteasomes) in myogenic differentiation remains unknown. We show here that the mRNA of i-proteasome subunits, the protein levels of constitutive and inducible proteasome subunits, and the proteolytic activities of the 20S and 26S proteasomes were significantly upregulated during differentiation of skeletal muscle C2C12 cells. Knockdown of the i-proteasome catalytic subunit PSMB9 by short hairpin RNA (shRNA) decreased the expression of both PSMB9 and PSMB8 without affecting other catalytic subunits of the proteasome. PSMB9 knockdown and the use of i-proteasome-specific inhibitors both decreased 26S proteasome activities and prevented C2C12 differentiation. Inhibition of the i-proteasome also impaired human skeletal myoblast differentiation. Suppression of the i-proteasome increased protein oxidation, and these oxidized proteins were found to be more susceptible to degradation by exogenous i-proteasomes. Downregulation of the i-proteasome also increased proapoptotic proteins, including Bax, as well as cleaved caspase 3, cleaved caspase 9, and cleaved poly(ADP-ribose) polymerase (PARP), suggesting that impaired differentiation is likely to occur because of significantly increased apoptosis. These results demonstrate for the first time that i-proteasomes, independent of constitutive proteasomes, are critical for skeletal muscle differentiation of mouse C2C12 cells.
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20
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Park JE, Ao L, Miller Z, Kim K, Wu Y, Jang ER, Lee EY, Kim KB, Lee W. PSMB9 codon 60 polymorphisms have no impact on the activity of the immunoproteasome catalytic subunit B1i expressed in multiple types of solid cancer. PLoS One 2013; 8:e73732. [PMID: 24040045 PMCID: PMC3767749 DOI: 10.1371/journal.pone.0073732] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/20/2013] [Indexed: 11/18/2022] Open
Abstract
The proteasome is a key regulator of cellular protein homeostasis and is a clinically validated anticancer target. The immunoproteasome, a subtype of proteasome expressed mainly in hematopoietic cells, was initially recognized for its role in antigen presentation during the immune response. Recently, the immunoproteasome has been implicated in several disease conditions including cancer and autoimmune disorders, but many of the factors contributing to these pathological processes remain unknown. In particular, the codon 60 polymorphism of the PSMB9 gene encoding the β1i immunoproteasome catalytic subunit has been investigated in the context of a variety of diseases. Despite this, previous studies have so far reported inconsistent findings regarding the impact of this polymorphism on proteasome activity. Thus, we set out to investigate the impact of the PSMB9 codon 60 polymorphism on the expression and activity of the β1i immunoproteasome subunit in a panel of human cancer cell lines. The β1i-selective fluorogenic substrate Acetyl-Pro-Ala-Leu-7-amino-4-methylcoumarin was used to specifically measure β1i catalytic activity. Our results indicate that the codon 60 Arg/His polymorphism does not significantly alter the expression and activity of β1i among the cell lines tested. Additionally, we also examined the expression of β1i in clinical samples from colon and pancreatic cancer patients. Our immunohistochemical analyses showed that ∼70% of clinical colon cancer samples and ∼53% of pancreatic cancer samples have detectable β1i expression. Taken together, our results indicate that the β1i subunit of the immunoproteasome is frequently expressed in colon and pancreatic cancers but that the codon 60 genetic variants of β1i display similar catalytic activities and are unlikely to contribute to the significant inter-cell-line and inter-individual variabilities in the immunoproteasome activity.
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Affiliation(s)
- Ji Eun Park
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America
| | - Lin Ao
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America
| | - Zachary Miller
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America
| | - Kyungbo Kim
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America
| | - Ying Wu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America
| | - Eun Ryoung Jang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America
| | - Eun Young Lee
- Department of Pathology and Laboratory Medicine, College of Medicine, University of Kentucky, Lexington, Kentucky, United States of America
| | - Kyung Bo Kim
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America
| | - Wooin Lee
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, United States of America
- * E-mail:
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21
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Han S, Kim K, Thakkar N, Kim D, Lee W. Role of hypoxia inducible factor-1α in the regulation of the cancer-specific variant of organic anion transporting polypeptide 1B3 (OATP1B3), in colon and pancreatic cancer. Biochem Pharmacol 2013; 86:816-23. [PMID: 23924606 DOI: 10.1016/j.bcp.2013.07.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 07/21/2013] [Accepted: 07/23/2013] [Indexed: 01/29/2023]
Abstract
Organic anion transporting polypeptide 1B3 (OATP1B3) was initially considered to be a liver-specific transporter, mediating the uptake of a variety of endogenous and xenobiotic substances. Over the past decade, several investigations reported that OATP1B3 is also expressed across multiple types of cancers. Only recently, our laboratory and others demonstrated the identity of cancer-specific OATP1B3 variants (csOATP1B3) arising from the use of an alternative transcription initiation site, different from the wildtype (WT) OATP1B3 expressed in the normal liver. However, the mechanisms regulating the expression of csOATP1B3 remained unknown. In our current study, we investigated the role of hypoxia and the involvement of hypoxia inducible factor-1α (HIF-1α) in regulating the transcription of csOATP1B3. Our RT-PCR and immunoblotting results indicated that csOATP1B3, but not WT OATP1B3, can be induced in response to ambient or chemical hypoxia (upon exposure to 1% O₂ or cobalt chloride). Reporter assays with deletion and mutated constructs of the csOATP1B3 promoter revealed a functional hypoxia response element (HRE) located in the proximal upstream region. Constructs harboring the HRE displayed the upregulated reporter gene expression in response to hypoxia, but not when mutated. Electrophoretic mobility shift assays using a biotin-labeled csOATP1B3 promoter HRE probe indicated the binding of HIF-1α, which was blocked by an excess of unlabeled csOATP1B3 probe. Furthermore, siRNA-based knockdown of HIF-1α caused a substantial decrease in the expression level of csOATP1B3. Taken together, these findings demonstrate that the transcription of csOATP1B3 is actively engaged during hypoxia, through a commonly utilized pathway involving HIF-1α.
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Affiliation(s)
- Songhee Han
- Department of Biological Sciences, Konkuk University, Seoul 143-701, Republic of Korea
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22
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Maldonado M, Kapphahn RJ, Terluk MR, Heuss ND, Yuan C, Gregerson DS, Ferrington DA. Immunoproteasome deficiency modifies the alternative pathway of NFκB signaling. PLoS One 2013; 8:e56187. [PMID: 23457524 PMCID: PMC3572990 DOI: 10.1371/journal.pone.0056187] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 01/10/2013] [Indexed: 11/19/2022] Open
Abstract
Immunoproteasome is a protease abundant in immune cells and also present, albeit at lower concentrations, in cells outside the immune system. Recent evidence supports a novel role for the immunoproteasome in the cellular stress response potentially through regulation of NFκB signaling, which is the primary response to multiple stressors. The current study tests whether the Classical or Alternative Pathways are regulated by immunoproteasome following chronic TNFα exposure in cultured retinal pigment epithelial cells isolated from wild-type mice and mice deficient in one (LMP2, L2) or two (LMP7 and MECL-1, L7M1) immunoproteasome subunits. Assays were performed to assess the expression of NFκB responsive genes, the content and activity of NFκB transcription factors (p65, p50, p52, cRel, RelB), and expression and content of regulatory proteins (IκBα, A20, RPS3). Major findings include distinct differences in expression of NFκB responsive genes in both KO cells. The mechanism responsible for the altered gene expression could not be established for L7M1 since no major differences in NFκB transcription factor content or activation were observed. However, L2 cells exhibited substantially higher content and diminished activation of NFκB transcription factors associated with the Alternative Pathway and delayed termination of the Classical Pathway. These results provide strong experimental evidence supporting a role for immunoproteasome in modulating NFκB signaling.
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Affiliation(s)
- Marcela Maldonado
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Rebecca J. Kapphahn
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Marcia R. Terluk
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Neal D. Heuss
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Ching Yuan
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Dale S. Gregerson
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Deborah A. Ferrington
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, Minnesota, United States of America
- * E-mail:
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23
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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.
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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.
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24
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The immunoproteasome in antigen processing and other immunological functions. Curr Opin Immunol 2012; 25:74-80. [PMID: 23219269 DOI: 10.1016/j.coi.2012.11.004] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 11/12/2012] [Accepted: 11/13/2012] [Indexed: 01/30/2023]
Abstract
Treatment of cells with interferon-γ leads to the replacement of the constitutive catalytic proteasome subunits β1, β2, and β5 by the inducible subunits LMP2 (β1i), MECL-1 (β2i), and LMP7 (β5i), respectively, building the so-called immunoproteasome. The incorporation of these subunits is required for the production of numerous MHC class-I restricted T cell epitopes. Recently, new evidence for an involvement of the immunoproteasome in other facets of the immune response emerged. Investigations of autoimmune diseases in animal models and a genetic predisposition of β5i in human autoimmune disorders suggest a crucial function of the immunoproteasome in proinflammatory diseases. The recent elucidation of the high-resolution structure of the immunoproteasome will facilitate the design of immunoproteasome selective inhibitors for pharmacological intervention.
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