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Patil H, Yi H, Cho KI, Ferreira PA. Proteostatic Remodeling of Small Heat Shock Chaperones─Crystallins by Ran-Binding Protein 2─and the Peptidyl-Prolyl cis-trans Isomerase and Chaperone Activities of Its Cyclophilin Domain. ACS Chem Neurosci 2024; 15:1967-1989. [PMID: 38657106 DOI: 10.1021/acschemneuro.3c00792] [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] [Indexed: 04/26/2024] Open
Abstract
Disturbances in protein phase transitions promote protein aggregation─a neurodegeneration hallmark. The modular Ran-binding protein 2 (Ranbp2) is a cytosolic molecular hub for rate-limiting steps of phase transitions of Ran-GTP-bound protein ensembles exiting nuclear pores. Chaperones also regulate phase transitions and proteostasis by suppressing protein aggregation. Ranbp2 haploinsufficiency promotes the age-dependent neuroprotection of the chorioretina against phototoxicity by proteostatic regulations of neuroprotective substrates of Ranbp2 and by suppressing the buildup of polyubiquitylated substrates. Losses of peptidyl-prolyl cis-trans isomerase (PPIase) and chaperone activities of the cyclophilin domain (CY) of Ranbp2 recapitulate molecular effects of Ranbp2 haploinsufficiency. These CY impairments also stimulate deubiquitylation activities and phase transitions of 19S cap subunits of the 26S proteasome that associates with Ranbp2. However, links between CY moonlighting activity, substrate ubiquitylation, and proteostasis remain incomplete. Here, we reveal the Ranbp2 regulation of small heat shock chaperones─crystallins in the chorioretina by proteomics of mice with total or selective modular deficits of Ranbp2. Specifically, loss of CY PPIase of Ranbp2 upregulates αA-Crystallin, which is repressed in adult nonlenticular tissues. Conversely, impairment of CY's chaperone activity opposite to the PPIase pocket downregulates a subset of αA-Crystallin's substrates, γ-crystallins. These CY-dependent effects cause age-dependent and chorioretinal-selective declines of ubiquitylated substrates without affecting the chorioretinal morphology. A model emerges whereby inhibition of Ranbp2's CY PPIase remodels crystallins' expressions, subdues molecular aging, and preordains the chorioretina to neuroprotection by augmenting the chaperone capacity and the degradation of polyubiquitylated substrates against proteostatic impairments. Further, the druggable Ranbp2 CY holds pan-therapeutic potential against proteotoxicity and neurodegeneration.
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Affiliation(s)
- Hemangi Patil
- Department of Ophthalmology Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Haiqing Yi
- Department of Ophthalmology Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Kyoung-In Cho
- Department of Ophthalmology Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Paulo A Ferreira
- Department of Ophthalmology Duke University Medical Center, Durham, North Carolina 27710, United States
- Department of Pathology Duke University Medical Center, Durham, North Carolina 27710, United States
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2
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Rubio AJ, Bencomo-Alvarez AE, Young JE, Velazquez VV, Lara JJ, Gonzalez MA, Eiring AM. 26S Proteasome Non-ATPase Regulatory Subunits 1 (PSMD1) and 3 (PSMD3) as Putative Targets for Cancer Prognosis and Therapy. Cells 2021; 10:2390. [PMID: 34572038 PMCID: PMC8472613 DOI: 10.3390/cells10092390] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 08/20/2021] [Accepted: 09/08/2021] [Indexed: 12/30/2022] Open
Abstract
Ever since the ubiquitin proteasome system was characterized, efforts have been made to manipulate its function to abrogate the progression of cancer. As a result, the anti-cancer drugs bortezomib, carfilzomib, and ixazomib targeting the 26S proteasome were developed to treat multiple myeloma, mantle cell lymphoma, and diffuse large B-cell lymphoma, among others. Despite success, adverse side effects and drug resistance are prominent, raising the need for alternative therapeutic options. We recently demonstrated that knockdown of the 19S regulatory components, 26S proteasome non-ATPase subunits 1 (PSMD1) and 3 (PSMD3), resulted in increased apoptosis of chronic myeloid leukemia (CML) cells, but had no effect on normal controls, suggesting they may be good targets for therapy. Therefore, we hypothesized that PSMD1 and PSMD3 are potential targets for anti-cancer therapeutics and that their relevance stretches beyond CML to other types of cancers. In the present study, we analyzed PSMD1 and PSMD3 mRNA and protein expression in cancerous tissue versus normal controls using data from The Cancer Genome Atlas (TCGA) and the Clinical Proteomic Tumor Analysis Consortium (CPTAC), comparing expression with overall survival. Altogether, our data suggest that PSMD1 and PSMD3 may be novel putative targets for cancer prognosis and therapy that are worthy of future investigation.
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Affiliation(s)
- Andres J Rubio
- Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center at El Paso, El Paso, TX 79905, USA
| | - Alfonso E Bencomo-Alvarez
- Center of Emphasis in Cancer, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center at El Paso, El Paso, TX 79905, USA
| | - James E Young
- Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center at El Paso, El Paso, TX 79905, USA
| | - Vanessa V Velazquez
- Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center at El Paso, El Paso, TX 79905, USA
| | - Joshua J Lara
- Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center at El Paso, El Paso, TX 79905, USA
| | - Mayra A Gonzalez
- Center of Emphasis in Cancer, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center at El Paso, El Paso, TX 79905, USA
| | - Anna M Eiring
- Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center at El Paso, El Paso, TX 79905, USA
- Center of Emphasis in Cancer, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center at El Paso, El Paso, TX 79905, USA
- Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center at El Paso, El Paso, TX 79905, USA
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3
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Chen X, Htet ZM, López-Alfonzo E, Martin A, Walters KJ. Proteasome interaction with ubiquitinated substrates: from mechanisms to therapies. FEBS J 2021; 288:5231-5251. [PMID: 33211406 PMCID: PMC8131406 DOI: 10.1111/febs.15638] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/10/2020] [Accepted: 11/17/2020] [Indexed: 12/11/2022]
Abstract
The 26S proteasome is responsible for regulated proteolysis in eukaryotic cells. Its substrates are diverse in structure, function, sequence length, and amino acid composition, and are targeted to the proteasome by post-translational modification with ubiquitin. Ubiquitination occurs through a complex enzymatic cascade and can also signal for other cellular events, unrelated to proteasome-catalyzed degradation. Like other post-translational protein modifications, ubiquitination is reversible, with ubiquitin chain hydrolysis catalyzed by the action of deubiquitinating enzymes (DUBs), ~ 90 of which exist in humans and allow for temporal events and dynamic ubiquitin-chain remodeling. DUBs have been known for decades to be an integral part of the proteasome, as deubiquitination is coupled to substrate unfolding and translocation into the internal degradation chamber. Moreover, the proteasome also binds several ubiquitinating enzymes and shuttle factors that recruit ubiquitinated substrates. The role of this intricate machinery and how ubiquitinated substrates interact with proteasomes remains an area of active investigation. Here, we review what has been learned about the mechanisms used by the proteasome to bind ubiquitinated substrates, substrate shuttle factors, ubiquitination machinery, and DUBs. We also discuss many open questions that require further study or the development of innovative approaches to be answered. Finally, we address the promise of expanded therapeutic targeting that could benefit from such new discoveries.
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Affiliation(s)
- Xiang Chen
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Zaw Min Htet
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California at Berkeley, CA, USA
| | - Erika López-Alfonzo
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California at Berkeley, CA, USA
| | - Andreas Martin
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California at Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California at Berkeley, CA, USA
| | - Kylie J Walters
- Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
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Račková L, Csekes E. Proteasome Biology: Chemistry and Bioengineering Insights. Polymers (Basel) 2020; 12:E2909. [PMID: 33291646 PMCID: PMC7761984 DOI: 10.3390/polym12122909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 12/12/2022] Open
Abstract
Proteasomal degradation provides the crucial machinery for maintaining cellular proteostasis. The biological origins of modulation or impairment of the function of proteasomal complexes may include changes in gene expression of their subunits, ubiquitin mutation, or indirect mechanisms arising from the overall impairment of proteostasis. However, changes in the physico-chemical characteristics of the cellular environment might also meaningfully contribute to altered performance. This review summarizes the effects of physicochemical factors in the cell, such as pH, temperature fluctuations, and reactions with the products of oxidative metabolism, on the function of the proteasome. Furthermore, evidence of the direct interaction of proteasomal complexes with protein aggregates is compared against the knowledge obtained from immobilization biotechnologies. In this regard, factors such as the structures of the natural polymeric scaffolds in the cells, their content of reactive groups or the sequestration of metal ions, and processes at the interface, are discussed here with regard to their influences on proteasomal function.
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Affiliation(s)
- Lucia Račková
- Centre of Experimental Medicine, Institute of Experimental Pharmacology and Toxicology, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia;
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5
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Khan SA, He J, Deng S, Zhang H, Liu G, Li S, Tang D, Zhang J, Shu Y, Wu H. Integrated analysis of mRNA and miRNA expression profiles reveals muscle growth differences between fast- and slow-growing king ratsnakes (Elaphe carinata). Comp Biochem Physiol B Biochem Mol Biol 2020; 248-249:110482. [DOI: 10.1016/j.cbpb.2020.110482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 06/18/2020] [Accepted: 07/20/2020] [Indexed: 10/23/2022]
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Xiong W, Wang W, Huang H, Jiang Y, Guo W, Liu H, Yu J, Hu Y, Wan J, Li G. Prognostic Significance of PSMD1 Expression in Patients with Gastric Cancer. J Cancer 2019; 10:4357-4367. [PMID: 31413756 PMCID: PMC6691719 DOI: 10.7150/jca.31543] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 05/21/2019] [Indexed: 12/28/2022] Open
Abstract
Background: PSMD1 has been considered to be involved in many human cancers, but its prognostic significance in gastric cancer (GC) has not been elucidated. The aim of this study was to evaluate the prognostic value of PSMD1 expression in tumor tissues of GC patients. Methods: We retrospectively analyzed the expression of PSMD1 in 241 paraffin-embedded GC specimens of the training cohort by immunohistochemistry. The prognostic value of PSMD1 expression was assessed using Kaplan-Meier survival curves and multivariate COX regression models. PSMD1 expression and other GC-associated risk factors were used to generate two nomograms to evaluate prognosis, and the performance of the two nomograms was assessed with respect to its calibration, discrimination, and clinical usefulness. Further validation was performed using an independent cohort of 170 cases. Results: High PSMD1 expression was significantly associated with decreased disease-free survival (DFS) and overall survival (OS) in GC patients. Furthermore, multivariate Cox proportional hazard analysis demonstrated that PSMD1 was an independent prognostic factor for DFS and OS. The two nomograms that were developed by integrating PSMD1 expression and the TNM staging system showed better prediction of DFS and OS than TNM staging system alone(C-index for training cohort: 0.708 (95% CI:0.670-0.746) and 0.712 (0.671-0.752), respectively; C-index for validation cohort: 0.704 (0.651-0.757) and 0.711 (0.656-0.767), respectively). Decision curve analysis demonstrated that the nomograms showed potential for clinical use. Conclusion: Intratumoral PSMD1 expression is a novel independent predictor of DFS and OS in GC patients. In the future, large-scale prospective studies will be necessary to confirm our findings regarding its potential prognostic and therapeutic value for GC patients.
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Affiliation(s)
- Wenjun Xiong
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, China.,Department of Gastrointestinal Surgery, Guangdong Provincial Hospital of Chinese Medicine, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wei Wang
- Department of Gastrointestinal Surgery, Guangdong Provincial Hospital of Chinese Medicine, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Haipeng Huang
- Department of Gastrointestinal Surgery, Guangdong Provincial Hospital of Chinese Medicine, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yuming Jiang
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, China
| | - Weihong Guo
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, China
| | - Hao Liu
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, China
| | - Jiang Yu
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, China
| | - Yanfeng Hu
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, China
| | - Jin Wan
- Department of Gastrointestinal Surgery, Guangdong Provincial Hospital of Chinese Medicine, the Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Guoxin Li
- Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangdong Provincial Engineering Technology Research Center of Minimally Invasive Surgery, Guangzhou, China
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Cai CZ, Zhou HF, Yuan NN, Wu MY, Lee SMY, Ren JY, Su HX, Lu JJ, Chen XP, Li M, Tan JQ, Lu JH. Natural alkaloid harmine promotes degradation of alpha-synuclein via PKA-mediated ubiquitin-proteasome system activation. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2019; 61:152842. [PMID: 31048127 DOI: 10.1016/j.phymed.2019.152842] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/17/2019] [Accepted: 01/25/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Parkinson's disease (PD) is an age-dependent progressive movement disorder characterized by a profound and selective loss of nigrostriatal dopaminergic neurons. Accumulation of <alpha>-synuclein (<alpha>-syn) positive protein aggregates in the substantia nigra is a pathological hallmark of PD, indicating that protein turnover defect is implicated in PD pathogenesis. PURPOSE This study aims to identify neuroprotective compounds which can alleviate the accumulation of <alpha>-syn in neuronal cells and dissect the underlying mechanisms. METHODS High throughput screening was performed by dot blot assay. The degradation of different forms of <alpha>-syn by candidate compounds were assessed by western blot. The autophagy lysosome pathway and ubiquitin-proteasome system were examined to dissect the degradation pathway. The UPS activity was assessed by cellular UPS substrates degradation assay and biochemical proteasome activity assay. Q-PCR was performed to test the mRNA level of different proteasome subunits. Furthermore, Neuroprotective effect of candidate compound was tested by LDH assay and PI staining. RESULTS Through the high throughput screening, harmine was identified as a potent <alpha>-syn lowering compound. The time-dependent and dose-dependent effects of harmine on the degradation of different forms of <alpha>-syn were further confirmed. Harmine could dramatically promote the degradation of UPS substrates GFP-CL1, Ub-R-GFP and Ub-G76V-GFP, and activate cellular proteasome activity. Mechanistically, harmine dramatically enhanced PKA phosphorylation to enhance proteasome subunit PSMD1 expression. PKA inhibitor blocked the effects of harmine in activating UPS, up regulating PSMD1 and promoting <alpha>-syn degradation, indicating that harmine enhances UPS function via PKA activation. Moreover, harmine efficiently rescued cell death induced by over-expression of <alpha>-syn, via UPS-dependent manner. CONCLUSION Harmine, as a new proteasome enhancer, may have potential to be developed into therapeutic agent against neurodegenerative diseases associated with UPS dysfunction and aberrant proteins accumulation.
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Affiliation(s)
- Cui-Zan Cai
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao SAR, China
| | - He-Feng Zhou
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao SAR, China
| | - Ning-Ning Yuan
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao SAR, China
| | - Ming-Yue Wu
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao SAR, China
| | - Simon Ming-Yuen Lee
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao SAR, China
| | - Jiao-Yan Ren
- School of Food Science and Engineering, South China University of Technology, Wushan RD., Tianhe District, Guangzhou, China
| | - Huan-Xing Su
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao SAR, China
| | - Jin-Jian Lu
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao SAR, China
| | - Xiu-Ping Chen
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao SAR, China
| | - Min Li
- Mr. and Mrs. Ko Chi Ming Centre for Parkinson's Disease Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong SAR, China
| | - Jie-Qiong Tan
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China.
| | - Jia-Hong Lu
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao SAR, China.
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VanderLinden RT, Hemmis CW, Yao T, Robinson H, Hill CP. Structure and energetics of pairwise interactions between proteasome subunits RPN2, RPN13, and ubiquitin clarify a substrate recruitment mechanism. J Biol Chem 2017; 292:9493-9504. [PMID: 28442575 DOI: 10.1074/jbc.m117.785287] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 04/24/2017] [Indexed: 11/06/2022] Open
Abstract
The 26S proteasome is a large cellular assembly that mediates the selective degradation of proteins in the nucleus and cytosol and is an established target for anticancer therapeutics. Protein substrates are typically targeted to the proteasome through modification with a polyubiquitin chain, which can be recognized by several proteasome-associated ubiquitin receptors. One of these receptors, RPN13/ADRM1, is recruited to the proteasome through direct interaction with the large scaffolding protein RPN2 within the 19S regulatory particle. To better understand the interactions between RPN13, RPN2, and ubiquitin, we used human proteins to map the RPN13-binding epitope to the C-terminal 14 residues of RPN2, which, like ubiquitin, binds the N-terminal pleckstrin-like receptor of ubiquitin (PRU) domain of RPN13. We also report the crystal structures of the RPN13 PRU domain in complex with peptides corresponding to the RPN2 C terminus and ubiquitin. Through mutational analysis, we validated the RPN2-binding interface revealed by our structures and quantified binding interactions with surface plasmon resonance and fluorescence polarization. In contrast to a previous report, we find that RPN13 binds ubiquitin with an affinity similar to that of other proteasome-associated ubiquitin receptors and that RPN2, ubiquitin, and the deubiquitylase UCH37 bind to RPN13 with independent energetics. These findings provide a detailed characterization of interactions that are important for proteasome function, indicate ubiquitin affinities that are consistent with the role of RPN13 as a proteasomal ubiquitin receptor, and have major implications for the development of novel anticancer therapeutics.
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Affiliation(s)
- Ryan T VanderLinden
- From the Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112
| | - Casey W Hemmis
- From the Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112
| | - Tingting Yao
- the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523, and
| | - Howard Robinson
- the Biology Department, Brookhaven National Laboratory, Upton, New York 11973
| | - Christopher P Hill
- From the Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112,
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9
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Voutsadakis IA. Proteasome expression and activity in cancer and cancer stem cells. Tumour Biol 2017; 39:101042831769224. [DOI: 10.1177/1010428317692248] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Abstract
Proteasome is a multi-protein organelle that participates in cellular proteostasis by destroying damaged or short-lived proteins in an organized manner guided by the ubiquitination signal. By being in a central place in the cellular protein complement homeostasis, proteasome is involved in virtually all cell processes including decisions on cell survival or death, cell cycle, and differentiation. These processes are important also in cancer, and thus, the proteasome is an important regulator of carcinogenesis. Cancers include a variety of cells which, according to the cancer stem cell theory, descend from a small percentage of cancer stem cells, alternatively termed tumor-initiating cells. These cells constitute the subsets that have the ability to propagate the whole variety of cancer and repopulate tumors after cytostatic therapies. Proteasome plays a role in cellular processes in cancer stem cells, but it has been found to have a decreased function in them compared to the rest of cancer cells. This article will discuss the transcriptional regulation of proteasome sub-unit proteins in cancer and in particular cancer stem cells and the relationship of the proteasome with the pluripotency that is the defining characteristic of stem cells. Therapeutic opportunities that present from the understanding of the proteasome role will also be discussed.
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Affiliation(s)
- Ioannis A Voutsadakis
- Division of Medical Oncology, Department of Internal Medicine, Sault Area Hospital, Sault Ste. Marie, ON, Canada
- Division of Clinical Sciences, Northern Ontario School of Medicine, Sudbury, ON, Canada
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10
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Abstract
Small ubiquitin-like modifiers (SUMOs) are essential for the regulation of several cellular processes and are potential therapeutic targets owing to their involvement in diseases such as cancer and Alzheimer disease. In the past decade, we have witnessed a rapid expansion of proteomic approaches for identifying sumoylated proteins, with recent advances in detecting site-specific sumoylation. In this Analysis, we combined all human SUMO proteomics data currently available into one cohesive database. We provide proteomic evidence for sumoylation of 3,617 proteins at 7,327 sumoylation sites, and insight into SUMO group modification by clustering the sumoylated proteins into functional networks. The data support sumoylation being a frequent protein modification (on par with other major protein modifications) with multiple nuclear functions, including in transcription, mRNA processing, DNA replication and the DNA-damage response.
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11
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Abstract
SUMOylation is a ubiquitin-related transient posttranslational modification pathway catalyzing the conjugation of small ubiquitin-like modifier (SUMO) proteins (SUMO1, SUMO2, and SUMO3) to lysine residues of proteins. SUMOylation targets a wide variety of cellular regulators and thereby affects a multitude of different cellular processes. SUMO/sentrin-specific proteases are able to remove SUMOs from targets, contributing to a tight control of SUMOylated proteins. Genetic and cell biological experiments indicate a critical role of balanced SUMOylation/deSUMOylation for proper cardiac development, metabolism, and stress adaptation. Here, we review the current knowledge about SUMOylation/deSUMOylation in the heart and provide an integrated picture of cardiac functions of the SUMO system under physiologic or pathologic conditions. We also describe potential therapeutic approaches targeting the SUMO machinery to combat heart disease.
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Affiliation(s)
- Luca Mendler
- From the Institute of Biochemistry II, Goethe University, Medical School, Frankfurt, Germany (L.M., S.M.); Institute of Biochemistry, Faculty of General Medicine, University of Szeged, Szeged, Hungary (L.M.); and Department I - Cardiac Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.)
| | - Thomas Braun
- From the Institute of Biochemistry II, Goethe University, Medical School, Frankfurt, Germany (L.M., S.M.); Institute of Biochemistry, Faculty of General Medicine, University of Szeged, Szeged, Hungary (L.M.); and Department I - Cardiac Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.).
| | - Stefan Müller
- From the Institute of Biochemistry II, Goethe University, Medical School, Frankfurt, Germany (L.M., S.M.); Institute of Biochemistry, Faculty of General Medicine, University of Szeged, Szeged, Hungary (L.M.); and Department I - Cardiac Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.).
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Randles L, Anchoori RK, Roden RBS, Walters KJ. The Proteasome Ubiquitin Receptor hRpn13 and Its Interacting Deubiquitinating Enzyme Uch37 Are Required for Proper Cell Cycle Progression. J Biol Chem 2016; 291:8773-83. [PMID: 26907685 DOI: 10.1074/jbc.m115.694588] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Indexed: 11/06/2022] Open
Abstract
Recently, we reported that bisbenzylidine piperidone RA190 adducts to Cys-88 of the proteasome ubiquitin receptor hRpn13, triggering accumulation of ubiquitinated proteins and endoplasmic reticulum stress-related apoptosis in various cancer cell lines. hRpn13 contains an N-terminal pleckstrin-like receptor for ubiquitin domain that binds ubiquitin and docks it into the proteasome as well as a C-terminal deubiquitinase adaptor (DEUBAD) domain that binds the deubiquitinating enzyme Uch37. Here we report that hRpn13 and Uch37 are required for proper cell cycle progression and that their protein knockdown leads to stalling at G0/G1 Moreover, serum-starved cells display reduced hRpn13 and Uch37 protein levels with hallmarks of G0/G1 stalling and recovery to their steady-state protein levels following release from nutrient deprivation. Interestingly, loss of hRpn13 correlates with a small but statistically significant reduction in Uch37 protein levels, suggesting that hRpn13 interaction may stabilize this deubiquitinating enzyme in human cells. We also find that RA190 treatment leads to a loss of S phase, suggesting a block of DNA replication, and G2 arrest by using fluorescence-activated cell sorting. Uch37 deprivation further indicated a reduction of DNA replication and G0/G1 stalling. Overall, this work implicates hRpn13 and Uch37 in cell cycle progression, providing a rationale for their function in cellular proliferation and for the apoptotic effect of the hRpn13-targeting molecule RA190.
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Affiliation(s)
- Leah Randles
- From the Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland 21702 and
| | | | - Richard B S Roden
- the Departments of Oncology, Pathology, and Gynecology and Obstetrics, The Johns Hopkins University, Baltimore, Maryland 21231
| | - Kylie J Walters
- From the Protein Processing Section, Structural Biophysics Laboratory, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland 21702 and
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13
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Cho KI, Haney V, Yoon D, Hao Y, Ferreira PA. Uncoupling phototoxicity-elicited neural dysmorphology and death by insidious function and selective impairment of Ran-binding protein 2 (Ranbp2). FEBS Lett 2015; 589:3959-68. [PMID: 26632511 DOI: 10.1016/j.febslet.2015.11.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 11/06/2015] [Accepted: 11/20/2015] [Indexed: 01/27/2023]
Abstract
Morphological disintegration of neurons is coupled invariably to neural death. In particular, disruption of outer segments of photoreceptor neurons triggers photoreceptor death regardless of the pathological stressors. We show that Ranbp2(-/-)::Tg-Ranbp2(CLDm-HA) mice with mutations in SUMO-binding motif (SBM) of cyclophilin-like domain (CLD) of Ran-binding protein 2 (Ranbp2) expressed in a null Ranbp2 background lack untoward effects in photoreceptors in the absence of light-stress. However, compared to wild type photoreceptors, light-stress elicits profound disintegration of outer segments of Ranbp2(-/-)::Tg-Ranbp2(CLDm-HA) with paradoxical age-dependent resistance of photoreceptors to death and genotype-independent activation of caspases. Ranbp2(-/-)::Tg-Ranbp2(CLDm-HA) exhibit photoreceptor death-independent changes in ubiquitin-proteasome system (UPS), but death-dependent increase of ubiquitin carrier protein 9(ubc9) levels. Hence, insidious functional impairment of SBM of Ranbp2's CLD promotes neuroprotection and uncoupling of photoreceptor degeneration and death against phototoxicity.
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Affiliation(s)
- Kyoung-in Cho
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, United States
| | - Victoria Haney
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, United States
| | - Dosuk Yoon
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, United States
| | - Yin Hao
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, United States
| | - Paulo A Ferreira
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27710, United States; Department of Pathology, Duke University Medical Center, Durham, NC 27710, United States.
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