1
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Pore SK, Ganguly A, Sau S, Godeshala S, Kanugula AK, Ummanni R, Kotamraju S, Banerjee R. N-end rule pathway inhibitor sensitizes cancer cells to antineoplastic agents by regulating XIAP and RAD21 protein expression. J Cell Biochem 2019; 121:804-815. [PMID: 31407360 DOI: 10.1002/jcb.29326] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/15/2019] [Indexed: 12/20/2022]
Abstract
Anticancer drugs exert their effects on cancer cells by deregulating many pathways linked to cell cycle, apoptosis, etc. but cancer cells gradually become resistive against anticancer drugs, thereby necessitating the development of newer generation anticancer molecules. N-end rule pathway has been shown to be involved in the degradation of many cell cycle and apoptosis-related proteins. However, the involvements of this pathway in cancer are not well established. Recently, we developed a non-peptide-based N-end rule pathway inhibitor, RF-C11 for type 1 and 2 recognition domains of E3 ubiquitin ligases. The inhibitor significantly increased the half-life of potential N-degrons leading to significant physiological changes in vivo. We hypothesized RF-C11 may be used to decipher the N-end rule pathway's role in cancer towards the development of anticancer therapeutics. In this study, we showed that RF-C11, barring noncancer cells, significantly sensitizes cancer cells towards different anticancer agents tested. We further find that the profound cellular sensitization to anticancer drugs was affected by (a) downregulation of X-linked inhibitor of apoptosis protein, an antiapoptotic protein and (b) by stabilization of RAD21, and thereby inhibiting metaphase to anaphase promotion. The study shows that RF-C11 or its analogs may be used as a novel additive in combination therapy against cancer.
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Affiliation(s)
- Subrata K Pore
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad, India.,Life Science Division, Institute of Advanced Study in Science and Technology, Guwahati, Assam, India
| | - Anirban Ganguly
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad, India
| | - Samaresh Sau
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan
| | - Sudhakar Godeshala
- Department of Chemical Engineering, Arizona State University, Tempe, Arizona
| | - Anantha K Kanugula
- Department of Integrative Medical Sciences, Northeast Ohio Medical University (NEOMED), Rootstown, Ohio
| | - Ramesh Ummanni
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad, India
| | - Srigiridhar Kotamraju
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad, India
| | - Rajkumar Banerjee
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad, India
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2
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Alqinyah M, Hooks SB. Regulating the regulators: Epigenetic, transcriptional, and post-translational regulation of RGS proteins. Cell Signal 2017; 42:77-87. [PMID: 29042285 DOI: 10.1016/j.cellsig.2017.10.007] [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: 08/01/2017] [Revised: 10/06/2017] [Accepted: 10/13/2017] [Indexed: 12/11/2022]
Abstract
Regulators of G protein signaling (RGS) are a family of proteins classically known to accelerate the intrinsic GTPase activity of G proteins, which results in accelerated inactivation of heterotrimeric G proteins and inhibition of G protein coupled receptor signaling. RGS proteins play major roles in essential cellular processes, and dysregulation of RGS protein expression is implicated in multiple diseases, including cancer, cardiovascular and neurodegenerative diseases. The expression of RGS proteins is highly dynamic and is regulated by epigenetic, transcriptional and post-translational mechanisms. This review summarizes studies that report dysregulation of RGS protein expression in disease states, and presents examples of drugs that regulate RGS protein expression. Additionally, this review discusses, in detail, the transcriptional and post-transcriptional mechanisms regulating RGS protein expression, and further assesses the therapeutic potential of targeting these mechanisms. Understanding the molecular mechanisms controlling the expression of RGS proteins is essential for the development of therapeutics that indirectly modulate G protein signaling by regulating expression of RGS proteins.
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Affiliation(s)
- Mohammed Alqinyah
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA
| | - Shelley B Hooks
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia, Athens, GA, USA.
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3
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Muñoz-Escobar J, Matta-Camacho E, Cho C, Kozlov G, Gehring K. Bound Waters Mediate Binding of Diverse Substrates to a Ubiquitin Ligase. Structure 2017; 25:719-729.e3. [PMID: 28392261 DOI: 10.1016/j.str.2017.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 02/03/2017] [Accepted: 03/09/2017] [Indexed: 11/16/2022]
Abstract
The N-end rule pathway controls the half-life of proteins based on their N-terminal residue. Positively charged type 1 N-degrons are recognized by a negatively charged pocket on the Zn finger named the UBR box. Here, we show that the UBR box is rigid, but bound water molecules in the pocket provide the structural plasticity required to bind different positively charged amino acids. Ultra-high-resolution crystal structures of arginine, histidine, and methylated arginine reveal that water molecules mediate the binding of N-degron peptides. Using a high-throughput binding assay and isothermal titration calorimetry, we demonstrate that the UBR box is able to bind methylated arginine and lysine peptides with high affinity and measure the preference for hydrophobic residues in the second position in the N-degron peptide. Finally, we show that the V122L mutation present in Johanson-Blizzard syndrome patients changes the specificity for the second position due to occlusion of the secondary pocket.
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Affiliation(s)
- Juliana Muñoz-Escobar
- Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC H3G 0B1, Canada
| | - Edna Matta-Camacho
- Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC H3G 0B1, Canada
| | - Cordelia Cho
- Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC H3G 0B1, Canada
| | - Guennadi Kozlov
- Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC H3G 0B1, Canada
| | - Kalle Gehring
- Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC H3G 0B1, Canada.
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4
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Shin SK, Kim JH, Lee JH, Son YH, Lee MW, Kim HJ, Noh SA, Kim KP, Kim IG, Lee MJ. Docosahexaenoic acid-mediated protein aggregates may reduce proteasome activity and delay myotube degradation during muscle atrophy in vitro. Exp Mol Med 2017; 49:e287. [PMID: 28104914 PMCID: PMC5291838 DOI: 10.1038/emm.2016.133] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 09/05/2016] [Accepted: 09/19/2016] [Indexed: 12/26/2022] Open
Abstract
Proteasomes are the primary degradation machinery for oxidatively damaged proteins that compose a class of misfolded protein substrates. Cellular levels of reactive oxygen species increase with age and this cellular propensity is particularly harmful when combined with the age-associated development of various human disorders including cancer, neurodegenerative disease and muscle atrophy. Proteasome activity is reportedly downregulated in these disease conditions. Herein, we report that docosahexaenoic acid (DHA), a major dietary omega-3 polyunsaturated fatty acid, mediates intermolecular protein cross-linkages through oxidation, and the resulting protein aggregates potently reduce proteasomal activity both in vitro and in cultured cells. Cellular models overexpressing aggregation-prone proteins such as tau showed significantly elevated levels of tau aggregates and total ubiquitin conjugates in the presence of DHA, thereby reflecting suppressed proteasome activity. Strong synergetic cytotoxicity was observed when the cells overexpressing tau were simultaneously treated with DHA. Antioxidant N-acetyl cysteine significantly desensitized the cells to DHA-induced oxidative stress. DHA significantly delayed the proteasomal degradation of muscle proteins in a cellular atrophy model. Thus, the results of our study identified DHA as a potent inducer of cellular protein aggregates that inhibit proteasome activity and potentially delay systemic muscle protein degradation in certain pathologic conditions.
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Affiliation(s)
- Seung Kyun Shin
- Department of Applied Chemistry, College of Applied Sciences, Kyung Hee University, Yongin, Korea
| | - Ji Hyeon Kim
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul, Korea
| | - Jung Hoon Lee
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea
| | - Young Hoon Son
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul, Korea.,Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea
| | - Min Wook Lee
- Department of Chemistry, College of Science, Korea University, Seoul, Korea
| | - Hak Joong Kim
- Department of Chemistry, College of Science, Korea University, Seoul, Korea
| | - Sue Ah Noh
- Department of Applied Chemistry, College of Applied Sciences, Kyung Hee University, Yongin, Korea
| | - Kwang Pyo Kim
- Department of Applied Chemistry, College of Applied Sciences, Kyung Hee University, Yongin, Korea
| | - In-Gyu Kim
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul, Korea.,Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea
| | - Min Jae Lee
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul, Korea.,Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea
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5
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Kim E, Kim S, Lee JH, Kwon YT, Lee MJ. Ablation of Arg-tRNA-protein transferases results in defective neural tube development. BMB Rep 2017; 49:443-8. [PMID: 27345715 PMCID: PMC5070732 DOI: 10.5483/bmbrep.2016.49.8.087] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Indexed: 12/05/2022] Open
Abstract
The arginylation branch of the N-end rule pathway is a ubiquitin-mediated
proteolytic system in which post-translational conjugation of Arg by
ATE1-encoded Arg-tRNA-protein transferase to N-terminal
Asp, Glu, or oxidized Cys residues generates essential degradation signals.
Here, we characterized the ATE1−/− mice
and identified the essential role of N-terminal arginylation in neural tube
development. ATE1-null mice showed severe intracerebral
hemorrhages and cystic space near the neural tubes. Expression of ATE1 was
prominent in the developing brain and spinal cord, and this pattern overlapped
with the migration path of neural stem cells. The
ATE1−/− brain showed defective
G-protein signaling. Finally, we observed reduced mitosis in
ATE1−/− neuroepithelium and a
significantly higher nitric oxide concentration in the
ATE1−/− brain. Our results strongly
suggest that the crucial role of ATE1 in neural tube development is directly
related to proper turn-over of the RGS4 protein, which participate in the
oxygen-sensing mechanism in the cells. [BMB Reports 2016; 49(8): 443-448]
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Affiliation(s)
- Eunkyoung Kim
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine; Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
| | - Seonmu Kim
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Jung Hoon Lee
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine; Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
| | - Yong Tae Kwon
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea
| | - Min Jae Lee
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine; Department of Biomedical Sciences, Seoul National University Graduate School; Neuroscience Research Institute, Seoul National University College of Medicine, Seoul 03080, Korea
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6
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Jiang Y, Lee J, Lee JH, Lee JW, Kim JH, Choi WH, Yoo YD, Cha-Molstad H, Kim BY, Kwon YT, Noh SA, Kim KP, Lee MJ. The arginylation branch of the N-end rule pathway positively regulates cellular autophagic flux and clearance of proteotoxic proteins. Autophagy 2016; 12:2197-2212. [PMID: 27560450 DOI: 10.1080/15548627.2016.1222991] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The N-terminal amino acid of a protein is an essential determinant of ubiquitination and subsequent proteasomal degradation in the N-end rule pathway. Using para-chloroamphetamine (PCA), a specific inhibitor of the arginylation branch of the pathway (Arg/N-end rule pathway), we identified that blocking the Arg/N-end rule pathway significantly impaired the fusion of autophagosomes with lysosomes. Under ER stress, ATE1-encoded Arg-tRNA-protein transferases carry out the N-terminal arginylation of the ER heat shock protein HSPA5 that initially targets cargo proteins, along with SQSTM1, to the autophagosome. At the late stage of autophagy, however, proteasomal degradation of arginylated HSPA5 might function as a critical checkpoint for the proper progression of autophagic flux in the cells. Consistently, the inhibition of the Arg/N-end rule pathway with PCA significantly elevated levels of MAPT and huntingtin aggregates, accompanied by increased numbers of LC3 and SQSTM1 puncta. Cells treated with the Arg/N-end rule inhibitor became more sensitized to proteotoxic stress-induced cytotoxicity. SILAC-based quantitative proteomics also revealed that PCA significantly alters various biological pathways, including cellular responses to stress, nutrient, and DNA damage, which are also closely involved in modulation of autophagic responses. Thus, our results indicate that the Arg/N-end rule pathway may function to actively protect cells from detrimental effects of cellular stresses, including proteotoxic protein accumulation, by positively regulating autophagic flux.
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Affiliation(s)
- Yanxialei Jiang
- a Department of Biochemistry and Molecular Biology , Seoul National University College of Medicine , Seoul , Korea
| | - Jeeyoung Lee
- a Department of Biochemistry and Molecular Biology , Seoul National University College of Medicine , Seoul , Korea.,b Department of Biomedical Sciences , Seoul National University Graduate School , Seoul , Korea
| | - Jung Hoon Lee
- a Department of Biochemistry and Molecular Biology , Seoul National University College of Medicine , Seoul , Korea.,b Department of Biomedical Sciences , Seoul National University Graduate School , Seoul , Korea
| | - Joon Won Lee
- d Department of Applied Chemistry , College of Applied Sciences, Kyung Hee University , Yongin , Korea
| | - Ji Hyeon Kim
- a Department of Biochemistry and Molecular Biology , Seoul National University College of Medicine , Seoul , Korea.,b Department of Biomedical Sciences , Seoul National University Graduate School , Seoul , Korea
| | - Won Hoon Choi
- a Department of Biochemistry and Molecular Biology , Seoul National University College of Medicine , Seoul , Korea.,b Department of Biomedical Sciences , Seoul National University Graduate School , Seoul , Korea
| | - Young Dong Yoo
- b Department of Biomedical Sciences , Seoul National University Graduate School , Seoul , Korea
| | - Hyunjoo Cha-Molstad
- c World Class Institute, Korea Research Institute of Bioscience and Biotechnology , Ochang, Cheongwon , Korea
| | - Bo Yeon Kim
- c World Class Institute, Korea Research Institute of Bioscience and Biotechnology , Ochang, Cheongwon , Korea
| | - Yong Tae Kwon
- b Department of Biomedical Sciences , Seoul National University Graduate School , Seoul , Korea
| | - Sue Ah Noh
- d Department of Applied Chemistry , College of Applied Sciences, Kyung Hee University , Yongin , Korea
| | - Kwang Pyo Kim
- d Department of Applied Chemistry , College of Applied Sciences, Kyung Hee University , Yongin , Korea
| | - Min Jae Lee
- a Department of Biochemistry and Molecular Biology , Seoul National University College of Medicine , Seoul , Korea.,b Department of Biomedical Sciences , Seoul National University Graduate School , Seoul , Korea
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7
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N-end rule pathway inhibition assists colon tumor regression via necroptosis. MOLECULAR THERAPY-ONCOLYTICS 2016; 3:16020. [PMID: 27556106 PMCID: PMC4980110 DOI: 10.1038/mto.2016.20] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Revised: 06/14/2016] [Accepted: 06/16/2016] [Indexed: 12/23/2022]
Abstract
Recent study has shown that N-end rule pathway, an ubiquitin dependent proteolytic system, counteracts cell death by degrading many antisurvival protein fragments like BCLxL, BRCA1, RIPK1, etc. Inhibition of the N-end rule pathway can lead to metabolic stabilization of proapoptotic protein fragments like RIPK1, thereby sensitizing cells to programmed cell death. Receptor interacting serine-threonine protein kinase-1 (RIPK1) is one of the upstream regulators of programmed necrosis known as necroptosis. Necroptosis is particularly gaining attention of cancer biologists as it provides an alternate therapeutic modality to kill cancer cells, which often evolve multiple strategies to circumvent growth inhibition by apoptosis. Utilizing the over expression of biotin receptor in cancer cells, herein, we report that coadministration of synthetic hetero-bivalent N-end rule inhibitor RFC11 and anticancer drug shikonin solubilized in a stable biotin receptor-targeted liposome exhibited significant synergistic antitumor effect in both subcutaneous and orthotopic mouse colon tumor model through induction of necroptosis with distinctive upregulation of RIPK1. Besides developing a newly targeted formulation for necroptosis induction, this report is the first in vivo evidence demonstrating that potent inhibition of N-end rule pathway can enhance therapeutic efficacy of conventional chemotherapeutics.
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8
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Kim JH, Kim E, Choi WH, Lee J, Lee JH, Lee H, Kim DE, Suh YH, Lee MJ. Inhibitory RNA Aptamers of Tau Oligomerization and Their Neuroprotective Roles against Proteotoxic Stress. Mol Pharm 2016; 13:2039-48. [PMID: 27120117 DOI: 10.1021/acs.molpharmaceut.6b00165] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Tau is a cytosolic protein that functions in the assembly and stabilization of axonal microtubule networks. Its oligomerization may be the rate-limiting step of insoluble aggregate formation, which is a neuropathological hallmark of Alzheimer's disease (AD) and a number of other tauopathies. Recent evidence indicates that soluble tau oligomers are the toxic species for tau-mediated pathology during AD progression. Herein, we describe novel RNA aptamers that target human tau and were identified through an in vitro selection process. These aptamers significantly inhibited the oligomerization propensity of tau both in vitro and in cultured cell models of tauopathy without affecting the half-life of tau. Tauopathy model cells treated with the aptamers were less sensitized to proteotoxic stress induced by tau overexpression. Moreover, the tau aptamers significantly alleviated synthetic tau oligomer-mediated neurotoxicity and dendritic spine loss in primary hippocampal neurons. Thus, our study demonstrates that delaying tau assembly with RNA aptamers is an effective strategy for protecting cells under various neurodegenerative stresses originating from pathogenic tau oligomerization.
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Affiliation(s)
- Ji Hyeon Kim
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine , Seoul 03080, Korea.,Department of Biomedical Sciences, Seoul National University Graduate School , Seoul 03080, Korea
| | - Eunkyoung Kim
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine , Seoul 03080, Korea
| | - Won Hoon Choi
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine , Seoul 03080, Korea.,Department of Biomedical Sciences, Seoul National University Graduate School , Seoul 03080, Korea
| | - Jeeyoung Lee
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine , Seoul 03080, Korea.,Department of Biomedical Sciences, Seoul National University Graduate School , Seoul 03080, Korea
| | - Jung Hoon Lee
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine , Seoul 03080, Korea
| | - Hyojin Lee
- Department of Biomedical Sciences, Seoul National University Graduate School , Seoul 03080, Korea.,Neuroscience Research Institute, Seoul National University College of Medicine , Seoul 03080, Korea
| | - Dong-Eun Kim
- Department of Bioscience and Biotechnology, Konkuk University , Seoul 05029, Korea
| | - Young Ho Suh
- Department of Biomedical Sciences, Seoul National University Graduate School , Seoul 03080, Korea.,Neuroscience Research Institute, Seoul National University College of Medicine , Seoul 03080, Korea
| | - Min Jae Lee
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine , Seoul 03080, Korea.,Department of Biomedical Sciences, Seoul National University Graduate School , Seoul 03080, Korea.,Biomedical Research Institutue, Seoul National University Hospital , Seoul 03080, Korea
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9
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Lee JH, Jiang Y, Kwon YT, Lee MJ. Pharmacological Modulation of the N-End Rule Pathway and Its Therapeutic Implications. Trends Pharmacol Sci 2015; 36:782-797. [PMID: 26434644 DOI: 10.1016/j.tips.2015.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/13/2015] [Accepted: 07/16/2015] [Indexed: 11/26/2022]
Abstract
The N-end rule pathway is a proteolytic system in which single N-terminal amino acids of short-lived substrates determine their metabolic half-lives. Substrates of this pathway have been implicated in the pathogenesis of many diseases, including malignancies, neurodegeneration, and cardiovascular disorders. This review provides a comprehensive overview of current knowledge about the mechanism and functions of the N-end rule pathway. Pharmacological strategies for the modulation of target substrate degradation are also reviewed, with emphasis on their in vivo implications. Given the rapid advances in structural and biochemical understanding of the recognition components (N-recognins) of the N-end rule pathway, small-molecule inhibitors and activating ligands of N-recognins emerge as therapeutic agents with novel mechanisms of action.
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Affiliation(s)
- Jung Hoon Lee
- Department of Biochemistry and Molecular Biology, Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea
| | - Yanxialei Jiang
- Department of Biochemistry and Molecular Biology, Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea
| | - Yong Tae Kwon
- Protein Metabolism Medical Research Center, Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea.
| | - Min Jae Lee
- Department of Biochemistry and Molecular Biology, Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea; Protein Metabolism Medical Research Center, Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea; Neuroscience Research Institute, Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea.
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10
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A neurostimulant para-chloroamphetamine inhibits the arginylation branch of the N-end rule pathway. Sci Rep 2014; 4:6344. [PMID: 25212999 PMCID: PMC4161967 DOI: 10.1038/srep06344] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 08/12/2014] [Indexed: 11/08/2022] Open
Abstract
In the arginylation branch of the N-end rule pathway, unacetylated N-terminal destabilizing residues function as essential determinants of protein degradation signals (N-degron). Here, we show that a neurostimulant, para-chloroamphetamine (PCA), specifically inhibits the Arg/N-end rule pathway, delaying the degradation of its artificial and physiological substrates, including regulators of G protein signaling 4 (RGS4), in vitro and in cultured cells. In silico computational analysis indicated that PCA strongly interacts with both UBR box and ClpS box, which bind to type 1 and type 2 N-degrons, respectively. Moreover, intraperitoneal injection of PCA significantly stabilized endogenous RGS4 proteins in the whole mouse brain and, particularly, in the frontal cortex and hippocampus. Consistent with the role of RGS4 in G protein signaling, treatment with PCA impaired the activations of GPCR downstream effectors in N2A cells, phenocopying ATE1-null mutants. In addition, levels of pathological C-terminal fragments of TDP43 bearing N-degrons (Arg208-TDP25) were significantly elevated in the presence of PCA. Thus, our study identifies PCA as a potential tool to understand and modulate various pathological processes regulated by the Arg/N-end rule pathway, including neurodegenerative processes in FTLD-U and ALS.
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