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McNeill SM, Zhao P. The roles of RGS proteins in cardiometabolic disease. Br J Pharmacol 2024; 181:2319-2337. [PMID: 36964984 DOI: 10.1111/bph.16076] [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: 09/21/2022] [Revised: 02/12/2023] [Accepted: 03/20/2023] [Indexed: 03/27/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are the most prominent receptors on the surface of the cell and play a central role in the regulation of cardiac and metabolic functions. GPCRs transmit extracellular stimuli to the interior of the cells by activating one or more heterotrimeric G proteins. The duration and intensity of G protein-mediated signalling are tightly controlled by a large array of intracellular mediators, including the regulator of G protein signalling (RGS) proteins. RGS proteins selectively promote the GTPase activity of a subset of Gα subunits, thus serving as negative regulators in a pathway-dependent manner. In the current review, we summarise the involvement of RGS proteins in cardiometabolic function with a focus on their tissue distribution, mechanisms of action and dysregulation under various disease conditions. We also discuss the potential therapeutic applications for targeting RGS proteins in treating cardiometabolic conditions and current progress in developing RGS modulators. LINKED ARTICLES: This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.
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Affiliation(s)
- Samantha M McNeill
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Peishen Zhao
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins (CCeMMP), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
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2
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Florke Gee RR, Huber AD, Wu J, Bajpai R, Loughran AJ, Pruett-Miller SM, Chen T. The F-box-only protein 44 regulates pregnane X receptor protein level by ubiquitination and degradation. Acta Pharm Sin B 2023; 13:4523-4534. [PMID: 37969738 PMCID: PMC10638512 DOI: 10.1016/j.apsb.2023.07.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/24/2023] [Accepted: 06/13/2023] [Indexed: 11/17/2023] Open
Abstract
Pregnane X receptor (PXR) is a ligand-activated nuclear receptor that transcriptionally upregulates drug-metabolizing enzymes [e.g., cytochrome P450 3A4 (CYP3A4)] and transporters. Although the regulation of PXR target genes is well-characterized, less is known about the regulation of PXR protein level. By screening an RNAi library, we identified the F-box-only protein 44 (FBXO44) as a novel E3 ligase for PXR. PXR abundance increases upon knockdown of FBXO44, and, inversely, decreases upon overexpression of FBXO44. Further analysis revealed that FBXO44 interacts with PXR, leading to its ubiquitination and proteasomal degradation, and we determined that the F-box associated domain of FBXO44 and the ligand binding domain of PXR are required for the functional interaction. In summary, FBXO44 regulates PXR protein abundance, which has downstream consequences for CYP3A4 levels and drug-drug interactions. The results of this study provide new insight into the molecular mechanisms that regulate PXR protein level and activity and suggest the importance of considering how modulating E3 ubiquitin ligase activities will affect PXR-mediated drug metabolism.
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Affiliation(s)
- Rebecca R. Florke Gee
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
- Graduate School of Biomedical Sciences, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Andrew D. Huber
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jing Wu
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Richa Bajpai
- Center for Advanced Genome Engineering and Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Allister J. Loughran
- Center for Advanced Genome Engineering and Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Shondra M. Pruett-Miller
- Center for Advanced Genome Engineering and Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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3
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Li L, Xu Q, Tang C. RGS proteins and their roles in cancer: friend or foe? Cancer Cell Int 2023; 23:81. [PMID: 37118788 PMCID: PMC10148553 DOI: 10.1186/s12935-023-02932-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 04/21/2023] [Indexed: 04/30/2023] Open
Abstract
As negative modulators of G-protein-coupled receptors (GPCRs) signaling, regulators of G protein signaling (RGS) proteins facilitate various downstream cellular signalings through regulating kinds of heterotrimeric G proteins by stimulating the guanosine triphosphatase (GTPase) activity of G-protein α (Gα) subunits. The expression of RGS proteins is dynamically and precisely mediated by several different mechanisms including epigenetic regulation, transcriptional regulation -and post-translational regulation. Emerging evidence has shown that RGS proteins act as important mediators in controlling essential cellular processes including cell proliferation, survival -and death via regulating downstream cellular signaling activities, indicating that RGS proteins are fundamentally involved in sustaining normal physiological functions and dysregulation of RGS proteins (such as aberrant expression of RGS proteins) is closely associated with pathologies of many diseases such as cancer. In this review, we summarize the molecular mechanisms governing the expression of RGS proteins, and further discuss the relationship of RGS proteins and cancer.
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Affiliation(s)
- Lin Li
- National Clinical Research Center for Child Health of the Children's Hospital, Zhejiang University School of Medicine, No. 3333, Binsheng Rd., Hangzhou, 310052, People's Republic of China
- Department of Urology, Third Affiliated Hospital of the Second Military Medical University, Shanghai, 201805, China
| | - Qiang Xu
- National Clinical Research Center for Child Health of the Children's Hospital, Zhejiang University School of Medicine, No. 3333, Binsheng Rd., Hangzhou, 310052, People's Republic of China
| | - Chao Tang
- National Clinical Research Center for Child Health of the Children's Hospital, Zhejiang University School of Medicine, No. 3333, Binsheng Rd., Hangzhou, 310052, People's Republic of China.
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Zhang Q, Sjögren B. Palmitoylation of RGS20 affects Gα o-mediated signaling independent of its GAP activity. Cell Signal 2023; 107:110682. [PMID: 37075876 DOI: 10.1016/j.cellsig.2023.110682] [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: 09/13/2022] [Revised: 04/07/2023] [Accepted: 04/15/2023] [Indexed: 04/21/2023]
Abstract
Regulator of protein signaling (RGS20) is a member of the RGS protein superfamily, which serve as key negative regulators of G protein-mediated signal transduction. Through their GTPase accelerating protein (GAP) activity, RGS proteins deactivate α-subunits of heterotrimeric G proteins. In addition, the majority of RGS proteins also have the ability to act through other, non-GAP related, functions. RGS20 is one of three members of the RZ subfamily, which all show selective GAP activity towards Gαz, however emerging data suggest that RGS20 can also regulate Gi/o-mediated signaling. While increased RGS20 expression is associated with the progression of multiple cancers, a large gap still exists relating to the mechanisms of RGS20 regulation and function. RGS20 contains a poly-cysteine string motif and a conserved cysteine in RGS domain, which are assumed to be palmitoylated. Palmitoylation, an important post-translational modification, plays an important role in cells by changing cellular functions of proteins. Consequently, the aim of this study was to confirm that RGS20 is palmitoylated and determine how palmitoylation affects its inhibition of Gαo-mediated signaling. We found a significant positive correlation between RGS20 palmitoylation and its association with active Gαo. We also showed that a conserved cysteine residue in the RGS domain is a critical site for its palmitoylation, with large impact on its association with Gαo. Palmitoylation on this site did not affect its GAP activity, however, it increased the inhibition of Gαo-mediated cAMP signaling. Altogether these data suggest that palmitoylation is a regulatory mechanism controlling RGS20 function, and that RGS20 can inhibit Gαo signaling through both GAP activity and non-GAP mechanisms.
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Affiliation(s)
- Qian Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, United States of America
| | - Benita Sjögren
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, United States of America.
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Roles of Cullin-RING Ubiquitin Ligases in Cardiovascular Diseases. Biomolecules 2022; 12:biom12030416. [PMID: 35327608 PMCID: PMC8946067 DOI: 10.3390/biom12030416] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 03/03/2022] [Accepted: 03/04/2022] [Indexed: 12/18/2022] Open
Abstract
Maintenance of protein homeostasis is crucial for virtually every aspect of eukaryotic biology. The ubiquitin-proteasome system (UPS) represents a highly regulated quality control machinery that protects cells from a variety of stress conditions as well as toxic proteins. A large body of evidence has shown that UPS dysfunction contributes to the pathogenesis of cardiovascular diseases. This review highlights the latest findings regarding the physiological and pathological roles of cullin-RING ubiquitin ligases (CRLs), an essential player in the UPS, in the cardiovascular system. To inspire potential therapeutic invention, factors regulating CRL activities are also discussed.
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Lin CZ, Liu ZQ, Zhou WK, Ji T, Cao W. Effect of the regulator of G-protein signaling 2 on the proliferation and invasion of oral squamous cell carcinoma cells and its molecular mechanism. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2021; 39:320-327. [PMID: 34041882 DOI: 10.7518/hxkq.2021.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVES This study aims to investigate the effect of the regulator of G-protein signaling 2 (RGS2) on the proliferation and invasion of oral squamous cell carcinoma (OSCC) cells and its potential molecular mechanism. Metho⁃ds The expression status and clinical significance of RGS2 in head and neck squamous cell carcinomas and matched adjacent normal tissues were evaluated using TCGA database. Three OSCC cell lines (i.e., SCC-9, Cal27, and Fadu) were overexpressed with RGS2, and the effect of RGS2 on cell proliferation and invasion was determined using the Transwell, clone formation, and cell counting kit (CCK)-8 assays. Moreover, the yeast two-hybrid scree-ning and co-immunoprecipitation (Co-IP) assays were conducted to detect the correlation of RGS2, four and a half LIM domains protein 1 (FHL1), and damage DNA-binding protein 1 (DDB1). RESULTS The expression level of RGS2 in OSCC was significantly lower than that in matched adjacent normal tissues (P=0.023). The high RGS2 expression level was negatively correlated with lymphovascular invasion (P<0.001). After transfection with lentiv-RGS2, the expression of RGS2 was increased, and the invasion and proliferation abilities of OSCC cell lines were evidently inhibited. FHL1 could competitively bind with RGS2, which decreased the integration of DDB1 and RGS2, inhibited the ubiquitination process of RGS2, and maintained the stability of the RGS2 protein. CONCLUSIONS RGS2 plays an important role in the inhibition of OSCC proliferation and invasion. The structure stability of RGS2 is competitively regulated by FHL1 and DDB1.
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Affiliation(s)
- Cheng-Zhong Lin
- The 2nd Dental Center, Ninth People,s Hospital, Shanghai Jiao Tong University School of Medicine; National Clinical Research Center for Oral Disease; Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai 200011, China
| | - Zhe-Qi Liu
- Dept. of Oral and Maxillofacial-Head and Neck Oncology, Ninth People,s Hospital, Shanghai Jiao Tong University, School of Medicine; National Clinical Research Center for Oral Disease; Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai 200011, China
| | - Wen-Kai Zhou
- Dept. of Oral and Maxillofacial-Head and Neck Oncology, Ninth People,s Hospital, Shanghai Jiao Tong University, School of Medicine; National Clinical Research Center for Oral Disease; Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai 200011, China
| | - Tong Ji
- Dept. of Oral and Maxillofacial-Head and Neck Oncology, Ninth People,s Hospital, Shanghai Jiao Tong University, School of Medicine; National Clinical Research Center for Oral Disease; Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai 200011, China
| | - Wei Cao
- Dept. of Oral and Maxillofacial-Head and Neck Oncology, Ninth People,s Hospital, Shanghai Jiao Tong University, School of Medicine; National Clinical Research Center for Oral Disease; Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Shanghai 200011, China
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7
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Gu Y, Ma X, Li J, Ma Y, Zhang Y. Identification of candidate targets for the diagnosis and treatment of atherosclerosis by bioinformatics analysis. Am J Transl Res 2021; 13:4137-4151. [PMID: 34150004 PMCID: PMC8205787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
Atherosclerosis, a chronic inflammatory disease, is the primary cause of most cardiovascular diseases. Circular RNAs (circRNAs) were reported to serve as post-transcriptional regulators and diagnostic markers in various diseases, but the underlying correlation between circRNAs and atherosclerosis remains elusive. In this study, we downloaded the microarray dataset GSE107522 from the Gene Expression Omnibus (GEO) and identified nine differentially expressed circRNAs (DECs). DECs expression in exosomes were investigated, and hsa_circ_0005699 was selected for subsequent analysis. We then identified 14 RNA-binding proteins (RBPs) and 71 possible hsa_circ_0005699-interacting microRNAs. Subsequently, target gene prediction and enrichment analyses were performed. The enriched pathways of RBP eIF4AIII include spliceosome, cell cycle, and pathways in cancer. We constructed a protein-protein interaction network, and 20 hub genes were identified using Search Tool for the Retrieval of Interacting Genes/Proteins and Cytoscape. Hub gene analysis revealed significant enrichment in mRNA splicing via the spliceosome, RNA splicing, protein binding, neurotrophin signaling pathway, and Ras signaling pathway. Using DrugMatrix of the Enrichr database, we identified 16 most significant small-molecule compounds that interacted with hub genes. Finally, seven hub genes (NEDD4L, FBXO44, FBXO27, WSB1, FBXW8, UBE2F, and ASB1) in cluster 1 were considered key targets associated with atherosclerosis according to MCODE analysis and the intersection between the module and hub genes. Thus, hsa_circ_0005699, RBP eIF4AIII, and the seven identified hub genes (NEDD4L, FBXO44, FBXO27, WSB1, FBXW8, UBE2F, and ASB1) could help to elucidate the pathogenesis and progression of atherosclerosis. This work may contribute to providing candidate targets for the diagnosis and treatment of atherosclerosis.
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Affiliation(s)
- Yan Gu
- Affiliated Hospital of Inner Mongolia Medical UniversityHohhot 010050, The Inner Mongolia Autonomous Region, P. R. China
| | - Xiao Ma
- Chinese People’s Liberation Army No. 969 HospitalHohhot 010051, The Inner Mongolia Autonomous Region, P. R. China
| | - Jing Li
- Affiliated Hospital of Inner Mongolia Medical UniversityHohhot 010050, The Inner Mongolia Autonomous Region, P. R. China
| | - Yuhong Ma
- Affiliated Hospital of Inner Mongolia Medical UniversityHohhot 010050, The Inner Mongolia Autonomous Region, P. R. China
| | - Yun Zhang
- Affiliated Hospital of Inner Mongolia Medical UniversityHohhot 010050, The Inner Mongolia Autonomous Region, P. R. China
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8
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Fuentes N, McCullough M, Panettieri RA, Druey KM. RGS proteins, GRKs, and beta-arrestins modulate G protein-mediated signaling pathways in asthma. Pharmacol Ther 2021; 223:107818. [PMID: 33600853 DOI: 10.1016/j.pharmthera.2021.107818] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/25/2021] [Indexed: 12/17/2022]
Abstract
Asthma is a highly prevalent disorder characterized by chronic lung inflammation and reversible airways obstruction. Pathophysiological features of asthma include episodic and reversible airway narrowing due to increased bronchial smooth muscle shortening in response to external and host-derived mediators, excessive mucus secretion into the airway lumen, and airway remodeling. The aberrant airway smooth muscle (ASM) phenotype observed in asthma manifests as increased sensitivity to contractile mediators (EC50) and an increase in the magnitude of contraction (Emax); collectively these attributes have been termed "airways hyper-responsiveness" (AHR). This defining feature of asthma can be promoted by environmental factors including airborne allergens, viruses, and air pollution and other irritants. AHR reduces airway caliber and obstructs airflow, evoking clinical symptoms such as cough, wheezing and shortness of breath. G-protein-coupled receptors (GPCRs) have a central function in asthma through their impact on ASM and airway inflammation. Many but not all treatments for asthma target GPCRs mediating ASM contraction or relaxation. Here we discuss the roles of specific GPCRs, G proteins, and their associated signaling pathways, in asthma, with an emphasis on endogenous mechanisms of GPCR regulation of ASM tone and lung inflammation including regulators of G-protein signaling (RGS) proteins, G-protein coupled receptor kinases (GRKs), and β-arrestin.
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Affiliation(s)
- Nathalie Fuentes
- Lung and Vascular Inflammation Section, Laboratory of Allergic Diseases, NIAID/NIH, Bethesda, MD, United States of America
| | - Morgan McCullough
- Lung and Vascular Inflammation Section, Laboratory of Allergic Diseases, NIAID/NIH, Bethesda, MD, United States of America
| | - Reynold A Panettieri
- Rutgers Institute for Translational Medicine and Science, Child Health Institute of New Jersey, Rutgers University School of Medicine, New Brunswick, NJ, United States of America
| | - Kirk M Druey
- Lung and Vascular Inflammation Section, Laboratory of Allergic Diseases, NIAID/NIH, Bethesda, MD, United States of America.
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9
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FBXO44 promotes DNA replication-coupled repetitive element silencing in cancer cells. Cell 2020; 184:352-369.e23. [PMID: 33357448 DOI: 10.1016/j.cell.2020.11.042] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 10/11/2020] [Accepted: 11/24/2020] [Indexed: 02/06/2023]
Abstract
Repetitive elements (REs) compose ∼50% of the human genome and are normally transcriptionally silenced, although the mechanism has remained elusive. Through an RNAi screen, we identified FBXO44 as an essential repressor of REs in cancer cells. FBXO44 bound H3K9me3-modified nucleosomes at the replication fork and recruited SUV39H1, CRL4, and Mi-2/NuRD to transcriptionally silence REs post-DNA replication. FBXO44/SUV39H1 inhibition reactivated REs, leading to DNA replication stress and stimulation of MAVS/STING antiviral pathways and interferon (IFN) signaling in cancer cells to promote decreased tumorigenicity, increased immunogenicity, and enhanced immunotherapy response. FBXO44 expression inversely correlated with replication stress, antiviral pathways, IFN signaling, and cytotoxic T cell infiltration in human cancers, while a FBXO44-immune gene signature correlated with improved immunotherapy response in cancer patients. FBXO44/SUV39H1 were dispensable in normal cells. Collectively, FBXO44/SUV39H1 are crucial repressors of RE transcription, and their inhibition selectively induces DNA replication stress and viral mimicry in cancer cells.
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10
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Blondelle J, Biju A, Lange S. The Role of Cullin-RING Ligases in Striated Muscle Development, Function, and Disease. Int J Mol Sci 2020; 21:E7936. [PMID: 33114658 PMCID: PMC7672578 DOI: 10.3390/ijms21217936] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/11/2020] [Accepted: 10/13/2020] [Indexed: 02/07/2023] Open
Abstract
The well-orchestrated turnover of proteins in cross-striated muscles is one of the fundamental processes required for muscle cell function and survival. Dysfunction of the intricate protein degradation machinery is often associated with development of cardiac and skeletal muscle myopathies. Most muscle proteins are degraded by the ubiquitin-proteasome system (UPS). The UPS involves a number of enzymes, including E3-ligases, which tightly control which protein substrates are marked for degradation by the proteasome. Recent data reveal that E3-ligases of the cullin family play more diverse and crucial roles in cross striated muscles than previously anticipated. This review highlights some of the findings on the multifaceted functions of cullin-RING E3-ligases, their substrate adapters, muscle protein substrates, and regulatory proteins, such as the Cop9 signalosome, for the development of cross striated muscles, and their roles in the etiology of myopathies.
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Affiliation(s)
- Jordan Blondelle
- Department of Medicine, University of California, La Jolla, CA 92093, USA
| | - Andrea Biju
- Department of Medicine, University of California, La Jolla, CA 92093, USA
| | - Stephan Lange
- Department of Medicine, University of California, La Jolla, CA 92093, USA
- Department of Molecular and Clinical Medicine, University of Gothenburg, 41345 Gothenburg, Sweden
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McNabb HJ, Gonzalez S, Muli CS, Sjögren B. N-Terminal Targeting of Regulator of G Protein Signaling Protein 2 for F-Box Only Protein 44-Mediated Proteasomal Degradation. Mol Pharmacol 2020; 98:677-685. [PMID: 33008920 DOI: 10.1124/molpharm.120.000061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 09/17/2020] [Indexed: 12/28/2022] Open
Abstract
Regulator of G protein signaling (RGS) proteins are negative modulators of G protein signaling that have emerged as promising drug targets to improve specificity and reduce side effects of G protein-coupled receptor-related therapies. Several small molecule RGS protein inhibitors have been identified; however, enhancing RGS protein function is often more clinically desirable but presents a challenge. Low protein levels of RGS2 are associated with various pathologies, including hypertension and heart failure. For this reason, RGS2 is a prominent example wherein enhancing its function would be beneficial. RGS2 is rapidly ubiquitinated and proteasomally degraded, providing a point of intervention for small molecule RGS2-stabilizing compounds. We previously identified a novel cullin-RING E3 ligase utilizing F-box only protein 44 (FBXO44) as the substrate recognition component. Here, we demonstrate that RGS2 associates with FBXO44 through a stretch of residues in its N terminus. RGS2 contains four methionine residues close to the N terminus that can act as alternative translation initiation sites. The shorter translation initiation variants display reduced ubiquitination and proteasomal degradation as a result of lost association with FBXO44. In addition, we show that phosphorylation of Ser3 may be an additional mechanism to protect RGS2 from FBXO44-mediated proteasomal degradation. These findings contribute to elucidating mechanisms regulating steady state levels of RGS2 protein and will inform future studies to develop small molecule RGS2 stabilizers. These would serve as novel leads in pathologies associated with low RGS2 protein levels, such as hypertension, heart failure, and anxiety. SIGNIFICANCE STATEMENT: E3 ligases provide a novel point of intervention for therapeutic development, but progress is hindered by the lack of available information about specific E3-substrate pairs. Here, we provide molecular detail on the recognition of regulator of G protein signaling protein 2 (RGS2) by its E3 ligase, increasing the potential for rational design of small molecule RGS2 protein stabilizers. These would be clinically useful in pathologies associated with low RGS2 protein levels, such as hypertension, heart failure, and anxiety.
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Affiliation(s)
- Harrison J McNabb
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Stephanie Gonzalez
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Christine S Muli
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Benita Sjögren
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
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12
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McNabb HJ, Zhang Q, Sjögren B. Emerging Roles for Regulator of G Protein Signaling 2 in (Patho)physiology. Mol Pharmacol 2020; 98:751-760. [PMID: 32973086 DOI: 10.1124/molpharm.120.000111] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 09/08/2020] [Indexed: 12/11/2022] Open
Abstract
Since their discovery in the mid-1990s, regulator of G protein signaling (RGS) proteins have emerged as key regulators of signaling through G protein-coupled receptors. Among the over 20 known RGS proteins, RGS2 has received increasing interest as a potential therapeutic drug target with broad clinical implications. RGS2 is a member of the R4 subfamily of RGS proteins and is unique in that it is selective for Gα q Despite only having an RGS domain, responsible for the canonical GTPase activating protein activity, RGS2 can regulate additional processes, such as protein synthesis and adenylate cyclase activity, through protein-protein interactions. Here we provide an update of the current knowledge of RGS2 function as it relates to molecular mechanisms of regulation as well as its potential role in regulating a number of physiologic systems and pathologies, including cardiovascular disease and central nervous system disorders, as well as various forms of cancer. SIGNIFICANCE STATEMENT: Regulator of G protein signaling (RGS) proteins represent an exciting class of novel drug targets. RGS2, in particular, could have broad clinical importance. As more details are emerging on the regulation of RGS2 in various physiological systems, the potential utility of this small protein in therapeutic development is increasing.
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Affiliation(s)
- Harrison J McNabb
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Qian Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
| | - Benita Sjögren
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana
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13
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Cheng J, Guo J, North BJ, Tao K, Zhou P, Wei W. The emerging role for Cullin 4 family of E3 ligases in tumorigenesis. Biochim Biophys Acta Rev Cancer 2018; 1871:138-159. [PMID: 30602127 DOI: 10.1016/j.bbcan.2018.11.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 11/28/2018] [Accepted: 11/29/2018] [Indexed: 02/06/2023]
Abstract
As a member of the Cullin-RING ligase family, Cullin-RING ligase 4 (CRL4) has drawn much attention due to its broad regulatory roles under physiological and pathological conditions, especially in neoplastic events. Based on evidence from knockout and transgenic mouse models, human clinical data, and biochemical interactions, we summarize the distinct roles of the CRL4 E3 ligase complexes in tumorigenesis, which appears to be tissue- and context-dependent. Notably, targeting CRL4 has recently emerged as a noval anti-cancer strategy, including thalidomide and its derivatives that bind to the substrate recognition receptor cereblon (CRBN), and anticancer sulfonamides that target DCAF15 to suppress the neoplastic proliferation of multiple myeloma and colorectal cancers, respectively. To this end, PROTACs have been developed as a group of engineered bi-functional chemical glues that induce the ubiquitination-mediated degradation of substrates via recruiting E3 ligases, such as CRL4 (CRBN) and CRL2 (pVHL). We summarize the recent major advances in the CRL4 research field towards understanding its involvement in tumorigenesis and further discuss its clinical implications. The anti-tumor effects using the PROTAC approach to target the degradation of undruggable targets are also highlighted.
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Affiliation(s)
- Ji Cheng
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Jianping Guo
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Brian J North
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Kaixiong Tao
- Department of Gastrointestinal Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Pengbo Zhou
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, 1300 York Ave., New York, NY 10065, USA.
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
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14
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Leysen H, van Gastel J, Hendrickx JO, Santos-Otte P, Martin B, Maudsley S. G Protein-Coupled Receptor Systems as Crucial Regulators of DNA Damage Response Processes. Int J Mol Sci 2018; 19:E2919. [PMID: 30261591 PMCID: PMC6213947 DOI: 10.3390/ijms19102919] [Citation(s) in RCA: 22] [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: 08/22/2018] [Revised: 09/14/2018] [Accepted: 09/15/2018] [Indexed: 12/11/2022] Open
Abstract
G protein-coupled receptors (GPCRs) and their associated proteins represent one of the most diverse cellular signaling systems involved in both physiological and pathophysiological processes. Aging represents perhaps the most complex biological process in humans and involves a progressive degradation of systemic integrity and physiological resilience. This is in part mediated by age-related aberrations in energy metabolism, mitochondrial function, protein folding and sorting, inflammatory activity and genomic stability. Indeed, an increased rate of unrepaired DNA damage is considered to be one of the 'hallmarks' of aging. Over the last two decades our appreciation of the complexity of GPCR signaling systems has expanded their functional signaling repertoire. One such example of this is the incipient role of GPCRs and GPCR-interacting proteins in DNA damage and repair mechanisms. Emerging data now suggest that GPCRs could function as stress sensors for intracellular damage, e.g., oxidative stress. Given this role of GPCRs in the DNA damage response process, coupled to the effective history of drug targeting of these receptors, this suggests that one important future activity of GPCR therapeutics is the rational control of DNA damage repair systems.
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Affiliation(s)
- Hanne Leysen
- Department of Biomedical Sciences, University of Antwerp, 2610 Antwerp, Belgium.
| | - Jaana van Gastel
- Department of Biomedical Sciences, University of Antwerp, 2610 Antwerp, Belgium.
- Translational Neurobiology Group, Center of Molecular Neurology, VIB, 2610 Antwerp, Belgium.
| | - Jhana O Hendrickx
- Department of Biomedical Sciences, University of Antwerp, 2610 Antwerp, Belgium.
- Translational Neurobiology Group, Center of Molecular Neurology, VIB, 2610 Antwerp, Belgium.
| | - Paula Santos-Otte
- Institute of Biophysics, Humboldt-Universität zu Berlin, 10115 Berlin, Germany.
| | - Bronwen Martin
- Department of Biomedical Sciences, University of Antwerp, 2610 Antwerp, Belgium.
| | - Stuart Maudsley
- Department of Biomedical Sciences, University of Antwerp, 2610 Antwerp, Belgium.
- Translational Neurobiology Group, Center of Molecular Neurology, VIB, 2610 Antwerp, Belgium.
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15
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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: 32] [Impact Index Per Article: 4.6] [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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16
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Kanai SM, Edwards AJ, Rurik JG, Osei-Owusu P, Blumer KJ. Proteolytic degradation of regulator of G protein signaling 2 facilitates temporal regulation of G q/11 signaling and vascular contraction. J Biol Chem 2017; 292:19266-19278. [PMID: 28974581 DOI: 10.1074/jbc.m117.797134] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/18/2017] [Indexed: 12/18/2022] Open
Abstract
Regulator of G protein signaling 2 (RGS2) controls signaling by receptors coupled to the Gq/11 class heterotrimeric G proteins. RGS2 deficiency causes several phenotypes in mice and occurs in several diseases, including hypertension in which a proteolytically unstable RGS2 mutant has been reported. However, the mechanisms and functions of RGS2 proteolysis remain poorly understood. Here we addressed these questions by identifying degradation signals in RGS2, and studying dynamic regulation of Gq/11-evoked Ca2+ signaling and vascular contraction. We identified a novel bipartite degradation signal in the N-terminal domain of RGS2. Mutations disrupting this signal blunted proteolytic degradation downstream of E3 ubiquitin ligase binding to RGS2. Analysis of RGS2 mutants proteolyzed at various rates and the effects of proteasome inhibition indicated that proteolytic degradation controls agonist efficacy by setting RGS2 protein expression levels, and affecting the rate at which cells regain agonist responsiveness as synthesis of RGS2 stops. Analyzing contraction of mesenteric resistance arteries supported the biological relevance of this mechanism. Because RGS2 mRNA expression often is strikingly and transiently up-regulated and then down-regulated upon cell stimulation, our findings indicate that proteolytic degradation tightly couples RGS2 transcription, protein levels, and function. Together these mechanisms provide tight temporal control of Gq/11-coupled receptor signaling in the cardiovascular, immune, and nervous systems.
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Affiliation(s)
- Stanley M Kanai
- From the Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Alethia J Edwards
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102
| | - Joel G Rurik
- From the Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Patrick Osei-Owusu
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102
| | - Kendall J Blumer
- From the Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110 and
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17
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Lead discovery and chemical biology approaches targeting the ubiquitin proteasome system. Bioorg Med Chem Lett 2017; 27:4589-4596. [DOI: 10.1016/j.bmcl.2017.08.058] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/24/2017] [Accepted: 08/28/2017] [Indexed: 12/26/2022]
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18
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Sjögren B. The evolution of regulators of G protein signalling proteins as drug targets - 20 years in the making: IUPHAR Review 21. Br J Pharmacol 2017; 174:427-437. [PMID: 28098342 DOI: 10.1111/bph.13716] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 12/11/2016] [Accepted: 01/08/2017] [Indexed: 12/11/2022] Open
Abstract
Regulators of G protein signalling (RGS) proteins are celebrating the 20th anniversary of their discovery. The unveiling of this new family of negative regulators of G protein signalling in the mid-1990s solved a persistent conundrum in the G protein signalling field, in which the rate of deactivation of signalling cascades in vivo could not be replicated in exogenous systems. Since then, there has been tremendous advancement in the knowledge of RGS protein structure, function, regulation and their role as novel drug targets. RGS proteins play an important modulatory role through their GTPase-activating protein (GAP) activity at active, GTP-bound Gα subunits of heterotrimeric G proteins. They also possess many non-canonical functions not related to G protein signalling. Here, an update on the status of RGS proteins as drug targets is provided, highlighting advances that have led to the inclusion of RGS proteins in the IUPHAR/BPS Guide to PHARMACOLOGY database of drug targets.
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Affiliation(s)
- B Sjögren
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
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19
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Sjögren B, Parra S, Atkins KB, Karaj B, Neubig RR. Digoxin-Mediated Upregulation of RGS2 Protein Protects against Cardiac Injury. J Pharmacol Exp Ther 2016; 357:311-9. [PMID: 26941169 PMCID: PMC4851323 DOI: 10.1124/jpet.115.231571] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 03/01/2016] [Indexed: 12/31/2022] Open
Abstract
Regulator of G protein signaling (RGS) proteins have emerged as novel drug targets since their discovery almost two decades ago. RGS2 has received particular interest in cardiovascular research due to its role in regulating Gqsignaling in the heart and vascular smooth muscle. RGS2(-/-)mice are hypertensive, prone to heart failure, and display accelerated kidney fibrosis. RGS2 is rapidly degraded through the proteasome, and human mutations leading to accelerated RGS2 protein degradation correlate with hypertension. Hence, stabilizing RGS2 protein expression could be a novel route in treating cardiovascular disease. We previously identified cardiotonic steroids, including digoxin, as selective stabilizers of RGS2 protein in vitro. In the current study we investigated the functional effects of digoxin-mediated RGS2 protein stabilization in vivo. Using freshly isolated myocytes from wild-type and RGS2(-/-)mice treated with vehicle or low-dose digoxin (2µg/kg/day for 7 days) we demonstrated that agonist-induced cAMP levels and cardiomyocyte contractility was inhibited by digoxin in wild-type but not in RGS2(-/-)mice. This inhibition was accompanied by an increase in RGS2 protein levels in cardiomyocytes as well as in whole heart tissue. Furthermore, digoxin had protective effects in a model of cardiac injury in wild-type mice and this protection was lost in RGS2(-/-)mice. Digoxin is the oldest known therapy for heart failure; however, beyond its activity at the Na(+)/K(+)-ATPase, the exact mechanism of action is not known. The current study adds a novel mechanism, whereby through stabilizing RGS2 protein levels digoxin could exert its protective effects in the failing heart.
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Affiliation(s)
- Benita Sjögren
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (B.S., B.K., R.R.N.); and Department of Pharmacology (S.P.) and Department of Internal Medicine (K.B.A.), University of Michigan, Ann Arbor, Michigan
| | - Sergio Parra
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (B.S., B.K., R.R.N.); and Department of Pharmacology (S.P.) and Department of Internal Medicine (K.B.A.), University of Michigan, Ann Arbor, Michigan
| | - Kevin B Atkins
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (B.S., B.K., R.R.N.); and Department of Pharmacology (S.P.) and Department of Internal Medicine (K.B.A.), University of Michigan, Ann Arbor, Michigan
| | - Behirda Karaj
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (B.S., B.K., R.R.N.); and Department of Pharmacology (S.P.) and Department of Internal Medicine (K.B.A.), University of Michigan, Ann Arbor, Michigan
| | - Richard R Neubig
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan (B.S., B.K., R.R.N.); and Department of Pharmacology (S.P.) and Department of Internal Medicine (K.B.A.), University of Michigan, Ann Arbor, Michigan
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20
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Heo J, Eki R, Abbas T. Deregulation of F-box proteins and its consequence on cancer development, progression and metastasis. Semin Cancer Biol 2015; 36:33-51. [PMID: 26432751 DOI: 10.1016/j.semcancer.2015.09.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 09/25/2015] [Accepted: 09/25/2015] [Indexed: 01/28/2023]
Abstract
F-box proteins are substrate receptors of the SCF (SKP1-Cullin 1-F-box protein) E3 ubiquitin ligase that play important roles in a number of physiological processes and activities. Through their ability to assemble distinct E3 ubiquitin ligases and target key regulators of cellular activities for ubiquitylation and degradation, this versatile group of proteins is able to regulate the abundance of cellular proteins whose deregulated expression or activity contributes to disease. In this review, we describe the important roles of select F-box proteins in regulating cellular activities, the perturbation of which contributes to the initiation and progression of a number of human malignancies.
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Affiliation(s)
- Jinho Heo
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA, USA
| | - Rebeka Eki
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA, USA; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA
| | - Tarek Abbas
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA, USA; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA; Center for Cell Signaling, University of Virginia, Charlottesville, VA, USA.
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