1
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Tang JQ, Marchand MM, Veggiani G. Ubiquitin Engineering for Interrogating the Ubiquitin-Proteasome System and Novel Therapeutic Strategies. Cells 2023; 12:2117. [PMID: 37626927 PMCID: PMC10453149 DOI: 10.3390/cells12162117] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/10/2023] [Accepted: 08/11/2023] [Indexed: 08/27/2023] Open
Abstract
Protein turnover, a highly regulated process governed by the ubiquitin-proteasome system (UPS), is essential for maintaining cellular homeostasis. Dysregulation of the UPS has been implicated in various diseases, including viral infections and cancer, making the proteins in the UPS attractive targets for therapeutic intervention. However, the functional and structural redundancies of UPS enzymes present challenges in identifying precise drug targets and achieving target selectivity. Consequently, only 26S proteasome inhibitors have successfully advanced to clinical use thus far. To overcome these obstacles, engineered peptides and proteins, particularly engineered ubiquitin, have emerged as promising alternatives. In this review, we examine the impact of engineered ubiquitin on UPS and non-UPS proteins, as well as on viral enzymes. Furthermore, we explore their potential to guide the development of small molecules targeting novel surfaces, thereby expanding the range of druggable targets.
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Affiliation(s)
- Jason Q. Tang
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, ON M5S3E1, Canada
- Department of Molecular Genetics, University of Toronto, 160 College Street, Toronto, ON M5S3E1, Canada
| | - Mary M. Marchand
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Gianluca Veggiani
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
- Division of Biotechnology and Molecular Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
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2
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Ares GR. Ubiquitination of NKCC2 by the cullin-RING E3 ubiquitin ligase family in the thick ascending limb of the loop of Henle. Am J Physiol Renal Physiol 2023; 324:F315-F328. [PMID: 36727946 PMCID: PMC9988521 DOI: 10.1152/ajprenal.00079.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The Na+/K+/2Cl- cotransporter (NKCC2) in the thick ascending limb of the loop of Henle (TAL) mediates NaCl reabsorption. cGMP, the second messenger of nitric oxide and atrial natriuretic peptide, inhibits NKCC2 activity by stimulating NKCC2 ubiquitination and decreasing surface NKCC2 levels. Among the E3 ubiquitin ligase families, the cullin-RING E3 ubiquitin ligase (CRL) family is the largest. Cullins are molecular scaffold proteins that recruit multiple subunits to form the CRL complex. We hypothesized that a CRL complex mediates the cGMP-dependent increase in NKCC2 ubiquitination in TALs. Cullin-1, cullin-2, cullin-3, cullin-4A, and cullin-5 were expressed at the protein level, whereas the other members of the cullin family were expressed at the mRNA level, in rat TALs. CRL complex activity is regulated by neuronal precursor cell-expressed developmentally downregulated protein 8 (Nedd8) to cullins, a process called neddylation. Inhibition of cullin neddylation blunted the cGMP-dependent increase in ubiquitinated NKCC2 while increasing the expression of cullin-1 by threefold, but this effect was not seen with other cullins. CRL complex activity is also regulated by cullin-associated Nedd8-dissociated 1 (CAND1). CAND1 binds to cullins and promotes the exchange of substrate-recognition proteins to target different proteins for ubiquitination. CAND1 inhibition exacerbated the cGMP-dependent increase in NKCC2 ubiquitination and decreased surface NKCC2 expression. Finally, cGMP increased neddylation of cullins. We conclude that the cGMP-dependent increase in NKCC2 ubiquitination is mediated by a CRL complex. To the best of our knowledge, this is the first evidence that a CRL complex mediates NKCC2 ubiquitination in native TALs.NEW & NOTEWORTHY The Na+/K+/2Cl- cotransporter (NKCC2) reabsorbs NaCl by the thick ascending limb. Nitric oxide and atrial natriuretic peptide decrease NaCl reabsorption in thick ascending limbs by increasing the second messenger cGMP. The present findings indicate that cGMP increases NKCC2 ubiquitination via a cullin-RING ligase complex and regulates in part surface NKCC2 levels. Identifying the E3 ubiquitin ligases that regulate NKCC2 expression and activity may provide new targets for the development of specific loop diuretics.
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Affiliation(s)
- Gustavo R Ares
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan, United States.,Department of Physiology, Integrative Bioscience Center, Wayne State University, Detroit, Michigan, United States
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3
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Qu Y, Lu Y, Zhang D, Liu X, Fan P, Chen J, Zhang H, Yang K, Tian T, Zhou Y, Zhang Q, Zhang Y, Wang L, Huang Z, Liu Y, Hu A, Zhou X. Identification of a novel frameshift mutation in the SCNN1B causing Liddle syndrome. Sci Bull (Beijing) 2023; 68:383-387. [PMID: 36774301 DOI: 10.1016/j.scib.2023.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/16/2023] [Accepted: 01/30/2023] [Indexed: 02/10/2023]
Affiliation(s)
- Yi Qu
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Yiting Lu
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Di Zhang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Xinchang Liu
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Peng Fan
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Jiexin Chen
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Hanbo Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Kunqi Yang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Tao Tian
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Yi Zhou
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Qiongyu Zhang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China
| | - Yu Zhang
- Institute of Laboratory Animal Sciences, Comparative Medicine Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, China
| | - Linping Wang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China.
| | - Yaxin Liu
- Emergency and Critical Care Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
| | - Aihua Hu
- Department of Non-Communicable Disease Management, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China.
| | - Xianliang Zhou
- Hypertension Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, China.
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4
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Pratamawati TM, Alwi I. Summary of Known Genetic and Epigenetic Modification Contributed to Hypertension. Int J Hypertens 2023; 2023:5872362. [PMID: 37201134 PMCID: PMC10188269 DOI: 10.1155/2023/5872362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 04/07/2023] [Accepted: 04/13/2023] [Indexed: 05/20/2023] Open
Abstract
Hypertension is a multifactorial disease due to a complex interaction among genetic, epigenetic, and environmental factors. Characterized by raised blood pressure (BP), it is responsible for more than 7 million deaths per annum by acting as a leading preventable risk factor for cardiovascular disease. Reports suggest that genetic factors are estimated to be involved in approximately 30 to 50% of BP variation, and epigenetic marks are known to contribute to the initiation of the disease by influencing gene expression. Consequently, elucidating the genetic and epigenetic mediators associated with hypertension is essential for better discernment of its pathophysiology. By deciphering the unprecedented molecular hypertension basis, it could help to unravel an individual's inclination towards hypertension which eventually could result in an arrangement of potential strategies for prevention and therapy. In the present review, we discuss known genetic and epigenetic drivers that contributed to the hypertension development and summarize the novel variants that have currently been identified. The effect of these molecular alterations on endothelial function was also presented.
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Affiliation(s)
- Tiar Masykuroh Pratamawati
- Program Doctoral Biomedical Science, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
- Department of Genetics, Faculty of Medicine, Universitas Swadaya Gunung Jati, Cirebon, Indonesia
| | - Idrus Alwi
- Division of Cardiology, Department of Internal Medicine, Faculty of Medicine, Universitas Indonesia, Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia
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5
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Metwalley KA, Farghaly HS. Overview of endocrine hypertension in children. PROGRESS IN PEDIATRIC CARDIOLOGY 2022. [DOI: 10.1016/j.ppedcard.2022.101581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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6
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Research progress of Nedd4L in cardiovascular diseases. Cell Death Dis 2022; 8:206. [PMID: 35429991 PMCID: PMC9013375 DOI: 10.1038/s41420-022-01017-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/31/2022] [Accepted: 04/01/2022] [Indexed: 11/25/2022]
Abstract
Post-translational modifications (PTMs) are a covalent processing process of proteins after translation. Proteins are capable of playing their roles only after being modified, so as to maintain the normal physiological function of cells. As a key modification of protein post-translational modification, ubiquitination is an essential element, which forms an enzyme-linked reaction through ubiquitin-activating enzyme, ubiquitin binding enzyme, and ubiquitin ligase, aiming to regulate the expression level and function of cellular proteins. Nedd4 family is the largest group of ubiquitin ligases, including 9 members, such as Nedd4-1, Nedd4L (Nedd4-2), WWP1, WWP2, ITCH, etc. They could bind to substrate proteins through their WW domain and play a dominant role in the ubiquitination process, and then participate in various pathophysiological processes of cardiovascular diseases (such as hypertension, myocardial hypertrophy, heart failure, etc.). At present, the role of Nedd4L in the cardiovascular field is not fully understood. This review aims to summarize the progress and mechanism of Nedd4L in cardiovascular diseases, and provide potential perspective for the clinical treatment or prevention of related cardiovascular diseases by targeting Nedd4L.
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7
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Tsilosani A, Gao C, Zhang W. Aldosterone-Regulated Sodium Transport and Blood Pressure. Front Physiol 2022; 13:770375. [PMID: 35197862 PMCID: PMC8859437 DOI: 10.3389/fphys.2022.770375] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 01/06/2022] [Indexed: 11/13/2022] Open
Abstract
Aldosterone is a major mineralocorticoid steroid hormone secreted by glomerulosa cells in the adrenal cortex. It regulates a variety of physiological responses including those to oxidative stress, inflammation, fluid disruption, and abnormal blood pressure through its actions on various tissues including the kidney, heart, and the central nervous system. Aldosterone synthesis is primarily regulated by angiotensin II, K+ concentration, and adrenocorticotrophic hormone. Elevated serum aldosterone levels increase blood pressure largely by increasing Na+ re-absorption in the kidney through regulating transcription and activity of the epithelial sodium channel (ENaC). This review focuses on the signaling pathways involved in aldosterone synthesis and its effects on Na+ reabsorption through ENaC.
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Affiliation(s)
- Akaki Tsilosani
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
| | - Chao Gao
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
| | - Wenzheng Zhang
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
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8
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Abstract
The WW domain is a modular protein structure that recognizes the proline-rich Pro-Pro-x-Tyr (PPxY) motif contained in specific target proteins. The compact modular nature of the WW domain makes it ideal for mediating interactions between proteins in complex networks and signaling pathways of the cell (e.g. the Hippo pathway). As a result, WW domains play key roles in a plethora of both normal and disease processes. Intriguingly, RNA and DNA viruses have evolved strategies to hijack cellular WW domain-containing proteins and thereby exploit the modular functions of these host proteins for various steps of the virus life cycle, including entry, replication, and egress. In this review, we summarize key findings in this rapidly expanding field, in which new virus-host interactions continue to be identified. Further unraveling of the molecular aspects of these crucial virus-host interactions will continue to enhance our fundamental understanding of the biology and pathogenesis of these viruses. We anticipate that additional insights into these interactions will help support strategies to develop a new class of small-molecule inhibitors of viral PPxY-host WW-domain interactions that could be used as antiviral therapeutics.
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Affiliation(s)
- Ariel Shepley-McTaggart
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Hao Fan
- Bioinformatics Institute, Agency for Science, Technology, and Research (A*STAR), 30 Biopolis Street, Matrix #07-01, Singapore 138671.,Department of Biological Sciences (DBS), National University of Singapore, Singapore 119077.,Center for Computational Biology, DUKE-NUS Medical School, Singapore 169857
| | - Marius Sudol
- Department of Physiology, National University of Singapore, Singapore 119077.,Laboratory of Cancer Signaling and Domainopathies, Yong Loo Li School of Medicine, Block MD9, 2 Medical Drive #04-01, Singapore 117597.,Mechanobiology Institute, T-Lab, 5A Engineering Drive 1, Singapore 117411.,Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Ronald N Harty
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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9
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Abstract
Liddle syndrome is an inherited form of low-renin hypertension, transmitted with an autosomal dominant pattern. The molecular basis of Liddle syndrome resides in germline mutations of the SCNN1A, SCNN1B and SCNN1G genes, encoding the α, β, and γ-subunits of the epithelial Na+ channel (ENaC), respectively. To date, 31 different causative mutations have been reported in 72 families from four continents. The majority of the substitutions cause an increased expression of the channel at the distal nephron apical membrane, with subsequent enhanced renal sodium reabsorption. The most common clinical presentation of the disease is early onset hypertension, hypokalemia, metabolic alkalosis, suppressed plasma renin activity and low plasma aldosterone. Consequently, treatment of Liddle syndrome is based on the administration of ENaC blockers, amiloride and triamterene. Herein, we discuss the genetic basis, clinical presentation, diagnosis and treatment of Liddle syndrome. Finally, we report a new case in an Italian family, caused by a SCNN1B p.Pro618Leu substitution.
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10
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Abstract
The heritability of hypertension (HTN) is widely recognized and as a result, extensive studies ranging from genetic linkage analyses to genome-wide association studies are actively ongoing to elucidate the etiology of both monogenic and polygenic forms of HTN. Due to the complex nature of essential HTN, however, single genes affecting blood pressure (BP) variability remain difficult to isolate and identify and have rendered the development of single-gene targeted therapies challenging. The roles of other causative factors in modulating BP, such as gene-environment interactions and epigenetic factors, are increasingly being brought to the forefront. In this review, we discuss the various monogenic HTN syndromes and corresponding pathophysiologic mechanisms, the different methodologies employed in genetic studies of essential HTN, the mechanisms for epigenetic modulation of essential HTN, pharmacogenomics and HTN, and finally, recent advances in genetic studies of essential HTN in the pediatric population.
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Affiliation(s)
- Sun-Young Ahn
- Department of Nephrology, Children's National Health System, Washington, DC, United States.,The George Washington University School of Medicine, Washington, DC, United States
| | - Charu Gupta
- Department of Nephrology, Children's National Health System, Washington, DC, United States.,The George Washington University School of Medicine, Washington, DC, United States
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11
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Selective compounds enhance osteoblastic activity by targeting HECT domain of ubiquitin ligase Smurf1. Oncotarget 2016; 8:50521-50533. [PMID: 28881580 PMCID: PMC5584161 DOI: 10.18632/oncotarget.10648] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 05/29/2016] [Indexed: 01/07/2023] Open
Abstract
The HECT-type ubiquitin ligase Smurf1 (Smad ubiquitination regulatory factor-1) plays the prominent role in regulation of bone formation, embryonic development, and tumorigenesis by directing the ubiquitin-proteasomal degradation of specific targets. In contrast with RING-type E3s, the catalytic HECT domain of Smurf1 firstly binds to and then transfers ubiquitin (Ub) molecules onto the substrates. The Smurf1-Ub interaction is required for Smurf1 catalytic ligase activity to promote substrate degradation. However, so far specific regulators or compounds controlling Smurf1-Ub interaction and the ligase activity have not been identified. Here we report two small molecule compounds targeting Ub binding region of HECT domain interrupt Smurf1-Ub contact, inhibit Smurf1 ligase activity and stabilize BMP signal components Smad1/5 protein level. Furthermore, these compounds increase BMP signal responsiveness and enhance osteoblastic activity in cultured cells. These findings provide a novel strategy through targeting Smurf1 ligase activity to potentially treat bone disorders such as osteoporosis.
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12
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Hanukoglu I, Hanukoglu A. Epithelial sodium channel (ENaC) family: Phylogeny, structure-function, tissue distribution, and associated inherited diseases. Gene 2016; 579:95-132. [PMID: 26772908 PMCID: PMC4756657 DOI: 10.1016/j.gene.2015.12.061] [Citation(s) in RCA: 250] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 12/20/2015] [Accepted: 12/22/2015] [Indexed: 01/24/2023]
Abstract
The epithelial sodium channel (ENaC) is composed of three homologous subunits and allows the flow of Na(+) ions across high resistance epithelia, maintaining body salt and water homeostasis. ENaC dependent reabsorption of Na(+) in the kidney tubules regulates extracellular fluid (ECF) volume and blood pressure by modulating osmolarity. In multi-ciliated cells, ENaC is located in cilia and plays an essential role in the regulation of epithelial surface liquid volume necessary for cilial transport of mucus and gametes in the respiratory and reproductive tracts respectively. The subunits that form ENaC (named as alpha, beta, gamma and delta, encoded by genes SCNN1A, SCNN1B, SCNN1G, and SCNN1D) are members of the ENaC/Degenerin superfamily. The earliest appearance of ENaC orthologs is in the genomes of the most ancient vertebrate taxon, Cyclostomata (jawless vertebrates) including lampreys, followed by earliest representatives of Gnathostomata (jawed vertebrates) including cartilaginous sharks. Among Euteleostomi (bony vertebrates), Actinopterygii (ray finned-fishes) branch has lost ENaC genes. Yet, most animals in the Sarcopterygii (lobe-finned fish) branch including Tetrapoda, amphibians and amniotes (lizards, crocodiles, birds, and mammals), have four ENaC paralogs. We compared the sequences of ENaC orthologs from 20 species and established criteria for the identification of ENaC orthologs and paralogs, and their distinction from other members of the ENaC/Degenerin superfamily, especially ASIC family. Differences between ENaCs and ASICs are summarized in view of their physiological functions and tissue distributions. Structural motifs that are conserved throughout vertebrate ENaCs are highlighted. We also present a comparative overview of the genotype-phenotype relationships in inherited diseases associated with ENaC mutations, including multisystem pseudohypoaldosteronism (PHA1B), Liddle syndrome, cystic fibrosis-like disease and essential hypertension.
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Affiliation(s)
- Israel Hanukoglu
- Laboratory of Cell Biology, Faculty of Natural Sciences, Ariel University, Ariel, Israel.
| | - Aaron Hanukoglu
- Division of Pediatric Endocrinology, E. Wolfson Medical Center, Holon, Israel; Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel
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13
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The degradation of the inwardly rectifying potassium channel, Kir2.1, depends on the expression level: examination with fluorescent proteins. Brain Res 2013; 1528:8-19. [PMID: 23850646 DOI: 10.1016/j.brainres.2013.07.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Revised: 07/01/2013] [Accepted: 07/05/2013] [Indexed: 01/24/2023]
Abstract
The expression of ion channels is regulated by their synthesis as well as degradation, and some ion channels are degraded in an expression level-dependent way. Recently, new techniques of fluorescent proteins have been developed and seem to be useful to study protein degradation. To examine the regulation of the degradation of strongly inwardly rectifying potassium channel (Kir2.1) and the usefulness of the fluorescent proteins, we constructed Kir2.1 fusion proteins with SNAP tag and fluorescent timer (FT). The SNAP tag, which covalently binds to a specific membrane-permeable fluorescent dye, enables a pulse-chase experiment with fluorescence. When the SNAP-Kir2.1 proteins were expressed in 293T cells by low and high expression plasmids, the half-life of the fusion protein expressed by a high-expression plasmid was shorter (18.2±1.9 h) than that expressed by a low-expression plasmid (35.1+2.3h). The addition of Ba(2+), a selective blocker of Kir2.1, slowed the degradation, suggesting a current-dependency of degradation. Consistently, patch-clamp recording showed that cultivation in the presence of Ba(2+) increased the whole cell conductance of SNAP-Kir2.1. Since the fluorescence of FT changes gradually changes from green to red, the green/red ratio should allow us to monitor the changes in the degradation rate of FT-Kir2.1. Using this method, we confirmed the slower degradation by Ba(2+). The results suggest a homeostatic regulation of the degradation of Kir2.1 in the 293T cells, and the usefulness of fluorescence-based methods for examining the degradation of ion channels.
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Abstract
Liddle syndrome is monogenic hypertension caused by mutations in the epithelial Na+ channel (ENaC) that interfere with its ubiquitylation by Nedd4-2. In this issue, Ronzaud and colleagues found that deleting Nedd4-2 from kidney tubules in adult mice led to ENaC accumulation, but not at the plasma membrane, as predicted from current models. Instead, abundance of the sodium chloride transporter NCC increased at the plasma membrane, and the mice have some features of increased NCC activity. Together, the results suggest that defective ubiquitylation of ENaC by Nedd4-2 may not fully explain Liddle syndrome and that Nedd4-2 modulates NCC more strongly.
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Affiliation(s)
- David H Ellison
- Division of Nephrology and Hypertension, CH12R, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
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15
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Zaydman MA, Silva JR, Cui J. Ion channel associated diseases: overview of molecular mechanisms. Chem Rev 2012; 112:6319-33. [PMID: 23151230 DOI: 10.1021/cr300360k] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Mark A Zaydman
- Department of Biomedical Engineering, Washington University, Saint Louis, Missouri 63130, United States
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16
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Affiliation(s)
- Ivana Y Kuo
- Departments of †Pharmacology and ‡Cellular and Molecular Physiology School of Medicine, Yale University , 333 Cedar Street, New Haven, Connecticut 06520
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18
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Abstract
Over the past 14 years, ubiquitination has emerged as a centrally important mechanism governing the subcellular trafficking of proteins. Ubiquitination, interaction with sorting factors that contain ubiquitin-binding domains, and deubiquitination govern the itineraries of cargo proteins that include yeast carboxypeptidase S, the epithelial sodium channel ENaC, and epidermal growth factor receptor. The molecular structures and mechanisms of the paradigmatic HECT and RING domain ubiquitin ligases, of JAMM- and USP-domain-deubiquitinating enzymes, and of numerous ubiquitin-binding domains involved in these pathways have been worked out in recent years and are described.
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Affiliation(s)
- James H Hurley
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0580, USA.
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19
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Carraway KL. E3 ubiquitin ligases in ErbB receptor quantity control. Semin Cell Dev Biol 2010; 21:936-43. [PMID: 20868762 DOI: 10.1016/j.semcdb.2010.09.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 09/15/2010] [Indexed: 02/08/2023]
Abstract
Signaling through ErbB family growth factor receptor tyrosine kinases is necessary for the development and homeostasis of a wide variety of tissue types. However, the intensity of receptor-mediated cellular signaling must fall within a precise range; insufficient signaling can lead to developmental abnormalities or tissue atrophy, while over-signaling can lead to hyperplastic and ultimately neoplastic events. While a plethora of mechanisms have been described that regulate downstream signaling events, it appears that cells also utilize various mechanisms to regulate their ErbB receptor levels. Such mechanisms are collectively termed "ErbB receptor quantity control." Notably, studies over the past few years have highlighted roles for post-transcriptional processes, particularly protein degradation, in ErbB quantity control. Here the involvement of ErbB-directed E3 ubiquitin ligases is discussed, including Nrdp1-mediated ErbB3 degradation, ErbB4 degradation mediated by Nedd4 family E3 ligases, and CHIP-mediated ErbB2 degradation. The hypothesis is forwarded that protein degradation-based ErbB quantity control mechanisms play central roles in suppressing receptor overexpression in normal cells, and that the loss of such mechanisms could facilitate the onset or progression of ErbB-dependent tumors.
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20
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Liu C, Choe V, Rao H. Genome-wide approaches to systematically identify substrates of the ubiquitin-proteasome pathway. Trends Biotechnol 2010; 28:461-7. [PMID: 20637515 DOI: 10.1016/j.tibtech.2010.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 06/03/2010] [Accepted: 06/11/2010] [Indexed: 01/23/2023]
Abstract
The ubiquitin-proteasome system handles the majority of controlled proteolysis in eukaryotes. Defects in the ubiquitin-proteasome system have been implicated in diseases ranging from cancers to neurodegenerative disorders. However, the precise role of ubiquitin-proteasome-mediated degradation in health and disease is far from clear. A major challenge is to link specific substrates directly to a particular degradation pathway. Here, we review genome-wide approaches that have been developed in recent years to comprehensively identify ubiquitylated substrates of a particular pathway. Components of the ubiquitin-proteasome system are attractive drug targets, as illustrated by the efficacy of some proteasome inhibitors in the treatment of multiple myeloma. Information that has emerged from these studies could reveal novel drug targets and strategies for treating human diseases.
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Affiliation(s)
- Chang Liu
- Institute of Biotechnology, Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78245, USA
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Butterworth MB. Regulation of the epithelial sodium channel (ENaC) by membrane trafficking. Biochim Biophys Acta Mol Basis Dis 2010; 1802:1166-77. [PMID: 20347969 DOI: 10.1016/j.bbadis.2010.03.010] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 03/15/2010] [Accepted: 03/20/2010] [Indexed: 02/07/2023]
Abstract
The epithelial Na(+) channel (ENaC) is a major regulator of salt and water reabsorption in a number of epithelial tissues. Abnormalities in ENaC function have been directly linked to several human disease states including Liddle syndrome, psuedohypoaldosteronism, and cystic fibrosis and may be implicated in salt-sensitive hypertension. ENaC activity in epithelial cells is regulated both by open probability and channel number. This review focuses on the regulation of ENaC in the cells of the kidney cortical collecting duct by trafficking and recycling. The trafficking of ENaC is discussed in the broader context of epithelial cell vesicle trafficking. Well-characterized pathways and protein interactions elucidated using epithelial model cells are discussed, and the known overlap with ENaC regulation is highlighted. In following the life of ENaC in CCD epithelial cells the apical delivery, internalization, recycling, and destruction of the channel will be discussed. While a number of pathways presented still need to be linked to ENaC regulation and many details of the regulation of ENaC trafficking remain to be elucidated, knowledge of these mechanisms may provide further insights into ENaC activity in normal and disease states.
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Affiliation(s)
- Michael B Butterworth
- Department Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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Edelheit O, Hanukoglu I, Shriki Y, Tfilin M, Dascal N, Gillis D, Hanukoglu A. Truncated beta epithelial sodium channel (ENaC) subunits responsible for multi-system pseudohypoaldosteronism support partial activity of ENaC. J Steroid Biochem Mol Biol 2010; 119:84-8. [PMID: 20064610 DOI: 10.1016/j.jsbmb.2010.01.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 12/31/2009] [Accepted: 01/04/2010] [Indexed: 10/20/2022]
Abstract
Aldosterone regulated epithelial sodium channels (ENaC) are constructed of three homologous subunits. Mutations in the alpha-, beta- and gamma-ENaC subunit genes (SCNN1A, SCNN1B and SCNN1G) are associated with multi-system pseudohypoaldosteronism (PHA), and mutations in the PY motif of carboxy-terminal region of beta and gamma subunits are associated with Liddle syndrome of hereditary hypertension. In this study we identified two frameshift mutations in the SCNN1B alleles of a female infant diagnosed with multi-system PHA inherited from her parents. This is the first case of PHA in an Ashkenazi family in Israel. The p.Glu217fs (c.648dupA in exon 4) and p.Tyr306fs (c.915delC in exon 6) mutations produce shortened beta-ENaC subunits with 253 and 317 residues respectively instead of the 640 residues present in beta-ENaC subunit. Expression of cRNAs carrying these mutations in Xenopus oocytes showed that the mutations drastically reduce but do not eliminate ENaC activity. The findings reveal that truncated beta-ENaC subunits are capable of partially supporting intracellular transport of the other two subunits to the membrane and the final assembly of a weakly active channel together with normal alpha- and gamma-ENaC subunits. Moreover, these results enhance our understanding of the long-term consequences of these types of mutations in PHA patients.
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Affiliation(s)
- Oded Edelheit
- Department of Molecular Biology, Ariel University Center, Ariel, Israel
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Kamadurai HB, Souphron J, Scott DC, Duda DM, Miller DJ, Stringer D, Piper RC, Schulman BA. Insights into ubiquitin transfer cascades from a structure of a UbcH5B approximately ubiquitin-HECT(NEDD4L) complex. Mol Cell 2010; 36:1095-102. [PMID: 20064473 DOI: 10.1016/j.molcel.2009.11.010] [Citation(s) in RCA: 223] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Revised: 09/01/2009] [Accepted: 09/23/2009] [Indexed: 01/25/2023]
Abstract
In E1-E2-E3 ubiquitin (Ub) conjugation cascades, the E2 first forms a transient E2 approximately Ub covalent complex and then interacts with an E3 for Ub transfer. For cascades involving E3s in the HECT class, Ub is transferred from an associated E2 to the acceptor cysteine in the HECT domain C lobe. To gain insights into this process, we determined the crystal structure of a complex between the HECT domain of NEDD4L and the E2 UbcH5B bearing a covalently linked Ub at its active site (UbcH5B approximately Ub). Noncovalent interactions between UbcH5B and the HECT N lobe and between Ub and the HECT domain C lobe lead to an overall compact structure, with the Ub C terminus sandwiched between UbcH5B and HECT domain active sites. The structure suggests a model for E2-to-HECT Ub transfer, in which interactions between a donor Ub and an acceptor domain constrain upstream and downstream enzymes for conjugation.
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Affiliation(s)
- Hari B Kamadurai
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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Loffing J, Korbmacher C. Regulated sodium transport in the renal connecting tubule (CNT) via the epithelial sodium channel (ENaC). Pflugers Arch 2009; 458:111-35. [PMID: 19277701 DOI: 10.1007/s00424-009-0656-0] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 02/18/2009] [Accepted: 02/22/2009] [Indexed: 12/29/2022]
Abstract
The aldosterone-sensitive distal nephron (ASDN) includes the late distal convoluted tubule 2, the connecting tubule (CNT) and the collecting duct. The appropriate regulation of sodium (Na(+)) absorption in the ASDN is essential to precisely match urinary Na(+) excretion to dietary Na(+) intake whilst taking extra-renal Na(+) losses into account. There is increasing evidence that Na(+) transport in the CNT is of particular importance for the maintenance of body Na(+) balance and for the long-term control of extra-cellular fluid volume and arterial blood pressure. Na(+) transport in the CNT critically depends on the activity and abundance of the amiloride-sensitive epithelial sodium channel (ENaC) in the luminal membrane of the CNT cells. As a rate-limiting step for transepithelial Na(+) transport, ENaC is the main target of hormones (e.g. aldosterone, angiotensin II, vasopressin and insulin/insulin-like growth factor 1) to adjust transepithelial Na(+) transport in this tubular segment. In this review, we highlight the structural and functional properties of the CNT that contribute to the high Na(+) transport capacity of this segment. Moreover, we discuss some aspects of the complex pathways and molecular mechanisms involved in ENaC regulation by hormones, kinases, proteases and associated proteins that control its function. Whilst cultured cells and heterologous expression systems have greatly advanced our knowledge about some of these regulatory mechanisms, future studies will have to determine the relative importance of the various pathways in the native tubule and in particular in the CNT.
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Abstract
The ubiquitin system of protein modification has emerged as a crucial mechanism involved in the regulation of a wide array of cellular processes. As our knowledge of the pathways in this system has grown, so have the ties between the protein ubiquitin and human disease. The power of the ubiquitin system for therapeutic benefit blossomed with the approval of the proteasome inhibitor Velcade in 2003 by the FDA. Current drug discovery activities in the ubiquitin system seek to (i) expand the development of new proteasome inhibitors with distinct mechanisms of action and improved bioavailability, and (ii) validate new targets. This review summarizes our current understanding of the role of the ubiquitin system in various human diseases ranging from cancer, viral infection and neurodegenerative disorders to muscle wasting, diabetes and inflammation. I provide an introduction to the ubiquitin system, highlight some emerging relationships between the ubiquitin system and disease, and discuss current and future efforts to harness aspects of this potentially powerful system for improving human health. Republished from Current BioData's Targeted Proteins database (TPdb; ).
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