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Loeffler DA. Enhancing of cerebral Abeta clearance by modulation of ABC transporter expression: a review of experimental approaches. Front Aging Neurosci 2024; 16:1368200. [PMID: 38872626 PMCID: PMC11170721 DOI: 10.3389/fnagi.2024.1368200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 05/01/2024] [Indexed: 06/15/2024] Open
Abstract
Clearance of amyloid-beta (Aβ) from the brain is impaired in both early-onset and late-onset Alzheimer's disease (AD). Mechanisms for clearing cerebral Aβ include proteolytic degradation, antibody-mediated clearance, blood brain barrier and blood cerebrospinal fluid barrier efflux, glymphatic drainage, and perivascular drainage. ATP-binding cassette (ABC) transporters are membrane efflux pumps driven by ATP hydrolysis. Their functions include maintenance of brain homeostasis by removing toxic peptides and compounds, and transport of bioactive molecules including cholesterol. Some ABC transporters contribute to lowering of cerebral Aβ. Mechanisms suggested for ABC transporter-mediated lowering of brain Aβ, in addition to exporting of Aβ across the blood brain and blood cerebrospinal fluid barriers, include apolipoprotein E lipidation, microglial activation, decreased amyloidogenic processing of amyloid precursor protein, and restricting the entrance of Aβ into the brain. The ABC transporter superfamily in humans includes 49 proteins, eight of which have been suggested to reduce cerebral Aβ levels. This review discusses experimental approaches for increasing the expression of these ABC transporters, clinical applications of these approaches, changes in the expression and/or activity of these transporters in AD and transgenic mouse models of AD, and findings in the few clinical trials which have examined the effects of these approaches in patients with AD or mild cognitive impairment. The possibility that therapeutic upregulation of ABC transporters which promote clearance of cerebral Aβ may slow the clinical progression of AD merits further consideration.
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Affiliation(s)
- David A. Loeffler
- Department of Neurology, Beaumont Research Institute, Corewell Health, Royal Oak, MI, United States
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Ni C, Hong M. Oligomerization of drug transporters: Forms, functions, and mechanisms. Acta Pharm Sin B 2024; 14:1924-1938. [PMID: 38799641 PMCID: PMC11119549 DOI: 10.1016/j.apsb.2024.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 12/07/2023] [Accepted: 01/05/2024] [Indexed: 05/29/2024] Open
Abstract
Drug transporters are essential players in the transmembrane transport of a wide variety of clinical drugs. The broad substrate spectra and versatile distribution pattern of these membrane proteins infer their pharmacological and clinical significance. With our accumulating knowledge on the three-dimensional structure of drug transporters, their oligomerization status has become a topic of intense study due to the possible functional roles carried out by such kind of post-translational modification (PTM). In-depth studies of oligomeric complexes formed among drug transporters as well as their interactions with other regulatory proteins can help us better understand the regulatory mechanisms of these membrane proteins, provide clues for the development of novel drugs, and improve the therapeutic efficacy. In this review, we describe different oligomerization forms as well as their structural basis of major drug transporters in the ATP-binding cassette and solute carrier superfamilies, summarize our current knowledge on the influence of oligomerization for protein expression level and transport function of these membrane proteins, and discuss the regulatory mechanisms of oligomerization. Finally, we highlight the challenges associated with the current oligomerization studies and propose some thoughts on the pharmaceutical application of this important drug transporter PTM.
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Affiliation(s)
- Chunxu Ni
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Mei Hong
- College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, South China Agricultural University, Guangzhou 510642, China
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3
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Vulin M, Zhong Y, Maloney BJ, Bauer B, Hartz AMS. Proteasome inhibition protects blood-brain barrier P-glycoprotein and lowers Aβ brain levels in an Alzheimer's disease model. Fluids Barriers CNS 2023; 20:70. [PMID: 37803468 PMCID: PMC10559617 DOI: 10.1186/s12987-023-00470-z] [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: 04/17/2023] [Accepted: 09/23/2023] [Indexed: 10/08/2023] Open
Abstract
BACKGROUND Loss of P-glycoprotein (P-gp) at the blood-brain barrier contributes to amyloid-β (Aβ) brain accumulation in Alzheimer's disease (AD). Using transgenic human amyloid precursor protein (hAPP)-overexpressing mice (Tg2576), we previously showed that Aβ triggers P-gp loss by activating the ubiquitin-proteasome pathway, which leads to P-gp degradation. Furthermore, we showed that inhibiting the ubiquitin-activating enzyme (E1) prevents P-gp loss and lowers Aβ accumulation in the brain of hAPP mice. Based on these data, we hypothesized that repurposing the FDA-approved proteasome inhibitor, bortezomib (Velcade®; BTZ), protects blood-brain barrier P-gp from degradation in hAPP mice in vivo. METHODS We treated hAPP mice with the proteasome inhibitor BTZ or a combination of BTZ with the P-gp inhibitor cyclosporin A (CSA) for 2 weeks. Vehicle-treated wild-type (WT) mice were used as a reference for normal P-gp protein expression and transport activity. In addition, we used the opioid receptor agonist loperamide as a P-gp substrate in tail flick assays to indirectly assess P-gp transport activity at the blood-brain barrier in vivo. We also determined P-gp protein expression by Western blotting, measured P-gp transport activity levels in isolated brain capillaries with live cell confocal imaging and assessed Aβ plasma and brain levels with ELISA. RESULTS We found that 2-week BTZ treatment of hAPP mice restored P-gp protein expression and transport activity in brain capillaries to levels found in WT mice. We also observed that hAPP mice displayed significant loperamide-induced central antinociception compared to WT mice indicating impaired P-gp transport activity at the blood-brain barrier of hAPP mice in vivo. Furthermore, BTZ treatment prevented loperamide-induced antinociception suggesting BTZ protected P-gp loss in hAPP mice. Further, BTZ-treated hAPP mice had lower Aβ40 and Aβ42 brain levels compared to vehicle-treated hAPP mice. CONCLUSIONS Our data indicate that BTZ protects P-gp from proteasomal degradation in hAPP mice, which helps to reduce Aβ brain levels. Our data suggest that the proteasome system could be exploited for a novel therapeutic strategy in AD, particularly since increasing Aβ transport across the blood-brain barrier may prove an effective treatment for patients.
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Affiliation(s)
- Milica Vulin
- Sanders-Brown Center On Aging, University of Kentucky, Lexington, KY, USA
| | - Yu Zhong
- Sanders-Brown Center On Aging, University of Kentucky, Lexington, KY, USA
| | - Bryan J Maloney
- Sanders-Brown Center On Aging, University of Kentucky, Lexington, KY, USA
| | - Björn Bauer
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Anika M S Hartz
- Sanders-Brown Center On Aging, University of Kentucky, Lexington, KY, USA.
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, 124 Healthy Kentucky Research Building 760 Press Avenue, Lexington, KY, 40508, USA.
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Teafatiller T, Perez O, Kitazawa M, Agrawal A, Subramanian VS. Nedd4-1 regulates human sodium-dependent vitamin C transporter-2 functional expression in neuronal and epithelial cells. J Nutr Biochem 2023; 120:109413. [PMID: 37423323 DOI: 10.1016/j.jnutbio.2023.109413] [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: 05/12/2023] [Revised: 06/12/2023] [Accepted: 07/05/2023] [Indexed: 07/11/2023]
Abstract
The ubiquitin-proteasomal pathway regulates the functional expression of many membrane transporters in a variety of cellular systems. Nothing is currently known about the role of ubiquitin E3 ligase, neural precursor cell-expressed developmentally down-regulated gene 4 (Nedd4-1) and the proteasomal degradation pathway in regulating human vitamin C transporter-2 (hSVCT2) in neuronal cells. hSVCT2 mediates the uptake of ascorbic acid (AA) and is the predominantly expressed vitamin C transporter isoform in neuronal systems. Therefore, we addressed this knowledge gap in our study. Analysis of mRNA revealed markedly higher expression of Nedd4-1 in neuronal samples than that of Nedd4-2. Interestingly, Nedd4-1 expression in the hippocampus was higher in patients with Alzheimer's disease (AD) and age-dependently increased in the J20 mouse model of AD. The interaction of Nedd4-1 and hSVCT2 was confirmed by coimmunoprecipitation and colocalization. While the coexpression of Nedd4-1 with hSVCT2 displayed a significant decrease in AA uptake, siRNA-mediated knockdown of Nedd4-1 expression up-regulated the AA uptake. Further, we mutated a classical Nedd4 protein interacting motif ("PPXY") within the hSVCT2 polypeptide and observed markedly decreased AA uptake due to the intracellular localization of the mutated hSVCT2. Also, we determined the role of the proteasomal degradation pathway in hSVCT2 functional expression in SH-SY5Y cells and the results indicated that the proteasomal inhibitor (MG132) significantly up-regulated the AA uptake and hSVCT2 protein expression level. Taken together, our findings show that the regulation of hSVCT2 functional expression is at least partly mediated by the Nedd4-1 dependent ubiquitination and proteasomal pathways.
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Affiliation(s)
- Trevor Teafatiller
- Department of Medicine, University of California, Irvine, California, USA
| | - Oasis Perez
- Department of Medicine, University of California, Irvine, California, USA
| | - Masashi Kitazawa
- Department of Environmental and Occupational Health, University of California, Irvine, California, USA
| | - Anshu Agrawal
- Department of Medicine, University of California, Irvine, California, USA
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5
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Schulz JA, Hartz AMS, Bauer B. ABCB1 and ABCG2 Regulation at the Blood-Brain Barrier: Potential New Targets to Improve Brain Drug Delivery. Pharmacol Rev 2023; 75:815-853. [PMID: 36973040 PMCID: PMC10441638 DOI: 10.1124/pharmrev.120.000025] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 03/10/2023] [Accepted: 03/10/2023] [Indexed: 03/29/2023] Open
Abstract
The drug efflux transporters ABCB1 and ABCG2 at the blood-brain barrier limit the delivery of drugs into the brain. Strategies to overcome ABCB1/ABCG2 have been largely unsuccessful, which poses a tremendous clinical problem to successfully treat central nervous system (CNS) diseases. Understanding basic transporter biology, including intracellular regulation mechanisms that control these transporters, is critical to solving this clinical problem.In this comprehensive review, we summarize current knowledge on signaling pathways that regulate ABCB1/ABCG2 at the blood-brain barrier. In Section I, we give a historical overview on blood-brain barrier research and introduce the role that ABCB1 and ABCG2 play in this context. In Section II, we summarize the most important strategies that have been tested to overcome the ABCB1/ABCG2 efflux system at the blood-brain barrier. In Section III, the main component of this review, we provide detailed information on the signaling pathways that have been identified to control ABCB1/ABCG2 at the blood-brain barrier and their potential clinical relevance. This is followed by Section IV, where we explain the clinical implications of ABCB1/ABCG2 regulation in the context of CNS disease. Lastly, in Section V, we conclude by highlighting examples of how transporter regulation could be targeted for therapeutic purposes in the clinic. SIGNIFICANCE STATEMENT: The ABCB1/ABCG2 drug efflux system at the blood-brain barrier poses a significant problem to successful drug delivery to the brain. The article reviews signaling pathways that regulate blood-brain barrier ABCB1/ABCG2 and could potentially be targeted for therapeutic purposes.
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Affiliation(s)
- Julia A Schulz
- Department of Pharmaceutical Sciences, College of Pharmacy (J.A.S., B.B.), Sanders-Brown Center on Aging and Department of Pharmacology and Nutritional Sciences, College of Medicine (A.M.S.H.), University of Kentucky, Lexington, Kentucky
| | - Anika M S Hartz
- Department of Pharmaceutical Sciences, College of Pharmacy (J.A.S., B.B.), Sanders-Brown Center on Aging and Department of Pharmacology and Nutritional Sciences, College of Medicine (A.M.S.H.), University of Kentucky, Lexington, Kentucky
| | - Björn Bauer
- Department of Pharmaceutical Sciences, College of Pharmacy (J.A.S., B.B.), Sanders-Brown Center on Aging and Department of Pharmacology and Nutritional Sciences, College of Medicine (A.M.S.H.), University of Kentucky, Lexington, Kentucky
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6
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Identification and Empiric Evaluation of New Inhibitors of the Multidrug Transporter P-Glycoprotein (ABCB1). Int J Mol Sci 2023; 24:ijms24065298. [PMID: 36982374 PMCID: PMC10049699 DOI: 10.3390/ijms24065298] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 02/24/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
The expression of the drug efflux pump ABCB1 correlates negatively with cancer survival, making the transporter an attractive target for therapeutic inhibition. In order to identify new inhibitors of ABCB1, we have exploited the cryo-EM structure of the protein to develop a pharmacophore model derived from the best docked conformations of a structurally diverse range of known inhibitors. The pharmacophore model was used to screen the Chembridge compound library. We identified six new potential inhibitors with distinct chemistry compared to the third-generation inhibitor tariquidar and with favourable lipophilic efficiency (LipE) and lipophilicity (CLogP) characteristics, suggesting oral bioavailability. These were evaluated experimentally for efficacy and potency using a fluorescent drug transport assay in live cells. The half-maximal inhibitory concentrations (IC50) of four of the compounds were in the low nanomolar range (1.35 to 26.4 nM). The two most promising compounds were also able to resensitise ABCB1-expressing cells to taxol. This study demonstrates the utility of cryo-electron microscopy structure determination for drug identification and design.
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Chai AB, Callaghan R, Gelissen IC. Regulation of P-Glycoprotein in the Brain. Int J Mol Sci 2022; 23:ijms232314667. [PMID: 36498995 PMCID: PMC9740459 DOI: 10.3390/ijms232314667] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/18/2022] [Accepted: 11/22/2022] [Indexed: 11/27/2022] Open
Abstract
Maintenance of the tightly regulated homeostatic environment of the brain is facilitated by the blood-brain barrier (BBB). P-glycoprotein (P-gp), an ATP-binding cassette transporter, is expressed on the luminal surface of the endothelial cells in the BBB, and actively exports a wide variety of substrates to limit exposure of the vulnerable brain environment to waste buildup and neurotoxic compounds. Downregulation of P-gp expression and activity at the BBB have been reported with ageing and in neurodegenerative diseases. Upregulation of P-gp at the BBB contributes to poor therapeutic outcomes due to altered pharmacokinetics of CNS-acting drugs. The regulation of P-gp is highly complex, but unravelling the mechanisms involved may help the development of novel and nuanced strategies to modulate P-gp expression for therapeutic benefit. This review summarises the current understanding of P-gp regulation in the brain, encompassing the transcriptional, post-transcriptional and post-translational mechanisms that have been identified to affect P-gp expression and transport activity.
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Affiliation(s)
- Amanda B. Chai
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2006, Australia
| | - Richard Callaghan
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Ingrid C. Gelissen
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2006, Australia
- Correspondence: ; Tel.: +61-2-8627-0357
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Taggi V, Riera Romo M, Piquette-Miller M, Meyer zu Schwabedissen HE, Neuhoff S. Transporter Regulation in Critical Protective Barriers: Focus on Brain and Placenta. Pharmaceutics 2022; 14:pharmaceutics14071376. [PMID: 35890272 PMCID: PMC9319476 DOI: 10.3390/pharmaceutics14071376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/14/2022] [Accepted: 06/24/2022] [Indexed: 01/06/2023] Open
Abstract
Drug transporters play an important role in the maintenance of chemical balance and homeostasis in different tissues. In addition to their physiological functions, they are crucial for the absorption, distribution, and elimination of many clinically important drugs, thereby impacting therapeutic efficacy and toxicity. Increasing evidence has demonstrated that infectious, metabolic, inflammatory, and neurodegenerative diseases alter the expression and function of drug transporters. However, the current knowledge on transporter regulation in critical protective barriers, such as the brain and placenta, is still limited and requires more research. For instance, while many studies have examined P-glycoprotein, it is evident that research on the regulation of highly expressed transporters in the blood–brain barrier and blood–placental barrier are lacking. The aim of this review is to summarize the currently available literature in order to better understand transporter regulation in these critical barriers.
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Affiliation(s)
- Valerio Taggi
- Biopharmacy, Department of Pharmaceutical Sciences, University of Basel, 4056 Basel, Switzerland; (V.T.); (H.E.M.z.S.)
| | - Mario Riera Romo
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada; (M.R.R.); (M.P.-M.)
| | - Micheline Piquette-Miller
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada; (M.R.R.); (M.P.-M.)
| | | | - Sibylle Neuhoff
- Certara UK Ltd., Simcyp Division, Sheffield S1 2BJ, UK
- Correspondence:
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9
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Meng Y, Qiu L, Zhang S, Han J. The emerging roles of E3 ubiquitin ligases in ovarian cancer chemoresistance. CANCER DRUG RESISTANCE (ALHAMBRA, CALIF.) 2022; 4:365-381. [PMID: 35582023 PMCID: PMC9019267 DOI: 10.20517/cdr.2020.115] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 01/13/2021] [Accepted: 01/18/2021] [Indexed: 12/24/2022]
Abstract
Epithelial cancer of the ovary exhibits the highest mortality rate of all gynecological malignancies in women today, since the disease is often diagnosed in advanced stages. While the treatment of cancer with specific chemical agents or drugs is the favored treatment regimen, chemotherapy resistance greatly impedes successful ovarian cancer chemotherapy. Thus, chemoresistance becomes one of the most critical clinical issues confronted when treating patients with ovarian cancer. Convincing evidence hints that dysregulation of E3 ubiquitin ligases is a key factor in the development and maintenance of ovarian cancer chemoresistance. This review outlines recent advancement in our understanding of the emerging roles of E3 ubiquitin ligases in ovarian cancer chemoresistance. We also highlight currently available inhibitors targeting E3 ligase activities and discuss their potential for clinical applications in treating chemoresistant ovarian cancer patients.
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Affiliation(s)
- Yang Meng
- Research Laboratory of Cancer Epigenetics and Genomics, Department of General Surgery, Frontiers Science Center for Disease-related Molecular Network, Cancer Center and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China.,Yang Meng and Lei Qiu equally contributed to this manuscript
| | - Lei Qiu
- Research Laboratory of Cancer Epigenetics and Genomics, Department of General Surgery, Frontiers Science Center for Disease-related Molecular Network, Cancer Center and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China.,Yang Meng and Lei Qiu equally contributed to this manuscript
| | - Su Zhang
- Research Laboratory of Cancer Epigenetics and Genomics, Department of General Surgery, Frontiers Science Center for Disease-related Molecular Network, Cancer Center and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Junhong Han
- Research Laboratory of Cancer Epigenetics and Genomics, Department of General Surgery, Frontiers Science Center for Disease-related Molecular Network, Cancer Center and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041, China
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10
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The Role of NEDD4 E3 Ubiquitin–Protein Ligases in Parkinson’s Disease. Genes (Basel) 2022; 13:genes13030513. [PMID: 35328067 PMCID: PMC8950476 DOI: 10.3390/genes13030513] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 03/03/2022] [Indexed: 01/25/2023] Open
Abstract
Parkinson’s disease (PD) is a debilitating neurodegenerative disease that causes a great clinical burden. However, its exact molecular pathologies are not fully understood. Whilst there are a number of avenues for research into slowing, halting, or reversing PD, one central idea is to enhance the clearance of the proposed aetiological protein, oligomeric α-synuclein. Oligomeric α-synuclein is the main constituent protein in Lewy bodies and neurites and is considered neurotoxic. Multiple E3 ubiquitin-protein ligases, including the NEDD4 (neural precursor cell expressed developmentally downregulated protein 4) family, parkin, SIAH (mammalian homologues of Drosophila seven in absentia), CHIP (carboxy-terminus of Hsc70 interacting protein), and SCFFXBL5 SCF ubiquitin ligase assembled by the S-phase kinase-associated protein (SKP1), cullin-1 (Cul1), a zinc-binding RING finger protein, and the F-box domain/Leucine-rich repeat protein 5-containing protein FBXL5), have been shown to be able to ubiquitinate α-synuclein, influencing its subsequent degradation via the proteasome or lysosome. Here, we explore the link between NEDD4 ligases and PD, which is not only via α-synuclein but further strengthened by several additional substrates and interaction partners. Some members of the NEDD4 family of ligases are thought to crosstalk even with PD-related genes and proteins found to be mutated in familial forms of PD. Mutations in NEDD4 family genes have not been observed in PD patients, most likely because of their essential survival function during development. Following further in vivo studies, it has been thought that NEDD4 ligases may be viable therapeutic targets in PD. NEDD4 family members could clear toxic proteins, enhancing cell survival and slowing disease progression, or might diminish beneficial proteins, reducing cell survival and accelerating disease progression. Here, we review studies to date on the expression and function of NEDD4 ubiquitin ligases in the brain and their possible impact on PD pathology.
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The Ubiquitin E3 Ligase Nedd4 Regulates the Expression and Amyloid-β Peptide Export Activity of P-Glycoprotein. Int J Mol Sci 2022; 23:ijms23031019. [PMID: 35162941 PMCID: PMC8834788 DOI: 10.3390/ijms23031019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/12/2022] [Accepted: 01/16/2022] [Indexed: 02/04/2023] Open
Abstract
The ATP-binding cassette transporter, P-glycoprotein (P-gp), has been demonstrated to facilitate the clearance of amyloid-beta (Aβ) peptides, exporting the neurotoxic entity out of neurons and out of the brain via the blood–brain barrier. However, its expression and function diminish with age and in Alzheimer’s disease. P-gp is known to undergo ubiquitination, a post-translational modification that results in internalisation and/or degradation of the protein. NEDD4-1 is a ubiquitin E3 ligase that has previously been shown to ubiquitinate P-gp and reduce its cell surface expression. However, whether this effect translates into altered P-gp activity remains to be determined. siRNA was used to knockdown the expression of Nedd4 in CHO-APP cells. Western blot analysis confirmed that absence of Nedd4 was associated with increased P-gp protein expression. This was accompanied by increased transport activity, as shown by export of the P-gp substrate calcein-AM, as well as enhanced secretion of Aβ peptides, as shown by ELISA. These results implicate Nedd4 in the regulation of P-gp, and highlight a potential approach for restoring or augmenting P-gp expression and function to facilitate Aβ clearance from the brain.
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Zou T, Zeng C, Qu J, Yan X, Lin Z. Rutaecarpine Increases Anticancer Drug Sensitivity in Drug-Resistant Cells through MARCH8-Dependent ABCB1 Degradation. Biomedicines 2021; 9:1143. [PMID: 34572328 PMCID: PMC8466742 DOI: 10.3390/biomedicines9091143] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/28/2021] [Accepted: 08/30/2021] [Indexed: 12/24/2022] Open
Abstract
The overexpression of adenosine triphosphate (ATP)-binding cassette (ABC) subfamily B member 1 (ABCB1; P-glycoprotein; MDR1) in some types of cancer cells is one of the mechanisms responsible for the development of multidrug resistance (MDR), which leads to the failure of chemotherapy. Therefore, it is important to inhibit the activity or reduce the expression level of ABCB1 to maintain an effective intracellular level of chemotherapeutic drugs. In this study, we found that rutaecarpine, a bioactive alkaloid isolated from Evodia Rutaecarpa, has the capacity to reverse ABCB1-mediated MDR. Our data indicated that the reversal effect of rutaecarpine was related to the attenuation of the protein level of ABCB1. Mechanistically, we demonstrated that ABCB1 is a newly discovered substrate of E3 ubiquitin ligase membrane-associated RING-CH 8 (MARCH8). MARCH8 can interact with ABCB1 and promote its ubiquitination and degradation. In short, rutaecarpine increased the degradation of ABCB1 protein by upregulating the protein level of MARCH8, thereby antagonizing ABCB1-mediated MDR. Notably, the treatment of rutaecarpine combined with other anticancer drugs exhibits a therapeutic effect on transplanted tumors. Therefore, our study provides a potential chemotherapeutic strategy of co-administrating rutaecarpine with other conventional chemotherapeutic agents to overcome MDR and improve therapeutic effect.
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Affiliation(s)
- Tingting Zou
- School of Life Sciences, Chongqing University, Chongqing 401331, China; (T.Z.); (C.Z.); (J.Q.)
| | - Cheng Zeng
- School of Life Sciences, Chongqing University, Chongqing 401331, China; (T.Z.); (C.Z.); (J.Q.)
| | - Junyan Qu
- School of Life Sciences, Chongqing University, Chongqing 401331, China; (T.Z.); (C.Z.); (J.Q.)
| | - Xiaohua Yan
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Nanchang University, Nanchang 330006, China
| | - Zhenghong Lin
- School of Life Sciences, Chongqing University, Chongqing 401331, China; (T.Z.); (C.Z.); (J.Q.)
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ABCB1 Does Not Require the Side-Chain Hydrogen-Bond Donors Gln 347, Gln 725, Gln 990 to Confer Cellular Resistance to the Anticancer Drug Taxol. Int J Mol Sci 2021; 22:ijms22168561. [PMID: 34445264 PMCID: PMC8395328 DOI: 10.3390/ijms22168561] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/14/2021] [Accepted: 07/28/2021] [Indexed: 01/11/2023] Open
Abstract
The multidrug efflux transporter ABCB1 is clinically important for drug absorption and distribution and can be a determinant of chemotherapy failure. Recent structure data shows that three glutamines donate hydrogen bonds to coordinate taxol in the drug binding pocket. This is consistent with earlier drug structure-activity relationships that implicated the importance of hydrogen bonds in drug recognition by ABCB1. By replacing the glutamines with alanines we have tested whether any, or all, of Gln347, Gln725, and Gln990 are important for the transport of three different drug classes. Flow cytometric transport assays show that Q347A and Q990A act synergistically to reduce transport of Calcein-AM, BODIPY-verapamil, and OREGON GREEN-taxol bisacetate but the magnitude of the effect was dependent on the test drug and no combination of mutations completely abrogated function. Surprisingly, Q725A mutants generally improved transport of Calcein-AM and BODIPY-verapamil, suggesting that engagement of the wild-type Gln725 in a hydrogen bond is inhibitory for the transport mechanism. To test transport of unmodified taxol, stable expression of Q347/725A and the triple mutant was engineered and shown to confer equivalent resistance to the drug as the wild-type transporter, further indicating that none of these potential hydrogen bonds between transporter and transport substrate are critical for the function of ABCB1. The implications of the data for plasticity of the drug binding pocket are discussed.
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Ding Y, Zhong Y, Baldeshwiler A, Abner EL, Bauer B, Hartz AMS. Protecting P-glycoprotein at the blood-brain barrier from degradation in an Alzheimer's disease mouse model. Fluids Barriers CNS 2021; 18:10. [PMID: 33676539 PMCID: PMC7937299 DOI: 10.1186/s12987-021-00245-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Accepted: 02/25/2021] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Failure to clear Aβ from the brain is partly responsible for Aβ brain accumulation in Alzheimer's disease (AD). A critical protein for clearing Aβ across the blood-brain barrier is the efflux transporter P-glycoprotein (P-gp). In AD, P-gp levels are reduced, which contributes to impaired Aβ brain clearance. However, the mechanism responsible for decreased P-gp levels is poorly understood and there are no strategies available to protect P-gp. We previously demonstrated in isolated brain capillaries ex vivo that human Aβ40 (hAβ40) triggers P-gp degradation by activating the ubiquitin-proteasome pathway. In this pathway, hAβ40 initiates P-gp ubiquitination, leading to internalization and proteasomal degradation of P-gp, which then results in decreased P-gp protein expression and transport activity levels. Here, we extend this line of research and present results from an in vivo study using a transgenic mouse model of AD (human amyloid precursor protein (hAPP)-overexpressing mice; Tg2576). METHODS In our study, hAPP mice were treated with vehicle, nocodazole (NCZ, microtubule inhibitor to block P-gp internalization), or a combination of NCZ and the P-gp inhibitor cyclosporin A (CSA). We determined P-gp protein expression and transport activity levels in isolated mouse brain capillaries and Aβ levels in plasma and brain tissue. RESULTS Treating hAPP mice with 5 mg/kg NCZ for 14 days increased P-gp levels to levels found in WT mice. Consistent with this, P-gp-mediated hAβ42 transport in brain capillaries was increased in NCZ-treated hAPP mice compared to untreated hAPP mice. Importantly, NCZ treatment significantly lowered hAβ40 and hAβ42 brain levels in hAPP mice, whereas hAβ40 and hAβ42 levels in plasma remained unchanged. CONCLUSIONS These findings provide in vivo evidence that microtubule inhibition maintains P-gp protein expression and transport activity levels, which in turn helps to lower hAβ brain levels in hAPP mice. Thus, protecting P-gp at the blood-brain barrier may provide a novel therapeutic strategy for AD and other Aβ-based pathologies.
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Affiliation(s)
- Yujie Ding
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA
| | - Yu Zhong
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA
| | - Andrea Baldeshwiler
- Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, University of Minnesota, Duluth, Minnesota, 55812, USA
| | - Erin L Abner
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA
- Department of Epidemiology, College of Public Health, University of Kentucky, Lexington, KY, 40536, USA
| | - Björn Bauer
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, 40536, USA
| | - Anika M S Hartz
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, 40536, USA.
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, 40536, USA.
- University of Kentucky Sanders-Brown Center on Aging, 800 S Limestone, Lexington, KY, 40536, USA.
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15
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McCarty MF, DiNicolantonio JJ, Lerner A. A Fundamental Role for Oxidants and Intracellular Calcium Signals in Alzheimer's Pathogenesis-And How a Comprehensive Antioxidant Strategy May Aid Prevention of This Disorder. Int J Mol Sci 2021; 22:2140. [PMID: 33669995 PMCID: PMC7926325 DOI: 10.3390/ijms22042140] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 12/13/2022] Open
Abstract
Oxidative stress and increased cytoplasmic calcium are key mediators of the detrimental effects on neuronal function and survival in Alzheimer's disease (AD). Pathways whereby these perturbations arise, and then prevent dendritic spine formation, promote tau hyperphosphorylation, further amplify amyloid β generation, and induce neuronal apoptosis, are described. A comprehensive program of nutraceutical supplementation, comprised of the NADPH oxidase inhibitor phycocyanobilin, phase two inducers, the mitochondrial antioxidant astaxanthin, and the glutathione precursor N-acetylcysteine, may have important potential for antagonizing the toxic effects of amyloid β on neurons and thereby aiding prevention of AD. Moreover, nutraceutical antioxidant strategies may oppose the adverse impact of amyloid β oligomers on astrocyte clearance of glutamate, and on the ability of brain capillaries to export amyloid β monomers/oligomers from the brain. Antioxidants, docosahexaenoic acid (DHA), and vitamin D, have potential for suppressing microglial production of interleukin-1β, which potentiates the neurotoxicity of amyloid β. Epidemiology suggests that a health-promoting lifestyle, incorporating a prudent diet, regular vigorous exercise, and other feasible measures, can cut the high risk for AD among the elderly by up to 60%. Conceivably, complementing such lifestyle measures with long-term adherence to the sort of nutraceutical regimen outlined here may drive down risk for AD even further.
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Affiliation(s)
| | | | - Aaron Lerner
- Chaim Sheba Medical Center, The Zabludowicz Research Center for Autoimmune Diseases, Tel Hashomer 5262000, Israel
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16
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Mammalian ABCG-transporters, sterols and lipids: To bind perchance to transport? Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1866:158860. [PMID: 33309976 DOI: 10.1016/j.bbalip.2020.158860] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 11/15/2020] [Accepted: 12/08/2020] [Indexed: 02/08/2023]
Abstract
Members of the ATP binding cassette (ABC) transporter family perform a critical function in maintaining lipid homeostasis in cells as well as the transport of drugs. In this review, we provide an update on the ABCG-transporter subfamily member proteins, which include the homodimers ABCG1, ABCG2 and ABCG4 as well as the heterodimeric complex formed between ABCG5 and ABCG8. This review focusses on progress made in this field of research with respect to their function in health and disease and the recognised transporter substrates. We also provide an update on post-translational regulation, including by transporter substrates, and well as the involvement of microRNA as regulators of transporter expression and activity. In addition, we describe progress made in identifying structural elements that have been recognised as important for transport activity. We furthermore discuss the role of lipids such as cholesterol on the transport function of ABCG2, traditionally thought of as a drug transporter, and provide a model of potential cholesterol binding sites for ABCG2.
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17
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Bauer B, Renfro JL, Karnaky KJ, Masereeuw R, Fricker G, Cannon RE, Hartz AMS. David S. Miller: Scientist, Mentor, Friend-a tribute and thank you. Fluids Barriers CNS 2020; 17:56. [PMID: 32928243 PMCID: PMC7491162 DOI: 10.1186/s12987-020-00220-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 09/09/2020] [Indexed: 11/25/2022] Open
Abstract
David S. Miller was Acting Scientific Director of the Division of Intramural Research at the National Institute of Environmental Health Sciences, National Institutes of Health, and Head of the Intracellular Regulation Group in the Laboratory of Toxicology and Pharmacology before he retired in 2016. David received his Ph.D. in biochemistry from the University of Maine in 1973. David was a Group Leader at the Michigan Cancer Foundation before joining the NIEHS in 1985. His research covered a wide range from renal excretory transport mechanisms to regulation of transporters at the blood–CSF and blood–brain barriers, from fish, amphibians and birds to mammals. David was an outstanding scientist with irresistible enthusiasm for science and an incredible ability to think outside the box while being an exceptional mentor and friend.
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Affiliation(s)
- Björn Bauer
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 333 Sanders-Brown Center on Aging, 800 S Limestone, Lexington, KY, 40536-0230, USA.
| | - J Larry Renfro
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Karl J Karnaky
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA
| | - Rosalinde Masereeuw
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands
| | - Gert Fricker
- Institute of Pharmacy and Molecular Biotechnology, University of Heidelberg, 69120, Heidelberg, Germany
| | - Ron E Cannon
- Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - Anika M S Hartz
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA.,Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
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18
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Luo X, Teng QX, Dong JY, Yang DH, Wang M, Dessie W, Qin JJ, Lei ZN, Wang JQ, Qin Z, Chen ZS. Antimicrobial Peptide Reverses ABCB1-Mediated Chemotherapeutic Drug Resistance. Front Pharmacol 2020; 11:1208. [PMID: 32903706 PMCID: PMC7438908 DOI: 10.3389/fphar.2020.01208] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 07/24/2020] [Indexed: 12/12/2022] Open
Abstract
Multidrug resistance (MDR) of tumor cells to chemotherapeutic agents is the main reason for the failure of cancer chemotherapy. Overexpression of ABCB1 transporter that actively pumps various drugs out of the cells has been considered a major contributing factor for MDR. Over the past decade, many antimicrobial peptides with antitumor activity have been identified or synthesized, and some antitumor peptides have entered the clinical practice. In this study, we report that peptide HX-12C has the effect of reversing ABCB1-mediated chemotherapy resistance. In ABCB1-overexpressing cells, nontoxic dose of peptide HX-12C inhibited drug resistance and increased the effective intracellular concentration of paclitaxel and other ABCB1 substrate drugs. The mechanism study showed that peptide HX-12C stimulated ABCB1 ATPase activity without changing the expression level and localization patterns of ABCB1. Molecular docking predicted the binding modes between peptide HX-12C and ABCB1. Overall, we found that peptide HX-12C reverses ABCB1-mediated MDR through interacting with ABCB1 and blocking its function without affecting the transporter's expression and cellular localization. Our findings suggest that this antimicrobial peptide may be used as a novel prospective cancer therapeutic strategy in combination with conventional anticancer agents.
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Affiliation(s)
- Xiaofang Luo
- Research Center of Biochemical Engineering Technology, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, China
| | - Qiu-Xu Teng
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John’s University, Queens, NY, United States
| | - Jin-Yun Dong
- Institute of Cancer and Basic Medicine, Chinese Academy of Sciences, Cancer Hospital of the University of Chinese Academy of Sciences, Zhejiang Cancer Hospital, Hangzhou, China
| | - Dong-Hua Yang
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John’s University, Queens, NY, United States
| | - Meifeng Wang
- Research Center of Biochemical Engineering Technology, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, China
| | - Wubliker Dessie
- Research Center of Biochemical Engineering Technology, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, China
| | - Jiang-Jiang Qin
- Institute of Cancer and Basic Medicine, Chinese Academy of Sciences, Cancer Hospital of the University of Chinese Academy of Sciences, Zhejiang Cancer Hospital, Hangzhou, China
| | - Zi-Ning Lei
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John’s University, Queens, NY, United States
| | - Jing-Quan Wang
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John’s University, Queens, NY, United States
| | - Zuodong Qin
- Research Center of Biochemical Engineering Technology, College of Chemistry and Bioengineering, Hunan University of Science and Engineering, Yongzhou, China
| | - Zhe-Sheng Chen
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John’s University, Queens, NY, United States
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19
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Wang ZW, Hu X, Ye M, Lin M, Chu M, Shen X. NEDD4 E3 ligase: Functions and mechanism in human cancer. Semin Cancer Biol 2020; 67:92-101. [PMID: 32171886 DOI: 10.1016/j.semcancer.2020.03.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 03/03/2020] [Accepted: 03/07/2020] [Indexed: 12/11/2022]
Abstract
A growing amount of evidence indicates that the neuronally expressed developmentally downregulated 4 (NEDD4, also known as NEDD4-1) E3 ligase plays a critical role in a variety of cellular processes via the ubiquitination-mediated degradation of multiple substrates. The abnormal regulation of NEDD4 protein has been implicated in cancer development and progression. In this review article, we briefly delineate the downstream substrates and upstream regulators of NEDD4, which are involved in carcinogenesis. Moreover, we succinctly elucidate the functions of NEDD4 protein in tumorigenesis and progression, including cell proliferation, apoptosis, cell cycle, migration, invasion, epithelial mesenchymal transition (EMT), cancer stem cells, and drug resistance. The findings regarding NEDD4 functions are further supported by knockout mouse models and human tumor tissue studies. This review could provide a promising and optimum anticancer therapeutic strategy via targeting the NEDD4 protein.
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Affiliation(s)
- Zhi-Wei Wang
- Center of Scientific Research, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China; Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
| | - Xiaoli Hu
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Miaomiao Ye
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Min Lin
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Man Chu
- Center of Scientific Research, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Xian Shen
- Department of Gastrointestinal Surgery, the Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China.
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20
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The many substrates and functions of NEDD4-1. Cell Death Dis 2019; 10:904. [PMID: 31787758 PMCID: PMC6885513 DOI: 10.1038/s41419-019-2142-8] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/24/2019] [Accepted: 11/12/2019] [Indexed: 01/08/2023]
Abstract
Tumorigenesis, tumor growth, and prognosis are highly related to gene alterations and post-translational modifications (PTMs). Ubiquitination is a critical PTM that governs practically all aspects of cellular function. An increasing number of studies show that E3 ubiquitin ligases (E3s) are important enzymes in the process of ubiquitination that primarily determine substrate specificity and thus need to be tightly controlled. Among E3s, neural precursor cell expressed developmentally downregulated 4-1 (NEDD4-1) has been shown to play a critical role in modulating the proliferation, migration, and invasion of cancer cells and the sensitivity of cancer cells to anticancer therapies via regulating multiple substrates. This review discusses some significant discoveries on NEDD4-1 substrates and the signaling pathways in which NEDD4-1 participates. In addition, we introduce the latest potential therapeutic strategies that inhibit or activate NEDD4-1 activity using small molecules. NEDD4-1 likely acts as a novel drug target or diagnostic marker in the battle against cancer.
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21
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Amyloid β-Induced Upregulation of Na v1.6 Underlies Neuronal Hyperactivity in Tg2576 Alzheimer's Disease Mouse Model. Sci Rep 2019; 9:13592. [PMID: 31537873 PMCID: PMC6753212 DOI: 10.1038/s41598-019-50018-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 07/31/2019] [Indexed: 12/19/2022] Open
Abstract
Hyperexcitability and alterations in neuronal networks contribute to cognitive impairment in Alzheimer’s Disease (AD). Voltage-gated sodium channels (NaV), which are crucial for regulating neuronal excitability, have been implicated in AD-related hippocampal hyperactivity and higher incidence of spontaneous non-convulsive seizures. Here, we show by using primary hippocampal neurons exposed to amyloid-β1–42 (Aβ1–42) oligomers and from Tg2576 mouse embryos, that the selective upregulation of NaV1.6 subtype contributes to membrane depolarization and to the increase of spike frequency, thereby resulting in neuronal hyperexcitability. Interestingly, we also found that NaV1.6 overexpression is responsible for the aberrant neuronal activity observed in hippocampal slices from 3-month-old Tg2576 mice. These findings identify the NaV1.6 channels as a determinant of the hippocampal neuronal hyperexcitability induced by Aβ1–42 oligomers. The selective blockade of NaV1.6 overexpression and/or hyperactivity might therefore offer a new potential therapeutic approach to counteract early hippocampal hyperexcitability and subsequent cognitive deficits in the early stages of AD.
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22
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Hartz AMS, Zhong Y, Shen AN, Abner EL, Bauer B. Preventing P-gp Ubiquitination Lowers Aβ Brain Levels in an Alzheimer's Disease Mouse Model. Front Aging Neurosci 2018; 10:186. [PMID: 29997495 PMCID: PMC6028735 DOI: 10.3389/fnagi.2018.00186] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 06/05/2018] [Indexed: 12/22/2022] Open
Abstract
One characteristic of Alzheimer's disease (AD) is excessive accumulation of amyloid-β (Aβ) in the brain. Aβ brain accumulation is, in part, due to a reduction in Aβ clearance from the brain across the blood-brain barrier. One key element that contributes to Aβ brain clearance is P-glycoprotein (P-gp) that transports Aβ from brain to blood. In AD, P-gp protein expression and transport activity levels are significantly reduced, which impairs Aβ brain clearance. The mechanism responsible for reduced P-gp expression and activity levels is poorly understood. We recently demonstrated that Aβ40 triggers P-gp degradation through the ubiquitin-proteasome pathway. Consistent with these data, we show here that ubiquitinated P-gp levels in brain capillaries isolated from brain samples of AD patients are increased compared to capillaries isolated from brain tissue of cognitive normal individuals. We extended this line of research to in vivo studies using transgenic human amyloid precursor protein (hAPP)-overexpressing mice (Tg2576) that were treated with PYR41, a cell-permeable, irreversible inhibitor of the ubiquitin-activating enzyme E1. Our data show that inhibiting P-gp ubiquitination protects the transporter from degradation, and immunoprecipitation experiments confirmed that PYR41 prevented P-gp ubiquitination. We further found that PYR41 treatment prevented reduction of P-gp protein expression and transport activity levels and substantially lowered Aβ brain levels in hAPP mice. Together, our findings provide in vivo proof that the ubiquitin-proteasome system mediates reduction of blood-brain barrier P-gp in AD and that inhibiting P-gp ubiquitination prevents P-gp degradation and lowers Aβ brain levels. Thus, targeting the ubiquitin-proteasome system may provide a novel therapeutic approach to protect blood-brain barrier P-gp from degradation in AD and other Aβ-based pathologies.
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Affiliation(s)
- Anika M S Hartz
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States.,Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, United States
| | - Yu Zhong
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - Andrew N Shen
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - Erin L Abner
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - Björn Bauer
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, United States
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23
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Abstract
Newly synthesized transmembrane proteins undergo a series of steps to ensure that only the required amount of correctly folded protein is localized to the membrane. The regulation of protein quality and its abundance at the membrane are often controlled by ubiquitination, a multistep enzymatic process that results in the attachment of ubiquitin, or chains of ubiquitin to the target protein. Protein ubiquitination acts as a signal for sorting, trafficking, and the removal of membrane proteins via endocytosis, a process through which multiple ubiquitin ligases are known to specifically regulate the functions of a number of ion channels, transporters, and signaling receptors. Endocytic removal of these proteins through ubiquitin-dependent endocytosis provides a way to rapidly downregulate the physiological outcomes, and defects in such controls are directly linked to human pathologies. Recent evidence suggests that ubiquitination is also involved in the shedding of membranes and associated proteins as extracellular vesicles, thereby not only controlling the cell surface levels of some membrane proteins, but also their potential transport to neighboring cells. In this review, we summarize the mechanisms and functions of ubiquitination of membrane proteins and provide specific examples of ubiquitin-dependent regulation of membrane proteins.
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Affiliation(s)
- Natalie Foot
- Centre for Cancer Biology, University of South Australia, Adelaide, Australia
| | - Tanya Henshall
- Centre for Cancer Biology, University of South Australia, Adelaide, Australia
| | - Sharad Kumar
- Centre for Cancer Biology, University of South Australia, Adelaide, Australia
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24
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Aβ40 Reduces P-Glycoprotein at the Blood-Brain Barrier through the Ubiquitin-Proteasome Pathway. J Neurosci 2016; 36:1930-41. [PMID: 26865616 DOI: 10.1523/jneurosci.0350-15.2016] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Failure to clear amyloid-β (Aβ) from the brain is in part responsible for Aβ brain accumulation in Alzheimer's disease (AD). A critical protein for clearing Aβ across the blood-brain barrier is the efflux transporter P-glycoprotein (P-gp) in the luminal plasma membrane of the brain capillary endothelium. P-gp is reduced at the blood-brain barrier in AD, which has been shown to be associated with Aβ brain accumulation. However, the mechanism responsible for P-gp reduction in AD is not well understood. Here we focused on identifying critical mechanistic steps involved in reducing P-gp in AD. We exposed isolated rat brain capillaries to 100 nm Aβ40, Aβ40, aggregated Aβ40, and Aβ42. We observed that only Aβ40 triggered reduction of P-gp protein expression and transport activity levels; this occurred in a dose- and time-dependent manner. To identify the steps involved in Aβ-mediated P-gp reduction, we inhibited protein ubiquitination, protein trafficking, and the ubiquitin-proteasome system, and monitored P-gp protein expression, transport activity, and P-gp-ubiquitin levels. Thus, exposing brain capillaries to Aβ40 triggers ubiquitination, internalization, and proteasomal degradation of P-gp. These findings may provide potential therapeutic targets within the blood-brain barrier to limit P-gp degradation in AD and improve Aβ brain clearance. SIGNIFICANCE STATEMENT The mechanism reducing blood-brain barrier P-glycoprotein (P-gp) in Alzheimer's disease is poorly understood. In the present study, we focused on defining this mechanism. We demonstrate that Aβ40 drives P-gp ubiquitination, internalization, and proteasome-dependent degradation, reducing P-gp protein expression and transport activity in isolated brain capillaries. These findings may provide potential therapeutic avenues within the blood-brain barrier to limit P-gp degradation in Alzheimer's disease and improve Aβ brain clearance.
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25
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Aleidi SM, Howe V, Sharpe LJ, Yang A, Rao G, Brown AJ, Gelissen IC. The E3 ubiquitin ligases, HUWE1 and NEDD4-1, are involved in the post-translational regulation of the ABCG1 and ABCG4 lipid transporters. J Biol Chem 2015; 290:24604-13. [PMID: 26296893 DOI: 10.1074/jbc.m115.675579] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Indexed: 11/06/2022] Open
Abstract
The ATP-binding cassette transporter ABCG1 has an essential role in cellular cholesterol homeostasis, and dysregulation has been associated with a number of high burden diseases. Previous studies reported that ABCG1 is ubiquitinated and degraded via the ubiquitin proteasome system. However, so far the molecular mechanism, including the identity of any of the rate-limiting ubiquitination enzymes, or E3 ligases, is unknown. Using liquid chromatography mass spectrometry, we identified two HECT domain E3 ligases associated with ABCG1, named HUWE1 (HECT, UBA, and WWE domain containing 1, E3 ubiquitin protein ligase) and NEDD4-1 (Neural precursor cell-expressed developmentally down regulated gene 4), of which the latter is the founding member of the NEDD4 family of ubiquitin ligases. Silencing both HUWE1 and NEDD4-1 in cells overexpressing human ABCG1 significantly increased levels of the ABCG1 monomeric and dimeric protein forms, however ABCA1 protein expression was unaffected. In addition, ligase silencing increased ABCG1-mediated cholesterol export to HDL in cells overexpressing the transporter as well as in THP-1 macrophages. Reciprocally, overexpression of both ligases resulted in a significant reduction in protein levels of both the ABCG1 monomeric and dimeric forms. Like ABCG1, ABCG4 protein levels and cholesterol export activity were significantly increased after silencing both HUWE1 and NEDD4-1 in cells overexpressing this closely related ABC half-transporter. In summary, we have identified for the first time two E3 ligases that are fundamental enzymes in the post-translational regulation of ABCG1 and ABCG4 protein levels and cellular cholesterol export activity.
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Affiliation(s)
- Shereen M Aleidi
- From the Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006 and
| | - Vicky Howe
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney NSW 2052 Australia
| | - Laura J Sharpe
- From the Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006 and School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney NSW 2052 Australia
| | - Alryel Yang
- From the Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006 and
| | - Geetha Rao
- From the Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006 and
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney NSW 2052 Australia
| | - Ingrid C Gelissen
- From the Faculty of Pharmacy, The University of Sydney, Sydney NSW 2006 and
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