1
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Grønbæk-Thygesen M, Voutsinos V, Johansson KE, Schulze TK, Cagiada M, Pedersen L, Clausen L, Nariya S, Powell RL, Stein A, Fowler DM, Lindorff-Larsen K, Hartmann-Petersen R. Deep mutational scanning reveals a correlation between degradation and toxicity of thousands of aspartoacylase variants. Nat Commun 2024; 15:4026. [PMID: 38740822 DOI: 10.1038/s41467-024-48481-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 05/02/2024] [Indexed: 05/16/2024] Open
Abstract
Unstable proteins are prone to form non-native interactions with other proteins and thereby may become toxic. To mitigate this, destabilized proteins are targeted by the protein quality control network. Here we present systematic studies of the cytosolic aspartoacylase, ASPA, where variants are linked to Canavan disease, a lethal neurological disorder. We determine the abundance of 6152 of the 6260 ( ~ 98%) possible single amino acid substitutions and nonsense ASPA variants in human cells. Most low abundance variants are degraded through the ubiquitin-proteasome pathway and become toxic upon prolonged expression. The data correlates with predicted changes in thermodynamic stability, evolutionary conservation, and separate disease-linked variants from benign variants. Mapping of degradation signals (degrons) shows that these are often buried and the C-terminal region functions as a degron. The data can be used to interpret Canavan disease variants and provide insight into the relationship between protein stability, degradation and cell fitness.
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Affiliation(s)
- Martin Grønbæk-Thygesen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Vasileios Voutsinos
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Kristoffer E Johansson
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Thea K Schulze
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Matteo Cagiada
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Line Pedersen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Lene Clausen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Snehal Nariya
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Rachel L Powell
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Amelie Stein
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Douglas M Fowler
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
- Department of Bioengineering, University of Washington, Seattle, WA, USA.
| | - Kresten Lindorff-Larsen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
| | - Rasmus Hartmann-Petersen
- Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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2
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Chai J, Long X, Wu P, Wang J, Wu X, Tu Z, Wei M, Guo Z, Zhang T, Chen L. Lactobacillus sp. participated in the adaptation of Rongchang piglets to cold stress. VET MED-CZECH 2023; 68:392-402. [PMID: 38028206 PMCID: PMC10666660 DOI: 10.17221/54/2023-vetmed] [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: 05/14/2023] [Accepted: 09/19/2023] [Indexed: 12/01/2023] Open
Abstract
Rongchang piglets were easily induced to cold stress and diarrhoea in the winter when raised in an open hog house. However, they also gradually recovered under mid-cold stress. Other studies have suggested gut microbiome might be involved in the host energy metabolism to relieve stress. To study how to adapt Rongchang piglets to cold stress by gut microbiome, thirty Rongchang piglets were randomly divided into a mild cold stress group and a control group for 30 consecutive days. The findings revealed that the piglets had low growth performance and a high diarrhoea rate and mortality rate during the first half of the cold treatment, but subsequently stabilised. The level of cortisol (COR) also displayed a similar trend. In the mild cold stress group, the relative abundance of Muribaculaceae significantly increased on day 15, and the predominant bacterial on day 30 was Lactobacillus sp. Our results indicated that the Rongchang piglet's production performance and health were impaired at the start of the mild cold stress. However, as time passed, the body could progressively adapt to the low temperature, and Lactobacillus sp. participated in this process. This study provides new insight into how to alleviate health damage caused by cold stress.
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Affiliation(s)
- Jie Chai
- Chongqing Academy of Animal Science, Chong Qing, Rongchang, P.R. China
- National Center of Technology Innovation for Pigs, Chong Qing, Rongchang, P.R. China
| | - Xi Long
- Chongqing Academy of Animal Science, Chong Qing, Rongchang, P.R. China
- National Center of Technology Innovation for Pigs, Chong Qing, Rongchang, P.R. China
| | - Pingxian Wu
- Chongqing Academy of Animal Science, Chong Qing, Rongchang, P.R. China
- National Center of Technology Innovation for Pigs, Chong Qing, Rongchang, P.R. China
| | - Jinyong Wang
- Chongqing Academy of Animal Science, Chong Qing, Rongchang, P.R. China
- National Center of Technology Innovation for Pigs, Chong Qing, Rongchang, P.R. China
| | - Xiaoqian Wu
- Chongqing Academy of Animal Science, Chong Qing, Rongchang, P.R. China
- National Center of Technology Innovation for Pigs, Chong Qing, Rongchang, P.R. China
| | - Zhi Tu
- Chongqing Academy of Animal Science, Chong Qing, Rongchang, P.R. China
- National Center of Technology Innovation for Pigs, Chong Qing, Rongchang, P.R. China
| | - Minghong Wei
- Chongqing Academy of Animal Science, Chong Qing, Rongchang, P.R. China
- National Center of Technology Innovation for Pigs, Chong Qing, Rongchang, P.R. China
| | - Zongyi Guo
- Chongqing Academy of Animal Science, Chong Qing, Rongchang, P.R. China
- National Center of Technology Innovation for Pigs, Chong Qing, Rongchang, P.R. China
| | - Tinghuan Zhang
- Chongqing Academy of Animal Science, Chong Qing, Rongchang, P.R. China
- National Center of Technology Innovation for Pigs, Chong Qing, Rongchang, P.R. China
| | - Li Chen
- Chongqing Academy of Animal Science, Chong Qing, Rongchang, P.R. China
- National Center of Technology Innovation for Pigs, Chong Qing, Rongchang, P.R. China
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3
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Almaghrbi H, Elkardawy R, Udhaya Kumar S, Kuttikrishnan S, Abunada T, Kashyap MK, Ahmad A, Uddin S, George Priya Doss C, Zayed H. Analysis of signaling cascades from myeloma cells treated with pristimerin. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 134:147-174. [PMID: 36858733 DOI: 10.1016/bs.apcsb.2022.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Multiple myeloma (MM) is the 2nd most frequently diagnosed blood cancer after non-Hodgkin's lymphoma. The present study aimed to identify the differentially expressed genes (DEGs) between the control and pristimerin-treated MM cell lines. We examined the GSE14011 microarray dataset and screened DEGs with GEO2R statistical tool using the inbuilt limma package. We used a bioinformatics pipeline to identify the differential networks, signaling cascades, and the survival of the hub genes. We implemented two different enrichment analysis including ClueGO and Metacore™, to get accurate annotation for most significant DEGs. We screened the most significant 408 DEGs from the dataset based on p-values and logFC values. Using protein network analysis, we found the genes UBC, HSP90AB1, HSPH1, HSPA1B, HSPA1L, HSPA6, HSPD1, DNAJB1, HSPE1, DNAJC10, BAG3, and DNAJC7 had higher node degree distribution. In contrast, the functional annotation provided that the DEGs were predominantly enriched in B-cell receptor signaling, unfolded protein response, positive regulation of phagocytosis, HSP70, and HSP40-dependent folding, and ubiquitin-proteasomal proteolysis. Using network algorithms, and comparing enrichment analysis, we found the hub genes enriched were INHBE, UBC, HSPA1A, HSP90AB1, IKBKB, and BAG3. These DEGs were further validated with overall survival and gene expression analysis between the tumor and control groups. Finally, pristimerin effects were validated independently in a cell line model consisting of IM9 and U266 MM cells. Pristimerin induced in vitro cytotoxicity in MM cells in a dose-dependent manner. Pristimerin inhibited NF-κB, induced accumulation of ubiquitinated proteins and inhibited HSP60 in the validation of bioinformatics findings, while pristimerin-induced caspase-3 and PARP cleavage confirmed cell death. Taken together, we found that the identified DEGs were strongly associated with the apoptosis induced in MM cell lines due to pristimerin treatment, and combinatorial therapy derived from pristimerin could act as novel anti-myeloma multifunctional agents.
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Affiliation(s)
- Heba Almaghrbi
- Department of Biomedical Sciences, College of Health and Sciences, QU Health, Qatar University, Doha, Qatar
| | - Rehab Elkardawy
- Department of Biomedical Sciences, College of Health and Sciences, QU Health, Qatar University, Doha, Qatar
| | - S Udhaya Kumar
- Laboratory of Integrative Genomics, Department of Integrative Biology, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Shilpa Kuttikrishnan
- Translational Research Institute & Dermatology Institute, Academic Health System, Hamad Medical Corporation, Doha, Qatar; College of Pharmacy, QU Health, Qatar University, Doha, Qatar
| | - Taghreed Abunada
- Department of Biomedical Sciences, College of Health and Sciences, QU Health, Qatar University, Doha, Qatar
| | - Manoj Kumar Kashyap
- Amity Stem Cell Institute, Amity Medical School, Amity University Haryana, Panchgaon (Manesar), Gurugram, India
| | - Aamir Ahmad
- Translational Research Institute & Dermatology Institute, Academic Health System, Hamad Medical Corporation, Doha, Qatar
| | - Shahab Uddin
- Translational Research Institute & Dermatology Institute, Academic Health System, Hamad Medical Corporation, Doha, Qatar
| | - C George Priya Doss
- Laboratory of Integrative Genomics, Department of Integrative Biology, School of Biosciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Hatem Zayed
- Department of Biomedical Sciences, College of Health and Sciences, QU Health, Qatar University, Doha, Qatar.
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4
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Hodos RA, Strub MD, Ramachandran S, Meleshkevitch EA, Boudko DY, Bridges RJ, Dudley JT, McCray PB. Integrative chemogenomic analysis identifies small molecules that partially rescue ΔF508-CFTR for cystic fibrosis. CPT-PHARMACOMETRICS & SYSTEMS PHARMACOLOGY 2021; 10:500-510. [PMID: 33934548 PMCID: PMC8129714 DOI: 10.1002/psp4.12626] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/15/2021] [Accepted: 03/22/2021] [Indexed: 12/14/2022]
Abstract
Rare diseases affect 10% of the first‐world population, yet over 95% lack even a single pharmaceutical treatment. In the present age of information, we need ways to leverage our vast data and knowledge to streamline therapeutic development and lessen this gap. Here, we develop and implement an innovative informatic approach to identify therapeutic molecules, using the Connectivity Map and LINCS L1000 databases and disease‐associated transcriptional signatures and pathways. We apply this to cystic fibrosis (CF), the most common genetic disease in people of northern European ancestry leading to chronic lung disease and reduced lifespan. We selected and tested 120 small molecules in a CF cell line, finding 8 with activity, and confirmed 3 in primary CF airway epithelia. Although chemically diverse, the transcriptional profiles of the hits suggest a common mechanism associated with the unfolded protein response and/or TNFα signaling. This study highlights the power of informatics to help identify new therapies and reveal mechanistic insights while moving beyond target‐centric drug discovery.
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Affiliation(s)
- Rachel A Hodos
- Institute for Next Generation Healthcare, Mount Sinai School of Medicine, New York, NY, USA.,Courant Institute for Mathematical Sciences, New York University, New York, NY, USA
| | - Matthew D Strub
- Department of Pediatrics, University of Iowa, Carver College of Medicine, Iowa City, IA, USA.,Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA, USA
| | | | - Ella A Meleshkevitch
- Department of Physiology and Biophysics, Rosalind Franklin University, North Chicago, IL, USA
| | - Dmitri Y Boudko
- Department of Physiology and Biophysics, Rosalind Franklin University, North Chicago, IL, USA
| | - Robert J Bridges
- Department of Physiology and Biophysics, Rosalind Franklin University, North Chicago, IL, USA
| | - Joel T Dudley
- Institute for Next Generation Healthcare, Mount Sinai School of Medicine, New York, NY, USA
| | - Paul B McCray
- Department of Pediatrics, University of Iowa, Carver College of Medicine, Iowa City, IA, USA.,Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA, USA
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5
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Oommen D, Kizhakkedath P, Jawabri AA, Varghese DS, Ali BR. Proteostasis Regulation in the Endoplasmic Reticulum: An Emerging Theme in the Molecular Pathology and Therapeutic Management of Familial Hypercholesterolemia. Front Genet 2020; 11:570355. [PMID: 33173538 PMCID: PMC7538668 DOI: 10.3389/fgene.2020.570355] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 08/31/2020] [Indexed: 02/05/2023] Open
Abstract
Familial hypercholesterolemia (FH) is an autosomal genetic disease characterized by high serum low-density lipoprotein (LDL) content leading to premature coronary artery disease. The main genetic and molecular causes of FH are mutations in low-density lipoprotein receptor gene (LDLR) resulting in the non-clearance of LDL from the blood by hepatocytes and consequently the formation of plaques. LDLR is synthesized and glycosylated in the endoplasmic reticulum (ER) and then transported to the plasma membrane via Golgi. It is estimated that more than 50% of reported FH-causing mutations in LDLR result in misfolded proteins that are transport-defective and hence retained in ER. ER accumulation of misfolded proteins causes ER-stress and activates unfolded protein response (UPR). UPR aids protein folding, blocks further protein synthesis, and eliminates misfolded proteins via ER-associated degradation (ERAD) to alleviate ER stress. Various studies demonstrated that ER-retained LDLR mutants are subjected to ERAD. Interestingly, chemical chaperones and genetic or pharmacological inhibition of ERAD have been reported to rescue the transport defective mutant LDLR alleles from ERAD and restore their ER-Golgi transport resulting in the expression of functional plasma membrane LDLR. This suggests the possibility of pharmacological modulation of proteostasis in the ER as a therapeutic strategy for FH. In this review, we picture a detailed analysis of UPR and the ERAD processes activated by ER-retained LDLR mutants associated with FH. In addition, we discuss and critically evaluate the potential role of chemical chaperones and ERAD modulators in the therapeutic management of FH.
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Affiliation(s)
- Deepu Oommen
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Praseetha Kizhakkedath
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Aseel A Jawabri
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Divya Saro Varghese
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Bassam R Ali
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates.,Department of Pathology, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates.,Zayed Center for Health Sciences, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
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6
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Wang Y, Du Y, Luo L, Hu P, Yang G, Li T, Han X, Ma A, Wang T. Alterations of Nedd4-2-binding capacity in PY-motif of Na V 1.5 channel underlie long QT syndrome and Brugada syndrome. Acta Physiol (Oxf) 2020; 229:e13438. [PMID: 31900993 DOI: 10.1111/apha.13438] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/19/2019] [Accepted: 12/29/2019] [Indexed: 12/13/2022]
Abstract
AIMS Pathogenic variants of the SCN5A gene can cause Brugada syndrome (BrS) and long QT syndrome (LQTS), which predispose individuals to potentially fatal ventricular arrhythmias and sudden cardiac death. SCN5A encodes the NaV 1.5 protein, the pore forming α-subunit of the voltage-dependent cardiac Na+ channel. Using a WW domain, the E3 ubiquitin ligase Nedd4-2 binds to the PY-motif ([L/P]PxY) within the C-terminus of NaV 1.5, which results in decreased protein expression and current through NaV 1.5 ubiquitination. Here, we investigate the role of E3 ubiquitin ligase Nedd4-2-mediated NaV 1.5 degradation in the pathological mechanisms of the BrS-associated variant SCN5A-p.L1239P and LQTS-associated variant SCN5A-p.Y1977N. METHODS AND RESULTS Using a combination of molecular biology, biochemical and electrophysiological approaches, we examined the expression, function and Nedd4-2 interactions of SCN5A-p.L1239P and SCN5A-p.Y1977N. SCN5A-p.L1239P is characterized as a loss-of-function, whereas SCN5A-p.Y1977N is a gain-of-function variant of the NaV 1.5 channel. Sequence alignment shows that BrS-associated SCN5A-p.L1239P has a new Nedd4-2-binding site (from LLxY to LPxY). This new Nedd4-2-binding site increases the interaction between NaV 1.5 and Nedd4-2, enhancing ubiquitination and degradation of the NaV 1.5 channel. Disruption of the new Nedd4-2-binding site of SCN5A-p.L1239P restores NaV 1.5 expression and function. However, the LQTS-associated SCN5A-p.Y1977N disrupts the usual Nedd4-2-binding site (from PPxY to PPxN). This decreases NaV 1.5-Nedd4-2 interaction, preventing ubiquitination and degradation of NaV 1.5 channels. CONCLUSIONS Our data suggest that the PY-motif plays an essential role in modifying the expression/function of NaV 1.5 channels through Nedd4-2-mediated ubiquitination. Alterations of NaV 1.5-Nedd4-2 interaction represent a novel pathological mechanism for NaV 1.5 channel diseases caused by SCN5A variants.
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Affiliation(s)
- Ya Wang
- Department of Cardiovascular Medicine First Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi P. R. China
| | - Yuan Du
- Department of Cardiovascular Medicine First Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi P. R. China
| | - Ling Luo
- Department of Cardiovascular Medicine First Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi P. R. China
| | - Peijing Hu
- Department of Cardiovascular Medicine Second Affiliated Hospital of Xi'an Medical College Xi'an Shaanxi P. R. China
| | - Guodong Yang
- Department of Cardiovascular Medicine First Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi P. R. China
| | - Tao Li
- Department of Cardiovascular Medicine First Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi P. R. China
| | - Xiu Han
- Department of Cardiovascular Medicine First Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi P. R. China
| | - Aiqun Ma
- Department of Cardiovascular Medicine First Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi P. R. China
- Key Laboratory of Molecular Cardiology Xi'an Shaanxi P. R. China
- Key Laboratory of Environment and Genes Related to Diseases Xi'an Jiaotong University Ministry of Education Xi'an Shaanxi P. R. China
| | - Tingzhong Wang
- Department of Cardiovascular Medicine First Affiliated Hospital of Xi'an Jiaotong University Xi'an Shaanxi P. R. China
- Key Laboratory of Molecular Cardiology Xi'an Shaanxi P. R. China
- Key Laboratory of Environment and Genes Related to Diseases Xi'an Jiaotong University Ministry of Education Xi'an Shaanxi P. R. China
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7
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Shutdown of ER-associated degradation pathway rescues functions of mutant iduronate 2-sulfatase linked to mucopolysaccharidosis type II. Cell Death Dis 2018; 9:808. [PMID: 30042467 PMCID: PMC6057917 DOI: 10.1038/s41419-018-0871-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 07/04/2018] [Accepted: 07/10/2018] [Indexed: 01/04/2023]
Abstract
Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a devastating progressive disease caused by mutations in the iduronate 2-sulfatase (IDS) gene. IDS is one of the sulfatase enzymes required for lysosomal degradation of glycosaminoglycans. Mutant proteins linked to diseases are often prone to misfolding. These misfolded proteins accumulate in the endoplasmic reticulum (ER) and are degraded by the ubiquitin–proteasome pathway (ER-associated degradation (ERAD)). The decreased enzyme activities of IDS mutants may be due to accelerated degradation by ERAD. However, intracellular dynamics including degradation of IDS mutants is unexplored. In this report, we examined biochemical and biological characteristics of wild-type (WT) IDS and IDS mutants expressed in HeLa cells. IDS was shown to be glycosylated in the ER and Golgi apparatus and proteolytically cleaved to generate the mature forms in the Golgi apparatus. The mature WT IDS was translocated to the lysosome. In contrast, all IDS mutants we examined were found to accumulate in the ER and could not efficiently translocate to the lysosome. Accumulated IDS mutants in the ER were ubiquitinated by ERAD-related ubiquitin E3 ligase HRD1 followed by degradation via ERAD. Suppressed degradation of ‘attenuated’ mutant A85T IDS (the late-onset form of MPS II) by inhibiting ERAD components improved translocation to the lysosome and its activities. Our novel findings provide alternative targets to current principal therapies for MPS II. These perspectives provide a potenti al framework to develop fundamental therapeutic strategies and agents.
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8
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Morita M, Matsumoto S, Sato A, Inoue K, Kostsin DG, Yamazaki K, Kawaguchi K, Shimozawa N, Kemp S, Wanders RJ, Kojima H, Okabe T, Imanaka T. Stability of the ABCD1 Protein with a Missense Mutation: A Novel Approach to Finding Therapeutic Compounds for X-Linked Adrenoleukodystrophy. JIMD Rep 2018; 44:23-31. [PMID: 29926352 DOI: 10.1007/8904_2018_118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 03/30/2018] [Accepted: 05/22/2018] [Indexed: 12/04/2022] Open
Abstract
Mutations in the ABCD1 gene that encodes peroxisomal ABCD1 protein cause X-linked adrenoleukodystrophy (X-ALD), a rare neurodegenerative disorder. More than 70% of the patient fibroblasts with this missense mutation display either a lack or reduction of the ABCD1 protein because of posttranslational degradation. In this study, we analyzed the stability of the missense mutant ABCD1 proteins (p.A616T, p.R617H, and p.R660W) in X-ALD fibroblasts and found that the mutant ABCD1 protein p.A616T has the capacity to recover its function by incubating at low temperature. In the case of such a mutation, chemical compounds that stabilize mutant ABCD1 proteins could be therapeutic candidates. Here, we prepared CHO cell lines stably expressing ABCD1 proteins with a missense mutation in fusion with green fluorescent protein (GFP) at the C-terminal. The stability of each mutant ABCD1-GFP in CHO cells was similar to the corresponding mutant ABCD1 protein in X-ALD fibroblasts. Furthermore, it is of interest that the GFP at the C-terminal was degraded together with the mutant ABCD1 protein. These findings prompted us to use CHO cells expressing mutant ABCD1-GFP for a screening of chemical compounds that can stabilize the mutant ABCD1 protein. We established a fluorescence-based assay method for the screening of chemical libraries in an effort to find compounds that stabilize mutant ABCD1 proteins. The work presented here provides a novel approach to finding therapeutic compounds for X-ALD patients with missense mutations.
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Affiliation(s)
- Masashi Morita
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
| | - Shun Matsumoto
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Airi Sato
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Kengo Inoue
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Dzmitry G Kostsin
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.,Institute of Biophysics and Cell Engineering, National Academy of Sciences of Belarus, Minsk, Belarus.,Establishment of Health "National Anti-Doping Laboratory", Lyasny, Belarus
| | - Kozue Yamazaki
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Kosuke Kawaguchi
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan
| | - Nobuyuki Shimozawa
- Division of Genomic Research, Life Science Research Center, Gifu University, Gifu, Japan
| | - Stephan Kemp
- Laboratory of Genetic Metabolic Diseases, Academic Centre, Amsterdam, The Netherlands
| | - Ronald J Wanders
- Laboratory of Genetic Metabolic Diseases, Academic Centre, Amsterdam, The Netherlands
| | - Hirotatsu Kojima
- Drug Discovery Initiative, The University of Tokyo, Tokyo, Japan
| | - Takayoshi Okabe
- Drug Discovery Initiative, The University of Tokyo, Tokyo, Japan
| | - Tsuneo Imanaka
- Department of Biological Chemistry, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.,Faculty of Pharmaceutical Sciences, Hiroshima International University, Hiroshima, Japan
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9
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Adnan H, Zhang Z, Park HJ, Tailor C, Che C, Kamani M, Spitalny G, Binnington B, Lingwood C. Endoplasmic Reticulum-Targeted Subunit Toxins Provide a New Approach to Rescue Misfolded Mutant Proteins and Revert Cell Models of Genetic Diseases. PLoS One 2016; 11:e0166948. [PMID: 27935997 PMCID: PMC5147855 DOI: 10.1371/journal.pone.0166948] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Accepted: 11/06/2016] [Indexed: 01/08/2023] Open
Abstract
Many germ line diseases stem from a relatively minor disturbance in mutant protein endoplasmic reticulum (ER) 3D assembly. Chaperones are recruited which, on failure to correct folding, sort the mutant for retrotranslocation and cytosolic proteasomal degradation (ER-associated degradation-ERAD), to initiate/exacerbate deficiency-disease symptoms. Several bacterial (and plant) subunit toxins, retrograde transport to the ER after initial cell surface receptor binding/internalization. The A subunit has evolved to mimic a misfolded protein and hijack the ERAD membrane translocon (dislocon), to effect cytosolic access and cytopathology. We show such toxins compete for ERAD to rescue endogenous misfolded proteins. Cholera toxin or verotoxin (Shiga toxin) containing genetically inactivated (± an N-terminal polyleucine tail) A subunit can, within 2–4 hrs, temporarily increase F508delCFTR protein, the major cystic fibrosis (CF) mutant (5-10x), F508delCFTR Golgi maturation (<10x), cell surface expression (20x) and chloride transport (2x) in F508del CFTR transfected cells and patient-derived F508delCFTR bronchiolar epithelia, without apparent cytopathology. These toxoids also increase glucocerobrosidase (GCC) in N370SGCC Gaucher Disease fibroblasts (3x), another ERAD–exacerbated misfiling disease. We identify a new, potentially benign approach to the treatment of certain genetic protein misfolding diseases.
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Affiliation(s)
- Humaira Adnan
- Division of Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Zhenbo Zhang
- Division of Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Hyun-Joo Park
- Division of Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Chetankumar Tailor
- Division of Cell Biology, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Clare Che
- Division of Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Mustafa Kamani
- Division of Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario, Canada
| | | | - Beth Binnington
- Division of Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Clifford Lingwood
- Division of Molecular Structure and Function, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Ontario, Canada
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Ontario, Canada
- * E-mail:
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10
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Veltman M, Stolarczyk M, Radzioch D, Wojewodka G, De Sanctis JB, Dik WA, Dzyubachyk O, Oravecz T, de Kleer I, Scholte BJ. Correction of lung inflammation in a F508del CFTR murine cystic fibrosis model by the sphingosine-1-phosphate lyase inhibitor LX2931. Am J Physiol Lung Cell Mol Physiol 2016; 311:L1000-L1014. [PMID: 27663991 DOI: 10.1152/ajplung.00298.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 09/19/2016] [Indexed: 01/08/2023] Open
Abstract
Progressive lung disease with early onset is the main cause of mortality and morbidity in cystic fibrosis patients. Here we report a reduction of sphingosine-1-phosphate (S1P) in the lung of unchallenged Cftrtm1EUR F508del CFTR mutant mice. This correlates with enhanced infiltration by inducible nitric oxide synthase (iNOS)-expressing granulocytes, B cells, and T cells. Furthermore, the ratio of macrophage-derived dendritic cells (MoDC) to conventional dendritic cells (cDC) is higher in mutant mouse lung, consistent with unprovoked inflammation. Oral application of a S1P lyase inhibitor (LX2931) increases S1P levels in mutant mouse tissues. This normalizes the lung MoDC/cDC ratio and reduces B and T cell counts. Lung granulocytes are enhanced, but iNOS expression is reduced in this population. Although lung LyC6+ monocytes are enhanced by LX2931, they apparently do not differentiate to MoDC and macrophages. After challenge with bacterial toxins (LPS-fMLP) we observe enhanced levels of proinflammatory cytokines TNF-α, KC, IFNγ, and IL-12 and the inducible mucin MUC5AC in mutant mouse lung, evidence of deficient resolution of inflammation. LX2931 does not prevent transient inflammation or goblet cell hyperplasia after challenge, but it reduces MUC5AC and proinflammatory cytokine levels toward normal values. We conclude that lung pathology in homozygous mice expressing murine F508del CFTR, which represents the most frequent mutation in CF patients, is characterized by abnormal behavior of infiltrating myeloid cells and delayed resolution of induced inflammation. This phenotype can be partially corrected by a S1P lyase inhibitor, providing a rationale for therapeutic targeting of the S1P signaling pathway in CF patients.
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Affiliation(s)
- Mieke Veltman
- Cell Biology, Erasmus MC, Rotterdam, The Netherlands
| | | | - Danuta Radzioch
- Departments of Medicine and Human Genetics, McGill University, Montreal, Canada
| | - Gabriella Wojewodka
- Departments of Medicine and Human Genetics, McGill University, Montreal, Canada
| | - Juan B De Sanctis
- Faculty of Medicine. Universidad Central de Venezuela, Institute of Immunology, Caracas, Venezuela
| | - Willem A Dik
- Immunology, Erasmus MC, Rotterdam, The Netherlands
| | - Oleh Dzyubachyk
- Department of Radiology, Division of Image Processing, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Ismé de Kleer
- Department of Pediatrics, Division of Respiratory Medicine, Erasmus MC, Rotterdam, The Netherlands; and.,Laboratory of Pulmonary Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Bob J Scholte
- Cell Biology, Erasmus MC, Rotterdam, The Netherlands;
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11
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Palma AG, Galizia L, Kotsias BA, Marino GI. CFTR channel in oocytes from Xenopus laevis and its regulation by xShroom1 protein. Pflugers Arch 2016; 468:871-80. [PMID: 26888038 DOI: 10.1007/s00424-016-1800-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/18/2016] [Accepted: 02/10/2016] [Indexed: 01/24/2023]
Abstract
Shroom is a family of related proteins linked to the actin cytoskeleton. xShroom1 is constitutively expressed in Xenopus laevis oocytes, and it is required for the expression of the epithelial sodium channel (ENaC). As there is a close relationship between ENaC and the cystic fibrosis transmembrane regulator (CFTR), we examined the action of xShroom1 on CFTR expression and activity. Biotinylation was used to measure CFTR surface expression, and currents were registered with voltage clamp when stimulated with forskolin and 3-isobutyl-1-methylxanthine. Oocytes were coinjected with CFTR complementary RNAs (cRNAs) and xShroom1 sense or antisense oligonucleotides. We observed an increment in CFTR currents and CFTR surface expression in oocytes coinjected with CFTR and xShroom1 antisense oligonucleotides. MG-132, a proteasome inhibitor, did not prevent the increment in currents when xShroom1 was suppressed by antisense oligonucleotides. In addition, we inhibited the delivery of newly synthesized proteins to the plasma membrane with BFA and we found that the half-life of plasma membrane CFTR was prolonged when coinjected with the xShroom1 antisense oligonucleotides. Chloroquine, an inhibitor of the late endosome/lysosome, did not significantly increase CFTR currents when xShroom1 expression was inhibited. The higher expression of CFTR when xShroom1 is suppressed is in concordance with the functional studies suggesting that the suppression of the xShroom1 protein resulted in an increment in CFTR currents by promoting the increase of the half-life of CFTR in the plasma membrane. The role of xShroom1 in regulating CFTR expression could be relevant in the understanding of the channel malfunction in several diseases.
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Affiliation(s)
- Alejandra G Palma
- Laboratorio de Canales Iónicos, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires, IDIM-CONICET, C. de Malvinas 3150, 1427, Buenos Aires, Argentina
| | - Luciano Galizia
- Laboratorio de Canales Iónicos, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires, IDIM-CONICET, C. de Malvinas 3150, 1427, Buenos Aires, Argentina
| | - Basilio A Kotsias
- Laboratorio de Canales Iónicos, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires, IDIM-CONICET, C. de Malvinas 3150, 1427, Buenos Aires, Argentina
| | - Gabriela I Marino
- Laboratorio de Canales Iónicos, Instituto de Investigaciones Médicas Alfredo Lanari, Universidad de Buenos Aires, IDIM-CONICET, C. de Malvinas 3150, 1427, Buenos Aires, Argentina.
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12
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Zhang Y, O'Brien WG, Zhao Z, Lee CC. 5'-adenosine monophosphate mediated cooling treatment enhances ΔF508-Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) stability in vivo. J Biomed Sci 2015; 22:72. [PMID: 26335336 PMCID: PMC4559075 DOI: 10.1186/s12929-015-0178-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 08/20/2015] [Indexed: 12/26/2022] Open
Abstract
Background Gene mutations that produce misprocessed proteins are linked to many human disorders. Interestingly, some misprocessed proteins retained their biological function when stabilized by low temperature treatment of cultured cells in vitro. Here we investigate whether low temperature treatment in vivo can rescue misfolded proteins by applying 5’-AMP mediated whole body cooling to a Cystic Fibrosis (CF) mouse model carrying a mutant cystic fibrosis transmembrane conductance regulator (CFTR) with a deletion of the phenylalanine residue in position 508 (ΔF508-CFTR). Low temperature treatment of cultured cells was previously shown to be able to alleviate the processing defect of ΔF508-CFTR, enhancing its plasma membrane localization and its function in mediating chloride ion transport. Results Here, we report that whole body cooling enhanced the retention of ΔF508-CFTR in intestinal epithelial cells. Functional analysis based on β-adrenergic dependent salivary secretion and post-natal mortality rate revealed a moderate but significant improvement in treated compared with untreated CF mice. Conclusions Our findings demonstrate that temperature sensitive processing of mutant proteins can be responsive to low temperature treatment in vivo.
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Affiliation(s)
- Yueqiang Zhang
- Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - William G O'Brien
- Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Zhaoyang Zhao
- Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Cheng Chi Lee
- Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA.
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Jai Y, Shah K, Bridges RJ, Bradbury NA. Evidence against resveratrol as a viable therapy for the rescue of defective ΔF508 CFTR. Biochim Biophys Acta Gen Subj 2015; 1850:2377-84. [PMID: 26342647 DOI: 10.1016/j.bbagen.2015.08.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/10/2015] [Accepted: 08/31/2015] [Indexed: 01/23/2023]
Abstract
BACKGROUND Resveratrol, a natural phenolic compound, has been reported to rescue mutant ΔF508 CFTR in expression systems and primary epithelial cells. Although this implies a therapeutic benefit to patients with CF, investigations were performed using resveratrol concentrations greatly in excess of those achievable in plasma. We evaluated the efficacy of resveratrol as a CFTR corrector in relevant primary airway cells, using physiologically achievable resveratrol concentrations. METHODS Cells expressing wt or ΔF508 CFTR were exposed to chronic or acute resveratrol. CFTR mRNA and protein expression were monitored. The effects of resveratrol on primary ΔF508 human airway cells were evaluated by equivalent current analysis using modified Ussing chambers. RESULTS Consistent with previously published data in heterologous expression systems, high doses of resveratrol increased CFTR expression; however physiologically relevant concentrations were without effect. In contrast to heterologous expression systems, resveratrol was unable to increase mutant CFTR channel activity in primary airway cells. Elevated amiloride-sensitive currents, indicative of sodium transport and characteristically elevated in CF airway cells, were also unaffected by resveratrol. CONCLUSIONS High concentrations of resveratrol can increase CFTR mRNA and protein in some cell types. In addition, acute resveratrol exposure can stimulate CFTR mediated chloride secretion, probably by increasing cellular cAMP levels. Resveratrol at physiologically achievable levels yielded no benefit in primary ΔF508 airway cells, either in terms of amiloride-sensitive currents of CFTR currents. GENERAL SIGNIFICANCE Taken together, our results do not support the use of resveratrol supplements as a therapy for patients with cystic fibrosis. It is possible that further modifications of the resveratrol backbone would yield a more efficacious compound.
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Affiliation(s)
- Ying Jai
- Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Kalpit Shah
- Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Robert J Bridges
- Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Neil A Bradbury
- Department of Physiology and Biophysics, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA.
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Genetic Inhibition Of The Ubiquitin Ligase Rnf5 Attenuates Phenotypes Associated To F508del Cystic Fibrosis Mutation. Sci Rep 2015; 5:12138. [PMID: 26183966 PMCID: PMC4505316 DOI: 10.1038/srep12138] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 06/17/2015] [Indexed: 12/28/2022] Open
Abstract
Cystic fibrosis (CF) is caused by mutations in the CFTR chloride channel. Deletion of phenylalanine 508 (F508del), the most frequent CF mutation, impairs CFTR trafficking and gating. F508del-CFTR mistrafficking may be corrected by acting directly on mutant CFTR itself or by modulating expression/activity of CFTR-interacting proteins, that may thus represent potential drug targets. To evaluate possible candidates for F508del-CFTR rescue, we screened a siRNA library targeting known CFTR interactors. Our analysis identified RNF5 as a protein whose inhibition promoted significant F508del-CFTR rescue and displayed an additive effect with the investigational drug VX-809. Significantly, RNF5 loss in F508del-CFTR transgenic animals ameliorated intestinal malabsorption and concomitantly led to an increase in CFTR activity in intestinal epithelial cells. In addition, we found that RNF5 is differentially expressed in human bronchial epithelia from CF vs. control patients. Our results identify RNF5 as a target for therapeutic modalities to antagonize mutant CFTR proteins.
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Dhooghe B, Bouckaert C, Capron A, Wallemacq P, Leal T, Noel S. Resveratrol increases F508del-CFTR dependent salivary secretion in cystic fibrosis mice. Biol Open 2015; 4:929-36. [PMID: 26092868 PMCID: PMC4571083 DOI: 10.1242/bio.010967] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cystic fibrosis (CF) is a fatal genetic disease associated with widespread exocrine gland dysfunction. Studies have suggested activating effects of resveratrol, a naturally-occurring polyphenol compound with antioxidant and anti-inflammatory properties, on CF transmembrane conductance regulator (CFTR) protein function. We assayed, in F508del-CFTR homozygous (CF) and in wild-type mice, the effect of resveratrol on salivary secretion in basal conditions, in response to inhibition by atropine (basal β-adrenergic-dependent component) and to stimulation by isoprenaline (CFTR-dependent component). Both components of the salivary secretion were smaller in CF mice than in controls. Two hours after intraperitoneal administration of resveratrol (50 mg/kg) dissolved in DMSO, the compound was detected in salivary glands. As in both CF and in wild-type mice, DMSO alone increased the response to isoprenaline in males but not in females, the effect of resveratrol was only measured in females. In wild-type mice, isoprenaline increased secretion by more than half. In CF mice, resveratrol rescued the response to isoprenaline, eliciting a 2.5-fold increase of β-adrenergic-stimulated secretion. We conclude that the salivary secretion assay is suitable to test DMSO-soluble CFTR modulators in female mice. We show that resveratrol applied in vivo to mice reaches salivary glands and increases β-adrenergic secretion. Immunolabelling of CFTR in human bronchial epithelial cells suggests that the effect is associated with increased CFTR protein expression. Our data support the view that resveratrol is beneficial for treating CF. The salivary secretion assay has a potential application to test efficacy of novel CF therapies.
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Affiliation(s)
- Barbara Dhooghe
- Louvain Centre for Toxicology and Applied Pharmacology, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels B1200, Belgium
| | - Charlotte Bouckaert
- Louvain Centre for Toxicology and Applied Pharmacology, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels B1200, Belgium
| | - Arnaud Capron
- Clinical Chemistry Department, Cliniques Universitaires St. Luc, Université Catholique de Louvain, Brussels B1200, Belgium
| | - Pierre Wallemacq
- Clinical Chemistry Department, Cliniques Universitaires St. Luc, Université Catholique de Louvain, Brussels B1200, Belgium
| | - Teresinha Leal
- Louvain Centre for Toxicology and Applied Pharmacology, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels B1200, Belgium
| | - Sabrina Noel
- Louvain Centre for Toxicology and Applied Pharmacology, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels B1200, Belgium
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Abstract
PURPOSE OF REVIEW The field of cystic fibrosis (CF) continues to evolve at a fast pace thanks to novel observations that have enabled deeper understanding of the disease pathophysiology. Parallel groundbreaking developments in innovative therapies permit, for the first time, distinct disease modification. RECENT FINDINGS This review highlights important discoveries in fluid homeostasis and mucus secretion in CF that further informs the pathophysiology of the airway disease that characterizes CF. In addition, current concepts and novel paradigms, such as 'theratypes' and 'CF transmembrane conductance regulator chaperome', which will be important for the continued development of disease modifying therapies, are reviewed. SUMMARY The rate of progress in the field continues to accelerate with new knowledge informing the development of innovative therapies. This has already led to tangible substantial and unprecedented clinical benefit for selected subsets of the CF patient population. In the years ahead, further knowledge acquisition may motivate the extension of these benefits to the larger population of people with CF.
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KCNC3(R420H), a K(+) channel mutation causative in spinocerebellar ataxia 13 displays aberrant intracellular trafficking. Neurobiol Dis 2014; 71:270-9. [PMID: 25152487 DOI: 10.1016/j.nbd.2014.08.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 07/29/2014] [Accepted: 08/13/2014] [Indexed: 12/23/2022] Open
Abstract
Spinocerebellar ataxia 13 (SCA13) is an autosomal dominant disease resulting from mutations in KCNC3 (Kv3.3), a voltage-gated potassium channel. The KCNC3(R420H) mutation was first identified as causative for SCA13 in a four-generation Filipino kindred with over 20 affected individuals. Electrophysiological analyses in oocytes previously showed that this mutation did not lead to a functional channel and displayed a dominant negative phenotype. In an effort to identify the molecular basis of this allelic form of SCA13, we first determined that human KCNC3(WT) and KCNC3(R420H) display disparate post-translational modifications, and the mutant protein has reduced complex glycan adducts. Immunohistochemical analyses demonstrated that KCNC3(R420H) was not properly trafficking to the plasma membrane and surface biotinylation demonstrated that KCNC3(R420H) exhibited only 24% as much surface expression as KCNC3(WT). KCNC3(R420H) trafficked through the ER but was retained in the Golgi. KCNC3(R420H) expression results in altered Golgi and cellular morphology. Electron microscopy of KCNC3(R420H) localization further supports retention in the Golgi. These results are specific to the KCNC3(R420H) allele and provide new insight into the molecular basis of disease manifestation in SCA13.
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Minogue PJ, Beyer EC, Berthoud VM. A connexin50 mutant, CX50fs, that causes cataracts is unstable, but is rescued by a proteasomal inhibitor. J Biol Chem 2013; 288:20427-34. [PMID: 23720739 DOI: 10.1074/jbc.m113.452847] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The mechanisms by which mutant connexins lead to disease are diverse, including those of connexin50 (CX50) encoded by the GJA8 gene. We investigated the cellular and functional behavior of CX50fs, a mutant CX50 that has a frameshift after amino acid 255 and causes recessive congenital cataracts. Cellular levels of CX50fs were much lower than those of wild type CX50 in stably transfected HeLa cells. Whereas CX50 localized at distinct gap junction plaques and supported extensive intercellular transfer of Neurobiotin, CX50fs gap junctions were rare, and their support of Neurobiotin transfer was reduced by >90%. After inhibition of new protein synthesis with cycloheximide, CX50fs disappeared much more rapidly than CX50, suggesting increased degradation of the mutant. Treatment of cells with epoxomicin (a proteasomal inhibitor) led to a dramatic increase in CX50fs levels and in the abundance of gap junctions. Epoxomicin treatment also rescued intercellular transfer of Neurobiotin to levels similar to those in cells expressing the wild type protein. Treatment with eeyarestatin I (an inhibitor of p97-dependent protein degradation) resulted in many abundant slowly migrating CX50 and CX50fs bands consistent with polyubiquitination of the proteins. These results demonstrate that the CX50fs mutant is rapidly degraded by endoplasmic reticulum-associated degradation in mammalian cells. This accelerated degradation reduces the abundance of gap junctions and the extent of intercellular communication, potentially explaining the pathogenesis of cataracts linked to this mutant. The efficacy of epoxomicin in restoring function suggests that protease inhibition might have therapeutic value for this and other diseases caused by mutants with similar defects.
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Affiliation(s)
- Peter J Minogue
- Department of Pediatrics, University of Chicago, Chicago, Illinois 60637, USA
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