1
|
Kasture AS, Fischer FP, Kunert L, Burger ML, Burgstaller AC, El-Kasaby A, Hummel T, Sucic S. Drosophila melanogaster as a model for unraveling unique molecular features of epilepsy elicited by human GABA transporter 1 variants. Front Neurosci 2023; 16:1074427. [PMID: 36741049 PMCID: PMC9893286 DOI: 10.3389/fnins.2022.1074427] [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: 10/19/2022] [Accepted: 12/21/2022] [Indexed: 01/20/2023] Open
Abstract
Mutations in the human γ-aminobutyric acid (GABA) transporter 1 (hGAT-1) can instigate myoclonic-atonic and other generalized epilepsies in the afflicted individuals. We systematically examined fifteen hGAT-1 disease variants, all of which dramatically reduced or completely abolished GABA uptake activity. Many of these loss-of-function variants were absent from their regular site of action at the cell surface, due to protein misfolding and/or impaired trafficking machinery (as verified by confocal microscopy and de-glycosylation experiments). A modest fraction of the mutants displayed correct targeting to the plasma membrane, but nonetheless rendered the mutated proteins devoid of GABA transport, possibly due to structural alterations in the GABA binding site/translocation pathway. We here focused on a folding-deficient A288V variant. In flies, A288V reiterated its impeded expression pattern, closely mimicking the ER-retention demonstrated in transfected HEK293 cells. Functionally, A288V presented a temperature-sensitive seizure phenotype in fruit flies. We employed diverse small molecules to restore the expression and activity of folding-deficient hGAT-1 epilepsy variants, in vitro (in HEK293 cells) and in vivo (in flies). We identified three compounds (chemical and pharmacological chaperones) conferring moderate rescue capacity for several variants. Our data grant crucial new insights into: (i) the molecular basis of epilepsy in patients harboring hGAT-1 mutations, and (ii) a proof-of-principle that protein folding deficits in disease-associated hGAT-1 variants can be corrected using the pharmacochaperoning approach. Such innovative pharmaco-therapeutic prospects inspire the rational design of novel drugs for alleviating the clinical symptoms triggered by the numerous emerging pathogenic mutations in hGAT-1.
Collapse
Affiliation(s)
- Ameya S. Kasture
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria,Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Florian P. Fischer
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria,Department of Epileptology and Neurology, University of Aachen, Aachen, Germany
| | - Lisa Kunert
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Melanie L. Burger
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | | | - Ali El-Kasaby
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Thomas Hummel
- Department of Neuroscience and Developmental Biology, University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria,*Correspondence: Sonja Sucic,
| |
Collapse
|
2
|
Trandafir LM, Frăsinariu OE, Țarcă E, Butnariu LI, Leon Constantin MM, Moscalu M, Temneanu OR, Melinte Popescu AS, Popescu MGM, Stârcea IM, Cojocaru E, Moisa SM. Can Bioactive Food Substances Contribute to Cystic Fibrosis-Related Cardiovascular Disease Prevention? Nutrients 2023; 15:314. [PMID: 36678185 PMCID: PMC9860597 DOI: 10.3390/nu15020314] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 12/30/2022] [Accepted: 01/06/2023] [Indexed: 01/11/2023] Open
Abstract
Advances in cystic fibrosis (CF) care have significantly improved the quality of life and life expectancy of patients. Nutritional therapy based on a high-calorie, high-fat diet, antibiotics, as well as new therapies focused on CFTR modulators change the natural course of the disease. They do so by improving pulmonary function and growing BMI. However, the increased weight of such patients can lead to unwanted long-term cardiovascular effects. People with CF (pwCF) experience several cardiovascular risk factors. Such factors include a high-fat diet and increased dietary intake, altered lipid metabolism, a decrease in the level of fat-soluble antioxidants, heightened systemic inflammation, therapeutic interventions, and diabetes mellitus. PwCF must pay special attention to food and eating habits in order to maintain a nutritional status that is as close as possible to the proper physiological one. They also have to benefit from appropriate nutritional counseling, which is essential in the evolution and prognosis of the disease. Growing evidence collected in the last years shows that many bioactive food components, such as phytochemicals, polyunsaturated fatty acids, and antioxidants have favorable effects in the management of CF. An important positive effect is cardiovascular prevention. The possibility of preventing/reducing cardiovascular risk in CF patients enhances both quality of life and life expectancy in the long run.
Collapse
Affiliation(s)
- Laura Mihaela Trandafir
- Department of Mother and Child Medicine–Pediatrics, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iaşi, Romania
| | - Otilia Elena Frăsinariu
- Department of Mother and Child Medicine–Pediatrics, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iaşi, Romania
| | - Elena Țarcă
- Department of Surgery II-Pediatric Surgery, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iaşi, Romania
| | - Lăcrămioara Ionela Butnariu
- Department of Medical Genetics, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iași, Romania
| | | | - Mihaela Moscalu
- Department of Preventive Medicine and Interdisciplinarity, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iași, Romania
| | - Oana Raluca Temneanu
- Department of Mother and Child Medicine–Pediatrics, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iaşi, Romania
| | - Alina Sinziana Melinte Popescu
- Department of General Nursing, Faculty of Medicine and Biological Sciences, “Ştefan cel Mare” University of Suceava, 720229 Suceava, Romania
| | - Marian George Melinte Popescu
- Department of General Nursing, Faculty of Medicine and Biological Sciences, “Ştefan cel Mare” University of Suceava, 720229 Suceava, Romania
| | - Iuliana Magdalena Stârcea
- Department of Mother and Child Medicine–Pediatrics, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iaşi, Romania
| | - Elena Cojocaru
- Department of Morphofunctional Sciences I–Pathology, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iaşi, Romania
| | - Stefana Maria Moisa
- Department of Mother and Child Medicine–Pediatrics, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iaşi, Romania
| |
Collapse
|
3
|
Chindarkar M, Medithi S. Nutraceutical Approach for the Management of Cystic Fibrosis. CURRENT NUTRITION & FOOD SCIENCE 2022. [DOI: 10.2174/1573401318666220415085219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
Cystic fibrosis is an autosomal recessive monogenic disease marked by a mutation in the cystic fibrosis transmembrane conductance regulator gene. Cystic fibrosis transmembrane conductance regulator gene mutations affect respiratory, digestive and reproductive functions and impede bicarbonate, bile acid and sweat secretion. Moreover, the current trend indicates that CF is no longer only a paediatric disease; but has progressively become a disease that also affects adults. This calls to address the condition with an appropriate nutraceutical approach.
Objective:
The study aims to find and collate nutritional targets in the management of Cystic Fibrosis.
Method:
Studies highlighting the benefits of nutrients or nutraceuticals in the management of Cystic Fibrosis were included from previously published research articles (1971 to 2020). Data including nutrients, nutraceuticals, study design, study model, sample size, age, dose and duration of the dose of the supplement were extracted from the studies included and explored to understand their role.
Results:
About 26 studies are being included in the present review. It was found that nutrient interventions comprising nutraceuticals including dietary fibre, proteins and amino acids (taurine, arginine, glutathione), fats (medium-chain triglycerides, polyunsaturated fatty acids (omega-3 fatty acids)), phytochemicals (apigenin, genistein, quercetin, curcumin, allicin, beta-carotene, Pulmonaria officinalis L, Epigallocatechin-3-gallate), micronutrients including vitamin A, vitamin D, vitamin K, magnesium and zinc in addition to antioxidants exhibit improvement in the symptomatic condition of cystic fibrosis patients.
Conclusion:
The advent of nutraceuticals in the food industry and studies indicating their promising benefits have paved a path for targeted therapies in cystic fibrosis.
Collapse
Affiliation(s)
- Manali Chindarkar
- Nutrition and Dietetics, Symbiosis Institute of Health Sciences (SIHS), Symbiosis International (Deemed University), Pune, India
| | - Srujana Medithi
- Nutrition and Dietetics, Symbiosis Institute of Health Sciences (SIHS), Symbiosis International (Deemed University), Pune, India
| |
Collapse
|
4
|
Liu J, Taylor RL, Baines RA, Swanton L, Freeman S, Corneo B, Patel A, Marmorstein A, Knudsen T, Black GC, Manson F. Small Molecules Restore Bestrophin 1 Expression and Function of Both Dominant and Recessive Bestrophinopathies in Patient-Derived Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 2020; 61:28. [PMID: 32421148 PMCID: PMC7405785 DOI: 10.1167/iovs.61.5.28] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Purpose Bestrophinopathies are a group of untreatable inherited retinal dystrophies caused by mutations in the retinal pigment epithelium (RPE) Cl− channel bestrophin 1. We tested whether sodium phenylbutyrate (4PBA) could rescue the function of mutant bestrophin 1 associated with autosomal dominant and recessive disease. We then sought analogues of 4PBA with increased potency and determined the mode of action for 4PBA and a lead compound 2-naphthoxyacetic acid (2-NOAA). Lastly, we tested if 4PBA and 2-NOAA could functionally rescue bestrophin 1 function in RPE generated from induced pluripotent stem cells (iPSC-RPEs) derived from patients with a dominant or recessive bestrophinopathy. Methods Global and plasma membrane expression was determined by Western blot and immunofluorescent microscopy, respectively. The effect of 4PBA and 2-NOAA on transcription was measured by quantitative RT-PCR and the rate of protein turnover by cycloheximide chase and Western blot. Channel function was measured by whole-cell patch clamp. Results 4PBA and 2-NOAA can rescue the global and membrane expression of mutant bestrophin 1 associated with autosomal dominant disease (Best vitelliform macular dystrophy [BVMD]) and autosome recessive bestrophinopathy (ARB), and these small molecules have different modes of action. Both 4PBA and 2-NOAA significantly increased the channel function of mutant BVMD and ARB bestrophin 1 in HEK293T and iPSC-RPE cells derived from patients with BVMD and ARB. For 4PBA, the increased mutant channel function in BVMD and ARB iPSC-RPE was equal to that of wild-type iPSC-RPE bestrophin 1. Conclusions The restoration of bestrophin 1 function in patient-derived RPE confirms the US Food and Drug Administration–approved drug 4PBA as a promising therapeutic treatment for bestrophinopathies.
Collapse
|
5
|
Chen L, Ding Y, Hou Y, Liu Y, Nie H. Regulation of Cl- Electrolyte Permeability in Epithelia by Active Traditional Chinese Medicine Monomers for Diarrhea. Curr Drug Targets 2020; 21:902-909. [PMID: 32364074 DOI: 10.2174/1389450121666200504073635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/25/2020] [Accepted: 02/28/2020] [Indexed: 11/22/2022]
Abstract
The epithelial layer, lining the inner surface of the mammalian alveolar, kidney, brain and colon, is a typical electrolyte transporting tissue. Large quantities of salt and fluid are actively moved from the mucosal side toward the blood vessel. Transepithelial salt re-absorption in epithelial tissues plays an important role in maintaining fluid homeostasis. In absorptive epithelium, fluid and salt flux is controlled by the machinery mainly composed of epithelial sodium channel, cystic fibrosis transmembrane conductance regulator, Na+-K+-2Cl- cotransporter, Na+/H+ exchanger, and Na+/K+-ATPase. Dysregulation of salt permeability across epithelium contributes to the pathogenesis of organ edema. In numerous ion transporters, epithelial Cl- transportation plays an important role in water secretion across epithelial tissues and regulation of body fluid content. Many traditional Chinese medicines treat diarrhea by regulating the Cl- electrolyte transport. We systematically summarized the recent progress regarding the traditional Chinese medicine on Cl- electrolyte transport in the intestinal epithelial tissues. The pharmaceutical relevance of developing advanced strategies to mitigate edematous disorders is also implicated. In conclusion, the crosstalk between Cl- electrolyte transport and active traditional Chinese medicine monomers may lead to the development of new strategies for diarrhea by manipulating the function and expression of ion channels.
Collapse
Affiliation(s)
- Lei Chen
- China Medical University, Shenyang, China
| | - Yan Ding
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Yapeng Hou
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Yanhong Liu
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Hongguang Nie
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| |
Collapse
|
6
|
Prasad R. New Horizons in Correction of Mutated ATP7B in Wilson Disease Using Pharmacological Agents: Precise Medicine. Indian J Clin Biochem 2019; 34:369-370. [PMID: 31686723 DOI: 10.1007/s12291-019-00855-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Rajendra Prasad
- Department of Biochemistry, MM Institute of Medical Sciences and Research, MM (Deemed to be University), Mullana, Ambala, Haryana 133207 India
| |
Collapse
|
7
|
Balestra D, Branchini A. Molecular Mechanisms and Determinants of Innovative Correction Approaches in Coagulation Factor Deficiencies. Int J Mol Sci 2019; 20:ijms20123036. [PMID: 31234407 PMCID: PMC6627357 DOI: 10.3390/ijms20123036] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 06/07/2019] [Accepted: 06/18/2019] [Indexed: 02/07/2023] Open
Abstract
Molecular strategies tailored to promote/correct the expression and/or processing of defective coagulation factors would represent innovative therapeutic approaches beyond standard substitutive therapy. Here, we focus on the molecular mechanisms and determinants underlying innovative approaches acting at DNA, mRNA and protein levels in inherited coagulation factor deficiencies, and in particular on: (i) gene editing approaches, which have permitted intervention at the DNA level through the specific recognition, cleavage, repair/correction or activation of target sequences, even in mutated gene contexts; (ii) the rescue of altered pre-mRNA processing through the engineering of key spliceosome components able to promote correct exon recognition and, in turn, the synthesis and secretion of functional factors, as well as the effects on the splicing of missense changes affecting exonic splicing elements; this section includes antisense oligonucleotide- or siRNA-mediated approaches to down-regulate target genes; (iii) the rescue of protein synthesis/function through the induction of ribosome readthrough targeting nonsense variants or the correction of folding defects caused by amino acid substitutions. Overall, these approaches have shown the ability to rescue the expression and/or function of potentially therapeutic levels of coagulation factors in different disease models, thus supporting further studies in the future aimed at evaluating the clinical translatability of these new strategies.
Collapse
Affiliation(s)
- Dario Balestra
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy.
| | - Alessio Branchini
- Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy.
| |
Collapse
|
8
|
Mai CT, Le QG, Ishiwata-Kimata Y, Takagi H, Kohno K, Kimata Y. 4-Phenylbutyrate suppresses the unfolded protein response without restoring protein folding in Saccharomyces cerevisiae. FEMS Yeast Res 2019; 18:4858386. [PMID: 29452364 DOI: 10.1093/femsyr/foy016] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Accepted: 02/13/2018] [Indexed: 12/16/2022] Open
Abstract
Accumulation of unfolded secretory proteins in the endoplasmic reticulum (ER), namely ER stress, is hazardous to eukaryotic cells and promotes the unfolded protein response (UPR). Ire1 is an ER-located transmembrane protein that senses ER stress and triggers the UPR. According to previous in vitro experiments, 4-phenylbutyrate (4-PBA) works as a chemical molecular chaperone. Since 4-PBA attenuates the UPR in mammalian tissue cultures, this chemical may have clinical potential for restoring ER-stressing conditions. In this study, we investigated 4-PBA's mode of action using the yeast Saccharomyces cerevisiae as a model organism. Although 4-PBA blocked a dithiothreitol (DTT)-induced UPR, it did not appear to restore impairment of ER protein folding that was caused by DTT. Moreover, even under non-stress conditions, 4-PBA attenuated UPR that was induced by an Ire1 mutant that exhibits a substantial activity without sensing ER accumulation of unfolded proteins. We also found that 4-PBA drastically promotes the degradation of Ire1. These observations indicate that at least in the case of yeast cells, 4-PBA suppresses the UPR not through restoration of the ER function to correctly fold proteins. Instead, the accelerated degradation of Ire1 possibly explains the reason why the UPR is attenuated by 4-PBA.
Collapse
Affiliation(s)
- Chi Thanh Mai
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Quynh Giang Le
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Yuki Ishiwata-Kimata
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Hiroshi Takagi
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Kenji Kohno
- Institute for Research Initiatives, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Yukio Kimata
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| |
Collapse
|
9
|
Tosco A, Villella VR, Castaldo A, Kroemer G, Maiuri L, Raia V. Repurposing therapies for the personalised treatment of cystic fibrosis. Expert Opin Orphan Drugs 2018. [DOI: 10.1080/21678707.2018.1483231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Antonella Tosco
- Regional Cystic Fibrosis Center, Pediatric Unit, Department of Translational Medical Sciences, Federico II University, Naples, Italy
| | - Valeria R. Villella
- European Institute for Research in Cystic Fibrosis, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Alice Castaldo
- Regional Cystic Fibrosis Center, Pediatric Unit, Department of Translational Medical Sciences, Federico II University, Naples, Italy
| | - Guido Kroemer
- Equipe11 labellisée Ligue Nationale Contrele Cancer, Centre de Recherche des Cordeliers, Paris, France
- INSERM U1138, Centre de Recherche des Cordeliers, Paris, France
- Université Paris Descartes, Paris, Sorbonne Paris Cité, France
- Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France
- Pôle de Biologie, HôpitalEuropéen Georges Pompidou, AP-HP, Paris, France
| | - Luigi Maiuri
- European Institute for Research in Cystic Fibrosis, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
- Department of Health Sciences, University of Eastern Piedmont, Novara, Italy
| | - Valeria Raia
- Regional Cystic Fibrosis Center, Pediatric Unit, Department of Translational Medical Sciences, Federico II University, Naples, Italy
| |
Collapse
|
10
|
Uggenti C, Briant K, Streit AK, Thomson S, Koay YH, Baines RA, Swanton E, Manson FD. Restoration of mutant bestrophin-1 expression, localisation and function in a polarised epithelial cell model. Dis Model Mech 2016; 9:1317-1328. [PMID: 27519691 PMCID: PMC5117222 DOI: 10.1242/dmm.024216] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 07/21/2016] [Indexed: 01/13/2023] Open
Abstract
Autosomal recessive bestrophinopathy (ARB) is a retinopathy caused by mutations in the bestrophin-1 protein, which is thought to function as a Ca2+-gated Cl− channel in the basolateral surface of the retinal pigment epithelium (RPE). Using a stably transfected polarised epithelial cell model, we show that four ARB mutant bestrophin-1 proteins were mislocalised and subjected to proteasomal degradation. In contrast to the wild-type bestrophin-1, each of the four mutant proteins also failed to conduct Cl− ions in transiently transfected cells as determined by whole-cell patch clamp. We demonstrate that a combination of two clinically approved drugs, bortezomib and 4-phenylbutyrate (4PBA), successfully restored the expression and localisation of all four ARB mutant bestrophin-1 proteins. Importantly, the Cl− conductance function of each of the mutant bestrophin-1 proteins was fully restored to that of wild-type bestrophin-1 by treatment of cells with 4PBA alone. The functional rescue achieved with 4PBA is significant because it suggests that this drug, which is already approved for long-term use in infants and adults, might represent a promising therapy for the treatment of ARB and other bestrophinopathies resulting from missense mutations in BEST1. Summary: Chemical chaperone 4PBA fully restores Cl− conductance activity for mutant bestrophin-1 proteins associated with inherited retinal dystrophy, autosomal recessive bestrophinopathy.
Collapse
Affiliation(s)
- Carolina Uggenti
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Kit Briant
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Anne-Kathrin Streit
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Steven Thomson
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Yee Hui Koay
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Richard A Baines
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Eileithyia Swanton
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Forbes D Manson
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| |
Collapse
|
11
|
The therapeutic effects of 4-phenylbutyric acid in maintaining proteostasis. Int J Biochem Cell Biol 2015; 61:45-52. [PMID: 25660369 DOI: 10.1016/j.biocel.2015.01.015] [Citation(s) in RCA: 190] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 12/11/2022]
Abstract
Recently, there has been an increasing amount of literature published on the effects of 4-phenylbutyric acid (4-PBA) in various biological systems. 4-PBA is currently used clinically to treat urea cycle disorders under the trade name Buphenyl. Recent studies however have explored 4-PBA in the context of a low weight molecular weight chemical chaperone. Its properties as a chemical chaperone prevent misfolded protein aggregation and alleviate endoplasmic reticulum (ER) stress. As the ER is responsible for folding proteins targeted for use in membranes or secreted out of the cell, failure of maintaining adequate ER homeostasis may lead to protein misfolding and subsequent cell and organ pathology. Accumulation of misfolded proteins within the ER activates the unfolded protein response (UPR), a molecular repair response. The activation of the UPR aims to restore ER and cellular proteostasis by regulating the rate of synthesis of newly formed proteins as well as initiating molecular programs aimed to help fold or degrade misfolded proteins. If proteostasis is not restored, the UPR may initiate pro-apoptotic pathways. It is suggested that 4-PBA may help fold proteins in the ER, attenuating the activation of the UPR, and thus potentially alleviating various pathologies. This review discusses the biomedical research exploring the potential therapeutic effects of 4-PBA in various in vitro and in vivo model systems and clinical trials, while also commenting on the possible mechanisms of action.
Collapse
|
12
|
Ramachandran S, Osterhaus SR, Karp PH, Welsh MJ, McCray PB. A genomic signature approach to rescue ΔF508-cystic fibrosis transmembrane conductance regulator biosynthesis and function. Am J Respir Cell Mol Biol 2014; 51:354-62. [PMID: 24669817 DOI: 10.1165/rcmb.2014-0007oc] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The most common cystic fibrosis (CF) mutation, ΔF508, causes protein misfolding, leading to proteosomal degradation. We recently showed that expression of miR-138 enhances CF transmembrane conductance regulator (CFTR) biogenesis and partially rescues ΔF508-CFTR function in CF airway epithelia. We hypothesized that a genomic signature approach can be used to identify new bioactive small molecules affecting ΔF508-CFTR rescue. The Connectivity Map was used to identify 27 small molecules with potential to restore ΔF508-CFTR function in airway epithelia. The molecules were screened in vitro for efficacy in improving ΔF508-CFTR trafficking, maturation, and chloride current. We identified four small molecules that partially restore ΔF508-CFTR function in primary CF airway epithelia. Of these, pyridostigmine showed cooperativity with corrector compound 18 in improving ΔF508-CFTR function. There are few CF therapies based on new molecular insights. Querying the Connectivity Map with relevant genomic signatures offers a method to identify new candidates for rescuing ΔF508-CFTR function.
Collapse
|
13
|
West J, Austin E, Fessel JP, Loyd J, Hamid R. Rescuing the BMPR2 signaling axis in pulmonary arterial hypertension. Drug Discov Today 2014; 19:1241-5. [PMID: 24794464 DOI: 10.1016/j.drudis.2014.04.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 04/24/2014] [Indexed: 01/10/2023]
Abstract
Pulmonary arterial hypertension (PAH) is a lethal disorder characterized by pulmonary arterial remodeling, increased right ventricular systolic pressure (RVSP), vasoconstriction and inflammation. The heritable form of PAH (HPAH) is usually (>80%) caused by mutations in the bone morphogenic protein receptor 2 (BMPR2) gene. Existing treatments for PAH typically focus on the end-stage sequelae of the disease, but do not address underlying mechanisms of vascular obstruction and blood flow and thus, in the long run, have limited effect because they treat the symptoms rather than the cause. Over the past decade, improved understanding of the molecular mechanisms behind the disease has enabled us to consider several novel therapeutic pathways. These include approaches directed toward BMPR2 gene expression, alternative splicing, downstream BMP signaling, metabolic pathways and the role of estrogens and estrogenic compounds in BMP signaling. It is likely that, ultimately, only one or two of these pathways will generate meaningful treatment options, however the potential benefits to PAH patients are still likely to be significant.
Collapse
Affiliation(s)
- James West
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
| | - Eric Austin
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Joshua P Fessel
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - James Loyd
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Rizwan Hamid
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
| |
Collapse
|
14
|
Kemter E, Sklenak S, Rathkolb B, Hrabě de Angelis M, Wolf E, Aigner B, Wanke R. No amelioration of uromodulin maturation and trafficking defect by sodium 4-phenylbutyrate in vivo: studies in mouse models of uromodulin-associated kidney disease. J Biol Chem 2014; 289:10715-10726. [PMID: 24567330 DOI: 10.1074/jbc.m113.537035] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Uromodulin (UMOD)-associated kidney disease (UAKD) belongs to the hereditary progressive ER storage diseases caused by maturation defects of mutant UMOD protein. Current treatments of UAKD patients are symptomatic and cannot prevent disease progression. Two in vitro studies reported a positive effect of the chemical chaperone sodium 4-phenylbutyrate (4-PBA) on mutant UMOD maturation. Thus, 4-PBA was suggested as a potential treatment for UAKD. This study evaluated the effects of 4-PBA in two mouse models of UAKD. In contrast to previous in vitro studies, treatment with 4-PBA did not increase HSP70 expression or improve maturation and trafficking of mutant UMOD in vivo. Kidney function of UAKD mice was actually deteriorated by 4-PBA treatment. In transfected tubular epithelial cells, 4-PBA did not improve maturation but increased the expression level of both mutant and wild-type UMOD protein. Activation of NF-κB pathway in thick ascending limb of Henle's loop cells of UAKD mice was detected by increased abundance of RelB and phospho-IκB kinase α/β, an indirect activator of NF-κB. Furthermore, the abundance of NF-κB1 p105/p50, NF-κB2 p100/p52, and TRAF2 was increased in UAKD. NF-κB activation was identified as a novel disease mechanism of UAKD and might be a target for therapeutic intervention.
Collapse
Affiliation(s)
- Elisabeth Kemter
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, 81377 Munich, Germany.
| | - Stefanie Sklenak
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Birgit Rathkolb
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, 81377 Munich, Germany; German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, 85764 Neuherberg, Germany; German Research Center of Diabetes Research (DZD), Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Martin Hrabě de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, 85764 Neuherberg, Germany; German Research Center of Diabetes Research (DZD), Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Eckhard Wolf
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Bernhard Aigner
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Ruediger Wanke
- Institute of Veterinary Pathology, Center for Clinical Veterinary Medicine, Ludwig-Maximilians-Universität München, 80539 Munich, Germany
| |
Collapse
|
15
|
Iram SH, Cole SPC. Differential functional rescue of Lys(513) and Lys(516) processing mutants of MRP1 (ABCC1) by chemical chaperones reveals different domain-domain interactions of the transporter. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:756-65. [PMID: 24231430 DOI: 10.1016/j.bbamem.2013.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/24/2013] [Accepted: 11/04/2013] [Indexed: 12/15/2022]
Abstract
Multidrug resistance protein 1 (MRP1) extrudes drugs as well as pharmacologically and physiologically important organic anions across the plasma membrane in an ATP-dependent manner. We previously showed that Ala substitutions of Lys(513) and Lys(516) in the cytoplasmic loop (CL5) connecting transmembrane helix 9 (TM9) to TM10 cause misfolding of MRP1, abrogating its expression at the plasma membrane in transfected human embryonic kidney (HEK) cells. Exposure of HEK cells to the chemical chaperones glycerol, DMSO, polyethylene glycol (PEG) and 4-aminobutyric acid (4-PBA) improved levels of K513A to wild-type MRP1 levels but transport activity was only fully restored by 4-PBA or DMSO treatments. Tryptic fragmentation patterns and conformation-dependent antibody immunoreactivity of the transport-deficient PEG- and glycerol-rescued K513A proteins indicated that the second nucleotide binding domain (NBD2) had adopted a more open conformation than in wild-type MRP1. This structural change was accompanied by differences in ATP binding and hydrolysis but no changes in substrate Km. In contrast to K513A, K516A levels in HEK cells were not significantly enhanced by chemical chaperones. In more permissive insect cells, however, K516A levels were comparable to wild-type MRP1. Nevertheless, organic anion transport by K516A in insect cell membranes was reduced by >80% due to reduced substrate Km. Tryptic fragmentation patterns indicated a more open conformation of the third membrane spanning domain of MRP1. Thus, despite their close proximity to one another in CL5, Lys(513) and Lys(516) participate in different interdomain interactions crucial for the proper folding and assembly of MRP1.
Collapse
Affiliation(s)
- Surtaj H Iram
- Division of Cancer Biology and Genetics, Queen's University, Kingston, ON K7L 3N6, Canada; Department of Pathology & Molecular Medicine, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Susan P C Cole
- Division of Cancer Biology and Genetics, Queen's University, Kingston, ON K7L 3N6, Canada; Department of Pathology & Molecular Medicine, Queen's University, Kingston, ON K7L 3N6, Canada.
| |
Collapse
|
16
|
Frump AL, Lowery JW, Hamid R, Austin ED, de Caestecker M. Abnormal trafficking of endogenously expressed BMPR2 mutant allelic products in patients with heritable pulmonary arterial hypertension. PLoS One 2013; 8:e80319. [PMID: 24224048 PMCID: PMC3818254 DOI: 10.1371/journal.pone.0080319] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 10/07/2013] [Indexed: 12/28/2022] Open
Abstract
More than 200 heterozygous mutations in the type 2 BMP receptor gene, BMPR2, have been identified in patients with Heritable Pulmonary Arterial Hypertension (HPAH). More severe clinical outcomes occur in patients with BMPR2 mutations by-passing nonsense-mediated mRNA decay (NMD negative mutations). These comprise 40% of HPAH mutations and are predicted to express BMPR2 mutant products. However expression of endogenous NMD negative BMPR2 mutant products and their effect on protein trafficking and signaling function have never been described. Here, we characterize the expression and trafficking of an HPAH-associated NMD negative BMPR2 mutation that results in an in-frame deletion of BMPR2 EXON2 (BMPR2ΔEx2) in HPAH patient-derived lymphocytes and in pulmonary endothelial cells (PECs) from mice carrying the same in-frame deletion of Exon 2 (Bmpr2 (ΔEx2/+) mice). The endogenous BMPR2ΔEx2 mutant product does not reach the cell surface and is retained in the endoplasmic reticulum. Moreover, chemical chaperones 4-PBA and TUDCA partially restore cell surface expression of Bmpr2ΔEx2 in PECs, suggesting that the mutant product is mis-folded. We also show that PECs from Bmpr2 (ΔEx2/+) mice have defects in the BMP-induced Smad1/5/8 and Id1 signaling axis, and that addition of chemical chaperones restores expression of the Smad1/5/8 target Id1. These data indicate that the endogenous NMD negative BMPRΔEx2 mutant product is expressed but has a folding defect resulting in ER retention. Partial correction of this folding defect and restoration of defective BMP signaling using chemical chaperones suggests that protein-folding agents could be used therapeutically in patients with these NMD negative BMPR2 mutations.
Collapse
Affiliation(s)
- Andrea L. Frump
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jonathan W. Lowery
- Department of Developmental Biology, Harvard University School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Rizwan Hamid
- Department of Pediatrics, Division of Molecular Genetics and Genomic Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Eric D. Austin
- Department of Pediatrics, Division of Pediatric Pulmonary Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Mark de Caestecker
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- *E-mail:
| |
Collapse
|
17
|
Modulation of the expression of the proinflammatory IL-8 gene in cystic fibrosis cells by extracts deriving from olive mill waste water. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:960603. [PMID: 23935691 PMCID: PMC3723063 DOI: 10.1155/2013/960603] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 04/22/2013] [Accepted: 04/29/2013] [Indexed: 11/25/2022]
Abstract
A persistent recruitment of neutrophils in the bronchi of cystic fibrosis (CF) patients contributes to aggravate the airway tissue damage, suggesting the importance of modulating the expression of chemokines, including IL-8 during the management of the CF patients. Polyphenols rich extracts derived from waste water from olive mill, obtained by a molecular imprinting approach, have been investigated in order to discover compounds able to reduce IL-8 expression in human bronchial epithelial cells (IB3-1 cells), derived from a CF patient with a ΔF508/W1282X mutant genotype and stimulated with TNF-alpha. Initially, electrophoretic mobility shift assays (EMSAs) were performed to determine whether the different active principles were able to inhibit the binding between transcription factor (TF) NF-kappaB and DNA consensus sequences. Among different representative active principles present in the extract, three compounds were selected, apigenin, oleuropein, and cyanidin chloride, which displayed remarkable activity in inhibiting NF-kappaB/DNA complexes. Utilizing TNF-alpha-treated IB3-1 cells as experimental model system, we demonstrated that apigenin and cyanidin chloride are able to modulate the expression of the NF-kappaB-regulated IL-8 gene, while oleuropein showed no effect in regulating the expression of the gene IL-8.
Collapse
|
18
|
Sarankó H, Tordai H, Telbisz Á, Özvegy-Laczka C, Erdős G, Sarkadi B, Hegedűs T. Effects of the gout-causing Q141K polymorphism and a CFTR ΔF508 mimicking mutation on the processing and stability of the ABCG2 protein. Biochem Biophys Res Commun 2013; 437:140-5. [PMID: 23800412 DOI: 10.1016/j.bbrc.2013.06.054] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 06/14/2013] [Indexed: 12/19/2022]
Abstract
ABCG2 is an important multidrug transporter involved also in urate transport, thus its mutations can lead to the development of gout and may also alter general drug absorption, distribution and excretion. The frequent ABCG2 polymorphism, Q141K, is associated with an elevated risk of gout and has been controversially reported to reduce the plasma membrane expression and/or the transport function of the protein. In the present work we examined the stability and cellular processing of the Q141K ABCG2 variant, as well as that of the ΔF142 ABCG2, corresponding to the ΔF508 mutation in the CFTR (ABCC7) protein, causing cystic fibrosis. The processing and localization of full length ABCG2 variants were investigated in mammalian cells, followed by Western blotting and confocal microscopy, respectively. Folding and stability were examined by limited proteolysis of Sf9 insect cell membranes expressing these ABCG2 constructs. Stability of isolated nucleotide binding domains, expressed in and purified from bacteria, was studied by CD spectroscopy. We find that the Q141K variant has a mild processing defect which can be rescued by low temperature, a slightly reduced activity, and a mild folding defect, especially affecting the NBD. In contrast, the ΔF142 mutant has major processing and folding defects, and no ATPase function. We suggest that although these mutations are both localized within the NBD, based on molecular modeling their contribution to the ABCG2 structure and function is different, thus rescue strategies may be devised accordingly.
Collapse
|
19
|
Besio R, Gioia R, Cossu F, Monzani E, Nicolis S, Cucca L, Profumo A, Casella L, Tenni R, Bolognesi M, Rossi A, Forlino A. Kinetic and structural evidences on human prolidase pathological mutants suggest strategies for enzyme functional rescue. PLoS One 2013; 8:e58792. [PMID: 23516557 PMCID: PMC3596340 DOI: 10.1371/journal.pone.0058792] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 02/06/2013] [Indexed: 12/17/2022] Open
Abstract
Prolidase is the only human enzyme responsible for the digestion of iminodipeptides containing proline or hydroxyproline at their C-terminal end, being a key player in extracellular matrix remodeling. Prolidase deficiency (PD) is an intractable loss of function disease, characterized by mutations in the prolidase gene. The exact causes of activity impairment in mutant prolidase are still unknown. We generated three recombinant prolidase forms, hRecProl-231delY, hRecProl-E412K and hRecProl-G448R, reproducing three mutations identified in homozygous PD patients. The enzymes showed very low catalytic efficiency, thermal instability and changes in protein conformation. No variation of Mn(II) cofactor affinity was detected for hRecProl-E412K; a compromised ability to bind the cofactor was found in hRecProl-231delY and Mn(II) was totally absent in hRecProl-G448R. Furthermore, local structure perturbations for all three mutants were predicted by in silico analysis. Our biochemical investigation of the three causative alleles identified in perturbed folding/instability, and in consequent partial prolidase degradation, the main reasons for enzyme inactivity. Based on the above considerations we were able to rescue part of the prolidase activity in patients’ fibroblasts through the induction of Heath Shock Proteins expression, hinting at new promising avenues for PD treatment.
Collapse
Affiliation(s)
- Roberta Besio
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Roberta Gioia
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Federica Cossu
- Department of BioSciences, CNR-IBF and CIMAINA, University of Milano, Milano, Italy
| | - Enrico Monzani
- Department of Chemistry, University of Pavia, Pavia, Italy
| | | | - Lucia Cucca
- Department of Chemistry, University of Pavia, Pavia, Italy
| | | | - Luigi Casella
- Department of Chemistry, University of Pavia, Pavia, Italy
| | - Ruggero Tenni
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Martino Bolognesi
- Department of BioSciences, CNR-IBF and CIMAINA, University of Milano, Milano, Italy
| | - Antonio Rossi
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
| | - Antonella Forlino
- Department of Molecular Medicine, Biochemistry Unit, University of Pavia, Pavia, Italy
- * E-mail:
| |
Collapse
|
20
|
Pawlikowska-Pawlęga B, Misiak LE, Zarzyka B, Paduch R, Gawron A, Gruszecki WI. FTIR, (1)H NMR and EPR spectroscopy studies on the interaction of flavone apigenin with dipalmitoylphosphatidylcholine liposomes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:518-27. [PMID: 23088916 DOI: 10.1016/j.bbamem.2012.10.013] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 09/27/2012] [Accepted: 10/15/2012] [Indexed: 11/25/2022]
Abstract
Apigenin (5,7,4'-trihydroxyflavone) is a cancer chemopreventive agent and a member of the family of plant flavonoids. Apigenin interaction with liposomes formed with dipalmitoylphosphatidylcholine (DPPC) was investigated by means of FTIR spectroscopy, (1)H NMR and EPR techniques. Fluorescent microscopy and electron microscopy were applied to study the apigenin effects on colon myofibroblasts and human skin fibroblasts. The strong rigidifying effect of apigenin with respect to polar head groups was concluded on the basis of the action of the flavone on partition coefficient of Tempo spin label between the water and lipid phases. The ordering effect was also found in hydrophobic region at the depth monitored by 5-SASL and 16-SASL spin labels. The inclusion of apigenin to the membrane restricted the motional freedom of polar head groups lowering penetration of Pr(3+) ions to the membranes. The (1)H NMR technique supported also the restriction of motional freedom of the membrane in the hydrophobic region, especially in the zone of CH(2) groups of alkyl chains. FTIR analysis showed that apigenin incorporates into DPPC liposomes via hydrogen bonding between its own hydroxyl groups and lipid polar head groups in the C-O-P-O-C segment. It is also very likely that hydroxyl groups of apigenin link with polar groups of DPPC by water bridges. Electron and fluorescence microscopic observations revealed changes in the internal membrane organization of the examined cells. In conclusion, the changes of the structural and dynamic properties of membranes can be crucial for processes involving tumor suppression signal transduction pathways and cell cycle regulation.
Collapse
Affiliation(s)
- Bożena Pawlikowska-Pawlęga
- Department of Comparative Anatomy and Anthropology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
| | | | | | | | | | | |
Collapse
|
21
|
Abstract
Histone acetyltransferase and histone deacetylase are enzymes responsible for histone acetylation and deacetylation, respectively, in which the histones are acetylated and deacetylated on lysine residues in the N-terminal tail and on the surface of the nucleosome core. These processes are considered the most important epigenetic mechanisms for remodeling the chromatin structure and controlling the gene expression. Histone acetylation is associated with gene activation. Sodium phenylbutyrate is a histone deacetylase inhibitor that has been approved for treatement of urea cycle disorders and is under investigation in cancer, hemoglobinopathies, motor neuron diseases, and cystic fibrosis clinical trials. Due to its characteristics, not only of histone deacetylase inhibitor, but also of ammonia sink and chemical chaperone, the interest towards this molecule is growing worldwide. This review aims to update the current literature, involving the use of sodium phenylbutyrate in experimental studies and clinical trials.
Collapse
Affiliation(s)
- Tommaso Iannitti
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, UK.
| | | |
Collapse
|
22
|
Endoplasmic reticulum stress and lipid metabolism: mechanisms and therapeutic potential. Biochem Res Int 2011; 2012:841362. [PMID: 22195283 PMCID: PMC3238353 DOI: 10.1155/2012/841362] [Citation(s) in RCA: 153] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Accepted: 10/18/2011] [Indexed: 12/11/2022] Open
Abstract
The endoplasmic reticulum (ER) plays a crucial role in protein folding, assembly, and secretion. Disruption of ER homeostasis may lead to accumulation of misfolded or unfolded proteins in the ER lumen, a condition referred to as ER stress. In response to ER stress, a signal transduction pathway known as the unfolded protein response (UPR) is activated. UPR activation allows the cell to cope with an increased protein-folding demand on the ER. Recent studies have shown that ER stress/UPR activation plays a critical role in lipid metabolism and homeostasis. ER-stress-dependent dysregulation of lipid metabolism may lead to dyslipidemia, insulin resistance, cardiovascular disease, type 2 diabetes, and obesity. In this paper, we examine recent findings illustrating the important role ER stress/UPR signalling pathways play in regulation of lipid metabolism, and how they may lead to dysregulation of lipid homeostasis.
Collapse
|
23
|
Rogan MP, Stoltz DA, Hornick DB. Cystic fibrosis transmembrane conductance regulator intracellular processing, trafficking, and opportunities for mutation-specific treatment. Chest 2011; 139:1480-1490. [PMID: 21652558 DOI: 10.1378/chest.10-2077] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Recent advances in basic science have greatly expanded our understanding of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR), the chloride and bicarbonate channel that is encoded by the gene, which is mutated in patients with CF. We review the structure, function, biosynthetic processing, and intracellular trafficking of CFTR and discuss the five classes of mutations and their impact on the CF phenotype. The therapeutic discussion is focused on the significant progress toward CFTR mutation-specific therapies. We review the results of encouraging clinical trials examining orally administered therapeutics, including agents that promote read-through of class I mutations (premature termination codons); correctors, which overcome the CFTR misfolding that characterizes the common class II mutation F508del; and potentiators, which enhance the function of class III or IV mutated CFTR at the plasma membrane. Long-term outcomes from successful mutation-specific treatments could finally answer the question that has been lingering since and even before the CFTR gene discovery: Will therapies that specifically restore CFTR-mediated chloride secretion slow or arrest the deleterious cascade of events leading to chronic infection, bronchiectasis, and end-stage lung disease?
Collapse
Affiliation(s)
- Mark P Rogan
- Department of Respiratory Medicine, Waterford Regional Hospital, Waterford, Ireland
| | - David A Stoltz
- Department of Internal Medicine, Division of Pulmonary, Critical Care, and Occupational Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA
| | - Douglas B Hornick
- Department of Internal Medicine, Division of Pulmonary, Critical Care, and Occupational Medicine, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA.
| |
Collapse
|
24
|
Braiterman L, Nyasae L, Leves F, Hubbard AL. Critical roles for the COOH terminus of the Cu-ATPase ATP7B in protein stability, trans-Golgi network retention, copper sensing, and retrograde trafficking. Am J Physiol Gastrointest Liver Physiol 2011; 301:G69-81. [PMID: 21454443 PMCID: PMC3129927 DOI: 10.1152/ajpgi.00038.2011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
ATP7A and ATP7B are copper-transporting P-type ATPases that are essential to eukaryotic copper homeostasis and must traffic between intracellular compartments to carry out their functions. Previously, we identified a nine-amino acid sequence (F37-E45) in the NH(2) terminus of ATP7B that is required to retain the protein in the Golgi when copper levels are low and target it apically in polarized hepatic cells when copper levels rise. To understand further the mechanisms regulating the intracellular dynamics of ATP7B, using multiple functional assays, we characterized the protein phenotypes of 10 engineered and Wilson disease-associated mutations in the ATP7B COOH terminus in polarized hepatic cells and fibroblasts. We also examined the behavior of a chimera between ATP7B and ATP7A. Our results clearly demonstrate the importance of the COOH terminus of ATP7B in the protein's copper-responsive apical trafficking. L1373 at the end of transmembrane domain 8 is required for protein stability and Golgi retention in low copper, the trileucine motif (L1454-L1456) is required for retrograde trafficking, and the COOH terminus of ATP7B exhibits a higher sensitivity to copper than does ATP7A. Importantly, our results demonstrating that four Wilson disease-associated missense mutations behaved in a wild-type manner in all our assays, together with current information in the literature, raise the possibility that several may not be disease-causing mutations.
Collapse
Affiliation(s)
- L. Braiterman
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - L. Nyasae
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - F. Leves
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - A. L. Hubbard
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| |
Collapse
|
25
|
Targeting Huntington's disease through histone deacetylases. Clin Epigenetics 2011; 2:257-77. [PMID: 22704341 PMCID: PMC3365382 DOI: 10.1007/s13148-011-0025-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 02/06/2011] [Indexed: 12/23/2022] Open
Abstract
Huntington’s disease (HD) is a debilitating neurodegenerative condition with significant burdens on both patient and healthcare costs. Despite extensive research, treatment options for patients with this condition remain limited. Aberrant post-translational modification (PTM) of proteins is emerging as an important element in the pathogenesis of HD. These PTMs include acetylation, phosphorylation, methylation, sumoylation and ubiquitination. Several families of proteins are involved with the regulation of these PTMs. In this review, I discuss the current evidence linking aberrant PTMs and/or aberrant regulation of the cellular machinery regulating these PTMs to HD pathogenesis. Finally, I discuss the evidence suggesting that pharmacologically targeting one of these protein families the histone deacetylases may be of potential therapeutic benefit in the treatment of HD.
Collapse
|
26
|
Collawn JF, Fu L, Bebok Z. Targets for cystic fibrosis therapy: proteomic analysis and correction of mutant cystic fibrosis transmembrane conductance regulator. Expert Rev Proteomics 2010; 7:495-506. [PMID: 20653506 DOI: 10.1586/epr.10.45] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Proteomic analysis has proved to be an important tool for understanding the complex nature of genetic disorders, such as cystic fibrosis (CF), by defining the cellular protein environment (proteome) associated with wild-type and mutant proteins. Proteomic screens identified the proteome of CF transmembrane conductance regulator (CFTR), and provided fundamental information to studies designed for understanding the crucial components of physiological CFTR function. Simultaneously, high-throughput screens for small-molecular correctors of CFTR mutants provided promising candidates for therapy. The majority of CF cases are caused by nucleotide deletions (DeltaF508 CFTR; >75%), resulting in CFTR misfolding, or insertion of premature termination codons ( approximately 10%), leading to unstable mRNA and reduced levels of truncated dysfunctional CFTR. In this article, we review recent results of proteomic screens, developments in identifying correctors for the most frequent CFTR mutants, and comment on how integration of the knowledge gained from these studies may aid in finding a cure for CF and a number of other genetic disorders.
Collapse
Affiliation(s)
- James F Collawn
- University of Alabama at Birmingham, Department of Cell Biology, Birmingham, AL, USA.
| | | | | |
Collapse
|
27
|
Pyle LC, Fulton JC, Sloane PA, Backer K, Mazur M, Prasain J, Barnes S, Clancy JP, Rowe SM. Activation of the cystic fibrosis transmembrane conductance regulator by the flavonoid quercetin: potential use as a biomarker of ΔF508 cystic fibrosis transmembrane conductance regulator rescue. Am J Respir Cell Mol Biol 2010; 43:607-616. [PMID: 20042712 PMCID: PMC2970857 DOI: 10.1165/rcmb.2009-0281oc] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Accepted: 10/24/2009] [Indexed: 12/10/2023] Open
Abstract
Therapies to correct the ΔF508 cystic fibrosis transmembrane conductance regulator (CFTR) folding defect require sensitive methods to detect channel activity in vivo. The β₂ adrenergic receptor agonists, which provide the CFTR stimuli commonly used in nasal potential difference assays, may not overcome the channel gating defects seen in ΔF508 CFTR after plasma membrane localization. In this study, we identify an agent, quercetin, that enhances the detection of surface ΔF508 CFTR, and is suitable for nasal perfusion. A screen of flavonoids in CFBE41o⁻ cells stably transduced with ΔF508 CFTR, corrected to the cell surface with low temperature growth, revealed that quercetin stimulated an increase in the short-circuit current. This increase was dose-dependent in both Fisher rat thyroid and CFBE41o⁻ cells. High concentrations inhibited Cl⁻ conductance. In CFBE41o⁻ airway cells, quercetin (20 μg/ml) activated ΔF508 CFTR, whereas the β₂ adrenergic receptor agonist isoproterenol did not. Quercetin had limited effects on cAMP levels, but did not produce detectable phosphorylation of the isolated CFTR R-domain, suggesting an activation independent of channel phosphorylation. When perfused in the nares of Cftr(+) mice, quercetin (20 μg/ml) produced a hyperpolarization of the potential difference that was absent in Cftr(-/-) mice. Finally, quercetin-induced, dose-dependent hyperpolarization of the nasal potential difference was also seen in normal human subjects. Quercetin activates CFTR-mediated anion transport in respiratory epithelia in vitro and in vivo, and may be useful in studies intended to detect the rescue of ΔF508 CFTR by nasal potential difference.
Collapse
Affiliation(s)
- Louise C. Pyle
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jennifer C. Fulton
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Peter A. Sloane
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Kyle Backer
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Marina Mazur
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jeevan Prasain
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Stephen Barnes
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - J. P. Clancy
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Steven M. Rowe
- Departments of Medicine, Pediatrics, Pharmacology, Genetics, and Physiology, and Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama
| |
Collapse
|
28
|
Engin F, Hotamisligil GS. Restoring endoplasmic reticulum function by chemical chaperones: an emerging therapeutic approach for metabolic diseases. Diabetes Obes Metab 2010; 12 Suppl 2:108-15. [PMID: 21029307 DOI: 10.1111/j.1463-1326.2010.01282.x] [Citation(s) in RCA: 189] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The endoplasmic reticulum (ER) is a eukaryotic organelle that plays important roles in protein synthesis, folding and trafficking, calcium homoeostasis and lipid and steroid synthesis. It is the major protein synthesis compartment for secreted, plasma membrane and organelle proteins. Perturbations of ER homeostasis such as the accumulation of unfolded or misfolded proteins cause ER stress. To alleviate this stress, ER triggers an evolutionarily conserved signalling cascade called the unfolded protein response (UPR). As an initial response, the UPR aims at adapting and restoring ER function by translational attenuation, upregulation of ER chaperones and degradation of unfolded proteins. However, if the ER function is severely impaired because of excessive or prolonged exposure to stress, then the inflicted cells may undergo programmed cell death. During ER stress, unstable or partially folded mutant proteins are prevented from trafficking to their proper subcellular localizations and usually rapidly degraded. The small molecules named chemical chaperones help to stabilize these mutant proteins and facilitate their folding and proper trafficking from the ER to their final destinations. Because increasing number of studies suggest that ER stress is involved in a number of disease pathogenesis including neurodegenerative diseases, cancer, obesity, diabetes and atherosclerosis, promoting ER folding capacity through chemical chaperones emerges as a novel therapeutic approach. In this review, we provide insight into the many important functions of chemical chaperones during ER stress, their impact on the ER-stress-related pathologies and their potential as a new drug targets, especially in the context of metabolic disorders.
Collapse
Affiliation(s)
- F Engin
- Department of Genetics & Complex Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | | |
Collapse
|
29
|
Basseri S, Lhoták S, Sharma AM, Austin RC. The chemical chaperone 4-phenylbutyrate inhibits adipogenesis by modulating the unfolded protein response. J Lipid Res 2010; 50:2486-501. [PMID: 19461119 DOI: 10.1194/jlr.m900216-jlr200] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Recent studies have shown a link between obesity and endoplasmic reticulum (ER) stress. Perturbations in ER homeostasis cause ER stress and activation of the unfolded protein response (UPR). Adipocyte differentiation contributes to weight gain, and we have shown that markers of ER stress/UPR activation, including GRP78, phospho-eIF2, and spliced XBP1, are upregulated during adipogenesis. Given these findings, the objective of this study was to determine whether attenuation of UPR activation by the chemical chaperone 4-phenylbutyrate (4-PBA) inhibits adipogenesis. Exposure of 3T3-L1 preadipocytes to 4-PBA in the presence of differentiation media decreased expression of ER stress markers. Concomitant with the suppression of UPR activation, 4-PBA resulted in attenuation of adipogenesis as measured by lipid accumulation and adiponectin secretion. Consistent with these in vitro findings, female C57BL/6 mice fed a high-fat diet supplemented with 4-PBA showed a significant reduction in weight gain and had reduced fat pad mass, as compared with the high-fat diet alone group. Furthermore, 4-PBA supplementation decreased GRP78 expression in the adipose tissue and lowered plasma triglyceride, glucose, leptin, and adiponectin levels without altering food intake. Taken together, these results suggest that UPR activation contributes to adipogenesis and that blocking its activation with 4-PBA prevents adipocyte differentiation and weight gain in mice.
Collapse
Affiliation(s)
- Sana Basseri
- Department of Medicine, McMaster University, St. Joseph's Healthcare Hamilton and the Henderson Research Centre, Hamilton, Ontario, L8N 4A6, Canada
| | | | | | | |
Collapse
|
30
|
van den Berghe PVE, Stapelbroek JM, Krieger E, de Bie P, van de Graaf SFJ, de Groot REA, van Beurden E, Spijker E, Houwen RHJ, Berger R, Klomp LWJ. Reduced expression of ATP7B affected by Wilson disease-causing mutations is rescued by pharmacological folding chaperones 4-phenylbutyrate and curcumin. Hepatology 2009; 50:1783-95. [PMID: 19937698 DOI: 10.1002/hep.23209] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
UNLABELLED Wilson disease (WD) is an autosomal recessive copper overload disorder of the liver and basal ganglia. WD is caused by mutations in the gene encoding ATP7B, a protein localized to the trans-Golgi network that primarily facilitates hepatic copper excretion. Current treatment comprises reduction of circulating copper by zinc supplementation or copper chelation. Despite treatment, a significant number of patients have neurological deterioration. The aim of this study was to investigate the possibility that defects arising from some WD mutations are ameliorated by drug treatment aimed at improvement of protein folding and restoration of protein function. This necessitated systematic characterization of the molecular consequences of distinct ATP7B missense mutations associated with WD. With the exception of p.S1363F, all mutations tested (p.G85V, p.R778L, p.H1069Q, p.C1104F, p.V1262F, p.G1343V, and p.S1363F) resulted in reduced ATP7B protein expression, whereas messenger RNA abundance was unaffected. Retention of mutant ATP7B in the endoplasmic reticulum, increased protein expression, and normalization of localization after culturing cells at 30 degrees C, and homology modeling suggested that these proteins were misfolded. Four distinct mutations exhibited residual copper export capacity, whereas other mutations resulted in complete disruption of copper export by ATP7B. Treatment with pharmacological chaperones 4-phenylbutyrate (4-PBA) and curcumin, a clinically approved compound, partially restored protein expression of most ATP7B mutants. CONCLUSION These findings might enable novel treatment strategies in WD by directly enhancing the protein expression of mutant ATP7B with residual copper export activity. 1795.).
Collapse
Affiliation(s)
- Peter V E van den Berghe
- Department of Metabolic and Endocrine Diseases, University Medical Center Utrecht, and the Netherlands Metabolomics Center, Utrecht, The Netherlands
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Muller M. Polyphenol cytotoxicity induced by the bacterial toxin pyocyanin: role of NQO1. Free Radic Biol Med 2009; 47:84-91. [PMID: 19362588 DOI: 10.1016/j.freeradbiomed.2009.04.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 04/01/2009] [Accepted: 04/08/2009] [Indexed: 11/20/2022]
Abstract
Pyocyanin is an important bacterial redox-active toxin produced by the opportunistic human pathogen Pseudomonas aeruginosa. The bacterium is a cause of serious infections of the respiratory tract, particularly for those with cystic fibrosis and for those with burn injuries. Pyocyanin induces oxidative stress and causes cells to become prematurely senescent, which compromises tissue remodeling and wound repair. A diverse range of antioxidants have been found useful in preventing oxidant-induced cellular senescence, including quercetin, a common dietary polyphenol. This study evaluated the effectiveness of three common polyphenols (quercetin, (+)-catechin, and (-)-epicatechin) as potential inhibitors of pyocyanin-induced senescence. Whereas at the lowest concentration the polyphenols maintained cellular replicative capacity, in the presence of pyocyanin they unexpectedly displayed concentration-dependent cytotoxicity with a rank order of quercetin>epicatechin>>catechin. On oxidation, polyphenols with B-ring catechol functionality form toxic alkylating quinones that are normally inactivated by cellular antioxidant defense and redox maintenance systems, including reduction by ascorbate and NAD(P)H:quinone oxidoreductase 1 (NQO1). Pyocyanin inhibited cellular NQO1 activity at low micromolar concentrations, but the presence of exogenous ascorbate eliminated pyocyanin-induced polyphenol cytotoxicity. These data indicate that pyocyanin compromises cellular redox maintenance systems, leaving cells susceptible to the adverse effects of otherwise nontoxic redox-active compounds.
Collapse
Affiliation(s)
- Michael Muller
- Centre for Education and Research on Ageing, University of Sydney, Concord RG Hospital, Sydney, NSW 2139, Australia.
| |
Collapse
|
32
|
Lawless MW, Norris S, O'Byrne KJ, Gray SG. Targeting histone deacetylases for the treatment of disease. J Cell Mol Med 2008; 13:826-52. [PMID: 19175682 PMCID: PMC3823402 DOI: 10.1111/j.1582-4934.2008.00571.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The ‘histone code’ is a well-established hypothesis describing the idea that specific patterns of post-translational modifications to histones act like a molecular ‘code’ recognized and used by non-histone proteins to regulate specific chromatin functions. One modification, which has received significant attention, is that of histone acetylation. The enzymes that regulate this modification are described as lysine acetyltransferases or KATs, and histone deacetylases or HDACs. Due to their conserved catalytic domain HDACs have been actively targeted as a therapeutic target. The pro-inflammatory environment is increasingly being recognized as a critical element for both degenerative diseases and cancer. The present review will discuss the current knowledge surrounding the clinical potential and current development of histone deacetylases for the treatment of diseases for which a pro-inflammatory environment plays important roles, and the molecular mechanisms by which such inhibitors may play important functions in modulating the pro-inflammatory environment.
Collapse
Affiliation(s)
- M W Lawless
- Centre for Liver Disease, School of Medicine and Medical Science, Mater Misericordiae University Hospital - University College Dublin, Dublin, Ireland
| | | | | | | |
Collapse
|
33
|
|
34
|
Schmidt A, Hughes LK, Cai Z, Mendes F, Li H, Sheppard DN, Amaral MD. Prolonged treatment of cells with genistein modulates the expression and function of the cystic fibrosis transmembrane conductance regulator. Br J Pharmacol 2008; 153:1311-23. [PMID: 18223673 PMCID: PMC2275442 DOI: 10.1038/sj.bjp.0707663] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 11/14/2007] [Accepted: 12/04/2007] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE Cystic fibrosis (CF) is caused by dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel. In the search for new CF therapies, small molecules have been identified that rescue the defective channel gating of CF mutants (termed CFTR potentiators). Here, we investigate the long-term effects of genistein, the best-studied CFTR potentiator, on the expression and function of CFTR. EXPERIMENTAL APPROACH We pre-treated baby hamster kidney (BHK) cells expressing wild-type or F508del-CFTR (the most common CF mutant) with concentrations of genistein that potentiate (30 microM) or inhibit (100 microM) CFTR function for 2 or 24 h at 37 degrees C before examining CFTR maturation, expression and single-channel activity. KEY RESULTS Using the iodide efflux technique, we found that genistein pre-treatment failed to restore function to F508del-CFTR, but altered that of wild-type CFTR. Pre-treatment of cells with genistein for 2 h had little effect on CFTR processing, whereas pre-treatment for 24 h either augmented (30 microM genistein) or impaired (100 microM genistein) CFTR maturation. Using immunocytochemistry, we found that all genistein pre-treatments increased the localization of CFTR protein to the cell surface. However, following the incubation of cells with genistein (100 microM) for 2 h, individual CFTR Cl(-) channels exhibited characteristics of channel block upon channel activation. CONCLUSIONS AND IMPLICATIONS Genistein pre-treatment alters the maturation, cell surface expression and single-channel function of CFTR in ways distinct from its acute effects. Thus, CFTR potentiators have the potential to influence CFTR by mechanisms distinct from their effects on channel gating.
Collapse
Affiliation(s)
- A Schmidt
- Centre of Human Genetics, National Institute of Health Lisboa, Portugal
- Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisboa Lisboa, Portugal
| | - L K Hughes
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol Bristol, UK
| | - Z Cai
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol Bristol, UK
| | - F Mendes
- Centre of Human Genetics, National Institute of Health Lisboa, Portugal
- Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisboa Lisboa, Portugal
| | - H Li
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol Bristol, UK
| | - D N Sheppard
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol Bristol, UK
| | - M D Amaral
- Centre of Human Genetics, National Institute of Health Lisboa, Portugal
- Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisboa Lisboa, Portugal
| |
Collapse
|
35
|
Roth J, Yam GHF, Fan J, Hirano K, Gaplovska-Kysela K, Le Fourn V, Guhl B, Santimaria R, Torossi T, Ziak M, Zuber C. Protein quality control: the who's who, the where's and therapeutic escapes. Histochem Cell Biol 2008; 129:163-77. [PMID: 18075753 PMCID: PMC2228381 DOI: 10.1007/s00418-007-0366-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2007] [Indexed: 01/01/2023]
Abstract
In cells the quality of newly synthesized proteins is monitored in regard to proper folding and correct assembly in the early secretory pathway, the cytosol and the nucleoplasm. Proteins recognized as non-native in the ER will be removed and degraded by a process termed ERAD. ERAD of aberrant proteins is accompanied by various changes of cellular organelles and results in protein folding diseases. This review focuses on how the immunocytochemical labeling and electron microscopic analyses have helped to disclose the in situ subcellular distribution pattern of some of the key machinery proteins of the cellular protein quality control, the organelle changes due to the presence of misfolded proteins, and the efficiency of synthetic chaperones to rescue disease-causing trafficking defects of aberrant proteins.
Collapse
Affiliation(s)
- Jürgen Roth
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
| | - Gary Hin-Fai Yam
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, University Eye Centre, Mongkok, Kowloon Hong Kong
| | - Jingyu Fan
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
- Department of Biophysics, Peking University Health Science Center, 100083 Beijing, P. R. China
| | - Kiyoko Hirano
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
- The Noguchi Institute, 1-8-1 Kaga, Itabashi, Tokyo 173-0003 Japan
| | - Katarina Gaplovska-Kysela
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
| | - Valerie Le Fourn
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
| | - Bruno Guhl
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
| | - Roger Santimaria
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
| | - Tania Torossi
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
| | - Martin Ziak
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
| | - Christian Zuber
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, 8091 Zurich, Switzerland
| |
Collapse
|
36
|
Robert R, Carlile GW, Pavel C, Liu N, Anjos SM, Liao J, Luo Y, Zhang D, Thomas DY, Hanrahan JW. Structural Analog of Sildenafil Identified as a Novel Corrector of the F508del-CFTR Trafficking Defect. Mol Pharmacol 2007; 73:478-89. [DOI: 10.1124/mol.107.040725] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
|
37
|
Prulière-Escabasse V, Planès C, Escudier E, Fanen P, Coste A, Clerici C. Modulation of epithelial sodium channel trafficking and function by sodium 4-phenylbutyrate in human nasal epithelial cells. J Biol Chem 2007; 282:34048-57. [PMID: 17890229 DOI: 10.1074/jbc.m702384200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sodium 4-phenylbutyrate (4-PBA) has been shown to correct the cellular trafficking of several mutant or nonmutant plasma membrane proteins such as cystic fibrosis transmembrane conductance regulator through the expression of 70-kDa heat shock proteins. The objective of the study was to determine whether 4-PBA may influence the functional expression of epithelial sodium channels (ENaC) in human nasal epithelial cells (HNEC). Using primary cultures of HNEC, we demonstrate that 4-PBA (5 mm for 6 h) markedly stimulated amiloride-sensitive sodium channel activity and that this was related to an increased abundance of alpha-, beta-, and gamma-ENaC subunits in the apical membrane. The increase in ENaC cell surface expression (i) was due to insertion of newly ENaC subunits as determined by brefeldin A experiments and (ii) was not associated with cell surface retention of ENaC subunits because endocytosis of ENaC subunits was unchanged. In addition, we find that ENaC co-immunoprecipitated with the heat shock protein constitutively expressed Hsc70, that has been reported to modulate ENaC trafficking, and that 4-PBA decreased Hsc70 protein level. Finally, we report that in cystic fibrosis HNEC obtained from two cystic fibrosis patients, 4-PBA increased functional expression of ENaC as demonstrated by the increase in amiloride-sensitive sodium transport and in alpha-, beta-, and gamma-ENaC subunit expression in the apical membrane. Our results suggest that in HNEC, 4-PBA increases the functional expression of ENaC through the insertion of new alpha-, beta-, and gamma-ENaC subunits into the apical membrane and also suggest that 4-PBA could modify ENaC trafficking by reducing Hsc70 protein expression.
Collapse
|
38
|
Yam GHF, Roth J, Zuber C. 4-Phenylbutyrate rescues trafficking incompetent mutant alpha-galactosidase A without restoring its functionality. Biochem Biophys Res Commun 2007; 360:375-80. [PMID: 17592721 DOI: 10.1016/j.bbrc.2007.06.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Accepted: 06/08/2007] [Indexed: 10/23/2022]
Abstract
Fabry disease is a lysosomal storage disorder caused by deficiency of alpha-galactosidase A. Most mutant enzyme is catalytically active but due to misfolding retained in the endoplasmic reticulum. We have tested 4-phenylbutyrate for its potential to rescue various trafficking incompetent mutant alpha-galactosidase A. Although we found that the trafficking blockade for endoplasmic reticulum-retained mutant alpha-Gal A was released, neither a mature enzyme was detectable in transgenic mice fibroblasts nor a reversal of lysosomal Gb3 storage in fibroblasts from Fabry patients could be observed. Because of lack of functionality of rescued mutant alpha-galactosidase A, 4-phenylbutyrate seems to be of limited use as a chemical chaperone for Fabry disease.
Collapse
Affiliation(s)
- Gary Hin-Fai Yam
- Division of Cell and Molecular Pathology, Department of Pathology, University of Zurich, CH-8091 Zürich, Switzerland
| | | | | |
Collapse
|
39
|
Abstract
Animal models of cystic fibrosis (CF) are powerful tools that enable the study of the mechanisms and complexities of human disease. Murine models have several intrinsic advantages compared with other animal models, including lower cost, maintenance, and rapid reproduction rate. Mice can be easily genetically manipulated by making transgenic or knockout mice, or by backcrossing to well-defined inbred strains in a reasonably short period of time. However, anatomic and immunologic differences between mice and humans mean that murine models have inherent limitations that must be considered when interpreting the results obtained from experimental models and applying these to the pathogenesis of CF disease in humans. This review will focus on the different CF mouse models available that represent diverse phenotypes observed in humans with CF and that can help researchers elucidate the diverse functions of the CFTR protein.
Collapse
Affiliation(s)
- Claudine Guilbault
- McGill Centre for the Study of Host Resistance, McGill University Health Center Research Institute, Montreal, Quebec, Canada
| | | | | | | |
Collapse
|
40
|
Rubenstein RC. Targeted therapy for cystic fibrosis: cystic fibrosis transmembrane conductance regulator mutation-specific pharmacologic strategies. Mol Diagn Ther 2006; 10:293-301. [PMID: 17022692 DOI: 10.1007/bf03256204] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cystic fibrosis (CF) results from the absence or dysfunction of a single protein, the CF transmembrane conductance regulator (CFTR). CFTR plays a critical role in the regulation of ion transport in a number of exocrine epithelia. Improvement or restoration of CFTR function, where it is deficient, should improve the CF phenotype. There are >1000 reported disease-causing mutations of the CFTR gene. Recent investigations have afforded a better understanding of the mechanism of dysfunction of many of these mutant CFTRs, and have allowed them to be classified according to their mechanism of dysfunction. These data, as well as an enhanced understanding of the role of CFTR in regulating epithelial ion transport, have led to the development of therapeutic strategies based on pharmacologic enhancement or repair of mutant CFTR dysfunction. The strategy, termed 'protein repair therapy', is aimed at improving the regulation of epithelial ion transport by mutant CFTRs in a mutation-specific fashion. The grouping of CFTR gene mutations, according to mechanism of dysfunction, yields some guidance as to which pharmacologic repair agents may be useful for specific CFTR mutations. Recent data has suggested that combinations of pharmacologic repair agents may be necessary to obtain clinically meaningful CFTR repair. Nevertheless, such strategies to improve mutant CFTR function hold great promise for the development of novel therapies aimed at correcting the underlying pathophysiology of CF.
Collapse
Affiliation(s)
- Ronald C Rubenstein
- Division of Pulmonary Medicine and Cystic Fibrosis Center, Children's Hospital of Philadelphia, PA 19104, USA.
| |
Collapse
|
41
|
Woltjer RL, McMahan W, Milatovic D, Kjerulf JD, Shie FS, Rung LG, Montine KS, Montine TJ. Effects of chemical chaperones on oxidative stress and detergent-insoluble species formation following conditional expression of amyloid precursor protein carboxy-terminal fragment. Neurobiol Dis 2006; 25:427-37. [PMID: 17141508 DOI: 10.1016/j.nbd.2006.10.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2006] [Revised: 09/29/2006] [Accepted: 10/11/2006] [Indexed: 11/19/2022] Open
Abstract
Oxidative stress, protein misfolding, protein complex formation, and detergent insolubility are biochemical features of Alzheimer's disease (AD). We tested the cause-and-effect relationships among these using MC65 human neuroblastoma cells that exhibit toxicity upon conditional expression of carboxy-terminal fragments (CTFs) of the human amyloid precursor protein (APP). Treatments with three different antioxidants (alpha-tocopherol, N-acetyl cysteine, and alpha-lipoic acid) or three different compounds (glycerol, trimethylamine-N-oxide, and 4-phenylbutyric acid) that have been described to have a "chemical chaperone" function in promoting protein folding all had a protective effect on MC65 cells and decreased markers of oxidative damage and accumulation of high molecular weight amyloid (A) beta-immunoreactive (IR) species. However, chaperones partially reduced detergent insolubility of the remaining Abeta-IR species, while antioxidants did not. These results suggest that protein misfolding associated with overexpression of APP CTFs promotes oxidative stress and cytotoxicity and contributes to formation of detergent-insoluble species that appear unrelated to cytotoxicity.
Collapse
Affiliation(s)
- Randall L Woltjer
- Department of Pathology, University of Washington, Box 359645, Harborview Medical Center, 300 Ninth Avenue, Seattle, WA 98104, USA.
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Sousa M, Ousingsawat J, Seitz R, Puntheeranurak S, Regalado A, Schmidt A, Grego T, Jansakul C, Amaral MD, Schreiber R, Kunzelmann K. An Extract from the Medicinal Plant Phyllanthus acidus and Its Isolated Compounds Induce Airway Chloride Secretion: A Potential Treatment for Cystic Fibrosis. Mol Pharmacol 2006; 71:366-76. [PMID: 17065237 DOI: 10.1124/mol.106.025262] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
According to previous reports, flavonoids and nutraceuticals correct defective electrolyte transport in cystic fibrosis (CF) airways. Traditional medicinal plants from China and Thailand contain phytoflavonoids and other bioactive compounds. We examined herbal extracts of the common Thai medicinal euphorbiaceous plant Phyllanthus acidus for their potential effects on epithelial transport. Functional assays by Ussing chamber, patch-clamping, double-electrode voltage-clamp and Ca2+ imaging demonstrate activation of Cl- secretion and inhibition of Na+ absorption by P. acidus. No cytotoxic effects of P. acidus could be detected. Mucosal application of P. acidus to native mouse trachea suggested transient and steady-state activation of Cl- secretion by increasing both intracellular Ca2+ and cAMP. These effects were mimicked by a mix of the isolated components adenosine, kaempferol, and hypogallic acid. Additional experiments in human airway cells and CF transmembrane conductance regulator (CFTR)-expressing BHK cells and Xenopus laevis oocytes confirm the results obtained in native tissues. Cl- secretion was also induced in tracheas of CF mice homozygous for Phe508del-CFTR and in Phe508del-CFTR homozygous human airway epithelial cells. Taken together, P. acidus corrects defective electrolyte transport in CF airways by parallel mechanisms including 1) increasing the intracellular levels of second messengers cAMP and Ca2+, thereby activating Ca2+-dependent Cl- channels and residual CFTR-Cl- conductance; 2) stimulating basolateral K+ channels; 3) redistributing cellular localization of CFTR; 4) directly activating CFTR; and 5) inhibiting ENaC through activation of CFTR. These combinatorial effects on epithelial transport may provide a novel complementary nutraceutical treatment for the CF lung disease.
Collapse
Affiliation(s)
- Marisa Sousa
- Institut für Physiologie, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg, Germany
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Vij N, Fang S, Zeitlin PL. Selective inhibition of endoplasmic reticulum-associated degradation rescues DeltaF508-cystic fibrosis transmembrane regulator and suppresses interleukin-8 levels: therapeutic implications. J Biol Chem 2006; 281:17369-17378. [PMID: 16621797 DOI: 10.1074/jbc.m600509200] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endoplasmic reticulum (ER)-associated degradation (ERAD) is the major quality control pathway of the cell. The most common disease-causing protein folding mutation, DeltaF508-cystic fibrosis transmembrane regulator (CFTR), is destroyed by ERAD to cause cystic fibrosis (CF). p97/valosin-containing protein (VCP) physically interacts with gp78/autocrine motility factor receptor to couple ubiquitination, retrotranslocation, and proteasome degradation of misfolded proteins. We show here that p97/VCP and gp78 form complexes with CFTR during translocation from the ER for degradation by the cytosolic proteasome. Interference in the VCP-CFTR complex promoted accumulation of immature CFTR in the ER and partial rescue of functional chloride channels to the cell surface. Moreover, under these conditions, interleukin-8 (IL8), the expression of which is regulated by the proteasome, was reduced. Inhibition of the proteasome with bortezomib (PS-341/Velcade) also rescued CFTR, but with less efficiency, and suppressed NFkappaB-mediated IL8 activation. The inhibition of the major stress-inducible transcription factor CHOP (CCAAT/enhancer-binding protein homologous protein)/GADD153 together with bortezomib was most effective in repressing NFkappaB-mediated IL8 activation compared with interference of VCP, MLN-273 (proteasome inhibitor), or 4-phenylbutyrate (histone deacetylase inhibitor). Immunoprecipitation of DeltaF508-CFTR from primary CF bronchial epithelial cells confirmed the interaction with VCP and associated chaperones in CF. We conclude that VCP is an integral component of ERAD and cellular stress pathways induced by the unfolded protein response and may be central to the efficacy of CF drugs that target the ubiquitin-proteasome pathway.
Collapse
Affiliation(s)
- Neeraj Vij
- Division of Pediatric Respiratory Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland 21287
| | - Shengyun Fang
- Medical Biotechnology Center, University of Maryland Biotechnology Institute, Baltimore, Maryland 21201
| | - Pamela L Zeitlin
- Division of Pediatric Respiratory Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland 21287.
| |
Collapse
|
44
|
Nguyen TD, Kim US, Perrine SP. Novel short chain fatty acids restore chloride secretion in cystic fibrosis. Biochem Biophys Res Commun 2006; 342:245-52. [PMID: 16472777 DOI: 10.1016/j.bbrc.2006.01.127] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 01/26/2006] [Indexed: 10/25/2022]
Abstract
Phenylalanine deletion at position 508 of the cystic fibrosis transmembrane conductance regulator (DeltaF508-CFTR), the most common mutation in cystic fibrosis (CF), causes a misfolded protein exhibiting partial chloride conductance and impaired trafficking to the plasma membrane. 4-Phenylbutyrate corrects defective DeltaF508-CFTR trafficking in vitro, but is not clinically efficacious. From a panel of short chain fatty acid derivatives, we showed that 2,2-dimethyl-butyrate (ST20) and alpha-methylhydrocinnamic acid (ST7), exhibiting high oral bioavailability and sustained plasma levels, correct the DeltaF508-CFTR defect. Pre-incubation (>or=6h) of CF IB3-1 airway cells with >or=1mM ST7 or ST20 restored the ability of 100microM forskolin to stimulate an (125)I(-) efflux. This efflux was fully inhibited by NPPB, DPC, or glibenclamide, suggesting mediation through CFTR. Partial inhibition by DIDS suggests possible contribution from an additional Cl(-) channel regulated by CFTR. Thus, ST7 and ST20 offer treatment potential for CF caused by the DeltaF508 mutation.
Collapse
Affiliation(s)
- Toan D Nguyen
- Division of Gastroenterology, Department of Medicine, University of Washington and VA Puget Sound Health Care System, Seattle, WA 98108, USA.
| | | | | |
Collapse
|
45
|
Cheong N, Madesh M, Gonzales LW, Zhao M, Yu K, Ballard PL, Shuman H. Functional and trafficking defects in ATP binding cassette A3 mutants associated with respiratory distress syndrome. J Biol Chem 2006; 281:9791-800. [PMID: 16415354 DOI: 10.1074/jbc.m507515200] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Members of the ATP binding cassette (ABC) protein superfamily actively transport a wide range of substrates across cell and intracellular membranes. Mutations in ABCA3, a member of the ABCA subfamily with unknown function, lead to fatal respiratory distress syndrome (RDS) in the newborn. Using cultured human lung cells, we found that recombinant wild-type hABCA3 localized to membranes of both lysosomes and lamellar bodies, which are the intracellular storage organelles for surfactant. In contrast, hABCA3 with mutations linked to RDS failed to target to lysosomes and remained in the endoplasmic reticulum as unprocessed forms. Treatment of those cells with the chemical chaperone sodium 4-phenylbutyrate could partially restore trafficking of mutant ABCA3 to lamellar body-like structures. Expression of recombinant ABCA3 in non-lung human embryonic kidney 293 cells induced formation of lamellar body-like vesicles that contained lipids. Small interfering RNA knockdown of endogenous hABCA3 in differentiating human fetal lung alveolar type II cells resulted in abnormal, lamellar bodies comparable with those observed in vivo with mutant ABCA3. Silencing of ABCA3 expression also reduced vesicular uptake of surfactant lipids phosphatidylcholine, sphingomyelin, and cholesterol but not phosphatidylethanolamine. We conclude that ABCA3 is required for lysosomal loading of phosphatidylcholine and conversion of lysosomes to lamellar body-like structures.
Collapse
Affiliation(s)
- Naeun Cheong
- Department of Physiology, Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6068, USA
| | | | | | | | | | | | | |
Collapse
|
46
|
Kerem E. Pharmacological induction of CFTR function in patients with cystic fibrosis: mutation-specific therapy. Pediatr Pulmonol 2005; 40:183-96. [PMID: 15880796 DOI: 10.1002/ppul.20200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
CFTR mutations cause defects of CFTR protein production and function by different molecular mechanisms. Mutations can be classified according to the mechanisms by which they disrupt CFTR function. This understanding of the different molecular mechanisms of CFTR dysfunction provides the scientific basis for the development of targeted drugs for mutation-specific therapy of cystic fibrosis (CF). Class I mutations are nonsense mutations that result in the presence of a premature stop codon that leads to the production of unstable mRNA, or the release from the ribosome of a short, truncated protein that is not functional. Aminoglycoside antibiotics can suppress premature termination codons by disrupting translational fidelity and allowing the incorporation of an amino acid, thus permitting translation to continue to the normal termination of the transcript. Class II mutations cause impairment of CFTR processing and folding in the Golgi. As a result, the mutant CFTR is retained in the endoplasmic reticulum (ER) and eventually targeted for degradation by the quality control mechanisms. Chemical and molecular chaperones such as sodium-4-phenylbutyrate can stabilize protein structure, and allow it to escape from degradation in the ER and be transported to the cell membrane. Class III mutations disrupt the function of the regulatory domain. CFTR is resistant to phosphorylation or adenosine tri-phosphate (ATP) binding. CFTR activators such as alkylxanthines (CPX) and the flavonoid genistein can overcome affected ATP binding through direct binding to a nucleotide binding fold. In patients carrying class IV mutations, phosphorylation of CFTR results in reduced chloride transport. Increases in the overall cell surface content of these mutants might overcome the relative reduction in conductance. Alternatively, restoring native chloride pore characteristics pharmacologically might be effective. Activators of CFTR at the plasma membrane may function by promoting CFTR phosphorylation, by blocking CFTR dephosphorylation, by interacting directly with CFTR, and/or by modulation of CFTR protein-protein interactions. Class V mutations affect the splicing machinery and generate both aberrantly and correctly spliced transcripts, the levels of which vary among different patients and among different organs of the same patient. Splicing factors that promote exon inclusion or factors that promote exon skipping can promote increases of correctly spliced transcripts, depending on the molecular defect. Inconsistent results were reported regarding the required level of corrected or mutated CFTR that had to be reached in order to achieve normal function.
Collapse
Affiliation(s)
- Eitan Kerem
- Department of Pediatrics and Cystic Fibrosis Center, Hadassah University Hospital, Jerusalem, Israel.
| |
Collapse
|
47
|
Moskowitz SM, Gibson RL, Effmann EL. Cystic fibrosis lung disease: genetic influences, microbial interactions, and radiological assessment. Pediatr Radiol 2005; 35:739-57. [PMID: 15868140 DOI: 10.1007/s00247-005-1445-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2004] [Revised: 01/20/2005] [Accepted: 01/27/2005] [Indexed: 10/25/2022]
Abstract
Cystic fibrosis (CF) is a multiorgan disease caused by mutation of the CF transmembrane conductance regulator (CFTR) gene. Obstructive lung disease is the predominant cause of morbidity and mortality; thus, most efforts to improve outcomes are directed toward slowing or halting lung-disease progression. Current therapies, such as mucolytics, airway clearance techniques, bronchodilators, and antibiotics, aim to suppress airway inflammation and the processes that stimulate it, namely, retention and infection of mucus plaques at the airway surface. New approaches to therapy that aim to ameliorate specific CFTR mutations or mutational classes by restoring normal expression or function are being investigated. Because of its sensitivity in detecting changes associated with early airway obstruction and regional lung disease, high-resolution CT (HRCT) complements pulmonary function testing in defining disease natural history and measuring response to both conventional and experimental therapies. In this review, perspectives on the genetics and microbiology of CF provide a context for understanding the increasing importance of HRCT and other imaging techniques in assessing CF therapies.
Collapse
Affiliation(s)
- Samuel M Moskowitz
- Department of Pediatrics, University of Washington School of Medicine and Children's Hospital and Regional Medical Center, Seattle, WA 98105, USA
| | | | | |
Collapse
|
48
|
Abstract
PURPOSE OF REVIEW Cystic fibrosis results from disruption of the biosynthesis or function of the cystic fibrosis transmembrane conductance regulator. Cystic fibrosis transmembrane conductance regulator plays a critical role in the regulation of epithelial ion transport. Restoration of cystic fibrosis transmembrane conductance regulator function should improve the cystic fibrosis phenotype. RECENT FINDINGS Recent investigations affording a better understanding of the mechanism of dysfunction of mutant cystic fibrosis transmembrane conductance regulators, as well as the roles of cystic fibrosis transmembrane conductance regulator in regulating epithelial ion transport, have led to development of therapeutic strategies based on repair or bypass of mutant cystic fibrosis transmembrane conductance regulator dysfunction. The former strategy, coined 'protein repair therapy,' is aimed at improving or restoring the function of mutant cystic fibrosis transmembrane conductance regulators, whereas the latter approach aims to augment epithelial ion transport to compensate for the absent function mutant cystic fibrosis transmembrane conductance regulator. SUMMARY Strategies to improve mutant cystic fibrosis transmembrane conductance regulator function or to bypass mutant cystic fibrosis transmembrane conductance regulator function hold great promise for development of novel therapies aimed at correcting the underlying pathophysiology of cystic fibrosis.
Collapse
Affiliation(s)
- Ronald C Rubenstein
- Department of Pediatrics, University of Pennsylvania School of Medicine, Children's Hospital of Philadelphia, Pennsylvania 19104, USA.
| |
Collapse
|
49
|
Lu M, Staszewski L, Echeverri F, Xu H, Moyer BD. Endoplasmic reticulum degradation impedes olfactory G-protein coupled receptor functional expression. BMC Cell Biol 2004; 5:34. [PMID: 15369603 PMCID: PMC520810 DOI: 10.1186/1471-2121-5-34] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Accepted: 09/15/2004] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Research on olfactory G-protein coupled receptors (GPCRs) has been severely impeded by poor functional expression in heterologous systems. Previously, we demonstrated that inefficient olfactory receptor (OR) expression at the plasma membrane is attributable, in part, to degradation of endoplasmic reticulum (ER)-retained ORs by the ubiquitin-proteasome system and sequestration of ORs in ER aggregates that are degraded by autophagy. Thus, experiments were performed to test the hypothesis that attenuation of ER degradation improves OR functional expression in heterologous cells. RESULTS To develop means to increase the functional expression of ORs, we devised an approach to measure activation of the mOREG OR (Unigene # Mm.196680; Olfr73) through coupling to an olfactory cyclic nucleotide-gated cation channel (CNG). This system, which utilizes signal transduction machinery coupled to OR activation in native olfactory sensory neurons, was used to demonstrate that degradation, both by the ubiquitin-proteasome system and autophagy, limits mOREG functional expression. The stimulatory effects of proteasome and autophagy inhibitors on mOREG function required export from the ER and trafficking through the biosynthetic pathway. CONCLUSIONS These findings demonstrate that poor functional expression of mOREG in heterologous cells is improved by blocking proteolysis. Inhibition of ER degradation may improve the function of other ORs and assist future efforts to elucidate the molecular basis of odor discrimination.
Collapse
Affiliation(s)
- Min Lu
- Senomyx, Inc., 11099 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Lena Staszewski
- Senomyx, Inc., 11099 North Torrey Pines Road, La Jolla, CA 92037, USA
- Present Address: Kalypsys, Inc., 10420 Wateridge Circle, San Diego, CA 92121 USA
| | | | - Hong Xu
- Senomyx, Inc., 11099 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Bryan D Moyer
- Senomyx, Inc., 11099 North Torrey Pines Road, La Jolla, CA 92037, USA
| |
Collapse
|