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Teafatiller T, Perez O, Kitazawa M, Agrawal A, Subramanian VS. Nedd4-1 regulates human sodium-dependent vitamin C transporter-2 functional expression in neuronal and epithelial cells. J Nutr Biochem 2023; 120:109413. [PMID: 37423323 DOI: 10.1016/j.jnutbio.2023.109413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 06/12/2023] [Accepted: 07/05/2023] [Indexed: 07/11/2023]
Abstract
The ubiquitin-proteasomal pathway regulates the functional expression of many membrane transporters in a variety of cellular systems. Nothing is currently known about the role of ubiquitin E3 ligase, neural precursor cell-expressed developmentally down-regulated gene 4 (Nedd4-1) and the proteasomal degradation pathway in regulating human vitamin C transporter-2 (hSVCT2) in neuronal cells. hSVCT2 mediates the uptake of ascorbic acid (AA) and is the predominantly expressed vitamin C transporter isoform in neuronal systems. Therefore, we addressed this knowledge gap in our study. Analysis of mRNA revealed markedly higher expression of Nedd4-1 in neuronal samples than that of Nedd4-2. Interestingly, Nedd4-1 expression in the hippocampus was higher in patients with Alzheimer's disease (AD) and age-dependently increased in the J20 mouse model of AD. The interaction of Nedd4-1 and hSVCT2 was confirmed by coimmunoprecipitation and colocalization. While the coexpression of Nedd4-1 with hSVCT2 displayed a significant decrease in AA uptake, siRNA-mediated knockdown of Nedd4-1 expression up-regulated the AA uptake. Further, we mutated a classical Nedd4 protein interacting motif ("PPXY") within the hSVCT2 polypeptide and observed markedly decreased AA uptake due to the intracellular localization of the mutated hSVCT2. Also, we determined the role of the proteasomal degradation pathway in hSVCT2 functional expression in SH-SY5Y cells and the results indicated that the proteasomal inhibitor (MG132) significantly up-regulated the AA uptake and hSVCT2 protein expression level. Taken together, our findings show that the regulation of hSVCT2 functional expression is at least partly mediated by the Nedd4-1 dependent ubiquitination and proteasomal pathways.
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Affiliation(s)
- Trevor Teafatiller
- Department of Medicine, University of California, Irvine, California, USA
| | - Oasis Perez
- Department of Medicine, University of California, Irvine, California, USA
| | - Masashi Kitazawa
- Department of Environmental and Occupational Health, University of California, Irvine, California, USA
| | - Anshu Agrawal
- Department of Medicine, University of California, Irvine, California, USA
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Leischner C, Marongiu L, Piotrowsky A, Niessner H, Venturelli S, Burkard M, Renner O. Relevant Membrane Transport Proteins as Possible Gatekeepers for Effective Pharmacological Ascorbate Treatment in Cancer. Antioxidants (Basel) 2023; 12:antiox12040916. [PMID: 37107291 PMCID: PMC10135768 DOI: 10.3390/antiox12040916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/23/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
Despite the increasing number of newly diagnosed malignancies worldwide, therapeutic options for some tumor diseases are unfortunately still limited. Interestingly, preclinical but also some clinical data suggest that the administration of pharmacological ascorbate seems to respond well, especially in some aggressively growing tumor entities. The membrane transport and channel proteins are highly relevant for the use of pharmacological ascorbate in cancer therapy and are involved in the transfer of active substances such as ascorbate, hydrogen peroxide, and iron that predominantly must enter malignant cells to induce antiproliferative effects and especially ferroptosis. In this review, the relevant conveying proteins from cellular surfaces are presented as an integral part of the efficacy of pharmacological ascorbate, considering the already known genetic and functional features in tumor tissues. Accordingly, candidates for diagnostic markers and therapeutic targets are mentioned.
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Affiliation(s)
- Christian Leischner
- Institute of Nutritional Sciences, Department of Nutritional Biochemistry, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
| | - Luigi Marongiu
- Institute of Nutritional Sciences, Department of Nutritional Biochemistry, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
- Department of Internal Medicine VIII, University Hospital Tuebingen, Otfried-Mueller-Straße 10, 72076 Tuebingen, Germany
| | - Alban Piotrowsky
- Institute of Nutritional Sciences, Department of Nutritional Biochemistry, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
| | - Heike Niessner
- Department of Dermatology, Division of Dermatooncology, University of Tuebingen, Liebermeisterstraße 25, 72076 Tuebingen, Germany
- Cluster of Excellence iFIT (EXC 2180) "Image Guided and Functionally Instructed Tumor Therapies", 72076 Tuebingen, Germany
| | - Sascha Venturelli
- Institute of Nutritional Sciences, Department of Nutritional Biochemistry, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
- Institute of Physiology, Department of Vegetative and Clinical Physiology, University of Tuebingen, Wilhelmstraße 56, 72074 Tuebingen, Germany
| | - Markus Burkard
- Institute of Nutritional Sciences, Department of Nutritional Biochemistry, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
| | - Olga Renner
- Institute of Nutritional Sciences, Department of Nutritional Biochemistry, University of Hohenheim, Garbenstraße 30, 70599 Stuttgart, Germany
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Rashid MA, Lin-Moshier Y, Gunaratne GS, Subramanian S, Marchant JS, Subramanian VS. Vitamin C transport in neurons and epithelia is regulated by secretory carrier-associated membrane protein-2 (SCAMP2). Int J Biol Macromol 2023; 230:123205. [PMID: 36632962 DOI: 10.1016/j.ijbiomac.2023.123205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/28/2022] [Accepted: 01/05/2023] [Indexed: 01/11/2023]
Abstract
The human sodium-dependent vitamin C transporter-1 (hSVCT1) is localized at the apical membrane domain of polarized intestinal and renal epithelial cells to mediate ascorbic acid (AA) uptake. Currently, little is known about the array of interacting proteins that aid hSVCT1 trafficking and functional expression at the cell surface. Here we used an affinity tagging ('One-STrEP') and proteomic approach to identify hSVCT1 interacting proteins, which resolved secretory carrier-associated membrane protein-2 (SCAMP2) as a novel accessary protein partner. SCAMP2 was validated as an accessory protein by co-immunoprecipitation with hSVCT1. Co-expression of hSVCT1 and SCAMP2 in HEK-293 cells revealed both proteins co-localized in intracellular structures and at the plasma membrane. Functionally, over-expression of SCAMP2 potentiated 14C-AA uptake, and reciprocally silencing endogenous SCAMP2 decreased 14C-AA uptake. Finally, knockdown of endogenous hSVCT1 or SCAMP2 impaired differentiation of human-induced pluripotent stem cells (hiPSCs) toward a neuronal fate. These results establish SCAMP2 as a novel hSVCT1 accessary protein partner that regulates AA uptake in absorptive epithelia and during neurogenesis.
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Affiliation(s)
- Mohammad A Rashid
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, WI 53226, United States
| | - Yaping Lin-Moshier
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, WI 53226, United States
| | - Gihan S Gunaratne
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, WI 53226, United States
| | - Sreya Subramanian
- Department of Medicine, University of California, Irvine, CA 92697, United States
| | - Jonathan S Marchant
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, WI 53226, United States
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Teafatiller T, Subramanian S, Marquez FE, Kitazawa M, Subramanian VS. Valproic acid upregulates sodium-dependent vitamin C transporter-2 functional expression in neuronal cells. Life Sci 2022; 308:120944. [PMID: 36096242 DOI: 10.1016/j.lfs.2022.120944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 08/29/2022] [Accepted: 09/06/2022] [Indexed: 01/19/2023]
Abstract
Neuronal uptake of ascorbic acid (AA) in humans occurs via the human sodium-dependent vitamin C transporter-2 (hSVCT2). Recent studies show that a significantly lower level of vitamin C is present in the blood of epileptic patients. Consequently, focused studies investigating the involved molecular mechanisms for hSVCT2 regulation are vital to enhance vitamin C body homeostasis. Currently, little is known about the role of valproic acid (VPA), a drug utilized to treat epilepsy and a class I histone deacetylase inhibitor (HDACi), on AA uptake in neuronal systems. Thus, this study aims to examine the effect of VPA on hSVCT2 functional expression in neuronal cells. VPA treatment upregulated the AA uptake and this increased AA uptake was associated with a significant increase in hSVCT2 expression and SLC23A2 promoter activity in SH-SY5Y cells. Knockdown of HDAC2, a predominant isoform in neuronal systems, significantly increased hSVCT2 functional expression. VPA treatment in mice displayed increased mouse (m)SVCT2 protein, mRNA and heterogenous nuclear RNA (hnRNA) expression in the brain. In addition, Yin Yang-1 (YY1), a transcription factor that drives the SLC23A2 promoter activity, protein and mRNA expression levels were markedly upregulated in VPA-treated SH-SY5Y cells and mice brain. Together, our findings suggest that VPA upregulates the functional expression of SVCT2 via HDAC2 and transcriptional mechanism(s).
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Affiliation(s)
- Trevor Teafatiller
- Department of Medicine, University of California, Irvine, CA 92697, United States of America
| | - Sreya Subramanian
- Department of Medicine, University of California, Irvine, CA 92697, United States of America
| | - Felerico E Marquez
- Department of Medicine, University of California, Irvine, CA 92697, United States of America
| | - Masashi Kitazawa
- Department of Medicine, University of California, Irvine, CA 92697, United States of America; Department of Environmental and Occupational Health, University of California, Irvine, CA 92697, United States of America
| | - Veedamali S Subramanian
- Department of Medicine, University of California, Irvine, CA 92697, United States of America.
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Zhao S, Che F, Yang L, Zheng Y, Wang D, Yang Y, Wang Y. First report of paternal uniparental disomy of chromosome 8 with SLC52A2 mutation in Brown-vialetto-van laere syndrome type 2 and an analysis of genotype-phenotype correlations. Front Genet 2022; 13:977914. [PMID: 36186484 PMCID: PMC9520306 DOI: 10.3389/fgene.2022.977914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 08/23/2022] [Indexed: 11/17/2022] Open
Abstract
Purpose: This study reports the clinical and genetic features of Brown-Vialetto-Van Laere syndrome (BVVL) type 2 in a case of uniparental disomy of chromosome 8 in mainland China and analyzes the genotype-phenotype correlation through a review of the literature of BVVL type 2 cases. Methods: The clinical characteristics, treatment, and follow-up data of the patient were summarized, and the etiology was identified by whole-exome sequencing and gene chip analysis. Correlations between the genotype and phenotype were analyzed by collecting clinical and genetic data of published cases and our patient. Results: We identified a homozygous mutation in SLC52A2 (NM_001253815.2 c.1255G>A) by trio-WES. Sanger sequencing confirmed that his father was heterozygous and his mother was wild type. Subsequently, paternal uniparental disomy of chromosome 8 [UPD (8)pat] was confirmed by chromosomal microarray analysis.The patient received long-term oral riboflavin treatment (7 mg/kg.d) and was followed up for 40 months by which time the child’s bulbar palsy, ataxia, and motor function had improved. A review of the literature and statistical analysis found that the symptoms of BVVL type 2 appear at the earliest shortly after birth and at the latest at 10 years of age. The median age of onset was 2.5 years, but the overall delay in diagnosis was a median of 5.6 years. The most common symptoms were hearing loss (83.9%), followed by muscle weakness (80.6%), visual impairment (64.5%), and ataxia (61.3%). To date, a total of 32 mutations in the SLC52A2 gene have been reported, with the most common being a missense mutation. Mutations occur throughout the length of the gene apart from at the N-terminus. In patients with missense mutations, homozygous pattern was more likely to present with ataxia as the first symptom (p < 0.05), while compound heterozygous pattern was more likely to develop respiratory insufficiency during the course of disease (p < 0.001). Moreover, patients with one missense mutation located in inside the transmembrane domain were more likely to have respiratory insufficiency than those with mutations both inside and outside the domain (p < 0.05). Riboflavin supplementation was an important factor in determining prognosis (p < 0.001). Conclusion: We report the first UPD(8)pat with SLC52A2 homozygous pathogenic mutation case in BVVL type 2, which expand the mutation spectrum of gene.
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Affiliation(s)
- Siyu Zhao
- Department of Pediatric neurology, Xi’an Children’s hospital, Xi’an, China
| | - Fengyu Che
- Shaanxi Institute of Pediatric Diseases, Xi’an Children’s Hospital, Xi’an, China
| | - Le Yang
- Department of Pediatric neurology, Xi’an Children’s hospital, Xi’an, China
| | - Yanyan Zheng
- Department of Pediatric neurology, Xi’an Children’s hospital, Xi’an, China
| | - Dong Wang
- Department of Pediatric neurology, Xi’an Children’s hospital, Xi’an, China
| | - Ying Yang
- Shaanxi Institute of Pediatric Diseases, Xi’an Children’s Hospital, Xi’an, China
- *Correspondence: Ying Yang, Yan Wang,
| | - Yan Wang
- Department of Pediatric neurology, Xi’an Children’s hospital, Xi’an, China
- *Correspondence: Ying Yang, Yan Wang,
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Subramanian VS, Teafatiller T, Vidal J, Gunaratne GS, Rodriguez-Ortiz CJ, Kitazawa M, Marchant JS. Calsyntenin-3 interacts with the sodium-dependent vitamin C transporter-2 to regulate vitamin C uptake. Int J Biol Macromol 2021; 192:1178-1184. [PMID: 34673103 PMCID: PMC9842108 DOI: 10.1016/j.ijbiomac.2021.10.058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 10/07/2021] [Accepted: 10/08/2021] [Indexed: 01/19/2023]
Abstract
Ascorbic acid (AA) uptake in neurons occurs via a Na+-dependent carrier-mediated process mediated by the sodium-dependent vitamin C transporter-2 (SVCT2). Relatively little information is available concerning the network of interacting proteins that support human (h)SVCT2 trafficking and cell surface expression in neuronal cells. Here we identified the synaptogenic adhesion protein, calsyntenin-3 (CLSTN3) as an hSVCT2 interacting protein from yeast two-hybrid (Y2H) screening of a human adult brain cDNA library. This interaction was confirmed by co-immunoprecipitation, mammalian two-hybrid (M2H), and co-localization in human cell lines. Co-expression of hCLSTN3 with hSVCT2 in SH-SY5Y cells led to a marked increase in AA uptake. Reciprocally, siRNA targeting hCLSTN3 inhibited AA uptake. In the J20 mouse model of Alzheimer's disease (AD), mouse (m)SVCT2 and mCLSTN3 expression levels in hippocampus were decreased. Similarly, expression levels of hSVCT2 and hCLSTN3 were markedly decreased in hippocampal samples from AD patients. These findings establish CLSTN3 as a novel hSVCT2 interactor in neuronal cells with potential pathophysiological significance.
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Affiliation(s)
- Veedamali S. Subramanian
- Department of Medicine, University of California, Irvine, CA 92697, United States of America,Corresponding author. (V.S. Subramanian)
| | - Trevor Teafatiller
- Department of Medicine, University of California, Irvine, CA 92697, United States of America
| | - Janielle Vidal
- Department of Medicine, University of California, Irvine, CA 92697, United States of America,Department of Environmental and Occupational Health, University of California, Irvine, CA 92697, United States of America
| | - Gihan S. Gunaratne
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, United States of America
| | - Carlos J. Rodriguez-Ortiz
- Department of Medicine, University of California, Irvine, CA 92697, United States of America,Department of Environmental and Occupational Health, University of California, Irvine, CA 92697, United States of America
| | - Masashi Kitazawa
- Department of Medicine, University of California, Irvine, CA 92697, United States of America,Department of Environmental and Occupational Health, University of California, Irvine, CA 92697, United States of America
| | - Jonathan S. Marchant
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, United States of America
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Covarrubias-Pinto A, Acuña AI, Boncompain G, Papic E, Burgos PV, Perez F, Castro MA. Ascorbic acid increases SVCT2 localization at the plasma membrane by accelerating its trafficking from early secretory compartments and through the endocytic-recycling pathway. Free Radic Biol Med 2018; 120:181-191. [PMID: 29545069 DOI: 10.1016/j.freeradbiomed.2018.03.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/06/2018] [Accepted: 03/08/2018] [Indexed: 11/30/2022]
Abstract
Ascorbic acid (Asc) is an antioxidant molecule essential for physiological functions. The concentration of extracellular Asc increases during synaptic transmission and renal reabsorption. These phenomena induce an increase of the Sodium-dependent-Vitamin-C-transporter 2 (SVCT2) at plasma membrane (PM) localization, as we previously demonstrated in neuronal and non-neuronal cells. Hence, the aim of this study was to evaluate intracellular SVCT2 trafficking kinetics in response to Asc. We observed two peaks of SVCT2 localization and function at the PM (at 5-10 min, "acute response", and 30-60 min, "post-acute response") when cells were incubated with Asc. We defined that the post-acute response was dependent on SVCT2 located in early secretory compartments, and its trafficking was abolished with Tunicamycin and Brefeldin A treatment. Moreover, using the RUSH system to retain and synchronize cargo secretion through the secretory pathway we demonstrated that the post-acute response increases SVCT2 trafficking kinetics from the ER to the PM suggesting the retention of SVCT2 at the early secretory pathway when Asc is absent. However, these observations do not explain the increased SVCT2 levels at the PM during the "acute" response, suggesting the involvement of a faster mechanism in close proximity with the PM. To investigate the possible role of endosomal compartments, we tested the effect of endocytosis inhibition. Expression of dominant-negative (DN) versions of the GTPase-dynamin II and clathrin-accessory protein AP180 showed a significant increase in SVCT2 levels at the PM. Moreover, expression of Rab11-DN, a GTPase implicated in cargo protein recycling from endosomes to the PM showed a similar outcome, strongly indicating that Asc impacts SVCT2 trafficking during the acute response. Therefore, our results revealed two mechanisms by which Asc modulates SVCT2 levels at the PM, one at the early secretory pathway and another at the endocytic compartments. We propose that these two mechanisms have key protective implications in the homeostasis of metabolically active and specialized tissues.
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Affiliation(s)
- A Covarrubias-Pinto
- Biochemistry and Microbiology Institute, Faculty of Sciences, Universidad Austral de Chile, Valdivia, Chile; Center for Interdisciplinary Studies of the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
| | - A I Acuña
- Biochemistry and Microbiology Institute, Faculty of Sciences, Universidad Austral de Chile, Valdivia, Chile; Center for Interdisciplinary Studies of the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
| | - G Boncompain
- Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - E Papic
- Biochemistry and Microbiology Institute, Faculty of Sciences, Universidad Austral de Chile, Valdivia, Chile; Center for Interdisciplinary Studies of the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile
| | - P V Burgos
- Department of Physiology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile; Center for Interdisciplinary Studies of the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile; Center for Cell Biology and Biomedicine, School of Sciences and School of Medicine, Universidad San Sebastián, Santiago, Chile
| | - F Perez
- Institut Curie, PSL Research University, CNRS UMR144, Paris, France
| | - M A Castro
- Biochemistry and Microbiology Institute, Faculty of Sciences, Universidad Austral de Chile, Valdivia, Chile; Center for Interdisciplinary Studies of the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile; Research Initiative for Brain Rejuvenation (ReBrain), Chile.
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Wohlrab C, Phillips E, Dachs GU. Vitamin C Transporters in Cancer: Current Understanding and Gaps in Knowledge. Front Oncol 2017; 7:74. [PMID: 28484682 PMCID: PMC5402541 DOI: 10.3389/fonc.2017.00074] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 04/06/2017] [Indexed: 11/14/2022] Open
Abstract
Sufficient uptake and whole body distribution of vitamin C (ascorbate) is essential for many biochemical processes, including some that are vital for tumor growth and spread. Uptake of ascorbate into cancer cells is modulated by availability, tumor blood flow, tissue diffusion parameters, and ascorbate transport proteins. Uptake into cells is mediated by two families of transport proteins, namely, the solute carrier gene family 23, consisting of sodium-dependent vitamin C transporters (SVCTs) 1 and 2, and the SLC2 family of glucose transporters (GLUTs). GLUTs transport the oxidized form of the vitamin, dehydroascorbate (DHA), which is present at negligible to low physiological levels. SVCT1 and 2 are capable of accumulating ascorbate against a concentration gradient from micromolar concentrations outside to millimolar levels inside of cells. Investigating the expression and regulation of SVCTs in cancer has only recently started to be included in studies focused on the role of ascorbate in tumor formation, progression, and response to therapy. This review gives an overview of the current, limited knowledge of ascorbate transport across membranes, as well as tissue distribution, gene expression, and the relevance of SVCTs in cancer. As tumor ascorbate accumulation may play a role in the anticancer activity of high dose ascorbate treatment, further research into ascorbate transport in cancer tissue is vital.
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Affiliation(s)
- Christina Wohlrab
- Mackenzie Cancer Research Group, Department of Pathology, University of Otago, Christchurch, New Zealand
| | - Elisabeth Phillips
- Mackenzie Cancer Research Group, Department of Pathology, University of Otago, Christchurch, New Zealand
| | - Gabi U Dachs
- Mackenzie Cancer Research Group, Department of Pathology, University of Otago, Christchurch, New Zealand
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Subramanian VS, Kapadia R, Ghosal A, Said HM. Identification of residues/sequences in the human riboflavin transporter-2 that is important for function and cell biology. Nutr Metab (Lond) 2015; 12:13. [PMID: 25798182 PMCID: PMC4367879 DOI: 10.1186/s12986-015-0008-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 02/18/2015] [Indexed: 11/26/2022] Open
Abstract
Background Riboflavin (RF) is essential for normal cellular metabolic activities. Human cells obtain RF from their surroundings via a carrier-mediated process that involves RF transporters -1, -2 & -3 (hRFVT -1, -2 & -3; products of SLC52A1, -A2 and -A3 genes, respectively). Little is known about the structural features of these transporters that are important for their function/cell biology. Our aim in this study was to address these issues for the hRFVT-2, a transporter linked to the neurodegenerative disorder Brown-Vialetto-Van Laere Syndrome (BVVLS). Methods We used comparative protein-structure modelling to predict residues that interact with two amino acids known to be critical for hRFVT-2 function (the clinical mutants L123 and L339), site-directed mutagenesis, and truncation approach in the human-derived brain U87 cell model. Results First we showed that the defect in the function of the L123 and L339 hRFVT-2 clinical mutants is related to a reduction in protein stability/translation efficiency and to retention of the protein in the ER. Mutating V120 and L121 (residues predicted to interact with L123) and L342 (a residue predicted to interact with L339) also led to a significant inhibition in hRFVT-2 function (with no change in membrane expression); this inhibition was associated with changes in protein stability/translation efficiency (in the case of V120A and L342A) and an impairment in transport function (in the case of L121). Truncating the N- and C- terminals of hRFVT-2 led to significant inhibition in RF uptake, which was associated with changes in protein stability/translation efficiency (it was also associated with a partial impairment in membrane targeting in the case of the N-terminal truncation). Conclusion These investigations report on identification of residues/sequences in the hRFVT-2 protein that is important for its physiological function and cell biology.
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Affiliation(s)
- Veedamali S Subramanian
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, CA 92697 USA ; Department of Veterans Affairs Medical Center, Long Beach, CA 90822 USA
| | - Rubina Kapadia
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, CA 92697 USA ; Department of Veterans Affairs Medical Center, Long Beach, CA 90822 USA
| | - Abhisek Ghosal
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, CA 92697 USA ; Department of Veterans Affairs Medical Center, Long Beach, CA 90822 USA
| | - Hamid M Said
- Departments of Medicine, Physiology/Biophysics, University of California, Irvine, CA 92697 USA ; Department of Veterans Affairs Medical Center, Long Beach, CA 90822 USA
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Bürzle M, Suzuki Y, Ackermann D, Miyazaki H, Maeda N, Clémençon B, Burrier R, Hediger MA. The sodium-dependent ascorbic acid transporter family SLC23. Mol Aspects Med 2013; 34:436-54. [PMID: 23506882 DOI: 10.1016/j.mam.2012.12.002] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 11/16/2012] [Indexed: 12/31/2022]
Affiliation(s)
- Marc Bürzle
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
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Frillingos S. Insights to the evolution of Nucleobase-Ascorbate Transporters (NAT/NCS2 family) from the Cys-scanning analysis of xanthine permease XanQ. INTERNATIONAL JOURNAL OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2012; 3:250-272. [PMID: 23097742 PMCID: PMC3476789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 07/02/2012] [Indexed: 06/01/2023]
Abstract
The nucleobase-ascorbate transporter or nucleobase-cation symporter-2 (NAT/NCS2) family is one of the five known families of transporters that use nucleobases as their principal substrates and the only one that is evolutionarily conserved and widespread in all major taxa of organisms. The family is a typical paradigm of a group of related transporters for which conservation in sequence and overall structure correlates with high functional variations between homologs. Strikingly, the human homologs fail to recognize nucleobases or related cytotoxic compounds. This fact allows important biomedical perspectives for translation of structure-function knowledge on this family to the rational design of targeted antimicrobial purine-related drugs. To date, very few homologs have been characterized experimentally in detail and only two, the xanthine permease XanQ and the uric acid/xanthine permease UapA, have been studied extensively with site-directed mutagenesis. Recently, the high-resolution structure of a related homolog, the uracil permease UraA, has been solved for the first time with crystallography. In this review, I summarize current knowledge and emphasize how the systematic Cys-scanning mutagenesis of XanQ, in conjunction with existing biochemical and genetic evidence for UapA and the x-ray structure of UraA, allow insight on the structure-function and evolutionary relationships of this important group of transporters. The review is organized in three parts referring to (I) the theory of use of Cys-scanning approaches in the study of membrane transporter families, (II) the state of the art with experimental knowledge and current research on the NAT/NCS2 family, (III) the perspectives derived from the Cys-scanning analysis of XanQ.
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Affiliation(s)
- Stathis Frillingos
- Laboratory of Biological Chemistry, University of Ioannina Medical School 45110 Ioannina Greece
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Pecci A, Biino G, Fierro T, Bozzi V, Mezzasoma A, Noris P, Ramenghi U, Loffredo G, Fabris F, Momi S, Magrini U, Pirastu M, Savoia A, Balduini C, Gresele P. Alteration of liver enzymes is a feature of the MYH9-related disease syndrome. PLoS One 2012; 7:e35986. [PMID: 22558294 PMCID: PMC3338476 DOI: 10.1371/journal.pone.0035986] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 03/26/2012] [Indexed: 11/18/2022] Open
Abstract
Background MYH9-related disease (MYH9-RD) is a rare autosomal dominant genetic syndrome characterized by congenital thrombocytopenia associated with the risk of developing progressive nephropathy, sensorineural deafness, and presenile cataract. During the collection of a large case-series of patients with MYH9-RD we noticed several cases with unexplained elevation of liver enzymes. Our aim was to evaluate if the alteration of liver tests is a feature of the MYH9-RD and to define its clinical significance. Methods and Findings Data concerning liver tests, prospectively recorded in the Italian Registry for MYH9-RD, were collected and compared with those of three control populations: patients with autoimmune thrombocytopenia, patients with inherited thrombocytopenias other than MYH9-RD, and the participants to a large epidemiologic survey in an Italian geographic isolate. Thirty-eight of 75 evaluable MYH9-RD patients (50.7%) showed an elevation of ALT and/or AST, and 17 of 63 (27.0%) an increase of GGT. The increases ranged from 1.9±0.7 to 2.7±1.6 fold the upper normal limit. The prevalence of liver test alterations was significantly higher in MYH9-RD patients than in each of the control populations, with odds ratios ranging from 8.2 (95% CIs 2.2–44.8) to 24.7 (14.8–40.8). Clinical follow-up and more detailed liver studies of a subset of patients, including ultrasound liver scan, liver elastography and liver biopsy in one case, did not show any significant structural damage or evolution towards liver insufficiency. Conclusions Elevation of liver enzymes is a frequent and previously unrecognized feature of the MYH9-RD syndrome; however, this defect does not appear to have poor prognostic value.
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Affiliation(s)
- Alessandro Pecci
- Department of Internal Medicine, IRCCS Policlinico San Matteo Foundation and University of Pavia, Pavia, Italy
| | - Ginevra Biino
- Institute of Molecular Genetics, CNR, Pavia, Italy
- Institution of Population Genetics, CNR, Sassari, Italy
| | - Tiziana Fierro
- Division of Internal and Cardiovascular Medicine, Department of Internal Medicine, University of Perugia, Perugia, Italy
| | - Valeria Bozzi
- Department of Internal Medicine, IRCCS Policlinico San Matteo Foundation and University of Pavia, Pavia, Italy
| | - Annamaria Mezzasoma
- Division of Internal and Cardiovascular Medicine, Department of Internal Medicine, University of Perugia, Perugia, Italy
| | - Patrizia Noris
- Department of Internal Medicine, IRCCS Policlinico San Matteo Foundation and University of Pavia, Pavia, Italy
| | - Ugo Ramenghi
- Department of Pediatrics, University of Torino, Torino, Italy
| | - Giuseppe Loffredo
- Department of Oncology, Azienda “Santobono-Pausilipon", Pausilipon Hospital, Napoli, Italy
| | - Fabrizio Fabris
- Department of Medical Sciences, University of Padova, Padova, Italy
| | - Stefania Momi
- Division of Internal and Cardiovascular Medicine, Department of Internal Medicine, University of Perugia, Perugia, Italy
| | | | - Mario Pirastu
- Institution of Population Genetics, CNR, Sassari, Italy
| | - Anna Savoia
- Laboratory of Genetics, Institute for Maternal and Child Health – IRCCS “Burlo Garofolo", Trieste, Italy
| | - Carlo Balduini
- Department of Internal Medicine, IRCCS Policlinico San Matteo Foundation and University of Pavia, Pavia, Italy
| | - Paolo Gresele
- Division of Internal and Cardiovascular Medicine, Department of Internal Medicine, University of Perugia, Perugia, Italy
- * E-mail:
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Bürzle M, Hediger MA. Functional and Physiological Role of Vitamin C Transporters. CO-TRANSPORT SYSTEMS 2012. [DOI: 10.1016/b978-0-12-394316-3.00011-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Jiménez-Fernández E, Ponce M, Zuasti E, Fernández-Díaz C, Manchado M, Infante C. Molecular characterization and transcriptional regulation of the sodium-dependent vitamin C transporter genes (slc23a1 and slc23a2) in a teleost fish, the Senegalese sole (Solea senegalensis). Comp Biochem Physiol B Biochem Mol Biol 2011; 161:208-18. [PMID: 22142801 DOI: 10.1016/j.cbpb.2011.11.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 11/17/2011] [Accepted: 11/17/2011] [Indexed: 01/29/2023]
Abstract
Vitamin C (ascorbic acid, AA) is an antioxidant that acts as a free radical scavenger and cofactor for several important enzymatic reactions, thus being important for normal cellular functions, growth and development. Accumulation of AA in cells depends on two types of sodium-dependent vitamin C transporters (SVCTs), designed as SVCT1 and SVCT2. In human, they are the products of SLC23A1 and SLC23A2 genes, respectively. In the present work, the molecular cloning of the cDNAs corresponding to slc23a1 and slc23a2 in a teleost fish, the Senegalese sole (Solea senegalensis Kaup, 1858) is first described. Sequence analysis of the predicted polypeptides revealed a conserved topology with those of mammals with important motifs involved in structure and function, being also present in svct1 and svct2. Phylogenetic analyses including a range of vertebrate SVCTs suggest that both transporters are the result of an ancient gene duplication event that occurred prior to the divergence of tetrapods and teleosts, which took place 450 million years ago. Expression profiles in juvenile tissues and during larval development were analyzed using a real-time PCR approach. In juvenile fish, slc23a1 was strongly expressed in intestine, whereas slc23a2 exhibited a widespread distribution in tissues. Transcripts of both genes were detected at early developmental stages, probably representing mRNAs of maternal origin. A possible regulation by their own substrate was detected after first uptakes of AA from diet in both genes. During metamorphosis, both slc23a1 and slc23a2 were down-regulated, the former in a thyroid hormone (TH) dependent way. This pattern coincided with a significant reduction in the AA content of larvae during metamorphosis. These results are interpreted in a physiological context of general reduction in the metabolism of metamorphic larvae. Data presented here provide the first step toward a better understanding of the physiological role of SVCTs in teleost fish.
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