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Sadeq S, Chitcharoen S, Al-Hashimi S, Rattanaburi S, Casement J, Werner A. Significant Variations in Double-Stranded RNA Levels in Cultured Skin Cells. Cells 2024; 13:226. [PMID: 38334619 PMCID: PMC10854852 DOI: 10.3390/cells13030226] [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: 11/27/2023] [Revised: 01/18/2024] [Accepted: 01/22/2024] [Indexed: 02/10/2024] Open
Abstract
Endogenous double-stranded RNA has emerged as a potent stimulator of innate immunity. Under physiological conditions, endogenous dsRNA is maintained in the cell nucleus or the mitochondria; however, if protective mechanisms are breached, it leaches into the cytoplasm and triggers immune signaling pathways. Ectopic activation of innate immune pathways is associated with various diseases and senescence and can trigger apoptosis. Hereby, the level of cytoplasmic dsRNA is crucial. We have enriched dsRNA from two melanoma cell lines and primary dermal fibroblasts, including a competing probe, and analyzed the dsRNA transcriptome using RNA sequencing. There was a striking difference in read counts between the cell lines and the primary cells, and the effect was confirmed by northern blotting and immunocytochemistry. Both mitochondria (10-20%) and nuclear transcription (80-90%) contributed significantly to the dsRNA transcriptome. The mitochondrial contribution was lower in the cancer cells compared to fibroblasts. The expression of different transposable element families was comparable, suggesting a general up-regulation of transposable element expression rather than stimulation of a specific sub-family. Sequencing of the input control revealed minor differences in dsRNA processing pathways with an upregulation of oligoadenylate synthase and RNP125 that negatively regulates the dsRNA sensors RIG1 and MDA5. Moreover, RT-qPCR, Western blotting, and immunocytochemistry confirmed the relatively minor adaptations to the hugely different dsRNA levels. As a consequence, these transformed cell lines are potentially less tolerant to interventions that increase the formation of endogenous dsRNA.
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Affiliation(s)
- Shaymaa Sadeq
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; (S.S.); (S.A.-H.)
- Fallujah College of Medicine, University of Fallujah, Al-Fallujah 31002, Iraq
| | - Suwalak Chitcharoen
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand;
- Center of Excellence in Systems Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand;
| | - Surar Al-Hashimi
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; (S.S.); (S.A.-H.)
- College of Medicine, University of Misan, Al-Sader Teaching Hospital, Amarah 62001, Iraq
| | - Somruthai Rattanaburi
- Center of Excellence in Systems Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand;
| | - John Casement
- Bioinformatics Support Unit, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
| | - Andreas Werner
- Biosciences Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; (S.S.); (S.A.-H.)
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2
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Khan D, Ali SA. On the Novel Process of Pristine Microplastic Bio-fragmentation by Zebrafish (Danio rerio). ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2023; 84:299-306. [PMID: 36929014 PMCID: PMC10019436 DOI: 10.1007/s00244-023-00987-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/18/2023] [Accepted: 02/22/2023] [Indexed: 06/18/2023]
Abstract
Microplastics are highly persistent particles that deliberately contaminate our ecosystem. These small-sized particles can pass through filtering systems into the water bodies, affecting various forms of aquatic and terrestrial life. However, little is known about their fragmentation process within the organism's body. In previous studies, commercially available microplastics were used that are rarely found in the environment naturally, hence they cannot mimic the effects on our surroundings. Therefore, using the zebrafish, Danio rerio we have evaluated the process of bio-fragmentation of ingested pristine polyethene microplastics which are widely used in our daily life. We have also examined their faecal pellets through Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR). Our results show that zebrafish can potentially bio-fragment the pristine microplastic particles into nano-plastic within a short period of 24 h. Additionally, zebrafish cannot recognize the pristine microplastic particles and can ingest them as food. No mortality occurred during the experiment. Thus, we have identified a natural pathway of microplastic bio-fragmentation, introducing an emerging role of zebrafish in biogeochemical cycling and the fate of plastics.
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Affiliation(s)
- Darakhshan Khan
- Postgraduate Department of Biotechnology, Saifia College of Science, Bhopal, 462001, India
| | - Sharique A Ali
- Postgraduate Department of Biotechnology, Saifia College of Science, Bhopal, 462001, India.
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López Nadal A, Boekhorst J, Lute C, van den Berg F, Schorn MA, Bergen Eriksen T, Peggs D, McGurk C, Sipkema D, Kleerebezem M, Wiegertjes GF, Brugman S. Omics and imaging combinatorial approach reveals butyrate-induced inflammatory effects in the zebrafish gut. Anim Microbiome 2023; 5:15. [PMID: 36869372 PMCID: PMC9985269 DOI: 10.1186/s42523-023-00230-2] [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: 10/25/2022] [Accepted: 02/01/2023] [Indexed: 03/05/2023] Open
Abstract
BACKGROUND Prebiotic feed additives aim to improve gut health by influencing the microbiota and the gut barrier. Most studies on feed additives concentrate on one or two (monodisciplinary) outcome parameters, such as immunity, growth, microbiota or intestinal architecture. A combinatorial and comprehensive approach to disclose the complex and multifaceted effects of feed additives is needed to understand their underlying mechanisms before making health benefit claims. Here, we used juvenile zebrafish as a model species to study effects of feed additives by integrating gut microbiota composition data and host gut transcriptomics with high-throughput quantitative histological analysis. Zebrafish received either control, sodium butyrate or saponin-supplemented feed. Butyrate-derived components such as butyric acid or sodium butyrate have been widely used in animal feeds due to their immunostimulant properties, thereby supporting intestinal health. Soy saponin is an antinutritional factor from soybean meal that promotes inflammation due to its amphipathic nature. RESULTS We observed distinct microbial profiles associated with each diet, discovering that butyrate (and saponin to a lesser extent) affected gut microbial composition by reducing the degree of community-structure (co-occurrence network analysis) compared to controls. Analogously, butyrate and saponin supplementation impacted the transcription of numerous canonical pathways compared to control-fed fish. For example, both butyrate and saponin increased the expression of genes associated with immune response and inflammatory response, as well as oxidoreductase activity, compared to controls. Furthermore, butyrate decreased the expression of genes associated with histone modification, mitotic processes and G-coupled receptor activity. High-throughput quantitative histological analysis depicted an increase of eosinophils and rodlet cells in the gut tissue of fish receiving butyrate after one week of feeding and a depletion of mucus-producing cells after 3 weeks of feeding this diet. Combination of all datasets indicated that in juvenile zebrafish, butyrate supplementation increases the immune and the inflammatory response to a greater extent than the established inflammation-inducing anti-nutritional factor saponin. Such comprehensive analysis was supplemented by in vivo imaging of neutrophil and macrophage transgenic reporter zebrafish (mpeg1:mCherry/mpx:eGFPi114) larvae. Upon exposure to butyrate and saponin, these larvae displayed a dose-dependent increase of neutrophils and macrophages in the gut area. CONCLUSION The omics and imaging combinatorial approach provided an integrated evaluation of the effect of butyrate on fish gut health and unraveled inflammatory-like features not previously reported that question the usage of butyrate supplementation to enhance fish gut health under basal conditions. The zebrafish model, due to its unique advantages, provides researchers with an invaluable tool to investigate effects of feed components on fish gut health throughout life.
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Affiliation(s)
- Adrià López Nadal
- grid.4818.50000 0001 0791 5666Cell Biology and Immunology Group, Wageningen University and Research, Wageningen, The Netherlands ,grid.4818.50000 0001 0791 5666Aquaculture and Fisheries Group, Wageningen University and Research, Wageningen, The Netherlands ,grid.4818.50000 0001 0791 5666Host-Microbe Interactomics, Wageningen University and Research, De Elst 1, 6708 WD Wageningen, The Netherlands
| | - Jos Boekhorst
- grid.4818.50000 0001 0791 5666Host-Microbe Interactomics, Wageningen University and Research, De Elst 1, 6708 WD Wageningen, The Netherlands
| | - Carolien Lute
- grid.4818.50000 0001 0791 5666Cell Biology and Immunology Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Frank van den Berg
- grid.4818.50000 0001 0791 5666Aquaculture and Fisheries Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Michelle A. Schorn
- grid.4818.50000 0001 0791 5666Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | | | - David Peggs
- Skretting Aquaculture Innovation, Stavanger, Norway
| | | | - Detmer Sipkema
- grid.4818.50000 0001 0791 5666Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Michiel Kleerebezem
- grid.4818.50000 0001 0791 5666Host-Microbe Interactomics, Wageningen University and Research, De Elst 1, 6708 WD Wageningen, The Netherlands
| | - Geert F. Wiegertjes
- grid.4818.50000 0001 0791 5666Aquaculture and Fisheries Group, Wageningen University and Research, Wageningen, The Netherlands
| | - Sylvia Brugman
- Host-Microbe Interactomics, Wageningen University and Research, De Elst 1, 6708 WD, Wageningen, The Netherlands.
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Okamura Y, Kono T, Sakai M, Hikima JI. Evolutional perspective and functional characteristics of interleukin-17 in teleosts. FISH & SHELLFISH IMMUNOLOGY 2023; 132:108496. [PMID: 36526158 DOI: 10.1016/j.fsi.2022.108496] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/10/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
Interleukin (IL)-17 is a proinflammatory cytokine and plays essential roles in adaptive and innate immune responses against bacterial and fungal infections. Especially in mammalian mucosal tissues, it is well known that innate immune responses via IL-17A and IL-17F, such as the production of antimicrobial peptides, are very important for microbiota control. In contrast, interesting insights into the functions of IL-17 have recently been reported in several teleost species, although little research has been conducted on teleost IL-17. In the present review, we focused on current insights on teleost IL-17 and speculated on the different or consensus parts of teleost IL-17 signaling compared to that of mammals. This review focuses on the role of teleost IL-17 in intestinal immunity. We expect that this review will encourage a further understanding of the roles and importance of IL-17 signaling in teleosts.
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Affiliation(s)
- Yo Okamura
- Department of Immunology, School of Medicine, University of Washington, Seattle, WA, 98109, USA
| | - Tomoya Kono
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan
| | - Masahiro Sakai
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan
| | - Jun-Ichi Hikima
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan.
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Ribeiro Santos-Rasera J, Giovanini de Lima R, Santos Alves D, Teresa Rosim Monteiro R, Wallace Pereira de Carvalho H. X-ray spectrometry imaging and chemical speciation assisting to understand the toxic effects of copper oxide nanoparticles on zebrafish ( Danio rerio). Nanotoxicology 2022; 16:645-657. [PMID: 36260497 DOI: 10.1080/17435390.2022.2133646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Currently, copper nanoparticles are used in various sectors of industry, agriculture, and medicine. To understand the effects induced by these nanoparticles, it is necessary to assess the environmental risk and safely expand their use. In this study, we evaluated the toxicity of copper oxide (nCuO) nanoparticles in Danio rerio adults, their distribution/concentration, and chemical form after exposure. This last assessment had never been performed on copper-exposed zebrafish. Such evaluation was done through the characterization of nCuO, acute exposure tests and analysis of distribution and concentration by microstructure X-ray fluorescence spectroscopy (µ-XRF) and atomic absorption spectroscopy (GF-AAS). Synchrotron X-ray absorption spectroscopy (XAS) was performed to find out the chemical form of copper in hotspots. The results show that the toxicity values of fish exposed to nCuO were 2.4 mg L-1 (25 nm), 12.36 mg L-1 (40 nm), 149.03 mg L-1 (80 nm) and 0.62 mg L-1 (CuSO4, used as a positive control). The total copper found in the fish was in the order of mg kg-1 and it was not directly proportional to the exposure concentration; most of the copper was concentrated in the gastric system. However, despite the existence of copper hotspots, chemical transformation of CuO into other compounds was not detected.
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Affiliation(s)
- Joyce Ribeiro Santos-Rasera
- Laboratory of Nuclear Instrumentation (LIN), Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, Brazil
| | - Rafael Giovanini de Lima
- Laboratory of Nuclear Instrumentation (LIN), Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, Brazil
| | - Dejane Santos Alves
- Universidade Tecnológica Federal do Paraná, Campus Santa Helena, Prolongamento da Rua São Luis S/N, Santa Helena, Brazil
| | - Regina Teresa Rosim Monteiro
- Laboratory of Ecotoxicology, Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, Brazil
| | - Hudson Wallace Pereira de Carvalho
- Laboratory of Nuclear Instrumentation (LIN), Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba, Brazil
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Interdependent Transcription of a Natural Sense/Antisense Transcripts Pair (SLC34A1/PFN3). Noncoding RNA 2022; 8:ncrna8010019. [PMID: 35202092 PMCID: PMC8877773 DOI: 10.3390/ncrna8010019] [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: 12/14/2021] [Revised: 01/17/2022] [Accepted: 02/08/2022] [Indexed: 11/17/2022] Open
Abstract
Natural antisense transcripts (NATs) constitute a significant group of regulatory, long noncoding RNAs. They are prominently expressed in testis but are also detectable in other organs. NATs are transcribed at low levels and co-expressed with related protein coding sense transcripts. Nowadays NATs are generally considered as regulatory, long noncoding RNAs without closer focus on the inevitable interference between sense and antisense expression. This work describes a cellular system where sense and antisense transcription of a specific locus (SLC34A1/PFN3) is induced using epigenetic modifiers and CRISPR-Cas9. The renal cell lines HEK293 and HKC-8 do not express SLC34A1/PFN3 under normal culture conditions. Five-day exposure to dexamethasone significantly stimulates sense transcript (SLC34A1) levels and antisense (PFN3) minimally; the effect is only seen in HEK293 cells. Enhanced expression is paralleled by reduced sense promoter methylation and an increase in activating histone marks. Expression is further modulated by cassettes that stimulate the expression of sense or antisense transcript but disrupt protein coding potential. Constitutive expression of a 5′-truncated SLC34A1 transcript increases sense expression independent of dexamethasone induction but also stimulates antisense expression. Concordant expression is confirmed with the antisense knock-in that also enhances sense expression. The antisense effect acts on transcription in cis since transient transfection with sense or antisense constructs fails to stimulate the expression of the opposite transcript. These results suggest that bi-directional transcription of the SLC34A1/PFN3 locus has a stimulatory influence on the expression of the opposite transcript involving epigenetic changes of the promoters. In perspective of extensive, previous research into bi-directionally transcribed SLC34A loci, the findings underpin a hypothesis where NATs display different biological roles in soma and germ cells. Accordingly, we propose that in somatic cells, NATs act like lncRNAs–with the benefit of close proximity to a potential target gene. In germ cells, however, recent evidence suggests different biological roles for NATs that require RNA complementarity and double-stranded RNA formation.
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7
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Dai YS, Pei WL, Wang YY, Wang Z, Zhuo MQ. Topology, tissue distribution, and transcriptional level of SLC34s in response to Pi and pH in grass carp Ctenopharyngodon idella. FISH PHYSIOLOGY AND BIOCHEMISTRY 2021; 47:1383-1393. [PMID: 34282499 DOI: 10.1007/s10695-021-00981-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
In the present study, two new SLC34 family members, named slc34a1b and slc34a2a, were isolated and characterized from grass carp Ctenopharyngodon idella. Topology, tissue distribution, and transcriptional response to phosphorus (Pi) and pH were compared among three members of SLC34 family (slc34a1b, slc34a2a, and slc34a2b) in grass carp. The length of validated cDNAs of grass carp slc34a1b and slc34a2a was 1494 bp and 1902 bp, and these two cDNAs encoded 497 and 633 amino acid residues, respectively. The domain analysis showed that three SLC34 members of grass carp contain architecture similar to that in mammals. Moreover, the mRNA of three slc34s was widely expressed in nine tissues (heart, brain, intestine, kidney, liver, muscle, gill, spleen, and skin), but at various levels. Our results revealed that 6 mM and 9 mM Pi incubation significantly reduced the mRNA expression of three slc34s in both CIK and L8824 cell lines from grass carp. The expression of slc34a1b was decreased in the CIK cells, but not in the L8824 cells after 3 mM Pi incubation. In CIK cells, 3 mM Pi incubation downregulated the expression of slc34a1b and slc34a2a, but not slc34a2b. In addition, the expression of three slc34s was significantly reduced at acidic pH in the CIK cells. Taken together, we characterized three SLC34 family members, revealed their specific distribution among different tissues, and elucidated their transcriptional responses to Pi and pH in two cell lines from grass carp. Our findings provide an insight into the physiological function of three SLC34s in fish.
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Affiliation(s)
- Yong-Shuang Dai
- School of Animal Science and Nutritional Engineering, Wuhan Polytechnic University, Wuhan, 430070, China
| | - Wen-Li Pei
- School of Animal Science and Nutritional Engineering, Wuhan Polytechnic University, Wuhan, 430070, China
| | - Yuan-Yuan Wang
- School of Animal Science and Nutritional Engineering, Wuhan Polytechnic University, Wuhan, 430070, China
| | - Zhe Wang
- School of Animal Science and Nutritional Engineering, Wuhan Polytechnic University, Wuhan, 430070, China
| | - Mei-Qin Zhuo
- School of Animal Science and Nutritional Engineering, Wuhan Polytechnic University, Wuhan, 430070, China.
- Laboratory of Molecular Nutrition for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan, 430070, China.
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8
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Werner A, Clark JE, Samaranayake C, Casement J, Zinad HS, Sadeq S, Al-Hashimi S, Smith M, Kotaja N, Mattick JS. Widespread formation of double-stranded RNAs in testis. Genome Res 2021; 31:1174-1186. [PMID: 34158368 PMCID: PMC8256860 DOI: 10.1101/gr.265603.120] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 06/02/2021] [Indexed: 12/27/2022]
Abstract
The testis transcriptome is highly complex and includes RNAs that potentially hybridize to form double-stranded RNA (dsRNA). We isolated dsRNA using the monoclonal J2 antibody and deep-sequenced the enriched samples from testes of juvenile Dicer1 knockout mice, age-matched controls, and adult animals. Comparison of our data set with recently published data from mouse liver revealed that the dsRNA transcriptome in testis is markedly different from liver: In testis, dsRNA-forming transcripts derive from mRNAs including promoters and immediate downstream regions, whereas in somatic cells they originate more often from introns and intergenic transcription. The genes that generate dsRNA are significantly expressed in isolated male germ cells with particular enrichment in pachytene spermatocytes. dsRNA formation is lower on the sex (X and Y) chromosomes. The dsRNA transcriptome is significantly less complex in juvenile mice as compared to adult controls and, possibly as a consequence, the knockout of Dicer1 has only a minor effect on the total number of transcript peaks associated with dsRNA. The comparison between dsRNA-associated genes in testis and liver with a reported set of genes that produce endogenous siRNAs reveals a significant overlap in testis but not in liver. Testis dsRNAs also significantly associate with natural antisense genes-again, this feature is not observed in liver. These findings point to a testis-specific mechanism involving natural antisense transcripts and the formation of dsRNAs that feed into the RNA interference pathway, possibly to mitigate the mutagenic impacts of recombination and transposon mobilization.
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Affiliation(s)
- Andreas Werner
- Biosciences Institute, Medical School, Newcastle University, Newcastle, NE2 4HH, United Kingdom
| | - James E Clark
- Biosciences Institute, Medical School, Newcastle University, Newcastle, NE2 4HH, United Kingdom
| | - Calum Samaranayake
- Biosciences Institute, Medical School, Newcastle University, Newcastle, NE2 4HH, United Kingdom
| | - John Casement
- Bioinformatics Support Unit, Medical School, Newcastle University, Newcastle, NE2 4HH, United Kingdom
| | - Hany S Zinad
- Biosciences Institute, Medical School, Newcastle University, Newcastle, NE2 4HH, United Kingdom
| | - Shaymaa Sadeq
- Biosciences Institute, Medical School, Newcastle University, Newcastle, NE2 4HH, United Kingdom
- Fallujah College of Medicine, Al-Fallujah University, Al-Fallujah, 9Q4V+H3, Iraq
| | - Surar Al-Hashimi
- Biosciences Institute, Medical School, Newcastle University, Newcastle, NE2 4HH, United Kingdom
| | - Martin Smith
- CHU Sainte-Justine Research Centre, Montreal, QC H3T 1C5, Canada
- Department of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Montreal, Montreal, QC H3T 1C5, Canada
| | - Noora Kotaja
- Institute of Biomedicine, University of Turku, Turku, FIN-20520, Finland
| | - John S Mattick
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
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Reactive Oxygen Species-Dependent Innate Immune Mechanisms Control Methicillin-Resistant Staphylococcus aureus Virulence in the Drosophila Larval Model. mBio 2021; 12:e0027621. [PMID: 34126772 PMCID: PMC8262968 DOI: 10.1128/mbio.00276-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Antibiotic-resistant Staphylococcus aureus strains constitute a major public health concern worldwide and are responsible for both health care- and community-associated infections. Here, we establish a robust and easy-to-implement model of oral S. aureus infection using Drosophila melanogaster larvae that allowed us to follow the fate of S. aureus at the whole-organism level as well as the host immune responses. Our study demonstrates that S. aureus infection triggers H2O2 production by the host via the Duox enzyme, thereby promoting antimicrobial peptide production through activation of the Toll pathway. Staphylococcal catalase mediates H2O2 neutralization, which not only promotes S. aureus survival but also minimizes the host antimicrobial response, hence reducing bacterial clearance in vivo. We show that while catalase expression is regulated in vitro by the accessory gene regulatory system (Agr) and the general stress response regulator sigma B (SigB), it no longer depends on these two master regulators in vivo. Finally, we confirm the versatility of this model by demonstrating the colonization and host stimulation capabilities of S. aureus strains belonging to different sequence types (CC8 and CC5) as well as of two other bacterial pathogens, Salmonella enterica serovar Typhimurium and Shigella flexneri. Thus, the Drosophila larva can be a general model to follow in vivo the innate host immune responses triggered during infection by human pathogens.
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10
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Kang JS, Park JW. Silver Ion Release Accelerated in the Gastrovascular Cavity of Hydra vulgaris Increases the Toxicity of Silver Sulfide Nanoparticles. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2021; 40:1662-1672. [PMID: 33595126 DOI: 10.1002/etc.5017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/29/2020] [Accepted: 02/12/2021] [Indexed: 06/12/2023]
Abstract
Silver nanoparticles (Ag-NPs) streamed into aquatic environments are chemically transformed into various forms, and one of the predominant forms is silver sulfide NPs (Ag2 S-NPs). Because of the lower dissolution rate of silver ions (Ag+ ), the toxicity of Ag2 S-NPs could be lower than that of Ag-NPs. However, the toxicity of Ag2 S-NPs has been observed to be restored under oxidative or acidic conditions. In the present study, 4 aquatic organisms, Pseudokirchneriella subcapitata (algae), Daphnia magna (crustacean), Danio rerio (fish), and Hydra vulgaris (cnidarian), were exposed to Ag2 S-NPs transformed from Ag-NPs using Na2 S under anoxic conditions; and acute toxicity was evaluated. The acute toxicity of Ag2 S-NPs was rarely observed in algae, crustaceans, and fish, whereas it was significantly restored in cnidarians. Although the dissolution rate was low in the medium exposed to Ag2 S-NPs, high Ag+ was detected in H. vulgaris. To understand the mechanisms of Ag2 S-NP toxicity in cnidarians, transcriptional profiles of H. vulgaris exposed to Ag-NPs, Ag2 S-NPs, and AgNO3 were analyzed. As a result, most of the genes that were significantly changed in the Ag2 S-NPs group were also found to be significantly changed in the AgNO3 group, indicating that the toxicity of Ag2 S-NPs was caused by Ag+ dissolved by the acidic condition in the gastrovascular cavity of H. vulgaris. This finding is the first in an aquatic organism and suggests the need to reconsider the stability and safety of Ag2 S-NPs in the aquatic environment. Environ Toxicol Chem 2021;40:1662-1672. © 2021 SETAC.
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Affiliation(s)
- Jae Soon Kang
- Department of Anatomy and Convergence Medical Science, Institute of Health Science, Bio Anti-aging Medical Research Center, Gyeongsang National University Medical School, Jinju, Gyeongsangnam-do, South Korea
| | - June-Woo Park
- Environmental Risk Assessment Research Division, Korea Institute of Toxicology, Munsan-eup, Jinju, Gyeongsangnam-do, South Korea
- Human and Environmental Toxicology Program, Korea University of Science and Technology, Yuseong-gu, Daejeon, South Korea
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11
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Yokota S, Nakamura K, Kamata R. A comparative study of nickel nanoparticle and ionic nickel toxicities in zebrafish: histopathological changes and oxidative stress. J Toxicol Sci 2020; 44:737-751. [PMID: 31708531 DOI: 10.2131/jts.44.737] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Industry demand for nanomaterials is growing, but metal nanoparticle toxicity is not fully understood. For example, nickel nanoparticles (NiNPs) are used in electric capacitors, and their consumption is increasing, but there have been few reports of their toxicity and environmental effects. To elucidate the toxicological characteristics of NiNPs, we investigated their effects on the histopathology and oxidative states of zebrafish (Danio rerio) and compared the results with those of ionic nickel. Zebrafish exposed to four different concentrations of NiNPs or NiCl2 for 72 hr or 7 days were subjected to histopathological analysis, and tissue samples were subjected to analyses for oxidative stress and gene expression. High concentrations of both NiNPs and NiCl2 caused tissue damage in the gills, digestive tract, and liver. The damage was typically characterized by epithelial degeneration and necrosis in the gills, esophagus, and intestines, as well as by lipid loss and palisade pattern degradation in the liver. The damages to the gills, esophagus, and intestines were more severe after exposure to NiNPs, but exposure to NiCl2 led to more severe liver damage. Exposure to NiNPs increased lipid peroxidation in the skin but decreased it in the liver and intestines; exposure to NiCl2 increased lipid peroxidation in the intestines. Only exposure to NiCl2 changed antioxidative responses, enzymatic antioxidant activities, and metallothionein gene expression. These results indicate that NiNPs, which are highly adsorptive, cause severe damage to the epithelium by physical contact with the cell surface and production of reactive oxygen spices, whereas ionic nickel, which is absorptive, affects cellular antioxidative responses by absorption into the body and delivery to the liver.
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Affiliation(s)
- Shohei Yokota
- Laboratory of Toxicology, School of Veterinary Medicine, Kitasato University
| | - Kazuichi Nakamura
- Laboratory of Toxicology, School of Veterinary Medicine, Kitasato University
| | - Ryo Kamata
- Laboratory of Toxicology, School of Veterinary Medicine, Kitasato University
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12
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Cassar S, Adatto I, Freeman JL, Gamse JT, Iturria I, Lawrence C, Muriana A, Peterson RT, Van Cruchten S, Zon LI. Use of Zebrafish in Drug Discovery Toxicology. Chem Res Toxicol 2019; 33:95-118. [PMID: 31625720 DOI: 10.1021/acs.chemrestox.9b00335] [Citation(s) in RCA: 275] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Unpredicted human safety events in clinical trials for new drugs are costly in terms of human health and money. The drug discovery industry attempts to minimize those events with diligent preclinical safety testing. Current standard practices are good at preventing toxic compounds from being tested in the clinic; however, false negative preclinical toxicity results are still a reality. Continual improvement must be pursued in the preclinical realm. Higher-quality therapies can be brought forward with more information about potential toxicities and associated mechanisms. The zebrafish model is a bridge between in vitro assays and mammalian in vivo studies. This model is powerful in its breadth of application and tractability for research. In the past two decades, our understanding of disease biology and drug toxicity has grown significantly owing to thousands of studies on this tiny vertebrate. This Review summarizes challenges and strengths of the model, discusses the 3Rs value that it can deliver, highlights translatable and untranslatable biology, and brings together reports from recent studies with zebrafish focusing on new drug discovery toxicology.
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Affiliation(s)
- Steven Cassar
- Preclinical Safety , AbbVie , North Chicago , Illinois 60064 , United States
| | - Isaac Adatto
- Stem Cell and Regenerative Biology , Harvard University , Cambridge , Massachusetts 02138 , United States
| | - Jennifer L Freeman
- School of Health Sciences , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Joshua T Gamse
- Drug Safety Evaluation , Bristol-Myers Squibb , New Brunswick , New Jersey 08901 , United States
| | | | - Christian Lawrence
- Aquatic Resources Program , Boston Children's Hospital , Boston , Massachusetts 02115 , United States
| | | | - Randall T Peterson
- Pharmacology and Toxicology, College of Pharmacy , University of Utah , Salt Lake City , Utah 84112 , United States
| | | | - Leonard I Zon
- Stem Cell Program and Division of Hematology/Oncology, Children's Hospital and Dana Farber Cancer Institute, Howard Hughes Medical Institute, Harvard Medical School, Harvard Stem Cell Institute, Stem Cell and Regenerative Biology Department , Harvard University , Boston , Massachusetts 02138 , United States
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Mondal P, Shaw P, Bandyopadhyay A, Dey Bhowmik A, Chakraborty A, Sudarshan M, Chattopadhyay A. Mixture effect of arsenic and fluoride at environmentally relevant concentrations in zebrafish (Danio rerio) liver: Expression pattern of Nrf2 and related xenobiotic metabolizing enzymes. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 213:105219. [PMID: 31195325 DOI: 10.1016/j.aquatox.2019.06.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/02/2019] [Accepted: 06/02/2019] [Indexed: 06/09/2023]
Abstract
Nrf2 is a crucial transcription factor that regulates the expression of cytoprotective enzymes and controls cellular redox homeostasis. Both arsenic and fluoride are potent toxicants that are known to induce Nrf2. They are reported to coexist in many areas of the world leading to complex mixture effects in exposed organisms. The present study investigated the expression of Nrf2 and related xenobiotic metabolizing enzymes along with other stress markers such as histopathological alterations, catalase activity, reduced glutathione content and lipid peroxidation in zebrafish liver as a function of combined exposure to environmentally relevant concentrations of arsenic (37.87 μgL-1 or 5.05 × 10-7 M) and fluoride (6.8 mg L-1 or 3.57 × 10-4 M) for 60 days. The decrease in the total reduced glutathione level was evident in all treatment conditions. Hyperactivity of catalase along with conspicuous elevation in reactive oxygen species, malondialdehyde content and histo-architectural anomalies signified the presence of oxidative stress in the treatment groups. Nrf2 was seen to be induced at both transcriptional and translational levels in case of both individual and co-exposure. The same pattern was observed in case of its nuclear translocation also. From the results of qRT-PCR it was evident that at each time point co-exposure to arsenic and fluoride seemed to alter the gene expression of Cu/Zn Sod, Mn Sod, Gpx and Nqo1 just like their individual exposure but at a very low magnitude. In conclusion, this study demonstrates for the first time the differential expression and activity of Nrf2 and other stress response genes in the zebrafish liver following individual and combined exposure to arsenic and fluoride.
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Affiliation(s)
- Paritosh Mondal
- Department of Zoology, Visva-Bharati, Santiniketan, 731235, West Bengal, India
| | - Pallab Shaw
- Department of Zoology, Visva-Bharati, Santiniketan, 731235, West Bengal, India
| | | | - Arpan Dey Bhowmik
- Department of Zoology, Visva-Bharati, Santiniketan, 731235, West Bengal, India
| | - Anindita Chakraborty
- UGC-DAE Consortium for Scientific Research, Kolkata Centre, 3/LB-8, Bidhan Nagar, Kolkata, 700098, West Bengal, India
| | - Muthammal Sudarshan
- UGC-DAE Consortium for Scientific Research, Kolkata Centre, 3/LB-8, Bidhan Nagar, Kolkata, 700098, West Bengal, India
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14
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Kwon KC, Lamb A, Fox D, Porphy Jegathese SJ. An evaluation of microalgae as a recombinant protein oral delivery platform for fish using green fluorescent protein (GFP). FISH & SHELLFISH IMMUNOLOGY 2019; 87:414-420. [PMID: 30703550 DOI: 10.1016/j.fsi.2019.01.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/15/2019] [Accepted: 01/25/2019] [Indexed: 05/15/2023]
Abstract
Recombinant proteins produced by biological systems such as bacteria, yeasts, mammalian and insect cell cultures are widely used for clinical or industrial purposes. Most therapeutic protein drugs require purification, cold chain, and injection, which make them prohibitively expensive and hinders their widespread use. Here, we describe a new economical oral vaccination platform using algae and evaluated its potential for the delivery of recombinant drugs using GFP expressed in the chloroplast of algal cells. The transplastomic algae expressing recombinant GFPs were freeze-dried for long-term storage at ambient temperature and for easy handling in feeding. GFPs bioencapsulated by lyophilized Chlamydomonas reinhardtii were found intact without degradation for several months at ambient temperature. The expression level of GFP in the lyophilized algae was estimated at 0.47 μg/mg dry weight. The GFPs bioencapsulated and orally delivered to Danio rerio were immunostained and observed in the intestinal tissues using a confocal microscope. Furthermore, the uptaken GFPs in the intestine were detected in the blood using ELISA and the detected level was 5.4 ng of GFP/μl of serum. These results demonstrate that microalgae can be a viable protein production and oral delivery system to vaccinate fish. The results give greater justification to continue exploring the concept of microalgal-based oral vaccines. The potential of the technology would greatly benefit aquaculture farmers by providing them with affordable, environmentally sustainable, and user-friendly vaccines.
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Affiliation(s)
- Kwang-Chul Kwon
- MicroSynbiotiX Ltd, 11011 N Torrey Pines Rd Ste. #135, La Jolla, CA, 92037, USA.
| | - Antonio Lamb
- MicroSynbiotiX Ltd, 11011 N Torrey Pines Rd Ste. #135, La Jolla, CA, 92037, USA
| | - David Fox
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Simon Jegan Porphy Jegathese
- MicroSynbiotiX Ltd, University College, Cork, Food Science Building, Level 4, Lab 442, Microbiology Department, Cork, Republic of Ireland
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Verri T, Werner A. Type II Na +-phosphate Cotransporters and Phosphate Balance in Teleost Fish. Pflugers Arch 2018; 471:193-212. [PMID: 30542786 DOI: 10.1007/s00424-018-2239-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 11/15/2018] [Accepted: 11/18/2018] [Indexed: 12/27/2022]
Abstract
Teleost fish are excellent models to study the phylogeny of the slc34 gene family, Slc34-mediated phosphate (Pi) transport and how Slc34 transporters contribute Pi homeostasis. Fish need to accumulate Pi from the diet to sustain growth. Much alike in mammals, intestinal uptake in fish is partly a paracellular and partly a Slc34-mediated transcellular process. Acute regulation of Pi balance is achieved in the kidney via a combination of Slc34-mediated secretion and/or reabsorption. A great plasticity is observed in how various species perform and combine the different processes of secretion and reabsorption. A reason for this diversity is found in one or two whole genome duplication events followed by potential gene loss; consequently, teleosts exhibit distinctly different repertoires of Slc34 transporters. Moreover, due to habitats with vastly different salinity, teleosts face the challenge of either preserving water in a hyperosmotic environment (seawater) or excreting water in hypoosmotic freshwater. An additional challenge in understanding teleost Pi homeostasis are the genome duplication and retention events that diversified peptide hormones such as parathyroid hormone and stanniocalcin. Dietary Pi and non-coding RNAs also regulate the expression of piscine Slc34 transporters. The adaptive responses of teleost Slc34 transporters to e.g. Pi diets and vitamin D are informative in the context of comparative physiology, but also relevant in applied physiology and aquaculture. In fact, Pi is essential for teleost fish growth but it also exerts significant adverse consequences if over-supplied. Thus, investigating Slc34 transporters helps tuning the physiology of commercially valuable teleost fish in a confined environment.
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Affiliation(s)
- Tiziano Verri
- Laboratory of General Physiology, Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy.
| | - Andreas Werner
- Epithelial Research Group, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK.
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16
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Forster IC. The molecular mechanism of SLC34 proteins: insights from two decades of transport assays and structure-function studies. Pflugers Arch 2018; 471:15-42. [PMID: 30244375 DOI: 10.1007/s00424-018-2207-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/06/2018] [Accepted: 09/11/2018] [Indexed: 01/08/2023]
Abstract
The expression cloning some 25 years ago of the first member of SLC34 solute carrier family, the renal sodium-coupled inorganic phosphate cotransporter (NaPi-IIa) from rat and human tissue, heralded a new era of research into renal phosphate handling by focussing on the carrier proteins that mediate phosphate transport. The cloning of NaPi-IIa was followed by that of the intestinal NaPi-IIb and renal NaPi-IIc isoforms. These three proteins constitute the main secondary-active Na+-driven pathways for apical entry of inorganic phosphate (Pi) across renal and intestinal epithelial, as well as other epithelial-like organs. The key role these proteins play in mammalian Pi homeostasis was revealed in the intervening decades by numerous in vitro and animal studies, including the development of knockout animals for each gene and the detection of naturally occurring mutations that can lead to Pi-handling dysfunction in humans. In addition to characterising their physiological regulation, research has also focused on understanding the underlying transport mechanism and identifying structure-function relationships. Over the past two decades, this research effort has used real-time electrophysiological and fluorometric assays together with novel computational biology strategies to develop a detailed, but still incomplete, understanding of the transport mechanism of SLC34 proteins at the molecular level. This review will focus on how our present understanding of their molecular mechanism has evolved in this period by highlighting the key experimental findings.
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Affiliation(s)
- Ian C Forster
- Ion Channels and Human Diseases Laboratory, Florey Institute of Neuroscience and Mental Health, 30 Royal Parade, Parkville, VIC, 3052, Australia.
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17
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Lewis L, Kwong RWM. Zebrafish as a Model System for Investigating the Compensatory Regulation of Ionic Balance during Metabolic Acidosis. Int J Mol Sci 2018; 19:E1087. [PMID: 29621145 PMCID: PMC5979485 DOI: 10.3390/ijms19041087] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 03/25/2018] [Accepted: 04/02/2018] [Indexed: 12/16/2022] Open
Abstract
Zebrafish (Danio rerio) have become an important model for integrative physiological research. Zebrafish inhabit a hypo-osmotic environment; to maintain ionic and acid-base homeostasis, they must actively take up ions and secrete acid to the water. The gills in the adult and the skin at larval stage are the primary sites of ionic regulation in zebrafish. The uptake of ions in zebrafish is mediated by specific ion transporting cells termed ionocytes. Similarly, in mammals, ion reabsorption and acid excretion occur in specific cell types in the terminal region of the renal tubules (distal convoluted tubule and collecting duct). Previous studies have suggested that functional regulation of several ion transporters/channels in the zebrafish ionocytes resembles that in the mammalian renal cells. Additionally, several mechanisms involved in regulating the epithelial ion transport during metabolic acidosis are found to be similar between zebrafish and mammals. In this article, we systemically review the similarities and differences in ionic regulation between zebrafish and mammals during metabolic acidosis. We summarize the available information on the regulation of epithelial ion transporters during acidosis, with a focus on epithelial Na⁺, Cl- and Ca2+ transporters in zebrafish ionocytes and mammalian renal cells. We also discuss the neuroendocrine responses to acid exposure, and their potential role in ionic compensation. Finally, we identify several knowledge gaps that would benefit from further study.
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Affiliation(s)
- Lletta Lewis
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada.
| | - Raymond W M Kwong
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada.
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18
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Innovative Disease Model: Zebrafish as an In Vivo Platform for Intestinal Disorder and Tumors. Biomedicines 2017; 5:biomedicines5040058. [PMID: 28961226 PMCID: PMC5744082 DOI: 10.3390/biomedicines5040058] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 09/26/2017] [Accepted: 09/29/2017] [Indexed: 12/12/2022] Open
Abstract
Colorectal cancer (CRC) is one of the world’s most common cancers and is the second leading cause of cancer deaths, causing more than 50,000 estimated deaths each year. Several risk factors are highly associated with CRC, including being overweight, eating a diet high in red meat and over-processed meat, having a history of inflammatory bowel disease, and smoking. Previous zebrafish studies have demonstrated that multiple oncogenes and tumor suppressor genes can be regulated through genetic or epigenetic alterations. Zebrafish research has also revealed that the activation of carcinogenesis-associated signal pathways plays an important role in CRC. The biology of cancer, intestinal disorders caused by carcinogens, and the morphological patterns of tumors have been found to be highly similar between zebrafish and humans. Therefore, the zebrafish has become an important animal model for translational medical research. Several zebrafish models have been developed to elucidate the characteristics of gastrointestinal diseases. This review article focuses on zebrafish models that have been used to study human intestinal disorders and tumors, including models involving mutant and transgenic fish. We also report on xenograft models and chemically-induced enterocolitis. This review demonstrates that excellent zebrafish models can provide novel insights into the pathogenesis of gastrointestinal diseases and help facilitate the evaluation of novel anti-tumor drugs.
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19
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Piatek MJ, Henderson V, Fearn A, Chaudhry B, Werner A. Ectopically expressed Slc34a2a sense-antisense transcripts cause a cerebellar phenotype in zebrafish embryos depending on RNA complementarity and Dicer. PLoS One 2017; 12:e0178219. [PMID: 28542524 PMCID: PMC5436864 DOI: 10.1371/journal.pone.0178219] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 05/09/2017] [Indexed: 02/06/2023] Open
Abstract
Natural antisense transcripts (NATs) are complementary to protein coding genes and potentially regulate their expression. Despite widespread occurrence of NATs in the genomes of higher eukaryotes, their biological role and mechanism of action is poorly understood. Zebrafish embryos offer a unique model system to study sense-antisense transcript interplay at whole organism level. Here, we investigate putative antisense transcript-mediated mechanisms by ectopically co-expressing the complementary transcripts during early zebrafish development. In zebrafish the gene Slc34a2a (Na-phosphate transporter) is bi-directionally transcribed, the NAT predominantly during early development up to 48 hours after fertilization. Declining levels of the NAT, Slc34a2a(as), coincide with an increase of the sense transcript. At that time, sense and antisense transcripts co-localize in the endoderm at near equal amounts. Ectopic expression of the sense transcript during embryogenesis leads to specific failure to develop a cerebellum. The defect is RNA-mediated and dependent on sense-antisense complementarity. Overexpression of a Slc34a2a paralogue (Slc34a2b) or the NAT itself had no phenotypic consequences. Knockdown of Dicer rescued the brain defect suggesting that RNA interference is required to mediate the phenotype. Our results corroborate previous reports of Slc34a2a-related endo-siRNAs in two days old zebrafish embryos and emphasize the importance of coordinated expression of sense-antisense transcripts. Our findings suggest that RNAi is involved in gene regulation by certain natural antisense RNAs.
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Affiliation(s)
- Monica J. Piatek
- RNA Interest Group, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Victoria Henderson
- RNA Interest Group, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Amy Fearn
- RNA Interest Group, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Bill Chaudhry
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Andreas Werner
- RNA Interest Group, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
- * E-mail:
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20
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Chen P, Huang Y, Bayir A, Wang C. Characterization of the isoforms of type IIb sodium-dependent phosphate cotransporter (Slc34a2) in yellow catfish, Pelteobagrus fulvidraco, and their vitamin D 3-regulated expression under low-phosphate conditions. FISH PHYSIOLOGY AND BIOCHEMISTRY 2017; 43:229-244. [PMID: 27620186 DOI: 10.1007/s10695-016-0282-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 08/27/2016] [Indexed: 06/06/2023]
Abstract
In this study, two isoforms slc34a2 genes (type IIb sodium-dependent phosphate cotransporter), slc34a2a2 and slc34a2b, were cloned from intestine and kidney of yellow catfish (Pelteobagrus fulvidraco), with rapid amplification of cDNA ends. The structure differences and the regulation effects of dietary VD3 under low phosphorus were compared among three isoforms of slc34a2 in yellow catfish. The predicted Slc34a2a2 and Slc34a2b proteins match 65 % and 53.8 % sequence identity, with Slc34a2a1, respectively. The membrane-spanning domains were different among these three isoforms. Intestinal Slc34a2a1 and Slc34a2a2 proteins had eight and eleven transmembrane domains, while renal Slc34a2b protein had nine. The tissue distribution study showed that same as slc34a2a1, slc34a2a2 mRNA was mainly distributed in intestine and slc34a2b mRNA in kidney. The effect of vitamin D3 (VD3) level on slc34a2 subfamily expression under low-phosphate conditions, induced by the addition of 0 (VD0), 324 (VD1), 1243 (VD2), 3621 (VD3), 8040 (VD4), or 22700 (VD5) IU VD3/kg feed, was assessed by qPCR. The dose-responsive expression of intestinal slc34a2a2 and high expression of intestinal slc34a2a2 in VD5 together with peak expression of kidney slc34a2b in VD3 coincided with the accumulation of body phosphate content. These data suggested that appropriate level of dietary VD3 up-regulated slc34a2a1, slc34a2a2, and slc34a2b mRNA levels, which increased phosphate retention. In conclusion, the current study provided another possible approach to improve dietary phosphate utilization by adding appropriate level of VD3 to a low-phosphate diet to regulate intestinal and renal slc34a2 gene expression and thus minimize the excretion of phosphorus in yellow catfish.
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Affiliation(s)
- Pei Chen
- The College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, 430070, People's Republic of China
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, People's Republic of China
| | - Yanqing Huang
- East China Sea Fisheries Research Institute, Chinese Academy of Fishery Science, Shanghai, 200090, People's Republic of China
| | - Abdulkadir Bayir
- Department of Aquaculture, Faculty of Fisheries, Atatürk University, 25240, Erzurum, Turkey
| | - Chunfang Wang
- The College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
- Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, 430070, People's Republic of China.
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, People's Republic of China.
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21
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Di- and tripeptide transport in vertebrates: the contribution of teleost fish models. J Comp Physiol B 2016; 187:395-462. [PMID: 27803975 DOI: 10.1007/s00360-016-1044-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/12/2016] [Accepted: 10/20/2016] [Indexed: 02/06/2023]
Abstract
Solute Carrier 15 (SLC15) family, alias H+-coupled oligopeptide cotransporter family, is a group of membrane transporters known for their role in the cellular uptake of di- and tripeptides (di/tripeptides) and peptide-like molecules. Of its members, SLC15A1 (PEPT1) chiefly mediates intestinal absorption of luminal di/tripeptides from dietary protein digestion, while SLC15A2 (PEPT2) mainly allows renal tubular reabsorption of di/tripeptides from ultrafiltration, SLC15A3 (PHT2) and SLC15A4 (PHT1) possibly interact with di/tripeptides and histidine in certain immune cells, and SLC15A5 has unknown function. Our understanding of this family in vertebrates has steadily increased, also due to the surge of genomic-to-functional information from 'non-conventional' animal models, livestock, poultry, and aquaculture fish species. Here, we review the literature on the SLC15 transporters in teleost fish with emphasis on SLC15A1 (PEPT1), one of the solute carriers better studied amongst teleost fish because of its relevance in animal nutrition. We report on the operativity of the transporter, the molecular diversity, and multiplicity of structural-functional solutions of the teleost fish orthologs with respect to higher vertebrates, its relevance at the intersection of the alimentary and osmoregulative functions of the gut, its response under various physiological states and dietary solicitations, and its possible involvement in examples of total body plasticity, such as growth and compensatory growth. By a comparative approach, we also review the few studies in teleost fish on SLC15A2 (PEPT2), SLC15A4 (PHT1), and SLC15A3 (PHT2). By representing the contribution of teleost fish to the knowledge of the physiology of di/tripeptide transport and transporters, we aim to fill the gap between higher and lower vertebrates.
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22
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Brugman S. The zebrafish as a model to study intestinal inflammation. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 64:82-92. [PMID: 26902932 DOI: 10.1016/j.dci.2016.02.020] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 02/16/2016] [Accepted: 02/17/2016] [Indexed: 06/05/2023]
Abstract
Starting out as a model for developmental biology, during the last decade, zebrafish have also gained the attention of the immunologists and oncologists. Due to its small size, high fecundity and full annotation of its genome, the zebrafish is an attractive model system. The fact that fish are transparent early in life combined with the growing list of immune cell reporter fish, enables in vivo tracking of immune responses in a complete organism. Since zebrafish develop ex utero from a fertilized egg, immune development can be monitored from the start of life. Given that several gut functions and immune genes are conserved between zebrafish and mammals, the zebrafish is an interesting model organism to investigate fundamental processes underlying intestinal inflammation and injury. This review will first provide some background on zebrafish intestinal development, bacterial colonization and immunity, showing the similarities and differences compared to mammals. This will be followed by an overview of the existing models for intestinal disease, and concluded by future perspectives in light of the newest technologies and insights.
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Affiliation(s)
- Sylvia Brugman
- Animal Sciences Group, Cell Biology and Immunology, Wageningen University, De Elst 1, room Ee1253, 6708 WD Wageningen, Netherlands.
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23
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Werner A, Patti M, Zinad HS, Fearn A, Laude A, Forster I. Molecular determinants of transport function in zebrafish Slc34a Na-phosphate transporters. Am J Physiol Regul Integr Comp Physiol 2016; 311:R1213-R1222. [PMID: 27784684 DOI: 10.1152/ajpregu.00020.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 10/14/2016] [Accepted: 10/14/2016] [Indexed: 11/22/2022]
Abstract
The epithelial Na+-coupled phosphate cotransporter family Slc34a (NaPi-II) is well conserved in vertebrates and plays an essential role in maintaining whole body levels of inorganic phosphate (Pi). A three-dimensional model of the transport protein has recently been proposed with defined substrate coordination sites. Zebrafish express two NaPi-II isoforms with high sequence identity but a 10-fold different apparent Km for Pi ([Formula: see text]). We took advantage of the two zebrafish isoforms to investigate the contribution of specific amino acids to Pi coordination and transport. Mutations were introduced to gradually transform the low-affinity isoform into a high-affinity transporter. The constructs were expressed in Xenopus laevis oocytes and functionally characterized. Becaue the cotransport of Pi and Na involves multiple steps that could all influence [Formula: see text], we performed a detailed functional analysis to characterize the impact of the mutations on particular steps of the transport cycle. We used varying concentrations of the substrates Pi and its slightly larger analog, arsenate, as well as the cosubstrate, Na+ Moreover, electrogenic kinetics were performed to assess intramolecular movements of the transporter. All of the mutations were found to affect multiple transport steps, which suggested that the altered amino acids induced subtle structural changes rather than coordinating Pi directly. The likely positions of the critical residues were mapped to the model of human Slc34a, and their localization in relation to the proposed substrate binding pockets concurs well with the observed functional data.
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Affiliation(s)
- Andreas Werner
- Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom;
| | - Monica Patti
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland; and
| | - Hany S Zinad
- Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Amy Fearn
- Institute for Cell and Molecular Biosciences, Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Alex Laude
- Bio-Imaging Unit, Medical School, University of Newcastle upon Tyne, United Kingdom
| | - Ian Forster
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, Zürich, Switzerland; and
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24
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Piatek MJ, Henderson V, Zynad HS, Werner A. Natural antisense transcription from a comparative perspective. Genomics 2016; 108:56-63. [PMID: 27241791 PMCID: PMC4996343 DOI: 10.1016/j.ygeno.2016.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 05/08/2016] [Accepted: 05/25/2016] [Indexed: 12/28/2022]
Abstract
Natural antisense transcripts (NATs) can interfere with the expression of complementary sense transcripts with exquisite specificity. We have previously cloned NATs of Slc34a loci (encoding Na-phosphate transporters) from fish and mouse. Here we report the cloning of a human SLC34A1-related NAT that represents an alternatively spliced PFN3 transcript (Profilin3). The transcript is predominantly expressed in testis. Phylogenetic comparison suggests two distinct mechanisms producing Slc34a-related NATs: Alternative splicing of a transcript from a protein coding downstream gene (Pfn3, human/mouse) and transcription from the bi-directional promoter (Rbpja, zebrafish). Expression analysis suggested independent regulation of the complementary Slc34a mRNAs. Analysis of randomly selected bi-directionally transcribed human/mouse loci revealed limited phylogenetic conservation and independent regulation of NATs. They were reduced on X chromosomes and clustered in regions that escape inactivation. Locus structure and expression pattern suggest a NATs-associated regulatory mechanisms in testis unrelated to the physiological role of the sense transcript encoded protein.
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Affiliation(s)
- Monica J Piatek
- RNA Interest Group, Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Victoria Henderson
- RNA Interest Group, Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Hany S Zynad
- RNA Interest Group, Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Andreas Werner
- RNA Interest Group, Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, United Kingdom.
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25
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Chen P, Tang Q, Wang C. Characterizing and evaluating the expression of the type IIb sodium-dependent phosphate cotransporter (slc34a2) gene and its potential influence on phosphorus utilization efficiency in yellow catfish (Pelteobagrus fulvidraco). FISH PHYSIOLOGY AND BIOCHEMISTRY 2016; 42:51-64. [PMID: 26298316 DOI: 10.1007/s10695-015-0116-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 08/17/2015] [Indexed: 06/04/2023]
Abstract
A sodium-dependent phosphate cotransporter gene, NaPi-IIb (slc34a2), was isolated from yellow catfish (Pelteobagrus fulvidraco) intestine through homology cloning and the rapid amplification of cDNA ends. The full-length cDNA of slc34a2 consisted of 2326 bp with an open reading frame encoding 621 amino acids, a 160-bp 5' untranslated region, and a 300-bp 3' untranslated region. The deduced amino acid sequence showed 79.0 and 70.9% sequence identity to Astyanax mexicanus and Pundamilia nyererei, respectively. The membrane-spanning domains based on the hydrophilic and hydrophobic properties of the deduced amino acids were predicted, and results showed that the putative protein had eight transmembrane domains, with the intracellular NH2 and COOH termini. Two functional regions including first intracellular loop and third extracellular loop as well as the six N-glycosylation sites in second extracellular loop were found. The slc34a2 mRNA in the tested tissues was examined through semiquantitative reverse transcription polymerase chain reaction and quantitative real-time PCR, with the highest level found in the anterior intestine, followed by the posterior and middle intestines. The slc34a2 mRNA expression in the whole intestine under different dietary phosphorus (P) treatments was detected using qPCR. The results showed that the slc34a2 expression levels in the low-P groups (0.33 and 0.56%) were significantly higher (p < 0.05) than levels in the sufficient-P (0.81%) and high-P (1.15, 1.31, and 1.57%) groups. High expression of slc34a2 mRNA in low-P groups stimulated P utilization efficiency, indicating the close relationship between genotype and phenotype in yellow catfish. In contrast with conventional strategies (formula and feeding strategies), this study provided another possible approach by using molecular techniques to increase the P utilization in yellow catfish.
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Affiliation(s)
- Pei Chen
- The College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
- Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, 430070, People's Republic of China
| | - Qin Tang
- The College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Chunfang Wang
- The College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
- Freshwater Aquaculture Collaborative Innovation Center of Hubei Province, Wuhan, 430070, People's Republic of China.
- Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, People's Republic of China.
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26
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Forster IC, Hernando N, Biber J, Murer H. Phosphate transport kinetics and structure-function relationships of SLC34 and SLC20 proteins. CURRENT TOPICS IN MEMBRANES 2012. [PMID: 23177991 DOI: 10.1016/b978-0-12-394316-3.00010-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Transport of inorganic phosphate (P(i)) is mediated by proteins belonging to two solute carrier families (SLC20 and SLC34). Members of both families transport P(i) using the electrochemical gradient for Na(+). The role of the SLC34 members as essential players in mammalian P(i) homeostasis is well established, whereas that of SLC20 proteins is less well defined. The SLC34 family comprises the following three isoforms that preferentially cotransport divalent P(i) and are expressed in epithelial tissue: the renal NaPi-IIa and NaPi-IIc are responsible for reabsorbing P(i) in the proximal tubule, whereas NaPi-IIb is more ubiquitously expressed, including the small intestine, where it mediates dietary P(i) absorption. The SLC20 family comprises two members (PiT-1, PiT-2) that preferentially cotransport monovalent P(i) and are expressed in epithelial as well as nonepithelial tissue. The transport kinetics of members of both families have been characterized in detail using heterologous expression in Xenopus oocytes. For the electrogenic NaPi-IIa/b, and PiT-1,-2, conventional electrophysiological techniques together with radiotracer methods have been applied, as well as time-resolved fluorometric measurements that allow new insights into local conformational changes of the protein during the cotransport cycle. For the electroneutral NaPi-IIc, conventional tracer uptake and fluorometry have been used to elucidate its transport properties. The 3-D structures of these proteins remain unresolved and structure-function studies have so far concentrated on defining the topology and identifying sites of functional importance.
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Affiliation(s)
- Ian C Forster
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, Winterthurerstrasse, Zurich, Switzerland.
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27
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Bucking C, Schulte PM. Environmental and nutritional regulation of expression and function of two peptide transporter (PepT1) isoforms in a euryhaline teleost. Comp Biochem Physiol A Mol Integr Physiol 2011; 161:379-87. [PMID: 22227314 DOI: 10.1016/j.cbpa.2011.12.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 12/13/2011] [Accepted: 12/17/2011] [Indexed: 12/17/2022]
Abstract
Expression and function of the oligopeptide transporter PepT1 in response to changes in environmental salinity have received little study despite the important role that dipeptides play in piscine nutrition. We cloned and sequenced two novel full-length cDNAs that encode Fundulus heteroclitus PepT1-type oligopeptide transporters, and examined their expression and functional properties in freshwater- and seawater-acclimated fish and in response to fasting and re-feeding. Phylogenetic analysis of vertebrate SLC15A1 sequences confirms the presence of two PepT1 isoforms, named SLC15A1a and SLC15A1b, in fish. Similar to other vertebrate SLC15A1s, these isoforms have 12 transmembrane domains, and amino acids essential for PepT1 function are conserved. Expression analysis revealed novel environment-specific expression of the SLC15A1 isoforms in F. heteroclitus, with only SLC15A1b expressed in seawater-acclimated fish, and both isoforms expressed in freshwater-acclimated fish. Fasting and re-feeding induced changes in the expression of SLC15A1a and SLC15A1b mRNA. Short-term fasting resulted in up-regulation of PepT1 mRNA levels, while prolonged fasting resulted in down-regulation. The resumption of feeding resulted in up-regulation of PepT1 above pre-fasted levels. Experiments using the in vitro gut sac technique suggest that the PepT1 isoforms differ in functional characteristics. An increased luminal pH resulted in decreased intestinal dipeptide transport in freshwater-acclimated fish but suggested an increased dipeptide transport in seawater-acclimated fish. Overall, this is the first evidence of multiple isoforms of PepT1 in fish whose expression is environmentally dependent and results in functional differences in intestinal dipeptide transport.
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Affiliation(s)
- Carol Bucking
- University of British Columbia, Department of Zoology, 6270 University Blvd, Vancouver, BC, Canada V6T 1Z4.
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28
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Beene LC, Halluer J, Yoshinaga M, Hamdi M, Liu Z. Pentavalent arsenate transport by zebrafish phosphate transporter NaPi-IIb1. Zebrafish 2011; 8:125-31. [PMID: 21854209 PMCID: PMC3174731 DOI: 10.1089/zeb.2011.0701] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Arsenate is a pentavalent form of arsenic that shares similar chemical properties to phosphate. It has been shown to be taken up by phosphate transporters in both eukaryotic and prokaryotic microbes such as yeast and Escherichia coli. Recently, the arsenate uptake in vertebrate cells was reported to be facilitated by mammalian type II sodium/phosphate transporter with different affinities. As arsenate is the most common form of arsenic exposure in aquatic system, identifying the uptake pathway of arsenate into aquatic animals is a crucial step in the elucidation of the entire metabolic pathway of arsenic. In this study, the ability of a zebrafish phosphate transporter, NaPi-IIb1 (SLC34a2a), to transport arsenate was examined. Our results demonstrate that a type II phosphate transporter in zebrafish, NaPi-IIb1, can transport arsenate in vitro when expressed in Xenopus laevis oocytes. NaPi-IIb1 mediates a high-affinity arsenate transport, with a K(m) of 0.22 mM. The natural substrate of NaPi-IIb1, dibasic phosphate, inhibits arsenate transport. Arsenate transport via NaPi-IIb1 is coupled with Na(+) and exhibits sigmoidal kinetics with a Hill coefficient of 3.24 ± 0.19. Consistent with these in vitro studies, significant arsenate accumulation is observed in all examined zebrafish tissues where NaPi-IIb1 is expressed, particularly intestine, kidney, and eye, indicating that zebrafish NaPi-IIb1 is likely the transport protein that is responsible for arsenic accumulation in vivo.
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Affiliation(s)
- Lauren C. Beene
- Department of Biological Sciences, Oakland University, Rochester, Michigan
| | - Janell Halluer
- Department of Biological Sciences, Oakland University, Rochester, Michigan
| | - Masafumi Yoshinaga
- Department of Cellular Biology and Pharmacology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida
| | - Mohammad Hamdi
- Department of Biological Sciences, Oakland University, Rochester, Michigan
| | - Zijuan Liu
- Department of Biological Sciences, Oakland University, Rochester, Michigan
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29
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Bakke AM, Glover C, Krogdahl Å. Feeding, digestion and absorption of nutrients. FISH PHYSIOLOGY 2010. [DOI: 10.1016/s1546-5098(10)03002-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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30
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Carlile M, Swan D, Jackson K, Preston-Fayers K, Ballester B, Flicek P, Werner A. Strand selective generation of endo-siRNAs from the Na/phosphate transporter gene Slc34a1 in murine tissues. Nucleic Acids Res 2009; 37:2274-82. [PMID: 19237395 PMCID: PMC2673434 DOI: 10.1093/nar/gkp088] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Natural antisense transcripts (NATs) are important regulators of gene expression. Recently, a link between antisense transcription and the formation of endo-siRNAs has emerged. We investigated the bi-directionally transcribed Na/phosphate cotransporter gene (Slc34a1) under the aspect of endo-siRNA processing. Mouse Slc34a1 produces an antisense transcript that represents an alternative splice product of the Pfn3 gene located downstream of Slc34a1. The antisense transcript is prominently found in testis and in kidney. Co-expression of in vitro synthesized sense/antisense transcripts in Xenopus oocytes indicated processing of the overlapping transcripts into endo-siRNAs in the nucleus. Truncation experiments revealed that an overlap of at least 29 base-pairs is required to induce processing. We detected endo-siRNAs in mouse tissues that co express Slc34a1 sense/antisense transcripts by northern blotting. The orientation of endo-siRNAs was tissue specific in mouse kidney and testis. In kidney where the Na/phosphate cotransporter fulfils its physiological function endo-siRNAs complementary to the NAT were detected, in testis both orientations were found. Considering the wide spread expression of NATs and the gene silencing potential of endo-siRNAs we hypothesized a genome-wide link between antisense transcription and monoallelic expression. Significant correlation between random imprinting and antisense transcription could indeed be established. Our findings suggest a novel, more general role for NATs in gene regulation.
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Affiliation(s)
- Mark Carlile
- Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle, UK
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31
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Carlile M, Nalbant P, Preston-Fayers K, McHaffie GS, Werner A. Processing of naturally occurring sense/antisense transcripts of the vertebrate Slc34a gene into short RNAs. Physiol Genomics 2008; 34:95-100. [PMID: 18413783 DOI: 10.1152/physiolgenomics.00004.2008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Overlapping sense/antisense RNAs transcribed in opposite directions from the same genomic locus are common in vertebrates. The impact of antisense transcription on gene regulation and cell biology is largely unknown. We show that sense/antisense RNAs of an evolutionarily conserved phosphate transporter gene (Slc34a2a) are coexpressed in a short time window during embryonic development of zebrafish at 48 hours postfertilization (hpf). To address the mechanism by which coexpressed sense/antisense transcripts are processed, we injected sense/antisense RNAs in various combinations into Xenopus oocytes. In the cytoplasm RNAs were stable in whatever combination expressed. In the nucleus coinjected sense/antisense transcripts were degraded into short RNAs of approximately 23 bases within 4 h. A homologous transcript from toad or another isoform (Slc34a2b) from zebrafish failed to trigger processing. In oocytes that were primed with nuclear sense/antisense RNA coinjections, a reporter RNA was rapidly degraded. We produced evidence that the observed processing of complementary transcripts was not restricted to Xenopus oocytes, because Slc34a-related short RNAs were detected in zebrafish embryos by Northern blotting. Signals were observed at stages that showed coexpression of sense/antisense transcripts. Remarkably, strand-specific probes revealed that the orientation of short RNAs was developmentally regulated. In addition, RNA from zebrafish embryos 48 hpf was able to induce degradation of reporter constructs in Xenopus oocytes. Our findings may give important clues to understanding the physiological role of the widespread antisense transcription.
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Affiliation(s)
- Mark Carlile
- RNA Biology Group, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
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32
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Forster IC, Virkki L, Bossi E, Murer H, Biber J. Electrogenic kinetics of a mammalian intestinal type IIb Na(+)/P(i) cotransporter. J Membr Biol 2007; 212:177-90. [PMID: 17342377 DOI: 10.1007/s00232-006-0016-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Revised: 06/08/2006] [Indexed: 10/23/2022]
Abstract
The kinetics of a type IIb Na(+)-coupled inorganic phosphate (Pi) cotransporter (NaPi-IIb) cloned from mouse small intestine were studied using the two-electrode voltage clamp applied to Xenopus oocytes. In the steady state, mouse NaPi-IIb showed a curvilinear I-V relationship, with rate-limiting behavior only for depolarizing potentials. The Pi dose dependence was Michaelian, with an apparent affinity constant for Pi (Km(pi)) of 10 +/- 1 microM: at -60 mV. Unlike for rat NaPi-IIa, (Km(pi)) increased with membrane hyperpolarization, as reported for human NaPi-IIa, flounder NaPi-IIb and zebrafish NaPi-IIb2. The apparent affinity constant for Na(+) (Km(na)) was 23 +/- 1 mM: at -60 mV, and the Na(+) activation was cooperative with a Hill coefficient of approximately 2. Pre-steady-state currents were documented in the absence of Pi and showed a strong dependence on external Na(+). The hyperpolarizing shift of the charge distribution midpoint potential was 65 mV/log[Na]. Approximately half the moveable charge was attributable to the empty carrier. A comparison of the voltage dependence of steady-state Pi-induced current and pre-steady-state charge movement indicated that for -120 mV <or= V <or= 0 mV the voltage dependence of the empty carrier was the main determinant of the curvilinear steady-state cotransport characteristic. External protons partially inhibited NaPi-IIb steady-state activity, independent of the titration of mono- and divalent Pi, and immobilized pre-steady-state charge movements associated with the first Na(+) binding step.
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Affiliation(s)
- Ian C Forster
- Institute of Physiology and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
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33
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Møbjerg N, Werner A, Hansen SM, Novak I. Physiological and molecular mechanisms of inorganic phosphate handling in the toad Bufo bufo. Pflugers Arch 2006; 454:101-13. [PMID: 17165072 DOI: 10.1007/s00424-006-0176-0] [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] [Received: 07/05/2006] [Accepted: 09/27/2006] [Indexed: 11/29/2022]
Abstract
The aim of this study was to elucidate mechanisms of P(i) handling in toads (Bufo bufo). We introduced toads to experimental solutions of various [P(i)] and high P(i) diets and measured urine and lymph [P(i)]. Both lymph and urine [P(i)] increased with increasing P(i) loads, indicating P(i) absorption across skin and intestine. An initial fragment of a NaPi-II type transporter was amplified from kidney, and the full-length sequence was obtained. The protein showed the molecular hallmarks of NaPi-IIb transporters. When expressed in Xenopus oocytes the clone showed unusual pH dependence, but apparent affinity constants for P(i) and Na(+) were in the range of other NaPi-II transporters. Expression profiling showed that the transporter was present in skin, intestine and kidney. Reverse transcription-polymerase chain reaction assays on dissected renal tubules indicated expression in the collecting duct system. Collecting tubules and ducts were isolated, perfused and microelectrode recordings showed electrogenic P(i) transport in apical and basolateral membranes. Taken together, our results show that P(i) is handled by intestine, kidney and skin. The presently cloned NaPi-IIb is a likely candidate involved in P(i) absorption across these epithelia. In addition, electrophysiological experiments suggest that the collecting duct system plays an important role in P(i) homeostasis.
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Affiliation(s)
- Nadja Møbjerg
- Institute of Molecular Biology, University of Copenhagen, August Krogh Building, Universitetsparken 13, 2100 Copenhagen, Denmark.
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34
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Bacconi A, Virkki LV, Biber J, Murer H, Forster IC. Renouncing electroneutrality is not free of charge: switching on electrogenicity in a Na+-coupled phosphate cotransporter. Proc Natl Acad Sci U S A 2005; 102:12606-11. [PMID: 16113079 PMCID: PMC1194947 DOI: 10.1073/pnas.0505882102] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Indexed: 11/18/2022] Open
Abstract
Renal type IIa Na+-coupled inorganic phosphate (Pi) cotransporters (NaPi-IIa) mediate divalent Pi transport in an electrogenic manner, whereas the renal type IIc isoform (NaPi-IIc) is electroneutral, yet it shows high sequence identity with NaPi-IIa. Dual uptake (32Pi/22Na) assays confirmed that NaPi-IIc displayed Na+-coupled Pi cotransport with a 2:1 (Na+:Pi) stoichiometry compared with 3:1 established for NaPi-IIa. This finding suggested that the electrogenicity of NaPi-IIa arises from the interaction of an additional Na+ ion compared with NaPi-IIc. To identify the molecular elements responsible for the functional difference between isoforms, we used chimera and amino acid replacement approaches. Transport activity of chimeras constructed with NaPi-IIa and NaPi-IIc indicated that residues within the first six transmembrane domains were essential for the electrogenicity of NaPi-IIa. Sequence comparison between electrogenic and electroneutral isoforms revealed differences in the charge and polarity of residues clustered in three areas, one of which included part of the predicted third transmembrane domain. Here, substitution of three residues with their NaPi-IIa equivalents in NaPi-IIc (S189A, S191A, and G195D) resulted in a transporter that displayed a 1:1 charge/Pi coupling, a 3:1 Na+:Pi stoichiometry, and transient currents that resembled pre-steady-state relaxations. The mutant's weaker voltage dependency and 10-fold lower apparent Pi affinity compared with NaPi-IIa indicated that other residues important for the NaPi-IIa kinetic fingerprint exist. Our findings demonstrate that, through a minimal number of side chain substitutions, we can effect a switch from electroneutral to electrogenic cotransporter function, concomitant with the appearance of a cosubstrate interaction site.
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Affiliation(s)
- Andrea Bacconi
- Institute of Physiology and Center for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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35
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Shmukler BE, Kurschat CE, Ackermann GE, Jiang L, Zhou Y, Barut B, Stuart-Tilley AK, Zhao J, Zon LI, Drummond IA, Vandorpe DH, Paw BH, Alper SL. Zebrafish slc4a2/ae2 anion exchanger: cDNA cloning, mapping, functional characterization, and localization. Am J Physiol Renal Physiol 2005; 289:F835-49. [PMID: 15914778 DOI: 10.1152/ajprenal.00122.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Although the zebrafish has been used increasingly for the study of pronephric kidney development, studies of renal ion transporters and channels of the zebrafish remain few. We report the cDNA cloning and characterization of the AE2 anion exchanger ortholog from zebrafish kidney, slc4a2/ae2. The ae2 gene in linkage group 2 encodes a polypeptide of 1,228 aa exhibiting 64% aa identity with mouse AE2a. The exon-intron boundaries of the zebrafish ae2 gene are nearly identical to those of the rodent and human genes. Whole-mount in situ hybridization detects ae2 mRNA in prospective midbrain as early as the five-somite stage, then later in the pronephric primordia and the forming pronephric duct, where it persists through 72 h postfertilization (hpf). Zebrafish Ae2 expressed in Xenopus laevis oocytes mediates Na(+)-independent, electroneutral (36)Cl(-)/Cl(-) exchange moderately sensitive to inhibition by DIDS, is inhibited by acidic intracellular pH and by acidic extracellular pH, but activated by (acidifying) ammonium and by hypertonicity. Zebrafish Ae2 also mediates Cl(-)/HCO(3)(-) exchange in X. laevis oocytes and accumulates in or near the plasma membrane in transfected HEK-293 cells. In 24-48 hpf zebrafish embryos, the predominant but not exclusive localization of Ae2 polypeptide is the apical membrane of pronephric duct epithelial cells. Thus Ae2 resembles its mammalian orthologs in function, mechanism, and acute regulation but differs in its preferentially apical expression in kidney. These results will inform tests of the role of Ae2 in zebrafish kidney development and function.
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Affiliation(s)
- Boris E Shmukler
- Molecular Medicine and Renal Units, Beth Israel Deaconess Med. Ctr. E/RW763, 330 Brookline Ave., Boston, MA 02215, USA
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36
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Sugiura SH, Ferraris RP. Contributions of different NaPi cotransporter isoforms to dietary regulation of P transport in the pyloric caeca and intestine of rainbow trout. ACTA ACUST UNITED AC 2004; 207:2055-64. [PMID: 15143139 DOI: 10.1242/jeb.00971] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The anatomical proximity and embryological relationship of the pyloric caeca (PC) and small intestine of rainbow trout has led to the frequent assumption, on little evidence, that they have the same enzymes and transporters. In trout, the PC is an important absorptive organ for dietary nutrients, but its role in dietary P absorption has not been reported. We found that apical inorganic phosphate (Pi) transport in PC comprises carrier-mediated and diffusive components. Carrier-mediated uptake was energy- and temperature-dependent, competitively inhibited and Na(+)-independent, and greater than the Na(+)-dependent intestinal uptake. Pi uptake in PC was pH-sensitive in the presence of Na(+). Despite the active Pi transport system in PC, high postprandial luminal Pi concentrations ( approximately 20 mmol l(-1)) indicate that diffusive uptake represents approximately 92% of total Pi uptake in PC of fed fish. The nucleotide sequence of a sodium-phosphate cotransporter (NaPi-II) isoform isolated from PC was approximately 8% different from the intestinal NaPi cotransporter. PC-NaPi mRNA was abundant in PC but rare in the intestine, whereas intestinal NaPi mRNA was abundant in the intestine but scarce in PC. Dietary P restriction reduced serum and bone P concentrations, increased intestine-type, but not PC-type, NaPi mRNA in PC, and increased Pi uptake in intestine but not in PC. Intestine-type NaPi expression may be useful for predicting dietary P deficiency.
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Affiliation(s)
- Shozo H Sugiura
- New Jersey Medical School, Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA
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37
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Verri T, Kottra G, Romano A, Tiso N, Peric M, Maffia M, Boll M, Argenton F, Daniel H, Storelli C. Molecular and functional characterisation of the zebrafish (Danio rerio) PEPT1-type peptide transporter. FEBS Lett 2003; 549:115-22. [PMID: 12914936 DOI: 10.1016/s0014-5793(03)00759-2] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We report the molecular and functional characterisation of a novel peptide transporter from zebrafish, orthologue to mammalian and avian PEPT1. Zebrafish PEPT1 is a low-affinity/high-capacity system. However, in contrast to higher vertebrate counterparts in which maximal transport activity is independent of extracellular pH, zebrafish PEPT1 maximal transport rates unexpectedly increase at alkaline extracellular pH. Zebrafish pept1 is highly expressed in the proximal intestine since day 4 post-fertilisation, thus preceding functional maturation of the gut, first feeding and complete yolk resorption. Zebrafish PEPT1 might help to understand the evolutionary and functional relationships among vertebrate peptide transporters. Moreover, zebrafish pept1 can be a useful marker for screening mutations that affect gut regionalisation, differentiation and morphogenesis.
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Affiliation(s)
- Tiziano Verri
- Department of Biological and Environmental Sciences and Technologies, University of Lecce, via Provinciale Lecce-Monteroni, I-73100 Lecce, Italy.
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38
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Graham C, Nalbant P, Schölermann B, Hentschel H, Kinne RKH, Werner A. Characterization of a type IIb sodium-phosphate cotransporter from zebrafish (Danio rerio) kidney. Am J Physiol Renal Physiol 2003; 284:F727-36. [PMID: 12488247 DOI: 10.1152/ajprenal.00356.2002] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Zebrafish (Danio rerio) express two isoforms of the type IIb Na-dependent P(i) cotransporter (NaPi). Type NaPi-IIb1 has previously been cloned and characterized. Here, we report the cloning of the NaPi-IIb2 transcript from zebrafish kidney, its localization, and its functional characterization. RT-PCR with renal RNA and degenerate NaPi-IIb-specific primers resulted in a specific fragment. 3'-Rapid amplification of cDNA ends yielded a product that contained typical NaPi-IIb characteristics such as a cysteine-rich COOH terminus and a PDZ (PSD95- Dlg-zona occludens-1) binding motif. Several approaches were unsuccessful at cloning the 5' end of the transcript; products lacked an in-frame start codon. The missing information was obtained from an EST (GenBank accession number ). The combined clone displayed a high degree of homology with published type IIb cotransporter sequences. Specific antibodies were raised against a COOH-terminal epitope of both NaPi-IIb1 and NaPi-IIb2 isoforms. Immunohistochemical mapping revealed apical expression of both isoforms in zebrafish renal and intestinal epithelia, as well as in bile ducts. The novel clone was expressed in oocytes, and function was assayed by the two-electrode voltage-clamp technique. The function of the new NaPi-IIb2 clone was found to be significantly different from NaPi-IIb1 despite strong structural similarities. NaPi-IIb2 was found to be strongly voltage sensitive, with higher affinities for both sodium and phosphate than NaPi-IIb1. Also, NaPi-IIb2 was significantly less sensitive to external pH than NaPi-IIb1. The strong structural similarity but divergent function makes these zebrafish transporters ideal models for the molecular mapping of functionally important regions in the type II NaPi-cotransporter family.
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Affiliation(s)
- C Graham
- School of Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne, NE2 4HH, United Kingdom
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39
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Kirschner U, Van Driessche W, Werner A, Wehner F. Hypertonic activation of phospholemman in solitary rat hepatocytes in primary culture. FEBS Lett 2003; 537:151-6. [PMID: 12606048 DOI: 10.1016/s0014-5793(03)00115-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Under hypertonic conditions, solitary rat hepatocytes in primary culture shrink and subsequently exhibit a distinct regulatory volume increase (RVI). Reverse-transcribed polymerase chain reaction and 5' and 3' RACE (rapid amplification of cDNA ends) techniques reveal that these cells express phospholemman (PLM). In whole-cell recordings, the hypertonic activation of a channel is observed that resembles PLM with respect to unitary conductance (600-700 pS), gating pattern, and non-selectivity for Na(+) over K(+). In Xenopus oocytes expressing hepatocyte PLM, hypertonic stress induces a non-selective cation conductance and noise analysis reveals the activation of a channel with a unitary conductance of approximately 700 pS. These results suggest a role of PLM in the RVI of rat hepatocytes.
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Affiliation(s)
- Udo Kirschner
- Max-Planck-Institut für molekulare Physiologie, Abteilung Epithelphysiologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
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Forster IC, Köhler K, Biber J, Murer H. Forging the link between structure and function of electrogenic cotransporters: the renal type IIa Na+/Pi cotransporter as a case study. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2002; 80:69-108. [PMID: 12379267 DOI: 10.1016/s0079-6107(02)00015-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Electrogenic cotransporters are membrane proteins that use the electrochemical gradient across the cell membrane of a cosubstrate ion, for example Na(+) or H(+), to mediate uphill cotransport of a substrate specific to the transport protein. The cotransport process involves recognition of both cosubstrate and substrate and translocation of each species according to a defined stoichiometry. Electrogenicity implies net movement of charges across the membrane in response to the transmembrane voltage and therefore, in addition to isotope flux assays, the cotransport kinetics can be studied in real-time using electrophysiological methods. As well as the cotransport mode, many cotransporters also display a uniport or slippage mode, whereby the cosubstrate ions translocate in the absence of substrate. The current challenge is to define structure-function relationships by identifying functionally important elements in the protein that confer the transport properties and thus contribute to the ultimate goal of having a 3-D model of the protein that conveys both structural and functional information. In this review we focus on a functional approach to meet this challenge, based on a combination of real-time electrophysiological assays, together with molecular biological and biochemical methods. This is illustrated, by way of example, using data obtained by heterologous expression of the renal Na(+)-coupled inorganic phosphate cotransporter (NaP(i)-IIa) for which structure-function relationships are beginning to emerge.
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Affiliation(s)
- Ian C Forster
- Physiologisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
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Lebens M, Lundquist P, Söderlund L, Todorovic M, Carlin NIA. The nptA gene of Vibrio cholerae encodes a functional sodium-dependent phosphate cotransporter homologous to the type II cotransporters of eukaryotes. J Bacteriol 2002; 184:4466-74. [PMID: 12142417 PMCID: PMC135239 DOI: 10.1128/jb.184.16.4466-4474.2002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nptA gene of Vibrio cholerae has significant protein sequence homology with type II sodium-dependent phosphate (P(i)) cotransporters found in animals but not previously identified in prokaryotes. The phylogeny of known type II cotransporter sequences indicates that nptA may be either an ancestral gene or a gene acquired from a higher eukaryotic source. The gene was cloned into an expression vector under the control of an inducible promoter and expressed in Escherichia coli. The results demonstrate that nptA encodes a functional protein with activity similar to that of the animal enzyme, catalyzing high-affinity, sodium-dependent P(i) uptake with comparable affinities for both sodium and phosphate ions. Furthermore, the activity of NptA is influenced by pH, again in a manner similar to that of the NaPi-2a subtype of the animal enzyme, although it lacks the corresponding REK motif thought to be responsible for this phenomenon. P(i) uptake activity, a component of which appeared to be sodium dependent, was increased in V. cholerae by phosphate starvation. However, it appears from the use of a reporter gene expressed from the nptA promoter that none of this activity is attributable to the induction of expression from nptA. It is thus proposed that the physiological function of NptA protein may be the rapid uptake of P(i) in preparation for rapid growth in nutrient-rich environments and that it may therefore play a role in establishing infection.
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Affiliation(s)
- Michael Lebens
- Department of Medical Microbiology and Immunology, University of Göteborg, SE-431 46 Göteborg, Sweden.
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Abstract
Membrane transport systems for P(i) transport are key elements in maintaining homeostasis of P(i) in organisms as diverse as bacteria and human. Two Na-P(i) cotransporter families with well-described functional properties in vertebrates, namely NaPi-II and NaPi-III, show conserved structural features with prokaryotic origin. A clear vertical relationship can be established among the mammalian protein family NaPi-III, a homologous system in C. elegans, the yeast system Pho89, and the bacterial P(i) transporter Pit. An alternative lineage connects the mammalian NaPi-II-related transporters with homologous proteins from Caenorhabditis elegans and Vibrio cholerae. The present review focuses on the molecular evolution of the NaPi-II protein family. Preliminary results indicate that the NaPi-II homologue cloned from V. cholerae is indeed a functional P(i) transporter when expressed in Xenopus oocytes. The closely related NaPi-II isoforms NaPi-IIa and NaPi-IIb are responsible for regulated epithelial Na-dependent P(i) transport in all vertebrates. Most species express two different NaPi-II proteins with the exception of the flounder and Xenopus laevis, which rely on only a single isoform. Using an RT-PCR-based approach with degenerate primers, we were able to identify NaPi-II-related mRNAs in a variety of vertebrates from different families. We hypothesize that the original NaPi-IIb-related gene was duplicated early in vertebrate development. The appearance of NaPi-IIa correlates with the development of the mammalian nephron.
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Affiliation(s)
- A Werner
- Department of Physiological Sciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, United Kingdom.
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Murer H, Hernando N, Forster I, Biber J. Proximal tubular phosphate reabsorption: molecular mechanisms. Physiol Rev 2000; 80:1373-409. [PMID: 11015617 DOI: 10.1152/physrev.2000.80.4.1373] [Citation(s) in RCA: 390] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Renal proximal tubular reabsorption of P(i) is a key element in overall P(i) homeostasis, and it involves a secondary active P(i) transport mechanism. Among the molecularly identified sodium-phosphate (Na/P(i)) cotransport systems a brush-border membrane type IIa Na-P(i) cotransporter is the key player in proximal tubular P(i) reabsorption. Physiological and pathophysiological alterations in renal P(i) reabsorption are related to altered brush-border membrane expression/content of the type IIa Na-P(i) cotransporter. Complex membrane retrieval/insertion mechanisms are involved in modulating transporter content in the brush-border membrane. In a tissue culture model (OK cells) expressing intrinsically the type IIa Na-P(i) cotransporter, the cellular cascades involved in "physiological/pathophysiological" control of P(i) reabsorption have been explored. As this cell model offers a "proximal tubular" environment, it is useful for characterization (in heterologous expression studies) of the cellular/molecular requirements for transport regulation. Finally, the oocyte expression system has permitted a thorough characterization of the transport characteristics and of structure/function relationships. Thus the cloning of the type IIa Na-P(i )cotransporter (in 1993) provided the tools to study renal brush-border membrane Na-P(i) cotransport function/regulation at the cellular/molecular level as well as at the organ level and led to an understanding of cellular mechanisms involved in control of proximal tubular P(i) handling and, thus, of overall P(i) homeostasis.
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Affiliation(s)
- H Murer
- Institute of Physiology, University of Zürich, Zürich, Switzerland.
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