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Zhuo MQ, Lv WH, Xu YH, Luo Z. Isolation and Characterization of Three Sodium-Phosphate Cotransporter Genes and Their Transcriptional Regulation in the Grass Carp Ctenopharyngodon idella. Int J Mol Sci 2020; 21:E8228. [PMID: 33153158 PMCID: PMC7662828 DOI: 10.3390/ijms21218228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/31/2020] [Accepted: 11/02/2020] [Indexed: 12/20/2022] Open
Abstract
It is important to explore the regulatory mechanism of phosphorus homeostasis in fish, which help avoid the risk of P toxicity and prevent P pollution in aquatic environment. The present study obtained the full-length cDNA sequences and the promoters of three SLC20 members (slc20a1a, slc20a1b and slc20a2) from grass carp Ctenopharyngodon idella, and explored their responses to inorganic phosphorus (Pi). Grass carp SLC20s proteins possessed conservative domains and amino acid sites relevant with phosphorus transport. The mRNAs of three slc20s appeared in the nine tissues, but their expression levels were tissue-dependent. The binding sites of three transcription factors (SREBP1, NRF2 and VDR) were predicted on the slc20s promoters. The mutation and EMSA analysis indicated that: (1) SREBP1 binding site (-783/-771 bp) negatively but VDR (-260/-253 bp) binding site positively regulated the activities of slc20a1a promoter; (2) SREBP1 (-1187/-1178 bp), NRF2 (-572/-561 bp) and VDR(615/-609 bp) binding sites positively regulated the activities of slc20a1b promoter; (3) SREBP1 (-987/-977 bp), NRF2 (-1469/-1459 bp) and VDR (-1124/-1117 bp) binding sites positively regulated the activities of the slc20a2 promoter. Moreover, Pi incubation significantly reduced the activities of three slc20s promoters, and Pi-induced transcriptional inactivation of slc20s promoters abolished after the mutation of the VDR element but not SREBP1 and NRF2 elements. Pi incubation down-regulated the mRNA levels of three slc20s. For the first time, our study elucidated the transcriptional regulatory mechanisms of SLC20s and their responses to Pi, which offered new insights into the Pi homeostatic regulation and provided the basis for reducing phosphorus discharge into the waters.
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Affiliation(s)
- Mei-Qin Zhuo
- Laboratory of Molecular Nutrition for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; (M.-Q.Z.); (W.-H.L.); (Y.-H.X.)
- School of Animal Science and Nutritional Engineering, Wuhan Polytechnic University, Wuhan 430023, China
| | - Wu-Hong Lv
- Laboratory of Molecular Nutrition for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; (M.-Q.Z.); (W.-H.L.); (Y.-H.X.)
| | - Yi-Huan Xu
- Laboratory of Molecular Nutrition for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; (M.-Q.Z.); (W.-H.L.); (Y.-H.X.)
| | - Zhi Luo
- Laboratory of Molecular Nutrition for Aquatic Economic Animals, Fishery College, Huazhong Agricultural University, Wuhan 430070, China; (M.-Q.Z.); (W.-H.L.); (Y.-H.X.)
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Shukla J, Mittal BR. Dimercaptosuccinic acid: A multifunctional cost effective agent for imaging and therapy. Indian J Nucl Med 2015; 30:295-302. [PMID: 26430311 PMCID: PMC4579612 DOI: 10.4103/0972-3919.164015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Dimercaptosuccinic acid (DMSA) is an analog of dimercaprol used as metal chelating moiety in variety of conditions. In nuclear medicine itself two types of Tc-99m DMSA complexes are used, trivalent and pentavalent forms. In this review, we have discussed the mechanism of uptake of both complexes as well as diagnostic and therapeutic application in a clinical scenario.
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Affiliation(s)
- Jaya Shukla
- Department of Nuclear Medicine and PET, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Bhagwant Rai Mittal
- Department of Nuclear Medicine and PET, Post Graduate Institute of Medical Education and Research, Chandigarh, India
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Labonté ED, Carreras CW, Leadbetter MR, Kozuka K, Kohler J, Koo-McCoy S, He L, Dy E, Black D, Zhong Z, Langsetmo I, Spencer AG, Bell N, Deshpande D, Navre M, Lewis JG, Jacobs JW, Charmot D. Gastrointestinal Inhibition of Sodium-Hydrogen Exchanger 3 Reduces Phosphorus Absorption and Protects against Vascular Calcification in CKD. J Am Soc Nephrol 2014; 26:1138-49. [PMID: 25404658 DOI: 10.1681/asn.2014030317] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 07/23/2014] [Indexed: 02/02/2023] Open
Abstract
In CKD, phosphate retention arising from diminished GFR is a key early step in a pathologic cascade leading to hyperthyroidism, metabolic bone disease, vascular calcification, and cardiovascular mortality. Tenapanor, a minimally systemically available inhibitor of the intestinal sodium-hydrogen exchanger 3, is being evaluated in clinical trials for its potential to (1) lower gastrointestinal sodium absorption, (2) improve fluid overload-related symptoms, such as hypertension and proteinuria, in patients with CKD, and (3) reduce interdialytic weight gain and intradialytic hypotension in ESRD. Here, we report the effects of tenapanor on dietary phosphorous absorption. Oral administration of tenapanor or other intestinal sodium-hydrogen exchanger 3 inhibitors increased fecal phosphorus, decreased urine phosphorus excretion, and reduced [(33)P]orthophosphate uptake in rats. In a rat model of CKD and vascular calcification, tenapanor reduced sodium and phosphorus absorption and significantly decreased ectopic calcification, serum creatinine and serum phosphorus levels, circulating phosphaturic hormone fibroblast growth factor-23 levels, and heart mass. These results indicate that tenapanor is an effective inhibitor of dietary phosphorus absorption and suggest a new approach to phosphate management in renal disease and associated mineral disorders.
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Affiliation(s)
| | | | | | | | | | | | - Limin He
- Ardelyx, Inc., Fremont, California
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Jin C, Zoidis E, Ghirlanda C, Schmid C. Dexamethasone and cyclic AMP regulate sodium phosphate cotransporter (NaPi-IIb and Pit-1) mRNA and phosphate uptake in rat alveolar type II epithelial cells. Lung 2009; 188:51-61. [PMID: 19806400 DOI: 10.1007/s00408-009-9183-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Accepted: 09/14/2009] [Indexed: 11/25/2022]
Abstract
Alveolar epithelial type II (AT II) cells need phosphate (Pi) for surfactant synthesis. The Na-dependent (Na(d)) Pi transporters NaPi-IIb and Pit-1 are expressed in lung, but their expression, regulation, and function in AT II cells remain unclear. We studied NaPi-IIb and Pit-1 mRNA expression in cultured AT II cells isolated from adult rat lung, their regulation by agents known to enhance surfactant production, dexamethasone (dex) and dibutyryl cyclic AMP (cAMP), and the effects of dex and cAMP on Na(d) Pi uptake by this cell type. By Northern analysis, cultured AT II cells expressed both NaPi-IIb (4.8 and 4.0 kb) and Pit-1 (4.3 kb) mRNA. Treatment with 100 nmol/l dex for 24 h decreased the expression of both mRNAs (to 0.48 +/- 0.06 and 0.77 +/- 0.05, respectively, as compared to control), while 0.1 mmol/l cAMP stimulated NaPi-IIb (1.94 +/- 0.22) but not Pit-1 mRNA (0.90 +/- 0.05, compared to vehicle-treated cells). NaPi-IIb and Pit-1 proteins could not be identified by western analysis of plasma membrane preparations of cultured AT II cells. AT II cells take up Pi in a Na(d) manner. Uptake was slightly (to 0.78-fold of the control) decreased by 100 nmol/l dex but not affected by 0.1 mmol/l cAMP treatment. Although NaPi-IIb mRNA expression was maintained to some extent by AT II cells kept in primary culture, Pi uptake was more closely related to Pit-1 mRNA expression.
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Affiliation(s)
- Chengluo Jin
- Division of Endocrinology and Diabetology, Department of Internal Medicine, University Hospital, 8091, Zurich, Switzerland
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Villa-Bellosta R, Ravera S, Sorribas V, Stange G, Levi M, Murer H, Biber J, Forster IC. The Na+-Pi cotransporter PiT-2 (SLC20A2) is expressed in the apical membrane of rat renal proximal tubules and regulated by dietary Pi. Am J Physiol Renal Physiol 2009; 296:F691-9. [PMID: 19073637 PMCID: PMC2670642 DOI: 10.1152/ajprenal.90623.2008] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2008] [Accepted: 12/08/2008] [Indexed: 12/26/2022] Open
Abstract
The principal mediators of renal phosphate (P(i)) reabsorption are the SLC34 family proteins NaPi-IIa and NaPi-IIc, localized to the proximal tubule (PT) apical membrane. Their abundance is regulated by circulatory factors and dietary P(i). Although their physiological importance has been confirmed in knockout animal studies, significant P(i) reabsorptive capacity remains, which suggests the involvement of other secondary-active P(i) transporters along the nephron. Here we show that a member of the SLC20 gene family (PiT-2) is localized to the brush-border membrane (BBM) of the PT epithelia and that its abundance, confirmed by Western blot and immunohistochemistry of rat kidney slices, is regulated by dietary P(i). In rats treated chronically on a high-P(i) (1.2%) diet, there was a marked decrease in the apparent abundance of PiT-2 protein in kidney slices compared with those from rats kept on a chronic low-P(i) (0.1%) diet. In Western blots of BBM from rats that were switched from a chronic low- to high-P(i) diet, NaPi-IIa showed rapid downregulation after 2 h; PiT-2 was also significantly downregulated at 24 h and NaPi-IIc after 48 h. For the converse dietary regime, NaPi-IIa showed adaptation within 8 h, whereas PiT-2 and NaPi-IIc showed a slower adaptive trend. Our findings suggest that PiT-2, until now considered as a ubiquitously expressed P(i) housekeeping transporter, is a novel mediator of P(i) reabsorption in the PT under conditions of acute P(i) deprivation, but with a different adaptive time course from NaPi-IIa and NaPi-IIc.
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Affiliation(s)
- Ricardo Villa-Bellosta
- Institute of Physiology, Univ. of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
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Denoyer D, Perek N, Le Jeune N, Frere D, Dubois F. Evidence that 99mTc-(V)-DMSA uptake is mediated by NaPi cotransporter type III in tumour cell lines. Eur J Nucl Med Mol Imaging 2003; 31:77-84. [PMID: 14557898 DOI: 10.1007/s00259-003-1334-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2003] [Accepted: 08/18/2003] [Indexed: 11/27/2022]
Abstract
In vivo studies have demonstrated that pentavalent technetium-99m dimercaptosuccinic acid [(99m)Tc-(V)-DMSA] may be a useful tumour imaging agent. Several studies have suggested that (99m)Tc-(V)-DMSA uptake may be related to the structural similarity between the (99m)Tc-(V)-DMSA core and the PO(4)(3-) anion. As phosphate ions enter cells via NaPi cotransporters, we investigated whether (99m)Tc-(V)-DMSA uptake is mediated by NaPi cotransporters. (99m)Tc-(V)-DMSA and phosphate uptake kinetics were compared in three cancer cell lines (MCF-7, G152 and MG-63) under several conditions (with and without sodium and NaPi cotransporter inhibitor and at different pH). Determination of molecular NaPi cotransporter mRNA expression was performed by reverse-transcriptase polymerase chain reaction (Rt-PCR) assay. Results obtained in the presence of NaPi inhibitor, in sodium-free medium and at alkaline pH showed that (99m)Tc-(V)-DMSA accumulation is linked to NaPi cotransporter functionality. MCF-7 and G152 exhibited the same tracer uptake, whereas MG-63 showed the highest phosphate accumulation and the lowest (99m)Tc-(V)-DMSA uptake. These results were in accordance with mRNA NaPi expression, i.e. all cell lines expressed NaPi type III but MG-63 also co-expressed NaPi type I. The total level of NaPi cotransporter was highly correlated with phosphate accumulation, while the level of type III was related to (99m)Tc-(V)-DMSA uptake. We have demonstrated that (99m)Tc-(V)-DMSA uptake is specifically mediated by NaPi type III in cancer cells.
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Affiliation(s)
- Delphine Denoyer
- Laboratory of Biophysics and Radiopharmaceuticals, Cell Death and Neoplasia Group, Faculty of Medicine, University of Saint Etienne, 15 rue Ambroise Paré, 42023 Saint-Etienne cedex 02, France.
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Abstract
The physiological tuning and pathophysiological alterations of renal proximal reabsorption of inorganic phosphate can be ascribed to the net amount of the Na/Pi-cotransporter NaPi-IIa localized in the brush border membrane. The net amount of NaPi-IIa appears to be the result of an endocytotic rate regulated by a complex network of different protein kinases. New approaches demonstrated that NaPi-IIa is part of heteromeric protein complexes, organized by PDZ (postsynaptic protein PSD95, Drosophila junction protein Disc-large, tight junction protein ZO-1) proteins. Such complexes are thought to play important roles in the apical positioning and regulated endocytosis of NaPi-IIa and therefore such interactions have to be considered when explaining proximal phosphate ion reabsorption.
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Affiliation(s)
- Heini Murer
- Institute of Physiology, University Zürich, 8057 Switzerland.
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