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![The transport of urate by hNPT4. A, [ 14 C]urate uptake in water(open columns) and hNPT4_L-injected (closed columns) oocytes for 1.0 h in basal and high potassium uptake solution with 50 M [ 14 C]urate. *, p 0.05; ***, p 0.001 versus the uptake by water-injected oocytes. ###, p 0.001 versus the uptake in basal (NaCl) solution. B, time dependence of [ 14 C]urate uptake. Water-(open circles) and hNPT4_L-injected (closed squares) oocytes were incubated in 50 M [ 14 C]urate in high potassium solution for various times (5, 15, 30, 60, and 120 min). C, time dependence of [ 14 C]urate efflux in water-(open circles) and hNPT4_L-injected (closed circles) oocytes. The efflux was determined from oocytes preinjected with 50 nl of [ 14 C]urate at 5, 15, 30, 60, and 90 min. The data were expressed as percentages of radioactivity when the initial radioactivity in an oocyte is equal to 100%. D, the electrophysiological measurement of PAH and urate current by water-and hNPT4_L-injected oocytes. PAH (5.0 mM) and urate (4.0 mM) were superfused over oocytes, and the current was recorded during voltage clamp at 20 mV. The data are the means S.E., n 10. ***, p 0.001 versus control. E, hNPT4_L-mediated [ 14 C]urate efflux in various compositions of extracellular solution. The oocytes were preinjected with 50 nl of [ 14 C]urate and determined the efflux in varying composition of extracellular solution as mentioned in Fig. 5 for 1.0 h. The data are the means S.E. of the subtracted values of the efflux in water-injected oocytes from that of oocytes expressing hNPT4_L, n 5. *, p 0.05 versus the value in NaCl.](profile/Promsuk-Jutabha/publication/46110369/figure/fig4/AS:667768584142848@1536219845007/The-transport-of-urate-by-hNPT4-A-14-Curate-uptake-in-wateropen-columns-and.png)
The transport of urate by hNPT4. A, [ 14 C]urate uptake in water(open columns) and hNPT4_L-injected (closed columns) oocytes for 1.0 h in basal and high potassium uptake solution with 50 M [ 14 C]urate. *, p 0.05; ***, p 0.001 versus the uptake by water-injected oocytes. ###, p 0.001 versus the uptake in basal (NaCl) solution. B, time dependence of [ 14 C]urate uptake. Water-(open circles) and hNPT4_L-injected (closed squares) oocytes were incubated in 50 M [ 14 C]urate in high potassium solution for various times (5, 15, 30, 60, and 120 min). C, time dependence of [ 14 C]urate efflux in water-(open circles) and hNPT4_L-injected (closed circles) oocytes. The efflux was determined from oocytes preinjected with 50 nl of [ 14 C]urate at 5, 15, 30, 60, and 90 min. The data were expressed as percentages of radioactivity when the initial radioactivity in an oocyte is equal to 100%. D, the electrophysiological measurement of PAH and urate current by water-and hNPT4_L-injected oocytes. PAH (5.0 mM) and urate (4.0 mM) were superfused over oocytes, and the current was recorded during voltage clamp at 20 mV. The data are the means S.E., n 10. ***, p 0.001 versus control. E, hNPT4_L-mediated [ 14 C]urate efflux in various compositions of extracellular solution. The oocytes were preinjected with 50 nl of [ 14 C]urate and determined the efflux in varying composition of extracellular solution as mentioned in Fig. 5 for 1.0 h. The data are the means S.E. of the subtracted values of the efflux in water-injected oocytes from that of oocytes expressing hNPT4_L, n 5. *, p 0.05 versus the value in NaCl.
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![FIGURE 9. The transport of urate by hNPT4. A, [ 14 C]urate uptake in...](profile/Promsuk-Jutabha/publication/46110369/figure/fig4/AS:667768584142848@1536219845007/The-transport-of-urate-by-hNPT4-A-14-Curate-uptake-in-wateropen-columns-and_Q320.jpg)
The evolutionary loss of hepatic urate oxidase (uricase) has resulted in humans with elevated serum uric acid (urate). Uricase
loss may have been beneficial to early primate survival. However, an elevated serum urate has predisposed man to hyperuricemia,
a metabolic disturbance leading to gout, hypertension, and various cardiovascular diseases. Hum...
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... caused not only by the reduction of extracellular fluid but also by sharing the renal tubular secretion pathway with urate (23). Because hNPT4 interacted strongly with loop diuretics, we examined urate transport via hNPT4_L in oocytes to identify the mechanism responsible for diuretic-induced hyperuricemia. We observed KCl- enhanced urate uptake (Fig. 9A) in hNPT4_L-expressing oocytes. Sim- ilar to PAH, time-dependent [ 14 C]urate uptake and efflux was observed (Fig. 9, B and C); however, because of its low water solubility, we could not determine the K m for urate. Applying urate to the bath solution induced currents under the voltage clamp conditions (Fig. 9D). Urate efflux via NPT4 ...
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... urate (23). Because hNPT4 interacted strongly with loop diuretics, we examined urate transport via hNPT4_L in oocytes to identify the mechanism responsible for diuretic-induced hyperuricemia. We observed KCl- enhanced urate uptake (Fig. 9A) in hNPT4_L-expressing oocytes. Sim- ilar to PAH, time-dependent [ 14 C]urate uptake and efflux was observed (Fig. 9, B and C); however, because of its low water solubility, we could not determine the K m for urate. Applying urate to the bath solution induced currents under the voltage clamp conditions (Fig. 9D). Urate efflux via NPT4 is depressed by replacement of external Na with K (Fig. 9E). Dose-dependent inhibitory effects of loop diuretics on ...
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... observed KCl- enhanced urate uptake (Fig. 9A) in hNPT4_L-expressing oocytes. Sim- ilar to PAH, time-dependent [ 14 C]urate uptake and efflux was observed (Fig. 9, B and C); however, because of its low water solubility, we could not determine the K m for urate. Applying urate to the bath solution induced currents under the voltage clamp conditions (Fig. 9D). Urate efflux via NPT4 is depressed by replacement of external Na with K (Fig. 9E). Dose-dependent inhibitory effects of loop diuretics on hNPT4-mediated urate uptake were observed (IC 50 was 223.5 1.5 M for bumetanide and 73.5 1.5 M for furosemide) (Fig. 8, D and E). These results suggest that hNPT4 functions as a luminal ...
Context 4
... to PAH, time-dependent [ 14 C]urate uptake and efflux was observed (Fig. 9, B and C); however, because of its low water solubility, we could not determine the K m for urate. Applying urate to the bath solution induced currents under the voltage clamp conditions (Fig. 9D). Urate efflux via NPT4 is depressed by replacement of external Na with K (Fig. 9E). Dose-dependent inhibitory effects of loop diuretics on hNPT4-mediated urate uptake were observed (IC 50 was 223.5 1.5 M for bumetanide and 73.5 1.5 M for furosemide) (Fig. 8, D and E). These results suggest that hNPT4 functions as a luminal voltage-dependent exit pathway for urate as well as other anionic substrates in the proximal ...
Citations
... With regard to SLC2A9 and serum urate, 59 publications have been deposited in the GWAS Catalog up until March 11, 2023, with two studies 44,45 reporting on GEIs (interaction effects between genes and serum urate on bone mineral density and type 2 diabetes mellitus). In the literature, 17,[46][47][48][49] several studies have also reported/reviewed SLC2A9 interactions involving thiazides/diuretics. One of the studies, a primary study, 17 reported that the SLC2A9 intron rs13129697 SNP significantly (P = 0.010) interacted with thiazides/loop diuretic use and selfreported incident gout in 3,524 hypertensive participants. ...
Thiazide diuretics, widely used in hypertension, cause a variety of adverse reactions, including hyperglycemia, hyperuricemia, and electrolyte abnormalities. In this study, we aimed to identify genetic variants that interact with thiazide‐use to increase the risk of these adverse reactions. Using UK Biobank data, we first performed genomewide variance quantitative trait locus (vQTL) analysis of ~ 6.2 million SNPs on 95,493 unrelated hypertensive White British participants (24,313 on self‐reported bendroflumethiazide treatment at recruitment) for 2 blood (glucose and urate) and 2 urine (potassium and sodium) biomarkers. Second, we conducted direct gene–environment interaction (GEI) tests on the significant ( P < 2.5 × 10 ⁻⁹ ) vQTLs, included a second UK Biobank cohort comprising 13,647 unrelated hypertensive White British participants (3,478 on thiazides other than bendroflumethiazide) and set significance at P = 0.05 divided by the number of vQTL SNPs tested for GEIs. The vQTL analysis identified eight statistically significant SNPs for blood glucose (5 SNPs) and serum urate (3 SNPs), with none being identified for the urinary biomarkers. Two of the SNPs (1 glucose SNP: CDKAL1 intron rs35612982, GEI P = 6.24 × 10 ⁻³ ; and 1 serum urate SNP: SLC2A9 intron rs938564, GEI P = 4.51 × 10 ⁻⁴ ) demonstrated significant GEI effects in the first, but not the second, cohort. Both genes are biologically plausible candidates, with the SLC2A9 ‐mediated interaction having been previously reported. In conclusion, we used a two‐stage approach to detect two biologically plausible genetic loci that can interact with thiazides to increase the risk of thiazide‐associated biochemical abnormalities. Understanding how environmental exposures (including medications such as thiazides) and genetics interact, is an important step toward precision medicine and improved patient outcomes.
... In physiological conditions, the transporters are proposed to be unidirectional based on transport affinity and substrate availability both outside and inside the cells [8,13]. Table 1 summarizes the eight transporters in terms of their transport systems, substrates, affinities (K m ) for urate, and average expressions in the clusters of PT and DL [9,10,12,[31][32][33][34][35][36][37][38], demonstrating that these transporters can be classified based on their cellular functions for urate transport. ...
... Another example is the change in cellular transport direction given the reversal property of some transporters in human kidneys ( Fig. 5C: right panel). Bidirectional functions of urate transporters in vitro have been previously reported [9,31,33,34]. By contrast, urate transporters in physiological conditions are proposed to be restricted to unidirectional transport based on the transport affinity and substrate availability both outside and inside of the cells [8,13]. ...
In humans, uric acid is an end-product of purine metabolism. Urate excretion from the human kidney is tightly regulated by reabsorption and secretion. At least eleven genes have been identified as human renal urate transporters. However, it remains unclear whether all renal tubular cells express the same set of urate transporters. Here, we show renal tubular cells are divided into three distinct cell populations for urate handling. Analysis of healthy human kidneys at single-cell resolution revealed that not all tubular cells expressed the same set of urate transporters. Only 32% of tubular cells were related to both reabsorption and secretion, while the remaining tubular cells were related to either reabsorption or secretion at 5% and 63%, respectively. These results provide physiological insight into the molecular function of the transporters and renal urate handling on single-cell units. Our findings suggest that three different cell populations cooperate to regulate urate excretion from the human kidney, and our proposed framework is a step forward in broadening the view from the molecular to the cellular level of transport capacity.
... In the kidney, we identified two solute carriers (SLC16A12 and SLC47A1) that were solely upregulated via translation relative to liver or muscle, and one solute carrier (SLC17A3) upregulated at both transcriptional and translational levels compared to liver (Figures 3A, B). Solute carriers (SLC) are a family of proteins that are responsible for the majority of absorption, distribution, and clearance of ions/organic molecules within the renal tubule (Jutabha et al., 2010;Lewis et al., 2021;Verouti et al., 2021). Furthermore, SDHB was translationally upregulated in the kidney compared to muscle and knockout of SDBH has been shown to inhibit the TCA cycle (Fang et al., 2021). ...
Introduction: Translation is a crucial stage of gene expression. It may also act as an additional layer of regulation that plays an important role in gene expression and function. Highly expressed genes are believed to be codon-biased to support increased protein production, in which quickly translated codons correspond to highly abundant tRNAs. Synonymous SNPs, considered to be silent due to the degeneracy of the genetic code, may shift protein abundance and function through alterations in translational efficiency and suboptimal pairing to lowly abundant tRNAs.
Methods: Here, we applied Quantitative Mature tRNA sequencing (QuantM-tRNAseq) and ribosome profiling across bovine tissues in order to investigate the relationship between tRNA expression and slowed translation.
Results: Moreover, we have identified genes modulated at transcriptional and/or translational levels underlying tissue-specific biological processes. We have also successfully defined pausing sites that depict the regulatory information encoded within the open reading frame of transcripts, which could be related to translation rate and facilitate proper protein folding. This work offers an atlas of distinctive pausing sites across three bovine tissues, which provides an opportunity to predict codon optimality and understand tissue-specific mechanisms of regulating protein synthesis.
... revealed two candidate genes-SLC17A1 and SLC17A3. Both genes are primarily involved in urate metabolism and transport 47,48 . Given that 50% of patients with T1D are prone to developing diabetic kidney disease and that serum uric acid may be a modifiable risk factor of nephropathy in T1D [49][50][51] , the identification of a genetic variant that affects urate concentration is of high clinical significance, especially that high uric acid level has been implicated in β-cell dysfunction 52 Our study can potentially contribute to the predictive roles of SCL17A1 rs1165196 and SLC17A3 rs942379 variants in the early diagnosis and prediction of T1D and its complications, particularly diabetic kidney disease. ...
Type 1 diabetes (T1D) is characterized by the progressive destruction of pancreatic β-cells, leading to insulin deficiency and lifelong dependency on exogenous insulin. Higher estimates of heritability rates in monozygotic twins, followed by dizygotic twins and sib-pairs, indicate the role of genetics in the pathogenesis of T1D. The incidence and prevalence of T1D are alarmingly high in Kuwait. Consanguineous marriages account for 50–70% of all marriages in Kuwait, leading to an excessive burden of recessive allele enrichment and clustering of familial disorders. Thus, genetic studies from this Arab region are expected to lead to the identification of novel gene loci for T1D. In this study, we performed linkage analyses to identify the recurrent genetic variants segregating in high-risk Kuwaiti families with T1D. We studied 18 unrelated Kuwaiti native T1D families using whole exome sequencing data from 86 individuals, of whom 37 were diagnosed with T1D. The study identified three potential loci with a LOD score of ≥ 3, spanning across four candidate genes, namely SLC17A1 (rs1165196:pT269I), SLC17A3 (rs942379: p.S370S), TATDN2 (rs394558:p.V256I), and TMEM131L (rs6848033:p.R190R). Upon examination of missense variants from these genes in the familial T1D dataset, we observed a significantly increased enrichment of the genotype homozygous for the minor allele at SLC17A3 rs56027330_p.G279R accounting for 16.2% in affected children from 6 unrelated Kuwaiti T1D families compared to 1000 genomes Phase 3 data (0.9%). Data from the NephQTL database revealed that the rs1165196, rs942379, rs394558, and rs56027330 SNPs exhibited genotype-based differential expression in either glomerular or tubular tissues. Data from the GTEx database revealed rs942379 and rs394558 as QTL variants altering the expression of TRIM38 and IRAK2 respectively. Global genome-wide association studies indicated that SLC17A1 rs1165196 and other variants from SLC17A3 are associated with uric acid concentrations and gout. Further evidence from the T1D Knowledge portal supported the role of shortlisted variants in T1D pathogenesis and urate metabolism. Our study suggests the involvement of SLC17A1, SLC17A3, TATDN2, and TMEM131L genes in familial T1D in Kuwait. An enrichment selection of genotype homozygous for the minor allele is observed at SLC17A3 rs56027330_p.G279R variant in affected members of Kuwaiti T1D families. Future studies may focus on replicating the findings in a larger T1D cohort and delineate the mechanistic details of the impact of these novel candidate genes on the pathophysiology of T1D.
... It plays a crucial role as a pathway for urate elimination and is primarily located on the apical side of renal proximal tubules. NPT4 interacts significantly with loop diuretics such as furosemide and bumetanide [96]. ...
... Certain variants of the NPT4, namely N68H and F304S, have been found to result in reduced urate efflux [96]. This suggests that these genetic variations have an impact on the function of NPT4 and contribute to altered urate levels. ...
The increasing incidence of ischemic stroke emphasizes the necessity for early detection and preventive strategies. Diagnostic biomarkers currently available for ischemic stroke only become detectable shortly before the manifestation of stroke symptoms. Genetic variants associated with ischemic stroke offer a potential solution to address this diagnostic limitation. However, it is crucial to acknowledge that genetic variants cannot be modified in the same way as epigenetic changes. Nevertheless, individuals carrying risk or protective variants can modify their lifestyle to potentially influence the associated epigenetic factors. This study aims to summarize specific variants relevant to Asian populations that may aid in the early detection of ischemic stroke and explore their impact on the disease's pathophysiology. These variants give us important information about the genes that play a role in ischemic stroke by affecting things like atherosclerosis pathway, blood coagulation pathway, homocysteine metabolism, transporter function, transcription, and the activity of neurons regulation. It is important to recognize the variations in genetic variants among different ethnicities and avoid generalizing the pathogenesis of ischemic stroke.
... It is classified as type 1 or type 2 depending on the mutated transporter, urate transporter 1 (URAT1) 1 or glucose transporter 9 (GLUT9), respectively 2 More renal uric acid transporters have been identified, both on the apical and basolateral sides of the proximal tubular cell membranes. 3,4 Other than URAT1 and GLUT9, only ATP-binding cassette transporter G2 codified by the ABCG2 gene 5 and sodium-dependent phosphate transporters type 1 and 4 encoded respectively by the SLC17A1 and SLC17A3 genes, have been related to human diseases but they present with hyperuricemia and gout and not hypouricemia. 4,6 Nevertheless, there are reports of cases clinically diagnosed as RHUC without genetic resolution, suggesting that other transporters may be implicated diseases related with defects on renal UA handling. ...
... 3,4 Other than URAT1 and GLUT9, only ATP-binding cassette transporter G2 codified by the ABCG2 gene 5 and sodium-dependent phosphate transporters type 1 and 4 encoded respectively by the SLC17A1 and SLC17A3 genes, have been related to human diseases but they present with hyperuricemia and gout and not hypouricemia. 4,6 Nevertheless, there are reports of cases clinically diagnosed as RHUC without genetic resolution, suggesting that other transporters may be implicated diseases related with defects on renal UA handling. 7 Incidence of RHUC has been estimated to be inferior to 1%, mostly from studies on the Asian population 8,9 but populations from other geographic areas are also affected. ...
Renal hypouricemia (RHUC) is an autosomal recessive disease caused by the dysfunction of uric acid (UA) transporters in the proximal
tubule causing increased fractional excretion of uric acid (FEUA). It is associated with mutations of SLC22A12 that codifies for URAT1, involved
in RHUC type 1, or SLC2A9 which codifies for GLUT9 and is involved in RHUC type 2. We present the case of a man diagnosed with RHUC type
2 following hospitalization for acute kidney injury (AKI).
A 43-year-old was hospitalized due to AKI after a 20 km walk at an outdoor temperature of 30°C. On the objective examination, he was
dehydrated. Blood tests presented severe azotemia (creatininemia 16.43 mg/dL, uremia 254 mg/dL), UA 3.6 mg/dL, fosfatemia 6 mg/dL,
Na 138 mEq/L, K 4.2 mEq/L, Cl 102 mEq/l, arterial gasometry with pH 7.35, pCO2 36 mmHg, HCO3 20 mmol/L, lactates 1.4 mmol/L. Urine test
with proteinuria and unremarkable sediment. His kidneys had foci of microlithiasis. He started vigorous fluid therapy and sustained improvement
in renal function was seen, with no need for renal function replacement therapy. The subsequent evaluation showed hypouricemia
... Serum uric acid levels are affected by several drugs through transporters. Loop diuretics and thiazide diuretics decrease uric acid excretion by both decreasing extracellular fluid volume and glomerular filtration rate and inhibiting uric acid secretion via NPT4 [28,29]. Losartan, an angiotensin II receptor blocker (ARB) [23,30], and calcium channel blockers (CCBs) [31] also inhibit URAT1 and increase uric acid excretion. ...
The importance of uric acid, the final metabolite of purines excreted by the kidneys and intestines, was not previously recognized, except for its role in forming crystals in the joints and causing gout. However, recent evidence implies that uric acid is not a biologically inactive substance and may exert a wide range of effects, including antioxidant, neurostimulatory, proinflammatory, and innate immune activities. Notably, uric acid has two contradictory properties: antioxidant and oxidative ones. In this review, we present the concept of “dysuricemia”, a condition in which deviation from the appropriate range of uric acid in the living body results in disease. This concept encompasses both hyperuricemia and hypouricemia. This review draws comparisons between the biologically biphasic positive and negative effects of uric acid and discusses the impact of such effects on various diseases.
... About two-thirds of all UA in humans is excreted in urine and one-third in the gastrointestinal tract [38]. Urate transporter 1, which is located on the luminal side of proximal tube cells (URAT1; SLC22A12), reabsorbs filtered UA at the glomerular level [39], while glucose transporter 9 (GLUT9; SLC2A9), through the basal side of cells, allows intracellular UA to exit (Table 1) [36,40]; otherwise, UA secretion may be mediated by ATP-binding cassette transporter subfamily G member 2 (ABCG2) and sodium-dependent phosphate transporter 1 (NPT1; SLC17A1) and 4 (NPT4; SLC17A3) [41,42]. Interestingly, studies on polymorphisms of these transporters suggest that renal overload hyperuricemia is a novel pathophysiological mechanism in gout [43,44]. ...
Purines, such as adenine and guanine, perform several important functions in the cell. They are found in nucleic acids; are structural components of some coenzymes, including NADH and coenzyme A; and have a crucial role in the modulation of energy metabolism and signal transduction. Moreover, purines have been shown to play an important role in the physiology of platelets, muscles, and neurotransmission. All cells require a balanced number of purines for growth, proliferation, and survival. Under physiological conditions, enzymes involved in purines metabolism maintain a balanced ratio between their synthesis and degradation in the cell. In humans, the final product of purine catabolism is uric acid, while most other mammals possess the enzyme uricase that converts uric acid to allantoin, which can be easily eliminated with urine. During the last decades, hyperuricemia has been associated with a number of human extra-articular diseases (in particular, the cardiovascular ones) and their clinical severity. In this review, we go through the methods of investigation of purine metabolism dysfunctions, looking at the functionality of xanthine oxidoreductase and the formation of catabolites in urine and saliva. Finally, we discuss how these molecules can be used as markers of oxidative stress.
... A study done by Jutabha P, et al., suggested that an orphan transporter hNPT4 (human sodium phosphate transporter 4; SLC17A3) was a multi-specific organic anion efflux transporter presented in the liver and kidneys. Human sodium phosphate transporter 4; positioned at the apical side of renal tubules and ruled as a voltage-driven urate transporter [91]. ...
... A study done by Jutabha P, et al., suggested that an orphan transporter hNPT4 (human sodium phosphate transporter 4; SLC17A3) was a multi-specific organic anion efflux transporter presented in the liver and kidneys. Human sodium phosphate transporter 4; positioned at the apical side of renal tubules and ruled as a voltage-driven urate transporter [91]. ...
