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SLC2A9 expression in human kidney. SLC2A9-S (A,D) or SLC2A9-L (G,J) was stained together with fluorescein-Lotus Tetragonolobus lectin (LTL; green) (B,H) or rhodamine-Dolichos Biflorus agglutinin (DBA; red) (E,K). Overlay images staining with nucleus (blue) and with phase contrast images were shown in C, F, I and L. The scale bar of 30 mm was shown in L. doi:10.1371/journal.pone.0084996.g003
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Many genome-wide association studies pointed out that SLC2A9 gene, which encodes a voltage-driven urate transporter, SLC2A9/GLUT9 (a.k.a. URATv1), as one of the most influential genes for serum urate levels. SLC2A9 is reported to encode two splice variants: SLC2A9-S (512 amino acids) and SLC2A9-L (540 amino acids), only difference being at their N-...
Contexts in source publication
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... kidney sections were stained with these antibodies together with fluorescein-Lotus Tetragonolobus lectin (LTL) or rhodamine -Dolichos Biflorus agglutinin (DBA) (Fig. 3); LTL specifically binds to renal proximal tubules and DBA specifically binds to collecting ducts. SLC2A9-S was expressed at the apical membrane of collecting ducts, which were stained with DBA ( Fig. 3D-F). In contrast, SLC2A9-L was expressed at the basolateral membrane of proximal tubules, which were positive for LTL (Fig. 3G-J). Some ...
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... were stained with these antibodies together with fluorescein-Lotus Tetragonolobus lectin (LTL) or rhodamine -Dolichos Biflorus agglutinin (DBA) (Fig. 3); LTL specifically binds to renal proximal tubules and DBA specifically binds to collecting ducts. SLC2A9-S was expressed at the apical membrane of collecting ducts, which were stained with DBA ( Fig. 3D-F). In contrast, SLC2A9-L was expressed at the basolateral membrane of proximal tubules, which were positive for LTL (Fig. 3G-J). Some PECAM-1 (Platelet Endothelial Cell Adhesion Molecule-1) positive endothelial cells expressed SLC2A9-S or -L (data not shown). Only weak background signal was obtained when immunostaining was performed ...
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... agglutinin (DBA) (Fig. 3); LTL specifically binds to renal proximal tubules and DBA specifically binds to collecting ducts. SLC2A9-S was expressed at the apical membrane of collecting ducts, which were stained with DBA ( Fig. 3D-F). In contrast, SLC2A9-L was expressed at the basolateral membrane of proximal tubules, which were positive for LTL (Fig. 3G-J). Some PECAM-1 (Platelet Endothelial Cell Adhesion Molecule-1) positive endothelial cells expressed SLC2A9-S or -L (data not shown). Only weak background signal was obtained when immunostaining was performed using these antibodies pre-incubated with their antigen peptides (data not ...
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... constructs of SLC2A9-S. GFP-tagged Short_16AAdel construct (green), which was deleted with N-terminal 16 amino acids from SLC2A9-S, was transfected into MDCK cells. Cell surface of the apical or basolateral membrane was biotinylated and visualized in red. Conforcal images of xy and z axes were obtained and the magnification is the same as Fig. 3. ...
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... in MDCK cells. B. GFP-tagged Long_32-36del (green), in which 32 nd -36 th amino acids including the putative di-leucine motif was deleted, were expressed in MDCK cells. Cell surface of the apical or basolateral membrane was biotinylated and visualized in red. Confocal images of xy and z axes were obtained and the magnification is the same as Fig. 3. doi:10.1371/journal.pone.0084996.g006 chimeric proteins. It is of note that when a mutant was targeted to both apical and basolateral membranes, it also ended up in the lysosome (Fig. 9), probably to be degraded. When 20 amino acids out of 21 unique N-terminal amino acids were removed from SLC2A9-S, the mutant was not expressed. These ...
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... or Long_27-31del (D), in which 5 amino acids from 27 th and 31 st were deleted, were transfected into MDCK cells. These GFP-tagged constructs were visualized in green. Cell surface of the apical or basolateral membrane was biotinylated and visualized in red. Confocal images of xy and z axes were obtained and the magnification is the same as Fig. 3. doi:10.1371/journal.pone.0084996.g007 prepared with lysozyme treatment, freeze-thaw cycle and sonica- tion in PBS. The extract was incubated with Glutathione Sepharose TM 4B beads (GE Healthcare Bio-Sciences Corp. Piscataway, NJ) for 6 hrs at 4uC. After incubation, these beads were washed 4 times with PBS and eluted with glutathione ...
Context 7
... or GFP-tagged Long_25-50del (B), in which amino acids from 25th to 50th were deleted from SLC2A9-L were expressed in MDCK cells. These constructs were visualized in green. Cell surface of the apical or basolateral membrane was biotinylated and visualized in red. Conforcal images of xy and z axes were obtained and the magnification is the same as Fig. 3. ...
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Citations
... For all transporters except SLC2A9, there was a consensus in the literature regarding their localization. We treated SLC2A9 as being localized on the apical side due to evidence that pinpointed the localization of human SLC2A9 in the PT region [45], although SLC2A9 may be present on both the apical and basolateral sides [46]. Given that the CUTE model is constructed based on the existing and current knowledge, we acknowledge that updates to the model might be required with new and upcoming findings on urate transporters. ...
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.
... [42] GLUT9 is a class 2 GLUT and plays a crucial role in urate reabsorption. [43] GLUT10 has its encoding gene on chromosome 20q12-q31, a locus also associated with non-insulin-dependent diabetes mellitus. erefore, GLUT10 has become an interesting center of attention for the development of more insight and therapeutic approaches for type-2 diabetes mellitus. ...
In the human body, glucose acts as a major energy-producing fuel and regulator of energy homeostasis, enzyme functions, and gene transcription. The selective permeability of the lipid bilayer structure of the cell membrane makes it mandatory for glucose to require transport proteins for its transit into the cells. These include solute carrier integral membrane proteins such as glucose transporters (GLUTs) and sodium-glucose transporters. GLUTs belong to the major facilitator superfamily with a 12 transmembrane spanner topology, with GLUT1–13 sharing the same transmembrane sequence but variable transmembrane loops and terminal cytoplasmic ends of carbon and nitrogen. Phylogenetic analysis classifies GLUTs into three classes, with each class showing an affinity for a specific substrate. The tightly coupled relationship between glucose homeostasis and the nearly ubiquitous GLUTs has led to the investigation of their diverse roles in embryonic development, adult physiology, and clinical disorders including but not limited to inborn errors, diabetes mellitus, metabolic syndrome, and cancers. The current review is pivoted around the studies focusing on the structure and functions of members of the GLUT family, their chromosomal and organ-specific distribution, as well as the current evidence of their clinical implications and prospective therapeutic roles, specifically in cancers and metabolic disorders. The literature for the present work was retrieved from databases including Google Scholar, Web of Science, and PubMed.
... SLC2A9 generates two GLUT9 isoforms by alternative pre-mRNA splicing, GLUT9L and GLUT9S, which differ only at their amino termini and contain 12 predicted transmembrane helices and cytoplasmic amino and carboxy termini [15][16][17]. In the kidney, GLUT9L is expressed at the basolateral membrane of the epithelial cells of the proximal tubule and is responsible for UA reabsorption, whereas GLUT9S is localized to the apical membrane of collecting duct cells [16,18]. Both the GLUT9 variants facilitate urate uptake [19]. ...
... Loss-of-function mutations in these two transporters impair UA reabsorption resulting in reduced serum levels of UA and increased UA levels in urine. Nevertheless, it has been reported that homozygous SLC2A9 mutations cause a more severe hypouricemia than homozygous SLC22A12 mutations [4,6,8,9,18,20]. This difference can be explained because the reabsorption of UA is mediated not only by URAT1 but also by other apical UA transporters like the organic anion transporters OAT4 and OAT10, whereas the UA release into to the blood is facilitated exclusively by the basolateral GLUT9L transporter [6]. ...
Renal hypouricemia (RHUC) is a rare hereditary disorder caused by loss-of-function mutations in the SLC22A12 (RHUC type 1) or SLC2A9 (RHUC type 2) genes, encoding urate transporters URAT1 and GLUT9, respectively, that reabsorb urate in the renal proximal tubule. The characteristics of this disorder are low serum urate levels, high renal fractional excretion of urate, and occasional severe complications such as nephrolithiasis and exercise-induced acute renal failure. In this study, we report two Spanish (Caucasian) siblings and a Pakistani boy with clinical characteristics compatible with RHUC. Whole-exome sequencing (WES) analysis identified two homozygous variants: a novel pathogenic SLC22A12 variant, c.1523G>A; p.(S508N), in the two Caucasian siblings and a previously reported SLC2A9 variant, c.646G>A; p.(G216R), in the Pakistani boy. Our findings suggest that these two mutations cause RHUC through loss of urate reabsorption and extend the SLC22A12 mutation spectrum. In addition, this work further emphasizes the importance of WES analysis in clinical settings.
... SLC2A9 is located at 4p16.1 and encodes the following two diferent isoforms: GLUT9-l (540 amino acid residues) and GLUT9-s (512 amino acid residues). Some studies [17] have found that the distribution of these two isoforms difers. GLUT9-l appears to be expressed mainly in the basement membrane of the proximal tubules of the kidney and in tissues such as the pancreas, with GLUT9-s being abundantly expressed in the parietal membrane of the renal collecting duct and in the placenta. ...
What Is Known and Objective. Elevated serum uric acid (SUA) is one of the most common adverse reactions during the administration of pyrazinamide, but patients exhibit significant individual differences. This study aimed to evaluate the relationship between gene polymorphisms and pyrazinamide-induced SUA elevation in Han Chinese tuberculosis patients. Methods. Tuberculosis patients treated with pyrazinamide were genotyped for the following three candidate genes: SLC22A12, SLC2A9, and ABCG2. Patients were divided into low-risk and high-risk groups according to the change of SUA after treatment. Intergroup comparisons were performed on clinical characteristics, allele and genotype frequencies, and haplotype distributions, and logistic regression analysis was used to explore the relevant risk factors. Results. In total, 143 patients were enrolled, including 83 in the high-risk groups and 60 in the low-risk groups. We observed a significant association between SLC2A9 polymorphism and pyrazinamide-induced SUA elevation. The G allele was significantly lower in the high-risk group than in the low-risk group (27.7% vs. 48.3%, OR = 0.410, 95% CI: 0.250–0.671, p < 0.001 ). Patients with the GA and GG genotypes were less likely to have SUA elevation than those with the AA genotype (OR = 0.125, 95% CI: 0.053–0.293, p < 0.001 and OR = 0.252, 95% CI: 0.074–0.851, p = 0.026 , respectively). Regarding SLC2A9 rs13129697, the frequency of the G allele was significantly lower in the high-risk group than in the low-risk group (26.1% vs. 40.8%, OR = 0.531, 95% CI: 0.312–0.842, p = 0.008 ). In the low-risk group, the proportion of patients with the TG genotype was significantly higher than that with the TT genotype (81.7% vs. 18.3%, OR = 0.279, 95% CI: 0.127–0.611, p = 0.001 ). Haplotype analysis revealed that patients with the SLC2A9 (rs1014290–rs13129697) GG haplotype had lower risk of SUA elevation than those with the AT haplotype (27.11% vs. 63.25%, p = 0.005 ). Furthermore, logistic regression analysis showed that drinking history was an independent risk factor for elevated SUA caused by PZA (OR = 3.943, 95% CI = 1.18–13.175, p = 0.026 ) and that the rs1014290 GA genotype might be a protective factor (OR = 0.094, 95% CI = 0.023–0.386, p = 0.001 ) after correction. What Is New and Conclusion. We found that SLC2A9 genetic polymorphisms were associated with elevated SUA caused by pyrazinamide. The G>A variant of rs1014290 and drinking history might be risk factors.
... GLUT9L is encoded by 12 exons and contains 540 amino acids, while GLUT9S is encoded by 13 exons and is comprised of 512 amino acids. In the kidney, GLUT9L localizes to the basolateral membrane of proximal tubule cells, while GLUT9S is expressed at the apical membrane of collecting duct cells [19,20]. GLUT9-mediated urate transport has been shown to be voltagedependent, an appropriate characteristic for urate efflux transport from the cell [12]. ...
Renal hypouricemia (RHUC) is a rare inherited disorder characterized by impaired urate reabsorption in the proximal tubule resulting in low urate serum levels and increased urate excretion. Some patients may present severe complications such as exercise-induced acute renal failure and nephrolithiasis. RHUC is caused by inactivating mutations in the SLC22A12 (RHUC type 1) or SLC2A9 (RHUC type 2) genes, which encode urate transporters URAT1 and GLUT9, respectively. In this study, our goal was to identify mutations associated with twenty-one new cases with RHUC through direct sequencing of SLC22A12 and SLC2A9 coding exons. Additionally, we carried out an SNPs-haplotype analysis to determine whether the rare SLC2A9 variant c.374C>T; p.(T125M), which is recurrent in Spanish families with RHUC type 2, had a common-linked haplotype. Six intragenic informative SNPs were analyzed using PCR amplification from genomic DNA and direct sequencing. Our results showed that ten patients carried the SLC22A12 mutation c.1400C>T; p.(T467M), ten presented the SLC2A9 mutation c.374C>T, and one carried a new SLC2A9 heterozygous mutation, c.593G>A; p.(R198H). Patients carrying the SLC2A9 mutation c.374C>T share a common-linked haplotype, confirming that it emerged due to a founder effect.
... 50 There is research demonstrating that SGLT-2i suppresses UA reabsorption in collecting ducts mediated by GLUT9. 51 Another mechanism may be that SGLT-2i reduces the reabsorption of UA via urate reabsorption protein 1 (URAT1) thereby reducing the concentration of serum insulin. Figure 3 shows the concrete mechanism. ...
... 50 There is research demonstrating that SGLT-2i suppresses UA reabsorption in collecting ducts mediated by GLUT9. 51 Another mechanism may be that SGLT-2i reduces the reabsorption of UA via urate reabsorption protein 1 (URAT1) thereby reducing the concentration of serum insulin. Figure 3 shows the concrete mechanism. ...
Hyperuricemia is a common comorbidity in patients with type 2 diabetes mellitus (T2DM), as insulin resistance (IR) or hyperinsulinemia is associated with higher serum uric acid (SUA) levels due to decreased uric acid (UA) secretion, and SUA vice
versa is an important risk factor that promotes the occurrence and progression of T2DM and its complications. Growing evidence
suggests that sodium-glucose cotransporter 2 inhibitors (SGLT-2i), a novel anti-diabetic drug initially developed to treat T2DM, may
exert favorable effects in reducing SUA. Currently, one of the possible mechanisms is that SGLT2i increases urinary glucose excretion,
probably inhibiting glucose transport 9 (GLUT9)-mediated uric acid reabsorption in the collecting duct, resulting in increased uric acid
excretion in exchange for glucose reabsorption. Regardless of this possible mechanism, the underlying comprehensive mechanisms
remain poorly elucidated. Therefore, in the present review, a variety of other potential mechanisms will be covered to identify the therapeutic role of SGLT-2i in hyperuricemia.
... We have previously reported that the N-terminal domain of GLUT9a has a regulatory function for iodine [26]. In the kidney, GLUT 9a is expressed on the basolateral side of the proximal tubule, while GLUT9b is expressed on the apical side of the collecting duct [27]. Placental GLUT9a and GLUT9b however co-localize with the villous (apical) membrane but not with the basal membrane of the syncytiotrophoblast [28]. ...
Hyperuricemia is a common feature in pregnancies compromised by pre-eclampsia, a pregnancy disease characterized by hypertension and proteinuria. The role of uric acid in the pathogenesis of pre-eclampsia remains largely unclear. The aim of this study was to investigate the effect of elevated uric acid serum levels during pregnancy on maternal blood pressure and neonatal outcome using two different murine knockout models. Non-pregnant liver-specific GLUT9 knockout (LG9KO) mice showed elevated uric acid serum concentrations but no hypertensive blood pressure levels. During pregnancy, however, blood pressure levels of these animals increased in the second and third trimester, and circadian blood pressure dipping was severely altered when compared to non-pregnant LG9KO mice. The impact of hyperuricemia on fetal development was investigated using a systemic GLUT9 knockout (G9KO) mouse model. Fetal hyperuricemia caused distinctive renal tissue injuries and, subsequently an impaired neonatal growth pattern. These findings provide strong evidence that hyperuricemia plays a major role in the pathogenesis of hypertensive pregnancy disorders such as pre-eclampsia. These novel insights may enable the development of preventive and therapeutic strategies for hyperuricemia-related diseases.
... Loss-of-function mutations in GLUT9 have been identified in familial hypouricemia, and SNPs are associated with reduced serum urate, indicating that GLUT9 is a major determinant of serum urate levels (Mandal and Mount, 2015). GLUT9 exists in two isoforms, GLUT9a and GLUT9b, which differ in their aminoterminal cytoplasmic domains; GLUT9a is located in the basolateral membrane, and GLUT9b is located in the apical membrane of the proximal tubules in human kidney (Augustin et al., 2004;Kimura et al., 2014). However, in mice, Glut9a is expressed in the proximal convoluted and straight tubules, and Glut9b is expressed in distal convoluted tubules and connecting tubules (Bibert et al., 2009). ...
... Human GLUT9a is 540 amino acids in length and is encoded by 12 exons, whereas GLUT9b is 511 amino acids in length and is encoded by 13 exons of the splice variants of RNA of the SLC2A9 gene. In both humans and mice, GLUT9b is expressed only in the liver and kidney, whereas GLUT9a is present in many more tissues, such as the liver, kidney, intestine, leukocytes, and chondrocytes (Augustin et al., 2004;Keembiyehetty et al., 2006;Kimura et al., 2014). ...
Hyperuricemia is the result of increased production and/or underexcretion of uric acid. Hyperuricemia has been epidemiologically associated with multiple comorbidities, including metabolic syndrome, gout with long-term systemic inflammation, chronic kidney disease, urolithiasis, cardiovascular disease, hypertension, rheumatoid arthritis, dyslipidemia, diabetes/insulin resistance and increased oxidative stress. Dysregulation of xanthine oxidoreductase (XOD), the enzyme that catalyzes uric acid biosynthesis primarily in the liver, and urate transporters that reabsorb urate in the renal proximal tubules (URAT1, GLUT9, OAT4 and OAT10) and secrete urate (ABCG2, OAT1, OAT3, NPT1, and NPT4) in the renal tubules and intestine, is a major cause of hyperuricemia, along with variations in the genes encoding these proteins. The first-line therapeutic drugs used to lower serum uric acid levels include XOD inhibitors that limit uric acid biosynthesis and uricosurics that decrease urate reabsorption in the renal proximal tubules and increase urate excretion into the urine and intestine via urate transporters. However, long-term use of high doses of these drugs induces acute kidney disease, chronic kidney disease and liver toxicity. Therefore, there is an urgent need for new nephroprotective drugs with improved safety profiles and tolerance. The current systematic review summarizes the characteristics of major urate transporters, the mechanisms underlying the pathogenesis of hyperuricemia, and the regulation of uric acid biosynthesis and transport. Most importantly, this review highlights the potential mechanisms of action of some naturally occurring bioactive compounds with antihyperuricemic and nephroprotective potential isolated from various medicinal plants.
... 9 Therefore, when SGLT2 is inhibited, the increased concentration of glucose within the lumen of the PCT competes with urate for GLUT9 isoform 2. 30 In addition to being found in the PCT, GLUT9 isoform 2 is also found in the collecting ducts, where it mediates urate reabsorption. 75 It has been found that an increased concentration of glucose in the lumen by SGLT2 inhibition also inhibits urate reabsorption mediated by GLUT9 isoform 2 found in the collecting ducts. 30 This uricosuric effect is also seen with phloridzin, a non-selective SGLT inhibitor, which induces uricosuria in healthy subjects. ...
Objectives:
Sodium-glucose cotransporter-2 (SGLT2) inhibitors have been found to reduce serum urate in patients with type 2 diabetes mellitus. To evaluate if this effect applies to both patients with and without diabetes, we conducted a systematic review and meta-analysis of SGLT2 inhibitors on serum urate levels in this population.
Methods:
Four electronic databases (PubMed, Embase, Cochrane and SCOPUS) were searched on 25 September 2021 for articles published from 1 January 2000 up to 25 September 2021, for studies that examined the effect of SGLT2 inhibitors on serum urate in study subjects. Random-effects meta-analysis was performed, with subgroup analyses on the type of SGLT2 inhibitor agent administered, presence of type 2 diabetes mellitus, presence of chronic kidney disease and drug dose.
Results:
A total of 43 randomized controlled trials, with a combined cohort of 31,921 patients, were included. Both patients with [−31.48 μmol/L; 95% confidence interval (CI): −37.35 to −25.60] and without diabetes (−91.38 μmol/L; 95% CI: −126.53 to −56.24) on SGLT2 inhibitors had significantly lower urate levels when compared with placebo. This treatment effect was similarly observed across different types of SGLT2 inhibitors. However, in type 2 diabetes mellitus (T2DM) patients with chronic kidney disease, the reduction in serum urate with SGLT2 inhibitors became insignificant (95% CI: −22.17 to 5.94, p < 0.01).
Conclusion:
This study demonstrated that SGLT2 inhibitors are beneficial in reducing serum urate in patients with and without diabetes. SGLT2 inhibitors could therefore contribute to the general treatment of hyperuricaemia.
