Gene-environment interaction modifies the association between hyperinsulinemia and serum urate levels through SLC22A12
Wataru Fujii, … , Yuta Kochi, Shigeru Shibata
Wataru Fujii, … , Yuta Kochi, Shigeru Shibata
Published March 18, 2025
Citation Information: J Clin Invest. 2025;135(10):e186633. https://doi.org/10.1172/JCI186633.
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Clinical Research and Public Health Genetics Metabolism Nephrology

Gene-environment interaction modifies the association between hyperinsulinemia and serum urate levels through SLC22A12

Abstract

BACKGROUND Hyperinsulinemia and insulin resistance often accompany elevated serum urate levels (hyperuricemia), a highly heritable condition that triggers gout; however, the underlying mechanisms are unclear.METHODS We evaluated the association between the index of hyperinsulinemia and the fractional excretion of urate (FEUA) in 162 outpatients. The underlying mechanisms were investigated through single-cell data analysis and kinase screening combined with cell culture experiments. In 377,358 participants of the UK Biobank (UKBB), we analyzed serum urate, hyperinsulinemia, and salt intake. We also examined gene-environment interactions using single nucleotide variants in SLC22A12, which encodes urate transporter 1 (URAT1).RESULTS The index of hyperinsulinemia was inversely associated with FEUA independently of other covariates. Mechanistically, URAT1 cell-surface abundance and urate transport activity were regulated by URAT1-Thr408 phosphorylation, which was stimulated by hyperinsulinemia via AKT. Kinase screening and single-cell data analysis revealed that serum and glucocorticoid-regulated kinase 1 (SGK1), induced by high salt, activated the same pathway, increasing URAT1. Arg405 was essential for these kinases to phosphorylate URAT1-Thr408. In UKBB participants, hyperinsulinemia and high salt intake were independently associated with increased serum urate levels. We found that SLC22A12 expression quantitative trait locus (eQTL) rs475688 synergistically enhanced the positive association between serum urate and hyperinsulinemia.CONCLUSION URAT1 mediates the association between hyperinsulinemia and hyperuricemia. Our data provide evidence for the role of gene-environment interactions in determining serum urate levels, paving the way for personalized management of hyperuricemia.FUNDING ACRO Research Grants of Teikyo University; Japan Society for the Promotion of Science; the Japanese Society of Gout and Uric & Nucleic Acids; Fuji Yakuhin; Nanken-Kyoten; Medical Research Center Initiative for High Depth Omics.

Authors

Wataru Fujii, Osamu Yamazaki, Daigoro Hirohama, Ken Kaseda, Emiko Kuribayashi-Okuma, Motonori Tsuji, Makoto Hosoyamada, Yuta Kochi, Shigeru Shibata

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Figure 1

T408 phosphorylation regulates URAT1 trafficking and urate transport activity.

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T408 phosphorylation regulates URAT1 trafficking and urate transport act...
(A) Flag-tagged, hURAT1 was expressed in HEK293 cells, incubated in the presence or absence of insulin (100 nM for 3 hours), and purified by Flag-IP. Samples were subjected to Western blotting with anti–R-x-x-SP/TP and anti-Flag antibodies. (B) Candidate phosphorylation sites and alignment among orthologs. (C) Location of T350 and T408 in the 3D modeled structure of URAT1. (D) WT or nonphosphorylatable T305A/T408A Flag-URAT1 was expressed in HEK cells, purified by IP, and incubated with AKT1 in the presence of ATP. Phosphorylation signal was detected by ADP-glo assay (n = 3). (E) WT hURAT1 (hURAT1WT) and hURAT1 carrying nonphosphorylatable T350A (hURAT1T350A) and T408A substitution (hURAT1T408A) were expressed in HEK cells. Cell-surface levels were analyzed by cell-surface biotinylation assay. Bar graphs show the results of quantitation from 4 independent experiments. (F) Uptake of 10 μM [14C]urate was measured in HEK cells expressing no URAT1 (control), HEK cells expressing hURAT1WT, and those expressing hURAT1T408A (n = 3). (G) HEK cells expressing Flag-hURAT1WT and Flag-hURAT1T408A were stained with anti-Flag antibody (green) and DAPI (blue). hURAT1WT is predominantly expressed at or near plasma membrane, whereas hURAT1T408A is cytoplasmic. Scale bars: 10 μm. (H) Time course analysis of hURAT1 glycosylation. HEK cells expressing WT or indicated nonphosphorylatable forms of hURAT1 were lysed and analyzed by Western blotting at 24, 48, and 72 hours. Bars graphs show the results of quantitation of fully glycosylated form versus core glycosylated form (n = 6). (I) Comparison of hURAT1 glycosylation between WT hURAT1 and nonsynonymous single-nucleotide variant (rs146048999; hURAT1 with T408M substitution). Data are represented as mean ± SEM. (D) Unpaired t test; (E, F, H, and I) 1-way ANOVA with Dunnett’s test. *P < 0.05; **P < 0.01; ***P < 0.001.