URAT1 inhibition by ALPK1 is associated with uric acid homeostasis.

OBJECTIVE: The aim of this study was to identify a protein for urate transporter 1 (URAT1) regulation.

METHODS: The clinical dataset consisted of 492 case-control samples of Han Chinese (104 gout and 388 controls). Three alpha kinase 1 ( ALPK1 ) and SLC22A12 loci associated with high gout risk and uric acid levels were genotyped. The overexpression of ALPK1 on URAT1 protein expression was evaluated in vivo in h ALPK1 transgenic mice. The in vitro protein levels of ALPK1 and URAT1 in ALPK1 small interfering RNA-transfected human kidney-2 cells with MSU crystal stimulation were examined.

RESULTS: ALPK1 , which is a single nucleotide polymorphism (SNP) of rs11726117 (M861T; T), reduced the risk of gout via the SLC22A12 gene SNPs rs3825016 and rs475688, as compared with the subject of ALPK1 rs11726117 (C) allele {rs11726117 [CT + TT] vs rs3825016, odds ratio [OR] 0.39 [95% confidence interval (CI) 0.23, 0.67]; rs11726117 [CT + TT] vs rs475688, OR 0.39 [95% CI 0.23, 0.67]}. ALPK1-overexpressed mice demonstrated lower levels of URAT1 protein ( P = 0.0045). Mouse endogenous ALPK1 proteins were detected in renal proximal tubule cells. MSU crystals inhibited URAT1 expressions through an upregulation of ALPK1 in human kidney-2 cells.

CONCLUSION: Elevated ALPK1 expression decreased URAT1 expression. ALPK1 might prevent the impact of urate reuptake via SLC22A12 and appeared to be negatively associated with gout. ALPK1 is a potential repressor of URAT1 protein expression.