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We investigated the interactions of ALPK1 variants and the loci of ABCG2, SLC2A9, and SLC22A12 on gout risk. We conducted two case-control studies. Participants were recruited from hospitals (n = 410; 104 gout cases and 306 controls) and communities (n = 678; 373 gout cases and 305 controls) in Taiwan. The genotypes of ALPK1 (rs11726117 M861T, rs231247 R1084R, and rs231253 3' UTR), ABCG2 (rs2231142 Q141K and rs2231137 V12M), SLC2A9 (rs3733591 R265H and rs1014290), and SLC22A12 (rs3825016 H86H, rs11231825 H142H, and rs475688) were genotyped. Under a recessive model, the joint effects of ALPK1 variants and the SNPs rs2231142 of ABCG2, rs1014290 of SLC2A9, or rs475688 and rs3825016 of SLC22A12 were associated with gout. The rs11726117 [CC] of ALPK1 and rs2231142 [TT] of ABCG2 with the sequential addition of the rs1014290 [AA] of SLC2A9 and rs3825016 [CC] of SLC22A12 were associated with gout risk (odds ratio (OR): 13.01, 15.11, and 55.00 and positive predictive value (PPV): 56%, 69%, and 99% in the Han group, respectively; OR: 3.76, 5.78, and 12.30 and PPV: 74%, 80%, and 81% in the aboriginal group, respectively). Combined exposure to the four high-risk genotypes of ALPK1 and the uric-acid-related loci of ABCG2, SLC2A9, and SLC22A12 was associated with an increased gout risk and a high PPV for gout.

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., (© The Author 2016. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com)

Alpha-protein kinase 1, also known as alpha-kinase 1 (ALPK1), is associated with chronic kidney disease (CKD), myocardial infarction, gout and type 2 diabetes mellitus (DM). In addition to having an inductive effect on the proinflammatory cytokines in monocytic THP1 cells, ALPK1 is expressed abundantly in the mouse testes. Low testosterone levels are commonly associated with arthritis, CKD, type 2 DM, cardiovascular disease and inflammation. The testosterone's anti-inflammatory effect has been demonstrated to reduce proinflammatory cytokines and adhesion molecules. In this study, we found that ALPK1 transgenic mice showed lower levels of testosterone in both the testes and the serum. Decreasing endogenous ALPK1 enhanced testosterone levels and transcripts of testosterone-regulated genes (P450scc, 3beta-HSD, P450C17, 17beta-HSD, StAR, and INSL3) in TM3 Leydig cells. In contrast, increasing testosterone decreased ALPK1 in both TM3 and monocytic THP1 cells. This decrease was accompanied by a reduction of the proinflammatory cytokines. Increased ALPK1 levels attenuated the testosterone effects in THP1 cells. Finally, we also found that ALPK1 increased the release of TNF-alpha and TGF-beta1 in the human embryonic kidney 293 cells, while testosterone inhibited ALPK1 in the primary kidney cells. Taken together, this data suggests that the balance between ALPK1 and testosterone plays a critical role in the testosterone-mediated inhibition of proinflammatory cytokines., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: The present study investigated whether single nucleotide polymorphisms (SNPs) in the alpha-protein kinase 1 (ALPK1) gene are associated with gout in aboriginal and Han Chinese Taiwanese., Methods: A total of 1351 aborigines from the community (511 cases and 840 controls) and 511 Han people from hospital (104 cases and 407 controls) were recruited. SNPs in potentially functional regions of the 38 genes within 4q25 were identified and genotypes determined by direct sequencing. Quantitation of blood ALPK1 mRNA expression levels and luciferase assay of gout-associated rs231253 pGL3-SNP constructs cotransfected with hsa-miR-519e were examined., Results: We found that ALPK1 gene was the most determinant of gout. Three SNPs of rs11726117 M861T [C], rs231247 [G] and rs231253 [G] were most associated with gout risk [odd ratios (OR) ≥1.44, P ≤ 3.78 × 10(-6)) in aborigines. A replication set using Han people had risk at rs11726117 and rs231247 (OR ≥1.72, P ≤ 4.08 × 10(-3)). From pooled analysis (Breslow-Day test, P > 0.33) assuming an additive model, each increasing copy of the risk allele of rs11726117 [C], rs231247 [G] and rs231253 [G] showed significantly elevated OR for gout ≥1.42 (P ≥ 1.53 × 10(-6)). Consistently, the composite homozygous of linked 3 SNPs (versus wild-type, OR = 1.83, P = 8.21 × 10(-4)) had strong associations with ALPK1 mRNA expression. Luciferase showed reduced hybridization between hsa-miR-519e and construct carrying gout-associated rs231253 [G] than the wild-type [C] (P = 6.19 × 10(-4))., Conclusions: Our study found that a newly identified ALPK1 gene can effectively interfere with microRNA target recognition and modulates the mRNA expression; and the varying distribution of the implicated SNPs among cases and controls in the two studied populations suggests a significant role in gout susceptibility.

The molecular functions and pathophysiologic role of the lymphocyte α-kinase gene (ALPK1) in gout are unknown. We aimed to examine ALPK1 expression in patients with gout and investigate its role in monosodium urate monohydrate (MSU)-induced inflammatory responses. Microarray data mining was performed with six datasets containing three clinical gout and three volunteer samples. Real-time quantitative polymerase chain reaction (qPCR) assay was used to profile ALPK1 mRNA expression in 62 independent samples. RNA interference for ALPK1 suppression in THP1 cells (human monocytic cell line) was used to scrutinize the functional role of ALPK1 in MSU-mediated inflammatory responses, and ALPK1 expression in MSU-treated THP1 cells was determined by qPCR and Western blot analysis. Cytokine mRNA expression in HEK293 cells after incubation with different concentrations of MSU crystals in the presence or absence of ALPK1 was also detected by qPCR, and ERK1/2, p38, and JNK expressions were investigated by Western blot analysis. ALPK1 mRNA was overexpressed in the clinical gout samples. MSU treatment promoted ALPK1 expression at the mRNA and protein levels. Furthermore, ALPK1 knockdown in THP1 cells resulted in a markedly decreased IL-1β, TNF-α, and IL-8 mRNA expression; plasmid ALPK1 transfection and MSU stimulation synergistically increased the mRNA expression of these cytokines in a concentration-dependent manner. The synergistic effect also led to ERK1/2 activation. ALPK1 is a gout-susceptible gene involved in MSU-induced inflammatory responses. It may contribute to the development of gout by enhancing the inflammatory responses via the mitogen-activated protein kinase pathway.

Background The present study investigated whether single nucleotide polymorphisms (SNPs) in the alpha-protein kinase 1 (ALPK1) gene are associated with gout in aboriginal and Han Chinese Taiwanese.Methods A total of 1351 aborigines from the community (511 cases and 840 controls) and 511 Han people from hospital (104 cases and 407 controls) were recruited. SNPs in potentially functional regions of the 38 genes within 4q25 were identified and genotypes determined by direct sequencing. Quantitation of blood ALPK1 mRNA expression levels and luciferase assay of gout-associated rs231253 pGL3-SNP constructs cotransfected with hsa-miR-519e were examined.Results We found that ALPK1 gene was the most determinant of gout. Three SNPs of rs11726117 M861T [C], rs231247 [G] and rs231253 [G] were most associated with gout risk [odd ratios (OR) ≥1.44, P ≤ 3.78 × 10−6) in aborigines. A replication set using Han people had risk at rs11726117 and rs231247 (OR ≥1.72, P ≤ 4.08 × 10−3). From pooled analysis (Breslow-Day test, P > 0.33) assuming an additive model, each increasing copy of the risk allele of rs11726117 [C], rs231247 [G] and rs231253 [G] showed significantly elevated OR for gout ≥1.42 (P ≥ 1.53 × 10−6). Consistently, the composite homozygous of linked 3 SNPs (versus wild-type, OR = 1.83, P = 8.21 × 10−4) had strong associations with ALPK1 mRNA expression. Luciferase showed reduced hybridization between hsa-miR-519e and construct carrying gout-associated rs231253 [G] than the wild-type [C] (P = 6.19 × 10−4).Conclusions Our study found that a newly identified ALPK1 gene can effectively interfere with microRNA target recognition and modulates the mRNA expression; and the varying distribution of the implicated SNPs among cases and controls in the two studied populations suggests a significant role in gout susceptibility. [ABSTRACT FROM AUTHOR]