Molecular Mechanisms Underlying Urate-Induced Enhancement of Kv1.5 Channel Expression in HL-1 Atrial Myocytes
Molecular Mechanisms Underlying Urate-Induced Enhancement of Kv1.5 Channel Expression in HL-1 Atrial Myocytes
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DOI：
10.1253/circj.cj-15-0416
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发表时间：
2015-11-01
影响因子：
3.3
通讯作者：
Hisatome, Ichiro
中科院分区：
文献类型：
--
作者：
Maharani, Nani;Ting, Ya Kuang;Hisatome, Ichiro
背景：高尿酸血症诱导内皮功能障碍、氧化应激和炎症，增加心血管疾病的发病率。它还增加了心房颤动的发生率;然而，其潜在机制尚不清楚。方法和结果：采用逆转录酶-PCR、免疫印迹、流式细胞术和膜片钳实验研究了尿酸盐对培养的小鼠心房肌细胞（HL-1细胞）Kv1.5表达的影响。以7 mg/dl的尿酸盐处理HL-1细胞24 h，可增加Kv1.5蛋白水平，增强超快速延迟整流钾通道电流，缩短动作电位时程。HL-1细胞表达内流尿酸转运蛋白（UAT）URATv 1和外排UAT ABCG 2和MRP 4。对URATv 1的抑制剂，苯溴马隆，取消尿酸盐的影响，而对ABCG 2，KO 143的抑制剂，增强他们。流式细胞术显示尿酸盐诱导活性氧增加，抗氧化剂N-乙酰半胱氨酸（NAC）和NADPH氧化酶抑制剂夹竹桃苷可消除活性氧。NAC和夹竹桃麻素均能阻断尿酸盐对Kv1.5表达的增强作用。尿酸盐诱导的Kv1.5蛋白的增加伴随着细胞外信号调节激酶（ERK）的磷酸化，并通过ERK抑制剂PD 98059消除。结论：UATs摄取细胞内尿酸盐后，HL-1心房肌细胞Kv1.5蛋白表达增强，其机制可能与ERK磷酸化和NADPH氧化酶氧化应激有关。
Background: Hyperuricemia induces endothelial dysfunction, oxidative stress and inflammation, increasing cardiovascular morbidities. It also raises the incidence of atrial fibrillation; however, underlying mechanisms are unknown.Methods and Results: The effects of urate on expression of Kv1.5 in cultured mouse atrial myocytes (HL-1 cells) using reverse transcriptase-PCR, immunoblots, flow cytometry and patch-clamp experiments were studied. Treatment with urate at 7 mg/dl for 24 h increased the Kv1.5 protein level, enhanced ultra-rapid delayed-rectifier K+ channel currents and shortened action potential duration in HL-1 cells. HL-1 cells expressed the influx uric acid transporter (UAT), URATv1, and the efflux UATs, ABCG2 and MRP4. An inhibitor against URATv1, benzbromarone, abolished the urate effects, whereas an inhibitor against ABCG2, KO143, augmented them. Flow cytometry showed that urate induced an increase in reactive oxygen species, which was abolished by the antioxidant, N-acetylcysteine (NAC), and the NADPH-oxidase inhibitor, apocynin. Both NAC and apocynin abolished the enhancing effects of urate on Kv1.5 expression. A urate-induced increase in the Kv1.5 proteins was accompanied by phosphorylation of extracellular signal-regulated kinase (ERK), and was abolished by an ERK inhibitor, PD98059. NAC abolished phosphorylation of ERK by urate.Conclusions: Intracellular urate taken up by UATs enhanced Kv1.5 protein expression and function in HL-1 atrial myocytes, which could be attributable to ERK phosphorylation and oxidative stress derived from nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase.