Inhibition of Sodium Glucose Cotransporter 2 Attenuates the Dysregulation of Kelch-Like 3 and NaCl Cotransporter in Obese Diabetic Mice
Inhibition of Sodium Glucose Cotransporter 2 Attenuates the Dysregulation of Kelch-Like 3 and NaCl Cotransporter in Obese Diabetic Mice
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DOI：
10.1681/asn.2018070703
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发表时间：
2019-05-01
影响因子：
13.6
通讯作者：
Shibata, Shigeru
中科院分区：
文献类型：
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作者：
Ishizawa, Kenichi;Wang, Qin;Shibata, Shigeru
背景 盐敏感性高血压和 2 型糖尿病之间频繁关联的机制仍不清楚。我们之前发现蛋白激酶 C (PKC) 激活会使 Kelch-like 3 (KLHL3)（一种 E3 泛素连接酶成分）在丝氨酸 433 处磷酸化。我们研究了 KLHL3 活性受损是否会通过 NaCl 协同转运蛋白 (NCC) 增加肾盐重吸收。方法我们使用 db/db 糖尿病小鼠模型来探索 KLHL3 在 2 型糖尿病肾盐处理中的作用，并评估 KLHL3 失调的机制结果 我们观察到 db/db 小鼠肾脏中的 PKC 活性以及 KLHL3 (KLHL3(S433-P)) 中丝氨酸 433 的磷酸化。这种修饰可防止与无赖氨酸 (WNK) 激酶的结合；然而，总 KLHL3 水平下降，表明 KLHL3 活性严重受损。这导致 WNK 积聚，激活远曲小管中的 NCC。 Ipragliflozin 是一种钠葡萄糖协同转运蛋白 2 (SGLT2) 抑制剂，可降低远曲小管细胞中的 PKC 活性，并降低 KLHL3(S433-P) 和 NCC 水平，而噻唑烷二酮吡格列酮则不然，尽管这两种药物同样降低了血糖水平。我们发现，在表达 KLHL3 的人胚胎肾细胞和远曲小管细胞中，细胞葡萄糖积累通过 PKC 增加了 KLHL3(S433-P) 水平。最后，在db/db小鼠肾脏中抑制PKC的作用证实了PKC在KLHL3(S433-P)和NCC诱导中的因果作用。结论KLHL3的失调与2型糖尿病的病理生理学有关。这些数据为糖尿病患者使用噻嗪类药物提供了理论依据，并深入了解了 SGLT2 抑制剂的心肾保护作用机制。
Background Mechanisms underlying the frequent association between salt-sensitive hypertension and type 2 diabetes remain obscure. We previously found that protein kinase C (PKC) activation phosphorylates Kelch-like 3 (KLHL3), an E3 ubiquitin ligase component, at serine 433. We investigated whether impaired KLHL3 activity results in increased renal salt reabsorption via NaCl cotransporter (NCC).Methods We used the db/db diabetes mouse model to explore KLHL3s role in renal salt handling in type 2 diabetes and evaluated mechanisms of KLHL3 dysregulation in cultured cells.Results We observed PKC activity in the db/db mouse kidney and phosphorylation of serine 433 in KLHL3 (KLHL3(S433-P)). This modification prevents binding of with-no-lysine (WNK) kinases; however, total KLHL3 levels were decreased, indicating severely impaired KLHL3 activity. This resulted in WNK accumulation, activating NCC in distal convoluted tubules. Ipragliflozin, a sodium glucose cotransporter 2 (SGLT2) inhibitor, lowered PKC activity in distal convoluted tubule cells and reduced KLHL3(S433-P) and NCC levels, whereas the thiazolidinedione pioglitazone did not, although the two agents similarly reduced in blood glucose levels. We found that, in human embryonic kidney cells expressing KLHL3 and distal convoluted tubule cells, cellular glucose accumulation increased KLHL3(S433-P) levels through PKC. Finally, the effect of PKC inhibition in the kidney of db/db mice confirmed PKC's causal role in KLHL3(S433-P) and NCC induction.Conclusions Dysregulation of KLHL3 is involved in the pathophysiology of type 2 diabetes. These data offer a rationale for use of thiazide in individuals with diabetes and provide insights into the mechanism for cardiorenal protective effects of SGLT2 inhibitors.