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The Calcium-Sensing Receptor Increases Activity of the Renal NCC through the WNK4-SPAK Pathway
Journal of the American Society of Nephrology ( IF 13.6 ) Pub Date : 2018-07-01 , DOI: 10.1681/asn.2017111155
Silvana Bazúa-Valenti , Lorena Rojas-Vega , María Castañeda-Bueno , Jonatan Barrera-Chimal , Rocío Bautista , Luz G. Cervantes-Pérez , Norma Vázquez , Consuelo Plata , Adrián R. Murillo-de-Ozores , Lorenza González-Mariscal , David H. Ellison , Daniela Riccardi , Norma A. Bobadilla , Gerardo Gamba

Background Hypercalciuria can result from activation of the basolateral calcium-sensing receptor (CaSR), which in the thick ascending limb of Henle’s loop controls Ca2+ excretion and NaCl reabsorption in response to extracellular Ca2+. However, the function of CaSR in the regulation of NaCl reabsorption in the distal convoluted tubule (DCT) is unknown. We hypothesized that CaSR in this location is involved in activating the thiazide-sensitive NaCl cotransporter (NCC) to prevent NaCl loss.

Methods We used a combination of in vitro and in vivo models to examine the effects of CaSR on NCC activity. Because the KLHL3-WNK4-SPAK pathway is involved in regulating NaCl reabsorption in the DCT, we assessed the involvement of this pathway as well.

Results Thiazide-sensitive 22Na+ uptake assays in Xenopus laevis oocytes revealed that NCC activity increased in a WNK4-dependent manner upon activation of CaSR with Gd3+. In HEK293 cells, treatment with the calcimimetic R-568 stimulated SPAK phosphorylation only in the presence of WNK4. The WNK4 inhibitor WNK463 also prevented this effect. Furthermore, CaSR activation in HEK293 cells led to phosphorylation of KLHL3 and WNK4 and increased WNK4 abundance and activity. Finally, acute oral administration of R-568 in mice led to the phosphorylation of NCC.

Conclusions Activation of CaSR can increase NCC activity via the WNK4-SPAK pathway. It is possible that activation of CaSR by Ca2+ in the apical membrane of the DCT increases NaCl reabsorption by NCC, with the consequent, well known decrease of Ca2+ reabsorption, further promoting hypercalciuria.



中文翻译:

钙敏感受体通过WNK4-SPAK途径增加肾NCC的活性

背景高钙尿症可能是由基底外侧钙敏感受体(CaSR)激活引起的,该受体在Henle环的厚上升肢中控制Ca 2+的排泄和响应细胞外Ca 2+的NaCl重吸收。但是,CaSR在远端回旋小管(DCT)中调节NaCl重吸收的功能尚不清楚。我们假设该位置的CaSR参与激活噻嗪类敏感的NaCl共转运蛋白(NCC),以防止NaCl丢失。

方法我们使用体外体内模型相结合的方法来研究CaSR对NCC活性的影响。因为KLHL3-WNK4-SPAK通路参与调节DCT中NaCl的重吸收,所以我们也评估了该通路的参与。

结果非洲爪蟾卵母细胞对噻嗪类药物敏感的22 Na +吸收试验表明,随着Gd 3+激活CaSR,NCC活性以WNK4依赖性方式增加。在HEK293细胞中,仅在WNK4存在下,用拟钙剂R-568处理可刺激SPAK磷酸化。WNK4抑制剂WNK463也阻止了这种作用。此外,HEK293细胞中的CaSR激活导致KLHL3和WNK4磷酸化并增加WNK4的丰度和活性。最后,在小鼠中急性口服R-568导致NCC磷酸化。

结论CaSR的激活可以通过WNK4-SPAK途径增加NCC的活性。DCT根尖膜中Ca 2+对CaSR的激活可能会增加NCC对NaCl的重吸收,从而导致众所周知的Ca 2+重吸收减少,从而进一步促进高钙血症。

更新日期:2018-06-30
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