Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in genes encoding the polycystin (PC) 1 and 2 proteins. The goal of this study was to determine the role of calcium in regulating cyst growth. Stromal interaction molecule 1 (STIM1) protein expression was 15-fold higher in PC1-null proximal tubule cells (PN) than in heterozygote (PH) controls and 2-fold higher in an inducible, PC1 knockout, mouse model of ADPKD compared to a non-cystic match control. IP3 receptor protein expression was also higher in the cystic mice. Knocking down STIM1 with siRNA reduced cyst growth and lowered cAMP levels in PN cells. Fura2 measurements of intracellular Ca2+ showed higher levels of intracellular Ca2+, SOCE and thaspigargin-stimulated ER Ca2+ release in PN vs. PH cells. There was a dramatic reduction in thapsigargin-stimulated release of ER Ca2+ following STIM1 silencing or application of 2-APB, consistent with altered ER Ca2+ movement; the protein expression of the Ca2+-dependent adenylyl cyclases (AC) AC3 and AC6 was up- and down-regulated, respectively. Like STIM1 knockdown, application of the calmodulin inhibitor W7 lowered cAMP levels, further indicating that STIM1 regulates AC3 via Ca2+ We conclude that the high levels of STIM1 in ADPKD cells play a role in supporting cyst growth and promoting high cAMP levels and an increased release of Ca2+ from the ER. Thus, our results provide novel therapeutic targets for treating ADPKD.

中文翻译：

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钙在成人多囊肾病中的作用。

常染色体显性多囊肾病 (ADPKD) 是由编码多囊蛋白 (PC) 1 和 2 蛋白的基因突变引起的。本研究的目的是确定钙在调节囊肿生长中的作用。基质相互作用分子 1 (STIM1) 蛋白表达在 PC1 缺失的近曲小管细胞 (PN) 中比在杂合子 (PH) 对照中高 15 倍，在可诱导的 PC1 敲除 ADPKD 小鼠模型中比在杂合子 (PH) 对照中高 2 倍。非囊性匹配控制。IP3受体蛋白表达在囊性小鼠中也较高。用 siRNA 敲除 STIM1 可减少 PN 细胞中的囊肿生长并降低 cAMP 水平。Fura2 细胞内 Ca2+ 测量显示，与 PH 细胞相比，PN 细胞中细胞内 Ca2+、SOCE 和 thaspigargin 刺激的 ER Ca2+ 释放水平更高。STIM1 沉默或应用 2-APB 后，毒胡萝卜素刺激的 ER Ca2+ 释放显着减少，这与 ER Ca2+ 运动的改变一致；Ca2+依赖性腺苷酸环化酶（AC）AC3和AC6的蛋白表达分别上调和下调。与 STIM1 敲低一样，钙调蛋白抑制剂 W7 的应用降低了 cAMP 水平，进一步表明 STIM1 通过 Ca2+ 调节 AC3 我们得出结论，ADPKD 细胞中高水平的 STIM1 在支持囊肿生长和促进高 cAMP 水平以及增加释放来自急诊室的 Ca2+。因此，我们的结果为治疗 ADPKD 提供了新的治疗靶点。