Heterologous expression of polycystin-1 inhibits endoplasmic reticulum calcium leak in stably transfected MDCK cells.
Heterologous expression of polycystin-1 inhibits endoplasmic reticulum calcium leak in stably transfected MDCK cells.
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DOI：
10.1152/ajprenal.00348.2007
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发表时间：
2008-06
期刊：
影响因子：
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通讯作者：
K. Weber;E. K. Lee;U. Basavanna;S. Lindley;R. Ziegelstein;G. Germino;M. Sutters
中科院分区：
文献类型：
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作者：
K. Weber;E. K. Lee;U. Basavanna;S. Lindley;R. Ziegelstein;G. Germino;M. Sutters
我们先前发现，多囊蛋白-1通过增强钙重摄取进入内质网而加速配体激活的细胞质钙瞬变的衰减（ER; Hooper KM，Boletta A，Germino GG，Hu Q，Ziegelstein RC，Sutters M. Am J Physiol Renal Physiol 289：F521-F530，2005）。通过ER膜的钙通量由主动摄取和被动泄漏的平衡决定。在本研究中，我们表明，多囊蛋白-1抑制钙泄漏的ER膜，这种效果将解释这种蛋白质的能力，以加速清除钙从细胞质后的钙释放反应。通过测量用毒胡萝卜素处理后细胞质中钙的积累来检测钙渗漏。在Madin-Darby犬肾细胞中稳定表达的异源多囊蛋白-1减弱了毒胡萝卜素诱导的钙峰，对基础钙储存、线粒体钙摄取或钙跨质膜挤出没有影响。使用钙离子载体离子霉素间接显示了多囊蛋白-1在抑制泵后限制ER管腔钙衰减速率的能力，并通过用低亲和力钙指示剂加载ER直接显示。我们的结论是，破坏内质网腔钙稳态可能有助于囊肿表型的常染色体显性遗传性多囊肾病。
We previously found that polycystin-1 accelerated the decay of ligand-activated cytoplasmic calcium transients through enhanced reuptake of calcium into the endoplasmic reticulum (ER; Hooper KM, Boletta A, Germino GG, Hu Q, Ziegelstein RC, Sutters M. Am J Physiol Renal Physiol 289: F521-F530, 2005). Calcium flux across the ER membrane is determined by the balance of active uptake and passive leak. In the present study, we show that polycystin-1 inhibited calcium leak across the ER membrane, an effect that would explain the capacity of this protein to accelerate clearance of calcium from the cytoplasm following a calcium release response. Calcium leak was detected by measurement of the accumulation of calcium in the cytoplasm following treatment with thapsigargin. Heterologous polycystin-1, stably expressed in Madin-Darby canine kidney cells, attenuated the thapsigargin-induced calcium peak with no effect on basal calcium stores, mitochondrial calcium uptake, or extrusion of calcium across the plasma membrane. The capacity of polycystin-1 to limit the rate of decay of ER luminal calcium following inhibition of the pump was shown indirectly using the calcium ionophore ionomycin, and directly by loading the ER with a low-affinity calcium indicator. We conclude that disruption of ER luminal calcium homeostasis may contribute to the cyst phenotype in autosomal dominant polycystic kidney disease.