Astrocytes are non-excitable cells in the brain and their activity largely depends on the intracellular calcium (Ca²⁺) level. Therefore, maintaining the intracellular Ca²⁺ homeostasis is critical for proper functioning of astrocytes. One of the key regulatory mechanisms of Ca²⁺ homeostasis in astrocytes is the store-operated Ca²⁺ entry (SOCE). This process is mediated by a combination of the Ca²⁺-store-depletion-sensor, Stim, and the store-operated Ca²⁺-channels, Orai and TrpC families. Despite the existence of all those families in astrocytes, previous studies have provided conflicting results on the molecular identification of astrocytic SOCE. Here, using the shRNA-based gene-silencing approach and Ca²⁺-imaging from cultured mouse astrocytes, we report that Stim1 in combination with Orai1 and Orai3 contribute to the major portion of astrocytic SOCE. Gene-silencing of Stim1 showed a 79.2% reduction of SOCE, indicating that Stim1 is the major Ca²⁺-store-depletion-sensor. Further gene-silencing showed that Orai1, Orai2, Orai3, and TrpC1 contribute to SOCE by 35.7%, 20.3%, 26.8% and 12.2%, respectively. Simultaneous gene-silencing of all three Orai subtypes exhibited a 67.6% reduction of SOCE. Based on the detailed population analysis, we predict that Orai1 and Orai3 are expressed in astrocytes with a large SOCE, whereas TrpC1 is exclusively expressed in astrocytes with a small SOCE. This analytical approach allows us to identify the store operated channel (SOC) subtype in each cell by the degree of SOCE. Our results propose that Stim1 in combination with Orai1 and Orai3 are the major molecular components of astrocytic SOCE under various physiological and pathological conditions.

中文翻译：

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Orai1和Orai3与Stim1的组合介导星形胶质细胞的钙存储钙输入的大多数。

星形胶质细胞是大脑中不可激发的细胞，其活性很大程度上取决于细胞内钙（Ca ²⁺）的水平。因此，维持细胞内Ca ²⁺稳态对于星形胶质细胞的正常运转至关重要。星形胶质细胞中Ca ²⁺稳态的关键调控机制之一是储存操纵的Ca ²⁺进入（SOCE）。此过程是由Ca 2 ⁺ -商店耗竭传感器，Stim和商店经营的Ca ²⁺的组合介导的频道，Orai和TrpC系列。尽管星形胶质细胞中存在所有这些家族，但先前的研究在星形细胞SOCE的分子鉴定中提供了相互矛盾的结果。在这里，我们使用基于shRNA的基因沉默方法和来自培养的小鼠星形胶质细胞的Ca ²⁺成像，我们报道Stim1与Orai1和Orai3的结合构成了星形细胞SOCE的主要部分。Stim1的基因沉默显示SOCE降低79.2％，表明Stim1是主要的Ca ²⁺存储耗尽传感器。进一步的基因沉默显示，Orai1，Orai2，Orai3和TrpC1对SOCE的贡献分别为35.7％，20.3％，26.8％和12.2％。所有三个Orai亚型的同时基因沉默表现出SOCE降低67.6％。根据详细的人口分析，我们预测Orai1和Orai3在具有较大SOCE的星形胶质细胞中表达，而TrpC1仅在具有较小SOCE的星形胶质细胞中表达。这种分析方法使我们能够通过SOCE的程度来识别每个单元中的存储操作通道（SOC）子类型。我们的研究结果表明，在各种生理和病理条件下，Stim1与Orai1和Orai3的结合是星形细胞SOCE的主要分子成分。