The calcium release activated calcium (CRAC) channel is highly expressed in T lymphocytes and plays a critical role in regulating T cell proliferation and functions including activation of the transcription factor nuclear factor of activated T cells (NFAT), cytokine production and cytotoxicity. The CRAC channel consists of the Orai pore subunit and STIM (stromal interacting molecule) endoplasmic reticulum calcium sensor. Loss of CRAC channel mediated calcium signaling has been identified as an underlying cause of severe combined immunodeficiency (SCID), leading to drastically weakened immunity against infections. Gain-of-function mutations in Orai and STIM have been associated with tubular aggregated myopathy (TAM), a skeletal muscle disease. While a number of small molecules have shown activity in inhibiting the CRAC signaling pathway, the usefulness of those tool compounds is limited by their off-target activity against TRPM4 and TRPM7 ion channels, high lipophilicity, and a lack of understanding of their mechanism of action. We report structure-activity relationship (SAR) studies that resulted in the characterization of compound [1-(cyclopropylmethyl)-N-(3-fluoropyridin-4-yl)-1H-indazole-3-carboxamie] as a fast onset, reversible, and selective CRAC channel blocker. fully blocked the CRAC current (IC: 4.9 μM) and the nuclear translocation of NFAT at 30 and 10 μM, respectively, without affecting the electrophysiological function of TRPM4 and TRPM7 channels. Computational modeling appears to support its direction binding to Orai proteins that form the transmembrane CRACchannel.

中文翻译：

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发现带有吲唑或吡唑支架的选择性 Orai 通道阻断剂


钙释放激活钙 (CRAC) 通道在 T 淋巴细胞中高表达，在调节 T 细胞增殖和功能（包括活化 T 细胞转录因子核因子 (NFAT) 的激活、细胞因子的产生和细胞毒性）中发挥着关键作用。 CRAC 通道由 Orai 孔亚基和 STIM（基质相互作用分子）内质网钙传感器组成。 CRAC 通道介导的钙信号传导丧失已被确定为严重联合免疫缺陷 (SCID) 的根本原因，导致抵抗感染的免疫力急剧下降。 Orai 和 STIM 的功能获得突变与管状聚集性肌病 (TAM)（一种骨骼肌疾病）有关。虽然许多小分子已显示出抑制 CRAC 信号通路的活性，但这些工具化合物的用途受到其针对 TRPM4 和 TRPM7 离子通道的脱靶活性、高亲脂性以及对其作用机制缺乏了解的限制。 。我们报告了构效关系 (SAR) 研究，将化合物 [1-(环丙基甲基)-N-(3-氟吡啶-4-基)-1H-吲唑-3-羧酰胺] 表征为一种快速起效、可逆的药物，以及选择性 CRAC 通道阻断剂。分别在30和10μM时完全阻断CRAC电流（IC：4.9μM）和NFAT的核转位，而不影响TRPM4和TRPM7通道的电生理功能。计算模型似乎支持其与形成跨膜 CRAC 通道的 Orai 蛋白结合的方向。