Development of a Chemical Probe to Enable Characterization of the Casein Kinase 1γ Subfamily

The casein kinase 1γ (CK1γ) subfamily, while severely understudied, is implicated in diverse disease–relevant pathways, including WNT signaling and human cytomegalovirus (HCMV) replication. While genetic tools exist to study CK1γ, the selective inhibition of CK1γ through pharmacological means remains underexplored. Chemical probes, or potent and selective inhibitors, remain one of the most powerful pharmacological tools for uncovering protein biology. Herein, we developed several novel assays for assessing target engagement with the CK1γ subfamily in cells. Enabled by these assays, we conducted a comprehensive structure–activity relationship (SAR) campaign to develop the first chemical probe, SGC-CK1γ-1, for the CK1γ subfamily. SGC-CK1γ-1, which was developed alongside a structurally related negative control compound, potently and selectively inhibited the CK1γ kinases in living cells, plus inhibited both WNT signaling and human cytomegalovirus replication.酪蛋白激酶1γ（casein kinase 1γ, CK1γ）亚家族尽管研究严重匮乏，但已被证实参与多种与疾病相关的通路，包括WNT信号通路（WNT signaling）以及人类巨细胞病毒（human cytomegalovirus, HCMV）的复制过程。尽管已有遗传工具可用于CK1γ的相关研究，但通过药理学手段实现CK1γ的选择性抑制仍未得到充分探索。化学探针，即强效选择性抑制剂，仍是揭示蛋白质生物学功能的最强大药理学工具之一。本研究中，我们开发了数种全新的检测方法，用于评估细胞内CK1γ亚家族的靶点结合情况。依托上述检测方法，我们开展了全面的构效关系（structure–activity relationship, SAR）研究，成功开发出首个针对CK1γ亚家族的化学探针SGC-CK1γ-1。SGC-CK1γ-1与一款结构相关的阴性对照化合物联合研发而成，可在活细胞中强效且选择性地抑制CK1γ激酶家族，并同时抑制WNT信号通路与人类巨细胞病毒的复制过程。