Rapid and specific degradation of endogenous proteins in mouse models using auxin-inducible degrons

Auxin-inducible degrons are a chemical genetic tool for targeted protein
degradation and are widely used to study protein function in cultured
mammalian cells. Here we develop CRISPR-engineered mouse lines that enable
rapid and highly specific degradation of tagged endogenous proteins in
vivo. Most but not all cell types are competent for degradation. By
combining ligand titrations with genetic crosses to generate animals with
different allelic combinations, we show that degradation kinetics depend
upon the dose of the tagged protein, ligand, and the E3 ligase substrate
receptor TIR1. Rapid degradation of condensin I and condensin II – two
essential regulators of mitotic chromosome structure - revealed that both
complexes are individually required for cell division in precursor
lymphocytes, but not in their differentiated peripheral lymphocyte
derivatives. This generalisable approach provides unprecedented temporal
control over the dose of endogenous proteins in mouse models, with
implications for studying essential biological pathways and modeling drug
activity in mammalian tissues.

生长素诱导降解标签（Auxin-inducible degrons）是一类用于靶向蛋白质降解的化学遗传学工具，已被广泛应用于培养哺乳动物细胞的蛋白质功能研究。本研究构建了经CRISPR编辑的小鼠品系，可在活体中实现对带有标签的内源蛋白质的快速且高度特异性降解。多数而非全部细胞类型具备降解能力。本研究通过将配体滴定实验与遗传杂交相结合，以获得携带不同等位基因组合的实验动物，结果表明降解动力学取决于靶标标签蛋白、配体以及E3泛素连接酶（E3 ligase）底物受体TIR1的剂量。对有丝分裂染色体结构的两类核心调控因子——凝缩蛋白I（condensin I）与凝缩蛋白II（condensin II）进行快速降解实验后发现，这两种复合物在前体淋巴细胞的细胞分裂过程中均为必需，但在其分化形成的外周淋巴细胞子代细胞中则非必需。这种可推广的实验方法为小鼠模型中内源蛋白质剂量的调控提供了前所未有的时间精度，其在研究核心生物学通路以及在哺乳动物组织中开展药物活性建模方面均具有重要应用价值。