The LIN28:pre-let-7:TUTase ternary complex regulates pluripotency and oncogenesis by controlling processing of the let-7 family of microRNAs. The complex oligouridylates the 3' ends of pre-let-7 molecules, leading to their degradation via the DIS3L2 exonuclease. Previous studies suggest that components of this complex are potential therapeutic targets in malignancies that aberrantly express LIN28. In this study we developed a functional epitope selection approach to identify nanobody inhibitors of the LIN28:pre-let-7:TUT4 complex. We demonstrate that one of the identified nanobodies, Nb-S2A4, targets the 106-residue LIN28:let-7 interaction (LLI) fragment of TUT4. Nb-S2A4 can effectively inhibit oligouridylation and monouridylation of pre-let-7g in vitro. Expressing Nb-S2A4 allows maturation of the let-7 species in cells expressing LIN28, highlighting the therapeutic potential of targeting the LLI fragment.

中文翻译：

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靶向TUT4的LIN28：let-7相互作用片段的纳米抗体可阻止let-7的尿嘧啶化。

LIN28：pre-let-7：TUTase三元复合物通过控制let-7家族microRNA的加工来调节多能性和致癌作用。该复合物寡聚谷氨酰化pre-let-7分子的3'端，导致其通过DIS3L2核酸外切酶降解。先前的研究表明，这种复合物的成分是异常表达LIN28的恶性肿瘤的潜在治疗靶标。在这项研究中，我们开发了一种功能性的抗原决定簇选择方法来鉴定LIN28：pre-let-7：TUT4复合物的纳米抗体。我们证明已鉴定的纳米抗体之一Nb-S2A4靶向TUT4的106个残基的LIN28：let-7相互作用（LLI）片段。Nb-S2A4可以在体外有效抑制pre-let-7g的寡尿和单尿。表达Nb-S2A4可以使表达LIN28的细胞中的let-7物种成熟，