Rapid and efficient adaptation of the dTAG system in mammalian development reveals stage specific requirements of NELF

SUMMARY Targeted protein degradation methods offer a unique avenue to assess a protein’s function in a variety of model systems. Recently, these approaches have been applied to mammalian cell culture models, enabling unprecedented temporal control of protein function. However, the efficacy of these systems at the tissue and organismal levels in vivo is not well established. Here, we tested the functionality of the degradation tag (dTAG) degron system in mammalian development. We generated a homozygous knock-in mouse with a FKBP F36V tag fused to Negative elongation factor b (Nelfb) locus, a ubiquitously expressed protein regulator of transcription. In the first validation of targeted endogenous protein degradation across mammalian development, we demonstrate that irrespective of the route of administration the dTAG system is safe, rapid, and efficient in embryos from the zygote to midgestation stages. Additionally, acute early depletion of NELFB revealed a specific role in zygote-to-2-cell development and Zygotic Genome Activation (ZGA). HIGHLIGHTS genetically engineered mouse model harboring a FKBP F36V knock-in to evaluate kinetics and efficacy of the dTAG degron system in vivo system is non-toxic, and allows acute and efficient degradation of a FKBP F36V - tagged endogenous protein during in utero embryo development system nables fine temporal degradation and reversibility of depletion across embryonic stages stage-specific depletion reveals a role for NELFB during mouse ZGA