Degron models: a toolbox for rapid in vivo depletion of essential proteins regulating mRNA metabolism.

Due to their essentiality, studying proteins involved in fundamental processes in vivo is challenging. PROTAC-based systems offer time-controlled protein depletion, but their characterization in vivo remains limited. Here, with an efficient direct zygote editing protocol, we generate degron-tag models (dTAG/FKBP or BromoTag) for seven genes involved in therapeutic and endogenous mRNA metabolism (Cnot1, Pan2, Tent5a, Tent4b, Dcp2, Rnasel, Tsg101). Degron tags occasionally cause phenotypes that can be mitigated by tag position or tagging system change. In cells, both approaches yield rapid and sustained degradation. In mice, dTAG depletion is effective but varies by protein and administration route, whereas BromoTag shows no in vivo activity. We showcase the utility of these models through an analysis of CNOT1's roles in cell division, immunity, and poly(A) tail maintenance. We present a valuable toolbox for studying mRNA metabolism in mammalian models, while providing a benchmark for applying degron-tag models to study other biological processes.