Impact of 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 generated 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 caused phenotypes that were often mitigated by tag position or tagging system change. In cells, both approaches yielded rapid and sustained degradation. In mice, dTAG depletion was effective but varied by protein and administration route, whereas BromoTag showed 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.