CNOT3 supports ILC2 differentiation and function by destabilizing Tbx21 and Rorc transcripts

Innate lymphoid cells (ILCs) include T-bet-dependent NK and ILC1 cells, GATA-3-dependent ILC2 cells, and RORγt-dependent ILC3 cells. Their functional and developmental regulation at the posttranscriptional level remains elusive. The CCR4-NOT complex plays a central role in mRNA decay by mediating deadenylation. To explore the overall impact of mRNA decay on ILCs, we conditionally deleted Cnot3, an essential subunit of the CCR4-NOT complex. Loss of CNOT3 in ILC2 cells led to aberrant expression of T-bet and RORγt, accompanied by upregulation of type 1 and type 3 signature genes. Mechanistically, CNOT3 targeted the 3' untranslated regions of Tbx21 and Rorc mRNAs through interactions with Roquin and ZFP36L1, respectively. Elevated T-bet expression in CNOT3-deficient ILC2 cells suppressed GATA-3 levels, thereby impairing type 2 immune responses in models of airway allergy and helminth infection. Thus, our findings reveal that CNOT3 maintains ILC2 differentiation and function by restricting type 1 and type 3 transcriptional programs.