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.