Description
The inhibitor of DNA binding 2 (Id2) is essential for NK cell development with its canonical role in this pathway being to antagonize E-proteins, silencing E-box gene expression and subsequent commitment to the T and B cell lineages. However, how E-box genes prevent NK cell development and homeostasis remains enigmatic. Here we identify a key role for Id2 in regulating the threshold for IL-15 receptor signaling and homeostasis of NK cells by repressing multiple E-protein target genes including Socs3. Deletion of Id2 in mature NK cells was incompatible with their homeostasis due to impaired IL-15 receptor signaling. Id2-null NK cells displayed impaired IL-15 mediated JAK1/STAT5 phosphorylation, compromised metabolic function and enhanced apoptosis. Remarkably, Id2-null NK cell homeostasis could be fully rescued in vivo by IL-15 receptor stimulation and partially rescued by genetic ablation of Socs3. During normal NK cell maturation we observed an inverse correlation between the expression levels of E-protein target genes and Id2. These results shift the current paradigm on the role of Id2, indicating that it is not only required to antagonize E-proteins during NK cell commitment, but constantly required to titrate E-protein activity to regulate NK cell fitness and responsiveness to IL-15. Overall design: Transcriptional profiling of wild type and Id2-null natural killer (NK) cells using RNA sequencing