MicroRNA-15/16 Antagonizes c-Myb to Control Natural Killer Cell Maturation. Mus musculus

NK cells develop in the bone marrow and complete their maturation in peripheral organs, but the molecular events controlling maturation are incompletely understood. Utilizing an NK cell-specific miR-15/16 deficient genetic model (15aKO), we identified a critical role for miR-15/16 family microRNAs in the normal maturation of NK cells in vivo, with a specific reduction in mature CD11b+CD27- NK cells in multiple tissues. The mechanism responsible was a block in differentiation, since accelerated NK cell death was not evident, and earlier intermediates of NK cell maturation were expanded. Further, we identified Myb as a direct target of miR-15/16 in NK cells, with Myb expression increased in immature 15aKO NK cells. Following adoptive transfer, immature 15aKO NK cells exhibited defective maturation, which was rescued by ectopic miR-15/16 expression or Myb knockdown. Moreover, Myb overexpression resulted in defective NK cell maturation. Thus, miR-15/16 regulation of Myb controls the normal NK cell maturation program. Overall design: 3 technical replicates each of CD27+ 15a/16-1FKO NK cells, and CD27+ Ctrl NK cells