Asynchronous combinatorial action of four regulatory factors activates Bcl11b for T cell commitment. Mus musculus

During T cell development, multipotent progenitors relinquish competence for other fates and commit to the T cell lineage by turning on Bcl11b, which encodes a transcription factor. To clarify lineage commitment mechanisms, we followed developing T cells at the single-cell level using Bcl11b knock-in fluorescent reporter mice. Notch signaling and Notch activated transcription factors collaborate to activate Bcl11b expression irrespectively of Notch-dependent proliferation. These inputs work via three distinct, asynchronous mechanisms: an early locus ‘poising’ function dependent on TCF-1 and GATA-3, a stochastic-permissivity function dependent on Notch signaling, and a separate amplitude-control function dependent on Runx1, a factor already present in multipotent progenitors. Despite their necessity for Bcl11b activation, these inputs act in a stage specific manner, providing a multitiered mechanism for developmental gene regulation. Overall design: Two sets of samples were generated from DN T-cell sub-populations derived from culture of bone marrow progenitors from mice containing a knock-in Bcl11b-YFP reporter