Regulation of interleukin 7-dependent immunoglobulin heavy-chain variable gene rearrangements by transcription factor STAT5

Rearrangement of immunoglobulin heavy-chain variable (V_H) gene segments has been suggested to be regulated by interleukin 7 signaling in pro-B cells. However, the genetic evidence for this recombination pathway has been challenged. Furthermore, no molecular components that directly control V_H gene rearrangement have been elucidated. Using mice deficient in the interleukin 7-activated transcription factor STAT5, we demonstrate here that STAT5 regulated germline transcription, histone acetylation and DNA recombination of distal V_H gene segments. STAT5 associated with V_H gene segments in vivo and was recruited as a coactivator with the transcription factor Oct-1. STAT5 did not affect the nuclear repositioning or compaction of the immunoglobulin heavy-chain locus. Therefore, STAT5 functions at a distinct step in regulating distal V_H recombination in relation to the transcription factor Pax5 and histone methyltransferase Ezh2.