Cutting edge: STAT6 serves as a positive and negative regulator of gene expression in IL-4-stimulated B lymphocytes.

STAT6 plays an important role in IL-4-mediated B cell activation and differentiation. To identify primary and secondary target genes of STAT6, gene expression profiles of IL-4-stimulated B cells from STAT6+/+ vs STAT6-/- mice were compared. Statistical analysis revealed that 106 distinct probe sets including 70 known genes were differentially expressed between the 2 genotypes. These genes include transcription factors, kinases, and other enzymes, cell surface receptors, and Ig H chains. Surprisingly, although 31 genes were expressed at higher levels in STAT6+/+ B cells, 39 genes were expressed at higher abundance in STAT6-/- B cells. This result implies both positive and negative regulatory functions of STAT6 in IL-4-mediated gene expression. Furthermore, IL-4 induces expression of the transcription factor Krox20, which is required for maximal IL-4-induced transcription.