Identification of novel STAT6-regulated proteins in mouse B cells by comparative transcriptome and proteome analysis

IL-4/STAT6-regulated transcriptome and proteome were compared in primary B cells isolated from wild-type and STAT6-deficient mice. B cells were purified from the spleen and stimulated in vitro with anti-CD40 and LPS or anti-IgM-F(ab)2 in the presence or absence of IL-4. Transcriptome analysis was performed with oligonucleotide microarrays. Global relative quantification of proteins was achieved by gel-enhanced label-free liquid chromatography/mass spectrometry (LC/MS). Hierarchical clustering and principal component analysis revealed that IL-4-induced changes of the transcriptome were almost completely dependent on STAT6. In contrast, the quantitative proteome analysis revealed that the expression of many IL-4-regulated proteins changes even in the absence of STAT6. The top 75 proteins with changes in abundance levels induced by IL-4 in a STAT6-dependent manner were also found to be regulated at the transcriptional level. Most of these proteins were not previously known to be regulated by STAT6 in B cells. We confirmed the MS-based quantitative proteome data by flow cytometric and Western blot analysis of selected proteins. This study provides a framework for further functional characterization of STAT6-regulated proteins in B cells that might be involved in germinal center formation and class switch recombination.