Identification of novel transcriptional regulators involved in differentiation and function of monocyte and macropahge

Maturation of blood monocytes into tissue macrophages and subsequent inflammatory response was mimicked in U937 cells of human histocytic lymphoma origin. Whole genome array analysis was employed to evaluate gene expression profile to identify underlying transcriptional networks implicated during the processes of differentiation and inflammation. In addition to already known transcription factors (i.e. MAFB, EGR, IRF, BCL6, NFkB, AP1, Nur77), gene expression analysis further revealed novel genes (i.e. MEF2, BRI, HLX, HDAC5, H2AV, TCF7L2, NFIL3) previously uncharacterized to be involved in the differentiation process. A total of 58 selected genes representing cytokines, chemokines, surface antigens, signaling molecules and transcription factors were validated by real time PCR and compared to primary monocyte-derived macrophages. Beside the verification of several new genes, the comparison reveals individual heterogeneity of blood donors. U937 cells were differentiated into monocytes by VitD3 (24 hrs) or into marophages by PMA (6 hrs, 12 hrs, 24 hrs and 32 hrs). Cells differentiated for 24 hrs by PMA are further stimulated by LPS for 2 hrs. Total RNA from 6 case samples were subjected to differential gene expression in comparison to undifferentiated U937 cells.