MafB and c-Maf is the member of large Maf family transcription factors well known to be specifically expressed in monocyte-macrophage lineage of hematopoietic cells. Recently we and other groups ...reported the minor consequences of either MafB or c-Maf single deficiency in the fetal liver macrophages. To address the further function of MafB and c-Maf in macrophage, we performed microarray and RT-PCR analysis of Mafb-/- macrophage and Mafb, c-Maf compound double KO (MafB-/-::c-Maf-/-) fetal liver. Interestingly, we found that reduction of C1qa, a member of the first component of the classical complement pathway, was observed in both Mafb-/- and MafB-/-::c-Maf-/- macrophages compared with wild type. C1qa deficiency is known to result in defect of clearance of apoptotic cells in macrophages. Consistent with this evidence, Mafb-/-, and MafB/c-Maf compound double hetero (MafB+/-::c-Maf+/-) macrophage failed to uptake of apoptosis induced Jurkat cells. Moreover, ectopic expression of MafB and c-Maf increased C1qa promoter-driven luciferase activity through the Maf recognition element in C1qa promoter. These results suggest that MafB and c-Maf was important for the clearance of apoptotic cells via regulation of C1qa.
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