MAFB drives differentiation by permitting WT1 binding to podocyte 1 specific promoters

Podocytes are highly specialized cells, but their chromatin status and the precise molecular events leading to their differentiation remain poorly defined. Here we used ChIP-Seq analysis for H3K4me3, H3K4me1 and H3K27me3 to establish the histone methylation map in adult mouse podocytes. Our data demonstrate open chromatin across podocyte specific genes and reveals that genes expressed in the mesoderm lineage become actively repressed upon podocyte differentiation. To better understand the transcriptional control of podocyte differentiation, we studied the role of transcription factor MAFB. ChIP-Seq experiments and functional analysis in conditional knockout mice identified a set of direct MAFB targets including Nphs1, Nphs2, Vegfa and Tcf21. Loss of MafB led to the deposition of extracellular matrix, progressive foot process effacement, and kidney disease. ChIP experiments in knockout animals revealed that during development MAFB is essential for H3K4me3 methylation and the recruitment of WT1 to the promoters of the podocyte specific genes Nphs1 and Nphs2. Taken together our data reveal the crucial function of MAFB by permitting chromatin accessibility at podocyte-specific genes during development and maintaining terminal differentiation in adults.