Project description:High expression of the FOXP1 transcription factor distinguishes the highly aggressive Activated B Cell (ABC) type of Diffuse Large B Cell Lymphoma (DLBCL) from the more indolent Germinal Center (GCB) DLBCL subtype and is correlated with poor prognosis. A genetic or functional role for FOXP1 in lymphomagenesis and/or tumor maintenance, however, remains unknown. Here, we report that sustained expression of FOXP1 is necessary for ABC DLBCL cell line survival. Genome-wide transcript profiling reveals that FOXP1 acts directly and indirectly by enforcing expression of known ABC DLBCL hallmarks, including the classical NF-kappaB survival pathway. Our data further suggest that FOXP1 maintains the ABC subtype distinction by repressing gene expression programs dominant in GCB DLBCL and supports a model in which the target of ABC DLBCL transformation is a transitory cell type en route from the germinal center B cell to the terminally differentiated plasma cell.
Project description:To elucidate the direct targets of ZEB2 in ABCs, we performed high-throughput sequencing of regulome by ATAC-seq, CUT & Tag, and CUT & RUN, leading to the identification the accessible sites with ZEB2 binding. Among the genes differentially expressed by Zeb2 deficiency, we found 33 candidate target genes of ZEB2, with 22 repressed and 11 activated by ZEB2. The critical transcription factor Mef2b, essential for GC development, was repressed by ZEB2. This direct regulation was mapped to a conserved region about 20kb downstream of Mef2b's exon I TSS, enriched with enhancer-associated features in both human and mouse.