Pax5/B cell lineage specific activator protein (BSAP) is a B lineage-specific regulator that controls the B lineage-specific gene expression program and immunoglobulin gene VH to DJH recombination. Despite extensive studies on its multiple functions, little is known about how the activity of Pax5 is regulated. Here, we show that co-expression of histone acetyltransferase E1A binding protein p300 dramatically enhances Pax5-mediated transcriptional activation. The p300-mediated enhancement is dependent on its intrinsic histone acetyltransferase activity. Moreover, p300 interacts with the C terminus of Pax5 and acetylates multiple lysine residues within the paired box DNA binding domain of Pax5. Mutations of lysine residues 67 and 87/89 to alanine within Pax5 abolish p300-mediated enhancement of Pax5-induced Luc-CD19 reporter expression in HEK293 cells and prevent Pax5 to activate endogenous Cd19 and Blnk expression in Pax5−/− murine pro B cells. These results uncover a novel level of regulation of Pax5 function by p300-mediated acetylation.
This work was supported, in whole or in part, by National Institutes of Health Grants AR048592, AI073174, AI074948, and AI076475 (to Z. Z.). This work was also supported by funding from the University of Alabama at Birmingham and the University of Nebraska Medical Center and the Eppley Cancer Institute (to Z. Z.). Purchase of the Q-TOF mass spectrometer in the Shared Facility came from funds provided by the National Center for Research Resources (NCRR) Shared Instrumentation Grants S10 RR13795 and the University of Alabama at Birmingham Health Services Foundation General Endowment Fund (Water/Micromass Q-TOF). The Mass Spectrometry and Proteomics Core Facility at the University of Nebraska Medical Center is supported by the Nebraska Research Initiative.
