B-cell Intrinsic Regulation of Antibody Mediated Immunity by Histone H2A Deubiquitinase BAP1 [RNA-seq]

BAP1 is a deubiquitinase (DUB) of the Ubiquitin C-terminal Hydrolase (UCH) family that regulates gene expression and other cellular processes, through its direct catalytic activity on the repressive epigenetic mark histone H2AK119ub, as well as several other substrates. BAP1 is also a highly important tumor suppressor, expressed and functional across many cell types and tissues. In recent work, we demonstrated a cell intrinsic role of BAP1 in the B cell lineage development in murine bone marrow, however the role of BAP1 in the regulation of B cell mediated humoral immune response has not been previously explored. In the current study, we demonstrate that a B-cell intrinsic loss of BAP1 function in activated B cells in the Bap1fl/fl Cγ1-cre murine model results in a severe defect in antibody production, with altered dynamics of germinal centre B cell, memory B cell, and plasma cell numbers. At the cellular and molecular level, BAP1 was dispensable for B cell immunoglobulin class switching but resulted in an impaired proliferation of activated B cells, with genome-wide dysregulation in histone H2AK119ub levels and gene expression. In summary, our study establishes the B-cell intrinsic role of BAP1 in antibody mediated immune response and indicates its central role in the regulation of the genome-wide landscapes of histone H2AK119ub and downstream transcriptional programs of B cell activation and humoral immunity. To further analyze the role of BAP1 in the transcriptional and epigenetic regulation of B cell activation, RNA-Seq gene expression analysis was conducted on germinal centre B cells isolated from the spleen of Bap1fl/fl Cγ1-cre and control Bap1+/+ Cγ1-cre mice at day 11-14 post-SRBC immunization, with the cells gated for FACS-sort.