Ddx3xregulates B-cell development and light chain recombination in mice

Abstract

AbstractDdx3xencodes a DEAD box RNA helicase implicated in antiviral immunity and tumorigenesis. We find that hematopoieticDdx3xdeficiency inVav1-Cremice (ΔDdx3x) results in altered leukocyte composition of secondary lymphoid tissues, including a marked reduction in mature B cells. This paucity of peripheral B cells is associated with deficits in B-cell development in the bone marrow, including reduced frequencies of small pre-B cells. Bone marrow chimera experiments reveal a B-cell intrinsic effect ofDdx3xdeletion. Mechanistically, ΔDdx3xsmall pre-B cells exhibit lower expression ofBrwd1, a histone reader that restricts recombination at the immunoglobulin kappa (Igk)locus. In fact, the B-cell deficits in ΔDdx3xmice resemble those ofBrwd1mutant mice, and both strains of mice exhibit defectiveIgkrearrangement in small pre-B cells. The contribution ofDdx3xtoBrwd1expression and light chain rearrangement constitutes the first evidence of a role for an RNA helicase in promoting B-cell development.