Abstract
B cell development past the pro-B cell stage in mice requires the Cul4-Roc1-DDB1 E3 ubiquitin ligase substrate recognition subunit VprBP. Enforced Bcl2 expression overcomes defects in distal VH-DJH and secondary Vk-Jk rearrangement associated with VprBP insufficiency in B cells and substantially rescues maturation of marginal zone and Igλ+ B cells, but not Igk+ B cells. In this background, expression of a site-directed Igk L chain transgene increases Igk+ B cell frequency, suggesting VprBP does not regulate L chain expression from a productively rearranged Igk allele. In site-directed anti-dsDNA H chain transgenic mice, loss of VprBP function in B cells impairs selection of Igk editor L chains typically arising through secondary Igk rearrangement, but not selection of Igl editor L chains. Both H and L chain site-directed transgenic mice show increased B cell anergy when VprBP is inactivated in B cells. Taken together, these data argue that VprBP is required for the efficient receptor editing and selection of Igk+ B cells, but is largely dispensable for Igλ+ B cell development and selection, and that VprBP is necessary to rescue autoreactive B cells from anergy induction.