Phospholipase Cγ2 Contributes to Light-Chain Gene Activation and Receptor Editing

Abstract

ABSTRACT Phospholipase Cγ2 (PLCγ2) is critical for pre-B-cell receptor (pre-BCR) and BCR signaling. Current studies discovered that PLCγ2-deficient mice had reduced immunoglobulin λ (Igλ) light-chain usage throughout B-cell maturation stages, including transitional type 1 (T1), transitional type 2 (T2), and mature follicular B cells. The reduction of Igλ rearrangement by PLCγ2 deficiency was not due to specifically increased apoptosis or decreased proliferation of mutant Igλ + B cells, as lack of PLCγ2 exerted a similar effect on apoptosis and proliferation of both Igλ + and Igκ + B cells. Moreover, PLCγ2-deficient Ig HEL transgenic B cells exhibited an impairment of antigen-induced receptor editing among both the endogenous λ and κ loci in vitro and in vivo. Importantly, PLCγ2 deficiency impaired BCR-induced expression of IRF-4 and IRF-8, the two transcription factors critical for λ and κ light-chain rearrangements. Taken together, these data demonstrate that the PLCγ2 signaling pathway plays a role in activation of light-chain loci and contributes to receptor editing.