ABSTRACT
Phospholipase
Cγ2 (PLCγ2) is a critical signaling effector of the
B-cell receptor (BCR). Here we show that PLCγ2 deficiency
impedes early B-cell development, resulting in an increase of
B220+ CD43+
BP-1+ CD24hi pre-BCR+
large pre-B cells. PLCγ2 deficiency impairs pre-BCR-mediated
functions, leading to enhanced interleukin-7 (IL-7) signaling and
elevated levels of RAGs in the selected large pre-B cells.
Consequently, PLCγ2 deficiency renders large pre-B cells
susceptible to transformation, resulting in dramatic acceleration of
Myc-induced lymphomagenesis.
PLCγ2
−/−
Eμ-Myc transgenic mice mainly develop lymphomas of
B220+ CD43+
BP-1+ CD24hi pre-BCR+
large pre-B-cell origin, which are uncommon in wild-type
Eμ-Myc transgenics. Furthermore, lymphomas from
PLCγ2
−/−
Eμ-Myc transgenic mice exhibited a loss of
p27Kip1 and often displayed alterations in Arf or p53. Thus,
PLCγ2 plays an important role in pre-BCR-mediated early B-cell
development, and its deficiency leads to markedly increased pools of
the most at-risk large pre-B cells, which display hyperresponsiveness
to IL-7 and express high levels of RAGs, making them prone to secondary
mutations and Myc-induced
malignancy.