PLC?s in B cell biology and autoimmunity

描述（申请人提供）：早期B细胞发育和晚期B细胞成熟分别由前B细胞受体（BCR）和BCR发出的信号调节。在成熟过程中，B细胞对自身抗原的耐受性是通过克隆性缺失、受体编辑和激活来建立的，这些过程由BCR发出的信号控制。扭曲的前BCR/BCR信号通常导致B细胞发育缺陷、B细胞耐受性破坏和免疫缺陷和自身免疫性疾病的发生。来自pre-BCR/BCR调控B细胞发育和耐受性的信号尚不完全清楚。磷脂酶C3 （PLC3）是一种重要的脂质酶，参与BCR前/BCR信号传导。PLC3有两个同工异构体，PLC31和PLC32。plc32缺陷小鼠存活，早期和晚期B发育受损。我们最近的数据发现，PLC32在轻链位点的激活、自反应受体的编辑和B细胞能量的诱导中起着重要作用。PLC31缺乏导致妊娠中期早期胚胎死亡，因此无法分析其在B细胞发育中的作用。然而，我们对PLC31缺失的杂合小鼠（PLC31PLC32-/-）的研究表明，PLC31在B的发育中也起着重要作用。我们最近培育了PLC31基因可以条件失活的小鼠。利用转基因PLC31和PLC32基因的小鼠，我们有条件进一步研究PLC31/PLC32在B淋巴生成中的单独和联合作用，包括耐受性的建立，以及这两种PLC3s调节这一过程的机制。我们假设PLC31和PLC32在BCR前/BCR介导的功能和建立B细胞耐受性中发挥重要作用。为了验证我们的假设，我们提出了三个具体目标。1)确定PLC31的作用,结合角色PLC31和PLC32 pre - BCR-mediated B细胞发育早期,等位基因排斥本链,激活IgL链的基因座,和B细胞的形成,2)确定个人和结合PLC31的角色和PLC32 BCR -介导的B细胞成熟,受体编辑和诱导B细胞的无力,和3)研究PLC31的上游和下游通路和PLC32 pre-BCR / BCR信号。该研究旨在了解两种PLC3亚型在B淋巴生成中的作用，特别是耐受的建立，以及它们传递来自前BCR/BCR的信号的机制。该研究可能为自身免疫性疾病的分子发病机制提供新的线索，并有助于确定特异性治疗的靶点。

DESCRIPTION (provided by applicant): Early B cell development and late B cell maturation are regulated by signals emanating from the pre-B cell receptor (BCR) and BCR, respectively. During maturation, B cell tolerance to self-antigens is established through clonal deletion, receptor editing and anergy, which are controlled by signals emanating from the BCR. Distorted pre-BCR/BCR signaling often results in defective B cell development, breakdown of B cell tolerance and development of immunodeficiency and autoimmune diseases. Signals from the pre-BCR/BCR that regulate B cell development and tolerance are not fully understood. Phospholipase C3 (PLC3) is an important lipid enzyme involved in pre-BCR/BCR signaling. PLC3 has two isoforms, PLC31 and PLC32. PLC32-deficient mice are viable and have impaired early and late B development. Our recent data find that PLC32 plays an important role in activation of light chain loci, editing of self-reactive receptors and induction of B cell anergy. PLC31 deficiency results in early embryonic death at midgestation, precluding analysis of its role in B cell development. However, our studies of PLC32-deficient mice that are heterozygous for PLC31-deficiency (PLC31PLC32-/-) indicate that PLC31 also plays an important role in B development. We have recently generated mice in which the PLC31 gene can be conditionally inactivated. With the mice that have genetically modified PLC31 and PLC32 genes, we are well-positioned to further study the individual and combined roles of PLC31/PLC32 in B lymphopoiesis, including tolerance establishment, and the mechanism by which both PLC3s regulate the process. We hypothesize that both PLC31 and PLC32 play an important role in pre- BCR/BCR-mediated functions and in establishing B cell tolerance. To test our hypothesis, we propose three specific aims. We will 1) determine the role of PLC31 and combined roles of PLC31 and PLC32 in pre- BCR-mediated early B cell development, allelic exclusion of IgH chain, activation of the IgL chain loci, and formation of the B cell repertoire, 2) determine the individual and combined roles of PLC31 and PLC32 in BCR- mediated B cell maturation, receptor editing and induction of anergy in B cells, and 3) study the upstream and downstream pathways of PLC31 and PLC32 during pre-BCR/BCR signaling. The proposed research seeks to understand the roles for the two PLC3 isoforms in B lymphopoiesis, especially tolerance establishment, and the mechanism by which they relay the signals from the pre-BCR/BCR. The study may provide new clues to the molecular pathogenesis of autoimmune diseases and help identify targets for specific therapies.