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。本研究旨在了解两个重要的信号分子PLC31和PLC32在B淋巴细胞发育（包括清除自身反应性B细胞）中的作用，以及PLC3s调节这些过程的分子机制。该研究可能为自身免疫和免疫缺陷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新靶点。

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. PUBLIC HEALTH RELEVANCE This proposal seeks to understand the roles of two important signaling molecules PLC31 and PLC32 in the development of B lymphocytes, including the removal of autoreactive B cells, and the molecular mechanism by which PLC3s regulate these processes. The study may provide new clues to the molecular pathogenesis of autoimmune and immunodeficiency diseases, and help identify novel targets for specific therapies.