Structural/Function B Cell Differentiation Antigens

描述（由申请人提供）：在这项资助中，主要目标是研究调节处于细胞周期氧化石墨烯阶段的静止B细胞（氧化石墨烯B细胞）或离开氧化石墨烯进入细胞周期的机制。我们发现半胱天冬酶——一个与B细胞程序性死亡有关的半胱氨酸蛋白酶家族——也调节B细胞进入细胞周期。caspase-6抑制剂VEID可阻断氧化石墨烯B细胞的增殖。然而，caspase抑制剂不会阻断凋亡抑制剂（lAPs）的诱导。我们的数据表明，所有诱导B细胞进入细胞周期的模式都需要半胱天冬酶的共同途径。我们的目标是：目的1：明确B细胞中caspase激活的要求，即B细胞中caspase激活的上游信号通路。我们将测试不同的受体是否激活氧化石墨烯B细胞中相同或不同的半胱天冬酶。我们将验证T细胞依赖性（TD）与T细胞非依赖性（TI）信号受体在氧化石墨烯B细胞中激活相似或不同的半胱天冬酶途径的假设。我们将定义激活B细胞中caspase-6和-8所需的上游途径。使用显性阴性（DN）形式的FADD或caspase-6和来自caspase-6敲除小鼠的B细胞，我们将测试caspase-6的激活是否需要caspase-8的激活，反之亦然。我们还将测试当clAPs通过CD40激活时，是否有助于选择性激活caspase -6和-8以及细胞周期进入。目标2。我们将验证caspase-6在氧化石墨烯B细胞进入细胞周期并激活生存程序时切割一组功能底物的假设。首先，我们将描述在抑制caspase-6时观察到的细胞周期阻滞。其次，我们将定义caspase-6的底物并评估它们在B细胞中的作用。我们将定义caspase-6被激活后在B细胞中的去向，以及caspase-6底物SATB1如何在B细胞中受到caspase-6的调节。目标3。我们将描述caspase-6 -/-小鼠的B细胞缺陷，并比较野生型与CD40 -/-或caspase-6 -/-小鼠中B细胞亚群的存活率。我们预测caspase-6和CD40是最佳B细胞存活所必需的。我们还将测试半胱天冬酶是否选择性地调节B细胞亚群的稳态和扩增。这些研究将为正常B细胞、恶性B细胞和自身免疫性疾病的B细胞存活调控机制提供新的见解

DESCRIPTION (provided by applicant): In this grant the major goal is to investigate mechanisms regulating quiescent B cells either poised in the GO stage of the cell cycle (GO B cells) or leaving GO to enter the cell cycle. We have found that caspases- a family of cysteine proteases involved in programmed death of B cells- also regulates B cell entry into the cell cycle. The caspase-6 inhibitor VEID blocks proliferation of GO B cells. However, caspase inhibitors do not block induction of inhibitors of apoptosis (lAPs). Our data suggest caspases are required for a pathway common to all modes of inducing B cells into the cell cycle. Our Aims are: Aim 1: To define the requirements for caspase activation in B cells, i.e., the signaling pathways upstream of caspase activation in B cells. We will test whether or not different receptors activate the same or distinct sets of caspases in GO B cells. We will test the hypothesis that T cell dependent (TD) vs. T cell independent (TI) signaling receptors activate similar or distinct caspase pathways in GO B cells. We will define the upstream pathways required for activating caspase-6 and -8 in B cells. Using a dominant negative (DN) form of FADD or caspase-6 and B cells from caspase-6 knockout mice, we will test if activation of caspase-6 is required for activation of caspase-8 or vice versa. We will also test if clAPs, when activated via CD40, contribute to the selective activation of caspases -6 and -8 and ceil cycle entry. Aim 2. We will test the hypothesis that caspase-6 cleaves a functional set of substrates in GO B cells as they enter the cell cycle and activate a survival program. First, we will characterize the cell cycle block observed upon inhibition of caspase-6. Second, we will define substrates for caspase-6 and assess their roles in B cells. We will define where caspase-6 goes in B cells after they are activated and how the caspase-6 substrate, SATB1, is regulated by caspase-6 in B cells. Aim 3. We will characterize the B cell defects in caspase-6 -/- mice and compare the survival of B cell subsets in wildtype vs. CD40 -/- or caspase-6 -/- mice. We predict that caspase-6 and CD40 are required for optimal B cell survival. We will also test if caspases selectively regulate homeostasis and expansion of B cell subsets. These studies will provide new insights into the mechanisms, which regulate the survival of normal B cells, malignant B cells and B cells contributing to autoimmune diseases