Functional analysis of novel genes involved in the regulation of B cell activation and death

为了探索驱动静止B细胞进入细胞周期的分子事件，我们采用了一种改进的减法克隆策略来鉴定新的基因，这些基因的表达通过CD40被B细胞激活调控，CD40与激活T细胞瞬时表达的CD40配体相互作用。在过去的两年里，我们重点研究了Clast1和Clast5基因在体内的功能。来自Clast1转基因小鼠的B细胞对抗原受体信号传导具有高反应性。此外，对t依赖性抗原的初级和次级免疫反应都增强了。这些初步发现有力地提示了Clast1在增强B细胞应答中的作用。在Clast5转基因小鼠中，脾脏和胸腺的大小和细胞数量都大大减少。此外，B细胞对各种刺激的反应受损。骨髓中的祖B细胞对IL-7的生长反应显著降低。这些结果表明，Clast5是B细胞活化的负调节因子，可能决定B细胞反应的阈值。我们正在培育Clast1和Clast5敲除小鼠。

To explore the molecular events that drive a resting B cell to enter the cell cycle, we have employed a modified subtractive cloning strategy to identify novel genes whose expression is regulated upon B cell activation through CD40, which interacts with CD40 ligand transiently expressed by activated T cells. In the past two years, we focused on the function in vivo of Clast1 and Clast5 genes. B cells from Clast1 tratnsgenic mice are hyper-reactive to antigen receptor signaling. In addition, both primary and secondary immune responses to T-dependent antigens are enhanced. These preliminary findings strongly suggest a role for Clast1 in augmenting B cell responses. In Clast5 transgenic mice, the size and cell number of both spleen and thymus are greatly reduced. Moreover, B cell responses to a variety of stimuli are impaired. Progenitor B cells in the bone marrow have a significantly reduced growth response to IL-7. These results indicate that Clast5 is a negative regulator of B cell activation and may serve to determine the threshold of B cell responses. We are in the process of generating Clast1 and Clast5 knock out mice.