Control of Lineage Commitment in Developing Thymocytes

描述（由申请人提供）：本项目的总体目标是了解控制α/β胸腺细胞向CD 4或CD 8谱系的替代定型的机制，并确保辅助受体表达与TCR限制为I类或II类MHC之间的精确相关性。尽管现在广泛接受的是，响应于I类或II类配体的参与的替代TCR信号传导负责启动替代谱系定型，但通过其实现这一点的细胞内途径仍然未知。我们以前已经描述了一种独特的自发突变小鼠，称为“辅助缺陷”或HD，其中辅助受体表达和MHC特异性之间的相关性被打破，使得所有胸腺细胞，特别是II类限制性胸腺细胞，采用CD 8谱系。我们现在已经初步鉴定出缺陷基因为cKrox，这是POK亚家族蛋白质的一个基本上未被表征的成员，POK亚家族蛋白质被定义为包含Kr和Kr。
ppel样锌指和BTB/POZ结构域，后者涉及转录抑制。基于这一最近的发现，目前的建议集中在定义的功能特性，调节和细胞分布的cKrox在发育胸腺细胞。我们提出以下具体目标： 1)明确证明cKrox对应于HD基因座。 2)确定cKrox活性如何在I类与II类特异性胸腺细胞中差异调节。 3)从功能上剖析cKrox的锌指和BTB/POZ结构域在谱系定型中的作用。

DESCRIPTION (provided by applicant): The overall aim of this project is to understand the mechanisms that control alternative commitment of alpha/beta thymocytes to the CD4 or CD8 lineages and that ensure the precise correlation between coreceptor expression and TCR restriction to class I or II MHC. Although it is now widely accepted that alternate TCR signaling in response to engagement by class I or II ligands is responsible for initiating alternate lineage commitment, the intracellular pathways through which this is accomplished remain unknown. We have previously described a unique spontaneous mutant mouse, termed "helper deficient" or HD, in which the correlation between coreceptor expression and MHC specificity breaks down, such that all thymocytes, in particular class II-restricted ones, adopt the CD8 lineage. We have now tentatively identified the defective gene as cKrox, a largely uncharacterized member of the POK subfamily of proteins, which are defined as containing both a Kr
ppel-like zinc finger and a BTB/POZ domain, the latter implicated in transcriptional repression. Based on this very recent finding, the current proposal focuses on defining the functional characteristics, regulation and cellular distribution of cKrox in developing thymocytes. We propose the following specific aims: 1) To definitively demonstrate that cKrox corresponds to the HD locus. 2) To determine how cKrox activity is differentially regulated in class I- versus class II-specific thymocytes. 3) To functionally dissect the roles of the zinc finger and BTB/POZ domains of cKrox in lineage commitment.