Structure and Function of the FOXP Family of Transcription Factors

描述(申请人提供)：拟议研究的长期目标是阐明FOXP转录因子在重要的生理过程中调节特定基因表达的分子机制。FOXP蛋白的突变与人类自身免疫性疾病(FOXP3)和言语障碍(FOXP2)有关。FOXP家族的其他成员也与肿瘤抑制(FOXP1)和肺发育(FOXP4)有关。尽管这些转录因子具有重要的生理功能，但其分子机制还不是很清楚。FoxP包含一个发散的叉头域和一些不同的功能基序，包括在叉头域之前的锌指/亮氨酸拉链基序。也有证据表明FOXP3和NFAT1物理上相互作用并协同结合复合DNA位点。因此，无论是通过固有的DNA结合还是与不同伙伴的相互作用，FOXP蛋白都具有与经典Fox蛋白相比独特的DNA识别机制，这反过来又决定了FOXP转录因子家族的转录特异性。本文提出的研究将通过X射线结晶学和生化方法表征FOXP蛋白及其与DNA和NFAT的络合物的结构和功能。目标1将专注于FOXP蛋白的叉头域，以表征其详细的DNA识别机制。目的2将分析锌指/亮氨酸拉链基序和更大的片段或全长FOXP蛋白的结构，以了解FOXP的其他区域如何调节这一蛋白家族的功能。目的3研究NFAT/FOXP相互作用的结构基础及其在T细胞基因表达中的潜在作用。本申请中提出的详细的生化和结构研究将为分析FOXP蛋白与疾病相关的突变机制和进一步研究它们在不同细胞过程中的正常生理作用提供分子基础。健康相关性：由于FOXP蛋白的突变与自身免疫性疾病和语言障碍有关，揭示其独特的DNA识别机制将有助于识别这些转录因子的潜在目标基因，这反过来又可以为人类语言发育和免疫耐受的机制提供关键的见解。这些见解可能导致诊断和治疗由FOXP蛋白故障引起的人类疾病的新方法。

DESCRIPTION (provided by applicant): The long-term goal of the proposed research is to elucidate the molecular mechanisms by which FOXP transcription factors regulate specific gene expression in physiologically important processes. Mutations in FOXP proteins have been linked to human autoimmune disease (FOXP3) and speech disorder (FOXP2). Other members of the FOXP family have been implicated in tumor suppression (FOXP1) and lung development (FOXP4). Despite their significant physiological functions, the molecular mechanisms of this family of transcription factors are not well understood. FOXP contains a divergent forkhead domain and a number of distinct functional motifs, including a zinc finger/leucine zipper motif preceding the forkhead domain. There is also evidence that FOXP3 and NFAT1 physically interact and bind composite DNA sites cooperatively. Thus, either through intrinsic DNA binding or interaction with distinct partners, FOXP proteins possess unique DNA recognition mechanisms as compared classical FOX proteins, which in turn determine the transcriptional specificity of the FOXP family of transcription factors. The research proposed here will characterize the structure and function of FOXP proteins and their complexes with DNA and NFAT by X-ray crystallography and biochemical methods. Aim 1 will focus on the forkhead domains of FOXP proteins to characterize their detailed DNA recognition mechanisms. Aim 2 will analyze the structure of the zinc finger/leucine zipper motif and larger fragments or full-length FOXP proteins to see how other regions of FOXP modulate the function of this family of proteins. Aim 3 will study the structural basis of NFAT/FOXP interaction and its potential function in T cell gene expression. The detailed biochemical and structural studies proposed in this application will provide a molecular basis for analyzing the mechanisms of disease- associated mutations in FOXP proteins and further investigation of their normal physiological roles in diverse cellular processes. Health Relevance: Because mutations in FOXP proteins are linked to autoimmune disease and speech disorder, uncovering their unique DNA recognition mechanisms will help identify potential target genes of these transcription factors, which in turn can offer crucial insights into the mechanisms of human language development and immunological tolerance. These insights may lead to new approaches to diagnosing and treating human diseases incurred by malfunction of FOXP proteins.