Identifying new genes involved in thymic involution

项目总结/摘要 胸腺是负责产生T细胞的主要免疫器官，其功能随着T细胞的减少而下降。 年龄（退化）被认为是与年龄相关的免疫衰老的重要因素。有强有力 有证据表明，衰老相关的胸腺退化是在青年时期由胸腺中的机制启动的。 上皮细胞（TEC）的细胞毒性，导致它们的消耗和房室组织的丧失。尽管它的核心作用 在T细胞获得性免疫的形成和维持中的作用以及胸腺的多效性负面影响 衰老过程中的退化，令人惊讶的是，胸腺器官功能，体内平衡和 已经确定了内卷。一个关键的转录因子，FOXN1，已知是一个主要的调节器， 胸腺发育和产后维护。然而，其调节机制和途径 它通过什么影响TEC的发展，功能和老化相关的退化仍然是未知的。个tec 胸腺细胞是整个胸腺细胞的一个小的子集，并且众所周知难以通过实验分离。因此，识别 通过基于基因表达的或生物化学分析来确定调节子和效应子是困难的，并且在任何情况下都是可行的。 专门针对TEC子集或特定年龄。考虑到胸腺退化的渐进性， 这些实验旨在确定胸腺功能的关键调节因子，并随着年龄的增长而维持， 挑战性正向遗传筛选是根据基因功能鉴定基因的有力工具， 允许无偏见地发现新的途径和机制，但对于衰老相关的 表型在最近的一个R21资助的项目中，我的实验室使用ENU进行了一个显性修饰符筛选 诱变以鉴定新的突变，当杂合时，其增强（增加严重性）或 抑制（挽救/降低严重性）Foxn1Z/Z胸腺退化表型。我们发现了18个 修饰子系，包括增强子和抑制子。因为它们影响Foxn1表达和/或 在胸腺过早退化的Foxn1Z/Z模型中起作用，我们的假设是这些修饰物代表了 以前未识别的基因，通常作用于促进或抑制衰老相关的胸腺退化。在 目前的建议，我们将跟进我们成功的初步项目，以确定我们的试点中发现的改性剂 筛选，并测试它们是否影响正常老化过程中的退化轨迹。这种新颖的方法， 研究胸腺退化的分子基础代表了一种潜在的变革性方法， 识别控制胸腺功能和衰老相关退化的新基因、途径和机制。

Project Summary/Abstract The thymus is the primary immune organ responsible for the generation of T cells, and its functional decline with age (involution) is considered a significant contributor to aging-associated immunosenescence. There is strong evidence that aging-related thymic involution is initiated during youth by mechanisms that operate in thymic epithelial cells (TECs) to result in their depletion and loss of compartmental organization. Despite its central role in the formation and maintenance of T cell adaptive immunity and the pleiotropic negative impacts of thymus involution during aging, surprisingly few molecular regulators of thymus organ function, homeostasis, and involution have been identified. A key transcription factor, FOXN1, is known to be a primary regulator of both thymus development and postnatal maintenance. However, the mechanisms of its regulation and the pathways through which it affects TEC development, function, and aging-related involution remain largely unknown. TECs are a small subset of total thymus cells and are notoriously difficult to isolate experimentally. Thus, identifying regulators and effectors by gene expression-based or biochemical analysis is difficult, and in any case would be specifically targeted to a TEC subset or specific age. Given the gradual nature of thymic involution, designing such experiments to identify key regulators of thymus function and maintenance with aging would be doubly challenging. Forward genetic screens are powerful tools for identifying genes based on their function, thus allowing unbiased discovery of novel pathways and mechanisms, but are not generally practical for aging-related phenotypes. In a recent R21-funded project, my lab performed a dominant modifier screen using ENU mutagenesis to identify novel mutations that, when heterozygous, either enhance (increase the severity) or suppress (rescue/reduce the severity) the Foxn1Z/Z thymic involution phenotype. We identified 18 dominant modifier lines, including both enhancers and suppressors. Because they impact Foxn1 expression and/or function in the Foxn1Z/Z model of premature thymic involution, our hypothesis is that these modifiers represent previously unrecognized genes that normally act to promote or restrain aging-related thymic involution. In the current proposal, we will follow up on our successful initial project to identify the modifiers found in our pilot screen, and test whether they affect the trajectory of involution during normal aging. This novel approach to investigating the molecular basis of thymus involution represents a potentially transformative approach to identifying new genes, pathways, and mechanisms that control thymus function and aging-related involution.