Project 2 - The role of Foxn1 in controlling the transition from thymus expansion to homeostasis

项目 2 - Foxn1 在控制胸腺扩张到稳态转变中的作用

• 批准号: 10470931
• 负责人: Nancy R Manley
• 金额: $ 56.17万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10470931
• 关键词: Adolescent; Adult; Affect; Age-Months; Alleles; Bioinformatics; Biometry; Bordetella pertussis; Cell Compartmentation; Cell Differentiation process; Cell physiology; Cells; Characteristics; Communicable Diseases; Cyclin-Dependent Kinases; Data; E2F transcription factors; Epithelial Cell Proliferation; Family member; Fetal Development; Gene Expression; Genetic Transcription; Goals; Growth; Homeostasis; Human; Immune response; Influenza B Virus; Longevity; Maps; Memory; Mus; Neonatal; Organ; Organ Size; Organizational Change; Perinatal; Peripheral; Pertussis; Phenotype; Population; Process; Proliferating; Publishing; Regulation; Retinoblastoma; Retinoblastoma Protein; Role; Stromal Cells; Stromal Change; T-Lymphocyte; Testing; Thymic epithelial cell; Thymus Gland; Tissue imaging; Transgenic Organisms; Vaccination; cell type; critical period; fetal; immune function; loss of function; mouse model; multiplexed imaging; mutant; neonatal period; overexpression; pathogen; perinatal period; postnatal; progenitor; programs; response; retinoblastoma pathway; single-cell RNA sequencing; transcription factor

Abstract There is growing evidence that thymic epithelial cells (TEC) are the key cell type responsible for orchestrating the fetal development and postnatal function. A single transcription factor, FOXN1, is known to be a critical regulator of multiple aspects of TEC proliferation and function throughout the lifespan. The TEC compartment switches from a fetal/neonatal expansion program to a juvenile homeostasis program, with a key transition point occurring at about 7 days postnatal in mice (P07), and about 4 months of age in humans. Data in mice show that this switch is controlled by the retinoblastoma (RB) pathway, acting at least in part by suppression of Foxn1 gene expression by E2F transcription factors. Mice deficient for multiple RB family members fail to make this switch and continue to expand. The K5.D1 transgenic line, in which CyclinD1 is specifically overexpressed in TEC, mimics this RB loss of function phenotype by activating cyclin-dependent kinases that inhibit RB function. In both RB mutants and K5.D1 transgenics Foxn1 gene expression is elevated, and suppressing Foxn1 expression using a postnatal-specific hypomorphic allele (Foxn1Z/Z) restores the fetal to juvenile switch, normalizing thymus size. We have also shown that Foxn1 regulation of TEC proliferation occurs primarily in MHCIIlo TEC, consistent with preliminary data from the Richie lab that a Sca1-MHCIIlo TEC subset may contain a key proliferating progenitor population during the switch from fetal expansion to juvenile homeostasis. These data suggest that during the perinatal to juvenile transition, RB proteins modulate Foxn1 transcription via E2F transcription factors differentially in specific TEC subsets to ‘put the brakes on’ TEC proliferation, and thus regulate organ size. There is also growing evidence that the neonatal and adult thymi have stage-specific functions that generate distinct T cell populations. As FOXN1 is also known to be a key regulator of TEC differentiation, the changes in how Foxn1 expression is regulated to control TEC proliferation should also have significant impacts on TEC function in the neonatal and adult thymus. We propose three specific aims to test the hypothesis that the RB-dependent changes in Foxn1 gene expression levels during the neonatal period that are essential for establishing organ homeostasis are also required to generate specific microenvironments that are necessary for neonatal-specific organ functions. The goals of this project are to determine: how changes in Foxn1 expression across this transition impact stromal composition changes in mouse, and compare to stromal changes in human thymus; how Foxn1 expression is regulated by the RB pathway during this transition; and how these Foxn1-dependent processes impact immune function.

抽象的 越来越多的证据表明胸腺上皮细胞 (TEC) 是负责协调的关键细胞类型 已知单个转录因子 FOXN1 对胎儿发育和产后功能至关重要。 TEC 隔室在整个生命周期中对 TEC 增殖和功能的多个方面进行调节。 从胎儿/新生儿扩张计划切换到青少年体内平衡计划，有一个关键的过渡点 小鼠（P07）出生后约 7 天发生，人类约 4 个月大时发生。小鼠数据显示。 该开关由视网膜母细胞瘤 (RB) 通路控制，至少部分通过抑制 Foxn1 基因发挥作用 缺乏多个 RB 家族成员的 E2F 转录因子表达无法进行这种转换。 并继续扩增 K5.D1 转基因系，其中 CyclinD1 在 TEC 中特异性过表达， 通过激活抑制 RB 功能的细胞周期蛋白依赖性激酶来模拟 RB 功能丧失表型。 RB突变体和K5.D1转基因Foxn1基因表达升高，而抑制Foxn1表达 使用出生后特异性亚等位基因 (Foxn1Z/Z) 恢复胎儿到青少年的转换，使胸腺正常化 我们还表明 Foxn1 对 TEC 增殖的调节主要发生在 MHCIIlo TEC 中，这是一致的。 根据 Richie 实验室的初步数据，Sca1-MHCIIlo TEC 子集可能包含一个关键的增殖因子 这些数据表明，从胎儿扩张到幼年稳态的转变期间的祖细胞群。 在围产期到青少年的过渡过程中，RB 蛋白通过 E2F 转录因子调节 Foxn1 转录 在特定的 TEC 亚群中存在差异，以“抑制”TEC 增殖，从而调节器官大小。 越来越多的证据表明，新生儿和成人胸腺具有阶段特异性功能，可产生不同的 T 由于 FOXN1 也被认为是 TEC 分化的关键调节因子，因此 Foxn1 的变化方式。 调节表达以控制 TEC 增殖也应该对 TEC 功能产生重大影响 我们提出了三个具体目标来检验 RB 依赖性的假设。 新生儿期 Foxn1 基因表达水平的变化对于建立器官至关重要 还需要稳态来产生新生儿特异性所必需的特定微环境 该项目的目标是确定： Foxn1 表达如何变化。 转变影响小鼠基质成分变化，并与人类胸腺基质变化进行比较； 在此转变过程中 Foxn1 的表达如何受到 RB 途径的调节，以及这些 Foxn1 依赖性如何； 过程影响免疫功能。