Molecular mechanisms and epigenetic signatures that specify thymus fate

决定胸腺命运的分子机制和表观遗传特征

• 批准号: 9436424
• 负责人: Nancy R Manley
• 金额: $ 9.2万
• 依托单位: UNIVERSITY OF TX MD ANDERSON CAN CTR
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9436424
• 关键词: Alleles; BMP2 gene; BMP4; Bioinformatics; Candidate Disease Gene; Cells; Data; Development; Dorsal; Ectopic Expression; Embryology; Endoderm; Ensure; Epigenetic Process; Epithelial; FGF8 gene; Fetal Development; Fibroblast Growth Factor; GCM2 gene; Gene Expression; Genetic; Genetic Transcription; Grant; Mediating; Mesenchymal; Messenger RNA; Modeling; Molecular; Molecular Biology; Mus; Organ; Parathyroid gland; Pattern; Pharyngeal pouch; Refractory; Regulation; Role; SHH gene; Signal Pathway; Signal Transduction; Specific qualifier value; T-Cell Development; Testing; Thymic epithelial cell; Thymus Gland; To specify; Transgenes; Work; aged; base; experimental study; fetal; genome-wide; histone methylation; loss of function; network models; novel strategies; prevent; progenitor; programs; public health relevance; support network; transcription factor

DESCRIPTION (provided by applicant): Despite the critical role of the thymus in T cell development, the mechanisms required to specify initial thymus fate during fetal development are not known. Understanding these mechanisms will facilitate the development of strategies to generate functional thymus organs in culture, and to rejuvenate the aged, involuted thymus. Thymus fate is specified in the ventral 3rd pharyngeal pouch (pp) endoderm between E9.5 and E11 during mouse fetal development; the dorsal domain of this pouch gives rise to the parathyroid glands. As the 3rd pp must be patterned into two distinct cell fates, mechanisms must be in place to ensure that both organs are properly specified. Previous work from our labs and others have implicated BMP2/4 and FGF8/10 signals in establishing thymus fate, while SHH signaling is required for parathyroid fate. These two signaling pathways appear to act in opposition; however, the mechanisms by which they interact with each other and regulate organ-specific transcriptional networks remain to be established. Recent collaborative experiments from the Richie and Manley labs suggest that the transcription factor TBX1 is a key regulator of the decision between thymus and parathyroid cell fate. We have shown that Tbx1 is expressed in the parathyroid domain of the 3rd pp endoderm, but not in the ventral thymus fated domain, and that ectopic TBX1 is sufficient to suppress Foxn1 expression. Based on our preliminary data we generated a testable model of thymus fate specification in which suggest that FGF8 and BMP4 are positive regulators, whereas SHH and Tbx1 antagonize thymus development. This project uses a novel approach to decipher the molecular network that specifies endodermal progenitors to a thymus fate, combining embryology, genetics, molecular biology, bioinformatics, and epigenetics. The results will provide a rationale basis for programming early progenitors to generate a functional thymic epithelial cell network that supports thymopoiesis. We will test our model in the following Specific Aims. Aim 1. Test the hypothesis that multiple mechanisms suppress Tbx1 expression in the ventral domain of 3rd pp endoderm, and that this suppression is required to establish thymus fate. Aim 2. Test whether the ability of TBX1 to inhibit thymus differentiation is temporally restricted, and identify the mechanism by which ectopic TBX1 and/or SHH signaling blocks thymus fate. Aim 3. Test the hypothesis that progressive establishment of organ-specific epigenetic signatures determines thymus fate, and depends on cooperation between the BMP and FGF signaling pathways

描述（由申请人提供）：尽管胸腺在 T 细胞发育中起着关键作用，但在胎儿发育过程中指定初始胸腺命运所需的机制尚不清楚。了解这些机制将有助于制定在培养物中生成功能性胸腺器官的策略，并使老化、退化的胸腺恢复活力。在小鼠胎儿发育过程中，胸腺命运在 E9.5 和 E11 之间的腹侧第三咽袋 (pp) 内胚层中被指定；该袋的背侧区域产生甲状旁腺。由于第三个 pp 必须被模式化为两种不同的细胞命运，因此必须建立适当的机制来确保两个器官都得到正确指定。我们实验室和其他实验室之前的工作表明，BMP2/4 和 FGF8/10 信号与确定胸腺命运有关，而 SHH 信号是甲状旁腺命运所必需的。这两种信号传导途径似乎相反。然而，它们相互作用和调节器官特异性转录网络的机制仍有待建立。 Richie 和 Manley 实验室最近的合作实验表明，转录因子 TBX1 是决定胸腺和甲状旁腺细胞命运的关键调节因子。我们已经证明，Tbx1 在第 3 pp 内胚层的甲状旁腺结构域中表达，但不在腹侧胸腺命运结构域中表达，并且异位 TBX1 足以抑制 Foxn1 表达。根据我们的初步数据，我们生成了一个可测试的胸腺命运规范模型，其中表明 FGF8 和 BMP4 是正调节因子，而 SHH 和 Tbx1 拮抗胸腺发育。该项目结合胚胎学、遗传学、分子生物学、生物信息学和表观遗传学，采用一种新颖的方法来破译指定内胚层祖细胞与胸腺命运相关的分子网络。这些结果将为编程早期祖细胞生成支持胸腺生成的功能性胸腺上皮细胞网络提供理论基础。我们将在以下具体目标中测试我们的模型。目标 1. 检验以下假设：多种机制抑制第 3 pp 内胚层腹侧区域的 Tbx1 表达，并且这种抑制是确定胸腺命运所必需的。目标 2. 测试 TBX1 抑制胸腺分化的能力是否受到暂时限制，并确定异位 TBX1 和/或 SHH 信号传导阻断胸腺命运的机制。目标 3. 检验以下假设：器官特异性表观遗传特征的逐步建立决定胸腺命运，并且取决于 BMP 和 FGF 信号通路之间的合作