The Forkhead Transcription Factor, FOXO1, and its Role in Pituitary Gland Develop

描述(由申请人提供)：先天性激素缺乏症很常见，大约每4,000名活产儿中就有一名发生。脑下垂体激素缺乏可包括单一激素缺乏(单独的激素缺乏)或几种激素(综合垂体激素缺乏)。缺乏脑下垂体前叶激素不会影响胎儿的生存能力，但对于出生后的存活、性腺分化和胎儿甲状腺的成熟都是必需的。转录因子PITX1、PITX2、HESX1、LHX3、LHX4、TPIT、PROP1和PIT1的损伤导致小鼠和人类的联合垂体激素缺乏症。然而，这些转录因子的突变只占人类先天性激素缺乏症的一小部分。为了确定导致人类先天性激素缺乏的其他因素，我们正在研究叉头转录因子FOXO1，它对几个器官的正常发育非常重要。由于血管缺陷，Foxo1基因敲除的小鼠在胚胎第10.5天会导致胚胎死亡。我们的目的是研究FOXO1在先天性垂体激素缺乏症中的作用。我们假设，消除脑下垂体中的FOXO1将导致脑下垂体的增殖和组织失调，从而导致激素产生的损失和/或产生激素的细胞类型的错误指定。这一假设基于以下观察结果。首先，我们的初步结果显示，FOXO1存在于未分裂的垂体细胞的细胞核中，从e14.5开始，这些细胞开始分化。其次，FOXO1抑制胰腺2-细胞、成肌细胞、脂肪细胞和内皮细胞的增殖并调节其分化和迁移。为了验证这一假设，我们提出了三个特定的目标：特定的目标1.确定FOXO1在发育过程中的脑垂体细胞特异性。我们将在e18.5对小鼠胚胎组织进行标记五种垂体细胞类型的激素的免疫组织化学和FOXO1的免疫组织化学。具体目的2.探讨Foxo1在脑下垂体发育和功能中的需要。我们将分析已经在脑下垂体中消除了Foxo1表达的小鼠胚胎的脑垂体腺(Foxo1 Pit/-)。我们将评估垂体的形态，分析垂体前叶激素的产生，并测量细胞的增殖和凋亡。具体目的3.将Foxo1置于脑下垂体发育控制的遗传层次中。我们将对Foxo1 PIT/-小鼠胚胎进行免疫组织化学，以寻找正常垂体发育所需的基因。这些研究产生的知识将通过识别先天性垂体激素缺乏症的候选基因和增加我们关于叉头因子突变如何导致出生缺陷的知识来进一步推动这一领域。我们在叉头转录因子功能和脑下垂体发育方面的专业知识使我们处于解决这一问题的独特情况下。 与公众健康相关：脑下垂体激素对于出生后的生存以及性腺和甲状腺的正常发育是必不可少的。叉头转录因子FOXO1对肌肉、血管和胰腺的正常发育和功能是必不可少的。FOXO1在脑下垂体发育过程中的定位模式表明，FOXO1具有抑制细胞分裂和调节细胞分化的作用。我们的目的是通过分析垂体腺中缺失FOXO1的小鼠的垂体表型，来确定FOXO1对正常垂体腺发育的需求。

DESCRIPTION (provided by applicant): Congenital hormone deficiencies are common, occurring in approximately one in 4,000 live births. Pituitary hormone deficiency can consist of loss of a single hormone (isolated hormone deficiency) or several hormones (combined pituitary hormone deficiency). Absence of anterior pituitary hormones does not interfere with fetal viability, but are required for survival after birth, gonadal differentiation, and maturation of the fetal thyroid. Lesions in the transcription factors PITX1, PITX2, HESX1, LHX3, LHX4, TPIT, PROP1 and PIT1 lead to combined pituitary hormone deficiency in mice and humans. However mutations in these transcription factors account for only a fraction of congenital hormone deficiencies in humans. To identify additional factors that contribute to human congenital hormone deficiencies, we are investigating the forkhead transcription factor, FOXO1, which is important for the normal development of several organs. Mouse knockout models for Foxo1 result in embryonic lethality at embryonic day (e)10.5 due to vascular defects. Our objective is to investigate the contributions of FOXO1 to congenital pituitary hormone deficiency. We hypothesize that eliminating FOXO1 in the pituitary will cause hyperplasia and misorganization of the pituitary gland resulting in loss of hormone production and/or mis-specification of hormone-producing cell types. This hypothesis is based on the following observations. First, our preliminary results show that FOXO1 is present in nuclei of non-dividing pituitary cells starting at e14.5 when these cells are beginning to differentiate. Secondly, FOXO1 inhibits proliferation and regulates differentiation and migration of pancreatic 2-cells, myoblasts, adipocytes, and endothelial cells. To test this hypothesis we propose three specific aims: Specific Aim 1. Determine the pituitary cell specificity for FOXO1 during development. We will perform immunohistochemistry for the hormones that mark the five pituitary cell types in combination with immunohistochemistry for FOXO1 on mouse embryonic tissue at e18.5. Specific Aim 2. Investigate the requirement for Foxo1 in pituitary gland development and function. We will analyze pituitary glands from mouse embryos that have had Foxo1 expression eliminated in the pituitary gland (Foxo1 pit/-). We will assess pituitary morphology, analyze anterior pituitary hormone production, and measure cell proliferation and apoptosis. Specific Aim 3. Place Foxo1 in the genetic hierarchy of pituitary gland developmental control. We will perform immunohistochemistry on Foxo1 pit/- mouse embryos for genes that are required during normal pituitary development. The knowledge generated by these studies will further this field by identifying a candidate gene for congenital pituitary hormone deficiency and by adding to our knowledge of how forkhead factor mutations cause birth defects. Our expertise in both forkhead transcription factor function and pituitary development places us in a unique situation to address this problem. PUBLIC HEALTH RELEVANCE: Pituitary hormones are essential for survival after birth and for the normal development of gonads and thyroid gland. The forkhead transcription factor, FOXO1, is essential for the normal development and function of muscle, blood vessels, and pancreas. The pattern of FOXO1 localization in the pituitary gland during development suggests a role for inhibiting cell division and regulating cell differentiation. Our objective is to determine the requirement of FOXO1 for normal pituitary development by analyzing the pituitary phenotype in mice that lack FOXO1 in the pituitary gland.