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名活产婴儿中就有一名。垂体激素缺乏症可以包括单一激素（孤立性激素缺乏症）或几种激素（联合垂体激素缺乏症）的损失。垂体前叶激素的缺乏不会影响胎儿的生存能力，但对出生后的存活、性腺分化和胎儿甲状腺的成熟是必需的。转录因子PITX 1、PITX 2、HESX 1、LHX 3、LHX 4、TPIT、PROP 1和PIT 1中的病变导致小鼠和人类的垂体激素联合缺乏。然而，这些转录因子的突变仅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症的其他因素，我们正在研究叉头转录因子FOXO 1，它对几个器官的正常发育很重要。Foxo 1基因敲除小鼠模型在胚胎第10.5天由于血管缺陷导致胚胎死亡。我们的目的是探讨FOXO 1在先天性垂体激素缺乏症中的作用。我们假设，消除垂体中的FOXO 1将导致垂体的增生和组织紊乱，导致激素产生的损失和/或错误指定产生激素的细胞类型。这一假设基于以下观察。首先，我们的初步结果表明，FOXO 1是存在于细胞核的非分裂垂体细胞开始在e14.5时，这些细胞开始分化。其次，FOXO 1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，我们提出了三个具体目标：具体目标1。确定发育过程中垂体细胞对FOXO 1的特异性。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FOXO 1的免疫组织化学。具体目标2。探讨Foxo 1在垂体发育和功能中的需求。我们将分析来自小鼠胚胎的垂体腺，这些胚胎在垂体腺中消除了Foxo 1表达（Foxo 1 pit/-）。我们将评估垂体形态，分析垂体前叶激素的产生，并测量细胞增殖和凋亡。具体目标3。将Foxo 1置于脑垂体发育控制的遗传层次中。我们将对Foxo 1 pit/-小鼠胚胎进行免疫组化，以确定正常垂体发育过程中所需的基因。这些研究所产生的知识将进一步这一领域确定一个候选基因的先天性垂体激素缺乏症，并通过增加我们的知识叉头因子突变如何导致出生缺陷。我们在叉头转录因子功能和垂体发育方面的专业知识使我们处于解决这个问题的独特位置。 公共卫生相关性：垂体激素对出生后的生存以及性腺和甲状腺的正常发育至关重要。叉头转录因子FOXO 1对肌肉、血管和胰腺的正常发育和功能至关重要。在发育过程中，FOXO 1在脑垂体中的定位模式表明其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中缺乏FOXO 1的小鼠的垂体表型来确定FOXO 1对正常垂体发育的需求。

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.