Foxf1 Transcription Factor in Development of Pulmonary Capillaries

 描述(申请人提供)：肺泡毛细血管发育不良伴肺静脉错位(ACD/MPV)是一种新生儿和婴儿的致死性先天性疾病，由严重的肺血管发育缺陷引起。由于ACD/MPV婴儿严重的发育缺陷和进行性呼吸功能不全，死亡通常发生在出生后的第一个月内。ACD/MPV患者目前尚无有效的治疗方法，迫切需要新的治疗方法。最近，在40%的ACD/MPV病例中发现了Forkhead Box F1(FOXF1)基因的显性遗传杂合突变。我的实验室以前证明FOXF1转录因子是肺血管发育的关键调节因子。小鼠Foxf1基因的全局缺失是胚胎致死的，而Foxf1缺失等位基因(Foxf1+/-)杂合的小鼠肺毛细血管数量减少，肺发育不良，围产期死亡率增加，这些都是人类ACD/MPV的关键特征。在之前的资助期间，我们建立了内皮特异性缺失Foxf1的小鼠，并证明了FOXF1以细胞自主的方式调节肺内皮细胞中的血管生成和血管内皮生长因子信号。虽然已有42个不同的FOXF1突变与ACD/MPV有关，但这些突变扰乱肺形态发生和功能的分子机制尚不清楚。我们将关注在ACD/MPV中可能具有不同发病机制的五个不同的FOXF1突变。我们的假设是，FOXF1突变通过抑制DNA结合(S52F和G91E突变)、干扰野生型(WT)FOXF1蛋白的功能(Del872-879)或使STAT3信号失活(Y284A和I285Q)来干扰肺血管的发育。在目标1中，我们将FOXF1突变引入原代肺内皮细胞，以确定这些突变扰乱细胞增殖、迁移和血管生成的分子机制。我们还将产生表达一个WT Foxf1等位基因和一个突变Foxf1等位基因的敲入小鼠，模拟ACD/MPV患者的遗传异常。我们将利用这些小鼠来确定FOXF1突变扰乱肺形态发生和功能的分子机制。我们还将使用一种新的小分子化合物，稳定WT FOXF1蛋白，以刺激肺血管的发育，提高小鼠ACD模型的存活率。在目标2中，我们已经使用质谱仪发现FOXF1直接与内皮细胞的关键转录调节因子STAT3蛋白结合。因此，我们将确定FOXF1是否作为STAT3的共激活子来诱导STAT3信号。我们还将测试Y284A和I285Q FOXF1突变破坏FOXF1-STAT3相互作用是否会损害体内肺血管的发育。总之，由于FOXF1和STAT3的减少已经在几种肺部疾病中被报道，我的实验室最近发现的FOXF1稳定化合物可能在治疗目前无法治愈的ACD/MPV和其他与血管功能不全相关的肺部疾病方面具有广泛的治疗应用。

 DESCRIPTION (provided by applicant): Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins (ACD/MPV) is a lethal congenital disorder of neonates and infants caused by severe defects in development of pulmonary vasculature. Due to the severity of developmental defects and progressive respiratory insufficiency in ACD/MPV infants, mortality usually occurs within the first month of birth. There is no effective treatment for ACD/MPV patients, and new therapeutic approaches are greatly needed. Recently, dominantly inherited heterozygous mutations in the Forkhead Box F1 (FOXF1) gene were found in 40% of ACD/MPV cases. My laboratory previously demonstrated that FOXF1 transcription factor is a critical regulator of pulmonary vascular development. Global deletion of the mouse Foxf1 gene is embryonic lethal, whereas mice heterozygous for the Foxf1-null allele (Foxf1+/-) had reduced numbers of pulmonary capillaries, lung hypoplasia and increased perinatal mortality, all key features of human ACD/MPV. During the previous funding period, we generated mice with endothelial-specific deletion of Foxf1 and demonstrated that FOXF1 acts in cell autonomous manner to regulate angiogenesis and VEGF signaling in pulmonary endothelial cells. While 42 distinct FOXF1 mutations have been linked to ACD/MPV, molecular mechanisms by which these mutations perturb pulmonary morphogenesis and function remain unknown. We will focus on five distinct FOXF1 mutations that may have different pathogenesis in ACD/MPV. Our hypothesis is that FOXF1 mutations disrupt lung vascular development by inhibiting DNA binding (S52F and G91E mutations), interfering with function of wild type (WT) FOXF1 protein (Del872-879) or inactivating STAT3 signaling (Y284A and I285Q). In Aim 1, we will introduce the FOXF1 mutations into primary lung endothelial cells to determine molecular mechanisms by which these mutations disrupt cellular proliferation, migration and angiogenesis. We will also generate knock-in mice expressing one WT Foxf1 allele and one mutant Foxf1 allele, mimicking genetic abnormalities in ACD/MPV patients. We will use these mice to identify molecular mechanisms by which the FOXF1 mutations perturb pulmonary morphogenesis and function. We will also use a novel small molecule compound, which stabilizes WT FOXF1 protein, to stimulate development of pulmonary vasculature and improve survival in mouse ACD models. In Aim 2, using mass spectrometry we have already found that FOXF1 directly binds to the STAT3 protein, a key transcriptional regulator of endothelial cells. Thus, we will determine if FOXF1 functions as a co- activator of STAT3 to induce STAT3 signaling. We will also test whether disruption of FOXF1-STAT3 interactions by Y284A and I285Q FOXF1 mutations impairs pulmonary vascular development in vivo. Altogether, since reduced FOXF1 and STAT3 have been reported in several lung diseases, FOXF1-stabilizing compounds, which were recently identified in my laboratory, could have broad therapeutic applications for treatment of currently incurable ACD/MPV and other lung diseases associated with vascular insufficiency.