PAX9, ribosome biogenesis, and congenital disease

项目摘要/摘要 背景和中心假设：脊椎病是由制造过程中的中断引起的 核糖体，负责合成所有细胞蛋白质的复杂分子机器。当一个人可能 预计在这样一个基本过程中的缺陷会导致一个不能存活的有机体，这种紊乱反而表现在 特定于组织的体征和症状。在核糖体病Treacher Collins综合征中，这种组织特异性 应激敏感型神经脊细胞核仁应激反应引起的颅面部缺陷。 配对盒9(PAX9)基因的突变导致超过6颗恒牙或缺牙的丢失， 以及头面部畸形和脱发。这些症状与核糖体病相似， 特雷奇·柯林斯综合征。人MCF10A细胞中全基因组siRNA筛选所需的蛋白质 核糖体的产生揭示了RNA聚合酶II(POL II)转录因子的意想不到的作用， PAX9，在人类核糖体生物发生中。初步结果表明，PAX9的耗尽会导致 核糖体前RNA(Pre-rRNA)处理以及编码基因子集转录减少 核仁蛋白。我假设PAX9通过促进核糖体的发生间接改变哺乳动物核糖体的生物发生。 转录在细胞核仁中制造核糖体所需的一个或多个这些基因的转录我提议 PAX9基因突变患者的头面部畸形和缺牙与PAX9基因的S有关 在核糖体生物发生中的关键作用。特定目标：特定目标1将确认PAX9蛋白是必需的 用于编码核仁蛋白的候选基因的转录。我会确认北方的污点 表型与PAX9‘S转录的候选基因有直接关系。我还将演示PAX9结合 直接作用于并调节候选基因的转录。具体目标2将测试在多大程度上 发育中胚胎中PAX9缺失或突变将头面部畸形与核糖体联系起来 生物发生学。首先，我将建立热带非洲爪哇的模型系统，研究PAX9对两者的影响 颅面发育与核糖体生物发生。然后我将测试候选基因在多大程度上 具体目标1概括了在PAX9耗尽时看到的缺陷。

PROJECT SUMMARY/ABSTRACT BACKGROUND AND CENTRAL HYPOTHESIS: Ribosomopathies are caused by disruptions in making ribosomes, the intricate molecular machines responsible for synthesizing all cellular proteins. While one might expect defects in such an essential process to result in an inviable organism, such disorders instead manifest in tissue-specific signs and symptoms. In the ribosomopathy Treacher Collins syndrome, this tissue specificity manifests in craniofacial defects arising from the nucleolar stress response in stress-sensitive neural crest cells. Mutations in the Paired box 9 (PAX9) gene result in the loss of more than six permanent teeth, or oligodontia, as well as craniofacial dysmorphology and hair loss. These symptoms are similar to those of the ribosomopathy, Treacher Collins syndrome. A genome-wide siRNA screen in human MCF10A cells for proteins required for the production of ribosomes revealed an unexpected role for the RNA Polymerase II (POL II) transcription factor, PAX9, in human ribosome biogenesis. Preliminary results have shown that PAX9 depletion results in defects in pre-ribosomal RNA (pre-rRNA) processing as well as in decreased transcription of a subset of genes that encode nucleolar proteins. I hypothesize that PAX9 alters mammalian ribosome biogenesis indirectly by promoting the transcription of one or more of these genes required for making ribosomes in the cell nucleolus. I propose that the craniofacial dysmorphology and oligodontia seen in humans with PAX9 mutations is connected to PAX9’s crucial role in ribosome biogenesis. SPECIFIC AIMS: Specific Aim 1 will confirm that the PAX9 protein is required for the transcription of candidate genes encoding nucleolar proteins. I will confirm that the northern blot phenotype is directly related to PAX9’s transcription of the candidates. I will also demonstrate that PAX9 binds directly to and regulates the transcription of the candidate genes. Specific Aim 2 will test the extent to which PAX9 depletion or mutation in a developing embryo connects craniofacial dysmorphology to ribosome biogenesis. First, I will establish Xenopus tropicalis as a model system for studying the effects of PAX9 on both craniofacial development and ribosome biogenesis. I will then test the extent to which the candidate genes from Specific Aim 1 recapitulate the defects seen upon PAX9 depletion.