Identification of Loci Governing Craniofacial Abnormalities Using a Natural Model

描述(由申请人提供)：导致人类牙科和颅面部疾病全谱的确切分子和遗传机制尚不清楚。受影响的个体并不是孤立地经历头面部骨骼的异常，而是经常表现出共生缺陷。有害的、多效性基因座在导致这些共病特征中的作用仍然很大程度上尚不清楚。为了解决这个问题，我们试图开发一个自然的模式系统，Astianax micianus，用于强大的基因组分析。这个模型系统由表观(表面)和地下(洞穴)形式组成，表现出许多“退化”的表型。这些症状包括头面部骨骼表型(真皮骨碎裂)和牙齿畸形(异位上颌牙)，并伴有严重的色素缺失。我的研究计划的长期目标是识别并从功能上验证导致我们的自然模型系统--墨西哥冬虫夏草--的这种颅面畸形频谱的基因座。这个R03应用程序代表着朝着实现这一目标迈出的重要一步，它有两个具体的目标：1)在密集的Astianax连锁图谱的背景下确定头面部异常和色素缺陷的遗传基础；2)利用组织特定的全基因组转录组图谱来识别控制头面部改变的候选基因。这项研究的中心假设是，自然界中存在的多种退化表型是通过相同的或紧密相连的多效性基因座产生的。拟议的项目将利用一个大型连锁测绘鱼类谱系的高分辨率显微CT X射线成像。这种非侵入性的方法有助于共同分析可能受相同基因调控因素影响的其他性状。初步研究表明，Astianax的12个头面部和牙齿特征具有遗传基础，与其他非骨骼特征(例如，视力丧失、色素沉着减少)有关的许多基因座重叠。这项研究试图通过加速发现与这一表型星座有关的候选基因，为未来的应用奠定基础。总而言之，该项目代表了连锁图谱、下一代测序方法和高分辨率表型分析的创新集成，以确定颅面和牙齿异常的遗传基础。这项拟议的研究具有重要意义，因为它将使随后在R01水平上进行的最终研究成为可能，并且是一系列研究的第一步，这些研究旨在1)揭示导致颅面缺陷与相关共病表型的基因的确切功能作用，以及2)阐明脊椎动物正常的颅面和牙齿发育的机制。

DESCRIPTION (provided by applicant): The precise molecular and genetic mechanisms leading to the complete spectrum of dental and craniofacial disorders in humans remain unknown. Rather than experiencing aberrations of the craniofacial skeleton in isolation, affected individuals frequently manifest co-occurring deficits. The role of deleterious, pleiotropic loci in causing these co-morbid features remains largely unexplored. To approach this problem, we seek to develop a natural model system, Astyanax mexicanus, for powerful genomic analyses. This model system consists of epigean (surface) and subterranean (cave-dwelling) forms that demonstrate numerous "degenerative" phenotypes. These include craniofacial bone phenotypes (dermal bone fragmentation) and dental aberrations (an ectopic maxillary tooth) co-occurring with severe pigmentation defects. The long term goal of my research program is to identify and functionally validate the loci causing this spectrum of craniofacial abnormalities in our natural model system, Astyanax mexicanus. This R03 application, which represents a significant step towards attaining this goal has two specific aims: 1) define the genetic bases for craniofacial abnormalities and pigmentation defects in the context of a densely-populated Astyanax linkage map, and 2) identify candidate genes governing craniofacial alterations utilizing tissue-specific whole genome transcriptome profiling. The central hypothesis of this research is that multiple degenerative phenotypes present in the natural world arise through the same, or closely linked, pleiotropic loci. The proposed project will utilize high-resolution microCT X-ray imaging of a large linkage-mapping fish pedigree. This non-invasive approach facilitates co-analysis of additional traits that may be influenced by the same genetic regulators. Preliminary studies indicate a genetic basis for 12 craniofacial and dental features in Astyanax, with overlap of numerous loci involved in other non-skeletal features (e.g., vision loss, pigmentation reduction). This study seeks to lay the groundwork for future applications by accelerating discovery of candidate genes involved in this constellation of phenotypes. In sum, this project represents an innovative integration of linkage mapping, next-generation sequencing approaches, and high-resolution phenotypic analyses to determine the genetic basis for craniofacial and dental abnormalities. The proposed research is significant because it will enable subsequent definitive studies at the R01 level, and is the first step in a continuum of research designed to 1) inform the precise functional role of genes causing craniofacial defects with associated co-morbid phenotypes, and 2) clarify mechanisms governing normal craniofacial and dental development in vertebrates.