Genetic Architecture of Hsp90-buffered variation

描述（由申请人提供）：由于涉及大量的遗传和环境因素及其复杂的相互作用，我们目前对复杂的人类疾病（如癌症）不易感的基因的了解有限。癌症的特征是通过调节细胞生长、死亡或DNA维持所需的途径发出异常信号。这些途径中的单基因突变导致罕见的癌症，但对信号传导影响不大的未知基因的常见多态性等位基因是大多数癌症的原因。为了找到这些基因，人类研究是困难的，昂贵的，并且偏向于先前已知的生物机制和大作用的基因。另一种方法是在模式生物中找到保守信号通路的修饰因子，然后研究它们与疾病相关的人类同源变异。Hsp90应激蛋白支持许多保守的肿瘤抑制因子、癌基因和细胞周期调节因子的活性。当果蝇Hsp90受限时，多基因变异对发育的影响表现为菌株特异性异常。我们认为，发育上的新颖性是由于自然遗传变异影响了由Hsp90靶点决定的发育、调节和生长控制途径的信号强度。因此，果蝇中影响hsp90依赖性信号通路的自然变异网络模拟了人类癌症易感性的信号变异结构，并具有推动发展进化的潜力。为了鉴定天然的hsp90缓冲多态性并将其置于通路中，我们使用hsp90依赖性眼睛异常的实验室选择，在高比例的受影响果蝇中产生复制的“变形眼”系。将具有正常眼的自交系野生型遗传背景与选择系杂交，构建了1400多个重组等基因作图系（克隆）。对于每个重组品系，平均有50只具有相同重组基因型的果蝇进行性状外显率（受影响的概率）评分，并保存下来进行基因分型。我们的具体目标是1)通过SQTL（数量性状抑制位点）和缺失定位来定位变形眼的多态性，以验证变形眼的遗传结构在复制系中出现的不同观点。2)克隆变形眼多态性野生型等位基因作为性状外显率的抑制基因，确定隐性多态性是存在于Hsp90靶基因还是存在于影响较小的外周基因。3)明确眼畸形病理的发育过程和通路，将hsp90缓冲变异纳入生物学背景。我们期望这项研究将确定保守的Hsp90靶通路和影响其功能的自然多态性基因的扩展网络。

DESCRIPTION (provided by applicant): Our present knowledge of the genes involved insusceptibilities to complex human diseases such as cancer is limited due to the large number of genetic and environmental factors involved and their complex interactions. Cancer is characterized by aberrant signaling through pathways required for regulated cell growth, death, or DNA maintenance. Single gene mutations in these pathways cause rare cancers, but common polymorphic alleles of unknown genes with modest effects on signaling are responsible for most cancers. To find these genes, human studies are difficult, costly, and biased toward previously known biological mechanisms and genes of large effect. An alternative approach is to find modifiers of conserved signaling pathways in model organismsand then study their human homologs variants associated with disease. The Hsp90 stress protein supports the activities of many conserved tumor suppressors, oncogenes, and cell cycle regulators. When Drosophila Hsp90 is limiting, polygenic variation with potent effects on development is expressed as strain specific abnormalities. We believe that the developmental novelties result from natural genetic variation affecting the strength of signaling through the developmental, regulatory, and growth control pathways determined by Hsp90 targets. Thus, a network of natural variation influencingHsp90-dependent signaling pathways in flies models the architecture of signaling variation for cancer predisposition in humans, and has the potential to drive the evolution of development. To identify natural Hsp90-buffered polymorphisms and place them in pathways we used laboratory selection for Hsp90-dependent eye abnormalities to generate replicate 'deformed eye' lines with a high fraction of affected flies. An inbred wild-type genetic background with normal eyes was crossed into the selection lines to construct over 1,400 recombinant isogenic mapping lines (clones). For each recombinant line, on average 50 flies having identical recombinant genotypes were scored for trait penetrance (probability affected) and saved for genotyping. Our specific aims are to 1) localize deformed eye polymorphisms by SQTL (Suppressor of Quantitative Trait Loci) and deletion mapping to test the idea that varied genetic architectures for deformed eye arose in the replicate lines. 2) Clone the wild-type alleles of deformed eye polymorphisms as suppressors of trait penetrance to determine whether hidden polymorphisms reside in Hsp90 targets or in peripheral genes of small effect. 3) Identify developmental processes and pathways responsible for the pathology of deformed eye to bring Hsp90-buffered variation into biological context. We expect this research will identify conserved Hsp90 target pathways and an extended network of naturally polymorphic genes that influence their function.