Genetic Identification of Novel Genes Critical in Erythropoiesis

描述（由申请人提供）：遗传定义的小鼠模型有助于推进我们对红细胞（RBC）和遗传性贫血发病机制的认识。在这个建议中，我们将继续这种强大的表型驱动的方法来发现基因和阐明哺乳动物基因功能。具体目标是：目标1。scat和Nan的定位克隆。隐性小鼠突变scat（重度联合贫血和血小板减少症）和显性突变Nan（新生儿贫血）显示由造血干细胞固有缺陷引起的重度贫血表型。遗传作图将scat和Nan定位于8号染色体上的独特位置，与任何先前确定的小鼠突变无关。因此，我们假设Nan和scat代表了以前未被认为显著影响血液形成的新基因。在这里，我们将（a）定位克隆scat和Nan基因，（B）表征编码的mRNA和蛋白质产物，和（c）进一步表征scat和Nan血液学表型。目标2.新突变sph等位基因的特征。先前已经描述了由于1-血影蛋白基因（Spna 1）缺陷导致的5种等位基因隐性小鼠突变（球形红细胞增多症，sph）伴严重溶血性贫血。我们最近发现了2个额外的sph等位基因，sph 3 J和sph 4J，与先前描述的等位基因相比，它们显示出独特的表型特征。因此，我们假设，B13 J和B14 J破坏RBC膜骨架内的新的相互作用。我们将（a）完成sph 3 J和sph 4 J的表型分析，（B）通过表征与已知膜骨架成分的相互作用来鉴定相应1-血影蛋白突变引起的功能缺陷，以及（c）鉴定膜内新型血影蛋白相互作用。 与公共卫生的相关性：小鼠和人的遗传性贫血具有共同的病因。因此，在小鼠贫血模型中鉴定主要基因缺陷与人类健康直接相关，将增强我们对血液形成的理解，并为血液病理学提供新的诊断和治疗靶点。

DESCRIPTION (provided by applicant): Genetically defined mouse models have been instrumental in advancing our knowledge of the red blood cell (RBC) and the pathogenesis of inherited anemia. In this proposal, we will continue this powerful phenotype- driven approach to gene discovery and elucidation of mammalian gene function. The specific aims are: Aim 1. Positional cloning of scat and Nan. The recessive mouse mutation, scat (severe combined anemia and thrombocytopenia) and the dominant mutation, Nan (Neonatal anemia), display a severe anemia phenotype resulting from defects intrinsic to hematopoietic stem cells. Genetic mapping localized both scat and Nan to unique positions on chromosome 8 not associated with any previously identified mouse mutation. We hypothesize, therefore, that Nan and scat represent novel genes not previously recognized as significantly impacting blood formation. Here, we will (a) positionally clone the scat and Nan genes, (b) characterize the encoded mRNA and protein products, and (c) further characterize the scat and Nan hematological phenotypes. Aim 2. Characterization of novel mutant sph alleles. Five allelic recessive mouse mutations (spherocytosis, sph) with severe hemolytic anemia due to defects in the 1-spectrin gene (Spna1) have been previously described. We recently identified 2 additional sph alleles, sph3J and sph4J, that display unique phenotypic characteristics compared to the previously described alleles. Hence, we hypothesize that sph3J and sph4J disrupt novel interactions within the RBC membrane skeleton. We will (a) complete the phenotyping of sph3J and sph4J, (b) identify functional deficits incurred by the respective 1-spectrin mutations by characterizing interactions with known membrane skeleton components, and (c) identify novel spectrin interactions within the membrane. Relevance to Public Health: Inherited anemias in mouse and man share common etiologies. Thus, identifying the primary gene defect in mouse models of anemia has direct relevance to human health, will enhance our understanding of blood formation, and provide novel diagnostic and therapeutic targets for hematological pathologies.