Genetic Identification of Novel Genes Critical in Erythropoiesis

描述（由申请人提供）：基因定义的小鼠模型有助于提高我们对红细胞（RBC）和遗传性贫血发病机制的认识。在本提案中，我们将继续这种强大的表型驱动的方法，以基因发现和阐明哺乳动物基因功能。具体目标是：目标1。scat和Nan的位置克隆。隐性小鼠突变scat（严重合并性贫血和血小板减少症）和显性突变Nan（新生儿贫血）表现出由造血干细胞固有缺陷引起的严重贫血表型。遗传图谱将scat和Nan定位在8号染色体上的独特位置，与任何先前发现的小鼠突变无关。因此，我们假设Nan和scat代表了以前未被认为对血液形成有显著影响的新基因。在这里，我们将(a)定位克隆scat和Nan基因，(b)表征编码的mRNA和蛋白产物，以及(c)进一步表征scat和Nan血液学表型。目标2。新突变sph等位基因的鉴定。由于1-谱蛋白基因（Spna1）的缺陷，五种等位基因隐性小鼠突变（球形细胞增生症，sph）导致了严重的溶血性贫血。我们最近发现了两个额外的sph等位基因，sph3J和sph4J，与之前描述的等位基因相比，它们表现出独特的表型特征。因此，我们假设sph3J和sph4J破坏了红细胞膜骨架内新的相互作用。我们将(a)完成sph3J和sph4J的表型分型，(b)通过表征与已知膜骨架组分的相互作用来鉴定各自的1-spectrin突变引起的功能缺陷，以及(c)鉴定膜内新的spectrin相互作用。

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.