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促进我们对红细胞(RBC)和遗传性贫血的发病机制的了解。在这项提案中，我们将继续使用这种强大的表型驱动的方法来发现和阐明哺乳动物的基因功能。具体目标是：目的1.SCAT和Nan的定位克隆。小鼠隐性突变SCAT(严重合并贫血和血小板减少)和显性突变NAN(新生儿贫血)表现出严重贫血表型，这是由于造血干细胞固有的缺陷造成的。遗传图谱将SCAT和NAN定位在8号染色体上的独特位置，与之前发现的任何小鼠突变无关。因此，我们假设，Nan和SCAT代表了以前没有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)鉴定编码的mRNA和蛋白质产物，以及(C)进一步鉴定scat和nan的血液学表型。目的2.新突变型Sph等位基因的特征。先前已经描述了5种等位基因隐性突变(球形细胞增多症，Sph)，并由于1-Spectrin基因(SpNa1)的缺陷而导致严重的溶血性贫血。我们最近发现了另外两个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的新的相互作用。我们将(A)完成sph3J和sph4J的表型，(B)通过表征与已知膜骨架成分的相互作用来确定各自的1-Spectrin突变所引起的功能缺陷，以及(C)确定膜内新的Spectrin相互作用。 与公共卫生相关：小鼠和人类的遗传性贫血具有共同的病因。因此，识别小鼠贫血模型中的主要基因缺陷直接关系到人类的健康，将增进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.