Genetic Determinants of Erythrocyte Hydration

描述(申请人提供)：嵌入细胞膜的转运蛋白功能的变化与镰状细胞性贫血、Hb CC和SC疾病的红细胞脱水、遗传性球形红细胞增多症和干细胞性红细胞增多症有关。脱水的细胞最有可能产生镰刀状并产生血管闭塞；因此，正在开发特殊的治疗方法来减少体内的脱水。这些通路活动的重要生理调节因素/决定因素尚不清楚，因此阻碍了对更有可能经历细胞脱水和血管闭塞的患者亚群的识别。我们建议在小鼠和最终的人类红细胞中识别影响离子转运途径和细胞水合功能的重要生理学基因。我们将使用近亲交配的小鼠品系来识别数量链基因(QTL)，并最终确定调节红细胞水合和运输的个别基因。我们已经确定了细胞水合作用差异很大的近交系小鼠：从适当的杂交组合中，将进行QTL分析，以专注于与不同表型相关的基因组区域，并确定涉及的基因(S)。我们还提出了11个正常近交系小鼠红细胞离子含量和运输特性的详细表型特征，重点是三种已知的介导脱水的途径(Gardos通道、K-CI共转运和Na-K泵)。这些菌株被广泛使用，具有丰富的遗传和表型信息。我们将建立信息性交叉，以确定与运输活动中有意义的差异相关的特定QTL。小鼠体内影响红细胞水合和离子运输的基因的定义将启发镰刀鼠模型的探索，并将允许使用敲入/敲除实验来测试候选基因。最终目的是在未来的研究中验证小鼠候选基因与患者的适当关联研究。我们预计，这些研究将导致识别与镰状细胞综合征和其他贫血的病理生理学相关的新基因，以及潜在的新治疗靶点、疾病严重程度的标记物和特定治疗的易感性指标。

DESCRIPTION (provided by applicant): Changes in the function of transporters embedded into the cell membrane have been associated with erythrocyte dehydration in sickle cell anemia, Hb CC and SC diseases, hereditary spherocytosis and xerocytosis. Dehydrated cells are the most likely to sickle and produce vaso-occlusion; thus, specific therapies are being developed to diminish dehydration in vivo. The physiologically important regulators/determinants of activity of these pathways are not known, thus impeding the identification of subsets of patients more likely to experience cell dehydration and vaso-occlusion. We propose to identify physiologically important genes affecting the function of ion transport pathways and cell hydration in mouse and eventually human erythrocytes. We will use inbred mouse strains to identify quantitative tract loci (QTLs) and ultimately individual genes that modulate red cell hydration and transport. We have already identified inbred mouse strains with large differences in cell hydration: from the appropriate crosses, QTL analysis will be performed to focus on areas of the genome associated with the different phenotype, and identify the gene(s) involved. We also propose a detailed phenotypic characterization of the erythrocyte ion content and transport properties, focused on three pathways known to mediate dehydration (Gardos channel, K-CI cotransport, and Na-K pump), in 11 normal inbred mouse strains. These strains are widely used, with abundantly available genetic and phenotypic information. We will set-up informative crosses to identify specific QTLs associated with meaningful differences in transport activities. Definition of the genes influencing erythrocyte hydration and ion transport in the mouse will enlighten explorations in the sickle mouse model, and will allow testing of candidate genes using knock in/out experiments. The ultimate intent is to validate in future studies the mouse candidate genes with appropriate association studies in patients. We anticipate that these studies will lead to identification of novel genes relevant to pathophysiology of sickle cell syndromes and other anemias, and of potential new therapeutic targets, markers of disease severity, and indicators of susceptibility to specific therapies.