The Role of ABC Transporters in Stem Cells

描述（申请人逐字描述）：造血干细胞（HSC） 可以根据它们挤出荧光染料的能力来鉴定， 属性归因于属于跨膜蛋白的表达 ABC转运蛋白超家族。目前尚不清楚哪些转运蛋白表达 或者ABC转运蛋白是否在干细胞中起功能作用， 发展我们最近表明，一个ABC的强制表达 MDR 1基因产物P-糖蛋白（P-gp）是一种转运蛋白， 骨髓增生性疾病的扩增和发展 小鼠虽然这些数据清楚地表明，P-gp转运蛋白可以有 在干细胞中，P-gp的表达对于 正常的干细胞发育在靶向破坏MDR 1样 基因，正常的HSC存在，并表达另一个最近发现的ABC 名为Bcrpl的运输机。HSC中转运蛋白表达的保守性 表明正常干细胞可能需要转运蛋白功能， 发展为了验证这一假设，将Bcrp 1基因敲除， 鼠ES细胞，以及与mdr 1 a/B敲除小鼠的杂交将被分析， 造血系统的发育缺陷严格限制的表达 Bcrpl在干细胞群中的模式表明，它可能是一种新的 用于干细胞纯化的标记物。将进行分选实验， 确定Bcrpl（BCRP）表达是否将干细胞从 造血和肌肉组织。本提案的最后一个目标是确定 ABC转运蛋白表达失调与白血病的关系 在小鼠中使用可控的转基因表达系统，并通过直接 儿科白血病样本的研究。总之，预计这些 实验将提供有关ABC作用的新信息， 正常和白血病造血中的转运蛋白。

DESCRIPTION (Applicant's Description Verbatim): Hematopoietic stem cells (HSCs) can be identified on the basis of their ability to extrude fluorescent dyes, a property attributed to expression of transmembrane proteins belonging to the ABC transporter superfamily. It is not known which transporters are expressed on HSCs, or whether ABC transporters have a functional role in stem cell development. We have recently shown that enforced expression of one ABC transporter, the MDR 1 gene product P-glycoprotein (P-gp), resulted in HSC amplification and development of a myeloproliferative disorder in transplanted mice. While these data clearly show that the P-gp transporter can have functional effects in stem cells, expression of P-gp was not necessary for normal stem cell development. In mice with targeted disruptions of MDR 1-like genes, normal HSCs were present and expressed another recently identified ABC transporter named Bcrpl. This conservation of transporter expression in HSCs suggests that transporter function may be required for normal stem cell development. To test this hypothesis, the Bcrp1 gene will be knocked out in murine ES cells, and crosses with mdrl a/b knockout mice will be analyzed for developmental defects in hematopoiesis. The tightly restricted expression pattern of Bcrpl in stem cell populations suggests that it may be a novel marker for stem cell purification. Sorting experiments will be performed to determine whether Bcrpl (BCRP) expression identifies stem cells from hematopoietic and muscle tissue. The last aim of this proposal will define the relationship between deregulated expression of ABC transporters and leukemia by using controllable transgenic expression systems in mice, and through direct study of pediatric leukemia samples. Altogether, it is expected that these experiments will provide novel information regarding the role of ABC transporters in normal and leukemic hematopoiesis.