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， 特性归因于属于 ABC运输机超级家族。目前还不知道表达了哪些转运蛋白 或ABC转运蛋白在干细胞中是否具有功能作用 发展。我们最近证明了一个ABC的强制表达 MDR-1基因产物P-糖蛋白(P-gp)转运蛋白导致HSC 移植后一种骨髓增生性疾病的扩增和发展 老鼠。虽然这些数据清楚地表明P-gp转运体可以 干细胞的功能效应，P-gp的表达不是必需的 干细胞发育正常。在靶向干扰mdr1样蛋白的小鼠中 基因，正常的肝星状细胞存在，并表达另一种最近发现的ABC 一个叫Bcrpl的传送者。肝星状细胞转运蛋白表达的保守性 提示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，Bcrp1基因将在 小鼠ES细胞，并与mdrl a/b基因敲除小鼠杂交，将分析 造血方面的发育缺陷。严格限制的表达 Bcrpl在干细胞群体中的分布模式表明它可能是一种新的 干细胞纯化的标志物。将进行分选实验以 确定Bcrp1(BCRP)表达是否识别干细胞来自 造血和肌肉组织。该提案的最后一个目标将定义 ABC转运蛋白失控表达与白血病的关系 在小鼠中使用可控的转基因表达系统，并通过直接 儿童白血病样本的研究。总而言之，预计这些 实验将提供有关ABC角色的新信息 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.