RETINOIC ACID RECEPTORS AND MYELOPOIESIS

维甲酸（RA）的多种生物学作用被认为是 通过特异性RA受体（RAR）介导。 RA诱导 急性白血病患者白血病细胞的粒系分化 早幼粒细胞白血病（APL）。 大多数RA敏感的APL样本都含有 特异性15：17染色体易位，涉及RAR-α 基因座，并导致异常的RAR-α融合转录物（命名为 PML-RAR-α）。 产生的病理生理后果， 这种异常的PML-RAR-α融合转录本及其与 白血病发生目前尚不清楚。 也不知道是什么角色，如果 RA可能参与正常造血的调节。 这项建议 计划利用逆转录病毒介导的基因 转导以将异常RA受体构建体转移到 造血细胞系和正常造血干细胞。 的 需要解决的具体问题包括： 具体目的I）异常PML-RAR-α的表达如何影响PML-RAR-α的表达， 融合基因是否与APL的发病有关？ 为了探讨产生的病理生理后果， PML-RAR-α融合基因，我们将利用逆转录病毒介导的基因 转导以在RA敏感性和RA-敏感性两者中表达该融合基因。 耐药造血细胞系，并比较 未感染的细胞与逆转录病毒感染的细胞对RA的反应。 我们还将 用含有逆转录病毒载体感染小鼠造血干细胞 PML-RAR-α融合基因，以研究这种 体内异常RA受体。 特定目的II）RA和RA受体（RAR-α）在 调节正常的造血功能 几条间接证据表明RA和RA受体 （RAR-α）可能参与调节正常造血。 到 直接处理这个问题，我们将确定对 引入突变体“显性阴性”的造血分化 将RAR-α导入造血细胞系， 正常造血以及正常小鼠造血干细胞 体内细胞 虽然我们提出的研究仅限于造血细胞， 可能最终提供洞察作用正常或异常RA 受体可能在其他人类恶性肿瘤的发展中起作用。

The diverse biologic effects of retinoic acid (RA) are thought to be mediated through specific RA receptors (RARs). RA induces the granulocytic differentiation of leukemia cells in patients with acute promyelocytic leukemia (APL). Most RA-sensitive APL samples harbor a specific 15:17 chromosome translocation, which involves the RAR-alpha locus and leads to an aberrant RAR-alpha fusion transcript (designated PML-RAR-alpha). The pathophysiologic consequences of the generation of this aberrant PML-RAR-alpha fusion transcript and its relationship to leukemogenesis are presently unclear. It is also unknown what role, if any, RA might play in regulating normal hematopoiesis. This proposal plans to approach these questions by utilizing retroviral-mediated gene transduction to transfer aberrant RA receptor constructs into hematopoietic cell lines and normal hematopoietic stem cells. The specific questions to be addressed include the following: Specific Aim I) How does the expression of the aberrant PML-RAR-alpha fusion gene relate to the pathogenesis of APL? To explore the pathophysiologic consequences of the generation of the PML-RAR-alpha fusion gene, we will utilize retrovirus-mediated gene transduction to express this fusion gene in both RA-sensitive and RA- resistant hemopoietic cell lines and compare the differentiation of the uninfected vs. retrovirus-infected cells in response to RA. We will also infect murine hemopoietic stem cells with a retroviral vector harboring the PML-RAR-alpha fusion gene to study the leukemogenic potential of this aberrant RA receptor in vivo. Specific Aim II) What roles do RA and RA receptors (RAR-alpha) play in regulating normal hematopoiesis? Several lines of indirect evidence suggest that RA and the RA receptor (RAR-alpha) may be involved in regulating normal hematopoiesis. To directly approach this question we will determine the effect on hematopoietic differentiation of introducing a mutant "dominant negative" RAR-alpha into a hematopoietic cell line that mimics several aspects of normal hematopoiesis as well as into normal murine hematopoietic stem cells in vivo. Although our proposed studies are confined to hematopoietic cells, they may eventually provide insight into the role normal or abnormal RA receptors might play in the development of other human malignancies.