HoxA10 Function During Myeloid Differentiation

HoxA10 在骨髓分化过程中的功能

• 批准号: 6699680
• 负责人: Elizabeth Ann Eklund
• 金额: $ 26.46万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-02-06 至 2007-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6699680
• 关键词: Retroviridae; amidohydrolases; cell differentiation; clinical research; developmental genetics; gene induction /repression; hematopoiesis; human subject; immunogenetics; laboratory mouse; monocyte; myelogenous leukemia; myeloid stem cell; neoplasm /cancer genetics; phosphoproteins; phosphorylation; protein structure function; transcription factor; transfection /expression vector

DESCRIPTION (provided by applicant): The transcription factor HoxA10 is expressed early in myelopoiesis and is overexpressed in myeloid leukemia. These observations suggest that differentiation stage specific HoxA10 function may be involved in regulation of myelopoiesis. We noted that repressor elements in the promoters of the genes encoding the respiratory burst oxidase components gp91phox and p67phox (the CYBB and NCF2 genes) are similar to the derived DNA-binding consensus for HoxA10. We found that HoxA10 binds to these cis elements in EMSA with nuclear proteins from undifferentiated, but not WNy-differentiated, myeloid cells. Therefore, HoxA10 DNA-binding decreases as gp91phox and p67phox expression increases. Consistent with this, overexpression of HoxA10 represses gp91p0x and p67phox expression via these CYBB and NCF2 repressor elements. In vitro binding assays indicate that HoxA10 recruits transcriptional co-repressor proteins to the CYBB and NCF2 promoters. We found that IFNy-differentiation of myeloid cell lines results in HoxA10 tyrosine phosphorylation, which decreases HoxA10 DNA-binding affinity. Additionally, we found that SHP1 protein tyrosine phosphatase augments HoxA10 repression of the CYBB and NCF2 genes in undifferentiated myeloid cells. Therefore, we hypothesize that HoxA10 represses myeloid genes early in myelopoiesis and that HoxA10 DNA-binding is regulated by phosphorylation during differentiation. We will investigate this hypothesis by the following specific aims: Aim 1: Determine if HoxA10 repression requires recruitment of histone deacetylase activity to the CYBB and NCF2 genes. If so, does HoxA10 interact with co-repressor proteins directly, or via interaction with Pbxla? Aim 2: Determine if tyrosine phosphorylation during myeloid differentiation decreases the affinity of HoxA10 for the CYBB and NCF2 repressor elements. If so, does SHP1-PTP regulate HoxA10 phosphorylation.? Aim 3: Determine the roles of HoxA10 repression activity and tyrosine phosphorylation in leukemogenesis. These investigations will identify the molecular mechanisms of target gene regulation by HoxA10, which may suggest a role for HoxA10 in differentiation block in myeloid leukemia.

描述（由申请人提供）： 转录因子 HoxA10 是 在骨髓生成早期表达，并在粒细胞白血病中过度表达。这些 观察结果表明，分化阶段特定的 HoxA10 功能可能是 参与骨髓细胞生成的调节。我们注意到，抑制元件 编码呼吸爆发氧化酶成分的基因的启动子 gp91phox 和 p67phox（CYBB 和 NCF2 基因）与衍生的相似 HoxA10 的 DNA 结合共识。我们发现 HoxA10 与这些顺式结合 EMSA 中的元素带有未分化的核蛋白，但不是 WNy 分化的骨髓细胞。因此，HoxA10 DNA 结合随着时间的推移而减少 gp91phox 和 p67phox 表达增加。与此相一致的是，过度表达 HoxA10 通过 CYBB 和 NCF2 抑制 gp91p0x 和 p67phox 表达 阻遏元件。体外结合测定表明 HoxA10 招募 CYBB 和 NCF2 启动子的转录共阻遏蛋白。我们发现 骨髓细胞系的 IFNγ 分化产生 HoxA10 酪氨酸 磷酸化，降低 HoxA10 DNA 结合亲和力。此外，我们 发现 SHP1 蛋白酪氨酸磷酸酶增强了 HoxA10 对 未分化骨髓细胞中的 CYBB 和 NCF2 基因。因此，我们 假设 HoxA10 在骨髓细胞生成早期抑制骨髓基因，并且 HoxA10 DNA 结合在分化过程中受到磷酸化的调节。我们 将通过以下具体目标来研究该假设： 目标 1： 确定 HoxA10 抑制是否需要招募组蛋白脱乙酰酶 CYBB 和 NCF2 基因的活性。如果是这样，HoxA10 是否与 直接共抑制蛋白，还是通过与 Pbxla 相互作用？目标 2：确定 如果骨髓分化过程中酪氨酸磷酸化降低 HoxA10 对 CYBB 和 NCF2 阻遏元件的亲和力。如果是的话，是否 SHP1-PTP 调节 HoxA10 磷酸化。?目标 3：确定 HoxA10 的作用 白血病发生中的抑制活性和酪氨酸磷酸化。这些 研究将确定靶基因调控的分子机制 HoxA10，这可能表明 HoxA10 在分化阻断中的作用 粒细胞白血病。