Role of PHF6 in Normal Hematopoiesis and hematopoietic stem cell biology

PHF6 在正常造血和造血干细胞生物学中的作用

• 批准号: 10063768
• 负责人: Feng-Chun Yang
• 金额: $ 30.7万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-15 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10063768
• 关键词: Role; PHF6; Normal; Hematopoiesis; hematopoietic

The plant homeodomain finger 6 (PHF6) is a member of the plant homeodomain (PHD)-like finger family genes. PHF6 is frequently mutated in T-cell acute lymphoblastic leukemia (T-ALL, ~15%) and various myeloid malignancies including acute myeloid leukemia (AML, ~3%), myelodysplastic syndrome (MDS, ~3%) and chronic myelomonocytic leukemia (CMML, ~5%). Interestingly, the PHF6 genetic lesions in hematological malignancies are largely frameshift and nonsense mutations distributed throughout the gene, indicating that these PHF6 mutations likely result in the loss of WT PHF6 and the expression of a truncated PHF6. Furthermore, clinical studies showed that PHF6 mutations confer worse overall survival in patients with MDS and AML. Despite the clinical significance of PHF6 mutations in hematologic neoplasms, the role of PHF6 in normal hematopoiesis and the impact of its mutations on the hematopoietic stem/progenitor cell (HSPC) functions remain unknown. In addition, it is not known whether the truncated-PHF6 leads to a bona fide loss-of- function or exerts a gain-of-function in hematopoiesis. Given the fact that PHF6 is located on the X chromosome and its mutations are male dominant, we hypothesize that the PHF6 mutations confer a gain-of- function in vivo. We therefore generated a conditional Phf6 knock-out (Phf6flox) mouse model to determine the role of PHF6 in normal hematopoiesis and whether loss of Phf6 affect HSPC cell fate and functions. In addition, we also established two transgenic mice expressing two different patient-derived truncated PHF6 (Phf6R274X and Phf6R342XTg) solely in hematopoiesis to determine the impact of truncated PHF6 on HSPC activities. Our preliminary data showed that Phf6-loss in mice increase hematopoietic stem cell self-renewal, indicating that PHF6 plays an important role in HSC regulation. We also found that PHF6 truncation expression confer a gain-of-function to promote HSC self-renewal. With these models in hand, we will determine the hematological phenotypes of mice with combined Phf6-inactivation and expression of truncated PHF6 in hematopoiesis, and define the cellular and molecular mechanisms by which PHF6 and its truncated mutations impact on HSPC functions. Mechanistically, we will identify key PHF6 and truncated PHF6 binding partners and determine the importance of these interactions to their genomic localization and common target gene expression in HSPCs. These studies will greatly improve our understanding for the role of PHF6 in normal hematopoiesis as well as the impact of PHF6 mutations on HSPC functions. Moreover, these PHF6 mutant models offer a biological platform in which drugs can be tested and developed. These studies are timely and fundamentally important for advancing our knowledge on PHF6 in normal hematopoiesis and HSPC biology.

植物同源域6（PHF6）是植物同源域（PHD）类似手指家族基因的成员。 PHF6在T细胞急性淋巴细胞白血病（T-All，〜15％）和各种髓样中经常突变 恶性肿瘤包括急性髓性白血病（AML，〜3％），骨髓增生综合征（MDS，〜3％）和 慢性脊髓细胞性白血病（CMML，〜5％）。有趣的是，血液学中的PHF6遗传病变 恶性肿瘤在很大程度上是在整个基因中分布的框架和胡说八道的突变，表明 这些PHF6突变可能导致WT PHF6的丧失和截短的PHF6的表达。 此外，临床研究表明，PHF6突变赋予MDS患者的总体存活率较差 和AML。尽管PHF6突变在血液学肿瘤中具有临床意义，但PHF6在 正常造血及其突变对造血茎/祖细胞（HSPC）的影响 功能仍然未知。此外，尚不知道截短的phf6是否导致真正的损失 功能或在造血中发挥功能收益。鉴于PHF6位于X上的事实 染色体及其突变是雄性的，我们假设PHF6突变赋予了一种 在体内功能。因此，我们生成了有条件的PHF6敲除（PHF6FLOX）小鼠模型来确定 PHF6在正常造血中的作用以及PHF6的丧失是否影响HSPC细胞的命运和功能。在 此外，我们还建立了两只表达两只不同患者衍生的截短PHF6的转基因小鼠 （PHF6R274X和PHF6R342XTG）仅在造血中确定截短的PHF6对HSPC的影响 活动。我们的初步数据表明，小鼠中的PHF6损伤会增加造血干细胞自我更新， 表明PHF6在HSC调节中起重要作用。我们还发现PHF6截断表达式 授予功能奖励以促进HSC自我更新。借助这些模型，我们将确定 小鼠的血液学表型与PHF6灭活结合和截短的PHF6表达 造血，并定义PHF6及其截断突变的细胞和分子机制 对HSPC功能的影响。从机械上讲，我们将识别密钥PHF6和截短的PHF6绑定伙伴 并确定这些相互作用对它们的基因组定位和共同靶基因的重要性 在HSPC中的表达。这些研究将大大提高我们对PHF6在正常中的作用的理解 造血以及PHF6突变对HSPC功能的影响。而且，这些PHF6突变体 模型提供了一个生物平台，可以在其中测试和开发药物。这些研究是及时的， 对于在正常造血和HSPC生物学中促进我们对PHF6的知识的根本重要。