Role of PHF6 in Normal Hematopoiesis and hematopoietic stem cell biology

植物同源结构域Finger 6(PHF6)是植物同源结构域(PhD)类Finger家族基因的一员。 PHF6在T细胞急性淋巴细胞白血病(T-ALL，~15%)和各种髓系中频繁突变 恶性肿瘤包括急性髓系白血病(AML，~3%)、骨髓增生异常综合征(MDS，~3%)和 慢性粒-单核细胞白血病(CMML)，占5%。有趣的是，血液学中的PHF6基因损害 恶性肿瘤在很大程度上是移码和无义突变，分布在整个基因中，表明 这些PHF6突变可能导致WT PHF6的丢失和截短的PHF6的表达。 此外，临床研究表明，PHF6突变使MDS患者的总体存活率更低。 和急性髓系白血病。尽管PHF6突变在血液肿瘤中具有临床意义，但PHF6在血液肿瘤中的作用 正常造血及其突变对造血干/祖细胞的影响 其功能仍不得而知。此外，目前尚不清楚截断的PHF6是否会导致真正的- 在造血方面发挥作用或发挥作用。鉴于PHF6位于X 染色体及其突变是男性显性的，我们假设PHF6突变带来了- 在体内发挥作用。因此，我们生成了一个有条件的Phf6基因敲除(Phf6flx)小鼠模型来确定 PHF6在正常造血中的作用以及PhF6的缺失是否影响HSPC细胞的命运和功能。在……里面 此外，我们还建立了两个转基因小鼠，表达两个不同的患者来源的截短PHF6 (Phf6R274X和Phf6R342XTg)单独在造血中检测截短型PHF6对HSPC的影响 活动。我们的初步数据显示，小鼠体内Phf6的缺失增加了造血干细胞的自我更新， 提示PHF6在HSC的调节中起重要作用。我们还发现PHF6截断表达式 授予功能收益以促进HSC自我更新。有了这些模型，我们将确定 联合应用Phf6灭活小鼠的血液学表型及截短型PHF6在小鼠体内的表达 造血，并确定PHF6及其截断突变的细胞和分子机制 对HSPC功能的影响。从机制上讲，我们将确定关键的PHF6和截断的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。这些研究将极大地提高我们对PHF6在正常组织中的作用的理解。 造血以及PHF6突变对HSPC功能的影响。此外，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，而且 对于提高我们对PHF6在正常造血和HSPC生物学中的认识具有重要意义。

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.