Ing4-deficiency enhances the regenerative capacity of multipotent progenitor cells

项目概要/摘要。长期造血干细胞（HSC）能够自我更新， 分化成所有成熟的造血谱系。这一过程的既定范例涉及 自我更新和HSC分化为祖细胞。我们提案的主要目标是 增强造血干细胞移植中干细胞和祖细胞自我更新的机制 患者接受HSC移植治疗非恶性疾病和病症的患者人数稳步上升， 发生在过去的二十年，但这些患者的生存率可以低至20-40%，在五年 移植后时期。这表明这些患者强烈需要改进的HSC移植。到 为了进一步了解HSC的功能和自我更新，我完成了第一个大规模的体内逆转录病毒（HCV） 以染色质因子为靶点的遗传筛选，染色质因子通过染色质的变化调节基因表达 结构从这个屏幕上，我们发现了植物同源异型（PHD）指和染色质的要求 相关蛋白Ing 4。作为Hbo 1染色质重塑复合物的一员，Ing 4与靶位点结合 通过识别H3 K4 me 3标记并增加组蛋白乙酰化的局部水平。Ing 4也 已显示负调节NF-κB、c-Myc、Hif 1a和p53。我们在Ing 4缺陷小鼠中的工作表明， Ing 4的缺失对骨髓中的造血有显著影响。这些小鼠表现出 HSC的水平和多能祖细胞（MPP）的损失。MPPs的移植表明， MPP越少，分化到MPP阶段的细胞就越能够进行稳健的、长期的 重组比野生型对应物，显示非常高的嵌合水平，长达9个月后， 移植我们假设Ing 4调节MPP细胞的自我更新特性，并且Ing 4的丢失 导致MPPs具有活化的干细胞样特性。根据本建议开展的工作将确定 在Ing 4缺陷型MPPs中改变的通路，以表征它们如何恢复功能的能力 比如HSC。如果成功，我们的研究将为重新激活自我更新途径提供新的机制。 这可能会为需要这种治疗的患者带来更成功的HSC移植。

Project summary/Abstract. Long-term hematopoietic stem cells (HSCs) are capable of self-renewal and differentiation into all mature hematopoietic lineages. The established paradigm for this process involves the self-renewal and differentiation of HSCs into progenitor cells. The primary goal of our proposal is to define mechanisms to enhance self-renewal in stem and progenitor cells for hematopoietic stem cell transplantation in patients. A steady rise in patients receiving HSC transplants for non-malignant diseases and disorders has occurred over the last two decades, but survival of these patients can be as low as 20-40% in the five year post-transplant period. This suggests a strong need for improved HSC transplants for these patients. To advance our understanding of HSC function and self-renewal, I completed the first large-scale in vivo reverse genetic screen targeting chromatin factors, which regulate gene expression through changes in chromatin structure. From this screen, we found a requirement for the plant homeodoming (PHD) finger and chromatin associated protein, Ing4. As a member of the Hbo1 chromatin remodeling complex, Ing4 binds to target loci through recognition of H3K4me3 marks and increases localized levels of histone acetylation. Ing4 has also been shown to negatively regulate NF-κB, c-Myc, Hif1a, and p53. Our work in Ing4-deficient mice has shown that loss of Ing4 has a dramatic effect on hematopoiesis in the bone marrow. These mice show increased levels of HSCs and a loss of multipotent progenitors (MPPs). Transplantation of MPPs shows that while there are fewer MPPs, the cells that do differentiate to the MPP stage are more capable of robust, long-term reconstitution than their wild-type counterparts, showing very high levels of chimerism up to 9 months post- transplant. We hypothesize that Ing4 regulates self-renewal properties in MPP cells and loss of Ing4 results in MPPs with activated stem cell-like properties. Work done under this proposal will identify the pathways altered in Ing4-deficient MPPs to characterize how they have regained the ability to function like HSCs. If successful, our studies will provide a new mechanism for re-activating self-renewal pathways. This could lead to more successful HSC transplants for patients needing this treatment.