Scribble in hematopoietic stem cell activity

 描述（由申请人提供）：造血干细胞（HSC）重建造血系统的潜力已经允许开发治疗癌症和血液病的移植方法。HSC的细胞周期状态定义了它们在条件接受者中移植的能力，并被假设为化疗耐药HSC衍生的白血病的机制。HSC是高度静止的细胞，具有快速进入细胞周期的能力，并通过其极性和配置的变化分化 细胞内的分子命运决定因素在响应微环境（ME）线索。在骨髓（BM）造血中，I型干扰素（IFN-I），一种响应于病毒感染而产生的ME细胞因子，已被证明是诱导原本静止的造血干细胞（qHSC）增殖的关键正调节剂。我们的初步数据表明，Scribble缺陷型HSC对IFN-1不敏感，并在体内保持细胞静止。我们的初步数据还表明，河马效应Yap 1，它也调节干细胞增殖响应ME信号，极化和共定位在细胞质中与野生型HSC的Scribble。HSC中Scribble的缺乏导致Yap 1易位至核常染色质，这表明Scribble介导的一种新型机制可用于保护qHSC免受与细胞激活相关的潜在损伤。我们的数据表明，Scribble明显调节HSC细胞周期的进展，在上下文依赖性的方式。我们认为ME IFN-1诱导的HSC增殖信号传导程序依赖于Scribble，并且Scribble缺陷消除HSC极化，导致静止减少，随后通过激活下游Hippo效应子导致HSC耗竭。为了深入了解这些控制HSC活性的ME依赖性信号通路，我们计划分析Scribble熟练和缺乏HSC中的IFN-I应答信号通路和Hippo信号通路。我们将利用流式细胞术和共聚焦显微镜来定义Scribble在介导这些信号中的作用。在功能上，我们将通过系列移植测试野生型和Scribble结构-功能突变体在Scribble缺陷HSC中的重建能力。剖析微环境依赖的Scribble介导的分子机制，管理HSC静止将有助于完善的意义和治疗潜力的天然存在的IFN分子，并确定新的目标，干预HSC疾病。

 DESCRIPTION (provided by applicant): The potential of hematopoietic stem cells (HSC) to reconstitute the hematopoietic system has allowed for the development of transplantation approaches to treat cancer and hematologic diseases. Cell cycle status of HSC defines their ability to engraft in conditioned recipients and has been hypothesized as a mechanism for chemotherapy-resistant HSC-derived leukemias. HSC are highly quiescent cells with the ability to rapidly enter the cell cycle and differentiate through changes in their polarity and disposition of intracellular molecular fate determinants in response to microenvironment (ME) cues. In bone marrow (BM) hematopoiesis, interferons type I (IFN-I), a ME cytokine produced in response to viral infection, have been shown to be a crucial positive regulator to induce proliferation of otherwise quiescent hematopoietic stem cells (qHSC). Our preliminary data indicate that Scribble deficient HSC are insensitive to IFN-I and retain cellular quiescence in vivo. Our preliminary data also show that the Hippo effector Yap1, which also regulates stem cell proliferation in response to ME signals, is polarized and co-localizes in the cytoplasm with Scribble in wild type HSC. Deficiency of Scribble in HSC results in Yap1 translocation to nuclear euchromatin suggesting a novel Scribble-mediated mechanism used to protect qHSC from potential damage associated with cellular activation. Our data suggests that Scribble distinctly regulates HSC cell cycle progression in a context-dependent manner. We believe that ME IFN-I induced HSC proliferative signaling program depends on Scribble and that Scribble deficiency abrogates HSC polarization leading to reduced quiescence and subsequent HSC exhaustion through activation of downstream Hippo effectors. To gain insight into these ME dependent signaling pathways that control HSC activity, we plan to analyze both IFN-I response signaling pathways and Hippo signaling in Scribble proficient and deficient HSC. We will utilize flow cytometry and confocal microscopy to define a role for Scribble in mediating such signals. Functionally, we will test the reconstitution abilities of wild type and Scribble structure-functio mutants in Scribble deficient HSC through serial transplantations. Dissecting the microenvironment dependent Scribble-mediated molecular mechanisms that govern HSC quiescence will help refine the significance and therapeutic potential of naturally occurring IFN molecules and identify novel targets for intervention in HSC disease.