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使移植方法的发展成为治疗癌症和血液病的可能。HSC的细胞周期状态决定了它们在条件受者体内的移植能力，并被认为是化疗耐药HSC来源的白血病的一种机制。HSC是高度静止的细胞，具有快速进入细胞周期并通过改变其极性和配置进行分化的能力 细胞内分子命运决定因素对微环境(ME)提示的响应。在骨髓(BM)造血中，干扰素I型(IFN-I)是一种病毒感染后产生的ME细胞因子，已被证明是诱导原本静止的造血干细胞(QHSC)增殖的关键正向调节因子。我们的初步数据表明，Scribble缺陷的HSC对干扰素-I不敏感，并在体内保持细胞静止。我们的初步数据还表明，在野生型HSC中，河马效应器YAP1也在ME信号的响应下调节干细胞的增殖，它是极化的，并与Scribble共存于细胞质中。Scribble缺失会导致YAP1转位为核常染色质，提示了一种新的Scribble介导的机制用于保护qHSC免受与细胞激活相关的潜在损伤。我们的数据表明，Scribble以一种上下文相关的方式明显地调节HSC细胞周期进程。我们认为ME干扰素-I诱导的HSC增殖信号程序依赖于Scribble，Scribble缺陷消除了HSC的极化，从而通过激活下游的河马效应器而减少了静止和随后的HSC耗竭。为了深入了解这些控制HSC活性的ME依赖的信号通路，我们计划分析Scribble熟练和缺陷HSC中的干扰素-I反应信号通路和河马信号。我们将利用流式细胞术和共聚焦显微镜来确定Scribble在调节这些信号中的作用。在功能上，我们将通过连续移植来检测野生型和Scribble结构-功能突变体在Scribble缺陷HSC中的重建能力。剖析控制HSC静止的微环境依赖的Scribble介导的分子机制将有助于提炼自然产生的干扰素分子的意义和治疗潜力，并确定干预HSC疾病的新靶点。

 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.