Investigating the Effects of Stem Cell Positional Identity on Brain Tumor Development

项目总结 广泛的、长期的目标是了解干细胞群体中的异质性如何影响 疾病状态和脑部肿瘤的发展。提议的项目的目标是调查如何 大脑不同区域的干细胞/祖细胞对脑的形成有不同的贡献。 结节性硬化症(TSC)的肿瘤。TSC是一种mTOR途径过度活跃的疾病， 导致细胞大小、存活和增殖增加。TSC患者可能发展为两种肿瘤类型中的任何一种 在脑室下区(SVZ)内，成人和儿童脑中最大的干细胞生态位。 它们可以发展成称为室管膜下结节(SENS)的良性无症状小肿瘤，也可以发展成较大的肿瘤。 可能危及生命的肿瘤，称为室管膜下巨细胞星形细胞瘤(SEGAS)。在临床上，这些 肿瘤类型按大小和位置区分，SEGA较大且局限于腹侧SVZ。 尽管有明显的预后差异，但驱动特定部位、更大肿瘤发展的机制是 不是很清楚。最近的研究确定，SVZ内的干细胞和祖细胞具有 位置认同--它们在生态位中的位置可以预测它们所产生的后代的类型。此属性 似乎是内在的，因为细胞在移植后保持其潜力。这一新信息提供了一个 耐人寻味的可能性是，被认为由SVZ干细胞/祖细胞形成的SEGA可能反映了 其原产地的属性。此外，干细胞/祖细胞的位置可能决定其 对TSC1/2突变的易感性。最重要的假设是细胞固有的、区域特异性的 干细胞/祖细胞信号的差异促进了脑部特定部位肿瘤的形成。 本项目的具体目标是：(1)确定细胞位置对神经肿瘤的内在影响 结节性硬化症的发展和(2)剖析mTOR信号通路组件 背侧和腹侧神经干/祖细胞不同。为了实现这些目标，我们将使用 条件性小鼠TSC模型结合局部Cre活性检测特异性 干细胞/祖细胞亚群导致更大的肿瘤形成。为了配合这个模型，我们将使用主茎 用显微镜和一种新的流式细胞术检测野生型和突变型细胞中的mTOR信号 基于细胞学的方法。为了实现拟议的工作，我们正在将临床经验与我们的 合作者Kevin Ess博士，与磷酸特定的流式细胞术世界专家合作(Jonathan博士 爱尔兰)，并利用我们实验室针对干细胞利基内的亚群的独特技术。这个 拟议的研究具有很高的相关性，因为它将揭示关于TSC脑起源的新信息 肿瘤。此外，这项工作广泛适用于许多领域，因为它研究了干细胞如何 具有不同的基础代谢程序，并有可能通过依赖于生长的途径发出信号 它们在干细胞中的位置。

PROJECT SUMMARY The broad, long-term objectives are to understand how heterogeneity within stem cell populations affects disease states and tumor development in the brain. The goal of the proposed project is to investigate how stem/progenitor cells within different regions of the brain can differentially contribute to the formation of brain tumors in Tuberous Sclerosis Complex (TSC). TSC is a disease of hyperactive mTOR pathway activity, resulting in increased cell size, survival and proliferation. TSC patients may develop either of two tumor types within the within the subventricular zone (SVZ), the largest stem cell niche in the adult and pediatric brain. They can develop small benign asymptomatic tumors, called subependymal nodules (SENS) or develop larger potentially life-threatening tumors, termed subependymal giant cell astrocytomas (SEGAs). Clinically, these tumor types are distinguished by size and location, with SEGAs being larger and restricted to the ventral SVZ. Despite clear prognostic differences, the mechanisms driving location-specific, larger tumor development are not well understood. Recent work has determined that the stem and progenitor cells within the SVZ have a positional identity- their location within the niche can predict the type of progeny they create. This property appears to be intrinsic as the cells retain their potential upon transplantation. This new information presents an intriguing possibility that SEGAS, which are thought to form from SVZ stem/progenitor cells, may reflect the properties of their location of origin. Additionally, the location of a stem/progenitor cell may determine its susceptibility to mutations in TSC1/2. The overarching hypothesis is that cell-intrinsic, region-specific differences in stem/progenitor-cell signaling promote the formation of location-specific tumors in the brain. The specific aims of this project are to (1) determine the intrinsic effects of cell location on neural tumor development in Tuberous Sclerosis Complex and (2) dissect the mTOR signaling pathway components that differ between dorsal and ventral neural stem/progenitor cells. To accomplish these aims, we will use a conditional mouse model of TSC in combination with localized Cre activity to test the combination of specific stem/progenitor cell subgroups to larger tumor formation. In tandem with this model, we will use primary stem cell cultures to examine mTOR signaling in wild type and mutant cells using both microscopy and a novel flow- cytometry based approach. To achieve the proposed work, we are incorporating a clinical experience with our collaborator Dr. Kevin Ess, collaboration with a world expert in phospho-specific flow cytometry (Dr. Jonathan Irish) and utilizing our lab’s unique technique of targeting subpopulations within the stem cell niche. The proposed research is highly relevant as it will reveal novel information regarding the origin of TSC brain tumors. Additionally, this work is broadly applicable to many fields as it investigates how stem cells can possess differential basal metabolic programming and potential to signal through growth pathways depending on their location within a stem cell niche.