Local Proliferation of Glia and their Interaction with Blood Vessels

描述(申请人提供)：我的长期目标是阐明神经胶质细胞发育的机制。这项应用的重点是表征大脑皮层星形胶质细胞的局部增殖，以及它们在出生后阶段与血管相互作用的机制。在出生后2周和3周，鼠脑内血管密度和胶质细胞数量均增加约4倍。目前还不清楚大量的星形胶质细胞来自哪里，以及它们如何与血管相互作用。我的初步数据显示，出生后星形胶质细胞的局部增殖广泛分布在大脑皮层的不同层面，这些星形胶质细胞在进入有丝分裂阶段时，与血管一起保留了它们的终足(星形胶质细胞的血管周围突起)。因此，我假设星形胶质细胞的局部增殖是皮质星形胶质细胞的主要来源，而皮质星形胶质细胞有助于出生后大脑中的终足形成。为了解决这一假设，我提出了两个具体的目标：(1)表征局部星形胶质细胞的增殖及其在大脑皮层中的命运和功能；(2)阐明局部产生的星形胶质细胞介导的血管周围端足形成的机制。我已经建立了两组转基因小鼠系，通过基因编码的荧光标记以前所未有的分辨率稀疏地标记星形胶质细胞，以及我开发的标记和记录分裂细胞的方法。因此，我独一无二地准备好进行这项新的研究。K99指导阶段(第1年和第2年)提出的研究重点是建立活体动物中神经胶质细胞增殖的逆转录病毒标记和成像方法，该方法将在莉莉·杨博士的监督下进行。R00独立阶段(第3年到第5年)将专注于表征通过局部增殖产生的星形胶质细胞的功能，以及它们与血管相互作用的机制。这项拟议的研究具有创新性，因为它将首次提供出生后大脑皮层星形胶质细胞局部增殖的直接证据，并展示它们如何整合到神经胶质网络中，并与血管形成终足结构。 公共卫生相关性：这些实验的结果将极大地提高我们对各种神经疾病的了解，例如由神经胶质-血管相互作用障碍或不受控制的神经胶质细胞增殖引起的缺血性中风和脑肿瘤。阐明神经胶质-血管相互作用的形成机制将有助于开发治疗这些神经系统疾病的新靶点。

DESCRIPTION (provided by applicant): My long-term goal is to elucidate mechanisms for glial development. The focus of this application is to characterize local proliferation of astrocytes in the cerebral cortex and the mechanism underlying their interaction with blood vessels at the postnatal stage. During postnatal weeks 2 and 3, the density of blood vessels and the number of glial cells both increase by ~4 fold in the rodent brain. It is still unclear where the large number of astrocytes come from and how they interact with blood vessels. My preliminary data show that postnatal local proliferation of astrocytes is widely distributed in different layers of the cerebral cortex, and these astrocytes retain their endfeet (perivascular processes of astrocytes) with blood vessels while they enter mitotic stages. I thus hypothesize that local prolifaration of astrocytes is a main source of cortical astrocytes that contribute to endfoot formation in the postnatal brain. To address the hypothesis, I propose two specific aims: (1) Characterize local proliferation of astrocytes and their fate and function in the cerebral cortex; (2) Elucidate the mechanism underlying endfoot formation around blood vessels mediated by locally generated astrocytes. I have established two groups of transgenic mouse lines to sparsely label astrocytes via genetically encoded fluorescent markers with unprecedented resolution, along with methods I developed to label and record dividing cells. I am therefore uniquely poised to undertake this novel study. Research proposed in the K99 Mentored phase (year 1 and 2) is concentrated on the establishment of methods for retroviral labeling and imaging of glial proliferation in live animals, which will be carried out with the supervision of Dr. Lily Jan. The R00 Independent phase (years 3 to 5) will focus on characterizing the function of astrocytes generated via local proliferation, and the mechanism underlying their interaction with blood vessels. The proposed research is innovative because it will provide the first direct evidence of postnatal local proliferation of astrocytes in cerebral cortex and show how they integrate into glial network and form endfoot structures with blood vessels. PUBLIC HEALTH RELEVANCE: The outcomes of these experiments will greatly improve our understanding of a variety of neurological diseases such as ischemic stroke and brain tumors caused by dysfunction of glial-vascular interaction or uncontrolled glial proliferation. Elucidation of the mechanism of formation of glial-vascular interaction will further facilitate development of new therapeutic targets for the treatment of these neurological diseases.