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发育的机制。本应用的重点是描述出生后大脑皮层星形胶质细胞的局部增殖及其与血管相互作用的机制。出生后第2周和第3周，鼠脑血管密度和神经胶质细胞数量均增加约4倍。目前尚不清楚大量星形胶质细胞来自何处以及它们如何与血管相互作用。我的初步数据表明，出生后星形胶质细胞的局部增殖广泛分布于大脑皮层的不同层，这些星形胶质细胞在进入有丝分裂阶段时保留了它们的终足（星形胶质细胞的血管周围突）与血管。因此，我假设星形胶质细胞的局部增殖是大脑皮层星形胶质细胞的主要来源，有助于出生后大脑终足的形成。为了解决这一假设，我提出了两个具体目标：(1)表征星形胶质细胞的局部增殖及其在大脑皮层中的命运和功能；(2)阐明局部生成的星形胶质细胞介导血管周围终足形成的机制。我已经建立了两组转基因小鼠系，通过前所未有的分辨率的遗传编码荧光标记来稀疏标记星形胶质细胞，以及我开发的标记和记录分裂细胞的方法。因此，我以独特的姿态来进行这项新颖的研究。K99指导阶段（1、2年级）的研究重点是建立活体动物胶质细胞增殖的逆转录病毒标记和成像方法，这将在Dr. Lily .的指导下进行。R00独立阶段（3 ~ 5年级）将重点描述通过局部增殖产生的星形胶质细胞的功能及其与血管相互作用的机制。这项研究具有创新意义，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。

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.