LOCAL TRANSLATION IN ASTROCYTES

突触的失调被认为是一系列神经系统疾病的基础，星形胶质细胞是 突触维持、形成和消除的关键介质。神经元形成更多的突触时，共同- 与星形胶质细胞一起培养，并且单个星形胶质细胞可以在体内包裹100，000个突触。这一关键作用导致 “三重突触”模型：突触不仅由突触前终末和突触后终末组成， 密度，但也包括外周星形胶质细胞的过程（PAP）。像树突和终扣一样，PAP也有一个 特定的蛋白质组成，并在响应局部活性时进行形态学重塑。 大量的研究表明，突触重塑是由神经元中的局部翻译调节的， 特别是在枝晶中。特定的mRNAs穿梭进入树突，在那里它们的翻译可以被刺激 通过各种细胞外信号，允许微调调节局部蛋白质合成。新 合成的蛋白质被认为是介导加强个体突触的基础， 记忆，因为抑制翻译也会抑制记忆的形成。由于PAP和树突都被重塑 在对活动的反应中，很可能这两种反应对于提高个体的总体功效都是必不可少的。 突触对经验的反应。因此，该领域的一个关键问题是，星形胶质细胞是否也能像神经元一样， 将特定的mRNA定位到它们的翻译过程中？在这里，我们将使用生物化学来解决这个问题。 测试PAP中特异性mRNA的富集和翻译的方法和功能测定。我们 将寻求：1）确定定位于星形胶质细胞核糖体的转录过程，2）确定是否 转录物本身的序列特征介导它们在星形胶质细胞中的局部翻译，3）决定 神经元活动的分子线索是否能够刺激星形胶质细胞的局部翻译。

Dysregulation of synapses is thought to underlie a range of neurological disorders, and astrocytes are key mediators of synaptic maintenance, formation and elimination. Neurons form more synapses when co- cultured with astrocytes, and a single astrocyte may ensheath 100,000 synapses in vivo. This critical role led to the “tripartite synapse” model: the synapse is not only comprised of the presynaptic bouton and postsynaptic density but also includes a peripheral astroglial process(PAP). Like dendrites and boutons, the PAP has a specific protein composition and is remodeled morphologically in response to local activity. Extensive work has demonstrated that synaptic remodeling is regulated by local translation in neurons, particularly in the dendrite. Specific mRNAs are shuttled into dendrites where their translation can be stimulated by a variety of extracellular signals, allowing for fine-tuned regulation of local protein synthesis. Newly synthesized proteins are thought to mediate the strengthening of individual synapses that underlies learning and memory, as inhibiting translation also inhibits formation of memory. As both PAPs and dendrites are remodeled in response to activity, it is likely that both responses are essential to increasing the overall efficacy of individual synapses in response to experience. Thus a key question in the field is are astrocytes, like neurons, also able to localize specific mRNAs to their processes for translation? Here, we will address this question using biochemical approaches and functional assays to test for the enrichment and translation of specific mRNAs in the PAP. We will seek to: 1) identify the transcripts localized to astroglial ribosomes in processes, 2) determine whether features in the sequence of the transcripts themselves mediate their local translation in astrocytes, 3) determine whether molecular cues of neuronal activity are capable of stimulating local translation in astrocytes.