Control of miRNA-mediated translational repression in neurons

描述(申请人提供)：突触可塑性与蛋白质树突状合成的调节有关，由此突触刺激激活存储在突触附近的预先存在的mRNAs的局部翻译。突触的局部蛋白质合成可以导致突触强度和有效性的长期调整。一个关键的悬而未决的问题是，本地化翻译控制是如何发生的。控制的两个特征是显而易见的：既有翻译的长期和结构性沉默，也有快速和诱导性的翻译沉默。这笔赠款旨在探索沉默/解除沉默背后的机制。我们的工作假设，这种控制的一部分是由microRNAs介导的。这类值得注意的非编码RNA抑制了mRNA转录本的翻译，转录本在其3‘非翻译区含有miRNA结合位点。众所周知，位于树突中的microRNAs能够抑制具有重要功能的mRNAs，并在一定条件下解除其表达。我们的目标是了解miRNAs如何锁定他们的目标mRNAs，以及突触活动如何释放他们的目标mRNAs进行翻译。为此，我们发现细胞在发生内吞作用时会释放靶标。内体将被抑制的复合体招募到它们的限制膜上，随着内体成熟到内体晚期，复合体被解离和翻转。这使得目标能够被释放。这项资助的目的是确定在非突触和突触神经元模型中，依赖活性的内吞作用是否从miRNA介导的抑制中释放mRNAs。如果我们发现这样一种机制，它将促进对突触可塑性的理解。对健康的意义是多方面的。了解调节突触可塑性的分子机制对于破译行为可塑性、精神疾病如何破坏行为可塑性以及指导新治疗技术的发展至关重要。 与公共卫生相关：microRNAs是基因表达的调节者，它们的功能障碍与各种形式的神经疾病有关。这个项目是为了了解microRNA如何控制神经元中的蛋白质翻译，特别是突触中的蛋白质翻译。它们与突触可塑性的关系尤其令人感兴趣。

DESCRIPTION (provided by applicant): Synaptic plasticity has been linked to the regulation of dendritic synthesis of proteins, whereby synaptic stimulation activates local translation of pre-existing mRNAs that are stored close to the synapse. Local protein synthesis at synapses can lead to long-lasting modification in synaptic strength and efficacy. A key unanswered question is how localized translation control occurs. Two features of control are apparent; there is long-term and constitutive silencing of translation but there is also rapid and inducible de-silencing of translation. This grant seeks to explore the mechanisms behind silencing/de-silencing. We are working with the assumption that some of this control is mediated by microRNAs. This remarkable class of non-coding RNAs repress the translation of mRNA transcripts, which contain miRNA-binding sites in their 3' untranslated regions. MicroRNAs located in dendrites are known to repress functionally important mRNAs, and derepress under certain conditions. Our goal is to understand how miRNAs lock up their target mRNAs, and how synaptic activities release their target mRNAs for translation. To this end, we have discovered that cells release targets when endocytosis occurs. Endosomes recruit repressed complexes to their limiting membranes, and as endosomes mature to late endosome stages, complexes are dissociated and turned over. This enables targets to be released. The aims of the grant are to determine if activity-dependent endocytosis releases mRNAs from miRNA-mediated repression in a non-synaptic and synaptic neuronal model. If we uncover such a mechanism, it would advance understanding of synaptic plasticity. The significance to health is manifold. Understanding the molecular mechanisms that regulate synaptic plasticity is of paramount importance to decipher behavioral plasticity, how mental illness can disrupt it, and guide development of new therapeutic technologies. PUBLIC HEALTH RELEVANCE: MicroRNAs are regulators of gene expression, and their dysfunction is linked to diverse forms of neurological disorders. This project is to understand how microRNAs control protein translation in neurons, particularly in synapses. Their relationship to synaptic plasticity is of particular interest.