Polyadenylation induced translation in the brain

突触效能的长期变化可能调节树突状mRNA的调节翻译。虽然许多机制可能是负责这样的调节，一个似乎是参与细胞质聚腺苷酸化。这一过程发生在可能大多数后生动物的早期发育过程中，并控制卵母细胞成熟和身体平面形成所必需的几种母体mRNA的翻译。在相应mRNA的3'非翻译区中的两个顺式元件是多聚腺苷酸化所必需的，即富含U的胞质多聚腺苷酸化元件（CPE）和几乎普遍存在的六核苷酸AAUAAA。CPI被序列特异性RNA结合蛋白CPEB结合，CPEB是多聚腺苷酸化所必需的。除了卵母细胞外，CPEB还存在于大脑中，尤其是在海马、视觉皮质和小脑的浦肯野细胞中富集。更具体地说，CPEB存在于突触处，并与突触后密度共同纯化。CaMKII mRNA对长期记忆储存很重要，在其3'非翻译区含有CPE，并且这些CPE被CPEB结合。-CaMKII mRNA也经历经验依赖性的多聚腺苷酸化和翻译，表明其表达受CPEB控制。在这里，将探讨CPEB在大脑中的分子功能。将进行可能的CPEB参与mRNA定位到树突的分析。显性负CPEB突变蛋白将用于确定该分子在mRNA聚腺苷酸化和翻译中的重要性。酵母双杂交试验将用于鉴定脑中的CPEB相互作用蛋白。将构建富含响应于突触刺激而经历聚腺苷酸化的序列的cDNA文库。最后，将产生具有脑特异性CPEB基因缺失的小鼠系。这些实验将对学习和记忆的基础产生重要影响。

Long-term changes in synaptic efficacy may regulate the regulated translational of dendritic mRNAs. Although a number of mechanisms may be responsible for such regulation, one that appears to be involved is cytoplasmic polyadenylation. This process occurs during the early development of probably most metazoans, and controls the translation of several maternal mRNAs that are necessary for oocyte maturation and body plan formation. Two cis elements in the 3' untranslated region of responding mRNAs are necessary for polyadenylation, the U-rich cytoplasmic polyadenylation element (CPE) and the near-ubiquitous hexanucleotide AAUAAA. The CPI is bound by the sequence-specific RNA binding protein CPEB, which is essential for polyadenylation. In addition to oocytes, CPEB is found in the brain, and is particularly enriched in the hippocampus, visual cortex and Purkinje cells of the cerebellum. More specifically, CPEB is found at synapses, and co- purifies with the postsynaptic density. CaMKII mRNA, which is important for long term memory storage, contains CPEs within its 3' untranslated region, and these are bound by CPEB. -CaMKII mRNA also undergoes experience-dependent polyadenylation and translation, suggesting that its expression is controlled by CPEB. Here, the molecular function of CPEB in the brain will be explored. An analysis of possible CPEB involvement in mRNA localization to dendrites will be conducted. Dominant negative CPEB mutant proteins will be employed to determine the importance of this molecule in mRNA polyadenylation and translation. The yeast two-hybrid assay will be used to identify CPEB interacting proteins in the brain. A cDNA library enriched for sequences that undergo polyadenylation in response to synaptic stimulation will be constructed. Finally, a mouse line with a brain-specific deletion of the CPEB gene will be generated. These experiments will have important implications for the underling basis of learning and memory.