Sackler Faculty of Medicine, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel.
Edmond J. Safra Center for Bioinformatics, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel.
Cells. 2023 Jan 6;12(2):233. doi: 10.3390/cells12020233.
Rapid responses to changes within subcellular compartments of highly polarized cells, such as neuron axons, depend on local translation and post-transcriptional regulation. The mechanism by which microRNAs (miRNAs) regulate this process is not fully understood. Here, using live cell imaging and RNA sequencing analysis, we demonstrated how miRNAs can differentially control hundreds of transcripts at the subcellular level. We demonstrated that the seed match length of the miRNA target-sequence regulates both mRNA stability and protein translation rates. While longer seed matches have an increased inhibitory effect, transcriptome analysis did not reveal differences in seed match length between axonal and somata mRNAs of motor neurons. However, mRNA variants with longer 3'UTR are enriched in axons and contain multiple repeats of specific miRNA target sequences. Finally, we demonstrated that the long 3'UTR mRNA variant of the motor protein Kif5b is enriched explicitly in motor neuron axons and contains multiple sequence repeats for binding miR-129-5p. This subsequently results in the differential post-transcriptional regulation of kif5b and its synthesis in axons. Thus, we suggest that the number of miRNA binding sites at the 3'UTR of the mRNA, rather than the miRNA seed match length, regulates the axonal transcriptome.
快速响应高度极化细胞（如神经元轴突）亚细胞区室的变化依赖于局部翻译和转录后调控。miRNAs（microRNAs）调节这一过程的机制尚不完全清楚。在这里，我们使用活细胞成像和 RNA 测序分析，展示了 miRNAs 如何在亚细胞水平上差异调控数百个转录本。我们证明了 miRNA 靶序列的种子匹配长度调节 mRNA 稳定性和蛋白质翻译率。虽然较长的种子匹配具有增强的抑制作用，但转录组分析并未揭示轴突和运动神经元胞体 mRNA 之间种子匹配长度的差异。然而，具有较长 3'UTR 的 mRNA 变体在轴突中富集，并包含多个特定 miRNA 靶序列的重复。最后，我们证明了运动蛋白 Kif5b 的长 3'UTR mRNA 变体在运动神经元轴突中特异性富集，并包含多个用于结合 miR-129-5p 的 miRNA 靶序列重复。这随后导致 kif5b 的差异转录后调控及其在轴突中的合成。因此，我们认为 mRNA 3'UTR 上的 miRNA 结合位点数量，而不是 miRNA 种子匹配长度，调节了轴突转录组。
