Fukuchi Mamoru, Shibasaki Yumi, Akazawa Yuto, Suzuki-Masuyama Hitoshi, Takeuchi Ken-Ichi, Iwazaki Yumika, Tabuchi Akiko, Tsuda Masaaki
Laboratory of Molecular Neuroscience, Faculty of Pharmacy, Takasaki University of Health and Welfare, 60 Nakaorui-machi, Takasaki, Gunma, 370-0033, Japan; Laboratory of Molecular Neurobiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan.
Laboratory of Molecular Neuroscience, Faculty of Pharmacy, Takasaki University of Health and Welfare, 60 Nakaorui-machi, Takasaki, Gunma, 370-0033, Japan.
Neurochem Int. 2024 Dec;181:105889. doi: 10.1016/j.neuint.2024.105889. Epub 2024 Oct 23.
Brain-derived neurotrophic factor (BDNF) is essential for numerous neuronal functions, including learning and memory. The expression of BDNF is regulated by distinctive transcriptional and post-transcriptional mechanisms. The Bdnf gene in mice and rats comprises eight untranslated exons (exons I-VIII) and one exon (exon IX) that contains the pre-proBDNF coding sequence. Multiple splice donor sites on the untranslated exons and a single acceptor site upstream of the coding sequence result in the characteristic exon skipping patterns that generate multiple Bdnf mRNA variants, which are essential for the spatiotemporal regulation of BDNF expression, mRNA localization, mRNA stability, and translational control. However, the regulation of Bdnf pre-mRNA splicing remains unclear. Here, we focused on the splicing of Bdnf exon I-IX pre-mRNA. We first constructed a minigene to evaluate Bdnf exon I-IX pre-mRNA splicing. Compared with Bdnf exon I-IX pre-mRNA splicing in non-neuronal NIH3T3 cells, splicing was preferentially observed in primary cultures of cortical neurons. Additionally, a series of overexpression and knockdown experiments suggested that neuro-oncological ventral antigen (NOVA) 2 is involved in the neuron-selective splicing of Bdnf exon I-IX pre-mRNA. Supporting this finding, endogenous Nova2 mRNA expression was markedly higher in neurons, and a strong correlation between endogenous Bdnf exon I-IX and Nova2 mRNA was observed across several brain regions. Furthermore, Bdnf exon I-IX pre-mRNA splicing was facilitated by Ca signals evoked via L-type voltage-dependent Ca channels. Notably, among the Bdnf pre-mRNA splicing investigated in the current study, neuron-selective and activity-dependent splicing was observed in Bdnf exon I-IX pre-mRNA. In conclusion, Bdnf exon I-IX pre-mRNA splicing is preferentially observed in neurons and is facilitated in an activity-dependent manner. The neuron-selective and activity-dependent splicing of Bdnf exon I-IX pre-mRNA may contribute to the efficient induction of Bdnf exon I-IX expression in neurons.
脑源性神经营养因子（BDNF）对包括学习和记忆在内的众多神经元功能至关重要。BDNF的表达受独特的转录和转录后机制调控。小鼠和大鼠的Bdnf基因包含八个非翻译外显子（外显子I - VIII）和一个包含前原BDNF编码序列的外显子（外显子IX）。非翻译外显子上的多个剪接供体位点以及编码序列上游的单个受体位点导致了特征性的外显子跳跃模式，产生多种Bdnf mRNA变体，这些变体对于BDNF表达、mRNA定位、mRNA稳定性和翻译控制的时空调节至关重要。然而，Bdnf前体mRNA剪接的调控仍不清楚。在此，我们聚焦于Bdnf外显子I - IX前体mRNA的剪接。我们首先构建了一个微型基因来评估Bdnf外显子I - IX前体mRNA的剪接。与非神经元NIH3T3细胞中的Bdnf外显子I - IX前体mRNA剪接相比，剪接在皮质神经元原代培养物中更易观察到。此外，一系列过表达和敲低实验表明，神经肿瘤腹侧抗原（NOVA）2参与了Bdnf外显子I - IX前体mRNA的神经元选择性剪接。支持这一发现的是，内源性Nova2 mRNA表达在神经元中明显更高，并且在多个脑区观察到内源性Bdnf外显子I - IX与Nova2 mRNA之间存在强相关性。此外，通过L型电压依赖性钙通道诱发的钙信号促进了Bdnf外显子I - IX前体mRNA的剪接。值得注意的是，在本研究中所研究的Bdnf前体mRNA剪接中，在Bdnf外显子I - IX前体mRNA中观察到了神经元选择性和活性依赖性剪接。总之（Bdnf外显子I - IX前体mRNA剪接在神经元中优先观察到，并以活性依赖的方式促进。Bdnf外显子I - IX前体mRNA的神经元选择性和活性依赖性剪接可能有助于在神经元中有效诱导Bdnf外显子I - IX的表达。）
括号内为重复内容，原文最后一段出现了两次，翻译时保留了重复部分。
