Institute of Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin, Campus Mitte, 10117 Berlin, Germany.
Bernstein Center for Computational Neuroscience (BCCN) Berlin, 10115 Berlin, Germany.
Int J Mol Sci. 2020 Feb 25;21(5):1567. doi: 10.3390/ijms21051567.
Brain-derived neurotrophic factor (BDNF) is a major neuronal growth factor that is widely expressed in the central nervous system. It is synthesized as a glycosylated precursor protein, (pro)BDNF and post-translationally converted to the mature form, (m)BDNF. BDNF is known to be produced and secreted by cortical glutamatergic principal cells (PCs); however, it remains a question whether it can also be synthesized by other neuron types, in particular, GABAergic interneurons (INs). Therefore, we utilized immunocytochemical labeling and reverse transcription quantitative PCR (RT-qPCR) to investigate the cellular distribution of proBDNF and its RNA in glutamatergic and GABAergic neurons of the mouse cortex. Immunofluorescence labeling revealed that mBDNF, as well as proBDNF, localized to both the neuronal populations in the hippocampus. The precursor proBDNF protein showed a perinuclear distribution pattern, overlapping with the rough endoplasmic reticulum (ER), the site of protein synthesis. RT-qPCR of samples obtained using laser capture microdissection (LCM) or fluorescence-activated cell sorting (FACS) of hippocampal and cortical neurons further demonstrated the abundance of BDNF transcripts in both glutamatergic and GABAergic cells. Thus, our data provide compelling evidence that BDNF can be synthesized by both principal cells and INs of the cortex.
脑源性神经营养因子（BDNF）是一种广泛表达于中枢神经系统的主要神经元生长因子。它作为一种糖基化前体蛋白（proBDNF）被合成，并在翻译后被转化为成熟形式（mBDNF）。BDNF 已知由皮质谷氨酸能主细胞（PC）产生和分泌；然而，它是否也可以由其他神经元类型，特别是 GABA 能中间神经元（IN）合成，仍然是一个问题。因此，我们利用免疫细胞化学标记和反转录定量 PCR（RT-qPCR）来研究小鼠皮质中谷氨酸能和 GABA 能神经元中 proBDNF 及其 RNA 的细胞分布。免疫荧光标记显示 mBDNF 和 proBDNF 均定位于海马体中的神经元群体。前体 proBDNF 蛋白显示出核周分布模式，与蛋白质合成的场所粗面内质网（ER）重叠。使用激光捕获显微切割（LCM）或海马体和皮质神经元的荧光激活细胞分选（FACS）获得的样品的 RT-qPCR 进一步证明了 BDNF 转录本在谷氨酸能和 GABA 能细胞中的丰富程度。因此，我们的数据提供了令人信服的证据，表明 BDNF 可以由皮质的主细胞和 IN 合成。
