We describe a method for visualizing mRNAs in living mouse. Nascent transcripts and cytoplasmic mRNAs were labeled via lentiviral expression of MS2 coat protein (MCP) tagged with fluorescent protein (MCP-XFP) in knock-in mice whose β-actin mRNAs contained MCP binding stem loops (MBS). Then the mRNA molecules were imaged in the live cerebral cortex through an optical cranial window by intravital two-photon microscopy. By means of the controlled expression of MCP-XFP, single mRNA particles could be detected differentially in the nucleus and cytoplasm of a specific cell type. Consequently, this method is useful for investigating the cell-type-dependent dynamics of mRNAs underlying the structure and function of the brain.

中文翻译：

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活体小鼠脑中 mRNA 的成像细胞类型特异性动力学

我们描述了一种在活体小鼠中可视化 mRNA 的方法。新生转录物和细胞质 mRNA 通过在敲入小鼠中标记荧光蛋白 (MCP-XFP) 的 MS2 外壳蛋白 (MCP) 的慢病毒表达进行标记，其 β-肌动蛋白 mRNA 含有 MCP 结合茎环 (MBS)。然后通过活体双光子显微镜通过光学颅窗在活的大脑皮层中对 mRNA 分子进行成像。通过 MCP-XFP 的受控表达，可以在特定细胞类型的细胞核和细胞质中差异检测单个 mRNA 颗粒。因此，该方法可用于研究作为大脑结构和功能基础的 mRNA 的细胞类型依赖性动力学。