Imaging cell-type-specific dynamics of mRNAs in living mouse brain.

Highlights • The brain is characterized by the diversity of cell types. • Variability (i.e., noise) in the synthesis and intracellular movement of mRNAs is thought to play a crucial role in regulating the structure and function of the brain. • The dynamics of mRNA is observed in the brain of living mouse, where cellular identities are undisturbed, by intravital two-photon microscopy. • Context-dependent mRNA dynamics can be resolved by engineering viral construct for MBS-MCP. Abstract 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. [ABSTRACT FROM AUTHOR]