"SIT" with Emx1-NuTRAP Mice: Simultaneous INTACT and TRAP for Paired Transcriptomic and Epigenetic Sequencing

Epigenetic regulation of transcription is gaining increasing importance in the study of neurobiology. The advent of sequencing technology has enabled the study of this regulation across the entire genome and transcriptome. However, modern methods that allow the correlation of transcriptomic data with epigenomic regulation have had several key limitations, including use of separate tissue sources and detection of low-expression genes. This article describes a method combining isolation of nuclei tagged in specific cell types (INTACT) with translating ribosome affinity purification (TRAP) in the same cell homogenate, referred to as Simultaneous INTACT and TRAP (SIT). We used this technical approach to directly couple transcriptomic sequencing with epigenomic data in neurons derived from the mouse hippocampus. We demonstrate this method with an Emx1-NuTRAP transgenic mouse model. Here, we present protocols for SIT and for the generation and validation of the Emx1-NuTRAP mouse model that we used to demonstrate SIT. These methods enable cell type-specific comparison of translating mRNA and chromatin data from the same set of cells. Using SIT and the Emx1-NuTRAP transgenic mouse model, researchers can compare epigenomic data to transcriptomic data in the same set of hippocampal excitatory neurons. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Emx1-NuTRAP transgenic mouse line for labeling excitatory neurons in the hippocampus Basic Protocol 2: SIT: Simultaneous Isolation of nuclei tagged in specific cell types (INTACT) and Translating ribosome affinity purification (TRAP).