Assessing mRNA nuclear export in mammalian cells by microinjection

•mRNA export is a poorly understood step in eukaryotic gene expression.•Microinjection-based assays allow for the accurate measurement of mRNA nuclear export kinetics.•Successful execution of this assay can be aided by implementing certain practices.

The nuclear export of mRNAs is an important yet little understood part of eukaryotic gene expression. One of the easiest methods for monitoring mRNA export in mammalian tissue culture cells is through the microinjection of DNA plasmids into the nucleus and monitoring the distribution of the transcribed product over time. Here we describe how to setup a microscope equipped with a micromanipulator used in cell microinjections, and we explain how to perform a nuclear mRNA export assay and obtain the nuclear export rate for any given mRNA.