A rapid <i>in vivo</i> assay to study the regulation of gene expression

Traditional in vivo studies of gene regulation often require labor-intensive protocols and animal sacrifice. Here, we present a minimally invasive method-In Vivo Imaging of Subcutaneous Luminescence (IVISc-L)-for analyzing gene regulation in live mice. The assay involves subcutaneous injection of plasmid DNA encoding firefly luciferase, the expression of which is controlled by the regulatory mechanism under investigation. Luminescence from the injection site is detected and quantified noninvasively using an in vivo imaging system within 24 h. We demonstrate the utility of this approach to study promoter activity, microRNA-mediated regulation, stop codon readthrough, and rare codon effects. IVISc-L eliminates the need for tissue extraction, offering a rapid and scalable platform for investigating gene expression dynamics and screening gene regulatory modulators in vivo.