Transcriptional reporter systems allow researchers to investigate the function and regulation of transcription factors. Conventional systems employ artificial cDNA overexpression vectors containing either a promoter fragment or specific nucleotide sequence repeats upstream of firefly luciferase or fluorescent reporters, such as green fluorescence protein (GFP) cDNA. These systems suffer mainly from the lack of chromatin context. Here, we describe the rapid generation of endogenous transcriptional reporter cells for the bone morphogenetic protein (BMP) pathway using CRISPR/Cas9 genome editing. In principle, our methodology can be applied to any cell line. The endogenous reporters will provide a robust system for the investigation of BMP transcriptional activity in the context of native chromatin landscape and facilitate chemical and genetic screens.
