TU-tagging: cell type–specific RNA isolation from intact complex tissues

Expressing uracil phosphoribosyltransferase in specific tissues in the fly allows the incorporation of 4-thiouracil into newly synthesized RNA in vivo . The thio-labeled RNA can then be isolated and analyzed by routine procedures allowing the cell type–specific measure of RNA synthesis and decay rates. We found that the combination of spatially restricted uracil phosphoribosyltransferase (UPRT) expression with 4-thiouracil delivery can be used to label and purify cell type–specific RNA from intact complex tissues in Drosophila melanogaster . This method is useful for isolating RNA from cell types that are difficult to isolate by dissection or dissociation methods and should work in many organisms, including mammals and other vertebrates.