Locus-Specific Proteomics by TChP: Targeted Chromatin Purification

Here, we show that transcription factors bound to regulatory sequences can be identified by purifying these unique sequences directly from mammalian cells in vivo. Using targeted chromatin purification (TChP), a double-pull-down strategy with a tetracycline-sensitive "hook" bound to a specific promoter, we identify transcription factors bound to the repressed gamma-globin gene-associated regulatory regions. After validation of the binding, we show that, in human primary erythroid cells, knockdown of a number of these transcription factors induces gamma-globin gene expression. Reactivation of gamma-globin gene expression ameliorates the symptoms of beta-thalassemia and sickle cell disease, and these factors provide potential targets for the development of therapeutics for treating these patients.