A Simple Method to Analyze Context- and Tissue-Specific Cis-Regulatory Modulations of Homeotic (HOX) Genes Using ChIP

Homeobox genes (HOX), the master regulators, deploy a unique set of target genes to coordinate and orchestrate the spatiotemporal development of an organism. HOX encoded transcriptional factors regulate the expression of target genes by binding to the specific sequences on the genome. Chromatin Immunoprecipitation (ChIP) and Chromatin Immunoprecipitation with Sequencing (ChIP-Seq) are widely used to map and understand specific gene locus and global regulatory regions on the genome. ChIP is a powerful technique of cross-linking the proteins bound to the DNA, fragmenting DNA to the desired size, and pulling them down using specific antibodies to enrich and analyze the protein-bound DNA. Based on the mapping information, a differential ChIP can be performed to understand cis-regulatory modulations at a defined locus by two developmental stages. This chapter describes the differential ChIP used to identify new targets by comparing two different developmental stages simultaneously using Drosophila melanogaster.