Chromatin immunoprecipitation for identifying transcription factor targets in keratinocytes.

Protein-DNA interactions, such as those that are necessary for transcription, are critical in regulating cellular function and behavior. The identification of DNA sequences that interact with transcriptional regulatory proteins is an important step necessary to better understand the molecular mechanisms regulating gene expression. Chromatin immunoprecipitation (ChIP) is one such procedure that provides a snapshot of which transcription factors are occupying specific DNA sequences. This method allows one not only to determine whether a particular genomic region is occupied by transcription factors but also to identify specific regulatory sequences that potentially control expression of their target genes. Recently, ChIP has been combined with both microarray analysis and a new generation of sequencing allowing a true genome-wide examination of transcription factor binding. Identifying the exact DNA sequence that a transcriptional regulatory protein binds, the precise timing of this association, and what other factors are involved in these interactions are important steps that will shed light on the transcriptional control mechanisms that dictate the biology of all cells, including keratinocytes.