Analysis of chromatin-nuclear receptor interactions by laser-chromatin immunoprecipitation

Better defining the dynamics of biomolecular interactions is an important step in understanding molecular biology and cellular processes. DNA-protein interactions, and specifically hormone-triggered DNA-nuclear receptor interactions, are key events which are still poorly understood. To date, the most commonly used approach in studying chromatin interactions is the immunoprecipitation of chemically cross-linked chromatin (ChIP) coupled with single gene or global genomic analyses. Currently, establishing a stable interplay between nucleic acids and proteins (DNA-protein cross-link) is mainly obtained through conventional, diffusion-triggered, chemical methods using formaldehyde. Here we describe an alternative method, called Laser-ChIP (LChIP), for the specific analysis of interactions between chromatin and nuclear receptors driven by a UV laser energy source. Photo-induced cross-linking in LChIP is achieved very rapidly, allowing the study of transient interactions, depending on laser source parameters.