Micro-chromatin immunoprecipation (μChIP) protocol for real-time PCR analysis of a limited amount of cells

Chromatin immunoprecipitation followed by deep sequencing (ChIP-Seq) is an important strategy to study gene regulation. When availability of cells is limited, however, it can be useful to focus on specific genes to investigate in depth the role of transcription factors or histone marks. Unfortunately, performing ChIP experiments to study transcription factors' binding to DNA can be difficult when biological material is restricted. This protocol describes a robust method to perform μChIP for over-expressed or endogenous transcription factors using ~100,000 cells per ChIP experiment (Masserdotti et al., 2015). We also describe optimization steps, which we think are critical for this protocol to work and which can be used to further reduce the number of cells.