Genome-Wide Measurement and Computational Analysis of Transcription Factor Binding and Chromatin Accessibility in Lymphocytes

摘要

Cells of the adaptive immune system, including CD4+ and CD8+ T cells, as well as B cells, possess the ability to undergo dynamic changes in population size, differentiation state, and function to counteract diverse and temporally stochastic threats from the external environment. To achieve this, lymphocytes must be able to rapidly control their gene-expression programs in a cell-type-specific manner and in response to extrinsic signals. Such capacity is provided by transcription factors (TFs), which bind to the available repertoire of regulatory DNA elements in distinct lymphocyte subsets to program cell-type-specific gene expression. Here we provide a set of protocols that utilize massively parallel sequencing-based approaches to map genome-wide TF-binding sites and accessible chromatin, with consideration of the unique aspects and technical issues facing their application to lymphocytes. We show how to computationally validate and analyze aligned data to map differentially enriched/accessible sites, identify enriched DNA sequence motifs, and detect the position of nucle-osomes adjacent to accessible DNA elements. These techniques, when applied to immune cells, can enhance our understanding of how gene-expression programs are controlled within lymphocytes to coordinate immune function in homeostasis and disease.