PNAS PLUS

Identifying and mapping cell-type-specific chromatin programming of gene expression Troels T. Marstranda and John D. Storeya,b,1 a

Lewis-Sigler Institute for Integrative Genomics, and bDepartment of Molecular Biology, Princeton University, Princeton, NJ 08544

epigenetics encode

| gene regulation | computational biology | association |

H

umans, like all other multicellular organisms, possess a large number of distinct cell types, each of which is specialized for a particular function within the body. Cells from a variety of tissue types exhibit different gene-expression profiles relating to their function, where typically only a fraction of the genome is expressed. As all somatic cells share the same genome, specialization is in part achieved by physically sequestering regions containing nonessential genes into heterochromatin structures. Genes that are needed for the particular task of the cell type display an accessible chromatin structure allowing for the binding of transcription factors and other related DNA machinery and subsequent gene expression. To date, most studies have been limited to considering the chromatin accessibility surrounding the promoter region of genes, which is typically proximal (