title: A code for transcription initiation in mammalian genomes.
abstract: Genome-wide detection of transcription start sites (TSSs) has revealed that RNA Polymerase II transcription initiates at millions of positions in mammalian genomes. Most core promoters do not have a single TSS, but an array of closely located TSSs with different rates of initiation. As a rule, genes have more than one such core promoter; however, defining the boundaries between core promoters is not trivial. These discoveries prompt a re-evaluation of our models for transcription initiation. We describe a new framework for understanding the organization of transcription initiation. We show that initiation events are clustered on the chromosomes at multiple scales-clusters within clusters-indicating multiple regulatory processes. Within the smallest of such clusters, which can be interpreted as core promoters, the local DNA sequence predicts the relative transcription start usage of each nucleotide with a remarkable 91% accuracy, implying the existence of a DNA code that determines TSS selection. Conversely, the total expression strength of such clusters is only partially determined by the local DNA sequence. Thus, the overall control of transcription can be understood as a combination of large- and small-scale effects; the selection of transcription start sites is largely governed by the local DNA sequence, whereas the transcriptional activity of a locus is regulated at a different level; it is affected by distal features or events such as enhancers and chromatin remodeling.
authors.affiliation: Genome Exploration Research Group (Genome Network Project Core Group), RIKEN Genomic Sciences Center, RIKEN Yokohama Institute, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan. martin@cbrc.jp
authors.forename: Martin C
authors.initials: MC
authors.lastname: Frith
authors.forename: Eivind
authors.initials: E
authors.lastname: Valen
authors.forename: Anders
authors.initials: A
authors.lastname: Krogh
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Hayashizaki
authors.forename: Piero
authors.initials: P
authors.lastname: Carninci
authors.forename: Albin
authors.initials: A
authors.lastname: Sandelin
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D042002:Chromatin Assembly and Disassembly / Q000502:physiology*; D002877:Chromosomes, Human / Q000502:physiology*; D030541:Databases, Genetic; D015894:Genome, Human / Q000502:physiology*; D006801:Humans; D008390:Markov Chains; D011401:Promoter Regions, Genetic / Q000502:physiology*; D040641:Quantitative Trait Loci / Q000502:physiology; D012319:RNA Polymerase II / Q000502:physiology*; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic / Q000502:physiology*
chemical_list: D012319:RNA Polymerase II