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# Transcription Factor ChIP-seq (161 factors) from ENCODE with Factorbook Motifs | ||
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<http://genome.ucsc.edu/cgi-bin/hgTrackUi?db=hg19&g=wgEncodeRegTfbsClusteredV3> | ||
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# Description | ||
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This track shows regions of transcription factor binding derived from a large | ||
collection of ChIP-seq experiments performed by the ENCODE project, together | ||
with DNA binding motifs identified within these regions by the ENCODE | ||
Factorbook repository. | ||
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Transcription factors (TFs) are proteins that bind to DNA and interact with RNA | ||
polymerases to regulate gene expression. Some TFs contain a DNA binding domain | ||
and can bind directly to specific short DNA sequences ('motifs'); others bind | ||
to DNA indirectly through interactions with TFs containing a DNA binding | ||
domain. High-throughput antibody capture and sequencing methods (e.g. chromatin | ||
immunoprecipitation followed by sequencing, or 'ChIP-seq') can be used to | ||
identify regions of TF binding genome-wide. These regions are commonly called | ||
ChIP-seq peaks. | ||
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ENCODE TFBS ChIP-seq data were processed using the computational pipeline | ||
developed by the ENCODE Analysis Working Group to generate uniform peaks of TF | ||
binding. Peaks for 161 transcription factors in 91 cell types are combined here | ||
into clusters to produce a summary display showing occupancy regions for each | ||
factor and motif sites within the regions when identified. Additional views of | ||
the underlying ChIP-seq data and documentation on the methods used to generate | ||
it are available from the ENCODE Uniform TFBS track. | ||
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# Display Conventions | ||
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A gray box encloses each peak cluster of transcription factor occupancy, with | ||
the darkness of the box being proportional to the maximum signal strength | ||
observed in any cell line contributing to the cluster. The HGNC gene name for | ||
the transcription factor is shown to the left of each cluster. Within a | ||
cluster, a green highlight indicates the highest scoring site of a | ||
Factorbook-identified canonical motif for the corresponding factor. (NOTE: | ||
motif highlights are shown only in browser windows of size 50,000 bp or less, | ||
and their display can be suppressed by unchecking the highlight motifs box on | ||
the track configuration page). Arrows on the highlight designate the matching | ||
strand of the motif. | ||
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The cell lines where signal was detected for the factor are identified by | ||
single-letter abbreviations shown to the right of the cluster. The darkness of | ||
each letter is proportional to the signal strength observed in the cell line. | ||
Abbreviations starting with capital letters designate ENCODE cell types | ||
identified for intensive study - Tier 1 and Tier 2 - while those starting with | ||
lowercase letters designate Tier 3 cell lines. | ||
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Click on a peak cluster to see more information about the TF/cell assays | ||
contributing to the cluster, the cell line abbreviation table, and details | ||
about the highest scoring canonical motif in the cluster. | ||
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# Methods | ||
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Peaks of transcription factor occupancy from uniform processing of ENCODE | ||
ChIP-seq data by the ENCODE Analysis Working Group were filtered to exclude | ||
datasets that did not pass the integrated quality metric (see "Quality Control" | ||
section of Uniform TFBS) and then were clustered using the UCSC hgBedsToBedExps | ||
tool. Scores were assigned to peaks by multiplying the input signal values by a | ||
normalization factor calculated as the ratio of the maximum score value (1000) | ||
to the signal value at one standard deviation from the mean, with values | ||
exceeding 1000 capped at 1000. This has the effect of distributing scores up to | ||
mean plus one 1 standard deviation across the score range, but assigning all | ||
above to the maximum score. The cluster score is the highest score for any peak | ||
contributing to the cluster. | ||
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The Factorbook motif discovery and annotation pipeline uses the MEME-ChIP and | ||
FIMO tools from the MEME software suite in conjunction with machine learning | ||
methods and manual curation to merge discovered motifs with known motifs | ||
reported in Jaspar and TransFac. Motif identifications reported in Wang et al. | ||
2012 (below) were supplemented in this track with more recent data (derived | ||
from newer ENCODE datasets - Jan 2011 through Mar 2012 freezes), provided by | ||
the Factorbook team. Motif identifications from all datasets were merged, with | ||
the most significant value (qvalue) reported being picked when motifs were | ||
duplicated in multiple cell lines. The scores for the selected best-scoring | ||
motif sites were then transformed to -log10. | ||
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# Release Notes | ||
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Release 4 (February 2014) of this track adds display of the Factorbook motifs. | ||
Release 3 (August 2013) added 124 datasets (690 total, vs. 486 in Release 2), | ||
representing all ENCODE TF ChIP-seq passing quality assessment through the | ||
ENCODE March 2012 data freeze. The peaks used to generate these clusters were | ||
called with less stringent thresholds than used during the January 2011 uniform | ||
processing shown in Release 2 of this track. The contributing datasets are | ||
displayed as individual tracks in the ENCODE Uniform TFBS track, which is | ||
available along with the primary data tracks in the ENC TF Binding Supertrack | ||
page. The clustering for V3/V4 is based on the transcription factor target, and | ||
so differs from V2 where clustering was based on antibody. | ||
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For the V3/V4 releases, a new track table format, 'factorSource' was used to | ||
represent the primary clusters table and downloads file, | ||
wgEncodeRegTfbsClusteredV3. This format consists of standard BED5 fields (see | ||
File Formats) followed by an experiment count field (expCount) and finally two | ||
fields containing comma-separated lists. The first list field (expNums) | ||
contains numeric identifiers for experiments, keyed to the | ||
wgEncodeRegTfbsClusteredInputsV3 table, which includes such information as the | ||
experiment's underlying Uniform TFBS table name, factor targeted, antibody | ||
used, cell type, treatment (if any), and laboratory source. The second list | ||
field (expScores) contains the scores for the corresponding experiments. For | ||
convenience, the file downloads directory for this track also contains a BED | ||
file, wgEncodeRegTfbsClusteredWithCellsV3, that lists each cluster with the | ||
cluster score followed by a comma-separated list of cell types. | ||
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# Credits | ||
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This track shows ChIP-seq data from the Myers Lab at the HudsonAlpha Institute | ||
for Biotechnology and by the labs of Michael Snyder, Mark Gerstein, Sherman | ||
Weissman at Yale University, Peggy Farnham at the University of Southern | ||
California, Kevin Struhl at Harvard, Kevin White at the University of Chicago, | ||
and Vishy Iyer at the University of Texas, Austin. These data were processed | ||
into uniform peak calls by the ENCODE Analysis Working Group pipeline developed | ||
by Anshul Kundaje The clustering of the uniform peaks was performed by UCSC. | ||
The Factorbook motif identifications and localizations (and valuable assistance | ||
with interpretation) were provided by Jie Wang, Bong Hyun Kim and Jiali Zhuang | ||
of the Zlab (Weng Lab) at UMass Medical School. | ||
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# References | ||
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Gerstein MB, Kundaje A, Hariharan M, Landt SG, Yan KK, Cheng C, Mu XJ, Khurana | ||
E, Rozowsky J, Alexander R et al. Architecture of the human regulatory network | ||
derived from ENCODE data. Nature. 2012 Sep 6;489(7414):91-100. PMID: 22955619 | ||
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Wang J, Zhuang J, Iyer S, Lin X, Whitfield TW, Greven MC, Pierce BG, Dong X, | ||
Kundaje A, Cheng Y et al. Sequence features and chromatin structure around the | ||
genomic regions bound by 119 human transcription factors. Genome Res. 2012 | ||
Sep;22(9):1798-812. PMID: 22955990; PMC: PMC3431495 | ||
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Wang J, Zhuang J, Iyer S, Lin XY, Greven MC, Kim BH, Moore J, Pierce BG, Dong | ||
X, Virgil D et al. Factorbook.org: a Wiki-based database for transcription | ||
factor-binding data generated by the ENCODE consortium. Nucleic Acids Res. 2013 | ||
Jan;41(Database issue):D171-6. PMID: 23203885; PMC: PMC3531197 | ||
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# Data Release Policy | ||
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While primary ENCODE data was subject to a restriction period as described in | ||
the ENCODE data release policy, this restriction does not apply to the | ||
integrative analysis results, and all primary data underlying this track have | ||
passed the restriction date. The data in this track are freely available. |