Experiment / E6JHO9MMZStandard STARR-seq

Cgt GBS flank synthetic STARR-seq library

Synthetic STARR-seq reveals how DNA shape and sequence modulate transcriptional output and noise

An episomal synSTARR-seq library varied five consecutive flanking nucleotides around a fixed Cgt glucocorticoid receptor binding sequence, representing 1,024 designed flank variants. U2OS-GR cells were treated with 1 µM dexamethasone or 0.1% ethanol vehicle for 4 h in three biological replicates per condition, and all 1,024 released variant-level results passed package QC.

Processed tables are specific to each experiment. Column names, units, measurements, and table structure are not standardized across the database. Check this experiment’s column definitions and quality-control notes before comparing or combining data.

Perturbation & assay details

1 µM dexamethasone for 4 h versus 0.1% ethanol vehicle control

Synthetic STARR-seq (synSTARR-seq) used synthetic oligos cloned into an episomal human STARR-seq reporter downstream of a minimal promoter, so active inserts were quantified through self-transcribing reporter RNA. The Cgt library contains a fixed 15 bp context followed by five randomized flank bases. Five million U2OS-GR cells were nucleofected with 5 µg library DNA, treated the next day with 1 µM dexamethasone or 0.1% ethanol for 4 h, and sequenced using Illumina 50 bp paired-end reads. Reads were retained only when they exactly matched the expected synthetic insert length and nucleotide composition; duplicate reads were intentionally retained for quantitative sequence-level counting. DESeq2 compared dexamethasone and vehicle counts across three biological replicates per condition.

Processed data

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Visible columns (12 of 12)
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Filters apply to this table only. The CSV download contains the complete processed table; filtered rows are available through the API.

Column dictionary · 12 definitions
element_id
Unique package identifier for the synthetic Cgt flank sequence.
library
Synthetic library label; Cgt_flanks denotes the Cgt glucocorticoid receptor binding sequence flank library.
sequence
Full 20 bp synthetic sequence analyzed by the released DESeq2 table.
variable_sequence
The five randomized flank nucleotides (the source table’s kmer field).
fixed_context
The fixed 15 bp Cgt binding-site context immediately 5′ of the randomized segment.
base_mean
DESeq2 baseMean, the mean normalized read abundance across the analyzed samples.
log2_fold_change
DESeq2 log2 fold change for dexamethasone-treated versus ethanol-vehicle reporter RNA counts.
log2_fold_change_se
DESeq2 standard error for the log2 fold change.
test_statistic
DESeq2 Wald test statistic for the treatment contrast.
p_value
Raw DESeq2 p-value for the treatment contrast.
adjusted_p_value
Benjamini–Hochberg adjusted DESeq2 p-value (padj).
activity_call
Package-derived call: significant_activation when adjusted_p_value < 0.01 and log2_fold_change > 0, significant_negative_effect when adjusted_p_value < 0.01 and log2_fold_change < 0, otherwise not_significant.

Quality control

The authors filtered reads to exact insert matches, retained duplicate reads, and identified differential sequence activity with DESeq2 using adjusted p-value < 0.01. Package QC required a 20 bp A/C/G/T-only sequence with a 5 bp variable segment, unique sequence identifiers, finite baseMean/log2FoldChange/lfcSE/stat/pvalue/padj values, positive baseMean, p-value and adjusted p-value in [0,1], and nonnegative lfcSE. All 1,024 of 1,024 released rows passed these checks and were retained; no additional abundance cutoff was imposed on the flank library.

Curation notes

The ArrayExpress source file All_Cgt-flanks_DESeq2.tab omits the leading sequence name from its header; conversion treated the first token of each data row as sequence and preserved the remaining seven source fields. CVCL:0042 is the parental human U2OS osteosarcoma line; the assayed U2OS-GR derivative stably expresses rat GRα and has no separate Cellosaurus accession identified. The paper’s Cgt flank results classify 189 variants as significantly enhancing and 125 as significantly blunting at adjusted p-value < 0.01, with the remainder neutral by that criterion.

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