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MotifRaptor

Overview

Motivation:

Genome-wide association studies (GWAS) have identified thousands of common trait-associated genetic variants but interpretation of their function remains challenging. These genetic variants can overlap the binding sites of transcription factors (TFs) and therefore could alter gene expression. However, we currently lack a systematic understanding on how this mechanism contributes to phenotype.

Results:

We present Motif-Raptor, a TF-centric computational tool that integrates sequence-based predic-tive models, chromatin accessibility, gene expression datasets and GWAS summary statistics to systematically investigate how TF function is affected by genetic variants. Given trait associated non-coding variants, Motif-Raptor can recover relevant cell types and critical TFs to drive hy-potheses regarding their mechanism of action. We tested Motif-Raptor on complex traits such as rheumatoid arthritis and red blood cell count and demonstrated its ability to prioritize relevant cell types, potential regulatory TFs and non-coding SNPs which have been previously characterized and validated.

Installation

  1. Set channells

conda config --add channels defaults conda config --add channels bioconda conda config --add channels conda-forge

  1. Install from Bioconda

    conda create -n motifraptor_env python=3.6
    conda activate motifraptor_env
    conda install -c bioconda motifraptor
    
  2. Simple test

    Activate the conda environment before running the program.

    source activate motifraptor_env
    

    Motif Raptor supports two different ways to run it.

    (1) Run from the command line (recommended)

    MotifRaptor --version
    

    (2) Load as a module

    python
    >>>import MotifRaptor
    >>>MotifRaptor.__version__
    

    If you see the version number, congratulations!

Motif-Raptor Modules Overview

MotifRaptor --help
usage: MotifRaptor [-h] [--version]
                
                {preprocess,preprocess_ukbb_v3,celltype,snpmotif,snpfeature,motiffilter,motifspecific,snpspecific,snpmotifradar,snpindex,snpscan,set,info}
                ...

Analyze motifs and SNPs in the dataset.

positional arguments:
{preprocess,preprocess_ukbb_v3,celltype,snpmotif,snpfeature,motiffilter,motifspecific,snpspecific,snpmotifradar,snpindex,snpscan,set,info}
                     help for subcommand: celltype, snpmotif, snpfeature,
                     motiffilter, motifspecific, snpspecific
 preprocess          Pre-process the summary statistics
 preprocess_ukbb_v3  Pre-process the summary statistics from UKBB version 3
                     TSV files
 celltype            cell type or tissue type analysis help
 snpmotif            snp motif test help
 snpfeature          snp feature help
 motiffilter         motifs filtering help
 motifspecific       motifs specific analysis help
 snpspecific         SNP specific analysis help
 snpmotifradar       SNP motif radar plot help
 snpindex            index the SNPs (with flanking sequences) help
 snpscan             scan SNP database (already indexed) help
 set                 Set Path and Global Values
 info                Get Informationa and Print Global Values

optional arguments:
-h, --help            show this help message and exit
--version             show program's version number and exit
 

Configure Essential Databases

Database contains essential data for general analysis, including DHS tracks, TF RNA-seq expressions, TF motifs, and TF pre-calucated scores.

Please download the Database.zip from the links shown below. You can choose to download either a testing database or a complete database. The testing database contains all necessary files except that it only includes a handful number of TFs, in order for you to test the tutorial example on a regular machine. The complete database contains a complete list of TFs used in our real-world study, however, you need to have at least 220 G disk space, and we recommend running the programs on a cluster.

You may also choose to download the testing database, and then refer to the section Build complete motif database to compute a full TF list on your own, rather than downloading a big file. In this case, we also recommend running the programs on a cluster.

# A testing database can be downloaded here.
wget https://www.dropbox.com/s/gxeyzgl5m0u55w8/Database.zip
unzip Database.zip
# A complete database can be downloaded here. Make sure you have 220 G disk space.
wget https://www.dropbox.com/s/kp5r82x55tfgawf/Database.zip
unzip Database.zip

Configuration for Motif-Raptor is to set up the absolute paths for general database and motif database.

MotifRaptor set -pn databasedir -pv $PWD/Database/hg19/
MotifRaptor set -pn motifdatabasedir -pv $PWD/Database/hg19/motifdatabase/

Double check the paths are correctly set up.

MotifRaptor info

*For the current database, we only support human genome hg19. The genomic sequence is originally downloaded from UCSC (http://hgdownload.cse.ucsc.edu/goldenpath/hg19/bigZips/hg19.2bit). *

Skip the next section if you are only doing an example tutorial without changing the TF motif set.

Build a Complete Motif Database

You need this section only when you haven't downloaded the full version of the database with large amount of data in motifdatabase (from previous steps); rather, you would like to pay computing hours to calculate from scratch

(1) Download pfm files and change the motif database directory immediately. (Motif database is a folder that contains a set of TF motif files with JASPAR PFM format.)

wget https://www.dropbox.com/s/hx9av7o16efxmus/motifdatabase.zip
unzip motifdatabase.zip
MotifRaptor set -pn motifdatabasedir -pv $PWD/motifdatabase

Motif-Raptor expects in input TF motif matrices in JASPAR PFM format. TF matrices in this format are stored as simple text flat files e.g.:

A [13 13 3 1 54 1 1 1 0 3 2 5 ]
C [13 39 5 53 0 1 50 1 0 37 0 17 ]
G [17 2 37 0 0 52 3 0 53 8 37 12 ]
T [11 0 9 0 0 0 0 52 1 6 15 20 ]

However TF matrices in other formats (e.g. MEME, TRANSFAC ) can be easily converted to this format with a simple text editor or in batch using the excellent Biopython library. This library offers several well documented parser that can be used for this task, see https://biopython.org/docs/1.75/api/Bio.motifs.html for more information.

(2) Download SNP list from 1000 Genome project

wget https://www.dropbox.com/s/9gztf4mdblc44jo/1000G.EUR.QC.plink.simple.vcf

The SNP list VCF file needs to have the first five columns ('CHR','POS','ID','REF','ALT') as follows:

CHR POS ID REF ALT
1 2483961 rs2258734 A G

(3) Index the SNP list (genome_index is the output folder name which will be also used in next step.) In this step, you will retrieve the flanking sequences centered by each SNP in order to generate indices files using the hg19 genome from the database (currently we only support hg19 as described before, so the vcf file should be also consistent with hg19)

MotifRaptor snpindex -vcf 1000G.EUR.QC.plink.simple.vcf -gi genome_index -p 4

(4) Scan motifs usnig pfm files on this SNP list

MotifRaptor snpscan -gi genome_index -pfm ./motifdatabase/pfmfiles -mo ./motifdatabase/motifscanfiles -p 4

In the output folder, only '.scale' and '.score' files are useful. You may delete intermediate results in those folders.

cd motifdatabase/motifscanfiles/
find ./ -type d -exec rm -rf '{}' \;

Tutorial

step 0. prepare input data (pre-processing) from GWAS summary statistics

Input: GWAS Summary Statistics Run Motif-Raptor from GWAS summary statistics. You may get summary statistics from UKBiobank, published paper, or other resources. These files may provide diffrent information. Please make sure the file contains the following columns. For the score column, Motif-Raptor currently supports pvalue, zscore, or chisquare.

ID CHR POS REF ALT SCORE(pvalue, zscore, or chisquare)
rs2258734 1 2483961 A G 0.003

Example: Download the original data file from (Okada et al. 2010 Nature), and applying your own p-value cut-offs to define hits and nonhits. By default, p-value cutoff is 5E-8. This data file is ~450M. If your internet is limited, please download the zip file (~100M) and unzip it.

wget https://www.dropbox.com/s/jnmpu63vqnlc0ig/RA_GWASmeta_TransEthnic_v2.txt

#alternative zip file
wget https://www.dropbox.com/s/c194x1z0bhntfbs/RA_GWASmeta_TransEthnic_v2.zip
unzip RA_GWASmeta_TransEthnic_v2.zip

In this file, columns 1,2,3,4,5,9 are ID,CHR,POS,REF,ALT,SCORE as defined above. Here the score is pvalue.

MotifRaptor preprocess -gwas RA_GWASmeta_TransEthnic_v2.txt -cn 1,2,3,4,5,9 -st pvalue -th 5E-8

Output: Information for SNP hits and non-hits. hitSNP_list.txt nonhitSNP_list.txt and hitSNP_list.vcf For the example from (Okada et al. 2010 Nature), you can also download our processed results, if you haven't run on your own.

wget https://www.dropbox.com/s/gpnudp1ba4d2gq3/hitSNP_list.txt
wget https://www.dropbox.com/s/7dfrph1dnrad894/nonhitSNP_list.txt
wget https://www.dropbox.com/s/73seqi42hgodupg/hitSNP_list.vcf

Double Check Output Format: hitSNP_list.txt and nonhitSNP_list.txt are two files with the following format:

ID CHR POS
rs2258734 1 2483961

hitSNP_list.vcf is the file with the following format (with two more columns of the polymorphism information:

ID CHR POS REF ALT
rs2258734 1 2483961 A G

Usage:

usage: MotifRaptor preprocess [-h] [-gwas SUMMARYSTATSFILE]
                           [-cn COLUMN_NUMBERS] [-st SCORE_TYPE]
                           [-th SCORE_PVALUE_THRESHOLD]

optional arguments:
-h, --help            show this help message and exit
-gwas SUMMARYSTATSFILE, --gwas_summary SUMMARYSTATSFILE
                     GWAS summary statistic file
-cn COLUMN_NUMBERS, --column_numbers COLUMN_NUMBERS
                     provide six column numbers for information in such
                     order: ID,CHR,POS,A1,A2,SCORE eg. 1,2,3,4,5,6
-st SCORE_TYPE, --score_type SCORE_TYPE
                     Score type in GWAS summary statistic file: pvalue or
                     zscore or chisquare
-th SCORE_PVALUE_THRESHOLD, --threshold SCORE_PVALUE_THRESHOLD
                     threads for pvalue - default 5E-8

Bonus function:

Motif-Raptor allows user to preprocess from the UKBB (v3) summary statistics TSV files directly using a much simpler command.

wget https://www.dropbox.com/s/axthfv12j7pbav4/30690_raw.gwas.imputed_v3.both_sexes.tsv
MotifRaptor preprocess_ukbb_v3 -gwas 30690_raw.gwas.imputed_v3.both_sexes.tsv -th 5E-8

step1. run cell type or tissue type characterization

Example:

MotifRaptor celltype -vcf hitSNP_list.vcf -sh hitSNP_list.txt -sn nonhitSNP_list.txt -wd step1_out/ -p 3

Input: Three input files from step0. Output: This visualization ranks the associated cell or tissue types by both p-values (bar length) and odd ratio (numbers behind the bar). Original text file is "all_sorted.pvalue"

drawing

Optional step:

Motif raptor also provide module interface to run it in your own python code or Jupyter notebook for lightweight task. For example, you can re-plot the figure after running the previous steps.

 #optional: plot figure using module CellTypeAnlayzer after running the command
 from MotifRaptor.CellTypeAnalyzer import CellTypeAnalysis
 CellTypeAnalysis.plotfigure_main("step1_out/testcelltype/all_sorted.pvalue","plot_all_cell_type.pdf")

Usage:

MotifRaptor celltype --help

usage: MotifRaptor celltype [-h] [-vcf SNP_HIT_VCF] [-sh SNP_HIT]
                         [-snh SNP_NON_HIT] [-wd WORKDIR] [-p THREAD_NUM]

optional arguments:
-h, --help            show this help message and exit
-vcf SNP_HIT_VCF, --snp_hit_withseq SNP_HIT_VCF
                     need header and columns in this text file with
                     sequence (CHR is only a number): ID CHR POS REF ALT
-sh SNP_HIT, --snp_hit SNP_HIT
                     need header and columns in this text file (CHR is only
                     a number): ID CHR POS
-snh SNP_NON_HIT, --snp_non_hit SNP_NON_HIT
                     need header and columns in this text file (CHR is only
                     a number): ID CHR POS
-wd WORKDIR, --workdir WORKDIR
                     Working directory
-p THREAD_NUM, --threads THREAD_NUM
                     number of threads

step2. run motif discovery and filtering

step2.1 run through statistics and essential analysis

#run through the motif scan on all the SNPs
MotifRaptor snpmotif -wd step2_out -c "CD8-positive, alpha-beta T cell" \
-sb step1_out/hitSNP_DHSunion_list.bed -se step1_out/hit_snps_seq_pickle.df.txt -bg genome \
-m all -p 3

Input: The bed file for SNP hits and the sequence information are obtained from Step1 "cell type characterization". But you need to determine the background and the motifs you want to test.

You may use "genome" in "-g" to use genome wide SNPs as the baseline distribution. You may use "all" in "-m" to test all of the Transcription Factors collected in the database. But you may specificy a file test_motif.txt to run a test for only a few Transcription Factors. Each motif should take a line, with the format of "motifID__motifname" which pwm files can be found in the Database. For example:

 MA0105.1__NFKB1
 MA0518.1__Stat4

Output: Scores for SNP hits are calculated as text files, including a huge background folder. The outcome of this partial step is not viewable. You need to run the next step to get a summazied text and figures.

Usage:

MotifRaptor snpmotif --help
usage: MotifRaptor snpmotif [-h] [-wd WORKDIR] [-c CELL_TYPE]
                         [-sb HIT_SNP_UNION_BED] [-se HIT_SNP_UNION]
                         [-bg BG_SNPS] [-m MOTIF_LIST] [-p THREAD_NUM]

optional arguments:
-h, --help            show this help message and exit
-wd WORKDIR, --workdir WORKDIR
                     Working directory
-c CELL_TYPE, --cell_type CELL_TYPE
                     Cell type or Tissue type ID
-sb HIT_SNP_UNION_BED, --snp_hit_bed HIT_SNP_UNION_BED
                     hit snps on union bed file, usually from step1
-se HIT_SNP_UNION, --snp_hit_seq HIT_SNP_UNION
                     hit snps with sequence information, usually from step1
-bg BG_SNPS, --bg_snp BG_SNPS
                     background snp list file or (genome)
-m MOTIF_LIST, --motifs MOTIF_LIST
                     motif list file, no header, or (all)
-p THREAD_NUM, --threads THREAD_NUM
                     number of threads

step2.2 apply the summary, filter and plot figures

step2.2.1 apply filter on TF summary file and visualize the TF plots

Example:

#calculate statistics for each transcription factor and apply filtering (i.e. expression and pvalue)
MotifRaptor motiffilter -wd step2_out/motif_result -ms step2_out/motif_result/all_motifs.pvalue

Input: Just specify the working directory from previous step.

Output: The visualization shows the distribution and scoring for the Transcription Factors and narrow down (zoomed in) with the significant/interesting ones.

all motifs

drawing

zoomed in motifs

drawing

Usage:

MotifRaptor snpfeature -h
usage: MotifRaptor snpfeature [-h] [-wd WORKDIR] [-c CELL_TYPE]
                           [-cb SNP_BED_FILES]

optional arguments:
-h, --help            show this help message and exit
-wd WORKDIR, --workdir WORKDIR
                     Working directory
-c CELL_TYPE, --cell_type CELL_TYPE
                     Cell type or Tissue type ID
-cb SNP_BED_FILES, --snp_bed_files SNP_BED_FILES
                     SNP cell type bed file folder, usually from step1
step2.2.2 pre-calculate the SNP-wise features to prepare visualization in the next steps
#calculate SNP wise features (prepare for step3)
MotifRaptor snpfeature -wd step2_out -c "CD8-positive, alpha-beta T cell" -cb step1_out/testcelltype/bedfiles

Input: Just specify the working directory from previous step.

Output: The SNP-wise annotations will be added to the folder.

Usage:

MotifRaptor snpfeature -h
usage: MotifRaptor snpfeature [-h] [-wd WORKDIR] [-c CELL_TYPE]
                           [-cb SNP_BED_FILES]

optional arguments:
-h, --help            show this help message and exit
-wd WORKDIR, --workdir WORKDIR
                     Working directory
-c CELL_TYPE, --cell_type CELL_TYPE
                     Cell type or Tissue type ID
-cb SNP_BED_FILES, --snp_bed_files SNP_BED_FILES
                     SNP cell type bed file folder, usually from step1

step3. SNP and TF events visualization

step3.1 TF specific plot

Example:

  # per motif analysis
 MotifRaptor motifspecific \
 -wd step3_out \
 -sm step2_out/result_new_df_motifs_ENCFF512IML.txt \
 -md MA0105.1__NFKB1 \
 -bs step2_out/motif_result/background_files/
 

Input: Just specify the output directory from step2.

Output: Scatter plot for both SNP hits and non-hits for a picked motif.

drawing

Usage:

usage: MotifRaptor motifspecific [-h] [-wd WORKDIR] [-sm SNP_MOTIF_FILE]
                                 [-md MOTIF_ID_NAME] [-bs BG_SCORE_FOLDER]

optional arguments:
  -h, --help            show this help message and exit
  -wd WORKDIR, --workdir WORKDIR
                        Working directory
  -sm SNP_MOTIF_FILE, --snp_motif_file SNP_MOTIF_FILE
                        SNP motif pair-wise list File, usually from step2
  -md MOTIF_ID_NAME, --motif_id MOTIF_ID_NAME
                        motif id with name, in the format of motifID__NAME
  -bs BG_SCORE_FOLDER, --bg_score_folder BG_SCORE_FOLDER
                        background score folder, usually from step2

step3.2 SNP specific plot

Example:

 # per SNP analysis
MotifRaptor snpspecific \
-wd step3_out \
-sm step2_out/result_new_df_motifs_ENCFF512IML.txt \
-snp rs7528684 

Input: Just specify the output directory from step2.

Output: Scatter plot for transcription factors for a picked SNP.

drawing

Usage:

usage: MotifRaptor snpspecific [-h] [-wd WORKDIR] [-sm SNP_MOTIF_FILE]
                               [-snp SNP_ID]

optional arguments:
  -h, --help            show this help message and exit
  -wd WORKDIR, --workdir WORKDIR
                        Working directory
  -sm SNP_MOTIF_FILE, --snp_motif_file SNP_MOTIF_FILE
                        SNP motif pair-wise list File, usually from step2
  -snp SNP_ID, --snp_id SNP_ID
                        SNP id

step3.3 SNP-TF radar plot

Example:

 # draw radar plot for instereing motif and SNP events
MotifRaptor snpmotifradar \
-wd step3_out \
-sm step2_out/result_new_df_motifs_ENCFF512IML.txt \
-sf step2_out/SNP_ENCFF512IML_features.txt \
-pid rs7528684:MA0105.1__NFKB1

Input: Just specify the output directory from step2.

Output: Radar plot for the features/scores for interesting SNP-motif events.

drawing

Usage:

usage: MotifRaptor snpmotifradar [-h] [-wd WORKDIR] [-sm SNP_MOTIF_FILE]
                                 [-sf SNP_FEATURE_FILE] [-pid SNP_MOTIF_ID]

optional arguments:
  -h, --help            show this help message and exit
  -wd WORKDIR, --workdir WORKDIR
                        Working directory
  -sm SNP_MOTIF_FILE, --snp_motif_file SNP_MOTIF_FILE
                        SNP motif pair-wise list File, usually from step2
  -sf SNP_FEATURE_FILE, --snp_feature_file SNP_FEATURE_FILE
                        SNP feature file, usually from step2
  -pid SNP_MOTIF_ID, --snp_motif_id SNP_MOTIF_ID
                        SNP motif pair-wise ID

Integration with other tools

We also provide a Jupyter Notebook to show how to integrate DeepBind (or other external tools) in the step 2 of Motif-Raptor.

https://github.com/pinellolab/MotifRaptor/blob/master/Document/Supplementary_Data_File_1.ipynb

All the supporting files can be downloaded from this archive:

https://github.com/pinellolab/MotifRaptor/raw/master/Document/deepbind_example.zip

Conclusion

In summary, Motif-Raptor is a computational toolkit to test the significance of the effects of genetic variants from GWAS analyses on transcription factor binding sites. We believe that its adoption will help the genomic community in prioritizing potential cell type-specific, causal variants from GWAS summary statistics and to generate important hypotheses and insights to the mechanisms of action of genetic variants in complex disease.

Contact

Luca Pinello: lpinello at mgh.harvard.edu

Qiuming Yao: yao.ornl at gmail.com

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Explore the effect of genetic variants on transcription factor binding sites

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