cmsip

CMSIP: Hydroxymethylation anlaysis of CMS-IP data

A scalable, accurate, and efficient solution for hydroxymethylation analysis of CMS-IP sequencing data.

Installation

CMSIP has been deployed in Bioconda at https://anaconda.org/bioconda/cmsip. It is encouraged to install CMSIP from Bioconda due to most runtime dependencies will be installed automatically. The following channels should be added in Conda. Namely,

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

Alternatively, CMSIP has been also deployed in PyPI at https://pypi.org/project/cmsip, and it can be installed via pip.

pip3 install cmsip

In some cases, users want to build CMSIP manually from source code at https://github.com/lijinbio/cmsip. Below is an example installation steps.

git clone https://github.com/lijinbio/cmsip.git
cd cmsip
python3 setup.py install

In order to run CMSIP after a manual installation, the following dependent software are required.

Software	URL
Python 3	https://www.python.org
Matplotlib	https://matplotlib.org
PyYAML	https://pyyaml.org
bedtools	https://bedtools.readthedocs.io
R software	https://www.r-project.org
R package DESeq2	https://bioconductor.org/packages/release/bioc/html/DESeq2.html
R package genefilter	https://bioconductor.org/packages/release/bioc/html/genefilter.html
R package RVAideMemoire	https://cran.r-project.org/web/packages/RVAideMemoire/index.html
Gawk	https://www.gnu.org/software/gawk
MOABS	https://github.com/sunnyisgalaxy/moabs

Documentation

CMSIP takes in a configuration file for input data and program parameters. CMSIP can be run end-to-end, starting from raw FASTQ files to peak calling and differential hydroxymethylation identification. One can also start the pipeline from intermediate steps. For example, using alignment files as input so that mapping steps will be skipped.

Inspection of configuration

The configuration file is in a YAML format. Two example templates are config_fastq.yaml and config_bam.yaml under https://github.com/lijinbio/cmsip/blob/master/config. config_fastq.yaml is used as a full CMSIP running from FASTQ inputs, while config_bam.yaml is adapted to input existing BAM files so that CMSIP will skip the long-time alignment step. The inspection of configuration is explained below.

1. sampleinfo

The sampleinfo section defines metadata information in analysis. Below metadata information can be specified.

Parameter	Description
sampleinfo.sampleid	the unique identifier to one sample
sampleinfo.group	the biological group of the sample, e.g., KO or WT
sampleinfo.filenames	the absolute path of raw FASTQ files
sampleinfo.reference	the absolute path of the reference BAM file when aligninfo.inputbam is True
sampleinfo.spikein	the absolute path of the spike-in BAM file when aligninfo.inputbam and aligninfo.usespikein is True

1. groupinfo

This section defines biological comparison group1 - group2, e.g., KO - WT.

Parameter	Description
groupinfo.group1	the first group in biological comparison
groupinfo.group2	the second group in biological comparison

1. resultdir

This directory is default working directory storing intemediate result files, such as BAM and BED files.

1. aligninfo

This section specifies parameters used in raw reads alignment.

Parameter	Description
aligninfo.inputbam	True for BAM inputs. Default: FASTQ inputs.
aligninfo.reference	FASTA file of the reference genome, e.g. hg38.fa.
aligninfo.usespikein	True for spike-in libraries, otherwise False. This option controls the normalization method, either a spike-in normalization using spike-in mapping, or reduced to WIG sum in reference genome.
aligninfo.spikein	FASTA file of the spike-in genome, e.g. mm10.fa.
aligninfo.statfile	the output statistics file. This file includes quality control statistics as well as estimated normalization factors.
aligninfo.barplotinfo	a barplot of normalized WIG sums of samples.
aligninfo.numthreads	number of threads in alignment program.
aligninfo.verbose	Print verbose message

1. genomescaninfo

This section defines parameters for CMS measurement construction.

Parameter	Description
genomescaninfo.readextension	True to extend reads length before CMS measurement construction.
genomescaninfo.fragsize	the fixed fragment size to extend when readextension is True.
genomescaninfo.windowfile	an intermediate window file with fixed-size genomic regions.
genomescaninfo.referencename	the UCSC genome name to fetch reference genome size. E.g., hg38 or mm10.
genomescaninfo.windowsize	the window size
genomescaninfo.readscount	CMS measurement using readcount (True) or mean WIG (False).
genomescaninfo.counttablefile	the result count table file.
genomescaninfo.verbose	Print verbose message

1. dhmrinfo

Parameters in this section is for DMR detection.

Parameter	Description
dhmrinfo.method	The statistical method used in DHMR detection. Available methods: ttest, chisq, gtest, nbtest, nbtest_sf. ttest is calling Student's t-test to examine the mean difference of CMS measurements between two biological groups. chisq and gtest are Pearson’s Chi-squared and G-test to test if sums of CMS measurements fit the numbers of replicates between two biological condtions. nbtest applies negative binomial generalized linear model to formulate CMS measurements, and Wald test evaluates the significance of logarithmic fold change. By default, CMS measurement are adjusted by size factors using spike-in normalization. In nbtest_sf, CMS measurements are normalized by the median-ratio algorithm (previously used in DESeq2 for transcriptome measurements).
dhmrinfo.meandepth	Average depth to filter out low-depth windows. This step is essential to save computing resources and increase power of downstream statistical inference
dhmrinfo.testfile	The result file with statistical outputs for whole genome windows
dhmrinfo.qthr	q-value threshod for DHMW.
dhmrinfo.maxdistance	Maximum distance to merge adjacent DHMWs into DHMRs
dhmrinfo.dhmrfile	The final DHMR result file after merging adjacent DHMWs.
dhmrinfo.numthreads	The number of threads.
dhmrinfo.nsplit	The number of split of windows. This option controls parallelization with dhmrinfo.numthreads.
dhmrinfo.verbose	Print verbose message.
dhmrinfo.keepNA	Keep genome windows ruled out by independent filtering.

1. useinput

To indicate if the input data is used during CMS-IP sequencing.

1. inputinfo

If useinput is True, this section is required to specify input data. When input data is used, peak windows are identified first by comparing CMS measurements between group 1/2 and their input data. Then, the union of peak windows are tested for DHMR between group 1 and group 2.

Parameter	Description
inputinfo.group1	The label for the first group input data.
inputinfo.group2	The label for the second group input data. Group 1 and group 2 can share same set of input data.
inputinfo.method	The statistical method used in peak calling. See dhmrinfo.method.
inputinfo.qthr	q-value threshold for peak calling.
inputinfo.testfile1	Statistical test results for group 1 peaking calling.
inputinfo.dhmrfile1	Peak regions for group 1.
inputinfo.testfile2	Statistical test results for group 2 peaking calling.
inputinfo.dhmrfile2	Peak regions for group 2.
inputinfo.inputfilterfile	Union of peak regions in group 1 and group 2.
inputinfo.verbose	Print verbose message.

A toy example using BAM inputs

To facilitate the running of CMSIP, a toy example is generated using existing BAM inputs. The example is accessible at https://github.com/lijinbio/cmsip/blob/master/example. The example directory consists of running scripts and example BAM files. Below commands will generate the configuration file and run the example.

$ ./config.sh ## Generate config.yaml
$ ./fasta.sh ## download the reference genome and the spike-in genome under ./fasta
$ ./run.sh ## run the example

1. config.sh

This script will generate the running configuration file. The inspection of configuration file has been explained above. This example includes small BAM files for 2 KO and 2 WT samples, together with 3 input samples. Spike-in BAM files are also included for spike-in normalization. These BAM files are under the ./bamfile directory. The gtest is used for peaking calling and DHMR detection.

1. fasta.sh

This script is to download required FASTA file for reference genome and spike-in genome. These FASTA files are used in MCALL for bisulfite conversion ratio (BCR) estimation. FASTA files are downloaded into a local directory ./fasta.

1. run.sh

The simple command to run CMSIP:

$ cmsip -c config.yaml

Intermediate and results files are stored under ./outdir. The example quality control statistic file (e.g., qcstats.txt) is as below.

sample_id	total	unique_ref	ref/total	unique_spk	spk/total	comm	comm/total	comm/unique_ref	twss_spk	sizefactors	twss_ref	twss_ref_norm	bcr_ref	bcr_spk
T1	2328	2328	100.00%	141	6.06%	99	4.25%	4.25%	3053	0.52	171892	88620	0.022883	0.278465
T2	20414	20414	100.00%	2780	13.62%	2539	12.44%	12.44%	9522	0.17	704965	116532	0.033482	0.178238
W1	1588	1588	100.00%	97	6.11%	74	4.66%	4.66%	1786	0.88	118312	104268	0.043317	0.206362
W2	1182	1182	100.00%	89	7.53%	66	5.58%	5.58%	1574	1.00	85335	85335	0.034864	0.214435
I1	212	212	100.00%	17	8.02%	4	1.89%	1.89%	992	1.59	15984	25362	0.738502	0.811715
I2	150	150	100.00%	14	9.33%	1	0.67%	0.67%	1032	1.53	11586	17671	0.897633	0.994475
I3	52	52	100.00%	9	17.31%	0	0.00%	0.00%	356	4.42	2053	9077	0.910494	0.983871

Specifically, the sizefactors column is the size factors generated by spike-in normalization.

The example DHMR file is as below.

chrom	start	end	baseMean	lfc	statistic	pvalue	padj
chr4	105276100	105276400	95.88	-0.8072375451	27.63702666	1.463503254e-07	2.048904555e-06
chr4	105272500	105272700	86.7175	-0.837383035	19.45881901	1.027921214e-05	4.796965666e-05
chr4	105259600	105259800	42.4925	-0.5320182773	5.682020984	0.01713961427	0.03999243329

For example, three hypo-DHMRs are identified in chr4 between group T and group W.

Contact

Maintainer: Jin Li, [e-mail]. PI: De-Qiang Sun, [e-mail].