Abstract

BackgroundMethylation-sensitive restriction enzymes—polymerase chain reaction (MSRE-PCR) has been used in epigenetic research to identify genome-wide and gene-specific DNA methylation. Currently, epigenome-wide discovery studies provide many candidate regions for which the MSREqPCR approach can be very effective to confirm the findings. MSREqPCR provides high multiplexing capabilities also when starting with limited amount of DNA-like cfDNA to validate many targets in a time- and cost-effective manner. Multiplex design is challenging and cumbersome to define specific primers in an effective manner, and no suitable software tools are freely available for high-throughput primer design in a time-effective manner and to automatically annotate the resulting primers with known SNPs, CpG, repeats, and RefSeq genes. Therefore a robust, powerful, high-throughput, optimized, and methylation-specific primer design tool with great accuracy will be very useful.ResultsWe have developed a novel pipeline, called MSRE-HTPrimer, to design MSRE-PCR and genomic PCR primers pairs in a very efficient manner and with high success rate. First, our pipeline designs all possible PCR primer pairs and oligos, followed by filtering for SNPs loci and repeat regions. Next, each primer pair is annotated with the number of cut sites in primers and amplicons, upstream and downstream genes, and CpG islands loci. Finally, MSRE-HTPrimer selects resulting primer pairs for all target sequences based on a custom quality matrix defined by the user. MSRE-HTPrimer produces a table for all resulting primer pairs as well as a custom track in GTF file format for each target sequence to visualize it in UCSC genome browser.ConclusionsMSRE-HTPrimer, based on Primer3, is a high-throughput pipeline and has no limitation on the number and size of target sequences for primer design and provides full flexibility to customize it for specific requirements. It is a standalone web-based pipeline, which is fully configured within a virtual machine and thus can be readily used without any configuration. We have experimentally validated primer pairs designed by our pipeline and shown a very high success rate of primer pairs: out of 190 primer pairs, 71 % could be successfully validated. The MSRE-HTPrimer software is freely available from http://sourceforge.net/p/msrehtprimer/wiki/Virtual_Machine/ as a virtual machine.Electronic supplementary materialThe online version of this article (doi:10.1186/s13148-016-0190-9) contains supplementary material, which is available to authorized users.

Highlights

  • Methylation-sensitive restriction enzymes—polymerase chain reaction (MSRE-PCR) has been used in epigenetic research to identify genome-wide and gene-specific DNA methylation

  • MSRE-HTPrimer is an open-source, portable, webbased, and easy-to-use pipeline, which facilitates the design of primer pairs for epigenetic and genomic target validation studies

  • MSRE-HTPrimer provides significant improvements over existing solutions with following unique features: (1) visualization of primer pairs in UCSC genome browser [22], (2) search each resulting primer pair in UCSC In-Silico PCR database [23], (3) flexible primer selection and filtering based on custom quality matrix, and (4) parallel primer design for several target sequences

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Summary

Introduction

Methylation-sensitive restriction enzymes—polymerase chain reaction (MSRE-PCR) has been used in epigenetic research to identify genome-wide and gene-specific DNA methylation. MSREqPCR in contrast to bisulfite PCR can be used for the rapid, simultaneous detection of DNA methylation in multiple fragments when only a limited amount of DNA is available It is a procedure based on the fact that digestion of genomic DNA with methylation-sensitive restriction enzymes is blocked when methylated. MSREqPCR-based method allows for a high level of multiplexing with manageable efforts regarding assay optimization, and only a few nanograms of DNA (10– 20 ng) are needed per 100 assays [5] This method has some limitations such as (1) all CpGs without having the cut site for MSRE cannot be analyzed and (2) single C-resolution is not feasible for the assays with more than one cut sites in CpG and one has to assume that investigated regions are homogenously methylated, which is a common assumption in epigenetics [6]. The total percent coverage of CpGs for these four enzymes is about 39 % (AciI, 17.4 %; Hin6I, 6.4 %; HpaII, 8.6 %; and HpyCH4IV, 6.6 %) of the whole human genomic DNA (Table 2) [4]

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