Published: April 19th, 2013
The combination of chromatin immunoprecipitation and ultra-high-throughput sequencing (ChIP-seq) can identify and map protein-DNA interactions in a given tissue or cell line. Outlined is how to generate a high quality ChIP template for subsequent sequencing, using experience with the transcription factor TCF7L2 as an example.
ChIP-sequencing (ChIP-seq) methods directly offer whole-genome coverage, where combining chromatin immunoprecipitation (ChIP) and massively parallel sequencing can be utilized to identify the repertoire of mammalian DNA sequences bound by transcription factors in vivo. "Next-generation" genome sequencing technologies provide 1-2 orders of magnitude increase in the amount of sequence that can be cost-effectively generated over older technologies thus allowing for ChIP-seq methods to directly provide whole-genome coverage for effective profiling of mammalian protein-DNA interactions.
For successful ChIP-seq approaches, one must generate high quality ChIP DNA template to obtain the best sequencing outcomes. The description is based around experience with the protein product of the gene most strongly implicated in the pathogenesis of type 2 diabetes, namely the transcription factor transcription factor 7-like 2 (TCF7L2). This factor has also been implicated in various cancers.
Outlined is how to generate high quality ChIP DNA template derived from the colorectal carcinoma cell line, HCT116, in order to build a high-resolution map through sequencing to determine the genes bound by TCF7L2, giving further insight in to its key role in the pathogenesis of complex traits.
For many years there has been an unmet need to identify the set of genes bound and regulated by a given protein genome wide, in particular those in the transcription factor class.
Odom et al.1 used chromatin immunoprecipitation (ChIP) combined with promoter microarrays to systematically identify the genes occupied by pre-specified transcriptional regulators in human liver and pancreatic islets. Subsequently, Johnson et al.2 developed a large-scale chromatin immunoprecipitation assay based on direct ultra high-throughput DNA sequencing (ChIP-seq) in order to comprehensively map protein-DNA inte....
1. Cross-link Chromatin
Once the chromatin has been sonicated and have been treated with RNase and Proteinase, the samples run on the 2% agarose gel should present a smear with the bulk of the DNA at the desired size. If several different cycles are tested, a gradual decrease in size should be seen as the number of cycles increase (Figure 2).
After completing the immunoprecipitation portion of the protocol the enrichment can either be checked by PCR or real-time PCR. For PCR samples run on an a.......
It is now feasible to carry out a genome-wide profile of protein-DNA interactions association using ChIP-seq, as has been very recently demonstrated with other transcription factors2,3. The key to a successful sequencing outcome is the generation of a high quality chromatin immunoprecipitation DNA template.
Once the DNA template has been generated and ascertained to be adequately enriched, one can then take it in library preparation for subsequent sequencing. For example, one.......
|Name of the reagent
|QIAquick PCR Purification Kit
|GoTaq Hot Start Polymerase
|NanoDrop 1000 Spectrophotometer
|Positive control primer sequences (TCF7L2-1)
Negative control primer sequences (CTRL-1)
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