Abstract
BackgroundCovalent modifications of histones and histone variants have great influence on chromatin structure, which is involved in the transcriptional regulation of gene expression. Chromatin immunoprecipitation (ChIP) is a powerful tool for studying in vivo DNA-histone interactions. Strawberry is a model for Rosaceae and non-climacteric fruits, in which histone modifications have been implicated to affect fruit development and ripening. However, a validated ChIP method has not been reported in strawberry, probably due to its high levels of polysaccharides which affect the quality of prepared chromatin and the efficiency of immunoprecipitation.ResultsWe describe a native chromatin immunoprecipitation (N-ChIP) protocol suitable for strawberry by optimizing the parameters for nuclei isolation, chromatin extraction, DNA fragmentation and validation analysis using quantitative real-time PCR (qRT-PCR). The qRT-PCR results show that both the active mark H3K36me3 and the silent mark H3K9me2 are efficiently immunoprecipitated for the enriched regions. Compared to X-ChIP (cross-linked chromatin followed by immunoprecipitation), our optimized N-ChIP procedure has a higher signal-to-noise ratio and a lower background for both the active and the silent histone modifications. Furthermore, high-throughput sequencing following N-ChIP demonstrates that nearly 90% of the enriched H3K9/K14ac peaks are overlapped between biological replicates, indicating its remarkable consistency and reproducibility.ConclusionsAn N-ChIP method suitable for the fleshy fruit tissues of woodland strawberry Fragaria vesca is described in this study. The efficiency and reproducibility of our optimized N-ChIP protocol are validated by both qRT-PCR and high-throughput sequencing. We conclude that N-ChIP is a more suitable method for strawberry fruit tissues relative to X-ChIP, which could be combined with high-throughput sequencing to investigate the impact of histone modifications in strawberry and potentially in other fruits with high content of polysaccharides.
Highlights
Covalent modifications of histones and histone variants have great influence on chromatin structure, which is involved in the transcriptional regulation of gene expression
X-Chromatin immunoprecipitation (ChIP) and native chromatin immunoprecipitation (N-ChIP) are the two most commonly used ChIP methods
Nuclei isolation from the strawberry fleshy fruit tissues The procedure of nuclei isolation we performed was based on published protocols with some modifications [13, 19,20,21]
Summary
Covalent modifications of histones and histone variants have great influence on chromatin structure, which is involved in the transcriptional regulation of gene expression. Chromatin immunoprecipitation (ChIP) is a powerful tool for studying in vivo DNA-histone interactions. A validated ChIP method has not been reported in strawberry, probably due to its high levels of polysaccharides which affect the quality of prepared chromatin and the efficiency of immunoprecipitation. Chromatin is composed of DNAs, histones, chromosomal proteins and associated RNAs [1,2,3]. Histone modifications on the N-terminal tails of core histones play an important role in epigenetic regulation, which greatly influences chromatin structures and gene expressions [4, 5]. ChIP is a powerful method that allows one to identify the specific genomic regions associated with a protein of interest. It can be used to locate histones carrying specific covalent modifications, such as acetylation, phosphorylation, or methylation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
