Histones are subject to numerous covalent modifications, including methylations and acetylations. Multiple histone modifications act in a combinatiorial patterns to specify distinct chromatin states and are heritable. Based on these theories we used the CoSBI algorithm (coherent and shifted bicluster identification algorithm) to analyze the correlation features of 22 histone modifications in Drosophila Melanogaster genome. Furthermore, we analyzed the cooperative action of histone marks associated with RNA polymeraseⅡ,insulator binding protein and gene expression level.
Based on a given epigenome we exhaustively identified the combinatorial patterns of histone modifications by each bicluster. We found some histone combinatorial patterns in Drosophila Melanogaster genome which described cooperative phenomenon of 22 histone modifications. Furthermore, we identified the combinatorial patterns of histone marks associated with RNA polymeraseⅡand insulators binding proteins and found some core histone modifications. The results indicated some special modifications have higher probabilities appeared together in the functional DNA elements. Finally, we applied the algorithm on two gene groups with different activity (expressed and not expressed) respectively. The results showed that acetylations more closely relate to active genes, but methylations relate to inactive genes.
In conclusion, we analyzed the combinational patterns of histone modifications on whole genome and functional DNA elements using the CoSBI algorithm. The results may be able to provide a useful clue to understand the regulatory role of histone modifications in gene expression and disease development, and so on.