Chromatinsight: machine learning for comparative epigenomics
After finishing my PhD, I moved in 2018 to Newcastle University, looking for new horizons in computational biology. For me, it was bigger the change of moving from proteomics to epigenomics than moving between countries. It meant learning a new data landscape: the basic unit, the starting point, which for me had been mass spectra, became now sequences, a very different way of thinking!
However, the underlying question remained: how can a complex molecular profile be turned into an interpretable comparison? The transition gave me an opportunity to apply the same creative approach (building methods around the structure of the biological problem) in a different field. During my postdoctoral work with Daniel Rico, I developed Chromatinsight to identify epigenomic features that distinguish two groups of samples. The model is based on a random forest algorithm (although this can be replaced by other methods) to learn from chromatin-state segmentations produced with ChromHMM, allowing combinations of marks and genomic contexts to be prioritised without reducing the analysis to one signal at a time.
I built the initial Python implementation and made it available with a tutorial, test data and an open-source licence. A companion R toolkit supports the preparation and exploration of Chromatinsight analyses. The first biological application compared male and female epigenomic profiles, but the design is general: the two groups can represent different conditions, phenotypes or experimental contexts.
Chromatinsight has also continued beyond the Newcastle phase in which I initiated it. It is currently under further development at CABIMER within Daniel Rico's Computational Epigenomics and Cell Identity group. Its continued development by that group, together with the public code and reusable supporting tools, gives the project a life beyond my own appointment and provides a concrete line of continuity for this contribution.
Public record:
Chromatinsight model, tutorial and test data,
companion R tools, and the
CABIMER research group where the work is being developed further.