Identifying Responsive Modules by Mathematical Programming: An Application to Budding Yeast Cell Cycle

Key Laboratory of Systems Biology, SIBS-Novo Nordisk Translational Research Centre for PreDiabetes, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
PLoS ONE (Impact Factor: 3.23). 07/2012; 7(7):e41854. DOI: 10.1371/journal.pone.0041854
Source: PubMed


High-throughput biological data offer an unprecedented opportunity to fully characterize biological processes. However, how to extract meaningful biological information from these datasets is a significant challenge. Recently, pathway-based analysis has gained much progress in identifying biomarkers for some phenotypes. Nevertheless, these so-called pathway-based methods are mainly individual-gene-based or molecule-complex-based analyses. In this paper, we developed a novel module-based method to reveal causal or dependent relations between network modules and biological phenotypes by integrating both gene expression data and protein-protein interaction network. Specifically, we first formulated the identification problem of the responsive modules underlying biological phenotypes as a mathematical programming model by exploiting phenotype difference, which can also be viewed as a multi-classification problem. Then, we applied it to study cell-cycle process of budding yeast from microarray data based on our biological experiments, and identified important phenotype- and transition-based responsive modules for different stages of cell-cycle process. The resulting responsive modules provide new insight into the regulation mechanisms of cell-cycle process from a network viewpoint. Moreover, the identification of transition modules provides a new way to study dynamical processes at a functional module level. In particular, we found that the dysfunction of a well-known module and two new modules may directly result in cell cycle arresting at S phase. In addition to our biological experiments, the identified responsive modules were also validated by two independent datasets on budding yeast cell cycle.

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    • "In a different approach to prior knowledge, gene-gene relationships (pathway-based or protein-protein interaction (PPI) networks) are used to improve classification accuracy [21], [22], [23], [24], [25], [30], consistency of biomarker discovery [26], [27] and targeted therapeutic strategies [28], [29]. The majority of these studies utilize gene expressions corresponding to sub-networks in PPI networks , for instance: mean or median of gene expression values in gene ontology network modules [21], probabilistic inference of pathway activity [24], and producing candidate sub-networks via a Markov clustering algorithm applied to high quality PPI networks [26], [31]. None of these methods incorporate the regulating mechanisms (activating or suppressing) into classification or featureselection . "
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