title: Robustness and modular design of the Drosophila segment polarity network.
abstract: Biomolecular networks have to perform their functions robustly. A robust function may have preferences in the topological structures of the underlying network. We carried out an exhaustive computational analysis on network topologies in relation to a patterning function in Drosophila embryogenesis. We found that whereas the vast majority of topologies can either not perform the required function or only do so very fragilely, a small fraction of topologies emerges as particularly robust for the function. The topology adopted by Drosophila, that of the segment polarity network, is a top ranking one among all topologies with no direct autoregulation. Furthermore, we found that all robust topologies are modular-each being a combination of three kinds of modules. These modules can be traced back to three subfunctions of the patterning function, and their combinations provide a combinatorial variability for the robust topologies. Our results suggest that the requirement of functional robustness drastically reduces the choices of viable topology to a limited set of modular combinations among which nature optimizes its choice under evolutionary and other biological constraints.
authors.affiliation: Center for Theoretical Biology, Peking University, Beijing, China.
authors.forename: Wenzhe
authors.initials: W
authors.lastname: Ma
authors.forename: Luhua
authors.initials: L
authors.lastname: Lai
authors.forename: Qi
authors.initials: Q
authors.lastname: Ouyang
authors.forename: Chao
authors.initials: C
authors.lastname: Tang
mesh_terms: D000818:Animals; D005075:Biological Evolution; D019521:Body Patterning; D003198:Computer Simulation; D029721:Drosophila Proteins / Q000502:physiology; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000502:physiology*; D025461:Feedback, Physiological; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D008954:Models, Biological; D015398:Signal Transduction; D049490:Systems Biology / Q000379:methods*; D014157:Transcription Factors
chemical_list: D029721:Drosophila Proteins; D014157:Transcription Factors