title: Modeling gene regulatory network motifs using Statecharts.
abstract: BACKGROUND
  Gene regulatory networks are widely used by biologists to describe the interactions among genes, proteins and other components at the intra-cellular level. Recently, a great effort has been devoted to give gene regulatory networks a formal semantics based on existing computational frameworks.For this purpose, we consider Statecharts, which are a modular, hierarchical and executable formal model widely used to represent software systems. We use Statecharts for modeling small and recurring patterns of interactions in gene regulatory networks, called motifs.
  
  
  RESULTS
  We present an improved method for modeling gene regulatory network motifs using Statecharts and we describe the successful modeling of several motifs, including those which could not be modeled or whose models could not be distinguished using the method of a previous proposal.We model motifs in an easy and intuitive way by taking advantage of the visual features of Statecharts. Our modeling approach is able to simulate some interesting temporal properties of gene regulatory network motifs: the delay in the activation and the deactivation of the "output" gene in the coherent type-1 feedforward loop, the pulse in the incoherent type-1 feedforward loop, the bistability nature of double positive and double negative feedback loops, the oscillatory behavior of the negative feedback loop, and the "lock-in" effect of positive autoregulation.
  
  
  CONCLUSIONS
  We present a Statecharts-based approach for the modeling of gene regulatory network motifs in biological systems. The basic motifs used to build more complex networks (that is, simple regulation, reciprocal regulation, feedback loop, feedforward loop, and autoregulation) can be faithfully described and their temporal dynamics can be analyzed.
authors.affiliation: Department of Biology, University of Rome Tor Vergata, Rome I-00133, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Fioravanti
authors.forename: Manuela
authors.initials: M
authors.lastname: Helmer-Citterich
authors.forename: Enrico
authors.initials: E
authors.lastname: Nardelli
mesh_terms: D004926:Escherichia coli / Q000235:genetics; D053263:Gene Regulatory Networks; D008954:Models, Biological; D012984:Software; D049490:Systems Biology / Q000379:methods*