A multiscale model of epigenetic heterogeneity-driven cell fate decision-making
Fig 2
Schematic reprentation of the ER-GRN model and its multiscale reduction.
(a): Gene regulatory network (GRN) of two self-activating, mutually-inhibitory genes with epigenetic regulation (ER). In the GRN model, the gene product (single circle, denoted by Xi in S2 Table) is its own transcription factor which, upon dimerisation (two joint circles), binds the promoter region of the gene thus triggering gene transcription. The transition rates corresponding to this GRN are given in S2 Table. For simplicity, we use an effective model in which the formation of the dimer and binding to the promoter region is taken into account in a single reaction, and the resulting number of promoter sites bound by two transcription factors is denoted by Xij (see S2 Table). Furthermore, depending on whether the epigenetic state is open (i.e. predominantly acetylated (A)) or closed (i.e. predominantly methylated (M)) the promoter region of the gene is accessible or inaccessible to the transcription factor, respectively. (b): Schematic representation of the time separation structure of the multiscale method developed to simulate the ER-GRN system. See text and S1 Text for more details.