Meta-regulation Network motifs. (A) The meta-regulation network model integrates TFs, miRNAs and target genes with their regulations. This model allows describing two biologically relevant systems (FBL and FFL) that can be modelled as "network motifs". (B) The FBL "network motif" model describes a reciprocal regulation between a TF and a miRNA. (C, D, E) The FFL "network motif" model that includes additional target genes, can be illustrated as three distinct models: the FFL-miRNA model describes the regulation of a TF and a targeted gene by the same miRNA (C), the FFL-TF model describes the regulation of a miRNA and a targeted gene by the same the TF (D) and the FFL-indirect model integrates an additional TF in the FFL-TF (E).