Mathematical modeling of combinatorial regulation suggests that apparent positive regulation of targets by miRNA could be an artifact resulting from competition for mRNA

Schematic representation for the model. mRNA (m₁) associates and dissociates with miRNAs (μ₁ and μ₂) forming complexes c₁₁ and c₁₂. These complexes formed can be stoichiometrically degraded (rate constants d₁₁^c, d₁₂^c), selectively degraded (nonstoichiometric degradation, rate constants k₁₁^retm/μ and k₁₂^retm/μ), or can be associated with second miRNA to form combicomplex (c₁₁₂). The combicomplex formed can be stoichiometrically degraded. mRNA, complexes, and combicomplexes translate to form protein. The rate parameters are depicted in italics and species in bold. Unfilled arrows depict catalytic formation of protein from complexes and mRNA, dashed arrows represent nonstoichiometric degradation of one species from the complex returning the other species. (Ø) Sink/source.