MicroRNAs are able to modulate gene expression at the posttranscriptional level and play an essential role in various biological processes. In this paper, we establish a general model of an miRNA-mediated gene regulatory network motif with extracellular stimulus. Dynamical properties of the regulatory motif without stimulus focus on diverse codimension-1 and codimension-2 bifurcation analyses of two important feedback strengths as the parameters. Under varying levels of stimulus, we further consider stochastic dynamics controlled by crucial behaviors of monostability, bistability, excitability and oscillation in four typical regions on different two-parameter bifurcation diagrams. Furthermore, we apply potential landscapes to characterize global dynamics and stability behind physical properties of the stochastic behaviors. More essentially, our model can qualitatively simulate experimental findings of long-term memory formation in Aplysia.

MicroRNA能够在转录后水平调节基因表达，并在各种生物学过程中发挥重要作用。在本文中，我们建立了一个miRNA介导的具有细胞外刺激的基因调控网络基序的通用模型。在没有刺激的情况下，调节基元的动力学特性集中于对两个重要反馈强度作为参数的codimension-1和codimension-2分叉分析。在不同级别的刺激下，我们进一步考虑了随机动力学，这些动力学是由在不同两参数分叉图上的四个典型区域中的单稳态，双稳态，兴奋性和振动的关键行为控制的。此外，我们应用潜在的景观来表征随机行为的物理属性背后的全球动态和稳定性。更重要的是，海兔。