Figure 1.

Pre-mRNA and mRNA response profiles for stimulus-induced production and degradation changes. Different time-dependent production rates (green) and degradation coefficients (gold) are shown in the left column. Resulting pre-mRNA (red) and mRNA (blue) profiles, obtained by numerically solving Equations (4) and (5), are presented for mRNAs with initial half-lives of 30 and 120 min in the middle and right columns, respectively. All strategies yield a 5-fold change in the steady-state mRNA level, pre-mRNA profiles closely mimic production, while mRNA FC profiles are delayed and may be qualitatively different. (A) Five-fold step increase of production rate at time t=0. A rapid increase of pre-mRNA levels is followed by slower mRNA response. Dashed black line indicates the rise time to half of the aimed level, determined by the mRNA half-life. (B) Signal-induced 5-fold step decrease of degradation rate. Pre-mRNA levels reflect unchanged production; mRNA accumulates now more slowly compared with (A). (C) Signal-induced transient overshoot in production rate accelerates mRNA induction, particularly for mRNAs with long initial half-lives. (D) Five-fold step decrease in production rate at t=0. (E) Degradation driven downregulation: response time is shorter due to reduction of the mRNA half-life. (F) A transient overshoot in degradation accelerates response time of downregulated genes.