Abstract: Embodiments of the disclosure concern the use of expression constructs in which at least one polyA signal is embedded upstream of an expressible transcript, such as within a 5? UTR for the transcript, for example. In certain embodiments, the polyA signal is comprised within a ligand-binding aptamer, and the binding of the ligand to the aptamer, or lack thereof, dictates the outcome for the expressible transcript. In specific embodiments, absence of the ligand causes the expressed transcript having a polyA in its 5? UTR to be expressed but then degraded, whereas presence of the ligand causes inhibition of degradation upon expression of the expressible transcript. More than one ligand-binding aptamer may be present on the same expression construct.

Abstract: Embodiments of the disclosure concern the use of expression constructs in which at least one polyA signal is embedded upstream of an expressible transcript, such as within a 5? UTR for the transcript, for example. In certain embodiments, the polyA signal is comprised within a ligand-binding aptamer, and the binding of the ligand to the aptamer, or lack thereof, dictates the outcome for the expressible transcript. In specific embodiments, absence of the ligand causes the expressed transcript having a polyA in its 5? UTR to be expressed but then degraded, whereas presence of the ligand causes inhibition of degradation upon expression of the expressible transcript. More than one ligand-binding aptamer may be present on the same expression construct.