Nuclear pre-mRNA degradation contributes to increased and decreased gene expression during nutrition shift.
Diagram depicting the response of Pol II and the nuclear surveillance factors NNS and TRAMP to glucose starvation. During glucose replete conditions, NNS and TRAMP are mainly restricted to promoter-proximal sites, likely targeting the products of abortive transcription. Following glucose withdrawal, NNS and TRAMP bind at sites further downstream, resulting in transcript oligoadenylation and degradation by the nuclear exosome complex (shown as pacman). Many stress response genes are transcriptionally induced following nutrient downshift due to loss of upstream transcripts that are strong targets for NNS mediated termination and degradation.