Gene-specific RNA homeostasis revealed by perturbation of the NuA4/Tip60 acetyltransferase complex

Abstract

SummaryTranscript buffering entails the reciprocal modulation of mRNA synthesis and degradation rates, ensuring a constant RNA concentration amidst changes in cellular conditions. While an increasing body of research supports a global, non-sequence-specific linkage between mRNA synthesis and degradation, the underlying mechanisms remain elusive. To explore this, we investigated alterations in RNA metabolism following the acute depletion of TIP60/KAT5, the transcriptional coactivator and acetyltransferase subunit of the NuA4 complex, in mouse embryonic stem cells. By combining RNA sequencing of nuclear, cytoplasmic, and newly synthesised transcript fractions with biophysical modelling, we show that TIP60 activates transcription of numerous genes, with substantially fewer genes undergoing transcriptional repression. Surprisingly, specific RNA species’ transcription changes triggered by TIP60 depletion were counterbalanced by compensatory adjustments in RNA export and/or stability within the nucleus and in RNA stability within the cytoplasm. These discoveries imply that transcript buffering operates on a gene-specific level and suggest that cells continually monitor RNA molecule counts in nuclear and cytoplasmic compartments to maintain cellular homeostasis.