TRiC/CCT Chaperonin Regulates RNA Polymerase II in the Nucleus [RNA-seq]
The molecular chaperonin TRiC/CCT is a large hetero-oligomeric structure that serves an essential role in eukaryotic cells by minimally supporting protein homeostasis including the folding of nascent polypeptides and the assembly/disassembly of protein complexes. TRiC/CCT is typically considered a strict cytosolic machine. Here, we investigated the influence of TRiC/CCT on nuclear features including epigenetic marks, chromatin accessibility, and transcription. Despite being linked to several chromatin modifiers, our work indicates TRiC/CCT does not have a sustained role with these factors. TRiC/CCT did actively contribute to transcription. Inactivation of TRiC/CCT resulted in a significant increase in the production of RNA leading to an accumulation of noncoding transcripts. Our data support a direct role for TRiC/CCT with RNA polymerase II as the chaperonin modulated nascent RNA production both in vivo and in vitro. Overall, our studies reveal a new avenue by which TRiC/CCT contributes to cell homeostasis by regulating the activity of nuclear RNA polymerase II. Overall design: To assess the influence of the CCT chaperonin on nuclear events, we examined steady-state RNA transcripts in the presence and absence of active CCT. To inactivate CCT, we used the temperature sensitive strain cct1-2. WT and cct1-2 and an established temperature regime of 4 h at 37°C, which prompts cessation of cell growth that is reversible following a return to a permissive temperature (Ursic et al. 1994). In brief, exponentially growing parental and cct1-2 yeast were shifted to 37°C for 4 h. RNA was isolated and subjected to NGS. RNA-Seq analysis was performed: Differential gene expression was done by comparing WT and cct1-2; regions with cryptic transcription events were analyzed.