SummaryTermination of RNA polymerase II (Pol II) transcription is a key step that is important for 3′ end formation of functional mRNA, mRNA release, and Pol II recycling. Even so, the underlying termination mechanism is not yet understood. Here, we demonstrate that the conserved and essential termination factor Seb1 is found on Pol II near the end of the RNA exit channel and the Rpb4/7 stalk. Furthermore, the Seb1 interaction surface with Pol II largely overlaps with that of the elongation factor Spt5. Notably, Seb1 co-transcriptional recruitment is dependent on Spt5 dephosphorylation by the conserved PP1 phosphatase Dis2, which also dephosphorylates threonine 4 within the Pol II heptad repeated C-terminal domain. We propose that Dis2 orchestrates the transition from elongation to termination phase during the transcription cycle by mediating elongation to termination factor exchange and dephosphorylation of Pol II C-terminal domain.

Termination of RNA polymerase II (Pol II) transcription is an important step in the transcription cycle, which involves the dislodgement of polymerase from DNA, leading to release of a functional transcript. Recent studies have identified the key players required for this process and showed that a common feature of these proteins is a conserved domain that interacts with the phosphorylated C-terminus of Pol II (CTD-interacting domain, CID). However, the mechanism by which transcription termination is achieved is not understood. Using genome-wide methods, here we show that the fission yeast CID-protein Seb1 is essential for termination of protein-coding and non-coding genes through interaction with S2-phosphorylated Pol II and nascent RNA. Furthermore, we present the crystal structures of the Seb1 CTD- and RNA-binding modules. Unexpectedly, the latter reveals an intertwined two-domain arrangement of a canonical RRM and second domain. These results provide important insights into the mechanism underlying eukaryotic transcription termination.

Recent evidence shows that the gut microbiota has an important role in gut-brain crosstalk and is linked to neuronal disorders. The aim of this study was to investigate the effects of intestinal Ruminococcus albus with probiotic potential on neuroprotection in oxidatively stressed SH-SY5Y neuroblastoma cells and animals. To investigate these effects, conditioned medium was prepared using Caco-2 cells cultured with heat-killed R. albus (CRA-CM). Caco-2 cells cultured with heat-killed R. albus showed increased BDNF expression and BDNF protein levels increased in CRA-CM. CRA-CM up-regulated the protein expression levels of SRF, C-fos and CDK2. In addition, CRA-CM protected SH-SY5Y cells from H2O2-induced cell death. CRA-CM significantly decreased the Bax/Bcl-2 ratio in oxidatively stressed SH-SY5Y cells. Animal experiments showed that oral administration of heat-killed R. albus for 15 days attenuated the oxidative stress induced by sodium arsenate. Treatment with heat-killed R. albus reduced the level of ROS, and the levels of SOD and GSH increased in oxidatively stressed brains. In conclusion, the secretome prepared from Caco-2 cells cultured with heat-killed R. albus might promote neuronal proliferation through the activation of cell proliferation-related proteins, and heat-killed R. albus protects neurons from oxidative damage by reducing ROS levels and increasing SOD and GSH levels.

The yeast Nrd1 interacts with the C-terminal domain (CTD) of RNA polymerase II (RNApII) through its CTD-interacting domain (CID) and also associates with the nuclear exosome, thereby acting as both a transcription termination and RNA processing factor. Previously, we found that the Nrd1 CID is required to recruit the nuclear exosome to the Nrd1 complex, but it was not clear which exosome subunits were contacted. Here, we show that two nuclear exosome cofactors, Mpp6 and Trf4, directly and competitively interact with the Nrd1 CID and differentially regulate the association of Nrd1 with two catalytic subunits of the exosome. Importantly, Mpp6 promotes the processing of Nrd1-terminated transcripts preferentially by Dis3, whereas Trf4 leads to Rrp6-dependent processing. This suggests that Mpp6 and Trf4 may play a role in choosing a particular RNA processing route for Nrd1-terminated transcripts within the exosome by guiding the transcripts to the appropriate exonuclease.The Nrd1-Nab3-Sen1 complex terminates transcription of small non-coding RNAs by RNApII 2 (1-4). Nrd1 and Nab3 are sequence-specific RNA binding proteins, and Sen1 helicase (senataxin in humans) has an ATPase activity that directly dissociates RNApII from the templates (5). Nrd1 also recognizes the serine 5-phosphorylated (Ser(P)-5) CTD of RNApII using its CID (6). Because the Ser(P)-5 CTD is prevalent in the early stage of transcription, the Nrd1 CID-RNApII CTD interaction has been suggested to dictate a regional specificity of Nrd1-Nab3-Sen1-dependent transcription termination (7). Indeed, Nrd1havingtheCIDofRtt103thatrecognizestheSerine2-phosphorylated CTD becomes capable of triggering RNApII termination at regions where Nrd1-Nab3 binding sites and serine 2-phosphorylated CTD are co-localized, satisfyingly confirming this model (8).The RNAs generated via Nrd1-Nab3-Sen1-dependent termination are trimmed or degraded by the exosome, mediated by Nrd1 complex interactions with this 3Ј-5Ј exonuclease (9). Intriguingly, swapping or deletion of the Nrd1 CID reduced the interaction between Nrd1 and the exosome (8), indicating that the Nrd1 CID also plays an important role in coupling termination and RNA processing by recruiting the exosome.The nuclear exosome consists of the core exosome and a nuclear-specific subunit Rrp6 (PM/Scl100 in humans) that functions in RNA 3Ј-end processing using 3Ј-5Ј exoribonuclease activity (10 -13). The core exosome is a catalytically inactive barrel-shaped complex composed of nine subunits (Exo-9: RNase pleckstrin homology-like proteins (Rrp41/42/43/45/46 and Mtr3) and S1/KH domain proteins (Rrp4/40 and Csl4)) as well as Dis3 (also known as Rrp44), which is a 3Ј-5Ј exo/endonuclease. Located at the bottom of Exo-9, Dis3 trims or degrades the RNA substrates passed through the central pore of . In contrast, Rrp6 sits on top of the Exo-9 S1/KH ring above the central channel, and the RNAs traverse the S1/KH ring and enter into the active site of Rrp6 for degradation (15,16).The TRAMP (Trf4/5-Air1/2-Mtr4 polyadenylation) complex is ...

Background: Distinct termination pathways for yeast RNA polymerase II (RNApII) employ proteins (Nrd1 and Rtt103) recognizing different phospho-forms of the RNApII C-terminal domain (CTD). Results: Alteration of CTD-binding specificity of Nrd1 significantly affects RNApII termination. Conclusion: Differential interaction between RNApII CTD and termination factors is crucial in choosing a termination pathway. Significance: CTD-interacting domain of Nrd1 couples termination and RNA processing by the nuclear exosome.

It is important to accurately regulate the expression of genes involved in development and environmental response. In the fission yeast Schizosaccharomyces pombe, meiotic genes are tightly repressed during vegetative growth. Despite being embedded in heterochromatin these genes are transcribed and believed to be repressed primarily at the level of RNA. However, the mechanism of facultative heterochromatin formation and the interplay with transcription regulation is not understood. We show genome-wide that HDAC-dependent histone deacetylation is a major determinant in transcriptional silencing of facultative heterochromatin domains. Indeed, mutation of class I/II HDACs leads to increased transcription of meiotic genes and accumulation of their mRNAs. Mechanistic dissection of the pho1 gene where, in response to phosphate, transient facultative heterochromatin is established by overlapping lncRNA transcription shows that the Clr3 HDAC contributes to silencing independently of SHREC, but in an lncRNA-dependent manner. We propose that HDACs promote facultative heterochromatin by establishing alternative transcriptional silencing.

H3K14ac; HDAC; Clr3; Clr4, RNA polymerase II 12 not peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/219535 doi: bioRxiv preprint first posted online Nov. 14, 2017;

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