Oncogene-induced senescence (OIS) can occur in response to oncogenic insults and is considered an important tumour suppressor mechanism. Here we identify the lncRNA MIR31HG as upregulated in OIS and find that knockdown of MIR31HG promotes a strong p16 INK4A -dependent senescence phenotype. Under normal conditions, MIR31HG is found in both nucleus and cytoplasm, but following B-RAF expression MIR31HG is located mainly in the cytoplasm. We show that MIR31HG interacts with both INK4A and MIR31HG genomic regions and with Polycomb group (PcG) proteins, and that MIR31HG is required for PcG-mediated repression of the INK4A locus. We further identify a functional enhancer, located between MIR31HG and INK4A, which becomes activated during OIS and interacts with the MIR31HG promoter. Data from melanoma patients show a negative correlation between MIR31HG and p16 INK4A expression levels, suggesting a role for this transcript in cancer. Hence, our data provide a new lncRNA-mediated regulatory mechanism for the tumour suppressor p16 INK4A .

Introduction: We evaluate the impact of COVID-epidemic in colorectal cancer (CRC) diagnosis during Spain's state of emergency. Methods: We compared newly diagnosed patients with patients diagnosed in the same period of 2019. Results: A new diagnosis of CRC decreased 48% with a higher rate of patients diagnosed in the emergency setting (12.1% vs. 3.6%; p = .048) and a lower rate diagnosed in the screening program (5.2% vs. 33.3%; p = .000). Conclusions: Fewer patients have been diagnosed with CRC, with a higher rate of patients diagnosed in an emergency setting.

Complex functional coupling exists between transcriptional elongation and pre-mRNA alternative splicing. Pausing sites and changes in the rate of transcription by RNA polymerase II (RNAPII) may therefore have fundamental impacts in the regulation of alternative splicing. Here, we show that the elongation and splicing-related factor TCERG1 regulates alternative splicing of the apoptosis gene Bcl-x in a promoter-dependent manner. TCERG1 promotes the splicing of the short isoform of Bcl-x (Bcl-x s ) through the SB1 regulatory element located in the first half of exon 2. Consistent with these results, we show that TCERG1 associates with the Bcl-x pre-mRNA. A transcription profile analysis revealed that the RNA sequences required for the effect of TCERG1 on Bcl-x alternative splicing coincide with a putative polymerase pause site. Furthermore, TCERG1 modifies the impact of a slow polymerase on Bcl-x alternative splicing. In support of a role for an elongation mechanism in the transcriptional control of Bcl-x alternative splicing, we found that TCERG1 modifies the amount of pre-mRNAs generated at distal regions of the endogenous Bcl-x. Most importantly, TCERG1 affects the rate of RNAPII transcription of endogenous human Bcl-x. We propose that TCERG1 modulates the elongation rate of RNAPII to relieve pausing, thereby activating the proapoptotic Bcl-x S 5= splice site.T he expression of protein-coding genes in eukaryotes is a highly orchestrated process that involves multiple coordinated events. Genomic DNA must be transcribed into precursor mRNAs (pre-mRNA) by RNA polymerase II (RNAPII) and processed through subsequent steps to yield a mature mRNA that is exported from the nucleus to the cytoplasm and used by the translational machinery. The pre-mRNA undergoes several processing steps, including capping, splicing, and cleavage/polyadenylation, which appear to be precisely coordinated with nascent transcript formation (41,44,49). Of these RNA processing mechanisms, alternative splicing occurs as a widespread means to achieve proteomic diversity. Results of deep sequencing-based expression analyses estimate that more than 90% of multiexon human genes undergo alternative splicing (50, 66). The misregulation of alternative splicing underlies multiple diseases, including neurological disorders and cancer (5,19,32,67).Although transcription and alternative splicing can occur independently, both processes are physically and functionally interconnected (44, 49), and this coupling and coordination may be important for the regulation of gene expression. To date, two models have been proposed to explain the link between transcription and splicing. In the recruitment model, the unique carboxylterminal domain (CTD) of RNAPII functions as a "landing pad" for factors involved in pre-mRNA splicing in a manner that is dependent on the phosphorylation of RNAPII and the resulting functional state of the transcriptional complex (4,7,28,38,40,42,43,71). In the kinetic model, an alternative but not exclusive model, the transcript elongation...

The first stable complex formed during the assembly of spliceosomes onto pre-mRNA substrates in mammals includes U1 snRNP, which recognizes the 5 ′ splice site, and the splicing factors SF1 and U2AF, which bind the branch point sequence, polypyrimidine tract, and 3 ′ splice site. The 5 ′ and 3 ′ splice site complexes are thought to be joined together by proteinprotein interactions mediated by factors that ensure the fidelity of the initial splice site recognition. In this study, we identified and characterized PRPF40B, a putative mammalian ortholog of the U1 snRNP-associated yeast splicing factor Prp40. PRPF40B is highly enriched in speckles with a behavior similar to splicing factors. We demonstrated that PRPF40B interacts directly with SF1 and associates with U2AF 65 . Accordingly, PRPF40B colocalizes with these splicing factors in the cell nucleus. Splicing assays with reporter minigenes revealed that PRPF40B modulates alternative splice site selection. In the case of Fas regulation of alternative splicing, weak 5 ′ and 3 ′ splice sites and exonic sequences are required for PRPF40B function. Placing our data in a functional context, we also show that PRPF40B depletion increased Fas/CD95 receptor number and cell apoptosis, which suggests the ability of PRPF40B to alter the alternative splicing of key apoptotic genes to regulate cell survival.

The tightly regulated process of precursor messenger RNA (pre-mRNA) alternative splicing is a key mechanism to increase the number and complexity of proteins encoded by the genome. Evidence gathered in recent years has established that transcription and splicing are physically and functionally coupled and that this coupling may be an essential aspect of the regulation of splicing and alternative splicing. Recent advances in our understanding of transcription and of splicing regulation have uncovered the multiple interactions between components from both types of machinery. These interactions help to explain the functional coupling of RNAPII transcription and pre-mRNA alternative splicing for efficient and regulated gene expression at the molecular level. Recent technological advances, in addition to novel cell and molecular biology approaches, have led to the development of new tools for addressing mechanistic questions to achieve an integrated and global understanding of the functional coupling of RNAPII transcription and pre-mRNA alternative splicing. Here, we review major milestones and insights into RNA polymerase II transcription and pre-mRNA alternative splicing as well as new concepts and challenges that have arisen from multiple genome-wide approaches and analyses at the single-cell resolution.

Cellular senescence is a complex stress response that leads to an irreversible state of cell growth arrest. Senescence may be induced by various stimuli such as telomere shortening, DNA damage or oncogenic insult, among others. Senescent cells are metabolically highly active, producing a wealth of cytokines and chemokines that, depending on the context, may have a beneficial or deleterious effect on the organism. Senescence is considered a tightly regulated stress response that is largely governed by the p53/p21 and p16/Rb pathways. Many molecules have been identified as regulators of these two networks, such as transcription factors, chromatin modifiers and non‐coding RNAs. The expression level of several long non‐coding RNAs is affected during different types of senescence; however, which of these are important for the biological function remains poorly understood. Here we review our current knowledge of the mechanistic roles of lncRNAs affecting the main senescence pathways, and discuss the importance of identifying new regulators.

Modification of proteins by small ubiquitin-like modifier (SUMO) is emerging as an important control of transcription and RNA processing. The human factor TCERG1 (also known as CA150) participates in transcriptional elongation and alternative splicing of pre-mRNAs. Here, we report that SUMO family proteins modify TCERG1. Furthermore, TCERG1 binds to the E2 SUMO-conjugating enzyme Ubc9. Two lysines (Lys-503 and Lys-608) of TCERG1 are the major sumoylation sites. Sumoylation does not affect localization of TCERG1 to the splicing factor-rich nuclear speckles or the alternative splicing function of TCERG1. However, mutation of the SUMO acceptor lysine residues enhanced TCERG1 transcriptional activity, indicating that SUMO modification negatively regulates TCERG1 transcriptional activity. These results reveal a regulatory role for sumoylation in controlling the activity of a transcription factor that modulates RNA polymerase II elongation and mRNA alternative processing, which are discriminated differently by this post-translational modification.Splicing and transcriptional elongation are physically and functionally interconnected processes (1, 2). Although both processes can occur autonomously, their coupling and coordination may be important for regulation of gene expression. Coupling of these two processes may influence splicing and alternative splicing regulation. Indeed, promoter composition, transcriptional elongation efficiency, chromatin environment, and recruitment of specific coregulators to the transcriptional complex have been shown to affect alternative splicing decisions in a number of experimental systems (3-6). Yet the molecular mechanisms at work are not understood. The unique carboxyl-terminal domain (CTD) 4 of the large subunit of RNA-PII seems to play a central role in the coupling of splicing, as well as other RNA processing functions, to transcription (7, 8).To provide a framework, we consider two models as follows: the recruiting and kinetic models, which are not mutually exclusive. In the "recruiting model," the CTD functions as a "landing pad" for specific subsets of RNA processing factors in a manner dependent on its phosphorylation pattern and therefore on the functional state of the transcription complex (9). A number of independent research lines have suggested that RNA splicing factors can interact with RNAPII molecules that are hyperphosphorylated on their CTD (10 -14), although these associations might be highly dynamic and transient in vivo. The integrity of the RNAPII CTD has also been shown to influence the recruitment of splicing factors to active transcription sites in the nucleus (15). The "kinetic model" (1) proposes that the rate of elongation of the nascent transcript affects specific alternative splicing decisions by modulating the probability of simultaneous presentation of competing splicing sites. Thus, modulation of transcription elongation efficiency at specific, alternatively spliced regions of genes might constitute a mechanism to regulate splicing decisions (5). Sev...

Oncogene-induced senescence provides a barrier against malignant transformation. However, it can also promote cancer through the secretion of a plethora of factors released by senescent cells, called the senescence associated secretory phenotype (SASP). We have previously shown that in proliferating cells, nuclear lncRNA MIR31HG inhibits p16/CDKN2A expression through interaction with polycomb repressor complexes and that during BRAF-induced senescence, MIR31HG is overexpressed and translocates to the cytoplasm. Here, we show that MIR31HG regulates the expression and secretion of a subset of SASP components during BRAF-induced senescence. The SASP secreted from senescent cells depleted for MIR31HG fails to induce paracrine invasion without affecting the growth inhibitory effect. Mechanistically, MIR31HG interacts with YBX1 facilitating its phosphorylation at serine 102 (p-YBX1S102) by the kinase RSK. p-YBX1S102 induces IL1A translation which activates the transcription of the other SASP mRNAs. Our results suggest a dual role for MIR31HG in senescence depending on its localization and points to the lncRNA as a potential therapeutic target in the treatment of senescence-related pathologies.