Biology subjects

Gwynne, M.

Publications and source records attributed to Gwynne, M..

3 recordsLinked to original sources

bioRxiv2025

PRMT activity promotes global 3' UTR shortening in proliferating cells

Protein methyltransferase (PRMT)-catalysed arginine methylation is a widespread post-translational modification that regulates numerous RNA-binding proteins and frequently becomes dysregulated in cancer. While PRMT inhibitors have shown promise as an anti-cancer strategy, greater understanding of the downstream pathways linking arginine methylation to tumour-promoting phenotypes is needed to improve patient stratification and develop more effective therapeutic approaches. Here, we reveal arginine methylation as a critical regulator of alternative polyadenylation (APA) patterns that are fundamental to tumour progression. 3' RNA-sequencing assays uncover a rapid and global shift toward longer 3' UTR isoforms upon dual (symmetric and asymmetric) methylation (DMAi), impacting a broad range of cellular proliferation and signalling genes. Arginine methylation is required for sustaining proximal poly(A) site usage under high proliferative demand, as DMAi treatment blocks use of such sites in activated T cells, various cancer cell lines and patient-derived lung organoids. DMAi also counteracts the 3' UTR shortening caused by reduced CFIM25 expression, which normally promotes oncogenic isoforms. DMAi treatment affects APA in many of the same mRNAs as impaired cleavage and polyadenylation activity, and these mRNAs contain characteristic signatures such as high GC-content and long 3 UTRs. This systematic impact of PRMT activity on APA regulation broadens the potential utility of PRMT inhibitors as therapeutic agents for both cancer and immune-related diseases.

molecular biology↗

bioRxiv2024

A co-transcriptional mechanism for tightly controlling RNA homeostasis in yeast

Transcription termination by the Nrd1-Nab3-Sen1 (NNS) complex is key in repressing pervasive transcription in Saccharomyces cerevisiae. Counterintuitively, during starvation, multiple mRNAs that are upregulated are also increasingly bound and prematurely terminated and degraded via NNS. Here we demonstrate that this NNS-mediated attenuation is important for controlling the expression and protein concentration of an evolutionarily conserved mitochondrial transporter, Pic2. Strikingly, we find that even a modest increase in Pic2 protein levels caused by defective NNS regulation has major phenotypical consequences, increasing cell volume and intracellular stress, prolonging cell cycle and decreasing growth rate. Disrupting Nab3 binding to PIC2 globally redistributed Nrd1 binding, changing the levels of other NNS-regulated transcripts. We propose that imbalances in the availability of the subunits constituting the NNS complex underlie the cell volume and cycle anomalies. Collectively our results illustrate that even subtle changes in how RNA-binding proteins interact with a single RNA substrate can cause global defects and they emphasise the crucial role of the NNS complex in preserving microbial fitness during stress. HighlightsO_LINNS regulates the expression and protein concentration of a stress-response protein-coding gene (PIC2), improving cell fitness and adaptability to environmental challenges. C_LIO_LICreating an imbalance in RNA binding of Nab3 and Nrd1 for PIC2 mRNA disturbs the homeostasis of co-regulated transcripts. C_LIO_LIEven a modest defect in NNS regulation of PIC2 elicits severe defects in cell growth, increases cell size and intracellular stress, and prolongs the cell cycle. C_LI

molecular biology↗

bioRxiv2024

Malat1 regulates female Th2 cell cytokine expression through controlling early differentiation and response to IL2

Identifying cell intrinsic regulators of immune sexual dimorphism is critical for treatment of several immunopathologies. We show that Malat1 is required for appropriate cytokine expression in female but not male Th2 cells. Malat1 deficiency impairs in vitro Th2 differentiation of naive CD4+ T cells from female mice, characterised by transcriptome-wide effects and suppression of cytokine expression, particularly IL10. Upon IL10R blockade a pronounced effect is also seen on IL4 and IL13. Mechanistically, naive CD4+ T cells from Malat1-/- female mice demonstrate altered early activation kinetics and impaired early differentiation gene expression, including up-regulation of an interferon stimulated gene (ISG) module. This is followed by suppression of IL2R and IL2R{gamma} expression and IL2-mediated differentiation. Mimicking the effect of Malat1 loss by maintaining early ISG expression in WT cells with IFN{beta} treatment partially phenocopies the effects of Malat1 deficiency. A subset of the effects of Malat1 loss in female cells is also observed in male cells. However, this does not affect endpoint Th2 differentiation. Male CD4+ T cells demonstrate stronger early activation, higher ISG expression during early differentiation, maintenance of IL2R expression independently of Malat1, and lower sensitivity to exogenous IL2 during late differentiation compared to female cells. In vivo, female, but not male, Malat1-/- mice demonstrate altered Th2 cytokine expression characterised by a reduction in IL10+ Th2 cells in both lung and spleen following priming and challenge with Schistosoma mansoni eggs, a model of lung type 2 inflammation. Overall, these findings reveal Malat1 as a novel determinant of immune sexual dimorphism.

immunology↗