Dynamic changes in RNA m6A and 5 hmC influence gene expression programs during macrophage differentiation and polarisation.

RNA modifications are essential for the establishment of cellular identity. Although increasing evidence indicates that RNA modifications regulate the innate immune response, their role in monocyte-to-macrophage differentiation and polarisation is unclear. While m6A has been widely studied, other RNA modifications, including 5 hmC, remain poorly characterised. We profiled m6A and 5 hmC epitranscriptomes, transcriptomes, translatomes and proteomes of monocytes and macrophages at rest and pro- and anti-inflammatory states. Transcriptome-wide mapping of m6A and 5 hmC reveals enrichment of m6A and/or 5 hmC on specific categories of transcripts essential for macrophage differentiation. Our analyses indicate that m6A and 5 hmC modifications are present in transcripts with critical functions in pro- and anti-inflammatory macrophages. Notably, we also discover the co-occurrence of m6A and 5 hmC on alternatively-spliced isoforms and/or opposing ends of the untranslated regions (UTR) of mRNAs with key roles in macrophage biology. In specific examples, RNA 5 hmC controls the decay of transcripts independently of m6A. This study provides (i) a comprehensive dataset to interrogate the role of RNA modifications in a plastic system (ii) a resource for exploring different layers of gene expression regulation in the context of human monocyte-to-macrophage differentiation and polarisation, (iii) new insights into RNA modifications as central regulators of effector cells in innate immunity.

Overexpression of VIRMA confers vulnerability to breast cancers via the m6A-dependent regulation of unfolded protein response.

Virilizer-like m6A methyltransferase-associated protein (VIRMA) maintains the stability of the m6A writer complex. Although VIRMA is critical for RNA m6A deposition, the impact of aberrant VIRMA expression in human diseases remains unclear. We show that VIRMA is amplified and overexpressed in 15-20% of breast cancers. Of the two known VIRMA isoforms, the nuclear-enriched full-length but not the cytoplasmic-localised N-terminal VIRMA promotes m6A-dependent breast tumourigenesis in vitro and in vivo. Mechanistically, we reveal that VIRMA overexpression upregulates the m6A-modified long non-coding RNA, NEAT1, which contributes to breast cancer cell growth. We also show that VIRMA overexpression enriches m6A on transcripts that regulate the unfolded protein response (UPR) pathway but does not promote their translation to activate the UPR under optimal growth conditions. Under stressful conditions that are often present in tumour microenvironments, VIRMA-overexpressing cells display enhanced UPR and increased susceptibility to death. Our study identifies oncogenic VIRMA overexpression as a vulnerability that may be exploited for cancer therapy.

Cluster Sets to Prescribe Interval Resistance Training: A Potential Method to Optimise Resistance Training Safety, Feasibility and Efficacy in Cardiac Patients.

The integration of resistance training for cardiac patients leads to important health outcomes that are not optimally obtained with aerobic exercise; these include an increase in muscle mass, maintenance of bone mineral density, and improvements in muscular fitness parameters. Despite the proliferation of evidence supporting resistance exercise in recent decades, the implementation of resistance training is underutilised, and prescription is often sub-optimal in cardiac patients. This is frequently associated with safety concerns and inadequate methods of practical exercise prescription. This review discusses the potential application of cluster sets to prescribe interval resistance training in cardiac populations. The addition of planned, regular passive intra-set rest periods (cluster sets) in resistance training (i.e., interval resistance training) may be a practical solution for reducing the magnitude of haemodynamic responses observed with traditional resistance training. This interval resistance training approach may be a more suitable option for cardiac patients. Additionally, many cardiac patients present with impaired exercise tolerance; this model of interval resistance training may be a more suitable option to reduce fatigue, increase patient tolerance and enhance performance to these workloads. Practical strategies to implement interval resistance training for cardiac patients are also discussed. Preliminary evidence suggests that interval resistance training may lead to safer acute haemodynamic responses in cardiac patients. Future research is needed to determine the efficacy and feasibility of interval resistance training for health outcomes in this population.

Endoplasmic reticulum protein 5 attenuates platelet endoplasmic reticulum stress and secretion in a mouse model.

Extracellular protein disulfide isomerases (PDIs), including PDI, endoplasmic reticulum protein 57 (ERp57), ERp72, ERp46, and ERp5, are required for in vivo thrombus formation in mice. Platelets secrete PDIs upon activation, which regulate platelet aggregation. However, platelets secrete only ∼10% of their PDI content extracellularly. The intracellular role of PDIs in platelet function is unknown. Here, we aim to characterize the role of ERp5 (gene Pdia6) using platelet conditional knockout mice, platelet factor 4 (Pf4) Cre+/ERp5floxed (fl)/fl. Pf4Cre+/ERp5fl/fl mice developed mild macrothrombocytopenia. Platelets deficient in ERp5 showed marked dysregulation of their ER, indicated by a twofold upregulation of ER proteins, including PDI, ERp57, ERp72, ERp46, 78 kilodalton glucose-regulated protein (GRP78), and calreticulin. ERp5-deficient platelets showed an enhanced ER stress response to ex vivo and in vivo ER stress inducers, with enhanced phosphorylation of eukaryotic translation initiation factor 2A and inositol-requiring enzyme 1 (IRE1). ERp5 deficiency was associated with increased secretion of PDIs, an enhanced response to thromboxane A2 receptor activation, and increased thrombus formation in vivo. Our results support that ERp5 acts as a negative regulator of ER stress responses in platelets and highlight the importance of a disulfide isomerase in platelet ER homeostasis. The results also indicate a previously unanticipated role of platelet ER stress in platelet secretion and thrombosis. This may have important implications for the therapeutic applications of ER stress inhibitors in thrombosis.