R-loops are three-stranded DNA/RNA hybrids that form by the annealing of the mRNA transcript to its coding template while displacing the non-coding strand. While R-loop formation regulates physiological genomic and mitochondrial transcription and DNA damage response, imbalanced R-loop formation can be a threat to the genomic integrity of the cell. As such, R-loop formation is a double-edged sword in cancer progression, and perturbed R-loop homeostasis is observed across various malignancies. Here, we discuss the interplay between R-loops and tumor suppressors and oncogenes, with a focus on BRCA1/2 and ATR. R-loop imbalances contribute to cancer propagation and the development of chemotherapy drug resistance. We explore how R-loop formation can cause cancer cell death in response to chemotherapeutics and be used to circumvent drug resistance. As R-loop formation is tightly linked to mRNA transcription, their formation is unavoidable in cancer cells and can thus be explored in novel cancer therapeutics.

Multisystem proteinopathy (MSP) is a pleiotropic degenerative disorder which affects the nervous system, muscles, and bones. The identification of risk factors and their molecular contribution to MSP expands our understanding of disease mechanisms. Here, we describe a family with dominantly inherited MSP, in which a mutation in the serine/arginine repetitive matrix 2 gene (SRRM2) that co-segregates with disease, is identified. SRRM2 is essential for nuclear speckle formation and a constitutive member of the RNA splicing machinery. To investigate how the mutation in SRRM2 might contribute to MSP pathogenesis, we examined its effect on a model cell line, where the point mutation was introduced in the endogenous gene. Surprisingly, we found that the resulting single amino acid exchange led to the loss of protein-protein interaction between SRRM2 and the splicing factor ACIN1. Transcriptome studies further revealed widespread differential gene expression, which converged on the dysregulation of synapse-associated pathways. Together, our findings identify SRRM2 as a novel MSP risk factor and provide mechanistic insights into how its mutation can be linked to MSP pathology.