Protein arginine methyltransferases as regulators of phase separation: implications in cancer and neurodegenerative diseases.

Protein arginine methyltransferases (PRMTs) catalyze arginine methylation, a key post-translational modification (PTM) regulating chromatin organization, RNA metabolism, and signaling. Recent studies reveal that PRMT-mediated methylation also modulates liquid-liquid phase separation (LLPS), which organizes membraneless condensates controlling transcription, stress response, and genome stability. Dysregulated PRMT activity disrupts condensate dynamics, contributing to cancer and neurodegenerative diseases. In cancer, PRMT1, PRMT5, and PRMT6 promote tumor progression via methylation-dependent condensates that enhance oncogenic transcription and stress resistance. In the nervous system, PRMT1, PRMT4, PRMT5, PRMT6, and PRMT8 regulate LLPS of proteins, linking aberrant methylation to ALS and Huntington's disease. This review highlights PRMTs as key modulators of phase separation and potential therapeutic targets in both oncology and neurodegeneration.