PRMT8 is a membrane-associated, brain-enriched protein arginine methyltransferase that catalyzes asymmetric dimethylargination and monomethylargination of histone and non-histone substrates including histone H4, myelin basic protein, and the RNA-binding protein G3BP1 1. Structurally unique within the PRMT family, PRMT8 contains an N-terminal myristoylation motif that localizes it to the plasma membrane and cytoplasmic compartments 1. In human embryonic stem cells, PRMT8 maintains pluripotency through direct interaction with the PI3K regulatory subunit p85, activating the PI3K/AKT/SOX2 axis and enhancing mesodermal differentiation 2. At the synapse, PRMT8 regulates dendritic spine maturation by methylating G3BP1 and suppressing Rac1-PAK1 signaling to control actin dynamics; PRMT8 depletion results in synaptic dysfunction and abnormal dendritic morphology 3. PRMT8 also functions as a phospholipase, hydrolyzing phosphatidylcholine to regulate cerebellar development; knockout mice display motor dysfunction and abnormal Purkinje cell dendritic arborization 4. Clinically, high PRMT8 expression is detected in breast, ovarian, and cervical cancers, where it correlates with improved survival in breast and ovarian cancers but reduced survival in gastric cancer, positioning PRMT8 as a potential cancer biomarker 5.