PNISR (PNN interacting serine and arginine rich protein) is an RNA-binding protein that functions as a splicing factor involved in RNA processing and regulation. The protein localizes to nuclear speckles and contains serine/arginine-rich domains characteristic of splicing regulators 1. PNISR interacts with circular RNAs, particularly circ_0001400, which is induced by viral infections including KSHV, suggesting a role in host-pathogen interactions and viral latency maintenance 1. The gene shows altered expression in various disease contexts, being upregulated in pulmonary arterial hypertension where it serves as a potential diagnostic biomarker with 72.4% AUC in ROC analysis 2. PNISR is also associated with Alzheimer's disease pathogenesis, showing correlation with lactate metabolism-related processes and exhibiting diagnostic potential (AUC: 0.724) 3. Additionally, PNISR expression is increased in the nucleus accumbens of highly impulsive rats, suggesting involvement in behavioral regulation and potentially psychiatric disorders 4. The protein has been identified in various molecular networks related to cancer, metabolic pathways, and neurodegenerative processes, indicating its broad regulatory functions in cellular metabolism and disease states 235.