A mass spectrometric method for in-depth profiling phosphoinositide regioisomers and their disease-associated regulation. Homo sapiens

Phosphoinositides are a family of membrane lipids essential for many biological and pathological processes. Due to the existence of multiple phosphoinositide regioisomers and their low intracellular concentrations, profiling these lipids and linking a specific acyl variant to a change in biological state have been difficult. A method allowing the comprehensive analysis of phosphoinositides' phosphorylation status and acyl chain identity has long been awaited. Here, we report a new technique for phosphoinositide regioisomer measurement that employs chiral column chromatography plus mass spectrometry (PRMC-MS). Using this method, we revealed a severe skewing in acyl chains in phosphoinositides in Pten-deficient prostate cancer tissues, extracellular mobilization of phosphoinositides upon expression of oncogenic PIK3CA, and a unique profile for exosomal phosphoinositides. Thus, our novel approach has revealed previously hidden dynamics of phosphoinositide acyl variants in intracellular and extracellular milieus.