PI3KC2β

PI3KC2β is a class II phosphoinositide 3-kinase that regulates lipid signaling, vesicular trafficking, cytoskeletal organization, cell migration, and cell survival^[1]. Mechanistically, PI3KC2β links phosphoinositide metabolism to endosomal trafficking because PI3KC2β loss in human cerebral microvascular endothelial cells increases Rab11-dependent VE-cadherin recycling and stabilizes endothelial cell-cell junctions^[2]. In disease models, inactive PI3KC2β protects mice against vascular permeability, edema, cerebral infarction, and inflammatory response after ischemic stroke^[2]. PI3KC2β also limits endothelial mTORC1 signaling during angiogenic growth, and kinase-inactive PI3KC2β causes enlarged blood vessels through increased endothelial cell size rather than increased proliferation or migration^[3]. In MTM1-related myotubular myopathy models, PI3KC2β inhibition improves muscle function and survival, while selective kinase inactivation prevents muscle atrophy, weakness, histopathology, sarcomere defects, and triad disorganization in Mtm1-knockout mice^[4][5]. Compared with related isoforms, PI3KC2β differs from PI3KC2α because PI3KC2α deficiency increases vascular permeability, whereas PI3KC2β inactivation preserves vascular integrity after injury^[2]. For experimental applications, kinase-dead PI3KC2β models support target validation, but no specific PI3KC2β kinase inhibitor has been developed and published^[5].