Poorwa Awasthi

Key words Phosphoinositide PITP PI4KIIα p53 linked PIPs PI4,5P2 PI3,4,5P3 nucleus cell stress Akt Introduction Phosphoinositide (PIPn) lipids are synthesized from phosphatidylinositol (PI) in membranes by PIP-metabolizing enzymes, including kinases and phosphatases, to produce a second messenger network comprised of seven distinct isomers that play key roles in many cellular pathways1.

Key words Phosphoinositide phosphatidylinositol transfer protein PI 4-kinase PIPn-linked proteins p53 PI4,5P2 PI3,4,5P3 nucleus cell stress Akt Introduction Phosphoinositide (PIPn) lipid second messengers are synthesized in membranes from phosphatidylinositol (PI) by PIP kinases and phosphatases to regulate metabolism, membrane trafficking, motility, cell growth and death1-5.

Abstract Phosphoinositide (PIPn) messengers are present in non-membranous regions of nuclei where they are assembled into a phosphatidylinositol (PI) 3-kinase (PI3K)/Akt pathway that is distinct from the cytosolic membrane-localized pathway. In the nuclear pathway, PI kinases/phosphatases bind the p53 tumor suppressor protein (wild-type and mutant) to generate p53-PIPn complexes (p53-PIPn signalosome) that activate Akt by a PI3,4,5P3-dependent mechanism in non-membranous regions of the nucleus.