2012년도 봄학기 세미나

Abstract

Inositol is a naturally occurring glucose isomer and a key nutrient of the human diet. When levels of inositol are extremely low, disturbances such as diabetic changes, anxiety disorders, and hypercholesterolemia ensue. Inositol phosphates(IP) as signaling messengers mediate various physiological processes such as growth and apoptosis. IPMK(inositol polyphosphate multikinase) was first identified as Arg82, a transcriptional regulator in yeast. In mammals, IPMK generates inositol tetrakisphosphate(IP4) and IP5 and thus acts upstream of the IP6 kinase. IPMK is also a physiologically important PI3-kinase that forms PIP3 which activates Akt-dependent signaling pathways. IPMK, in a catalytically independent fashion, activates mammalian target of rapamycin(mTOR) in response to essential amino acids. In addition, IPMK regulates glucose signaling to AMP-activated kinase(AMPK) in a pathway whereby glucose activates phosphorylation of IPMK at tyrosine-174 enabling the enzyme to bind to AMPK and regulate its activation. These findings imply that IPMK participates in a network regulating growth factor– and nutrient-mediated signaling.