Showing papers by "Chang Hwa Jung published in 2009"
TL;DR: It is identified that mTOR phosphorylates a mammalian homologue of Atg13 and the mammalian Atg1 homologues ULK1 and ULK2, which demonstrate that the ULK-Atg13-FIP200 complexes are direct targets of mTOR and important regulators of autophagy in response to mTOR signaling.
Abstract: Autophagy, the starvation-induced degradation of bulky cytosolic components, is up-regulated in mammalian cells when nutrient supplies are limited. Although mammalian target of rapamycin (mTOR) is known as the key regulator of autophagy induction, the mechanism by which mTOR regulates autophagy has remained elusive. Here, we identify that mTOR phosphorylates a mammalian homologue of Atg13 and the mammalian Atg1 homologues ULK1 and ULK2. The mammalian Atg13 binds both ULK1 and ULK2 and mediates the interaction of the ULK proteins with FIP200. The binding of Atg13 stabilizes and activates ULK and facilitates the phosphorylation of FIP200 by ULK, whereas knockdown of Atg13 inhibits autophagosome formation. Inhibition of mTOR by rapamycin or leucine deprivation, the conditions that induce autophagy, leads to dephosphorylation of ULK1, ULK2, and Atg13 and activates ULK to phosphorylate FIP200. These findings demonstrate that the ULK-Atg13-FIP200 complexes are direct targets of mTOR and important regulators of autophagy in response to mTOR signaling.
1,801 citations
TL;DR: The results showed that PPEF induces apoptosis only in gastric and breast cancer cell Lines, but not in lung, colon or liver cancer cell lines, Therefore, PPEf may have a significant potential as an organ-specific anti-cancer agent.
Abstract: Rhus verniciflua Stokes (RVS) is a plant with a long history of medicinal use in Eastern Asia. RVS has been widely used to treat gastritis, stomach cancer and atherosclerosis. The cytotoxic effects of different solvent fractions from an RVS ethanol extract were measured in 11 human cancer cell lines. The study showed that the ethyl-acetate (EtOAC) fraction was the most cytotoxic. This fraction contains a number of phenolic compounds, and this phenolic-rich EtOAC fraction was particularly effective against gastric and breast cancer cells. A purified phenolic-rich EtOAC fraction (PPEF) had a stronger apoptotic effect on these cells. Liquid chromatography-mass spectrometry (LC-MS) analysis showed that the PPEF contained gallic acid, protocatechuic acid, fisetin, sulfuretin, butein and 8 unknown compounds. There were only small amounts of flavonoids: fisetin, sulfuretin and butein. The results showed that PPEF induces apoptosis only in gastric and breast cancer cell lines, but not in lung, colon or liver cancer cell lines. Therefore, PPEF may have a significant potential as an organ-specific anti-cancer agent.
33 citations