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M.S., National Chung-Hsing University-2002
Thesis Advisor: Estela Jacinto, Ph.D.
Graduate Program in Physiology & Integrated Biology
RWJMS Research Tower
Friday, September 28, 2012
The mechanistic target of rapamycin (mTOR), an atypical protein kinase with homology to lipid kinases, is the catalytic subunit of two structurally and functionally distinct protein complexes, mTORC1 and mTORC2. The mTORCs modulate diverse cellular functions in response to extracellular signals such as nutrients, energy, growth factors and hormones. Compared to mTORC1, mTORC2 was lately identified and its functions are not well explored. In this thesis, we reported a novel prospect of mTORC2 functions in advancing the stability and maturation of newly synthesized proteins. We first revealed the interaction between mTORC2 and translating ribosomes (polysomes), wherein mTORC2 mediates co-translational phosphorylation at Akt turn motif (TM) to stabilize these nascent polypeptides. Besides, we discovered that mTORC2 indirectly regulates protein N-linked glycosylation, which plays an important role during the maturation of membrane and secretory proteins. By stabilizing GFAT1 proteins, mTORC2 controls the hexosamine biosynthesis pathway to maintain the adequate level of UDP-N-acetylglucosamine (UDPGN) for N-glycosylation. These findings extend our knowledge of mTORC2 on orchestrating other signaling pathways by stabilizing kinase molecules and promoting surface localization of membrane receptors.