mTORC2
mTOR | |
---|---|
Identifiers | |
Symbol | MTOR |
Alt. symbols | FRAP, FRAP2, FRAP1 |
Entrez | 2475 |
HUGO | 3942 |
OMIM | 601231 |
RefSeq | NM_004958 |
UniProt | P42345 |
Other data | |
EC number | 2.7.11.1 |
Locus | Chr. 1 p36 |
RICTOR | |
---|---|
Identifiers | |
Symbol | RICTOR |
Entrez | 253260 |
HUGO | 28611 |
RefSeq | NM_152756 |
Other data | |
Locus | Chr. 5 p13.1 |
MLST8 | |
---|---|
Identifiers | |
Symbol | MLST8 |
Entrez | 64223 |
HUGO | 24825 |
OMIM | 612190 |
RefSeq | NM_022372 |
UniProt | Q9BVC4 |
Other data | |
Locus | Chr. 16 p13.3 |
MAPKAP1 | |
---|---|
Identifiers | |
Symbol | MAPKAP1 |
Entrez | 79109 |
HUGO | 18752 |
OMIM | 610558 |
RefSeq | NM_001006617.1 |
UniProt | Q9BPZ7 |
Other data | |
Locus | Chr. 9 q34.11 |
mTOR Complex 2 (mTORC2) is a protein complex that regulates cellular metabolism as well as the cytoskeleton. It is defined by the interaction of mTOR and the rapamycin-insensitive companion of mTOR (RICTOR), and also includes GβL, mammalian stress-activated protein kinase interacting protein 1 (mSIN1), as well as Protor 1/2, DEPTOR, and TTI1 and TEL2.[1][2][3]
Function
mTORC2 has been shown to function as an important regulator of the cytoskeleton through its stimulation of F-actin stress fibers, paxillin, RhoA, Rac1, Cdc42, and protein kinase C α (PKCα).[2]
mTORC2 also regulates cellular metabolism, in part through the regulation of Akt/PKB and the serum-and glucocorticoid-induced protein kinase SGK. mTORC2 phosphorylates the serine/threonine protein kinase Akt/PKB at a serine residue S473 as well as serine residue S450. Phosphorylation of the serine stimulates Akt phosphorylation at a threonine T308 residue by PDK1 and leads to full Akt activation.[4][5] Curcumin inhibits both by preventing phosphorylation of the serine.[6] Moreover, mTORC2 activity has been implicated in the regulation of autophagy.[7][8]
Regulation
mTORC2 appears to be regulated by insulin, growth factors, serum, and nutrient levels.[1] Originally, mTORC2 was identified as a rapamycin-insensitive entity, as acute exposure to rapamycin did not affect mTORC2 activity or Akt phosphorylation.[4] However, subsequent studies have shown that, at least in some cell lines, chronic exposure to rapamycin, while not affecting pre-existing mTORC2s, promotes rapamycin inhibition of free mTOR molecules, thus inhibiting the formation of new mTORC2.[9] mTORC2 can be inhibited by chronic treatment with rapamycin in vivo, both in cancer cells and normal tissues such as the liver and adipose tissue.[10][11] Torin1 can also be used to inhibit mTORC2.[8][12]
Localization of mTORC2 in the cell has been suggested to be at the plasma membrane; however, this may be due to its association with Akt.[13]
mTORC2 activation has thought to be due to growth factors, given that it regulates the activity of Akt and PKC.[4]
mTORC2 may play a role in cancer, given its regulation of the widely studied oncogenetic Akt pathway.[10]
Rictor has been shown to be the scaffold protein for substrate binding to mTORC2.[14]
Studies using mice with tissue-specific loss of Rictor, and thus inactive mTORC2, have found that mTORC2 plays a critical role in the regulation of glucose homeostasis. Liver-specific disruption of mTORC2 through hepatic deletion of the gene Rictor leads to glucose intolerance, hepatic insulin resistance, decreased hepatic lipogenesis, and decreased male lifespan.[15][16][17][18] Adipose-specific disruption of mTORC2 through deletion of Rictor may protect from a high-fat diet in young mice,[19] but results in hepatic steatosis and insulin resistance in older mice.[20] Loss of mTORC2/Rictor in pancreatic beta cells results in reduced beta cell mass and insulin secretion, and hyperglycemia and glucose intolerance.[21]
References
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External links
- TOR complex 2 at the US National Library of Medicine Medical Subject Headings (MeSH)}