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The role of mTORC1 and mTORC2 in UVB‐induced
Author(s) -
Lewis Martha,
Shantz Lisa
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.lb210
Subject(s) - mtorc2 , mtorc1 , pi3k/akt/mtor pathway , p70 s6 kinase 1 , protein kinase b , phosphorylation , microbiology and biotechnology , cancer research , biology , chemistry , signal transduction
Mammalian target of rapamycin (mTOR) plays an important role in cell proliferation and survival. mTOR has been shown to exist in at least two complexes, mTORC1 and mTORC2. mTORC1 is inhibited by rapamycin, contains the mTOR catalytic subunit as well as the proteins RAPTOR and mLST8. It shows that mTORC1 phosphorylates p70 S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E binding protein 1 (4EBP1). mTORC2 is known to be the kinase responsible for AKT phosphorylation on Serine 473 (S473). Based on previous research, we hypothesize that mTOR is a useful target in the prevention and treatment of nonmelanoma skin cancer. The goal of this project is to expand those results using wild‐type (WT) and RICTOR‐null (Rictor −/− ) mouse embryo fibroblasts (MEFs). Since phosphorylation of AKT on Threonine 308 (T308) has been reported to be facilitated by S473 phosphorylation, Aim is to determine the phosphorylation state of AKT T308 in WT and Rictor −/− cells, both with and without UVB treatment and to examine the effect of Torin‐2, which inhibits both complex on proliferation in WT and Rictor −/− MEFs. RESULTS Western blot analysis demonstrated that UVB exposure induces AKT phosphorylation at T308 in both cells suggesting that the absence of mTORC2 signaling does not prevent T308 phosphorylation in response to UVB. MTS analysis showed that mTORC1 inhibition with rapamycin had no significant effect on cell proliferation. Treatment of WT and Rictor −/− cells with Torin‐2 decreased proliferation in a dose‐dependent manner. Since TORC2 activity is absent in MEFs lacking Rictor, this result suggests the presence of a rapamycin‐insensitive mTORC1 activity that may play a role in cell proliferation.