mTORC2 is the hydrophobic motif kinase for SGK1

2008 ◽  
Vol 416 (3) ◽  
pp. e19-e21 ◽  
Author(s):  
Lijun Yan ◽  
Virginie Mieulet ◽  
Richard F. Lamb
Keyword(s):  
Protein Kinase ◽  
Catalytic Domain ◽  
Critical Role ◽  
Mammalian Target Of Rapamycin ◽  
Kinase C ◽  
Biochemical Journal ◽  
Dependent Protein ◽  
Hydrophobic Motif ◽  
Phosphoinositide 3 Kinase ◽  
A Site

The activation of the AGC (protein kinase A/protein kinase G/protein kinase C)-family kinase SGK1 (serum- and glucocorticoid-induced kinase 1) by insulin via PI3K (phosphoinositide 3-kinase) signalling has been appreciated for almost 10 years. PDK1 (phosphoinositide-dependent protein kinase 1), a kinase that phosphorylates the SGK1 catalytic domain at Thr256, is known to play a critical role in SGK1 activation. However, the identity of the protein kinase(s) responsible for phosphorylation of Ser422, a site outside the catalytic domain (the so-called hydrophobic motif, or HM) that promotes activation of the kinase by PDK1, was unclear. In work reported in this issue of the Biochemical Journal, García-Martínez and Alessi have revealed the identity of a ‘PDK2’ kinase that catalyses Ser422 phosphorylation as mTORC2 (mammalian target of rapamycin complex 2), a multiprotein kinase that phosphorylates a similar site in PKB (protein kinase B).

scholarly journals Proteomic Profile of Carbonylated Proteins Screen Regulation of Apoptosis via CaMK Signaling in Response to Regular Aerobic Exercise

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Wenfeng Liu ◽  
Li Li ◽  
Heyu Kuang ◽  
Yan Xia ◽  
Zhiyuan Wang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Aerobic Exercise ◽  
Protein Kinase B ◽  
Mammalian Target Of Rapamycin ◽  
Rat Striatum ◽  
Protective Effects ◽  
Sprague Dawley ◽  
Calcium Calmodulin Dependent ◽  
Dependent Protein ◽  
Phosphoinositide 3 Kinase

To research carbonylated proteins and screen molecular targets in the rat striatum on regular aerobic exercise, male Sprague-Dawley rats (13 months old, n = 24) were randomly divided into middle-aged sedentary control (M-SED) and aerobic exercise (M-EX) groups (n = 12 each). Maximum oxygen consumption (VO2max) gradually increased from 50%–55% to 65%–70% for a total of 10 weeks. A total of 36 carbonylated proteins with modified oxidative sites were identified by Electrospray Ionization-Quadrupole-Time of Flight-Mass Spectrometer (ESI-Q-TOF-MS), including 17 carbonylated proteins unique to the M-SED group, calcium/calmodulin-dependent protein kinase type II subunit beta (CaMKIIβ), and heterogeneous nuclear ribonucleoprotein A2/B1 (Hnrnpa2b1), among others, and 19 specific to the M-EX group, ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCH-L1), and malic enzyme, among others. Regular aerobic exercise improved behavioral and stereological indicators, promoted normal apoptosis (P < 0.01), alleviated carbonylation of the CaMKIIβ and Hnrnpa2b1, but induced carbonylation of the UCH-L1, and significantly upregulated the expression levels of CaMKIIβ, CaMKIIα, and Vdac1 (p < 0.01) and Hnrnpa2b1 and UCH-L1 (p < 0.01), as well as the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathways (PI3K/Akt/mTOR) pathway-related genes Akt and mTOR. Regular aerobic exercise for 10 weeks (incremental for the first 6 weeks followed by constant loading for 4 weeks) enhanced carbonylation of CaMKIIβ, Hnrnpa2b1, and modulated apoptosis via activation of CaMK and phosphoinositide 3-kinase/protein kinase B/mTOR signaling. It also promoted normal apoptosis in the rat striatum, which may have protective effects in neurons.

mTOR complex 2 (mTORC2) controls hydrophobic motif phosphorylation and activation of serum- and glucocorticoid-induced protein kinase 1 (SGK1)

2008 ◽  
Vol 416 (3) ◽  
pp. 375-385 ◽  
Author(s):  
Juan M. García-Martínez ◽  
Dario R. Alessi
Keyword(s):  
Protein Kinase ◽  
Mammalian Target Of Rapamycin ◽  
Kinase Domain ◽  
Vital Role ◽  
Interacting Protein ◽  
Cellular Processes ◽  
Kinase C ◽  
Forkhead Box ◽  
Hydrophobic Motif ◽  
Mcf 7

SGK1 (serum- and glucocorticoid-induced protein kinase 1) is a member of the AGC (protein kinase A/protein kinase G/protein kinase C) family of protein kinases and is activated by agonists including growth factors. SGK1 regulates diverse effects of extracellular agonists by phosphorylating regulatory proteins that control cellular processes such as ion transport and growth. Like other AGC family kinases, activation of SGK1 is triggered by phosphorylation of a threonine residue within the T-loop of the kinase domain and a serine residue lying within the C-terminal hydrophobic motif (Ser422 in SGK1). PDK1 (phosphoinositide-dependent kinase 1) phosphorylates the T-loop of SGK1. The identity of the hydrophobic motif kinase is unclear. Recent work has established that mTORC1 [mTOR (mammalian target of rapamycin) complex 1] phosphorylates the hydrophobic motif of S6K (S6 kinase), whereas mTORC2 (mTOR complex 2) phosphorylates the hydrophobic motif of Akt (also known as protein kinase B). In the present study we demonstrate that SGK1 hydrophobic motif phosphorylation and activity is ablated in knockout fibroblasts possessing mTORC1 activity, but lacking the mTORC2 subunits rictor (rapamycin-insensitive companion of mTOR), Sin1 (stress-activated-protein-kinase-interacting protein 1) or mLST8 (mammalian lethal with SEC13 protein 8). Furthermore, phosphorylation of NDRG1 (N-myc downstream regulated gene 1), a physiological substrate of SGK1, was also abolished in rictor-, Sin1- or mLST8-deficient fibroblasts. mTORC2 immunoprecipitated from wild-type, but not from mLST8- or rictor-knockout cells, phosphorylated SGK1 at Ser422. Consistent with mTORC1 not regulating SGK1, immunoprecipitated mTORC1 failed to phosphorylate SGK1 at Ser422, under conditions which it phosphorylated the hydrophobic motif of S6K. Moreover, rapamycin treatment of HEK (human embryonic kidney)-293, MCF-7 or HeLa cells suppressed phosphorylation of S6K, without affecting SGK1 phosphorylation or activation. The findings of the present study indicate that mTORC2, but not mTORC1, plays a vital role in controlling the hydrophobic motif phosphorylation and activity of SGK1. Our findings may explain why in previous studies phosphorylation of substrates, such as FOXO (forkhead box O), that could be regulated by SGK, are reduced in mTORC2-deficient cells. The results of the present study indicate that NDRG1 phosphorylation represents an excellent biomarker for mTORC2 activity.

A small-molecule inhibitor of D-cyclin transactivation displays preclinical efficacy in myeloma and leukemia via phosphoinositide 3-kinase pathway

Blood ◽  
2011 ◽  
Vol 117 (6) ◽  
pp. 1986-1997 ◽  
Author(s):  
Xinliang Mao ◽  
Biyin Cao ◽  
Tabitha E. Wood ◽  
Rose Hurren ◽  
Jiefei Tong ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mammalian Target Of Rapamycin ◽  
Leukemia Cell ◽  
Hematologic Malignancies ◽  
Intact Cells ◽  
Molecule Inhibitor ◽  
Dependent Protein ◽  
A Cell ◽  
Phosphoinositide 3 Kinase ◽  
Induced Apoptosis

Abstract D-cyclins are universally dysregulated in multiple myeloma and frequently overexpressed in leukemia. To better understand the role and impact of dysregulated D-cyclins in hematologic malignancies, we conducted a high-throughput screen for inhibitors of cyclin D2 transactivation and identified 8-ethoxy-2-(4-fluorophenyl)-3-nitro-2H-chromene (S14161), which inhibited the expression of cyclins D1, D2, and D3 and arrested cells at the G0/G1 phase. After D-cyclin suppression, S14161 induced apoptosis in myeloma and leukemia cell lines and primary patient samples preferentially over normal hematopoietic cells. In mouse models of leukemia, S14161 inhibited tumor growth without evidence of weight loss or gross organ toxicity. Mechanistically, S14161 inhibited the activity of phosphoinositide 3-kinase in intact cells and the activity of the phosphoinositide 3-kinases α, β, δ, and γ in a cell-free enzymatic assay. In contrast, it did not inhibit the enzymatic activities of other related kinases, including the mammalian target of rapamycin, the DNA-dependent protein kinase catalytic subunit, and phosphoinositide-dependent kinase-1. Thus, we identified a novel chemical compound that inhibits D-cyclin transactivation via the phosphoinositide 3-kinase/protein kinase B signaling pathway. Given its potent antileukemia and antimyeloma activity and minimal toxicity, S14161 could be developed as a novel agent for blood cancer therapy.

Lupeol Inhibits Proliferation and Promotes Apoptosis of Ovarian Cancer Cells by Inactivating Phosphoinositide-3-Kinase/Protein Kinase B/ Mammalian Target of Rapamycin Pathway

2020 ◽  
Vol 19 (2) ◽  
pp. 206-210
Author(s):  
Feng Chen ◽  
Bei Zhang
Keyword(s):  
Cell Cycle ◽  
Ovarian Cancer ◽  
Protein Kinase ◽  
Cell Viability ◽  
Cancer Cells ◽  
Protein Kinase B ◽  
Mammalian Target Of Rapamycin ◽  
Target Of Rapamycin ◽  
Ovarian Cancer Cells ◽  
Phosphoinositide 3 Kinase

Lupeol exhibits multiple pharmacological activities including, anticancerous, anti-inflammatory, and antioxidant. The aim of this study was to explore the anticancerous activity of lupeol on ovarian cancer cells and examine its mechanism of action. To this end, increasing concentrations of lupeol on cell viability, cell cycle, and apoptosis in Caov-3 cells were evaluated. Lupeol inhibited cell viability, induced G1 phase arrest in cell cycle, increased cell apoptosis, and inhibited the ratio of phospho-Akt/protein kinase B and phospho-mammalian target of rapamycin/mammalian target of rapamycin. In conclusion, these data suggest that lupeol may play a therapeutic role in ovarian cancer.

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