(R,S)-Ketamine Metabolites (R,S)-norketamine and (2S,6S)-hydroxynorketamine Increase the Mammalian Target of Rapamycin Function

Abstract Background: Subanesthetic doses of (R,S)-ketamine are used in the treatment of neuropathic pain and depression. In the rat, the antidepressant effects of (R,S)-ketamine are associated with increased activity and function of mammalian target of rapamycin (mTOR); however, (R,S)-ketamine is extensively metabolized and the contribution of its metabolites to increased mTOR signaling is unknown. Methods: Rats (n = 3 per time point) were given (R,S)-ketamine, (R,S)-norketamine, and (2S,6S)-hydroxynorketamine and their effect on the mTOR pathway determined after 20, 30, and 60 min. PC-12 pheochromocytoma cells (n = 3 per experiment) were treated with escalating concentrations of each compound and the impact on the mTOR pathway was determined. Results: The phosphorylation of mTOR and its downstream targets was significantly increased in rat prefrontal cortex tissue by more than ~2.5-, ~25-, and ~2-fold, respectively, in response to a 60-min postadministration of (R,S)-ketamine, (R,S)-norketamine, and (2S,6S)-hydroxynorketamine (P < 0.05, ANOVA analysis). In PC-12 pheochromocytoma cells, the test compounds activated the mTOR pathway in a concentration-dependent manner, which resulted in a significantly higher expression of serine racemase with ~2-fold increases at 0.05 nM (2S,6S)-hydroxynorketamine, 10 nM (R,S)-norketamine, and 1,000 nM (R,S)-ketamine. The potency of the effect reflected antagonistic activity of the test compounds at the α7-nicotinic acetylcholine receptor. Conclusions: The data demonstrate that (R,S)-norketamine and (2S,6S)-hydroxynorketamine have potent pharmacological activity both in vitro and in vivo and contribute to the molecular effects produced by subanesthetic doses of (R,S)-ketamine. The results suggest that the determination of the mechanisms underlying the antidepressant and analgesic effects of (R,S)-ketamine requires a full study of the parent compound and its metabolites.

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Targeting mammalian target of rapamycin: prospects for the treatment of inflammatory bowel diseases

Current Medicinal Chemistry ◽

10.2174/0929867327666200504081503 ◽

2020 ◽

Vol 27 ◽

Author(s):

Naser-Aldin Lashgari ◽

Nazanin Momeni Roudsari ◽

Saeideh Momtaz ◽

Negar Ghanaatian ◽

Parichehr Kohansal ◽

...

Keyword(s):

Signaling Pathway ◽

Mammalian Target Of Rapamycin ◽

Mtor Pathway ◽

Mtor Signaling ◽

Target Of Rapamycin ◽

In Vivo Studies ◽

Cochrane Library ◽

Mtor Signaling Pathway ◽

Inflammatory Bowel

: Inflammatory bowel disease (IBD) is a general term for a group of chronic and progressive disorders. Several cellular and biomolecular pathways are implicated in the pathogenesis of IBD, yet the etiology is unclear. Activation of the mammalian target of rapamycin (mTOR) pathway in the intestinal epithelial cells was also shown to induce inflammation. This review focuses on the inhibition of the mTOR signaling pathway and its potential application in treating IBD. We also provide an overview on plant-derived compounds that are beneficial for the IBD management through modulation of the mTOR pathway. Data were extracted from clinical, in vitro and in vivo studies published in English between 1995 and May 2019, which were collected from PubMed, Google Scholar, Scopus and Cochrane library databases. Results of various studies implied that inhibition of the mTOR signaling pathway downregulates the inflammatory processes and cytokines involved in IBD. In this context, a number of natural products might reverse the pathological features of the disease. Furthermore, mTOR provides a novel drug target for IBD. Comprehensive clinical studies are required to confirm the efficacy of mTOR inhibitors in treating IBD.

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T-2 Toxin Exposure Induces Apoptosis in TM3 Cells by Inhibiting Mammalian Target of Rapamycin/Serine/Threonine Protein Kinase(mTORC2/AKT) to Promote Ca2+Production

International Journal of Molecular Sciences ◽

10.3390/ijms19113360 ◽

2018 ◽

Vol 19 (11) ◽

pp. 3360 ◽

Cited By ~ 4

Author(s):

Ji Wang ◽

Chenglin Yang ◽

Zhihang Yuan ◽

Jine Yi ◽

Jing Wu

Keyword(s):

Cell Injury ◽

Mammalian Target Of Rapamycin ◽

Annexin V ◽

Target Of Rapamycin ◽

Dependent Manner ◽

Toxin Exposure ◽

Concentration Changes ◽

Vitro Model ◽

Induced Apoptosis

Although mTOR (the mammalian target of rapamycin) can regulate intracellular free Ca2+concentration in normal cultured podocytes, it remains elusive as to how mTORC2/AKT-mediated Ca2+participates in the process of T-2 toxin-induced apoptosis. The potential signaling responsible for intracellular Ca2+ concentration changes was investigated using immunoblot assays in an in vitro model of TM3 cell injury induced by T-2 toxin. Changes in Ca2+ were assessed using the Ca2+-sensitive fluorescent indictor dye Fura 2-AM. The cytotoxicity of TM3 cells was assessed with an MTT bioassay, and apoptosis was measured using Annexin V-FITC staining. Following T-2 toxin treatment, the growth of cells, phospho-mTORSer2481, phospho-mTORSer2448, and phospho-AktSer473 were significantly decreased in a time-dependent manner, whereas Ca2+ and apoptosis were increased. T-2 toxin-induced apoptosis was prevented by BAPTA-AM (a Ca2+chelator) and MHY1485 (an mTOR activator), and the application of mTOR activator MHY1485 also prevented the increase of intracellular free Ca2+concentration in TM3 cells. Our results strongly suggest that T-2 toxin exposure induces apoptosis in TM3 cells by inhibiting mTORC2/AKT to promote Ca2+ production.

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Design and Synthesis of C-19 Isosteviol Derivatives as Potent and Highly Selective Antiproliferative Agents

Molecules ◽

10.3390/molecules24010121 ◽

2018 ◽

Vol 24 (1) ◽

pp. 121 ◽

Cited By ~ 1

Author(s):

Tian Luan ◽

Li-Hua Cao ◽

Hao Deng ◽

Qing-Kun Shen ◽

Yu-Shun Tian ◽

...

Keyword(s):

Antiproliferative Activity ◽

Human Cancer ◽

Parent Compound ◽

Cyclin A ◽

Cyclin B1 ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

Cyclin E1 ◽

Hct 116

Six series of novel isosteviol derivatives; modified in the C-19 position; were synthesized; and their antiproliferative activity was evaluated against three human cancer cell lines (HCT-116; BEL-7402; HepG2) and the human L02 normal cell line in vitro. Most of the derivatives tested here exhibited improved antiproliferative activity with high selectivity when compared with the parent compound isosteviol and the positive control drug 5-fluorouracil. Among these derivatives; compound 5d exhibited the most potent antiproliferative activity and commendable selectivity between cancer and normal cells. In addition; compound 5d inhibited the colony formation of HCT-116 cells in a concentration-dependent manner. Further studies revealed that compound 5d arrested the HCT-116 cell cycle in the S phase; and western blot analysis demonstrated the mechanism may be correlated with a change in the expression of cyclin A; cyclin B1; and cyclin E1. Furthermore; the results of a docking study that involved placing compound 5d into the CDK2/cyclin A binding site revealed that its mode of action was possibly as a CDK2/cyclin A inhibitor.

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Cell-free Expression of Proton-Coupled Folate Transporter in the Presence of Nanodiscs

10.1101/2021.05.19.444806 ◽

2021 ◽

Author(s):

Hoa Quynh Do ◽

Carla M Bassil ◽

Elizabeth I Andersen ◽

Michaela Jansen

Keyword(s):

Tumor Cells ◽

Plasma Membranes ◽

In Vitro Translation ◽

Translation System ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

E Coli ◽

Membrane Scaffold ◽

The Impact

The Proton-Coupled Folate Transporter (PCFT) is a transmembrane transport protein that controls the absorption of dietary folates in the small intestine. PCFT also mediates uptake of chemotherapeutically used antifolates into tumor cells. PCFT has been identified within lipid rafts observed in phospholipid bilayers of plasma membranes, a micro environment that is altered in tumor cells. The present study aimed at investigating the impact of different lipids within Lipid-protein nanodiscs (LPNs), discoidal lipid structures stabilized by membrane scaffold proteins, to yield soluble PCFT expression in an E. coli lysate-based cell-free transcription/translation system. In the absence of detergents or lipids, we observed PCFT quantitatively as precipitate in this system. We then explored the ability of LPNs to support solubilized PCFT expression when present during in-vitro translation. LPNs consisted of either dimyristoyl phosphatidylcholine (DMPC), palmitoyl-oleoyl phosphatidylcholine (POPC), or dimyristoyl phosphatidylglycerol (DMPG). While POPC did not lead to soluble PCFT expression, both DMPG and DMPC supported PCFT translation directly into LPNs, the latter in a concentration dependent manner. The results obtained through this study provide insights into the lipid preferences of PCFT. Membrane-embedded or solubilized PCFT will enable further studies with diverse biophysical approaches to enhance the understanding of the structure and molecular mechanism of folate transport through PCFT.

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Curcumin Inhibits Joint Contracture through PTEN Demethylation and Targeting PI3K/Akt/mTOR Pathway in Myofibroblasts from Human Joint Capsule

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2019/4301238 ◽

2019 ◽

Vol 2019 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Ze Zhuang ◽

Dongjie Yu ◽

Zheng Chen ◽

Dezhao Liu ◽

Guohui Yuan ◽

...

Keyword(s):

Mammalian Target Of Rapamycin ◽

Clinical Problem ◽

Joint Contracture ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

Joint Injury ◽

Specific Pcr ◽

And Migration

Joint contracture is increasingly regarded as a clinical problem that leads to irreversible dysfunction of the joint. It is a pathophysiological process following joint injury, which is marked by the activation of myofibroblasts. There is currently no effective treatment for the prevention of joint contracture. Curcumin is a polyphenol pigment extracted from turmeric, which possesses anti-inflammatory, antioxidative, and antitumor properties. In the present study, we demonstrated that curcumin exerts a protective effect against joint contracture via the inhibition of myofibroblast proliferation and migration in a time- and concentration-dependent manner. Moreover, we indicated that phosphatase and tension homolog (PTEN) was downregulated in myofibroblasts in vitro and in the contracture capsule tissues of patients in vivo. Additionally, western blot analysis revealed a negative correlation between the expression levels of PTEN and the fibrosis marker protein alpha smooth muscle cell actin. Methylation-specific PCR results suggested that curcumin was able to demethylate PTEN in a similar manner to the demethylation agent 5-azacytidine, increasing PTEN expression and further inhibiting phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signaling. In conclusion, our data illustrate part of the mechanism of curcumin inhibition in joint contracture. These results support the hypothesis that curcumin may potentially be used as a novel candidate for the treatment of joint contracture.

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Prolactin activates mammalian target-of-rapamycin through phosphatidylinositol 3-kinase and stimulates phosphorylation of p70S6K and 4E-binding protein-1 in lymphoma cells

Journal of Endocrinology ◽

10.1677/joe.1.06368 ◽

2006 ◽

Vol 190 (2) ◽

pp. 307-312 ◽

Cited By ~ 24

Author(s):

Jessica D Bishop ◽

Wei Lun Nien ◽

Shauna M Dauphinee ◽

Catherine K L Too

Keyword(s):

Binding Protein ◽

Mammalian Target Of Rapamycin ◽

Mtor Pathway ◽

Target Of Rapamycin ◽

Dependent Manner ◽

Phosphatidylinositol 3 Kinase ◽

Lymphoma Cells ◽

Nb2 Cells ◽

Initiation Of Translation ◽

Phosphatidylinositol 3

Mitogens activate the mammalian target-of-rapamycin (mTOR) pathway through phosphatidylinositol 3-kinase (PI3K). The activated mTOR kinase phosphorylates/ activates ribosomal protein S6 kinase (p70S6K) and phosphorylates/inactivates eukaryotic initiation factor 4E-binding protein-1 (4E-BP1), resulting in the initiation of translation and cell-cycle progression. The prolactin receptor signaling cascade has been implicated in crosstalk with the mTOR pathway, but whether prolactin (PRL) directly activates mTOR is not known. This study showed that PRL stimulated the phosphorylation of mTOR, p70S6K, Akt, and Jak2 kinases in a dose- and time-dependent manner in PRL-dependent rat Nb2 lymphoma cells. PRL-stimulated phosphorylation of mTOR was detected as early as 10 min, closely following the phosphorylation of Akt (upstream of mTOR), but preceding that of the downstream p70S6K. PRL activation of mTOR was inhibited by rapamycin (mTOR inhibitor), LY249002, and wortmannin (P13K inhibitors), but not by AG490 (Jak2 inhibitor), indicating that it was mediated by the P13K/Akt, but not Jak2, pathway. PRL also stimulated phosphorylation of 4E-BP1 in Nb2 cells. PRL-induced phosphorylation of p70S6K and 4E-BP1 was inhibited by rapamycin, but not by okadaic acid (inhibitor of protein phosphatase, PP2A). PRL induced a transient interaction between p70S6K and the catalytic subunit of PP2A (PP2Ac) in 1 and 2 h, whereas a PP2Ac–4E-BP1 complex was constitutively present in quiescent and PRL-treated Nb2 cells. These results suggested that p70S6K and 4E-BP1 were substrates of PP2A and the inhibition of mTOR promoted their dephosphorylation by PP2A. In summary, PRL-stimulated phosphorylation of mTOR is mediated by PI3K. PRL-activated mTOR may phosphorylate p70S6K and 4E-BP1 by restraining PP2A.

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Mammalian target of rapamycin (mTOR) regulates both proliferation of megakaryocyte progenitors and late stages of megakaryocyte differentiation

Blood ◽

10.1182/blood-2005-07-3005 ◽

2006 ◽

Vol 107 (6) ◽

pp. 2303-2310 ◽

Cited By ~ 60

Author(s):

Hana Raslova ◽

Véronique Baccini ◽

Lamya Loussaief ◽

Béatrice Comba ◽

Jérôme Larghero ◽

...

Keyword(s):

Mammalian Target Of Rapamycin ◽

Mtor Pathway ◽

Cyclin D3 ◽

Target Of Rapamycin ◽

Transcriptional Level ◽

The Mean ◽

Late Stages ◽

Megakaryocyte Progenitors ◽

Megakaryocyte Differentiation

AbstractA major determinant in platelet production is the megakaryocyte (MK) size that is regulated both by ploidization and the increase in cytoplasmic volume at the end of maturation. Here we investigated the involvement of the mammalian target of rapamycin (mTOR) pathway in the regulation of megakaryopoiesis. We show that phosphorylation of mTOR, p70S6K1, and 4E-BP1 was diminished in thrombopoietin-cultured human MKs after rapamycin treatment. Rapamycin induced an inhibition in the G1/S transition and a decrease in the mean MK ploidy via a diminution of p21 and cyclin D3 occurring at a transcriptional level. Both cycling (2N/4N) and polyploid (8N/16N) MKs were reduced in size, with a size reduction slightly more pronounced in mature polyploid MKs than in immature ones. Rapamycin also induced a delay in the expression of MK markers and prevented the generation of proplatelet MKs. Additional experiments performed in vitro with MKs from mutant mice showed that the decrease in mean ploidy level and the delay in MK differentiation in the presence of rapamycin were less pronounced in CdknIa (p21)–/– MKs than in CdknIa (p21)+/+ MKs. These findings indicate that the mTOR pathway plays an important role during megakaryopoiesis by regulating ploidy, cell size, and maturation, in part by regulating p21 and cyclin D3.

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Mammalian target of rapamycin (mTOR) pathway signalling in lymphomas

Expert Reviews in Molecular Medicine ◽

10.1017/s1462399408000586 ◽

2008 ◽

Vol 10 ◽

Cited By ~ 24

Author(s):

Elias Drakos ◽

George Z. Rassidakis ◽

L. Jeffrey Medeiros

Keyword(s):

Mammalian Target Of Rapamycin ◽

Central Element ◽

Mtor Inhibitors ◽

Chemotherapeutic Agents ◽

Mtor Pathway ◽

Target Of Rapamycin ◽

In Vivo Studies ◽

Mtor Inhibition

AbstractThe mammalian target of rapamycin mTOR is a central element in an evolutionary conserved signalling pathway that regulates cell growth, survival and proliferation, orchestrating signals originating from growth factors, nutrients or particular stress stimuli. Two important modulators of mTOR activity are the AKT and ERK/MAPK signalling pathways. Many studies have shown that mTOR plays an important role in the biology of malignant cells, including deregulation of the cell cycle, inactivation of apoptotic machinery and resistance to chemotherapeutic agents. The development of several mTOR inhibitors, in addition to rapamycin, has facilitated studies of the role of mTOR in cancer, and verified the antitumour effect of mTOR inhibition in many types of neoplasms, including lymphomas. Clinical trials of rapamycin derivatives in lymphoma patients are already in development and there are encouraging preliminary results, such as the substantial response of a subset of mantle cell lymphoma patients to the rapamycin analogue temsirolimus. Based on results obtained from in vitro and in vivo studies of the mTOR pathway in lymphomas, it seems that better understanding of mTOR regulation will reveal aspects of lymphomagenesis and contribute to the development of more powerful, targeted therapies for lymphoma patients.

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2-Hydroxy-4-Methylbenzoic Anhydride Inhibits Neuroinflammation in Cellular and Experimental Animal Models of Parkinson’s Disease

International Journal of Molecular Sciences ◽

10.3390/ijms21218195 ◽

2020 ◽

Vol 21 (21) ◽

pp. 8195

Author(s):

Soo-Yeol Song ◽

In-Su Kim ◽

Sushruta Koppula ◽

Ju-Young Park ◽

Byung-Wook Kim ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Parent Compound ◽

Intraperitoneal Administration ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

Necrosis Factor Alpha ◽

Protein Levels

Microglia-mediated neuroinflammation is one of the key mechanisms involved in acute brain injury and chronic neurodegeneration. This study investigated the inhibitory effects of 2-hydroxy-4-methylbenzoic anhydride (HMA), a novel synthetic derivative of HTB (3-hydroxy-4-trifluoromethylbenzoic acid) on neuroinflammation and underlying mechanisms in activated microglia in vitro and an in vivo mouse model of Parkinson’s disease (PD). In vitro studies revealed that HMA significantly inhibited lipopolysaccharide (LPS)-stimulated excessive release of nitric oxide (NO) in a concentration dependent manner. In addition, HMA significantly suppressed both inducible NO synthase and cyclooxygenase-2 (COX-2) at the mRNA and protein levels in LPS-stimulated BV-2 microglia cells. Moreover, HMA significantly inhibited the proinflammatory cytokines such as interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha in LPS-stimulated BV-2 microglial cells. Furthermore, mechanistic studies ensured that the potent anti-neuroinflammatory effects of HMA (0.1, 1.0, and 10 μM) were mediated by phosphorylation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) in LPS-stimulated BV-2 cells. In vivo evaluations revealed that intraperitoneal administration of potent neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 20 mg/kg, four times a 1 day) in mice resulted in activation of microglia in the brain in association with severe behavioral deficits as assessed using a pole test. However, prevention of microglial activation and attenuation of Parkinson’s disease (PD)-like behavioral changes was obtained by oral administration of HMA (30 mg/kg) for 14 days. Considering the overall results, our study showed that HMA exhibited strong anti-neuroinflammatory effects at lower concentrations than its parent compound. Further work is warranted in other animal and genetic models of PD for evaluating the efficacy of HMA to develop a potential therapeutic agent in the treatment of microglia-mediated neuroinflammatory disorders, including PD.

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