YANK2 activated by Fyn promotes glioma tumorigenesis via the mTOR-independent p70S6K activation pathway.

Glioma, particularly glioblastomas (GBM), is incurable brain tumor. The most targeted receptor tyrosine kinase (RTKs) drugs did not bring benefit to GBM patients. The mechanism of glioma growth continues to be explored to find more effective treatment. Here, we reported that Ser/Thr protein kinase YANK2 (yet another kinase 2) is upregulated in glioma tissues and promotes the growth and proliferation of glioma in vitro and in vivo. Further, we confirmed that oncogene Fyn directly activated YANK2 through phosphorylation its Y110, and Fyn-mediated YANK2 phosphorylation at Y110 site promotes glioma growth by increasing its stability. Finally, YANK2 was proved to be a novel upstream kinase of p70S6K and promotes glioma growth by directly phosphorylating p70S6K at T389. Taken together, we found a new mTOR-independent p70S6K activation pathway, Fyn-YANK2-p70S6K, which promotes glioma growth, and YANK2 is a potential oncogene and serves as a novel therapeutic target for glioma.

mTORC1/S6K1 signaling promotes sustained oncogenic translation through modulating CRL3IBTK-mediated ubiquitination of eIF4A1 in cancer cells.

Enhanced protein synthesis is a crucial molecular mechanism that allows cancer cells to survive, proliferate, metastasize, and develop resistance to anti-cancer treatments, and often arises as a consequence of increased signaling flux channeled to mRNA-bearing eukaryotic initiation factor 4F (eIF4F). However, the post-translational regulation of eIF4A1, an ATP-dependent RNA helicase and subunit of the eIF4F complex, is still poorly understood. Here, we demonstrate that IBTK, a substrate-binding adaptor of the Cullin 3-RING ubiquitin ligase (CRL3) complex, interacts with eIF4A1. The non-degradative ubiquitination of eIF4A1 catalyzed by the CRL3IBTK complex promotes cap-dependent translational initiation, nascent protein synthesis, oncogene expression, and cervical tumor cell growth both in vivo and in vitro. Moreover, we show that mTORC1 and S6K1, two key regulators of protein synthesis, directly phosphorylate IBTK to augment eIF4A1 ubiquitination and sustained oncogenic translation. This link between the CRL3IBTK complex and the mTORC1/S6K1 signaling pathway, which is frequently dysregulated in cancer, represents a promising target for anti-cancer therapies.

Ginsenoside Rg1 Induces Autophagy in Colorectal Cancer through Inhibition of the Akt/mTOR/p70S6K Pathway.

This study aimed to elucidate the anti-colon cancer mechanism of ginsenoside Rg1 in vitro and in vivo. Cell viability rate was detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tetrazolium assay. The inhibitory effect of ginsenoside Rg1 against CT26 cell proliferation gradually increased with increasing concentration. The in vivo experiments also demonstrated an antitumor effect. The monodansylcadaverine (MDC), transmission electron microscopy (TEM), and expression of autophagy marker proteins confirmed that ginsenoside Rg1 induced autophagy in vitro. Ginsenoside Rg1 induced autophagy death of CT26 cells, but this effect could be diminished by autophagy inhibitor (3-methyladenine, 3-MA). Additionally, in a xenograft model, immunohistochemical analysis of tumor tissues showed that the LC3 and Beclin-1 proteins were highly expressed in the tumors from the ginsenoside Rg1-treated nude mice, confirming that ginsenoside Rg1 also induced autophagy in vivo. Furthermoer, both in vivo and in vitro, the protein expressions of p-Akt, p-mTOR, and p-p70S6K were inhibited by ginsenoside Rg1, which was verified by Akt inhibitors. These results indicated that the mechanism of ginsenoside Rg1 against colon cancer was associated with autophagy through inhibition of the Akt/mTOR/p70S6K signaling pathway.

Inhibition of p70 Ribosomal S6 Kinase (S6K1) Reduces Cortical Blood Flow in a Rat Model of Autism-Tuberous Sclerosis.

The manifestations of tuberous sclerosis complex (TSC) in humans include epilepsy, autism spectrum disorders (ASD) and intellectual disability. Previous studies suggested the linkage of TSC to altered cerebral blood flow and metabolic dysfunction. We previously reported a significant elevation in cerebral blood flow in an animal model of TSC and autism of young Eker rats. Inhibition of the mammalian target of rapamycin (mTOR) by rapamycin could restore normal oxygen consumption and cerebral blood flow. In this study, we investigated whether inhibiting a component of the mTOR signaling pathway, p70 ribosomal S6 kinase (S6K1), would yield comparable effects. Control Long Evans and Eker rats were divided into vehicle and PF-4708671 (S6K1 inhibitor, 75 mg/kg for 1 h) treated groups. Cerebral regional blood flow (14C-iodoantipyrine) was determined in isoflurane anesthetized rats. We found significantly increased basal cortical (+ 32%) and hippocampal (+ 15%) blood flow in the Eker rats. PF-4708671 significantly lowered regional blood flow in the cortex and hippocampus of the Eker rats. PF-4708671 did not significantly lower blood flow in these regions in the control Long Evans rats. Phosphorylation of S6-Ser240/244 and Akt-Ser473 was moderately decreased in Eker rats but only the latter reached statistical significance upon PF-4708671 treatment. Our findings suggest that moderate inhibition of S6K1 with PF-4708671 helps to restore normal cortical blood flow in Eker rats and that this information might have therapeutic potential in tuberous sclerosis complex and autism.

Dietary salt promotes cognition impairment through GLP-1R/mTOR/p70S6K signaling pathway.

Dietary salt has been associated with cognitive impairment in mice, possibly related to damaged synapses and tau hyperphosphorylation. However, the mechanism underlying how dietary salt causes cognitive dysfunction remains unclear. In our study, either a high-salt (8%) or normal diet (0.5%) was used to feed C57BL/6 mice for three months, and N2a cells were cultured in normal medium, NaCl medium (80 mM), or NaCl (80 mM) + Liraglutide (200 nM) medium for 48 h. Cognitive function in mice was assessed using the Morris water maze and shuttle box test, while anxiety was evaluated by the open field test (OPT). Western blotting (WB), immunofluorescence, and immunohistochemistry were utilized to assess the level of Glucagon-like Peptide-1 receptor (GLP-1R) and mTOR/p70S6K pathway. Electron microscope and western blotting were used to evaluate synapse function and tau phosphorylation. Our findings revealed that a high salt diet (HSD) reduced the level of synaptophysin (SYP) and postsynaptic density 95 (PSD95), resulting in significant synaptic damage. Additionally, hyperphosphorylation of tau at different sites was detected. The C57BL/6 mice showed significant impairment in learning and memory function compared to the control group, but HSD did not cause anxiety in the mice. In addition, the level of GLP-1R and autophagy flux decreased in the HSD group, while the level of mTOR/p70S6K was upregulated. Furthermore, liraglutide reversed the autophagy inhibition of N2a treated with NaCl. In summary, our study demonstrates that dietary salt inhibits the GLP-1R/mTOR/p70S6K pathway to inhibit autophagy and induces synaptic dysfunction and tau hyperphosphorylation, eventually impairing cognitive dysfunction.

ß-Hydroxy-ß-methylbutyrate (HMB) leads to phospholipase D2 (PLD2) activation and alters circadian rhythms in myotubes.

ß-Hydroxy-ß-methylbutyrate (HMB) is a breakdown product of leucine, which promotes muscle growth. Although some studies indicate that HMB activates AKT and mTOR, others show activation of the downstream effectors, P70S6K and S6, independent of mTOR. Our aim was to study the metabolic effect of HMB around the circadian clock in order to determine more accurately the signaling pathway involved. C2C12 myotubes were treated with HMB and clock, metabolic and myogenic markers were measured around the clock. HMB-treated C2C12 myotubes showed no activation of AKT and mTOR, but did show activation of P70S6K and S6. Activation of P70S6K and S6 was also found when myotubes were treated with HMB combined with metformin, an indirect mTOR inhibitor, or rapamycin, a direct mTOR inhibitor. The activation of the P70S6K and S6 independent of AKT and mTOR, was accompanied by increased activation of phospholipase D2 (PLD). In addition, HMB led to high amplitude and advanced circadian rhythms. In conclusion, HMB induces myogenesis in C2C12 by activating P70S6K and S6 via PLD2, rather than AKT and mTOR, leading to high amplitude advanced rhythms.

Acevaltrate promotes apoptosis and inhibits proliferation by suppressing HIF-1α accumulation in cancer cells.

Acevaltrate is a natural product isolated from the roots of Valeriana glechomifolia F.G.Mey. (Valerianaceae) and has been shown to exhibit anti-cancer activity. However, the mechanism by which acevaltrate inhibits tumor growth is not fully understood. We here demonstrated the effect of acevaltrate on hypoxia-inducible factor-1α (HIF-1α) expression. Acevaltrate showed a potent inhibitory activity against HIF-1α induced by hypoxia in various cancer cells. This compound markedly decreased the hypoxia-induced accumulation of HIF-1α protein dose-dependently. Further analysis revealed that acevaltrate inhibited HIF-1α protein synthesis and promoted degradation of HIF-1α protein, without affecting the expression level of HIF-1α mRNA. Moreover, the phosphorylation levels of mammalian target of rapamycin (mTOR), ribosomal protein S6 kinase (p70S6K), and eIF4E binding protein-1 (4E-BP1) were significantly suppressed by acevaltrate. In addition, acevaltrate promoted apoptosis and inhibited proliferation, which was potentially mediated by suppression of HIF-1α. We also found that acevaltrate administration inhibited tumor growth in mouse xenograft model. Taken together, these results suggested that acevaltrate was a potent inhibitor of HIF-1α and provided a new insight into the mechanisms of acevaltrate against cancers.

Computer-assisted discovery and evaluation of potential ribosomal protein S6 kinase beta 2 inhibitors.

S6K2 is an important protein in mTOR signaling pathway and cancer. To identify potential S6K2 inhibitors for mTOR pathway treatment, a virtual screening of 1,575,957 active molecules was performed using PLANET, AutoDock GPU, and AutoDock Vina, with their classification abilities compared. The MM/PB(GB)SA method was used to identify four compounds with the strongest binding energies. These compounds were further investigated using molecular dynamics (MD) simulations to understand the properties of the S6K2/ligand complex. Due to a lack of available 3D structures of S6K2, OmegaFold served as a reliable 3D predictive model with higher evaluation scores in SAVES v6.0 than AlphaFold, AlphaFold2, and RoseTTAFold2. The 150 ns MD simulation revealed that the S6K2 structure in aqueous solvation experienced compression during conformational relaxation and encountered potential energy traps of about 19.6 kJ mol-1. The virtual screening results indicated that Lys75 and Lys99 in S6K2 are key binding sites in the binding cavity. Additionally, MD simulations revealed that the ligands remained attached to the activation cavity of S6K2. Among the compounds, compound 1 induced restrictive dissociation of S6K2 in the presence of a flexible region, compound 8 achieved strong stability through hydrogen bonding with Lys99, compound 9 caused S6K2 tightening, and the binding of compound 16 was heavily influenced by hydrophobic interactions. This study suggests that these four potential inhibitors with different mechanisms of action could provide potential therapeutic options.

Huayu Qutan Recipe promotes lipophagy and cholesterol efflux through the mTORC1/TFEB/ABCA1-SCARB1 signal axis.

This study aims to investigate the mechanism of the anti-atherosclerosis effect of Huayu Qutan Recipe (HYQT) on the inhibition of foam cell formation. In vivo, the mice were randomly divided into three groups: CTRL group, MOD group and HYQT group. The HYQT group received HYQT oral administration twice a day (20.54 g/kg/d), and the plaque formation in ApoE-/- mice was observed using haematoxylin-eosin (HE) staining and oil red O (ORO) staining. The co-localization of aortic macrophages and lipid droplets (LDs) was examined using fluorescent labelling of CD11b and BODIPY fluorescence probe. In vitro, RAW 264.7 cells were exposed to 50 µg/mL ox-LDL for 48 h and then treated with HYQT for 24 h. The accumulation of LDs was evaluated using ORO and BODIPY. Cell viability was assessed using the CCK-8 assay. The co-localization of LC3b and BODIPY was detected via immunofluorescence and fluorescence probe. LysoTracker Red and BODIPY 493/503 were used as markers for lysosomes and LDs, respectively. Autophagosome formation were observed via transmission electron microscopy. The levels of LC3A/B II/LC3A/B I, p-mTOR/mTOR, p-4EBP1/4EBP1, p-P70S6K/P70S6K and TFEB protein level were examined via western blotting, while SQSTM1/p62, Beclin1, ABCA1, ABCG1 and SCARB1 were examined via qRT-PCR and western blotting. The nuclear translocation of TFEB was detected using immunofluorescence. The components of HYQT medicated serum were determined using Q-Orbitrap high-resolution MS analysis. Molecular docking was employed to identify the components of HYQT medicated serum responsible for the mTOR signalling pathway. The mechanism of taurine was illustrated. HYQT has a remarkable effect on atherosclerotic plaque formation and blood lipid level in ApoE-/- mice. HYQT decreased the co-localization of CD11b and BODIPY. HYQT (10% medicated serum) reduced the LDs accumulation in RAW 264.7 cells. HYQT and RAPA (rapamycin, a mTOR inhibitor) could promote cholesterol efflux, while chloroquine (CQ, an autophagy inhibitor) weakened the effect of HYQT. Moreover, MHY1485 (a mTOR agonist) also mitigated the effects of HYQT by reduced cholesterol efflux. qRT-PCR and WB results suggested that HYQT improved the expression of the proteins ABCA1, ABCG1 and SCARB1.HYQT regulates ABCA1 and SCARB1 protein depending on the mTORC1/TFEB signalling pathway. However, the activation of ABCG1 does not depend on this pathway. Q-Orbitrap high-resolution MS analysis results demonstrated that seven core compounds have good binding ability to the mTOR protein. Taurine may play an important role in the mechanism regulation. HYQT may reduce cardiovascular risk by promoting cholesterol efflux and degrading macrophage-derived foam cell formation. It has been observed that HYQT and ox-LDL regulate lipophagy through the mTOR/TFEB signalling pathway, rather than the mTOR/4EBP1/P70S6K pathway. Additionally, HYQT is found to regulate cholesterol efflux through the mTORC1/TFEB/ABCA1-SCARB1 signal axis, while taurine plays a significant role in lipophagy.

Iron overload promotes hemochromatosis-associated osteoarthritis via the mTORC1-p70S6K/4E-BP1 pathway.

BACKGROUNDS: Joint iron overload in hemochromatosis induces M1 polarization in synovial macrophages, releasing pro-inflammatory factors and leading to osteoarthritis development. However, the mechanism by which iron overload regulates M1 polarization remains unclear. This study aims to elucidate the mechanism by which synovial iron overload promotes macrophage M1 polarization. METHODS: In vitro, RAW264.7 macrophages were treated with iron and divided into five groups based on the concentration of the iron chelator, desferrioxamine (DFO): Ctrl, Fe, DFO1, DFO2, and DFO3. In vivo, rats were categorized into five groups based on iron overload and intra-articular DFO injection: A-Ctrl, A-Fe, A-DFO1, A-DFO2, and A-DFO3. Osteoarthritis was induced by transecting the left knee anterior cruciate ligament. Macrophage morphology was observed; Prussian Blue staining quantified iron deposition in macrophages, synovium, and liver; serum iron concentration was measured using the ferrozine method; cartilage damage was assessed using H&E and Safranin O-Fast Green staining; qPCR detected iNOS and Arg-1 expression; Western Blot analyzed the protein expression of iNOS, Arg-1, 4E-BP1, phosphorylated 4E-BP1, p70S6K, and phosphorylated p70S6K; ELISA measured TNF-α and IL-6 concentrations in supernatants; and immunohistochemistry examined the protein expression of F4/80, iNOS, Arg-1, 4E-BP1, phosphorylated 4E-BP1, p70S6K, and phosphorylated p70S6K in the synovium. RESULTS: In vitro, iron-treated macrophages exhibited Prussian Blue staining indicative of iron overload and morphological changes towards M1 polarization. qPCR and Western Blot revealed increased expression of the M1 polarization markers iNOS and its protein. ELISA showed elevated TNF-α and IL-6 levels in supernatants. In vivo, ferrozine assay indicated significantly increased serum iron concentrations in all groups except A-Ctrl; Prussian Blue staining showed increased liver iron deposition in all groups except A-Ctrl. Iron deposition in rat synovium decreased in a DFO concentration-dependent manner; immunohistochemistry showed a corresponding decrease in iNOS and phosphorylated 4E-BP1 expression, and an increase in Arg-1 expression. CONCLUSION: Intracellular iron overload may exacerbate joint cartilage damage by promoting synovial macrophage M1 polarization through phosphorylation of 4E-BP1 in the mTORC1-p70S6K/4E-BP1 pathway.

Capivasertib combines with docetaxel to enhance anti-tumour activity through inhibition of AKT-mediated survival mechanisms in prostate cancer.

BACKGROUND/OBJECTIVE: To explore the anti-tumour activity of combining AKT inhibition and docetaxel in PTEN protein null and WT prostate tumours. METHODS: Mechanisms associated with docetaxel capivasertib treatment activity in prostate cancer were examined using a panel of in vivo tumour models and cell lines. RESULTS: Combining docetaxel and capivasertib had increased activity in PTEN null and WT prostate tumour models in vivo. In vitro short-term docetaxel treatment caused cell cycle arrest in the majority of cells. However, a sub-population of docetaxel-persister cells did not undergo G2/M arrest but upregulated phosphorylation of PI3K/AKT pathway effectors GSK3ß, p70S6K, 4E-BP1, but to a lesser extent AKT. In vivo acute docetaxel treatment induced p70S6K and 4E-BP1 phosphorylation. Treating PTEN null and WT docetaxel-persister cells with capivasertib reduced PI3K/AKT pathway activation and cell cycle progression. In vitro and in vivo it reduced proliferation and increased apoptosis or DNA damage though effects were more marked in PTEN null cells. Docetaxel-persister cells were partly reliant on GSK3ß as a GSK3ß inhibitor AZD2858 reversed capivasertib-induced apoptosis and DNA damage. CONCLUSION: Capivasertib can enhance anti-tumour effects of docetaxel by targeting residual docetaxel-persister cells, independent of PTEN status, to induce apoptosis and DNA damage in part through GSK3ß.

Sestrin 2 protects human lens epithelial cells from oxidative stress and apoptosis induced by hydrogen peroxide by regulating the mTOR/Nrf2 pathway.

OBJECTIVE: We aimed to explore the effect and potential mechanism of Sestrin 2 (SESN2) in human lens epithelial cells (HLECs). METHODS: To mimic the oxidative stress environment, SAR01/04 cells were treated with 200 µM hydrogen peroxide (H2O2) for 24 h. Cell viability and apoptosis were checked by cell counting kit-8 and flow cytometry. Western blot was taken to check the protein changes of SESN2, B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X (Bax), mechanistic target of rapamycin (mTOR), phosphorylated (p)-mTOR, ribosomal protein S6 kinase B1 (p70S6K), p-p70S6K, and nuclear factor erythroid 2-related factor 2 (Nrf2). Superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and reactive oxygen species (ROS) were detected via the corresponding reagent kit. The levels of interleukin (IL)-1ß, IL-18, and tumor necrosis factor (TNF)-α were measured using enzyme-linked immunosorbent assay. RESULTS: SESN2 was down-regulated in cataract lens tissue and up-regulated in SAR01/04 cells treated with H2O2. Under treatment of H2O2, up-regulation of SESN2 improved cell viability, enhanced the activity of SOD and CAT, inhibited cell apoptosis, and reduced the levels of MDA, ROS, IL-1ß, IL-18, and TNF-α, while down-regulation of SESN2 caused the contrary effects. Further bioinformatics analysis suggested that SESN2 regulated the mTOR signaling pathway. Treatment of H2O2 inhibited p-mTOR and p-p70S6K protein expression, while overexpression of SESN2 increased p-mTOR and p-p70S6K protein expression in the H2O2 group and down-regulation of SESN2 further decreased p-mTOR and p-p70S6K protein expression in the H2O2 group. Additionally, H2O2 increased Nrf2 protein expression, and overexpression of SESN2 further increased Nrf2 protein expression in the H2O2 group. Importantly, rapamycin (an inhibitor of mTOR signaling pathway) and knockdown of Nrf2 reversed the promotive effects of SESN2 on cell viability and the inhibitive effects of SESN2 on cell apoptosis, oxidative stress, and inflammatory reaction. CONCLUSION: SESN2 protected HLECs damage induced by H2O2, which was related to the activation of mTOR/Nrf2 pathway.

[Adipose-derived stem cell-derived exosomes regulate Th2/Treg balance in peripheral blood of AR patients through the mTOR pathway].

Objective:To investigate the mechanism of adipose derived stem cell exosomes（ADSC-exos） regulating Th2/Treg balance in peripheral blood of patients with allergic rhinitis（AR）. Methods:Thirty patients with AR who were treated in Department of Otolaryngology Head and Neck Surgery, the First Affiliated Hospital of Zhengzhou University from March 2022 to October 2022 were selected, and 30 patients with simple deviation of nasal septum who were treated in our department during the same period were selected as the control group. 10 mL peripheral venous blood was collected from all patients. The levels of IL-4 and TGF-ß in plasma were analyzed by ELISA. PBMCs were isolated by density gradient centrifugation. Then, protein and RNA were further extracted, and the expression levels of IL-4, TGF-ß, GATA3 and Foxp3 genes were detected by qRT-PCR. Western Blotting detected p-PI3K（P85）, p-AKT（Ser473） in PBMCs of AR patients and healthy controls. Protein expression levels of p-mTOR（Ser2448）, p-p70S6K（Thr389）, and the proportion of Th2 and Treg cells were analyzed by flow cytometry. PBMCs of AR patients were stimulated to differentiate and co-cultured with exosomes of adipose stem cells. p-PI3K（P85）, p-AKT（Ser473）, p-mTOR（Ser2448） were detected in exosome treated group and untreated group by Western Blotting. The expression level of p-p70S6K（Thr389） protein, the proportion of Th2 and Treg cells were analyzed by flow cytometry, and the levels of IL-4 and TGF-ß in the supernatant of cell culture were detected by ELISA. Results:Compared with the control group, the mTOR pathway in peripheral blood of AR group was significantly activated, the level of IL-4 in plasma was increased, and the level of TGF-ß was decreased（P<0.05）. Compared with the control group, the proportion of Th2 cells in peripheral blood was increased, and the proportion of Treg cells was decreased（P<0.01）. Compared with the untreated group, the expression level of mTOR pathway protein decreased, the level of IL-4 decreased, and the level of TGF-ß increased. The proportion of Th2 cells decreased, and the proportion of Treg cells increased（P<0.01）. Conclusion:There is an imbalance of Th2 and Treg cells in peripheral blood mononuclear cells of AR patients; the PI3K/AKT/mTOR/p70S6K pathway is activated in peripheral blood mononuclear cells of AR patients Exosomes derived from adipose mesenchymal stem cells may regulate Th2/Treg balance in AR patients through the PI3K/AKT/mTOR/p70S6K pathway.

[Mechanism about LMP1 of EB Virus Promoting Plasma Blast Differentiation of DLBCL Cell via mTORC1].

OBJECTIVE: To investigate possible mechanism on protien LMP1 expressed by EBV inducing plasmablast differentiation of DLBCL cell via the mTORC1 pathway. METHODS: The expression levels of LMP1 protein, CD38 and the phosphorylation levels of p70S6K in EBV+ and EBV- DLBCL cell lines were detected by Western blot. Cell lines overexpressing LMP1 gene stablely were constructed and LMP1 gene was silenced by RNAi. The expression of LMP1 gene was verified by RT-qPCR. The expression levels of LMP1 and CD38 and the phosphorylation levels of p70S6K in each group were detected by Western blot. RESULTS: Compared with EBV-DLBCL cells, the expression of LMP1 was detected on EBV +DLBCL cells (P =0.0008), EBV +DLBCL cells had higher phosphorylation levels of p70S6K (P =0.0072) and expression levels of CD38(P =0.0091). Compared with vector group, the cells of LMP1OE group had higher expression levels of LMP1 and CD38 (P =0.0353; P <0.0001), meanwhile molecular p70S6K was phosphorylated much more(P =0.0065); expression of LMP1 mRNA was verified(P <0.0001). Compared with si-NC group, expression level of LMP1 protein(P =0.0129) was not detected and phosphorylated p70S6K disappeared of LMP1KO group (P =0.0228); meanwhile, expression of CD38 decreased,although there was no significant difference (P =0.2377). CONCLUSION: LMP1 promotes DLBCL cells plasmablast differentiation via activating mTORC1 signal pathway.

Curcumin inhibits propofol-induced autophagy of MN9D cells via Akt/mTOR/p70S6K signaling pathway.

The rapid rise in propofol dependency and abuse has highlighted limited resources for addressing substance abuse-related cognitive impairment, prompting the development of novel therapies. Dysregulated autophagy flow accelerates neuronal cell death, and interventions countering this dysregulation offer an appealing strategy for neuronal protection. Curcumin, a potent natural polyphenol derived from turmeric rhizomes, is renowned for its robust antineurotoxic properties and enhanced cognitive function. Utilizing CCK-8 and Ki67 fluorescent staining, our study revealed that curcumin treatment increased cell viability and proliferative potential in MN9D cells exposed to propofol-induced neurotoxicity. Furthermore, enzyme-linked immunosorbent assay and western blot analysis demonstrated the partial restoration of dopamine synthesis, secretion levels, and TH expression in damaged MN9D cells treated with curcumin. Scanning electrode microscope images displayed reduced autolysosomes and phagosomes in curcumin-treated cells compared to the propofol group. Immunoblotting revealed that curcumin mitigated the degradation of LC3I to LC3II and p62 induced by propofol stimulation, with green fluorescence expression of LC3 postcurcumin treatment resembling that following autophagy inhibitor HCQ treatment, indicating that modulating autophagy flow can alleviate propofol's toxic effects. Moreover, curcumin treatment upregulated the Akt/mTOR/p70S6K signaling pathway, suggesting that curcumin potentially curtails autophagy dysregulation in nerve cells by activating Akt/mTOR/p70S6K. In conclusion, our findings suggest that curcumin can ameliorate propofol abuse-induced neurotoxicity, partially through autophagy regulation and Akt/mTOR/p70S6K signaling activation.

Lactate-induced autophagy activation: unraveling the therapeutic impact of high-intensity interval training on insulin resistance in type 2 diabetic rats.

Impaired autophagy is a hallmark of diabetes. The current study proposed to investigate if high intensity interval training (HIIT) induced lactate accumulation could stimulate autophagy in type 2 diabetic male rats. 28 male Wistar rats were randomly assigned into four groups: Healthy Control (CO), Diabetes Control (T2D), Exercise (EX), and Diabetes + Exercise (T2D + EX). Diabetes was induced by feeding high-fat diet and administrating single dose of streptozotocin (35 mg/kg). After becoming diabetic, the animals in the exercise groups (EX and T2D + EX) performed an eight-week HIIT (4-10 interval, 80-100% Vmax, 5 days per week). Serum levels of lactate, glucose and insulin as well as the levels of lactate, pyruvate, lactate transporter monocarboxylate transporter 1 (MCT1), phosphorylated mitogen-activated protein kinases (p-MAP 1 and 2), phosphorylated extracellular signal-regulated protein kinases 1 and 2 (p-ERK 1 and 2), mammalian target of rapamycin (p-mTOR), ribosomal protein S6 kinase beta-1 (p-70S6k), p90 ribosomal S6 kinases (p-90RSK), autophagy related 7 (ATG7), Beclin-1, microtubule-associated protein 1A/1B, and 2A/2B -light chain 3 levels (LC3-I), (LC3- II), (LC3I/LC3II) in soleus muscle were measured. Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) and serum glucose was lower in T2D + EX compared to T2D group (P < 0.0001). While serum and soleus muscle levels of lactate was not different between T2D and T2D + Ex, the levels of Pyruvate (P < 0.01), MCT1, p-ERK1/2, p-mTOR, p70S6k, P-90RSK, ATG7, LC3-II, and LC3-II/LC3I ratios were higher in T2D + EX compared to T2D group (P < 0.0001). We concluded that eight weeks of high-intensity interval training could activated ERK/P90SRK while inhibiting mTOR/P70S6K signaling pathway in lactate dependent manner. It means increased autophagy which resulted in improve insulin resistance (IR) and reduce blood glucose.

Electroacupuncture Promotes Skeletal Muscle Myogenic Differentiation and Protein Synthesis by Reducing Let-7c-5p Levels.

Objective: Acupuncture with low-frequency electrical stimulation (Acu-LFES) can attenuate muscle atrophy. Previous studies have found that Acu-LFES reduces the let-7 family in serum exosomes. This study explored the effects of let-7c-5p in chronic kidney disease (CKD) muscle atrophy. Methods: A total of 24 mice were randomly divided into control group, Acu-LFES group, CKD group, and CKD/Acu-LFES group (n = 6/group). The 5/6 nephrectomy was performed to establish the CKD model in mice. After 20 weeks, the Acu-LFES group and CKD/Acu-LFES group were treated with electroacupuncture at the "Zu San Li" and "Yang Ling Quan" bilaterally points for 15 minutes once. Surface sensing of translation (SUnSET), Reverse Transcription-quantitative PCR(RT-qPCR), immunofluorescence staining, and Western blot were performed to examine each group's state of protein production and myogenic differentiation. we knocked down or exogenously expressed let-7c-5p in C2C12 myoblast, RT-qPCR, and Western blot were performed to examine protein synthesis and myogenic differentiation. Results: The protein expressions of MyoD and Myogenin (MyoG) were decreased in the CKD group (P = .029 and P = .026) concomitant with a decrease in the muscle fiber cross-sectional area. Acu-LFES prevented muscle atrophy in CKD mice. The protein expressions of MyoD and MyoG were increased in the CKD/Acu-LFES group (P = .006 and P = .001). In muscle of CKD mice, IGF1, IGF1R, IRS1, phosphorylated mTOR and P70S6K proteins were decreased compared with control muscle (P = .001, P = .007, P < .001, P < .001 and P < .001), whereas atrogin-1/MAFbx and MuRF1 were dramatically increased (P < .001). Acu-LFES reversed these phenomena, indicating IGF1/mTOR signaling pathway was induced to promote muscle protein synthesis and myogenic differentiation. Meanwhile, Acu-LFES caused a decrease of let-7c-5p in skeletal muscle of CKD mice (P = .034). Inhibiting let-7c-5p promoted C2C12 myogenic differentiation (P = .002 and P = .001) and increased IGF1, IGF1R, IRS1 levels while upregulating mTOR and P70S6K phosphorylation (P < .001, P = .002, P = .009, P < .001 and P = .007). It is interesting to observe that the abundance of atrogin-1/MAFbx and MuRF-1 was unaffected by let-7c-5p (P > .05). Conclusions: Acu-LFES-reduced expression of let-7c-5p can ameliorate CKD-induced skeletal muscle atrophy by upregulating the IGF1/mTOR signaling pathway, which enhances skeletal muscle protein synthesis and myogenic differentiation. Let-7c-5p may be a potential regulator for the treatment of muscle atrophy.

PP2A inhibitor SET promotes mTORC1 and Bmi1 signaling through Akt activation and maintains the colony-formation ability of cancer cells.

Protein phosphatase 2A (PP2A) is an essential tumor suppressor, with its activity often hindered in cancer cells by endogenous PP2A inhibitory proteins like SE translocation (SET). SET/PP2A axis plays a pivotal role in the colony-formation ability of cancer cells and the stabilization of c-Myc and E2F1 proteins implicated in this process. However, in osteosarcoma cell line HOS, SET knock-down (KD) suppresses the colony-formation ability without affecting c-Myc and E2F1. This study aimed to unravel the molecular mechanism through which SET enhances the colony-formation ability of HOS cells and determine if it is generalized to other cancer cells. Transcriptome analysis unveiled that SET KD suppressed mTORC1 signaling. SET KD inhibited Akt phosphorylation, an upstream kinase for mTORC1. PP2A inhibitor blocked SET KD-mediated decrease in phosphorylation of Akt and a mTORC1 substrate p70S6K. A constitutively active Akt restored decreased colony-formation ability by SET KD, indicating the SET/PP2A/Akt/mTORC1 axis. Additionally, enrichment analysis highlighted that Bmi-1, a polycomb group protein, is affected by SET KD. SET KD decreased Bmi-1 protein by Akt inhibition but not by mTORC1 inhibition, and exogenous Bmi-1 expression rescued the reduced colony formation by SET KD. Four out of eight cancer cell lines exhibited decreased Bmi-1 by SET KD. Further analysis of these cell lines revealed that Myc activity plays a role in SET KD-mediated Bmi-1 degradation. These findings provide new insights into the molecular mechanism of SET-regulated colony-formation ability, which involved Akt-mediated activation of mTORC1/p70S6K and Bmi-1 signaling.

Chronic mild stress leads to anxiety-like behavior and decreased p70 S6K1 activity in the hippocampus of male mice.

Major affective disorders are highly prevalent, however, current treatments are limited in their effectiveness due to a lack of understanding of underlying molecular mechanisms. Recent studies have shown that reduced activity of p70 S6 kinase 1 (S6K1), a downstream target of the mechanistic target of rapamycin complex 1 (mTORC1), is linked to anxiety-like behavior in both humans and rodents. The purpose of this study was to investigate the relationship between S6K1 and anxiety-like behavior following chronic mild stress (CMS) and drug-induced inhibition of S6K1. Following CMS, anxiety-like behavior was evaluated using an open field (OF) and elevated plus maze (EPM) in adult male C57/Bl6 mice. After behavior analysis, samples of the hippocampus were harvested for quantification of S6K1, S6 ribosomal protein, glycogen synthase kinase-3 ß (GSK3ß), and beta tubulin via western blot. Our results demonstrate that CMS mice exhibit anxiety-like behavior in the OF and EPM and reduced activity of S6K1 in the hippocampus (HPC). We measured phosphorylation levels of GSK3ß and found that GSK3ß phosphorylation was also reduced following CMS compared to control mice. Furthermore, pharmacological inhibition of S6K1 with PF-4708671 in male mice was sufficient to produce anxiety-like behavior in the OF and EPM. These results further support the significant role of S6K1 in the pathogenesis of anxiety and affective disorders.

Changes in Skeletal Muscle Protein Metabolism Signaling Induced by Glutamine Supplementation and Exercise.

AIM: To evaluate the effects of resistance exercise training (RET) and/or glutamine supplementation (GS) on signaling protein synthesis in adult rat skeletal muscles. METHODS: The following groups were studied: (1) control, no exercise (C); (2) exercise, hypertrophy resistance exercise training protocol (T); (3) no exercise, supplemented with glutamine (G); and (4) exercise and supplemented with glutamine (GT). The rats performed hypertrophic training, climbing a vertical ladder with a height of 1.1 m at an 80° incline relative to the horizontal with extra weights tied to their tails. The RET was performed three days a week for five weeks. Each training session consisted of six ladder climbs. The extra weight load was progressively increased for each animal during each training session. The G groups received daily L-glutamine by gavage (one g per kilogram of body weight per day) for five weeks. The C group received the same volume of water during the same period. The rats were euthanized, and the extensor digitorum longus (EDL) muscles from both hind limbs were removed and immediately weighed. Glutamine and glutamate concentrations were measured, and histological, signaling protein contents, and mRNA expression analyses were performed. RESULTS: Supplementation with free L-glutamine increased the glutamine concentration in the EDL muscle in the C group. The glutamate concentration was augmented in the EDL muscles from T rats. The EDL muscle mass did not change, but a significant rise was reported in the cross-sectional area (CSA) of the fibers in the three experimental groups. The levels of the phosphorylated proteins (pAkt/Akt, pp70S6K/p70S6K, p4E-BP1/4E-BP1, and pS6/S6 ratios) were significantly increased in EDL muscles of G rats, and the activation of p4E-BP1 was present in T rats. The fiber CSAs of the EDL muscles in T, G, and GT rats were increased compared to the C group. These changes were accompanied by a reduction in the 26 proteasome activity of EDL muscles from T rats. CONCLUSION: Five weeks of GS and/or RET induced muscle hypertrophy, as indicated by the increased CSAs of the EDL muscle fibers. The increase in CSA was mediated via the upregulated phosphorylation of Akt, 4E-BP1, p70S6k, and S6 in G animals and 4E-BP1 in T animals. In the EDL muscles from T animals, a decrease in proteasome activity, favoring a further increase in the CSA of the muscle fibers, was reported.