Mammalian Target Of Rapamycin Complex Research Articles

MTORC1 phosphorylates and stabilizes LST2 to negatively regulate EGFR

TORC1 (target of rapamycin complex 1) is a highly conserved protein kinase that plays a central role in regulating cell growth. Given the role of mammalian TORC1 (mTORC1) in metabolism and disease, understanding mTORC1 downstream signaling and feedback loops is important. mTORC1 recognizes some of its substrates via a five amino acid binding sequence called the TOR signaling (TOS) motif. mTORC1 binding to a TOS motif facilitates phosphorylation of a distinct, distal site. Here, we show that LST2, also known as ZFYVE28, contains a TOS motif (amino acids 401 to 405) and is directly phosphorylated by mTORC1 at serine 670 (S670). mTORC1-mediated S670 phosphorylation promotes LST2 monoubiquitination on lysine 87 (K87). Monoubiquitinated LST2 is stable and displays a broad reticular distribution. When mTORC1 is inactive, unphosphorylated LST2 is degraded by the proteasome. The absence of LST2 enhances EGFR (epidermal growth factor receptor) signaling. We propose that mTORC1 negatively feeds back on its upstream receptor EGFR via LST2.

Insulin restores retinal ganglion cell functional connectivity and promotes visual recovery in glaucoma.

Dendrite pathology and synaptic loss result in neural circuit dysfunction, a common feature of neurodegenerative diseases. There is a lack of strategies that target dendritic and synaptic regeneration to promote neurorecovery. We show that daily human recombinant insulin eye drops stimulate retinal ganglion cell (RGC) dendrite and synapse regeneration during ocular hypertension, a risk factor to develop glaucoma. We demonstrate that the ribosomal protein p70S6 kinase (S6K) is essential for insulin-dependent dendritic regrowth. Furthermore, S6K phosphorylation of the stress-activated protein kinase-interacting protein 1 (SIN1), a link between the mammalian target of rapamycin complexes 1 and 2 (mTORC1/2), is required for insulin-induced dendritic regeneration. Using two-photon microscopy live retinal imaging, we show that insulin rescues single-RGC light-evoked calcium (Ca2+) dynamics. We further demonstrate that insulin enhances neuronal survival and retina-brain connectivity leading to improved optomotor reflex-elicited behaviors. Our data support that insulin is a compelling pro-regenerative strategy with potential clinical implications for the treatment and management of glaucoma.

MTORC1 Signaling Inhibition Modulates Mitochondrial Function in Frataxin Deficiency.

Lysosomes regulate mitochondrial function through multiple mechanisms including the master regulator, mechanistic Target of Rapamycin Complex 1 (mTORC1) protein kinase, which is activated at the lysosomal membrane by nutrient, growth factor and energy signals. mTORC1 promotes mitochondrial protein composition changes, respiratory capacity, and dynamics, though the full range of mitochondrial-regulating functions of this protein kinase remain undetermined. We find that acute chemical modulation of mTORC1 signaling decreased mitochondrial oxygen consumption, increased mitochondrial membrane potential and reduced susceptibility to stress-induced mitophagy. In cellular models of Friedreich's Ataxia (FA), where loss of the Frataxin (FXN) protein suppresses Fe-S cluster synthesis and mitochondrial respiration, the changes induced by mTORC1 inhibitors lead to improved cell survival. Proteomic-based profiling uncover compositional changes that could underlie mTORC1-dependent modulation of FXN-deficient mitochondria. These studies highlight mTORC1 signaling as a regulator of mitochondrial composition and function, prompting further evaluation of this pathway in the context of mitochondrial disease.

21 Unconventional mechanisms of action and resistance to rapalogs in renal cancer

Abstract Background Clear cell renal cell carcinoma (ccRCC) is a prevalent cancer type in the United States driven by inactivation of the von Hippel-Lindau (VHL) gene and with frequent hyperactivation of mammalian target of rapamycin complex 1 (mTORC1). Multiple drugs have been developed to target VEGF/VEGFR2 and mTORC1 for advanced RCC treatment. Two specific mTORC1 inhibitors, temsirolimus and everolimus (known as rapalogs), are FDA-approved for the treatment of RCC but their clinical efficacy is hindered by the emergence of resistance. Methods To study the development of rapalog resistance in RCC, we utilized patient-derived tumorgrafts (TGs) implanted in immunocompromised mice and treated the mice with rapamycin for prolonged periods to generate resistance. Resistance was studied by transplanting resistant tumors into additional cohorts of mice and establishing primary cultures. The impact of rapamycin on tumor growth and mTORC1 activity in both tumor and stromal cells was assessed using molecular techniques. To dissect the role of the tumor microenvironment (TME), we generated genetically engineered immunocompromised recipient mice with an mTOR inhibitor resistance mutation (S2035T). Coculture experiments were performed to further explore the interplay. Results Prolonged rapamycin treatment resulted in the development of resistance in TGs. Notably, this occurred despite persistent inhibition of mTORC1 in tumor cells. Resistance was transient and lost with subsequent transplantation and in cell culture. Surprisingly, resistance was accompanied by mTORC1 reactivation in the TME, specifically in cancer associated fibroblasts. Introducing an mTOR resistance mutation (S2035T) into recipient mice was sufficient to cause resistance. Co-culture experiments with fibroblasts further demonstrated that rapamycin-resistant mutant fibroblasts conferred resistance in tumor cells even in the absence of mTORC1 activity. Conclusions This study uncovers a critical role of the TME, in mediating the response and resistance to rapalogs in RCC. Our data show that inhibition of mTORC1 in non-tumor cells is essential for the anti-tumor activity of rapalogs. These findings shed light on why mTOR mutations are rarely observed in resistant RCC patients and highlight the significance of the TME in modulating drug response and resistance. Moreover, our study emphasizes the potential of targeting TME cells as a therapeutic strategy in RCC and possibly other cancers. DOD CDMRP Funding: yes

Targeting mechanistic target of rapamycin complex 2 attenuates immunopathology in Systemic Lupus Erythematosus.

We aim to explore the role of mechanistic target of rapamycin complex (mTORC) 2 in systemic lupus erythematosus (SLE) development, the in vivo regulation of mTORC2 by type I interferon (IFN) signaling in autoimmunity, and to use mTORC2 targeting therapy to ameliorate lupus-like symptoms in an in vivo lupus mouse model and an in vitro coculture model using human PBMCs. We first induced lupus-like disease in T cell specific Rictor, a key component of mTORC2, deficient mice by topical application of imiquimod (IMQ) and monitored disease development. Next, we investigated the changes of mTORC2 signaling and immunological phenotypes in type I IFNAR deficient Lpr mice. We then tested the beneficial effects of anti-Rictor antisense oligonucleotide (Rictor-ASO) in a mouse model of lupus: MRL/lpr mice. Finally, we examined the beneficial effects of RICTOR-ASO on SLE patients' PBMCs using an in vitro T-B cell coculture assay. T cell specific Rictor deficient mice have reduced age-associated B cells, plasma cells and germinal center B cells, and less autoantibody production than WT mice following IMQ treatment. IFNAR1 deficient Lpr mice have reduced mTORC2 activity in CD4+ T cells accompanied by restored CD4+ T cell glucose metabolism, partially recovered T cell trafficking, and reduced systemic inflammation. In vivo Rictor-ASO treatment improves renal function and pathology in MRL/lpr mice, along with improved immunopathology. In human SLE (N = 5) PBMCs derived T-B coculture assay, RICTOR-ASO significantly reduce immunoglobulin and autoantibodies production (P < 0.05). Targeting mTORC2 could be a promising therapeutic for SLE.

Lysosomal Storage Diseases: Natural Products Inducing Autophagy

Background: The link between autophagy and lysosomal function has been wellrecognised in recent decades; defective autophagy and lysosomal function lead to various disorders, notably Lysosomal Storage Disorders (LSDs). The malfunction of multiple mechanistic pathways influences the contribution of LSDs. Different ways are employed in such situations, but one novel approach could resolve the problem by inducing the autophagic pathway, which aids in maintaining proper autophagy and lysosomal degradation function. Methods: Autophagic Inducer functions on the activation of Transcriptional factor EB (TFEB) and its mechanism; mTOR Complex Inhibition dependently or independently may repair the malfunction of the entire mechanism. Finding a potential autophagic inducer is still a work in progress, but targeting TFEB and mTOR could redefine LSD treatment. The development of experimentally available TFEB modulators could enhance autophagic flux promote lysosomal function and increase lysosomal biogenesis and can be a promising technique for treating illnesses caused by ALP dysfunction, such as lysosomal storage disorder. Results: MTORC1 suppression causes TFEB to be transported to the nucleus and transcription of multiple genes involved in the formation of autophagosomes and lysosomes, indicating that MTORC1 has positive effects in treating lysosomal storage diseases such as Pompe disease, Batton disease, Fabry disease, etc. thus modulating autophagy attenuates the above condition. Conclusion: This review comprises autophagy and lysosome association, and their malfunction leads to various lysosomal diseases. Several natural products are also discussed, which can be possible treatment options.

MTORC2 knockdown mediates lipid metabolism to alleviate hyperlipidemic pancreatitis through PPARα.

Hyperlipidemic pancreatitis (HP) is an inflammatory injury of the pancreas triggered by elevated serum triglyceride (TG) levels. The mechanistic target of rapamycin (mTOR) signaling pathway plays a crucial role in regulating lipid homeostasis and inflammation. This study aimed to investigate whether the activity of mTOR complex 2 (mTORC2) affects the progression of HP and its underlying mechanisms. In vivo, a high-fat diet and retrograde administration of sodium taurocholate were employed to establish theHP models in rats, with pancreatic tissue pathology evaluated. The expression of Rictor and peroxisome proliferator-activator receptor (PPAR) was examined. The serum levels of TG, fatty acid metabolites, inflammatory and lipid metabolism-related factors were determined. In vitro, pancreatic acinar cells (PACs) were exposed to palmitic acid and cholecystokinin-8. PAC apoptosis, pyroptosis, and ferroptosis were assessed. In the HP models, rats and PACs exhibited upregulated Rictor and downregulated PPARα, and Rictor knockdown promoted PPARα expression. In vivo, Rictor knockdown decreased the serum levels of TG, α-amylase, total cholesterol, low-density lipoprotein cholesterol, lactate dehydrogenase, and inflammatory factors, while increasing high-density lipoprotein cholesterol levels. Rictor knockdown increased ACOX1 and CPT1α and decreased SREBP-1, CD36, SCD1, ACLY, and ACACA. Rictor knockdown reduced damage to pancreatic tissue structure. In vitro, Rictor knockdown inhibited PAC apoptosis, pyroptosis, and ferroptosis. Treatment with the PPARα antagonist GW6471 abolished the beneficial effects of Rictor knockdown. Rictor/mTORC2 deficiency reduces serum TG levels, maintains lipid homeostasis, and suppresses inflammation by inhibiting PPARα expression. Weakening mTORC2 activity holds promise as a novel therapeutic strategy for HP.

Neohesperidin exerts antidepressant-like effect via the mechanistic target of rapamycin complex 1 in the medial prefrontal cortex in male mice

Neohesperidin, a citrus flavonoid, shows potential for activating the mechanistic target of rapamycin complex 1 (mTORC1). Here, the antidepressant-like effect of neohesperidin was examined in male ICR mice (naïve mice and mice treated repeatedly with prednisolone, a synthetic glucocorticoid, which induces depression-like behavior). Oral neohesperidin administration exerted an antidepressant-like effect in the forced swim test 1 h post-treatment, in naïve mice; this effect was no longer observed at 24 h. Neohesperidin also reversed prednisolone-induced depression-like behavior. This effect was blocked by infusing rapamycin, an mTORC1 inhibitor, into the medial prefrontal cortex. Neohesperidin may rapidly produce an antidepressant-like effect.

Metabolic determinants of germinal center B cell formation and responses.

Germinal center (GC) B cells are crucial for the generation of GCs and long-lived humoral immunity. Here we report that one-carbon metabolism determines the formation and responses of GC B cells. Upon CD40 stimulation, GC B cells selectively upregulate methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) expression to generate purines and the antioxidant glutathione. MTHFD2 depletion reduces GC B cell frequency and antigen-specific antibody production. Moreover, supplementation with nucleotides and antioxidants suffices to promote GC B cell formation and function in vitro and in vivo through activation of the mammalian target of rapamycin complex 1 signaling pathway. Moreover, we found that antigen stimulation enhances YY1 binding to the Mthfd2 promoter and promotes MTHFD2 transcription. Interestingly, these findings can be generalized to the pentose phosphate pathway, which is another major source of reducing power and nucleotides. Therefore, these results suggest that an increased capacity for nucleotide synthesis and redox balance is required for GC B cell formation and responses, revealing a key aspect of GC B cell fate determination.

MTORC1 activity oscillates throughout the cell cycle, promoting mitotic entry and differentially influencing autophagy induction

Mechanistic Target of Rapamycin Complex 1 (mTORC1) is a master metabolic regulator that is active in nearly all proliferating eukaryotic cells; however, it is unclear whether mTORC1 activity changes throughout the cell cycle. We find that mTORC1 activity oscillates from lowest in mitosis/G1 to highest in S/G2. The interphase oscillation is mediated through the TSC complex but is independent of major known regulatory inputs, including Akt and Mek/Erk signaling. By contrast, suppression of mTORC1 activity in mitosis does not require the TSC complex. mTORC1 has long been known to promote progression through G1. We find that mTORC1 also promotes progression through S and G2 and is important for satisfying the Chk1/Wee1-dependent G2/M checkpoint to allow entry into mitosis. We also find that low mTORC1 activity in G1 sensitizes cells to autophagy induction in response to partial mTORC1 inhibition or reduced nutrient levels. Together, these findings demonstrate that mTORC1 is differentially regulated throughout the cell cycle, with important phase-specific consequences for proliferating cells.

MTORC1 activation in presumed classical monocytes: observed correlation with human size variation and neuropsychiatric disease.

Gain of function disturbances in nutrient sensing are likely the largest component in human age-related disease. Mammalian target of rapamycin complex 1 (mTORC1) activity affects health span and longevity. The drugs ketamine and rapamycin are effective against chronic pain and depression, and both affect mTORC1 activity. Our objective was to measure phosphorylated p70S6K, a marker for mTORC1 activity, in individuals with psychiatric disease to determine whether phosphorylated p70S6K could predict medication response. Twenty-seven females provided blood samples in which p70S6K and phosphorylated p70S6K were analyzed. Chart review gathered biometric measurements, clinical phenotypes, and medication response. Questionnaires assessed anxiety, depression, autism traits, and mitochondrial dysfunction, to determine neuropsychiatric disease profiles. Univariate and multivariate statistical analyses were used to identify predictors of medication response. mTORC1 activity correlated highly with both classical biometrics (height, macrocephaly, pupil distance) and specific neuropsychiatric disease profiles (anxiety and autism). Across all cases, phosphorylated p70S6K was the best predictor for ketamine response, and also the best predictor for rapamycin response in a single instance. The data illustrate the importance of mTORC1 activity in both observable body structure and medication response. This report suggests that a simple assay may allow cost-effective prediction of medication response.

PMEL is a predictive biomarker for mTORC1 inhibitor treatment of renal angiomyolipoma in tuberous sclerosis complex patients

BackgroundWe aimed to demonstrate the function of premelanosome protein (PMEL) as a biomarker to predict the effectiveness of mammalian target of rapamycin complex 1 (mTORC1) inhibitor treatment in renal angiomyolipomas (RAMLs) in tuberous sclerosis complex (TSC) patients. Methods95 whole blood samples from 49 patients diagnosed with TSC-RAMLs were collected. PMEL, N4BP2, and PCSK1N expression in the plasma samples were tested by quantitative sandwich ELISA. The target tumor volume assessed by maximum cross-sectional area (CSAmax) in CT scans. Correlation analysis was used to determine the relationship between PMEL expression and target tumors, as well as the tumor reduction rate. ResultsThe tumor size of TSC-RAMLs positivity correlated with PMEL expression (r = 0.30, p = 0.036) and PCSK1N expression (r = 0.23, p = 0.027), but had no significant relationship with N4BP2 (r = 0.06, p = 0.89). The positive correlation between TSC-RAML tumor volume and PMEL expression still existed in TSC patients before (r = 0.30, p = 0.026) and after mTORC1 inhibitor treatment (r = 0.41, p = 0.0017), but the correlation between tumor volume and PCSK1N expression no longer existed. Further analysis found that PMEL expression negatively correlated with the reduction rate of TSC-RAMLs after mTORC1 inhibitor treatment (r = −0.50, p = 0.0022), both after 3 months (r = −0.47, p = 0.048) and 6 months of treatment (r = −0.52, p = 0.028). ConclusionPMEL expression positively correlated with the tumor size of TSC-RAMLs, and inversely with the reduction rate of TSC-RAMLs after mTORC1 inhibitor treatment, which may suggest that PMEL may serve as a predictive biomarker for the efficacy of mTORC1 inhibitor treatment.

Cytoplasmic vacuolization and ectopic formation of perineuronal nets are characteristic pathologies of cytomegalic neurons in tuberous sclerosis.

Cytomegalic neurons, characterized by increased size and a hyperactive mechanistic target of rapamycin complex 1 (mTORC1), are pathognomonic for tuberous sclerosis complex (TSC). To model these neurons, we recently generated a murine Tsc1 conditional knockout model in which Tsc1 deletion in late embryonic radial glia results in neuronal hypertrophy of a subset of isocortical pyramidal neurons. In the current study, we compared the cellular pathology of these cytomegalic neurons to those of the enlarged neurons in human cortical tubers. Neurons from the mice showed unique features, such as cytoplasmic vacuoles associated with Golgi complexes and the ectopic formation of perineuronal nets (PNNs), a feature of inhibitory neurons, rarely present in excitatory cortical neurons. The membranes of these vacuoles were enriched for the plasma membrane proteins CD44, KCC2, and Na+/K+ ATPase, suggesting deficits in Golgi membrane trafficking. These aberrant features in the mouse appeared only after the onset of seizures, probably due to the prolonged seizure activity in the context of constitutive mTORC1 activation. Similar PNNs and cytoplasmic vacuoles were present in the cytomegalic neurons of human cortical tubers. Our findings reveal novel pathological features of Golgi complexes and PNNs in the cytomegalic neurons in TSC.

Peripheral blood MR1 tetramer-positive mucosal-associated invariant T-cell function is modulated by mammalian target of rapamycin complex 1 in patients with active tuberculosis.

Tuberculosis (TB) is still an urgent global public health problem. Notably, mucosal-associated invariant T (MAIT) cells play an important role in early anti-TB immune response. Targeted control of them may be an effective method to improve vaccine efficacy and TB treatment. However, the biology and signal regulation mechanisms of MAIT cells in TB patients are still poorly understood. Previous studies have been limited by the lack of reagents to specifically identify MAIT cells. In addition, the use of alternative markers may subsume non-MAIT cell into MAIT cell populations. In this study, the human MR1 tetramer which can specifically identify MAIT cells was used to further explore the effect and mechanism of MAIT cells in anti-TB immune response. Our results showed that the tetramer+ MAIT cells in peripheral blood of TB patients were mainly CD8+ or CD4-CD8- cells, and very few were CD4+ cells. After BCG infecting autologous antigen-presenting cells, MAIT cells in patients produced significantly higher levels of cytokines, lysis and proliferation compared with healthy controls. After suppression of mTORC1 by the mTORC1-specific inhibitor rapamycin, the immune response of MAIT cells in patients was significantly reduced. This study demonstrates that peripheral blood tetramer+ MAIT cells from TB patients have significant anti-TB immune effect, which is regulated by mTORC1. This could provide ideas and potential therapeutic targets for the development of novel anti-TB immunotherapy.

The Spectrum of Renal "TFEopathies": Flipping the mTOR Switch in Renal Tumorigenesis.

The mammalian target of Rapamycin complex 1 (mTORC1) is a serine/threonine kinase that couples nutrient and growth factor signaling to the cellular control of metabolism and plays a fundamental role in aberrant proliferation in cancer. mTORC1 has previously been considered an "on/off" switch, capable of phosphorylating the entire pool of its substrates when activated. However, recent studies have indicated that mTORC1 may be active toward its canonical substrates, eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) and S6 kinase (S6K), involved in mRNA translation and protein synthesis, and inactive toward TFEB and TFE3, transcription factors involved in the regulation of lysosome biogenesis, in several pathological contexts. Among these conditions are Birt-Hogg-Dubé syndrome (BHD) and, recently, tuberous sclerosis complex (TSC). Furthermore, increased TFEB and TFE3 nuclear localization in these syndromes, and in translocation renal cell carcinomas (tRCC), drives mTORC1 activity toward the canonical substrates, through the transcriptional activation of the Rag GTPases, thereby positioning TFEB and TFE3 upstream of mTORC1 activity toward 4EBP1 and S6K. The expanding importance of TFEB and TFE3 in the pathogenesis of these renal diseases warrants a novel clinical grouping that we term "TFEopathies." Currently, there are no therapeutic options directly targeting TFEB and TFE3, which represents a challenging and critically required avenue for cancer research.

Cancer Cell Secreted Legumain Promotes Gastric Cancer Resistance to Anti-PD-1 Immunotherapy by Enhancing Macrophage M2 Polarization.

The interaction between cancer cells and immune cells plays critical roles in gastric cancer (GC) progression and immune evasion. Forced legumain (LGMN) is one of the characteristics correlated with poor prognosis in gastric cancer patients. However, the role of gastric-cancer-secreted LGMN (sLGMN) in modulating the tumor immune microenvironment and the biological effect on the immune evasion of gastric cancer remains unclear. In this study, we found that forced expression of sLGMN in gastric cancer serum correlates with increased M2 macrophage infiltration in GC tissues and predicted resistance to anti-PD-1 immunotherapy. Mechanistically, gastric cancer cells secrete LGMN via binding to cell surface Integrin αvβ3, then activate Integrin αvβ3/PI3K (Phosphatidylinositol-4,5-bisphosphate3-kinase)/AKT (serine/threonine kinase)/mTORC2 (mammalian target of rapamycin complex 2) signaling, promote metabolic reprogramming, and polarize macrophages from the M1 to the M2 phenotype. Either blocking LGMN, Integrin αv, or knocking out Integrin αv expression and abolishing the LGMN/Integrin αvβ3 interaction significantly inhibits metabolic reprogramming and polarizes macrophages from the M1 to the M2 phenotype. This study reveals a critical molecular crosstalk between gastric cancer cells and macrophages through the sLGMN/Integrinαvβ3/PI3K/AKT/mTORC2 axis in promoting gastric cancer immune evasion and resistance to anti-PD-1 immunotherapy, indicating that the sLGMN/Integrinαvβ3/PI3K/AKT/mTORC2 axis may act as a promising therapeutic target.

A review on macrocyclic kinase inhibitors in clinical trials

Macrocyclic kinase inhibitors have high binding affinity and selectivity towards a variety of kinases including mammalian target of rapamycin complex 1/2, janus kinases/ Fms like tyrosine kinase, cyclin-dependent kinases and anaplastic lymphoma kinase1. Recently, few macrocyclic kinase inhibitors have entered clinical trial for treatment different types of cancers including leukemia, non-small cell lung cancer, myelofibrosis, breast cancer, glioblastoma and lymphoma. Of them, ridaforomilus has completed Phase III clinical trial and is waiting to be approved for treatment of breast cancer and advanced leukemia. Pacritinib is also currently being tested in phase III clinical trial for treatment of myelofibrosis and, loratinib is being evaluated for advanced ALK gene positive nonsmall cell lung carcinoma. The broad-spectrum cyclin-dependent kinases inhibitor, TGO2, has also entered phase II clinical trial for treatment of glioblastoma and advanced leukemia.

Glycolysis-related five-gene signature correlates with prognosis and immune infiltration in gastric cancer.

Gastric cancer (GC) is one of the most common malignancies worldwide. Glycolysis has been demonstrated to be pivotal for the carcinogenesis of GC. To develop a glycolysis-based gene signature for prognostic evaluation in GC patients. Differentially expressed genes correlated with glycolysis were identified in stomach adenocarcinoma data (STAD). A risk score was established through a univariate Cox and least absolute shrinkage and selection operator analysis. The model was evaluated using the area under the receiver operating characteristic curves. RNA-sequencing data from high- and low-glycolysis groups of STAD patients were analyzed using Cibersort algorithm and Spearman correlation to analyze the interaction of immune cell infiltration and glycolysis. Multiomics characteristics in different glycolysis status were also analyzed. A five-gene signature comprising syndecan 2, versican, malic enzyme 1, pyruvate carboxylase and SRY-box transcription factor 9 was constructed. Patients were separated to high- or low-glycolysis groups according to risk scores. Overall survival of patients with high glycolysis was poorer. The sensitivity and specificity of the model in prediction of survival of GC patients were also observed by receiver operating characteristic curves. A nomogram including clinicopathological characteristics and the risk score also showed good prediction for 3- and 5-year overall survival. Gene set variation analysis showed that high-glycolysis patients were related to dysregulation of pancreas beta cells and estrogen late pathways, and low-glycolysis patients were related to Myc targets, oxidative phosphorylation, mechanistic target of rapamycin complex 1 signaling and G2M checkpoint pathways. Tumor-infiltrating immune cells and multiomics analysis suggested that the different glycolysis status was significantly correlated with multiple immune cell infiltration. The patients with high glycolysis had lower tumor mutational burden and neoantigen load, higher incidence of microsatellite instability and lower chemosensitivity. High glycolysis status was often found among patients with grade 2/3 cancer or poor prognosis. The genetic characteristics revealed by glycolysis could predict the prognosis of GC. High glycolysis significantly affects GC phenotype, but the detailed mechanism needs to be further studied.

MTORC2: A neglected player in aging regulation.

Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that plays a pivotal role in various biological processes, through integrating external and internal signals, facilitating gene transcription and protein translation, as well as by regulating mitochondria and autophagy functions. mTOR kinase operates within two distinct protein complexes known as mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), which engage separate downstream signaling pathways impacting diverse cellular processes. Although mTORC1 has been extensively studied as a pro-proliferative factor and a pro-aging hub if activated aberrantly, mTORC2 received less attention, particularly regarding its implication in aging regulation. However, recent studies brought increasing evidence or clues for us, which implies the associations of mTORC2 with aging, as the genetic elimination of unique subunits of mTORC2, such as RICTOR, has been shown to alleviate aging progression in comparison to mTORC1 inhibition. In this review, we first summarized the basic characteristics of mTORC2, including its protein architecture and signaling network. We then focused on reviewing the molecular signaling regulation of mTORC2 in cellular senescence and organismal aging, and proposed the multifaceted regulatory characteristics under senescent and nonsenescent contexts. Next, we outlined the research progress of mTOR inhibitors in the field of antiaging and discussed future prospects and challenges. It is our pleasure if this review article could provide meaningful information for our readers and call forth more investigations working on this topic.

Ribosomal Protein Dynamics and Its Association with Actin Filaments and Local Translation in Axonal Growth Cones of Dorsal Root Ganglia Neurons.

Local translation in growth cones plays a critical role in responses to extracellular stimuli, such as axon guidance cues. We previously showed that brain-derived neurotrophic factor activates translation and enhances novel protein synthesis through the activation of mammalian target of rapamycin complex 1 signaling in growth cones of dorsal root ganglion neurons. In this study, we focused on 40S ribosomal protein S6 (RPS6), 60S ribosomal protein P0/1/2 (RPP0/1/2), and actin filaments to determine how localization of ribosomal proteins changes with overall protein synthesis induced by neurotrophins. Our quantitative analysis using immunocytochemistry and super-resolution microscopy indicated that RPS6, RPP0/1/2, and actin tend to colocalize in the absence of stimulation, and that these ribosomal proteins tend to dissociate from actin and associate with each other when local protein synthesis is enhanced. We propose that this is because stimulation causes ribosomal subunits to associate with each other to form actively translating ribosomes (polysomes). This study further clarifies the role of cytoskeletal components in local translation in growth cones.