Bone Morphogenetic Protein 2 Enhances Porcine Beige Adipogenesis via AKT/mTOR and MAPK Signaling Pathways

Bone morphogenetic protein 2 (BMP2) has been reported to regulate adipogenesis, but its role in porcine beige adipocyte formation remains unclear. Our data reveal that BMP2 is significantly induced at the early stages of porcine beige adipocyte differentiation. Additionally, supplementing rhBMP2 during the early stages, but not the late stages of differentiation, significantly enhances porcine SVF adipogenesis, thermogenesis, and proliferation. Furthermore, compared to the empty plasmid-transfected-SVFs, BMP2-overexpressed SVFs had the enhanced lipid accumulation and thermogenesis, while knockdown of BMP2 in SVFs exhibited the opposite effect. The RNA-seq of the above three types of cells revealed the enrichment of the annotation of thermogenesis, brown cell differentiation, etc. In addition, the analysis also highlights the significant enrichment of cell adhesion, the MAPK cascade, and PPARγ signaling. Mechanistically, BMP2 positively regulates the adipogenic and thermogenic capacities of porcine beige adipocytes by activating PPARγ expression through AKT/mTOR and MAPK signaling pathways.

Moxibustion preconditioning reduces inflammatory response in rats with cerebral ischemia-reperfusion injury by regulating PI3K / AKT / mTOR signaling pathway

OBJECTIVES

To observe the effect of moxibustion preconditioning on inflammatory response in rats with cerebral ischemia reperfusion injury (CIRI), so as to explore its mechanisms underlying improving CIRI.

METHODS

Seventy-five male SD rats were randomly divided into sham operation, model, moxibustion preconditioning 3 days (Moxi 1), moxibustion preconditioning 5 days (Moxi 2) and moxibustion preconditioning 7 days (Moxi 3) groups, with 15 rats in each group. Moxibustion was applied at "Baihui"(GV20), "Dazhui"(GV14) and "Zusanli"(ST36) for 20 min once a day, totally for 3, 5 or 7 days. Thirty minutes after the last moxibustion treatment, the CIRI model was established by occlusion of the middle cerebral artery. The neurological deficit score was assessed by using Longa's method. The infarct size of the brain assessed after staining with 2% triphenyltetrazolium chloride (TTC). The morphological changes of cortical neurons were observed by HE staining. The contents of inflammatory factors interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), S-100β protein (S-100β) and neuron-specific enolase (NSE) were detected by ELISA. The expression of phosphatidylinositol-3-kinase (PI3K), p-PI3K, protein kinase B (AKT) and mammalian target of rapamycin (mTOR) proteins in the ischemic cortex tissues were detected by immunohistochemistry and Western blot.

RESULTS

Compared with the sham operation group, the neurological function score and the percentage of cerebral ischemic volume were increased (P<0.01). The contents of serum IL-1β, TNF-α, S-100β and NSE were significantly increased (P<0.01), while the protein expressions of PI3K, p-PI3K, AKT and mTOR in the cerebral cortex were significantly decreased (P<0.01) in the model group. Compared with the model group, the neurological function score and the percentage of cerebral ischemic volume were significantly decreased (P<0.01). The contents of serum IL-1β, TNF-α, S-100β and NSE were significantly decreased (P<0.01), and the expressions of PI3K, p-PI3K, AKT and mTOR proteins in the cerebral cortex were significantly increased (P<0.01) in three moxibustion groups. Compared with the Moxi 1 and Moxi 2 groups, the above indicators were significantly improved in rats of the Moxi 3 group (P<0.01, P<0.05).

CONCLUSIONS

Moxibustion preconditioning can significantly improve the neurological function of rats after ischemia-reperfusion, inhibit serum inflammatory factors IL-1 β and TNF-α, inhibit brain tissue injury markers S-100β and NSE, which may be related to the activation of PI3K/AKT/mTOR signaling pathway. The protective effect of moxibustion preconditioning for 7 days on CIRI was better than that of 5 days and 3 days.

mTORC1 is required for differentiation of germline stem cells in the Drosophila melanogaster testis

Metabolism participates in the control of stem cell function and subsequent maintenance of tissue homeostasis. How this is achieved in the context of adult stem cell niches in coordination with other local and intrinsic signaling cues is not completely understood. The Target of Rapamycin (TOR) pathway is a master regulator of metabolism and plays essential roles in stem cell maintenance and differentiation. In the Drosophila male germline, mTORC1 is active in germline stem cells (GSCs) and early germ cells. Targeted RNAi-mediated downregulation of mTor in early germ cells causes a block and/or a delay in differentiation, resulting in an accumulation of germ cells with GSC-like features. These early germ cells also contain unusually large and dysfunctional autolysosomes. In addition, downregulation of mTor in adult male GSCs and early germ cells causes non-autonomous activation of mTORC1 in neighboring cyst cells, which correlates with a disruption in the coordination of germline and somatic differentiation. Our study identifies a previously uncharacterized role of the TOR pathway in regulating male germline differentiation.

Genome-wide analyses in Lyme borreliosis: identification of a genetic variant associated with disease susceptibility and its immunological implications

BACKGROUND

Genetic variation underly inter-individual variation in host immune responses to infectious diseases, and may affect susceptibility or the course of signs and symptoms.

METHODS

We performed genome-wide association studies in a prospective cohort of 1138 patients with physician-confirmed Lyme borreliosis (LB), the most common tick-borne disease in the Northern hemisphere caused by the bacterium Borrelia burgdorferi sensu lato. Genome-wide variants in LB patients-divided into a discovery and validation cohort-were compared to two healthy cohorts. Additionally, ex vivo monocyte-derived cytokine responses of peripheral blood mononuclear cells to several stimuli including Borrelia burgdorferi were performed in both LB patient and healthy control samples, as were stimulation experiments using mechanistic/mammalian target of rapamycin (mTOR) inhibitors. In addition, for LB patients, anti-Borrelia antibody responses were measured. Finally, in a subset of LB patients, gene expression was analysed using RNA-sequencing data from the ex vivo stimulation experiments.

RESULTS

We identified a previously unknown genetic variant, rs1061632, that was associated with enhanced LB susceptibility. This polymorphism was an eQTL for KCTD20 and ETV7 genes, and its major risk allele was associated with upregulation of the mTOR pathway and cytokine responses, and lower anti-Borrelia antibody production. In addition, we replicated the recently reported SCGB1D2 locus that was suggested to have a protective effect on B. burgdorferi infection, and associated this locus with higher Borrelia burgdorferi antibody indexes and lower IL-10 responses.

CONCLUSIONS

Susceptibility for LB was associated with higher anti-inflammatory responses and reduced anti-Borrelia antibody production, which in turn may negatively impact bacterial clearance. These findings provide important insights into the immunogenetic susceptibility for LB and may guide future studies on development of preventive or therapeutic measures.

TRIAL REGISTRATION

The LymeProspect study was registered with the International Clinical Trials Registry Platform (NTR4998, registration date 2015-02-13).

Zebrafish raptor mutation inhibits the activity of mTORC1, inducing craniofacial defects due to autophagy-induced neural crest cell death

The mechanistic target of rapamycin (mTOR) coordinates metabolism and cell growth with environmental inputs. mTOR forms two functional complexes: mTORC1 and mTORC2. Proper development requires both complexes but mTORC1 has unique roles in numerous cellular processes, including cell growth, survival and autophagy. Here, we investigate the function of mTORC1 in craniofacial development. We created a zebrafish raptor mutant via CRISPR/Cas9, to specifically disrupt mTORC1. The entire craniofacial skeleton and eyes were reduced in size in mutants; however, overall body length and developmental timing were not affected. The craniofacial phenotype associates with decreased chondrocyte size and increased neural crest cell death. We found that autophagy is elevated in raptor mutants. Chemical inhibition of autophagy reduced cell death and improved craniofacial phenotypes in raptor mutants. Genetic inhibition of autophagy, via mutation of the autophagy gene atg7, improved facial phenotypes in atg7;raptor double mutants, relative to raptor single mutants. We conclude that finely regulated levels of autophagy, via mTORC1, are crucial for craniofacial development.

Anti-proliferation and apoptosis induced via the mTOR/PGC-1α signaling pathway in trophoblast cells of miscarriage

Miscarriage is a common complication during early pregnancy and affects approximately 10%-15% of all pregnant women. Several studies have reported that the abnormal expression of mitochondrial oxidative stress-related genes might be involved in the occurrence and progression of miscarriage. The present study attempted to uncover the role of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) in miscarriage chorionic villous tissue. The hypothesis that PGC-1α is crucial for glycolysis and oxidative phosphorylation during early pregnancy was tested. The results showed that the mRNA and protein levels of PGC-1α were significantly increased in the miscarriage chorionic villous tissues compared with the artificial selective abortion group, and that the expression was regulated by mTOR in knockdown and overexpression of mTOR in HTR8 cell lines. PGC-1α also promoted mitochondrion oxidative phosphorylation but inhibited glycolysis process. In addition, PGC-1α could drive ROS production, reduce mitochondrial membrane potential and block NADPH synthesis, resulting in cell cycle arrest and cell apoptosis, eventually leading to miscarriage. These results suggested that the aberrant expression of PGC-1α is involved in the etiology of early miscarriage, providing new perspectives regarding the mechanisms of miscarriage and a potential therapeutic target for miscarriage.

[LncRNA SNHG11 promotes malignant progression of colorectal cancer cells through the PI3K/Akt/mTOR signaling pathway]

Objective: To investigate the effects of lncRNA SNHG11 on proliferation, migration, invasion and apoptosis of colorectal cancer cancer cells and possible mechanisms. Methods: qRT-PCR was performed to detect the expression level of lncRNA SNHG11 in colorectal cancer tissues and its related cell lines. The correlation between SNHG11 expression and clinical prognosis of patients was assessed by bioinformatics techniques. Cultured CRC cell lines were transfected with shCtrl (shCtrl group), shSNHG11#1 (shSNHG11#1 group), shSNHG11#2 (shSNHG11#2 group), Control cDNA (Control cDNA group), and SNHG11 cDNA (SNHG11 cDNA), respectively. Thiazolyl blue (MTT), clone formation assay, Transwell assay, cell scratch assay, and flow cytometry were used to detect the proliferation, migration, invasion, and apoptosis of CRC cells in each group. Western protein blotting was used to detect the expression of relevant proteins in each group, and the effect of lncRNA SNHG11 knockdown on the growth of tumour cells in vivo was analysed by nude mice tumouring assay. Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signalling pathway inhibitor LY294002 was used for rescue experiments. Results: The expression of lncRNA SNHG11 was significantly higher in colorectal cancer cells and tissues than in normal tissues (P<0.05). Survival analysis showed that the expression level of SNHG11 was not statistically associated with CRC survival (P>0.05). shSNHG11#2 group compared with shCtrl group. MTT OD490/570 values decreased, the number of CRC cell clones decreased, the number of Transwell cells decreased, the area of cell scratch decreased, and the apoptosis rate increased (P<0.05). The mesenchymal markers matrix metalloproteinase (MMP9), N-cadherin and vimentin were significantly reduced, and the expression of the epithelial marker E-cadherin was upregulated. The expression of anti-apoptotic proteins Bcl-2 and Bcl-xl was decreased, and the expression of pro-apoptotic protein Bax was increased (P<0.05).In vivo experiments showed that lncRNA SNHG11 knockdown inhibited the growth of colorectal cancer cells, and the expression of Ki67 was reduced in tumours (P<0.05). LncRNA SNHG11 knockdown inhibited the expression of p-PI3K, p-Akt and p-mTOR.The PI3K/Akt/mTOR signaling pathway inhibitor LY294002 was able to restore the malignant cytological progression of colorectal cancer cells induced by the overexpression of lncRNA SNHG11. Conclusions: LncRNA SNHG11 is highly expressed in colorectal cancer. lncRNA SNHG11 can promote the malignant progression of colorectal cancer cells by regulating the PI3K/Akt/mTOR signaling pathway, and this finding provides a new theoretical basis for targeted therapy of colorectal cancer.

Ferroptosis-related gene glutathione peroxidase 4 promotes reprogramming of glucose metabolism via Akt-mTOR axis in intrahepatic cholangiocarcinoma

The role of the ferroptosis-related gene glutathione peroxidase 4 (GPX4) in oncology has been extensively investigated. However, the clinical implications of GPX4 in patients with intrahepatic cholangiocarcinoma (ICC) remain unknown. This study aimed to evaluate the prognostic impact of GPX4 and its underlying molecular mechanisms in patients with ICC. Fifty-seven patients who underwent surgical resection for ICC between 2010 and 2017 were retrospectively analyzed. Based on the immunohistochemistry, patients were divided into GPX4 high (n = 15) and low (n = 42) groups, and clinical outcomes were assessed. Furthermore, the roles of GPX4 in cell proliferation, migration and gene expression were analyzed in ICC cell lines in vitro and in vivo. The results from clinical study showed that GPX4 high group showed significant associations with high SUVmax on 18F-fluorodeoxyglucose-positron emission tomography (≥8.0, P = 0.017), multiple tumors (P = 0.004), and showed glucose transporter 1 (GLUT1) high expression with a trend toward significance (P = 0.053). Overall and recurrence-free survival in the GPX4 high expression group were significantly worse than those in the GPX4 low expression group (P = 0.038 and P < 0.001, respectively). In the experimental study, inhibition of GPX4 attenuated cell proliferation and migration in ICC cell lines. Inhibition of GPX4 also decreased the expression of glucose metabolism-related genes, such as GLUT1 or HIF1α. Mechanistically, these molecular changes are regulated in Akt-mechanistic targets of rapamycin axis. In conclusion, this study suggested the pivotal value of GPX4 serving as a prognostic marker for patients with ICC. Furthermore, GPX4 can mediate glucose metabolism of ICC.

Solute carrier family 35 member A2 regulates mitophagy through the PI3K/AKT/mTOR axis, promoting the proliferation, migration, and invasion of osteosarcoma cells

The treatment of osteosarcoma patients exhibits individual variability, underscoring the critical importance of targeted therapy. Although (Solute carrier family 35 member A2) SLC35A2's role in the progression of various cancers has been extensively investigated, its specific implications in osteosarcoma remain unexplored. Leveraging data from the (The Cancer Genome Atlas) TCGA and (Genotype-Tissue Expression) GTEx databases, we have discerned that SLC35A2 is notably upregulated in osteosarcoma and correlates with the prognosis of osteosarcoma patients. Consequently, it becomes imperative to delve into the role of SLC35A2 in the context of osteosarcoma. Our research substantiates that SLC35A2 exerts a notable influence on mitochondrial autophagy in osteosarcoma, thereby exerting cascading effects on the proliferation, migration, invasion, and apoptosis of osteosarcoma cells. Mechanistically, SLC35A2 orchestrates mitochondrial autophagy via the PI3K/AKT/mTOR signaling pathway. Moreover, we have conducted rigorous animal experiments to further corroborate the repercussions of SLC35A2 on osteosarcoma growth. In summation, our study elucidates that SLC35A2's modulation of mitochondrial autophagy through the PI3K/AKT/mTOR signaling pathway constitutes a pivotal factor in the malignant progression of osteosarcoma, unveiling promising therapeutic targets for patients grappling with this condition.

mTOR hyperactivity and RICTOR amplification as targets for personalized treatments in malignancies

The increasing knowledge of molecular alterations in malignancies, including mutations and regulatory failures in the mTOR (mechanistic target of rapamycin) signaling pathway, highlights the importance of mTOR hyperactivity as a validated target in common and rare malignancies. This review summarises recent findings on the characterization and prognostic role of mTOR kinase complexes (mTORC1 and mTORC2) activity regarding differences in their function, structure, regulatory mechanisms, and inhibitor sensitivity. We have recently identified new tumor types with RICTOR (rapamycin-insensitive companion of mTOR) amplification and associated mTORC2 hyperactivity as useful potential targets for developing targeted therapies in lung cancer and other newly described malignancies. The activity of mTOR complexes is recommended to be assessed and considered in cancers before mTOR inhibitor therapy, as current first-generation mTOR inhibitors (rapamycin and analogs) can be ineffective in the presence of mTORC2 hyperactivity. We have introduced and proposed a marker panel to determine tissue characteristics of mTOR activity in biopsy specimens, patient materials, and cell lines. Ongoing phase trials of new inhibitors and combination therapies are promising in advanced-stage patients selected by genetic alterations, molecular markers, and/or protein expression changes in the mTOR signaling pathway. Hopefully, the summarized results, our findings, and the suggested characterization of mTOR activity will support therapeutic decisions.

Causal association between mTOR-dependent circulating protein levels and central precocious puberty: a Mendelian randomization study

Background

The mechanistic target of rapamycin (mTOR) signaling pathway has a significant effect on central precocious puberty (CPP). However, the causality between mTOR-dependent circulating protein levels and CPP is still unclear. Our aim is to assess the effects of seven mTOR-dependent circulating protein levels on CPP using Mendelian randomization (MR).

Methods

Instrumental variables (IVs) for mTOR-dependent circulating protein levels were retrieved from the proteomics-GWAS INTERVAL study and eQTLGen. The summary-level genetic datasets for CPP outcome were obtained from the FinnGen Consortium. Inverse-variance weighted (IVW) was used as the primary method and the pleiotropy, heterogeneity and robustness of the analyses were detected as sensitivity analysis. Positive exposures in the discovery cohort would be revalidated in the validation cohort.

Results

This two-sample MR study revealed a causal association between eIF4G level in plasma and CPP in both discovery cohort (IVW: OR = 0.45, 95% CI = 0.22-0.91, p = 0.026) and validation cohort (IVW: OR = 0.45, 95% CI = 0.24-0.85, p = 0.014).

Conclusions

There was a causal association between eIF4G level in plasma and CPP. Whether eIF4G can be used for the prevention or treatment of CPP needs to be explored in further studies.

FHL2 promotes the aggressiveness of lung adenocarcinoma by inhibiting autophagy via activation of the PI3K/AKT/mTOR pathway

BACKGROUND

Increasing evidence indicates that four and a half LIM domains 2 (FHL2) plays a crucial role in the progression of various cancers. However, the biological functions and molecular mechanism of FHL2 in lung adenocarcinoma (LUAD) remain unclear.

METHODS

We evaluated the prognostic value of FHL2 in LUAD using public datasets and further confirmed its prognostic value with our clinical data. The biological functions of FHL2 in LUAD were evaluated by in vitro and in vivo experiments. Pathway analysis and rescue experiments were subsequently performed to explore the molecular mechanism by which FHL2 promoted the progression of LUAD.

RESULTS

FHL2 was upregulated in LUAD tissues compared to adjacent normal lung tissues, and FHL2 overexpression was correlated with unfavorable outcomes in patients with LUAD. FHL2 knockdown significantly suppressed the proliferation, migration and invasion of LUAD cells, while FHL2 overexpression had the opposite effect. Mechanistically, FHL2 upregulated the PI3K/AKT/mTOR pathway and subsequently inhibited autophagy in LUAD cells. The effects FHL2 on the proliferation, migration and invasion of LUAD cells are dependent on the inhibition of autophagy, as of induction autophagy attenuated the aggressive phenotype induced by FHL2 overexpression.

CONCLUSIONS

FHL2 promotes the progression of LUAD by activating the PI3K/AKT/mTOR pathway and subsequently inhibiting autophagy, which can be exploited as a potential therapeutic target for LUAD.

The downregulation of Tapasin in dendritic cell regulates CD8+ T cell autophagy to hamper hepatitis B viral clearance in the induced pluripotent stem cell-derived hepatocyte organoid

Tapasin, a crucial molecular chaperone involved viral antigen processing and presentation, plays an important role in antivirus immunity. However, its impact on T cell differentiation in the context of virus clearance remains unclear. In this study, we employed induced pluripotent stem cells to differentiate into hepatocyte-like cell, which were subsequently inserted to the inverted colloidal crystal scaffolds, thus establishing a hepatocyte organoid (HO). By inoculating hepatitis B virus (HBV) particles in the system, we successfully engineered a robust in vitro HBV infection model for at least 3 weeks. Furthermore, we aimed to explore the effects of lentivirus-mediated short hairpin RNA (shRNA) targeting human Tapasin on the differentiation and antiviral function of CD8+ T cells. Specifically, we transfected dendritic cells (DCs) with Tapasin-shRNA and cocultured with T cells. The results demonstrated that Tapasin-shRNA transfected DCs effectively suppressed T cell proliferation and impeded HBV-specific cytotoxic T lymphocyte responses. Our investigation also revealed the role of mTOR pathway activation in reducing autophagy activity within CD8+ T cells. Expressions of autophagy-related proteins, beclin-1, LC3II/LC3I were decreased and PI3K/AKT/mTOR activity was increased in Tapasin-shRNA group. Collectively, our findings elucidate that shRNA targeting the Tapasin gene within DCs inhibits T cell differentiation by reducing autophagy activity to hamper viral clearance in the HBV-infected HO.

Impulsivity and aggression in alcohol withdrawal syndrome is modulated by the interaction of ZNF804A and mTOR polymorphism

Alcohol withdrawal syndrome (AWS) is a poorly studied phenotype of alcohol use disorder. Understanding the relationship between allelic interactions and AWS-related impulsivity and aggression could have significant implications. This study aimed to investigate the main and interacting effects of ZNF804A and mTOR on impulsivity and aggression during alcohol withdrawal. 446 Chinese Han adult males with alcohol dependence were included in the study. Impulsivity and aggression were assessed, and genomic DNA was genotyped. Single gene analysis showed that ZNF804A rs1344706 (A allele/CC homozygote) and mTOR rs1057079 (C allele/TT homozygote) were strongly associated with AWS-related impulsivity and aggression. In the allelic group, MANOVA revealed a significant gene x gene interaction, suggesting that risk varied systematically depending on both ZNF804A and mTOR alleles. Additionally, a significant interactive effect of ZNF804A rs1344706 and mTOR rs7525957 was found on motor impulsivity and physical aggression, and the ZNF804A rs1344706 gene variant had significant effects on motor impulsivity and physical aggression only in mTOR rs7525957 TT homozygous carriers. The study showed that specific allelic combinations of ZNF804A and mTOR may have protective or risk-enhancing effects on AWS-related impulsivity and aggression.

Treatment of tuberous sclerosis complex manifestations in children with mTOR inhibitors

PURPOSE

Tuberous sclerosis complex (TSC) is a rare autosomal dominant genetic disorder that affects multiple organ systems. Mutations in the TSC1 and TSC2 genes result in the constitutive hyperactivation of the mammalian target of rapamycin (mTOR) pathway, contributing to the growth of benign tumors or hamartomas in various organs. Due to the implication of mTOR pathway dysregulation in the disease pathology, increasing evidence supports the use of mTOR inhibitors for treating multiple manifestations of TSC.

METHODS

In this study, we conducted a retrospective analysis of clinical findings and treatment data from 38 patients diagnosed with tuberous sclerosis who were followed up in the Pediatric Oncology Clinic between 2010 and 2020. We collected information on patients' ages, genders, affected sites, familial history, imaging findings, presence of tumors, and treatments.

RESULTS

Among the patients, nine individuals with TSC manifestations were treated with mTOR inhibitors. Specifically, everolimus was successfully administered to five patients with inborn cardiac rhabdomyoma causing hemodynamic impairment. In addition, two patients with refractory seizures received everolimus in combination with anti-epileptic drugs. A patient with renal angiomyolipomas larger than 3 cm was treated with everolimus, while a patient with extensive facial angiofibroma received topical sirolimus. All patients tolerated the mTOR inhibitors well, and the side effects were deemed acceptable.

CONCLUSION

The utilization of mTOR inhibition in TSC is expected to become more prevalent in clinical practice, as current research is anticipated to provide a better understanding of the therapeutic roles of these treatments in TSC.

NOP14-mediated ribosome biogenesis is required for mTORC2 activation and predicts rapamycin sensitivity

The mechanistic target of rapamycin (mTOR) forms two distinct complexes: rapamycin-sensitive mTOR complex 1 (mTORC1) and rapamycin-insensitive mTORC2. mTORC2 primarily regulates cell survival by phosphorylating Akt, though the upstream regulation of mTORC2 remains less well-defined than that of mTORC1. In this study, we show that NOP14, a 40S ribosome biogenesis factor and a target of the mTORC1-S6K axis, plays an essential role in mTORC2 signaling. Knockdown of NOP14 led to mTORC2 inactivation and Akt destabilization. Conversely, overexpression of NOP14 stimulated mTORC2-Akt activation and enhanced cell proliferation. Fractionation and coimmunoprecipitation assays demonstrated that the mTORC2 complex was recruited to the rough endoplasmic reticulum through association with endoplasmic reticulum-bound ribosomes. In vivo, high levels of NOP14 correlated with poor prognosis in multiple cancer types. Notably, cancer cells with NOP14 high expression exhibit increased sensitivity to mTOR inhibitors, because the feedback activation of the PI3K-PDK1-Akt axis by mTORC1 inhibition was compensated by mTORC2 inhibition partly through NOP14 downregulation. In conclusion, our findings reveal a spatial regulation of mTORC2-Akt signaling and identify ribosome biogenesis as a potential biomarker for assessing rapalog response in cancer therapy.

EGCG-induced selective death of cancer cells through autophagy-dependent regulation of the p62-mediated antioxidant survival pathway

The effects of EGCG on the selective death of cancer cells by modulating antioxidant pathways through autophagy were explored in various normal and cancer cells. EGCG positively regulated the p62-KEAP1-NRF2-HO-1 pathway in normal cells, while negatively regulating it in cancer cells, leading to selective apoptotic death of cancer cells. In EGCG-treated MRC5 cells (EGCG-MRC5), autophagic flux was blocked, which was accompanied by the formation of p62-positive aggregates. However, EGCG-treated HeLa cells (EGCG-HeLa) showed incomplete autophagic flux and no aggregate formation. The levels of P-ULK1 S556 and S758 increased in EGCG-MRC5 through AMPK-mTOR cooperative interaction. In contrast, EGCG treatment in HeLa cells led to AMPK-induced mTOR inactivation, resulting in abrogation of P-ULK1 S556 and S758 levels. AMPK knockout in EGCG-HeLa restored positive regulation of the p62-mediated pathway, which was accompanied by increased P-mTOR S2448 and P-ULK1 S758 levels. Knockdown of 67LR in EGCG-HeLa abolished AMPK activity but did not restore the p62-mediated pathway. Surprisingly, both AMPK knockout and 67LR knockdown in EGCG-HeLa markedly increased cell viability, despite differential regulation of the antioxidant enzyme HO-1. In conclusion, EGCG induces the selective death of cancer cells through the modulation of at least two autophagy-dependent and independent regulatory pathways: negative regulation involves the mTOR-ULK1 (S556 and S758)-p62-KEAP1-NRF2-HO-1 axis via AMPK activation, whereas positive regulation occurs through the 67LR-AMPK axis.

EID3 inhibits the osteogenic differentiation of periodontal ligament stem cells and mediates the signal transduction of TAZ-EID3-AKT/MTOR/ERK

Exploring the molecular mechanisms of cell behaviors is beneficial for promoting periodontal ligament stem cell (PDLSC)-mediated tissue regeneration. This study intends to explore the regulatory effects of EID3 on cell proliferation, apoptosis, and osteogenic differentiation and to preliminarily explore the regulatory mechanism of EID3. Here, EID3 was overexpressed or knocked down in PDLSCs by recombinant lentivirus. Then, cell proliferation activity was analyzed by colony-forming assay, EdU assay, and cell cycle assay. Cell apoptosis was detected by flow cytometry. The osteo-differentiation potential was analyzed using ALP activity assay, ALP staining, alizarin red staining, and mRNA and protein assay of osteo-differentiation related genes. The results showed that when EID3 was knocked down, the proliferation activity and osteogenic differentiation potential of PDLSCs decreased, while they increased when EID3 was overexpressed. The cell apoptosis rate decreased in PDLSCs with EID3 knockdown but increased in PDLSCs with EID3 overexpression. Moreover, EID3 inhibited the transduction of the AKT/MTOR and ERK signaling pathway. In addition, TAZ negatively regulated the expression of EID3, and the overexpression of EID3 partially reversed the promotive effects of TAZ on the osteogenic differentiation of PDLSCs. Taken together, EID3 inhibits the proliferation and osteogenic differentiation while promoting the apoptosis of PDLSCs. EID3 inhibits the transduction of the AKT/MTOR and ERK signaling pathways and mediates the regulatory effect of TAZ on PDLSC osteogenic differentiation.

Manganese induces neuronal apoptosis by activating mTOR signaling pathway in vitro and in vivo

Manganese (Mn) is a well-known environmental pollutant and occupational toxicant that causes neurotoxicity, which present as neurodegenerative-like symptoms. However, the mechanism of Mn-induced neuronal injury remains unclear. In this research, we explored the mechanism of Mn-induced neurotoxicity, focusing on the mTOR signaling pathway. A plasmid expressing a short hairpin RNA (shRNA) targeting mTOR (shRNA-mTOR) was transfected into N27 cells in vitro, and rapamycin was used as an mTOR inhibitor in vivo to block the mTOR signaling pathway. Cells were treated with different concentrations of manganese (II) chloride (MnCl2). We found that Mn induced cell injury and apoptosis and markedly upregulated the expression of mTOR pathway-related proteins. The phosphorylation of 4E-BP1, S6K1, Akt and SGK1 was markedly decreased after blocking mTOR, and cell apoptosis was also reduced. Furthermore, the mTOR-specific inhibitor rapamycin restored learning and memory abilities in vivo. This research highlights that inhibiting mTOR might be useful for preventing Mn-induced neurodegenerative-like disorders.

Renal Cell Carcinoma Associated With TSC/MTOR Genomic Alterations: An Update on its Expanding Spectrum and an Approach to Clinicopathologic Work-up

Renal cell carcinoma (RCC) with tuberous sclerosis complex (TSC)/mammalian target of rapamycin (MTOR) pathway-related genomic alterations have been classically described in hereditary TSC syndrome setting involving germline mutations, whereby cells with a bi-allelic inactivation of genes originate tumors in a classic tumor-suppressor "two-hit" Knudson paradigm. Initial studies of TSC-associated RCC categorized tumors into 3 broad heterogeneous morphologic groups: RCC with smooth muscle stroma, chromophobe-like, and eosinophilic-macrocytic. Recently, a similar morphologic spectrum has been increasingly recognized in novel and emerging entities characterized by somatic mutations in the TSC1/2 and MTOR in patients who do not suffer from the TSC. Correct recognition of RCC with TSC / MTOR mutations is critical for accurate prognostication because such tumors with aggressive behavior have the potential to be tailored to mTOR inhibitors. Whether TSC/MTOR mutated renal epithelial neoplasms represent a distinct molecular class has been confounded by the fact that TSC1/2 , and the gene encoding the downstream protein MTOR, are mutated secondarily in ∼5% of the more common subtypes of RCC, including the commonest subtype of clear cell RCC. This review summarizes the expanding morphologic spectrum of renal tumors with TSC/mTOR pathway alterations, specifically for sporadically occurring tumors where these genomic alterations likely are primary pathologic events. Finally, a practical surgical pathology approach to handling these tumors, and a conceptual framework of renal epithelial tumors with TSC/MTOR mutations as a "family of tumors", is presented.

Methylation of GPRC5A promotes liver metastasis and docetaxel resistance through activating mTOR signaling pathway in triple negative breast cancer

AIMS

This study aims to explore the function and mechanism of G Protein-coupled receptor class C group 5 member A (GPRC5A) in docetaxel-resistance and liver metastasis of breast cancer.

METHODS

Single-cell RNA transcriptomic analysis and bioinformatic analysis are used to screen relevant genes in breast cancer metastatic hepatic specimens. MeRIP, dual-luciferase analysis and bioinformation were used to detect m6A modulation. Mass spectrometry (MS), co-inmunoprecipitation (co-IP) and immunofluorescence colocalization were executed to explore the mechanism of GPRC5A in breast cancer cells.

RESULT

GPRC5A was upregulated in triple-negative breast cancer (TNBC) and was associated with a poor prognosis. In vitro and in vivo experiments demonstrated that knockdown of GPRC5A alleviated metastasis and resistance to docetaxel in TNBC. Overexpression of GPRC5A had the opposite effects. The m6A methylation of GPRC5A mRNA was modulated by METTL3 and YTHDF1, which facilitates its translation. GPRC5A inhibited the ubiquitination-dependent degradation of LAMTOR1, resulting in the recruitment of mTORC1 to lysosomes and activating the mTORC1/p70s6k signaling pathway.

CONCLUSION

METTL3/YTHDF1 axis up-regulates GPRC5A expression by m6A methylation. GPRC5A activates mTORC1/p70s6k signaling pathway by recruiting mTORC1 to lysosomes, consequently promotes docetaxel-resistance and liver metastasis.

TMEM65 promotes gastric tumorigenesis by targeting YWHAZ to activate PI3K-Akt-mTOR pathway and is a therapeutic target

Copy number alterations are crucial for the development of gastric cancer (GC). Here, we identified Transmembrane Protein 65 (TMEM65) amplification by genomic hybridization microarray to profile copy-number variations in GC. TMEM65 mRNA level was significantly up-regulated in GC compared to adjacent normal tissues, and was positively associated with TMEM65 amplification. High TMEM65 expression or DNA copy number predicts poor prognosis (P < 0.05) in GC. Furtherly, GC patients with TMEM65 amplification (n = 129) or overexpression (n = 78) significantly associated with shortened survival. Ectopic expression of TMEM65 significantly promoted cell proliferation, cell cycle progression and cell migration/invasion ability, but inhibited apoptosis (all P < 0.05). Conversely, silencing of TMEM65 in GC cells showed opposite abilities on cell function in vitro and suppressed tumor growth and lung metastasis in vivo (all P < 0.01). Moreover, TMEM65 depletion by VNP-encapsulated TMEM65-siRNA significantly suppressed tumor growth in subcutaneous xenograft model. Mechanistically, TMEM65 exerted oncogenic effects through activating PI3K-Akt-mTOR signaling pathway, as evidenced of increased expression of key regulators (p-Akt, p-GSK-3β, p-mTOR) by Western blot. YWHAZ (Tyrosine 3-Monooxygenase/Tryptophan 5-Monooxygenase) was identified as a direct downstream effector of TMEM65. Direct binding of TMEM65 with YWHAZ in the cytoplasm inhibited ubiquitin-mediated degradation of YWHAZ. Moreover, oncogenic effect of TMEM65 was partly dependent on YWHAZ. In conclusion, TMEM65 promotes gastric tumorigenesis by activating PI3K-Akt-mTOR signaling via cooperating with YWHAZ. TMEM65 overexpression may serve as an independent new biomarker and is a therapeutic target in GC.

mTOR pathway occupies a central role in the emergence of latent cancer cells

The current focus in oncology research is the translational control of cancer cells as a major mechanism of cellular plasticity. Recent evidence has prompted a reevaluation of the role of the mTOR pathway in cancer development leading to new conclusions. The mechanistic mTOR inhibition is well known to be a tool for generating quiescent stem cells and cancer cells. In response to mTOR suppression, quiescent cancer cells dynamically change their proteome, triggering alternative non-canonical translation mechanisms. The shift to selective translation may have clinical relevance, since quiescent tumor cells can acquire new phenotypical features. This review provides new insights into the patterns of mTOR functioning in quiescent cancer cells, enhancing our current understanding of the biology of latent metastasis.

BOP1 contributes to the activation of autophagy in polycystic ovary syndrome via nucleolar stress response

Abnormal autophagy is one of the vital features in polycystic ovary syndrome (PCOS). However, the underlying molecular mechanisms remain unelucidated. In this study, we aimed to investigate whether Block of Proliferation 1 (BOP1) is involved in the onset of autophagy activation of granulosa cells in PCOS. Firstly, we found that BOP1 expression was significantly down-regulated in the ovaries of PCOS mice, which was associated with the development of PCOS. Next, local injection of lentiviral vectors in the ovary for the overexpression of BOP1 significantly alleviated the phenotypes of elevated androgens, disturbed estrous cycle, and abnormal follicular development in PCOS mice. Subsequently, we found that knockdown of BOP1 activated autophagy of granulosa cells in the in vitro experiments, whereas overexpression of BOP1 inhibited autophagy in both in vivo and in vitro models. Mechanistically, BOP1 knockdown triggered the nucleolus stress response, which caused RPL11 to be released from the nucleolus into the nucleoplasm and inhibited the E3 ubiquitination ligase of MDM2, thereby enhancing the stability of p53. Subsequently, P53 inhibited mTOR, thereby activating autophagy in granulosa cells. In addition, the mRNA level of BOP1 was negatively correlated with antral follicle count (AFC), body-mass index (BMI), serum androgen levels, and anti-Mullerian hormone (AMH) in patients with PCOS. In summary, our study demonstrates that BOP1 downregulation inhibits mTOR phosphorylation through activation of the p53-dependent nucleolus stress response, which subsequently contributes to aberrant autophagy in granulosa cells, revealing that BOP1 may be a key target for probing the mechanisms of PCOS.

[Effect of Bushen Huoxue（） recipe on autophagy of ovariectomized rat chondrocytes based on Akt/mTOR signaling pathway]

OBJECTIVE

To investigate whether Bushen Huoxue recipe can protect articular cartilage by regulating Akt/mTOR signaling pathway to promote the autophagy of chondrocytes in ovariectomized rats.

METHODS

Among 30 SPF 12-week-old female SD rats weighing （247.0±7.0） g, 6 were randomly selected as the blank control group, and the remaining rats were randomly divided into model group, BSHXR-L group, BSHXR-M group and BSHXR-H group, with 6 rats in each group. The protective effect of Bushen Huoxue recipe on articular cartilage injury in rats was determined by visual observation score, muscovine O-solid green staining and immunohistochemistry. The expression of autophagy related proteins was detected by Western-blot, and the relative expression of Akt, mTOR and downstream autophagy genes was detected by qPCR.

RESULTS

After modeling, BSHXR （L, M, H） groups could alleviate the histological damage of cartilage. Immunohistochemistry showed that the expression of Collagen-Ⅱand Aggrecan gradually increased, and the expression of MMP-13 gradually decreased, and the differences between BSHXR-M and BSHXR-H groups and model group were statistically significant （P<0.05）. The results of Western-blot showed that the autophagy pathway proteins p-Akt/Akt and p-mTOR/mTOR were inhibited in the BSHXR（L, M, H） groups, and the expressions of downstream proteins Beclin-1 and LC3Ⅱwere gradually increased, while p62 was gradually decreased, showing a dose effect. QPCR results showed that BSHXR（L, M, H） groups could promote the relative expression of Beclin-1 and LC3ⅡmRNA, and inhibit the relative expression of p62, Akt, mTOR mRNA, and the differences were statistically significant compared with model group （P<0.05）.

CONCLUSION

Bushen Huoxue recipe can enhance the cartilage autophagy response by inhibiting the Akt/mTOR signaling pathway, and then protect the cartilage.

SNAT2-mediated regulation of estrogen and progesterone in the proliferation of goat mammary epithelial cells

The development of the goat mammary gland is mainly under the control of ovarian hormones particularly estrogen and progesterone (P4). Amino acids play an essential role in mammary gland development and milk production, and sodium-coupled neutral amino acid transporter 2 (SNAT2) was reported to be expressed in the mammary gland of rats and bovine mammary epithelial cells, which may affect the synthesis of milk proteins or mammary cell proliferation by mediating prolactin, 17β-estradiol (E2) or methionine function. However, whether SNAT2 mediates the regulatory effects of E2 and P4 on the development of the ruminant mammary gland is still unclear. In this study, we show that E2 and P4 could increase the proliferation of goat mammary epithelial cells (GMECs) and regulate SNAT2 mRNA and protein expression in a dose-dependent manner. Further investigation revealed that SNAT2 is abundantly expressed in the mammary gland during late pregnancy and early lactation, while knockdown and overexpression of SNAT2 in GMECs could inhibit or enhance E2- and P4-induced cell proliferation as well as mammalian target of rapamycin (mTOR) signaling. We also found that the accelerated proliferation induced by SNAT2 overexpression in GMECs was suppressed by the mTOR signaling pathway inhibitor rapamycin. This indicates that the regulation of GMECs proliferation mediated by SNAT2 in response to E2 and P4 is dependent on the mTOR signaling pathway. Finally, we found that the total content of the amino acids in GMECs changed after knocking-down and overexpressing SNAT2. In summary, the results demonstrate that the regulatory effects of E2 and P4 on GMECs proliferation may be mediated by the SNAT2-transported amino acid pathway. These results may offer a novel nutritional target for improving the development of the ruminant mammary gland and milk production.

The possible effects of the MTOR polymorphisms on preeclampsia susceptibility, severity, and onset: a case-control study and in silico analysis

BACKGROUND

Preeclampsia (PE) is a gestational complication with developed hypertension and proteinuria. Evidence showed the role of mTOR in various cellular processes. Therefore, this study aimed to evaluate the effects of MTOR polymorphisms on susceptibility, severity, and onset of Preeclampsia (PE).

METHODS AND RESULTS

A total of 250 PE pregnant women and 258 age-matched control subjects were recruited in this study. To genotype MTOR polymorphisms, the PCR-RFLP method was used. The SpliceAid 2 and PROMO tools were used for in silico analysis. The maternal MTOR rs17036508T/C polymorphism was associated with PE risk in various genetic models. There was no relationship between rs2536T/C and rs2295080T/G polymorphisms and PE. The TTC and TGC haplotypes of rs2536/ rs2295080/ rs17036508 polymorphisms were significantly higher in PE women. Subgroup analysis revealed the association between the MTOR rs2295080 variant and an increased risk of Early-onset PE (EOPE). However, the MTOR rs17036508 was associated with a higher risk of EOPE and Late- Onset PE. In addition, the MTOR rs2295080 could increase the risk of severe PE. The results of the in silico analysis showed that rs17036508 disrupted several binding motifs in the mutant sequence. The PROMO database revealed that the T to C substitution leads to the loss of the TFII-I binding site in the mutant allele.

CONCLUSION

The MTOR rs17036508T/C polymorphism was associated with PE risk. There was an association between the MTOR rs2295080 variant and an increased risk of EOPE. The MTOR rs17036508T/C and rs2295080T/C variants could disrupt several binding motifs and TFII-I binding respectively.

Bergenin Alleviates Ulcerative Colitis By Decreasing Gut Commensal Bacteroides vulgatus-Mediated Elevated Branched-Chain Amino Acids

Ulcerative colitis is closely associated with the dysregulation of gut microbiota. There is growing evidence that natural products may improve ulcerative colitis by regulating the gut microbiota. In this research, we demonstrated that bergenin, a naturally occurring isocoumarin, significantly ameliorates colitis symptoms in dextran sulfate sodium (DSS)-induced mice. Transcriptomic analysis and Caco-2 cell assays revealed that bergenin could ameliorate ulcerative colitis by inhibiting TLR4 and regulating NF-κB and mTOR phosphorylation. 16S rRNA sequencing and metabolomics analyses revealed that bergenin could improve gut microbiota dysbiosis by decreasing branched-chain amino acid (BCAA) levels. BCAA intervention mediated the mTOR/p70S6K signaling pathway to exacerbate the symptoms of ulcerative colitis in mice. Notably, bergenin greatly decreased the symbiotic bacteria Bacteroides vulgatus (B. vulgatus), and the gavage of B. vulgatus increased BCAA concentrations and aggravated the symptoms of ulcerative colitis in mice. Our findings suggest that gut microbiota-mediated BCAA metabolism plays a vital role in the protective effect of bergenin on ulcerative colitis, providing novel insights for ulcerative colitis prevention through manipulation of the gut microbiota.

Distinct roles of LARP1 and 4EBP1/2 in regulating translation and stability of 5'TOP mRNAs

A central mechanism of mTOR complex 1 (mTORC1) signaling is the coordinated translation of ribosomal protein and translation factor mRNAs mediated by the 5'-terminal oligopyrimidine motif (5'TOP). Recently, La-related protein 1 (LARP1) was proposed to be the specific regulator of 5'TOP mRNA translation downstream of mTORC1, while eIF4E-binding proteins (4EBP1/2) were suggested to have a general role in translational repression of all transcripts. Here, we use single-molecule translation site imaging of 5'TOP and canonical mRNAs to study the translation of single mRNAs in living cells. Our data reveal that 4EBP1/2 has a dominant role in repression of translation of both 5'TOP and canonical mRNAs during pharmacological inhibition of mTOR. In contrast, we find that LARP1 selectively protects 5'TOP mRNAs from degradation in a transcriptome-wide analysis of mRNA half-lives. Our results clarify the roles of 4EBP1/2 and LARP1 in regulating 5'TOP mRNAs and provide a framework to further study how these factors control cell growth during development and disease.

Plin2 inhibits autophagy via activating AKT/mTOR pathway in non-small cell lung cancer

Perilipin 2 (Plin2) is known to be dysregulated in several human malignancies, which facilitates cancer progression. Recent studies have found that the abnormal expression of Plin2 is associated with poor prognosis of non-small cell lung cancer (NSCLC). However, the specific role of Plin2 and its underlying mechanism remain unclear. This study revealed that Plin2 expression was low in NSCLC tissues, and its relatively higher expression indicated larger tumor size and poorer prognosis. In vitro experiments proved that Plin2 promoted NSCLC cellular proliferation and inhibited autophagy by activating the AKT/mTOR pathway. Meanwhile, treatment with the AKT phosphorylation promoter or inhibitor neutralized the influence of Plin2 depletion or over-expression on proliferation and autophagy, respectively. In vivo study showed that Plin2 stimulated subcutaneous tumorigenesis of NSCLC cells in nude mice. Collectively, this study clarified the carcinogenic role of Plin2 and its molecular mechanism in NSCLC progression, which may facilitate a targeted therapy in the future.

The SLC38A9-mTOR axis is involved in autophagy in the juvenile yellow catfish (Pelteobagrus fulvidraco) under ammonia stress

The primary objective of this study was to examine the effect of acute ammonia stress on hepatic physiological alterations in yellow catfish by performing a comprehensive analysis of the metabolome and transcriptome. The present study showed that ammonia stress led to liver metabolic disruption, functional incapacitation, and oxidative damage. Transcriptomic and metabolomic analyses revealed transcriptional and metabolic differences in the liver of yellow catfish under control and high ammonia stress conditions. After 96 h of acute exposure to ammonia, the mRNA levels of 596 liver genes were upregulated, whereas those of 603 genes were downregulated. Enrichment analysis of the differentially expressed genes identified multiple signalling pathways associated with autophagy, including the endocytosis, autophagy-animal, and mammalian target of rapamycin signalling pathways. A total of 186 upregulated and 117 downregulated metabolites, primarily associated with amino acid biosynthesis pathways, were identified. Multi-omics integration revealed the solute carrier family 38 member 9 (SLC38A9)-mammalian target of rapamycin axis as a signalling nexus for amino acid-mediated modulation of autophagy flux, and q-PCR was used to assess the expression of autophagy-related genes (LC3a and sqstm1), revealing an initial inhibition followed by the restoration of autophagic flux during ammonia stress. Subsequent utilisation of arginine as a specific SLC38A9 activator during ammonia stress demonstrated that augmented SLC38A9 expression hindered autophagy, exacerbated ammonia toxicity, and caused a physiological decline (total cholesterol, total triglyceride, acid phosphatase, alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase levels were significantly increased), oxidative stress, and apoptosis. Autophagy activation may be an adaptive mechanism to resist ammonia stress.

Phase I Study of mTORC1/2 Inhibitor Sapanisertib (CB-228/TAK-228) in Combination with Metformin in Patients with mTOR/AKT/PI3K Pathway Alterations and Advanced Solid Malignancies

BACKGROUND

Sapanisertib (CB-228/TAK-228) is a potent, selective ATP-competitive, dual inhibitor of mTORC1/2. Metformin is thought to inhibit the mTOR pathway through upstream activation of 5'-AMP-activated protein kinase (AMPK) suggesting combination therapy may enhance antitumor activity of sapanisertib. We report preliminary safety, tolerability, and efficacy from the dose-escalation study of sapanisertib in combination with metformin in patients with advanced solid tumors.

METHODS

Patients with advanced metastatic solid tumors resistant or refractory to standard treatment, with and without mTOR/AKT/PI3K pathway alterations, received sapanisertib 3 or 4 mg daily together with metformin once to three times daily (500-1,500 mg). All patients underwent 14-day titration period for metformin in cycle 1. Tumor measurements were performed following cycle 2 and subsequently every 8 weeks.

RESULTS

A total of 30 patients were enrolled across four cohorts (3 mg/500 mg; 3 mg/1,000 mg, 4 mg/1,000 mg; 4 mg/1,500 mg). 19 were female (63%), median age was 57 (range: 30-77), all were Eastern Cooperative Oncology Group performance status 1. Tumor types included sarcoma (6), breast (4), ovarian (4), head and neck (3), colorectal (2), lung (2), renal cell (2), endometrial (2), gastroesophageal junction (1), prostate (1), stomach (1), urachus (1), and cervical cancer (1). Median number of prior lines of therapy was 4. Most common genomic alterations included PIK3CA (27%), PTEN (17%), AKT1/2 (10%), mTOR (10%). Of 30 patients evaluable for response, 4 patients achieved partial response (PR); 15 patients achieved stable disease (SD) as best response. Disease control rate (PR+SD) was 63%. Of the responders in PR, 3 of 4 patients had documented PTEN mutations (3/5 patients enrolled with PTEN mutations had PR); 2 of 4 of patients in PR had comutations (patient with leiomyosarcoma had both PTEN and TSC; patient with breast cancer had both PTEN and STK11); 1 of 4 patients in PR had AKT and mTOR mutation; tumor types included leiomyosarcoma (n = 2), breast (n = 1), and endometrial cancer (n = 1). Most common treatment-emergent adverse events included nausea, anorexia, diarrhea, and rash. Grade (G) 3-5 treatment-related adverse events included hyperglycemia (4/30; 13%), fatigue (2/30; 7%), hypertriglyceridemia (1/30; 3%), rash (2/20; 7%), diarrhea (2/30; 7%), creatinine increase (1/30; 3%), acidosis (1/30; 3%). No dose-limiting toxicities (DLT) were reported in the 3 mg/500 mg cohort. One of 6 patient had DLT in the 3 mg/1,000 mg cohort (G3 diarrhea) and 2 of 11 patients had DLTs in the 4 mg/1,500 mg cohort (G3 fatigue, G3 rash). 4 mg/1,000 mg was defined as the MTD.

CONCLUSIONS

The safety profile of mTORC1/2 inhibitor sapanisertib in combination with metformin was generally tolerable, with antitumor activity observed in patients with advanced malignancies harboring PTEN mutations and AKT/mTOR pathway alterations.

SIGNIFICANCE

Sapanisertib (CB-228/TAK-228) is a potent, selective ATP-competitive, next-generation dual inhibitor of mTORC1/2. Metformin is thought to inhibit the mTOR pathway through upstream activation of AMPK suggesting combination therapy may enhance antitumor activity of sapanisertib. This dose-escalation study of sapanisertib and metformin in advanced solid tumors and mTOR/AKT/PI3K pathway alterations, demonstrates safety, tolerability, and early clinical activity in advanced malignancies harboring PTEN mutations and AKT/mTOR pathway alterations.Clinical trial information: NCT03017833.

miR-1304 targets KLK11 to regulate gastric cancer cell proliferation through the mTOR signaling pathway

OBJECTIVE

Gastric cancer (GC) is prevalent worldwide but has a dismal prognosis, and its molecular and pathogenic pathways remain unknown. Kallikrein 11 (KLK11) has a reduced expression in GC and may be a promising biomarker.

METHOD

Herein, the function of KLK11 in GC and its regulatory mechanism was studied. Gene sequencing and quantitative reverse transcription-polymerase chain reaction were used to determine the expression of KLK11 in GC and precancerous lesions. Cell function tests and flow cytometry were conducted to determine the proliferative capacity and cell cycle of GC cells, respectively. A luciferase reporter test confirmed the interaction between RNA molecules. The mTOR/4E-BP1 signaling pathway was analyzed using western blotting.

RESULT

KLK11 has a suppressed expression in GC samples. KLK11 decreased the proliferative capacity of GC cells, by inhibiting the degree of mTOR/4E-BP1 phosphorylation. In contrast, miR-1304 increased GC cell proliferation by inhibiting KLK11. Moreover, KLK11 was able to limit in vivo GC cell proliferation.

CONCLUSION

These findings reveal a promising strategy to prevent and treat GC by targeting the KLK11-mediated mTOR/4E-BP1 cascade.

Potential role of the lncRNA "HOTAIR"/miRNA "206"/BDNF network in the alteration in expression of synaptic plasticity gene arc and BDNF level in sera of patients with heroin use disorder through the PI3K/AKT/mTOR pathway compared to the controls

INTRODUCTION

Heroin use disorder (HUD) is a seriously increasing health issue, accounting for most deaths among drug abusers. Studying non-coding ribonucleic acid gene expression among drug abusers is a promising approach, as it may be used in diagnosis and therapeutics.

PARTICIPANTS AND METHODS

A total of 49 male heroin-dependent patients and 49 male control participants were recruited from Kasr Al Ainy Psychiatry and Addiction outpatient clinics, Faculty of Medicine, Cairo University. Sera were gathered. qRT-PCR was utilized for the detection of gene expression of non-coding RNAs such as "HOX transcript antisense RNA" (HOTAIR), micro-RNA (miRNA-206), phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), mechanistic target of rapamycin (mTOR), and Activity Regulated Cytoskeleton Associated Protein (Arc). Sera Brain-Derived Neurotrophic Factor (BDNF) levels were assessed using ELISA. Using a western blot made it possible to determine the protein expression of PI3K, AKT, and mTOR.

RESULTS

The study demonstrated that gene expressions of HOTAIR, AKT, PI3K, and Arc were considerably lowered between cases and controls, while gene expressions of miR-206 and mTOR1 were significantly raised. PI3K and AKT protein expressions were downregulated, while mTOR expressions were upregulated. BDNF levels were significantly decreased in some cases.

CONCLUSION

The results of this study suggest that decreased HOTAIR in HUD relieves miR-206 inhibition, which thus increases and affects downstream PI3K/AKT/mTOR, ARC, and BDNF expression. This may be shared in addictive and relapsing behaviors.

PI3K/mTOR is a therapeutically targetable genetic dependency in diffuse intrinsic pontine glioma

Diffuse midline glioma (DMG), including tumors diagnosed in the brainstem (diffuse intrinsic pontine glioma; DIPG), are uniformly fatal brain tumors that lack effective treatment. Analysis of CRISPR/Cas9 loss-of-function gene deletion screens identified PIK3CA and MTOR as targetable molecular dependencies across patient derived models of DIPG, highlighting the therapeutic potential of the blood-brain barrier-penetrant PI3K/Akt/mTOR inhibitor, paxalisib. At the human-equivalent maximum tolerated dose, mice treated with paxalisib experienced systemic glucose feedback and increased insulin levels commensurate with patients using PI3K inhibitors. To exploit genetic dependence and overcome resistance while maintaining compliance and therapeutic benefit, we combined paxalisib with the antihyperglycemic drug metformin. Metformin restored glucose homeostasis and decreased phosphorylation of the insulin receptor in vivo, a common mechanism of PI3K-inhibitor resistance, extending survival of orthotopic models. DIPG models treated with paxalisib increased calcium-activated PKC signaling. The brain penetrant PKC inhibitor enzastaurin, in combination with paxalisib, synergistically extended the survival of multiple orthotopic patient-derived and immunocompetent syngeneic allograft models; benefits potentiated in combination with metformin and standard-of-care radiotherapy. Therapeutic adaptation was assessed using spatial transcriptomics and ATAC-Seq, identifying changes in myelination and tumor immune microenvironment crosstalk. Collectively, this study has identified what we believe to be a clinically relevant DIPG therapeutic combinational strategy.

MHY1485 promotes adriamycin sensitivity in HepG2 cells by inhibiting autophagy

MHY1485 is an mTOR activator that inhibits the autophagy process by inhibiting the fusion between autophagosomes and lysosomes. This study aimed to explore the role and mechanism of MHY1485 in hepatocellular carcinoma (HCC) and to provide an in-depth understanding of the mechanisms of autophagy regulation in relation to adriamycin (ADM) resistance, as well as the development of a molecularly targeted autophagy-modulating approach. Here, ADM was used to treat HepG2 cells and construct an ADM-resistant cell model. The HepG2/ADM cell line and HepG2 cells were treated with MHY1485 and ADM, respectively, and the proliferation and apoptosis of HCC cells were detected using CCK8, clone formation, flow cytometry, and 5-ethynyl-2'-deoxyuridine staining assays. Ki-67, mTOR phosphorylation, and LC3A expression were detected by IF staining; the expression or phosphorylation levels of autophagy-related proteins (i.e., GLUT1, PGI, PFK, END, and MTHFD2) and apoptosis-related proteins (caspase-3, caspase-8, and caspase-9) were detected by qPCR and western blotting. The number of autophagosomes was determined by monodansylcadaverine staining. Our results showed that MHY1485 can inhibit the proliferation and growth of liver cancer cells, and that MHY1485 combined with ADM can effectively inhibit the tolerance of HepG2/ADM cells to ADM and enhance the efficacy of ADM. The results of the detection of the autophagy-related protein LC3A also indicated that MHY1485 activates mTOR and can affect the phosphorylation level of ULK1, inhibit autophagy, and enhance the sensitivity of liver cancer cells to adriamycin. In summary, MHY1485 can enhance the sensitivity of adriamycin-resistant cells to adriamycin by activating mTOR and blocking the autophagy process in cells; therefore, mTOR may become a potential target for the treatment of liver cancer.

Roles of Rictor alterations in gastrointestinal tumors (Review)

Gastrointestinal tumors account for five of the top 10 causes of mortality from all cancers (colorectal, liver, stomach, esophageal and pancreatic cancer). Mammalian target of rapamycin (mTOR) signaling is commonly dysregulated in various human cancers. As a core component of the mTOR complex 2 (mTORC2), Rictor is a key effector molecule of the PI3K/Akt pathway. A high alteration rate of Rictor has been observed in gastrointestinal tumors, and such Rictor alterations are often associated with resistance to chemotherapy and related adverse clinical outcomes. However, the exact roles of Rictor in gastrointestinal tumors remain elusive. The aim of the present study was to critically discuss the following: i) Mutation and biological characteristics of Rictor in tumors with a detailed overview of Rictor in cell proliferation, angiogenesis, apoptosis, autophagy and drug resistance; ii) the role of Rictor in tumors of the digestive system, particularly colorectal, hepatobiliary, gastric, esophageal and pancreatic cancer and cholangiocarcinoma; and iii) the current status and prospects of targeted therapy for Rictor by inhibiting Akt activation. Despite the growing realization of the importance of Rictor/mTORC2 in cancer, the underlying mechanistic details remain poorly understood; this needs to change in order for the development of efficient targeted therapies and re‑sensitization of therapy‑resistant cancers to be made possible.

Low vitamin D during pregnancy is associated with infantile eczema by up-regulation of PI3K/AKT/mTOR signaling pathway and affecting FOXP3 expression: A bidirectional cohort study

Vitamin D has received increasing attention because of its association with atopic disease development. Limited studies that have been done on the impact of maternal vitamin D levels during pregnancy on infantile eczema are still debatable. We wanted to discover the effect of maternal vitamin D on infantile eczema and explore whether regulatory T cells (Treg) play a role in this process. 219 pairs of mothers and children were enrolled. Maternal fasting venous blood was collected in pregnancy's second and third trimesters to determine vitamin D levels. Cord blood and placenta samples were collected during childbirth for detecting levels of genes, proteins and cytokines. Pediatricians followed up the prevalence of eczema in infants within 1 year. The reported rate of vitamin D deficiency and insufficiency was 35.6% and 28.3%. Lower maternal 25(OH)D3 levels were related to a higher risk of infantile eczema. Foxp3 gene expression is lower in cord blood of infants with eczema compared to infants without eczema. There was a positive correlation between maternal 25(OH)D3 levels and the expression of FOXP3 gene in cord blood. Compared to vitamin D sufficiency women, vitamin D deficiency women's placental FOXP3 protein expression was decreased and PI3K/AKT/mTOR protein was up-regulated. Our study demonstrates that low prenatal maternal vitamin D levels increased the risk of infantile eczema aged 0-1 year, which might be related to the downregulating of the FOXP3 gene expression in cord blood and decreased placental FOXP3 protein expression. Low placental FOXP3 protein was related with activating PI3K/AKT/mTOR signaling pathway.

Canonical and Nuclear mTOR Specify Distinct Transcriptional Programs in Androgen-Dependent Prostate Cancer Cells

mTOR is a serine/threonine kinase that controls prostate cancer cell growth in part by regulating gene programs associated with metabolic and cell proliferation pathways. mTOR-mediated control of gene expression can be achieved via phosphorylation of transcription factors, leading to changes in their cellular localization and activities. mTOR also directly associates with chromatin in complex with transcriptional regulators, including the androgen receptor (AR). Nuclear mTOR (nmTOR) has been previously shown to act as a transcriptional integrator of the androgen signaling pathway in association with the chromatin remodeling machinery, AR, and FOXA1. However, the contribution of cytoplasmic mTOR (cmTOR) and nmTOR and the role played by FOXA1 in this process remains to be explored. Herein, we engineered cells expressing mTOR tagged with nuclear localization and export signals dictating mTOR localization. Transcriptome profiling in AR-positive prostate cancer cells revealed that nmTOR generally downregulates a subset of the androgen response pathway independently of its kinase activity, while cmTOR upregulates a cell cycle-related gene signature in a kinase-dependent manner. Biochemical and genome-wide transcriptomic analyses demonstrate that nmTOR functionally interacts with AR and FOXA1. Ablation of FOXA1 reprograms the nmTOR cistrome and transcriptome of androgen responsive prostate cancer cells. This works highlights a transcriptional regulatory pathway in which direct interactions between nmTOR, AR and FOXA1 dictate a combinatorial role for these factors in the control of specific gene programs in prostate cancer cells.

IMPLICATIONS

The finding that canonical and nuclear mTOR signaling pathways control distinct gene programs opens therapeutic opportunities to modulate mTOR activity in prostate cancer cells.

Akt activation ameliorates deficits in hippocampal-dependent memory and activity-dependent synaptic protein synthesis in an Alzheimer's disease mouse model

Protein kinase-B (Akt) and the mechanistic target of rapamycin (mTOR) signaling pathways are implicated in Alzheimer's disease (AD) pathology. Akt/mTOR signaling pathways, activated by external inputs, enable new protein synthesis at the synapse and synaptic plasticity. The molecular mechanisms impeding new protein synthesis at the synapse in AD pathogenesis remain elusive. Here, we aimed to understand the molecular mechanisms prior to the manifestation of histopathological hallmarks by characterizing Akt1/mTOR signaling cascades and new protein synthesis in the hippocampus of WT and amyloid precursor protein/presenilin-1 (APP/PS1) male mice. Intriguingly, compared to those in WT mice, we found significant decreases in pAkt1, pGSK3β, pmTOR, pS6 ribosomal protein, and p4E-BP1 levels in both post nuclear supernatant and synaptosomes isolated from the hippocampus of one-month-old (presymptomatic) APP/PS1 mice. In synaptoneurosomes prepared from the hippocampus of presymptomatic APP/PS1 mice, activity-dependent protein synthesis at the synapse was impaired and this deficit was sustained in young adults. In hippocampal neurons from C57BL/6 mice, downregulation of Akt1 precluded synaptic activity-dependent protein synthesis at the dendrites but not in the soma. In three-month-old APP/PS1 mice, Akt activator (SC79) administration restored deficits in memory recall and activity-dependent synaptic protein synthesis. C57BL/6 mice administered with an Akt inhibitor (MK2206) resulted in memory recall deficits compared to those treated with vehicle. We conclude that dysregulation of Akt1/mTOR and its downstream signaling molecules in the hippocampus contribute to memory recall deficits and loss of activity-dependent synaptic protein synthesis. In AD mice, however, Akt activation ameliorates deficits in memory recall and activity-dependent synaptic protein synthesis.

[Total polyphenols of Cydonia oblonga inhibited proliferation and migration of renal cancer cells by PI3K/Akt/mTOR pathway]

The mechanism of total polyphenols of Cydonia oblonga Miller(TPCOM) against kidney cancer was elucidated through a combination of network pharmacology, bioinformatics, and experimental verification. The active polyphenolic compounds from C. oblonga were screened by network pharmacological techniques and kidney cancer-related targets were collected through the database. The differential gene expression analysis was performed on RNA sequencing data from tumor tissue and normal tissue of kidney cancer patients obtained from the Gene Expression Omnibus(GEO) database. The results of network pharmacology predictions and differential gene expression analysis were used to identify the core genes targeted by TPCOM in kidney cancer. Survival analysis was conducted to identify key targets that could impact patient survival, followed by Kyoto Encyclopedia of Genes and Genomes(KEGG) and Gene Ontology(GO) enrichment analyses. Cell proliferation and activity experiments(cell counting kit-8) were conducted using TPCOM at concentrations ranging from 20 to 640 μg·mL~(-1) on 786-O and Renca cells. Additionally, TPCOM at concentrations of 40, 80, and 160 μg·mL~(-1) was applied to kidney cancer cells to assess its effect on cell migration and its regulation of protein expression levels related to the protein kinase B(Akt), mammalian target of rapamycin(mTOR), and phosphoinositide 3-kinase(PI3K) signaling pathways. Network pharmacology predicted eight active polyphenolic compounds from C. oblonga. Survival analysis revealed 15 significantly differentially expressed genes in kidney cancer that were affected by TPCOM and had a significant impact on patient survival. KEGG and GO analysis results indicated that these 15 targets were primarily associated with the PI3K/Akt signaling pathway, cell migration, and proliferation. The results showed that TPCOM could inhibit the proliferation of 786-O and Renca cells, with IC_(50) values of 121.4 and 137.9 μg·mL~(-1), respectively. TPCOM was also found to inhibit the migration of these cells and suppress the PI3K/Akt/mTOR signaling pathway. TPCOM may exert its anti-kidney cancer effects by inhibiting the activation of the PI3K/Akt/mTOR signaling pathway, thereby restraining the proliferation and migration of kidney cancer cells. This study provides a foundation for the research on the anti-tumor effects of natural product C. oblonga, particularly in Xinjiang, and holds significance for further promoting its development and utilization.

Multiomic profiling reveals metabolic alterations mediating aberrant platelet activity and inflammation in myeloproliferative neoplasms

Platelets from patients with myeloproliferative neoplasms (MPNs) exhibit a hyperreactive phenotype. Here, we found elevated P-selectin exposure and platelet-leukocyte aggregates indicating activation of platelets from essential thrombocythemia (ET) patients. Single-cell RNA-seq analysis of primary samples revealed significant enrichment of transcripts related to platelet activation, mTOR, and oxidative phosphorylation in ET patient platelets. These observations were validated via proteomic profiling. Platelet metabolomics revealed distinct metabolic phenotypes consisting of elevated ATP generation accompanied by increases in the levels of multiple intermediates of the tricarboxylic acid cycle, but lower α-ketoglutarate (α-KG) in MPN patients. Inhibition of PI3K/AKT/mTOR signaling significantly reduced metabolic responses and hyperreactivity in MPN patient platelets, while α-KG supplementation markedly reduced oxygen consumption and ATP generation. Ex vivo incubation of platelets from both MPN patients and Jak2 V617F-knockin mice with α-KG supplementation significantly reduced platelet activation responses. Oral α-KG supplementation of Jak2 V617F mice decreased splenomegaly and reduced hematocrit, monocyte, and platelet counts. Finally, α-KG treatment significantly decreased proinflammatory cytokine secretion from MPN CD14+ monocytes. Our results reveal a previously unrecognized metabolic disorder in conjunction with aberrant PI3K/AKT/mTOR signaling that contributes to platelet hyperreactivity in MPN patients.

Cerebral vascular and blood brain-barrier abnormalities in a mouse model of epilepsy and tuberous sclerosis complex

OBJECTIVE

Tuberous sclerosis complex (TSC) is a genetic disorder, characterized by tumor formation in the brain and other organs, and severe neurological symptoms, such as epilepsy. Abnormal vascular endothelial growth factor (VEGF) expression may promote angiogenesis in kidney and lung tumors in TSC and has been identified in brain specimens from TSC patients, but the role of VEGF and vascular abnormalities in neurological manifestations of TSC is poorly defined. In this study, we investigated abnormalities in brain VEGF expression, cerebral blood vessel anatomy, and blood-brain barrier (BBB) structure and function in a mouse model of TSC.

METHODS

Tsc1GFAP CKO mice were used to investigate VEGF expression and vascular abnormalities in the brain by Western blotting and immunohistochemical analysis of vascular and BBB markers. In vivo two-photon imaging was used to assess BBB permeability to normally impenetrable fluorescently labeled compounds. The effect of mechanistic target of rapamycin (mTOR) pathway inhibitors, VEGF receptor antagonists (apatinib), or BBB stabilizers (RepSox) was assessed in some of these assays, as well as on seizures by video-electroencephalography.

RESULTS

VEGF expression was elevated in cortex of Tsc1GFAP CKO mice, which was reversed by the mTOR inhibitor rapamycin. Tsc1GFAP CKO mice exhibited increased cerebral angiogenesis and vascular complexity in cortex and hippocampus, which were reversed by the VEGF receptor antagonist apatinib. BBB permeability was abnormally increased and BBB-related tight junction proteins occludin and claudin-5 were decreased in Tsc1GFAP CKO mice, also in an apatinib- and RepSox-dependent manner. The BBB stabilizer (RepSox), but not the VEGF receptor antagonist (apatinib), decreased seizures and improved survival in Tsc1GFAP CKO mice.

SIGNIFICANCE

Increased brain VEGF expression is dependent on mTOR pathway activation and promotes cerebral vascular abnormalities and increased BBB permeability in a mouse model of TSC. BBB modulation may affect epileptogenesis and represent a rational treatment for epilepsy in TSC.

Caffeic acid 3,4-dihydroxyphenethyl ester prevents colorectal cancer through inhibition of multiple cancer-promoting signal pathways in 1,2-Dimethylhydrazine/dextran sodium sulphate mouse model

OBJECTIVE

To elucidate the potential feature and mechanism of the caffeic acid 3,4-dihydroxyphenethyl ester (CADPE) molecule, which can prevent colorectal cancer (CRC) in the 1,2-Dimethylhydrazine (DMH)/dextran sodium sulphate (DSS)-induced mouse model.

METHODS

Institute of cancer research (ICR) male mice were injected with 20 mg/kg DMH for a week. After that, 2% DSS was administered in the drinking water for another 7 d. The CADPE treatment was given to the DMH/DSS induced male mice at three different periods until their sacrifice. Histopathological examination was used for observing the CRC development at colonic mucosa. Immunohistochemistry (IHC), blood cells smearing and crypt damage scoring methods were used for investigating the anti-inflammation feature of CADPE related to CRC. The reversing targets searching method was applied with artificial intelligence (AI), computer-aided drug designing (CADD) and Ingenuity Pathway Analysis (IPA) techniques for predicting the potential targets and mechanism of CADPE highly related to CRC.

RESULTS

The data indicated that CADPE inhibited CRC tumor development in the colitis-associated DMH/DSS induced mouse model after giving the early treatment. CADPE also impeded the acute inflammation by decreasing the infiltration of neutrophils significantly during the initial stage of CRC development. Finally, our data showed that CADPE prevented CRC by blocking active sites of three pivotal protein targets including epidermal growth factor receptor (EGFR), extracellular signal-regulated kinase (ERK) and mammalian target of rapamycin (mTOR) in two major cancer development pathways.

CONCLUSIONS

CADPE effectively prevented CRC at early stage of tumor germination in the DMH/DSS mouse model highly likely due to its anti-acute inflammation characteristic and the ability of blocking EGFR, ERK and mTOR activities in two highly related CRC developing pathways.

Anti-seizure gene therapy for focal cortical dysplasia

Focal cortical dysplasias are a common subtype of malformation of cortical development, which frequently presents with a spectrum of cognitive and behavioural abnormalities as well as pharmacoresistant epilepsy. Focal cortical dysplasia type II is typically caused by somatic mutations resulting in mammalian target of rapamycin (mTOR) hyperactivity, and is the commonest pathology found in children undergoing epilepsy surgery. However, surgical resection does not always result in seizure freedom, and is often precluded by proximity to eloquent brain regions. Gene therapy is a promising potential alternative treatment and may be appropriate in cases that represent an unacceptable surgical risk. Here, we evaluated a gene therapy based on overexpression of the Kv1.1 potassium channel in a mouse model of frontal lobe focal cortical dysplasia. An engineered potassium channel (EKC) transgene was placed under control of a human promoter that biases expression towards principal neurons (CAMK2A) and packaged in an adeno-associated viral vector (AAV9). We used an established focal cortical dysplasia model generated by in utero electroporation of frontal lobe neural progenitors with a constitutively active human Ras homolog enriched in brain (RHEB) plasmid, an activator of mTOR complex 1. We characterized the model by quantifying electrocorticographic and behavioural abnormalities, both in mice developing spontaneous generalized seizures and in mice only exhibiting interictal discharges. Injection of AAV9-CAMK2A-EKC in the dysplastic region resulted in a robust decrease (∼64%) in the frequency of seizures. Despite the robust anti-epileptic effect of the treatment, there was neither an improvement nor a worsening of performance in behavioural tests sensitive to frontal lobe function. AAV9-CAMK2A-EKC had no effect on interictal discharges or behaviour in mice without generalized seizures. AAV9-CAMK2A-EKC gene therapy is a promising therapy with translational potential to treat the epileptic phenotype of mTOR-related malformations of cortical development. Cognitive and behavioural co-morbidities may, however, resist an intervention aimed at reducing circuit excitability.

Osteocalcin activates lipophagy via the ADPN-AMPK/PPARα-mTOR signaling pathway in chicken embryonic hepatocyte

Fatty liver hemorrhage syndrome (FLHS) is the leading cause of noninfectious mortality in caged layers worldwide. Osteocalcin (OCN) is a protein secreted by osteoblasts, and its undercarboxylated form (ucOCN) acts as a multifunctional hormone that protects laying hens from FLHS. Lipophagy is a form of selective autophagy that breaks down lipid droplets (LDs) through lysosomes, and defective lipophagy is associated with FLHS. The aim of this study was to investigate the effects of ucOCN on the lipophagy of chicken embryonic hepatocytes and associated the function of the adiponectin (ADPN) signaling pathway. In this study, chicken embryonic hepatocytes were divided into 5 groups: control (CONT), fat emulsion (FE, 10% FE, v/v), FE with ucOCN at 1 ng/mL (FE-LOCN), 3 ng/mL (FE-MOCN), and 9 ng/mL (FE-HOCN). In addition, 4 μM AdipoRon, an adiponectin receptor agonist, was used to investigate the function of ADPN. The results showed that compared with CONT group, FE promoted the levels of phosphorylation of mammalian target of rapamycin (p-mTOR) (P < 0.05) and decreased the mRNA expression of ADNP receptors (AdipoR1 and AdipoR2). Compared with FE group, 3 and 9 ng/mL ucOCN inhibited the levels of autophagy adaptor p62 and p-mTOR (P < 0.05), increased the ratios of LC3-II/LC3-I (P < 0.05) and phosphorylated adenosine 5'-monophosphate-activated protein kinase (p-AMPK)/AMPK (P < 0.05), as well as the levels of peroxisome proliferator-activated receptor α (PPAR-α) and ADPN (P < 0.05). In addition, ucOCN at the tested concentrations increased the colocalization of LC3 and LDs in fatty hepatocytes. Administrated 4 μM AdipoRon activated AdipoR1 and AidpoR2 mRNA expression (P < 0.05), decreased the concentrations of triglyceride (P < 0.05), without effects on cell viability (P > 0.05). AdipoRon also increased the LC3-II/LC3-I ratio (P < 0.05) and the levels of p-AMPK/AMPK and PPAR-α (P < 0.05). In conclusion, the results reveal that ucOCN regulates lipid metabolism by activating lipophagy via the ADPN-AMPK/PPARα-mTOR signaling pathway in chicken embryonic hepatocytes. The results may provide new insights for controlling FLHS in laying hens.

Methionine Promotes Milk Synthesis through the BRCC36-BRG1-mTOR Signaling Axis in Mammary Epithelial Cells

Methionine (Met) functions as a key stimulator on the mTOR signaling pathway and milk synthesis, but the molecular mechanism remains incompletely understood. We investigated the regulatory roles of BRCC36 in Met-stimulated milk lipid and protein synthesis, cell proliferation, and the mTOR signaling pathway. Knockdown of BRCC36 promoted milk lipid and protein synthesis in HC11 cells as well as cell proliferation by increasing the levels of mTOR gene transcription and protein phosphorylation. Conversely, the gene activation of BRCC36 had opposite effects. Furthermore, BRCC36 gene activation completely blocked Met stimulation on the BRG1 protein level and mTOR mRNA level and protein phosphorylation. BRCC36 bound to BRG1, and BRCC36 and BRG1 bound to the same region on the mTOR promoter. BRCC36 inhibited the BRG1 protein level and the binding of BRG1 to the mTOR promoter. Met decreased the BRCC36 protein level, and this effect was significantly attenuated by MG132 but not affected by cycloheximide or chloroquine. We further showed that Met increased BRCC36 ubiquitination degradation. Our findings reveal that Met promotes milk lipid and protein synthesis in MECs through the BRCC36-BRG1-mTOR signaling axis.

Exosomal circMACF1 drives PI3K/AKT/mTOR-mediated autophagy suppression in laryngeal squamous cell carcinoma

Laryngeal squamous cell carcinoma (LSCC) is a common malignant tumor. The regulatory functions of circular RNAs (circRNAs) in cancers have been broadly reported. The hsa_circ_0011773 (circMACF1) is reported to be overexpressed in LSCC tissues, while its biological function in LSCC remains unclear. CircMACF1 expression in LSCC tissues and cells was assessed via RT-qPCR. Exosomes extracted from cells were identified by TEM and NTA. Autophagy-related proteins were tested by western blot. Confocal microscope was employed for analyzing LC3 expression. Cell proliferation, migration, and invasion were assessed by CCK-8 assay and transwell assay. The levels of main proteins on PI3K/AKT/mTOR were tested by western blot. We observed that circMACF1 was highly expressed in LSCC tissues and cells. Furthermore, circMACF1 expression was also upregulated in the exosomes derived from LSCC cells. CircMACF1 depletion promoted LC3 expression in cells. Additionally, we proved that circMACF1 knockdown suppressed LSCC cell proliferative, migratory and invasive capabilities via promoting autophagy. Exosomal circMACF1 was found to promote LSCC tumor growth. Then, we proved that circMACF1 could activate PI3K/AKT/mTOR pathway to regulate autophagy. Moreover, MACF1 was positively regulated by circMACF1 and its overexpression notably reversed the effects of circMACF1 depletion in LSCC progression. Exosomal circMACF1 can regulate PI3K/AKT/mTOR-mediated autophagy suppression to facilitate LSCC development.

The mTORC2 signaling network: targets and cross-talks

The mechanistic target of rapamycin, mTOR, controls cell metabolism in response to growth signals and stress stimuli. The cellular functions of mTOR are mediated by two distinct protein complexes, mTOR complex 1 (mTORC1) and mTORC2. Rapamycin and its analogs are currently used in the clinic to treat a variety of diseases and have been instrumental in delineating the functions of its direct target, mTORC1. Despite the lack of a specific mTORC2 inhibitor, genetic studies that disrupt mTORC2 expression unravel the functions of this more elusive mTOR complex. Like mTORC1 which responds to growth signals, mTORC2 is also activated by anabolic signals but is additionally triggered by stress. mTORC2 mediates signals from growth factor receptors and G-protein coupled receptors. How stress conditions such as nutrient limitation modulate mTORC2 activation to allow metabolic reprogramming and ensure cell survival remains poorly understood. A variety of downstream effectors of mTORC2 have been identified but the most well-characterized mTORC2 substrates include Akt, PKC, and SGK, which are members of the AGC protein kinase family. Here, we review how mTORC2 is regulated by cellular stimuli including how compartmentalization and modulation of complex components affect mTORC2 signaling. We elaborate on how phosphorylation of its substrates, particularly the AGC kinases, mediates its diverse functions in growth, proliferation, survival, and differentiation. We discuss other signaling and metabolic components that cross-talk with mTORC2 and the cellular output of these signals. Lastly, we consider how to more effectively target the mTORC2 pathway to treat diseases that have deregulated mTOR signaling.

The HIF-1α and mTOR Pathways Amplify Heterotopic Ossification

Fibrodysplasia ossificans progressiva (FOP; MIM# 135100) is an ultra-rare congenital disorder caused by gain-of-function point mutations in the Activin receptor A type I (ACVR1, also known as ALK2) gene. FOP is characterized by episodic heterotopic ossification (HO) in skeletal muscles, tendons, ligaments, or other soft tissues that progressively causes irreversible loss of mobility. FOP mutations cause mild ligand-independent constitutive activation as well as ligand-dependent bone morphogenetic protein (BMP) pathway hypersensitivity of mutant ACVR1. BMP signaling is also a key pathway for mediating acquired HO. However, HO is a highly complex biological process involving multiple interacting signaling pathways. Among them, the hypoxia-inducible factor (HIF) and mechanistic target of rapamycin (mTOR) pathways are intimately involved in both genetic and acquired HO formation. HIF-1α inhibition or mTOR inhibition reduces HO formation in mouse models of FOP or acquired HO in part by de-amplifying the BMP pathway signaling. Here, we review the recent progress on the mechanisms of the HIF-1α and mTOR pathways in the amplification of HO lesions and discuss the future directions and strategies to translate the targeting of HIF-1α and the mTOR pathways into clinical interventions for FOP and other forms of HO.