Raptor, a binding partner of target of rapamycin (TOR), mediates TOR action

Genome-wide association study on overweight in Brazilian children with asthma: Old stories and new discoveries

INTRODUCTION

Overweight and obesity are chronic and multifactorial diseases with a strong genetic component contributing to weight gain across all age groups. This study aimed to conduct a Genome-wide Association Study (GWAS) on a cohort of 1,004 Brazilian children (5-11 years old) to identify specific DNA regions associated with susceptibility to overweight.

METHODS

The GWAS was performed on children participating in the SCAALA (Asthma and Allergy Social Changes in Latin America) program, with participants classified as either overweight or non-overweight. Genotyping was carried out using the Illumina 2.5 Human Omni bead chip. Using ELISA, cytokine levels (IL-5, IL-13, IL-10, and IFN) were measured in the blood culture supernatant. Furthermore, pathway analyses were conducted utilizing the Gene Ontology tool.

RESULTS

Our analysis revealed eight significant signals distributed across the genome. The most prominent single nucleotide variant (SNV) was identified in the IL1R1 gene, followed by three variants in the LOC105377841 region (located between the ADH5P4 and EYS genes), as well as variants in the KNTC1, RAPTOR, and DSCAM genes. Among the identified variants, three (IL1R1, RAPTOR, and DSCAM) are associated with immune mechanisms, one (ST18) is linked to the death pathway, and one (KNTC1) is associated with mitotic spindle assembly. The genetic risk score analysis demonstrated that having one or more variants among the six analyzed significantly increased the risk of being overweight by eightfold.

CONCLUSIONS

Our study uncovered genetic loci within pathways with strong biological plausibility, including identifying a novel region (LOC105377841) not previously associated with overweight. Understanding the genetic variants involved in overweight and obesity is crucial for advancing our knowledge of these diseases, particularly within mixed populations such as the Brazilian population.

PTEN mutations impair CSF dynamics and cortical networks by dysregulating periventricular neural progenitors

Enlargement of the cerebrospinal fluid (CSF)-filled brain ventricles (ventriculomegaly) is a defining feature of congenital hydrocephalus (CH) and an under-recognized concomitant of autism. Here, we show that de novo mutations in the autism risk gene PTEN are among the most frequent monogenic causes of CH and primary ventriculomegaly. Mouse Pten-mutant ventriculomegaly results from aqueductal stenosis due to hyperproliferation of periventricular Nkx2.1+ neural progenitor cells (NPCs) and increased CSF production from hyperplastic choroid plexus. Pten-mutant ventriculomegalic cortices exhibit network dysfunction from increased activity of Nkx2.1+ NPC-derived inhibitory interneurons. Raptor deletion or postnatal everolimus treatment corrects ventriculomegaly, rescues cortical deficits and increases survival by antagonizing mTORC1-dependent Nkx2.1+ NPC pathology. Thus, PTEN mutations concurrently alter CSF dynamics and cortical networks by dysregulating Nkx2.1+ NPCs. These results implicate a nonsurgical treatment for CH, demonstrate a genetic association of ventriculomegaly and ASD, and help explain neurodevelopmental phenotypes refractory to CSF shunting in select individuals with CH.

Behavioral analyses in rodent models of tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is typically associated with epilepsy, but patients also present with a myriad of comorbid neuropsychiatric disorders. TSC is caused by mutations in the tuberous sclerosis complex genes 1 or 2 (TSC1, TSC2). This TSC1/2 complex serves as a negative regulator of the mammalian target of rapamycin (mTOR) signaling pathway, which plays a crucial role in regulating neuronal function, including cell proliferation, survival, growth, and protein synthesis. Mutations result in hyperactivation of the pathway. Animal models with mutations in Tsc1 or Tsc2 consistently exhibit epilepsy and behavioral phenotypes. Additionally, abnormal neuronal populations can impact the broader network, leading to deficits in learning and memory, anxiety-like behaviors, deficits in social behaviors, and perseverative and repetitive behaviors. This review aims to synthesize the existing animal literature linking TSC models to epileptogenesis and behavioral impairments, with insights on how modifications in TSC signaling influence both the structure and function of neurons and behavior. Understanding these relationships may provide valuable insights into potential therapeutic targets for managing epilepsy and neuropsychiatric disorders associated with TSC dysregulation.

A gain-of-function variant in RICTOR predisposes to human obesity

mTORC1/2 play central roles as signaling hubs of cell growth and metabolism and are therapeutic targets for several diseases. However, the human genetic evidence linking mutations of mTORC1/2 to obesity remains elusive. Using whole-exome sequencing of 1,944 cases with severe obesity and 2,161 healthy lean controls, we identify a rare RICTOR p.I116V variant enriched in 9 unrelated cases. In Rictor null mouse embryonic fibroblasts, overexpression of the RICTOR p.I116V mutant increases phosphorylation of AKT, a canonical mTORC2 substrate, compared to wild-type RICTOR, indicating a gain-of-function change. Consistent with the human obesity phenotype, the knock-in mice carrying homogenous Rictor p.I116V variants gain more body weight under a high-fat diet. Additionally, the stromal vascular fraction cells derived from inguinal white adipose tissue of knock-in mice display an enhanced capacity for adipocyte differentiation via AKT activity. These findings illustrate that the rare gain-of-function RICTOR p.I116V mutation activates AKT signaling, promotes adipogenesis, and contributes to obesity in humans.

Targeting mTOR with curcumin: therapeutic implications for complex diseases

The mammalian target of rapamycin (mTOR) is a crucial enzyme in regulating multiple signaling pathways in the body, including autophagy, proliferation and apoptosis. Disruption of these mTOR signaling pathways can lead to an array of abnormalities and trigger disease processes, examples being neurodegenerative conditions, cancer, obesity and diabetes. Under conditions of oxidative stress, mTOR can regulate apoptosis and autophagy, with tissue repair being favored under such circumstances. Moreover, the correlation between mTOR and other signaling pathways could play a pivotal role in the pathophysiology of numerous disorders. mTOR has a tight connection with NF-κB, Akt, PI3K, MAPK, GSK-3β, Nrf2/HO-1, JAK/STAT, CREB/BDNF, and ERK1/2 pathways, which together could play significant roles in the regulation of inflammation, apoptosis, cell survival, and oxidative stress in different body organs. Research suggests that inhibiting mTOR could be beneficial in treating metabolic, neurological and cardiovascular conditions, as well as potentially extending life expectancy. Therefore, identifying new chemicals and agents that can modulate the mTOR signaling pathway holds promise for treating and preventing these disorders. Curcumin is one such agent that has demonstrated regulatory effects on the mTOR pathway, making it an exciting alternative for reducing complications associated with complex diseases by targeting mTOR. This review aims to examine the potential of curcumin in modulating the mTOR signaling pathway and its therapeutic implications.

Buddleoside alleviates nonalcoholic steatohepatitis by targeting the AMPK-TFEB signaling pathway

Nonalcoholic steatohepatitis (NASH) is a combination of hepatic steatosis, inflammation, and fibrosis, and it often follows simple hepatic steatosis in nonalcoholic fatty liver disease (NAFLD). However, no pharmacological treatment is currently available for NASH. Given the important role of TFEB (transcription factor EB) in regulating the macroautophagy/autophagy-lysosomal pathway, TFEB is potentially a novel therapeutic target for treatment of NASH, which function can be regulated by AMP-activated protein kinase (AMPK) and MTOR (mechanistic target of rapamycin kinase) complex 1 (MTORC1). Buddleoside (Bud), a natural flavonoid compound, has recently emerged as a promising drug candidate for liver diseases. Here, we shown that Bud treatment alleviated hepatic steatosis, insulin resistance, inflammation, and fibrosis in mice fed a high-fat and high-cholesterol (HFHC) diet. Notably, Bud activated AMPK, inhibited MTORC1, and enhanced TFEB transcriptional activity as well as autophagic flux in vivo and in vitro. Inhibition of AMPK or knockout of hepatic Tfeb abrogated the alleviation effects of Bud on hepatic steatosis, insulin resistance, inflammation, and fibrosis. Mechanistic investigation revealed that Bud bound to the PRKAB1 subunit via Val81, Arg83, and Ser108 residues and activated AMPK, thereby eliciting phosphorylation of RPTOR (regulatory associated protein of MTOR complex 1) and inhibiting the kinase MTORC1, which activated the TFEB-mediated autophagy-lysosomal pathway and further ameliorated HFHC-induced NASH in mice. Altogether, our results indicate that Bud ameliorates NASH by activating hepatic the AMPK-TFEB axis, suggesting that Bud is a potential therapeutic strategy for NASH.

The mTOR Signaling Pathway: Key Regulator and Therapeutic Target for Heart Disease

Heart disease, including myocardial infarction, heart failure, cardiac hypertrophy, and cardiomyopathy, remains a leading cause of mortality worldwide. The mammalian target of rapamycin (mTOR) is a centrally regulated kinase that governs key cellular processes, including growth, proliferation, metabolism, and survival. Notably, mTOR plays a pivotal role in cardiovascular health and disease, particularly in the onset and progression of cardiac conditions. In this review, we discuss mTOR's structure and function as well as the regulatory mechanisms of its associated signaling pathways. We focus on the molecular mechanisms by which mTOR signaling regulates cardiac diseases and the potential of mTOR inhibitors and related regulatory drugs in preventing these conditions. We conclude that the mTOR signaling pathway is a promising therapeutic target for heart disease.

Bombyx mori PAT4 gene inhibits BmNPV infection and replication through autophagy

Proton-assisted amino acid transporter 4 (PAT4) is a member of the solute carrier (SLC) 36 family, which mediates the transmembrane transport of amino acids and their derivatives. However, the function of PAT4 in Bombyx mori is not clear. In this study, BmPAT4 was cloned and identified using PCR technology. Its open reading frame (ORF) includes 1,395 bp, encoding 464 amino acid (Aa). Moreover, the sequence of BmPAT4 has the highest similarity with wild Bombyx.mandarina, Spodoptera frugiperda and Spodoptera litura, and it has ten transmembrane domains. BmPAT4 was localized in the cell membrane and expressed in all tissues of the silkworm. After Bombyx mori nuclear polyhedrosis virus (BmNPV) infection, the expression of BmPAT4 in midgut, hemolymph and fat body was significantly up-regulated. In addition, overexpression of BmPAT4 in BmN cells could significantly inhibit the proliferation of BmNPV, and the expression of several genes in autophagy pathway decreased significantly. On the contrary, down-regulation of BmPAT4 expression by RNA interference can promote BmNPV replication and proliferation, and the expression of key genes in autophagy pathway is significantly increased. This is the first time to report that BmPAT4 has an antiviral effect in silkworm. Moreover, the silkworm activates BmTORC1 via BmPAT4, which inhibits autophagy in silkworm cells, resulting in a lack of energy and raw materials for BmNPV infection and replication in cells.

Atg2 controls Drosophila hematopoiesis through the PVR/TOR signaling pathways

The hematopoietic system of Drosophila is a well-established genetic model for studying hematopoiesis mechanisms, which are strictly regulated by multiple signaling pathways. Autophagy-related 2 (Atg2) protein is involved in autophagosome formation through its lipid transfer function; however, other functions in animal development, especially the role of Atg2 in maintaining hematopoietic homeostasis, are unclear. Here, we show that Atg2 knockdown in the cortical zone (CZ) induced the proliferation and differentiation of mature plasmatocytes and disrupted progenitor maintenance in the medullary zone (MZ). We also observed the differentiation of lamellocytes among circulating hemocytes and in the lymph gland, which is rarely observed in healthy larvae. The above results on hematopoiesis disorders are due to Atg2 regulating the Drosophila PDGF/VEGF receptor (PVR) and target of rapamycin (TOR) in the CZ of lymph gland. In conclusion, we identified Atg2 as a previously undescribed regulator of hematopoiesis. Understanding the mechanism of maintenance of hematopoietic homeostasis in Drosophila will help us better evaluate human blood disorder-related diseases.

Genomic insights into mRNA COVID-19 vaccines efficacy: Linking genetic polymorphisms to waning immunity

Genetic polymorphisms have been linked to the differential waning of vaccine-induced immunity against COVID-19 following vaccination. Despite this, evidence on the mechanisms behind this waning and its implications for vaccination policy remains limited. We hypothesize that specific gene variants may modulate the development of vaccine-initiated immunity, leading to impaired immune function. This study investigates genetic determinants influencing the sustainability of immunity post-mRNA vaccination through a genome-wide association study (GWAS). Utilizing a hospital-based, test negative case-control design, we enrolled 1,119 participants from the Taiwan Precision Medicine Initiative (TPMI) cohort, all of whom completed a full mRNA COVID-19 vaccination regimen and underwent PCR testing during the Omicron outbreak. Participants were classified into breakthrough and protected groups based on PCR results. Genetic samples were analyzed using SNP arrays with rigorous quality control. Cox regression identified significant single nucleotide polymorphisms (SNPs) associated with breakthrough infections, affecting 743 genes involved in processes such as antigenic protein translation, B cell activation, and T cell function. Key genes identified include CD247, TRPV1, MYH9, CCL16, and RPTOR, which are vital for immune responses. Polygenic risk score (PRS) analysis revealed that individuals with higher PRS are at greater risk of breakthrough infections post-vaccination, demonstrating a high predictability (AUC = 0.787) in validating population. This finding confirms the significant influence of genetic variations on the durability of immune responses and vaccine effectiveness. This study highlights the importance of considering genetic polymorphisms in evaluating vaccine-induced immunity and proposes potential personalized vaccination strategies by tailoring regimens to individual genetic profiles.

Targeting mTOR Kinase with Natural Compounds: Potent ATP-Competitive Inhibition Through Enhanced Binding Mechanisms

Background/Objectives: The mammalian target of the rapamycin (mTOR) signaling pathway is a central regulator of cell growth, proliferation, metabolism, and survival. Dysregulation of mTOR signaling contributes to many human diseases, including cancer, diabetes, and obesity. Therefore, inhibitors against mTOR's catalytic kinase domain (KD) have been developed and have shown significant antitumor activities, making it a promising therapeutic target. The ATP-KD interaction is particularly important for mTOR to exert its cellular functions, and such inhibitors have demonstrated efficient attenuation of overall mTOR activity. Methods: In this study, we screened the Traditional Chinese Medicine (TCM) database, which enlists natural products that capture the relationships between drugs targets and diseases. Our aim was to identify potential ATP-competitive agonists that target the mTOR-KD and compete with ATP to bind the mTOR-KD serving as potential potent mTOR inhibitors. Results: We identified two compounds that demonstrated interatomic interactions similar to those of ATP-mTOR. The conformational stability and dynamic features of the mTOR-KD bound to the selected compounds were tested by subjecting each complex to 200 ns molecular dynamic (MD) simulations and molecular mechanics/generalized Born surface area (MM/GBSA) to extract free binding energies. We show the effectiveness of both compounds in forming stable complexes with the mTOR-KD, which is more effective than the mTOR-KD-ATP complex with more robust binding affinities. Conclusions: This study implies that both compounds could serve as potential therapeutic inhibitors of mTOR, regulating its function and, therefore, mitigating human disease progression.

Physiological and Pathological Role of mTOR Signaling in Astrocytes

The mammalian target of rapamycin (mTOR) signaling pathway is one of the key regulators of cellular energy metabolism. It senses diverse alterations in the extracellular environment such as availability of nutrients and growth factors, and mediates the corresponding intracellular response. In the brain, astrocytes crucially contribute to energy and neurotransmitter metabolism, and numerous other functions. However, the relevance of physiological, astrocytic mTOR signaling in maintaining brain homeostasis and function is not well understood. Pathophysiological mTOR signaling is involved in manifold diseases in the central nervous system and most of the knowledge about astrocytic mTOR signaling has been derived from observations on these disorders. Dysregulation of the mTOR signaling pathway impairs important functions of astrocytes including neurotransmitter uptake and -signaling as well as energy metabolism. Some of these alterations could trigger neuropathological conditions such as epilepsy. This review focuses on how mTOR signaling regulates properties of astrocytes, and how these signaling events might contribute to the physiological function of the brain.

Identification and functional characterisation of DNA methylation differences between East- and West-originating Finns

Eastern and Western Finns show a striking difference in coronary heart disease-related mortality; genetics is a known contributor for this discrepancy. Here, we discuss the potential role of DNA methylation in mediating the discrepancy in cardiometabolic disease-risk phenotypes between the sub-populations. We used data from the Young Finns Study (n = 969) to compare the genome-wide DNA methylation levels of East- and West-originating Finns. We identified 21 differentially methylated loci (FDR < 0.05; Δβ >2.5%) and 7 regions (smoothed FDR < 0.05; CpGs ≥ 5). Methylation at all loci and regions associates with genetic variants (p < 5 × 10-8). Independently of genetics, methylation at 11 loci and 4 regions associates with transcript expression, including genes encoding zinc finger proteins. Similarly, methylation at 5 loci and 4 regions associates with cardiometabolic disease-risk phenotypes including triglycerides, glucose, cholesterol, as well as insulin treatment. This analysis was also performed in LURIC (n = 2371), a German cardiovascular patient cohort, and results replicated for the association of methylation at cg26740318 and DMR_11p15 with diabetes-related phenotypes and methylation at DMR_22q13 with triglyceride levels. Our results indicate that DNA methylation differences between East and West Finns may have a functional role in mediating the cardiometabolic disease discrepancy between the sub-populations.

Beclin-1: a therapeutic target at the intersection of autophagy, immunotherapy, and cancer treatment

The significant identification of Beclin-1's function in regulating autophagy flow signified a significant progression in our understanding of cellular operations. Beclin-1 acts as a scaffold for forming the PI3KC3 complex, controlling autophagy and cellular trafficking processes in a complicated way. This intricate protein has garnered considerable attention due to its substantial impact on the development of tumors. Strong evidence indicates Beclin-1 plays a critical role in controlling autophagy in various human cancer types and its intricate connection with apoptosis and ferroptosis. The potential of Beclin-1 as a viable target for cancer therapy is highlighted by its associations with key autophagy regulators such as AMPK, mTOR, and ATGs. Beclin-1 controls the growth and dissemination of tumors by autophagy. It also affects how tumors react to therapies such as chemotherapy and radiation therapy. The role of Beclin-1 in autophagy can influence apoptosis, depending on whether it supports cell survival or leads to cell death. Beclin-1 plays a crucial role in ferroptosis by increasing ATG5 levels, which in turn promotes autophagy-triggered ferroptosis. Finally, we analyzed the possible function of Beclin-1 in tumor immunology and drug sensitivity in cancers. In general, Beclin-1 has a significant impact on regulating autophagy, offering various potentials for medical intervention and altering our understanding of cancer biology.

Mitochondrial Quality Control in Alzheimer's Disease: Insights from Caenorhabditis elegans Models

Alzheimer's disease (AD) is a complex neurodegenerative disorder that is classically defined by the extracellular deposition of senile plaques rich in amyloid-beta (Aβ) protein and the intracellular accumulation of neurofibrillary tangles (NFTs) that are rich in aberrantly modified tau protein. In addition to aggregative and proteostatic abnormalities, neurons affected by AD also frequently possess dysfunctional mitochondria and disrupted mitochondrial maintenance, such as the inability to eliminate damaged mitochondria via mitophagy. Decades have been spent interrogating the etiopathogenesis of AD, and contributions from model organism research have aided in developing a more fundamental understanding of molecular dysfunction caused by Aβ and toxic tau aggregates. The soil nematode C. elegans is a genetic model organism that has been widely used for interrogating neurodegenerative mechanisms including AD. In this review, we discuss the advantages and limitations of the many C. elegans AD models, with a special focus and discussion on how mitochondrial quality control pathways (namely mitophagy) may contribute to AD development. We also summarize evidence on how targeting mitophagy has been therapeutically beneficial in AD. Lastly, we delineate possible mechanisms that can work alone or in concert to ultimately lead to mitophagy impairment in neurons and may contribute to AD etiopathology.

Nutrient sensing of mTORC1 signaling in cancer and aging

The mechanistic target of rapamycin complex 1 (mTORC1) is indispensable for preserving cellular and organismal homeostasis by balancing the anabolic and catabolic processes in response to various environmental cues, such as nutrients, growth factors, energy status, oxygen levels, and stress. Dysregulation of mTORC1 signaling is associated with the progression of many types of human disorders including cancer, age-related diseases, neurodegenerative disorders, and metabolic diseases. The way mTORC1 senses various upstream signals and converts them into specific downstream responses remains a crucial question with significant impacts for our perception of the related physiological and pathological process. In this review, we discuss the recent molecular and functional insights into the nutrient sensing of the mTORC1 signaling pathway, along with the emerging role of deregulating nutrient-mTORC1 signaling in cancer and age-related disorders.

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.

Hydrogen peroxide modulates the expression of the target of rapamycin (TOR) and cell division in Arabidopsis thaliana

Hydrogen peroxide (H2O2) is naturally produced by plant cells during normal development and serves as a messenger that regulates cell metabolism. Despite its importance, the relationship between hydrogen peroxide and the target of rapamycin (TOR) pathway, as well as its impact on cell division, has been poorly analyzed. In this study, we explore the interaction of H2O2 with TOR, a serine/threonine protein kinase that plays a central role in controlling cell growth, size, and metabolism in Arabidopsis thaliana. By applying two concentrations of H2O2 exogenously (0.5 and 1 mM), we could correlate developmental traits, such as primary root growth, lateral root formation, and fresh weight, with the expression of the cell cycle gene CYCB1;1, as well as TOR expression. When assessing the expression of the ribosome biogenesis-related gene RPS27B, an increase of 94.34% was noted following exposure to 1 mM H2O2 treatment. This increase was suppressed by the TOR inhibitor torin 2. The elimination of H2O2 accumulation with ascorbic acid (AA) resulted in decreased cell division as well as TOR expression. The potential molecular mechanisms associated with the effects of H2O2 on the cell cycle and TOR expression in roots are discussed in the context of the results.

The Role of mTOR in Mycobacterium tuberculosis Infection

Background/Objectives: Mycobacterium tuberculosis (M. tb) is a pathogen that causes tuberculosis (TB), an extremely infectious disease which is responsible for millions of deaths worldwide. The severity of this pathogen is further amplified with the emergence of multidrug-resistant strains that are becoming more prevalent at an alarming rate, and novel treatments are needed. Methods: In this paper, we discuss the pathology M. tb infection. We review the literature on the role that mTOR plays in autophagy and the immune system as well as its impact on M. tb infection. Lastly, we discuss the current therapies targeting mTOR and potential routes to explore for future treatments. Results: The mTOR protein acts as a negative regulator of the autophagy pathway and presents as a potent target to establish new treatments for TB. M. tb survival is affected by mTOR, the PI3K/mTOR/AKT pathway, and autophagy. M. tb evades destruction by manipulating host cellular mechanisms, which increases resistance and complicates treatment. Conclusions: Targeting mTOR can enhance autophagy and increase M. tb clearance. Existing drugs such as everolimus, rapamycin + CC214-2, and bazedoxifene are all being currently studied for effectiveness and show positive results. Alternative therapies, including Chinese herbs, baicalin, BTLA, glutathione, and precision medicine can modulate the PI3K/mTOR/AKT pathway and the host's immune response, resulting in increased M. tb clearance, and these may be the future treatments for M. tb infection.

Dysregulating mTORC1-4E-BP2 signaling in GABAergic interneurons impairs hippocampus-dependent learning and memory

Memory formation is contingent on molecular and structural changes in neurons in response to learning stimuli-a process known as neuronal plasticity. The initiation step of mRNA translation is a gatekeeper of long-term memory by controlling the production of plasticity-related proteins in the brain. The mechanistic target of rapamycin complex 1 (mTORC1) controls mRNA translation, mainly through phosphorylation of the eukaryotic initiation factor 4E (eIF4E)-binding proteins (4E-BPs) and ribosomal protein S6 kinases (S6Ks). mTORC1 signaling decreases throughout brain development, starting from the early postnatal period. Here, we discovered that in mice, the age-dependent decrease in mTORC1 signaling occurs selectively in excitatory but not inhibitory neurons. Using a gene conditional knockout (cKO) strategy, we demonstrate that either up- or downregulating the mTORC1-4E-BP2 axis in GAD65 inhibitory interneurons, but not excitatory neurons, results in long-term object recognition and object location memory deficits. Our data indicate that the mTORC1 pathway in inhibitory but not excitatory neurons plays a key role in memory formation.

Molecular docking and dynamics simulation of farnesol as a potential anticancer agent targeting mTOR pathway

Farnesol is a natural acyclic sesquiterpene alcohol, found in various essential oils such as, lemon grass, citronella, tuberose, neroli, and musk. It has a molecular mass of 222.372 g/mol and chemical formula of C₁₅H₂₆O. The main objective of this study was to assess the effect of farnesol on mTOR and its two downstream effectors, p70S6K and eIF4E, which are implicated in the development of cancer, via molecular dynamic simulation, and docking analysis in an in silico study. A multilayer, primarily computer-based analysis was conducted to assess farnesol's anticancer potential, with a focus on primary cancer targets. From the calculations performed, farnesol showed a binding affinity of - 9.66 kcal/mol, followed by binding affinity of - 7.4 kcal/mol and - 7.8 kcal/mol for mTOR, p70S6K and eIF4E respectively. Rapamycin showed the binding affinity of - 10.45 kcal/mol for mTOR, for p70S6K and eIF4E the calculated binding affinity was - 10.65 kcal/mol and 8.16 kcal/mol respectively. The binding affinity of farnesol was comparable to the standard drug rapamycin indicating its potential as an mTOR inhibitor. Molecular dynamics simulations suggest that the ligands (farnesol and rapamycin) were well trapped within the active site of the protein over a time gap of 50 ns. It is clear that farnesol showed relatively stable MD simulation results, with minor fluctuations and maintains a consistent binding orientation, suggesting a strong and stable interaction with the target proteins when compared to simulation data of standard drug. This study explores the potential of farnesol as an anticancer agent through an in-silico approach, focusing on its interaction with mTOR and its downstream effectors. Inhibition of mTOR signaling pathway may be responsible for the anticancer effect of farnesol. As this pathway plays a crucial role in cell proliferation and survival, making it a significant target in cancer research.

TSC/mTORC1 mediates mTORC2/AKT1 signaling in c-MYC-induced murine hepatocarcinogenesis via centromere protein M

Activated mTORC2/AKT signaling plays a role in hepatocellular carcinoma (HCC). Research has shown that TSC/mTORC1 and FOXO1 are distinct downstream effectors of AKT signaling in liver regeneration and metabolism. However, the mechanisms by which these pathways mediate mTORC2/AKT activation in HCC are not yet fully understood. Amplification and activation of c-MYC are key molecular events in HCC. In this study, we explored the roles of tuberous sclerosis complex/mTORC1 (TSC/mTORC1) and FOXO1 as downstream effectors of mTORC2/AKT1 in c-MYC-induced hepatocarcinogenesis. Using various genetic approaches in mice, we found that manipulating the FOXO pathway had a minimal effect on c-MYC-induced HCC. In contrast, loss of mTORC2 inhibited c-MYC-induced HCC, an effect that was completely reversed by ablation of TSC2, which activated mTORC1. Additionally, we discovered that p70/RPS6 and 4EBP1/eIF4E acted downstream of mTORC1, regulating distinct molecular pathways. Notably, the 4EBP1/eIF4E cascade is crucial for cell proliferation and glycolysis in c-MYC-induced HCC. We also identified centromere protein M (CENPM) as a downstream target of the TSC2/mTORC1 pathway in c-MYC-driven hepatocarcinogenesis, and its ablation entirely inhibited c-MYC-dependent HCC formation. Our findings demonstrate that the TSC/mTORC1/CENPM pathway, rather than the FOXO cascade, is the primary signaling pathway regulating c-MYC-driven hepatocarcinogenesis. Targeting CENPM holds therapeutic potential for treating c-MYC-driven HCC.

Blockade of mTORC1 via Rapamycin Suppresses 27-Hydroxycholestrol-Induced Inflammatory Responses

Atherosclerosis is characterized by the deposition and accumulation of extracellular cholesterol and inflammatory cells in the arterial blood vessel walls, and 27-hydroxycholesterol (27OHChol) is the most abundant cholesterol metabolite. 27OHChol is an oxysterol that induces immune responses, including immune cell activation and chemokine secretion, although the underlying mechanisms are not fully understood. In this study, we investigated the roles of the mechanistic target of rapamycin (mTOR) in 27HChol-induced inflammation using rapamycin. Treating monocytic cells with rapamycin effectively reduced the expression of CCL2 and CD14, which was involved with the increased immune response by 27OHChol. Rapamycin also suppressed the phosphorylation of S6 and 4EBP1, which are downstream of mTORC1. Additionally, it also alleviates the increase in differentiation markers into macrophage. These results suggest that 27OHChol induces inflammation by activating the mTORC1 signaling pathway, and rapamycin may be useful for the treatment of atherosclerosis-related inflammation involving 27OHchol.

Targeting the RAS upstream and downstream signaling pathway for cancer treatment

Cancer often involves the overactivation of RAS/RAF/MEK/ERK (MAPK) and PI3K-Akt-mTOR pathways due to mutations in genes like RAS, RAF, PTEN, and PIK3CA. Various strategies are employed to address the overactivation of these pathways, among which targeted therapy emerges as a promising approach. Directly targeting specific proteins, leads to encouraging results in cancer treatment. For instance, RTK inhibitors such as imatinib and afatinib selectively target these receptors, hindering ligand binding and reducing signaling initiation. These inhibitors have shown potent efficacy against Non-Small Cell Lung Cancer. Other inhibitors, like lonafarnib targeting Farnesyltransferase and GGTI 2418 targeting geranylgeranyl Transferase, disrupt post-translational modifications of proteins. Additionally, inhibition of proteins like SOS, SH2 domain, and Ras demonstrate promising anti-tumor activity both in vivo and in vitro. Targeting downstream components with RAF inhibitors such as vemurafenib, dabrafenib, and sorafenib, along with MEK inhibitors like trametinib and binimetinib, has shown promising outcomes in treating cancers with BRAF-V600E mutations, including myeloma, colorectal, and thyroid cancers. Furthermore, inhibitors of PI3K (e.g., apitolisib, copanlisib), AKT (e.g., ipatasertib, perifosine), and mTOR (e.g., sirolimus, temsirolimus) exhibit promising efficacy against various cancers such as Invasive Breast Cancer, Lymphoma, Neoplasms, and Hematological malignancies. This review offers an overview of small molecule inhibitors targeting specific proteins within the RAS upstream and downstream signaling pathways in cancer.

Cutting edge of immune response and immunosuppressants in allogeneic and xenogeneic islet transplantation

As an effective treatment for diabetes, islet transplantation has garnered significant attention and research in recent years. However, immune rejection and the toxicity of immunosuppressive drugs remain critical factors influencing the success of islet transplantation. While immunosuppressants are essential in reducing immune rejection reactions and can significantly improve the survival rate of islet transplants, improper use of these drugs can markedly increase mortality rates following transplantation. Additionally, the current availability of islet organ donations fails to meet the demand for organ transplants, making xenotransplantation a crucial method for addressing organ shortages. This review will cover the following three aspects: 1) the immune responses occurring during allogeneic islet transplantation, including three stages: inflammation and IBMIR, allogeneic immune response, and autoimmune recurrence; 2) commonly used immunosuppressants in allogeneic islet transplantation, including calcineurin inhibitors (Cyclosporine A, Tacrolimus), mycophenolate mofetil, glucocorticoids, and Bortezomib; and 3) early and late immune responses in xenogeneic islet transplantation and the immune effects of triple therapy (ECDI-fixed donor spleen cells (ECDI-SP) + anti-CD20 + Sirolimus) on xenotransplantation.

mTORC1 mediates the expansion of hematopoietic stem and progenitor cells through ribosome biogenesis protein Urb2 in zebrafish

Mammalian target of rapamycin (mTOR) serves as the key sensor to control protein synthesis, cell growth, and survival. Despite mTOR is reported to regulate hematopoietic stem and progenitor cell (HSPC) engraftment and multiple-lineage hematopoiesis in mice, the roles of unique mTOR complexes (mTORCs) in early HSPC development and HSPC pool formation have not been adequately elucidated. Here, we uncover that mTORC1 is essential for early HSPC expansion in zebrafish. mTORC1 signaling was highly activated in definitive HSPCs during the emerging and expanding stages. Pharmacological or genetic inactivation of mTORC1 would cause defective HSPC expansion and migration due to disrupted cell proliferation. Interestingly, mTORC2 is dispensable for early HSPC development. Ribosome biogenesis protein Urb2 was downregulated upon mTORC1 inhibition, and urb2 overexpression partially rescued the hematopoietic defects in mTORC1-deficient embryos. These data demonstrate that mTORC1 signaling regulates early HSPC expansion through Urb2, and this work will deepen our understanding of mTOR in different physiological processes.

The Usnic Acid Analogue 4-FPBUA Enhances the Blood-Brain Barrier Function and Induces Autophagy in Alzheimer's Disease Mouse Models

Preclinical and clinical studies have indicated that compromised blood-brain barrier (BBB) function contributes to Alzheimer's disease (AD) pathology. BBB breakdown ranged from mild disruption of tight junctions (TJs) with increased BBB permeability to chronic integrity loss, affecting transport across the BBB, reducing brain perfusion, and triggering inflammatory responses. We recently developed a high-throughput screening (HTS) assay to identify hit compounds that enhance the function of a cell-based BBB model. The HTS screen identified (S,E)-2-acetyl-6-[3-(4'-fluorobiphenyl-4-yl)acryloyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo-[b,d]furan-1(9bH)-one (4-FPBUA), a semisynthetic analogue of naturally occurring usnic acid, which protected the in vitro model against Aβ toxicity. Usnic acid is a lichen-derived secondary metabolite with a unique dibenzofuran skeleton that is commonly found in lichenized fungi of the genera Usnea. In this study, we aimed to evaluate the effect of 4-FPBUA in vitro on the cell-based BBB model function and its in vivo ability to rectify BBB function and reduce brain Aβ in two AD mouse models, namely, 5xFAD and TgSwDI. Our findings demonstrated that 4-FPBUA enhanced cell-based BBB function, increased Aβ transport across the monolayer, and reversed BBB breakdown in vivo by enhancing autophagy as an mTOR inhibitor. Induced autophagy was associated with a significant reduction in Aβ accumulation and related pathologies and improved memory function. These results underscore the potential of 4-FPBUA as a candidate for further preclinical exploration to better understand its mechanisms of action and to optimize dosing strategies. Continued research may also elucidate additional pathways through which 4-FPBUA contributed to the amelioration of BBB dysfunction in AD. Collectively, our findings supported the development of 4-FPBUA as a therapeutic agent against AD.

Role of endothelial Raptor in abnormal arteriogenesis after lower limb ischaemia in type 2 diabetes

AIMS

Proper arteriogenesis after tissue ischaemia is necessary to rebuild stable blood circulation; nevertheless, this process is impaired in type 2 diabetes mellitus (T2DM). Raptor is a scaffold protein and a component of mammalian target of rapamycin complex 1 (mTORC1). However, the role of the endothelial Raptor in arteriogenesis under the conditions of T2DM remains unknown. This study investigated the role of endothelial Raptor in ischaemia-induced arteriogenesis during T2DM.

METHODS AND RESULTS

Although endothelial mTORC1 is hyperactive in T2DM, we observed a marked reduction in the expression of endothelial Raptor in two mouse models and in human vessels. Inducible endothelial-specific Raptor knockout severely exacerbated impaired hindlimb perfusion and arteriogenesis after hindlimb ischaemic injury in 12-week high-fat diet fed mice. Additionally, we found that Raptor deficiency dampened vascular endothelial growth factor receptor 2 (VEGFR2) signalling in endothelial cells (ECs) and inhibited VEGF-induced cell migration and tube formation in a PTP1B-dependent manner. Furthermore, mass spectrometry analysis indicated that Raptor interacts with neuropilin 1 (NRP1), the co-receptor of VEGFR2, and mediates VEGFR2 trafficking by facilitating the interaction between NRP1 and Synectin. Finally, we found that EC-specific overexpression of the Raptor mutant (loss of mTOR binding) reversed impaired hindlimb perfusion and arteriogenesis induced by endothelial Raptor knockout in high-fat diet fed mice.

CONCLUSION

Collectively, our study demonstrated the crucial role of endothelial Raptor in promoting ischaemia-induced arteriogenesis in T2DM by mediating VEGFR2 signalling. Thus, endothelial Raptor is a novel therapeutic target for promoting arteriogenesis and ameliorating perfusion in T2DM.

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.

Study on the regulatory mechanism of latent membrane protein 2A on GCNT3 expression in nasopharyngeal carcinoma

O-Glycan synthesis enzyme glucosaminyl (N-acetyl) transferase 3 (GCNT3) is closely related to the occurrence and development of various cancers. However, the regulatory mechanism and function of GCNT3 in nasopharyngeal carcinoma (NPC) are still poorly understood. This study aims to explore the regulatory mechanism of EBV-encoded latent membrane protein 2A (LMP2A) on GCNT3 and the biological role of GCNT3 in NPC. The results show that LMP2A can activate GCNT3 through the mTORC1 pathway, and there is a positive feedback between the mTORC1 and GCNT3. GCNT3 regulates EMT progression by forming a complex with ZEB1 to promote cell migration. GCNT3 can also promote cell proliferation. These findings indicate that targeting the LMP2A-mTORC1-GCNT3 axis may represent a novel therapeutic target in NPC.

MARCH1 negatively regulates TBK1-mTOR signaling pathway by ubiquitinating TBK1

BACKGROUND

TBK1 positively regulates the growth factor-mediated mTOR signaling pathway by phosphorylating mTOR. However, it remains unclear how the TBK1-mTOR signaling pathway is regulated. Considering that STING not only interacts with TBK1 but also with MARCH1, we speculated that MARCH1 might regulate the mTOR signaling pathway by targeting TBK1. The aim of this study was to determine whether MARCH1 regulates the mTOR signaling pathway by targeting TBK1.

METHODS

The co-immunoprecipitation (Co-IP) assay was used to verify the interaction between MARCH1 with STING or TBK1. The ubiquitination of STING or TBK1 was analyzed using denatured co-immunoprecipitation. The level of proteins detected in the co-immunoprecipitation or denatured co-immunoprecipitation samples were determined by Western blotting. Stable knocked-down cells were constructed by infecting lentivirus bearing the related shRNA sequences. Scratch wound healing and clonogenic cell survival assays were used to detect the migration and proliferation of breast cancer cells.

RESULTS

We showed that MARCH1 played an important role in growth factor-induced the TBK1- mTOR signaling pathway. MARCH1 overexpression attenuated the growth factor-induced activation of mTOR signaling pathway, whereas its deficiency resulted in the opposite effect. Mechanistically, MARCH1 interacted with and promoted the K63-linked ubiquitination of TBK1. This ubiquitination of TBK1 then attenuated its interaction with mTOR, thereby inhibiting the growth factor-induced mTOR signaling pathway. Importantly, faster proliferation induced by MARCH1 deficiency was weakened by mTOR, STING, or TBK1 inhibition.

CONCLUSION

MARCH1 suppressed growth factors mediated the mTOR signaling pathway by targeting the STING-TBK1-mTOR axis.

Importance of Energy, Dietary Protein Sources, and Amino Acid Composition in the Regulation of Metabolism: An Indissoluble Dynamic Combination for Life

PURPOSE

This paper aims to present a unique perspective that emphasizes the intricate interplay between energy, dietary proteins, and amino acid composition, underscoring their mutual dependence for health-related considerations. Energy and protein synthesis are fundamental to biological processes, crucial for the sustenance of life and the growth of organisms.

METHODS AND RESULTS

We explore the intricate relationship between energy metabolism, protein synthesis, regulatory mechanisms, protein sources, amino acid availability, and autophagy in order to elucidate how these elements collectively maintain cellular homeostasis. We underscore the vital role this dynamic interplay has in preserving cell life.

CONCLUSIONS

A deeper understanding of the link between energy and protein synthesis is essential to comprehend fundamental cellular processes. This insight could have a wide-ranging impact in several medical fields, such as nutrition, metabolism, and disease management.

Identifying autophagy-related mRNAs and potential ceRNA networks in meniscus degeneration based on RNA sequencing and experimental validation

Purpose

The intimate connection between long noncoding RNA (lncRNA) and autophagy has been established in cartilage degeneration. However, their roles in meniscal degeneration remain ambiguous. This study aimed to identify the key autophagy-related lncRNA and its associated regulatory network in meniscal degeneration in the context of osteoarthritis (OA).

Methods

RNA sequencing was performed to identify differentially expressed lncRNAs (DELs) and mRNAs (DEMs), which were then conducted to enrichment analyses using the DAVID database and Metascape. Autophagy-related DEMs were identified by combining DEMs with data from the Human Autophagy Database. Three databases were used to predict miRNA, and the DIANA LncBase Predicted database was utilized to predict miRNA-lncRNA interactions. Based on these predictions, comprehensive competitive endogenous RNA (ceRNA) network were constructed. The expression levels of the classical autophagy markers and autophagy-related ceRNA network were validated. Additionally, Gene Set Enrichment Analysis (GSEA) was performed using autophagy-related DEMs.

Results

310 DELs and 320 DEMs were identified, with five upregulated and one downregulated autophagy-related DEMs. Through reverse prediction of miRNA, paired miRNA-lncRNA interactions, and verification using RT-qPCR, two lncRNAs (PCAT19, CLIP1-AS1), two miRNA (has-miR-3680-3p and has-miR-4795-3p) and two mRNAs (BAG3 and HSP90AB1) were included in the constructed ceRNA regulatory networks. GSEA indicated that the increased expression of autophagy-related mRNAs inhibited glycosaminoglycan biosynthesis in the degenerative meniscus.

Conclusion

This study presented the first construction of regulatory ceRNA network involving autophagy-related lncRNA-miRNA-mRNA interactions in OA meniscus. These findings offered valuable insights into the mechanisms underlying meniscal degeneration and provided potential targets for therapeutic intervention.

Lomitapide repurposing for treatment of malignancies: A promising direction

The development of novel drugs from basic science to clinical practice requires several years, much effort, and cost. Drug repurposing can promote the utilization of clinical drugs in cancer therapy. Recent studies have shown the potential effects of lomitapide on treating malignancies, which is currently used for the treatment of familial hypercholesterolemia. We systematically review possible functions and mechanisms of lomitapide as an anti-tumor compound, regarding the aspects of apoptosis, autophagy, and metabolism of tumor cells, to support repurposing lomitapide for the clinical treatment of tumors.

Dissecting the multifaceted roles of autophagy in cancer initiation, growth, and metastasis: from molecular mechanisms to therapeutic applications

Autophagy is a cytoplasmic defense mechanism that cells use to break and reprocess their intracellular components. This utilization of autophagy is regarded as a savior in nutrient-deficient and other stressful conditions. Hence, autophagy keeps contact with and responds to miscellaneous cellular tensions and diverse pathways of signal transductions, such as growth signaling and cellular death. Importantly, autophagy is regarded as an effective tumor suppressor because regular autophagic breakdown is essential for cellular maintenance and minimizing cellular damage. However, paradoxically, autophagy has also been observed to promote the events of malignancies. This review discussed the dual role of autophagy in cancer, emphasizing its influence on tumor survival and progression. Possessing such a dual contribution to the malignant establishment, the prevention of autophagy can potentially advocate for the advancement of malignant transformation. In contrast, for the context of the instituted tumor, the agents of preventing autophagy potently inhibit the advancement of the tumor. Key regulators, including calpain 1, mTORC1, and AMPK, modulate autophagy in response to nutritional conditions and stress. Oncogenic mutations like RAS and B-RAF underscore autophagy's pivotal role in cancer development. The review also delves into autophagy's context-dependent roles in tumorigenesis, metastasis, and the tumor microenvironment (TME). It also discusses the therapeutic effectiveness of autophagy for several cancers. The recent implication of autophagy in the control of both innate and antibody-mediated immune systems made it a center of attention to evaluating its role concerning tumor antigens and treatments of cancer.

mTOR: Its Critical Role in Metabolic Diseases, Cancer, and the Aging Process

The mammalian target of rapamycin (mTOR) is a pivotal regulator, integrating diverse environmental signals to control fundamental cellular functions, such as protein synthesis, cell growth, survival, and apoptosis. Embedded in a complex network of signaling pathways, mTOR dysregulation is implicated in the onset and progression of a range of human diseases, including metabolic disorders such as diabetes and cardiovascular diseases, as well as various cancers. mTOR also has a notable role in aging. Given its extensive biological impact, mTOR signaling is a prime therapeutic target for addressing these complex conditions. The development of mTOR inhibitors has proven advantageous in numerous research domains. This review delves into the significance of mTOR signaling, highlighting the critical components of this intricate network that contribute to disease. Additionally, it addresses the latest findings on mTOR inhibitors and their clinical implications. The review also emphasizes the importance of developing more effective next-generation mTOR inhibitors with dual functions to efficiently target the mTOR pathways. A comprehensive understanding of mTOR signaling will enable the development of effective therapeutic strategies for managing diseases associated with mTOR dysregulation.

Non-coding RNA mediated regulation of PI3K/Akt pathway in hepatocellular carcinoma: Therapeutic perspectives

Hepatocellular carcinoma (HCC) is among the primary reasons for fatalities caused by cancer globally, highlighting the need for comprehensive knowledge of its molecular aetiology to develop successful treatment approaches. The PI3K/Akt system is essential in the course of HCC, rendering it an intriguing candidate for treatment. Non-coding RNAs (ncRNAs), such as long ncRNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), are important mediators of the PI3K/Akt network in HCC. The article delves into the complex regulatory functions of ncRNAs in influencing the PI3K/Akt system in HCC. The study explores how lncRNAs, miRNAs, and circRNAs impact the expression as well as the function of the PI3K/Akt network, either supporting or preventing HCC growth. Additionally, treatment strategies focusing on ncRNAs in HCC are examined, such as antisense oligonucleotide-based methods, RNA interference, and small molecule inhibitor technologies. Emphasizing the necessity of ensuring safety and effectiveness in clinical settings, limitations, and future approaches in using ncRNAs as therapies for HCC are underlined. The present study offers useful insights into the complex regulation system of ncRNAs and the PI3K/Akt cascade in HCC, suggesting possible opportunities for developing innovative treatment approaches to address this lethal tumor.

E4orf1: The triple agent of adenovirus - Unraveling its roles in oncogenesis, infectious obesity and immune responses in virus replication and vector therapy

Human Adenoviruses (HAdV) are nearly ubiquitous pathogens comprising numerous sub-types that infect various tissues and organs. Among many encoded proteins that facilitate viral replication and subversion of host cellular processes, the viral E4orf1 protein has emerged as an intriguing yet under-investigated player in the complex interplay between the virus and its host. E4orf1 has gained attention as a metabolism activator and oncogenic agent, while recent research is showing that E4orf1 may play a more important role in modulating cellular pathways such as PI3K-Akt-mTOR, Ras, the immune response and further HAdV replication stages than previously anticipated. In this review, we aim to explore the structure, molecular mechanisms, and biological functions of E4orf1, shedding light on its potentially multifaceted roles during HAdV infection, including metabolic diseases and oncogenesis. Furthermore, we discuss the role of functional E4orf1 in biotechnological applications such as Adenovirus (AdV) vaccine vectors and oncolytic AdV. By dissecting the intricate relationships between HAdV types and E4orf1 proteins, this review provides valuable insights into viral pathogenesis and points to promising areas of future research.

Rapamycin improves the survival of epilepsy model cells by blocking phosphorylation of mTOR base on computer simulations and cellular experiments

PURPOSE

Epilepsy is a chronic brain dysfunction characterized by recurrent epileptic seizures. Rapamycin is a naturally occurring macrolide from Streptomyces hygroscopicus, and rapamycin may provide a protective effect on the nervous system by affecting mTOR. Therefore, we investigated the pharmacologic mechanism of rapamycin treating epilepsy through bioinformatics analysis, cellular experiments and supercomputer simulation.

METHODS

Bioinformatics analysis was used to analyze targets of rapamycin treating epilepsy. We established epilepsy cell model by HT22 cells. RT-qPCR, WB and IF were used to verify the effects of rapamycin on mTOR at gene level and protein level. Computer simulations were used to model and evaluate the stability of rapamycin binding to mTOR protein.

RESULTS

Bioinformatics indicated mTOR played an essential role in signaling pathways of cell growth and cell metabolism. Cellular experiments showed that rapamycin could promote cell survival, and rapamycin did not have an effect on mRNA expression of mTOR. However, rapamycin was able to significantly inhibit the phosphorylation of mTOR at protein level. Computer simulations indicated that rapamycin was involved in the treatment of epilepsy through regulating phosphorylation of mTOR at protein level.

CONCLUSION

We found that rapamycin was capable of promoting the survival of epilepsy cells by inhibiting the phosphorylation of mTOR at protein level, and rapamycin did not have an effect on mRNA expression of mTOR. In addition to the traditional study that rapamycin affects mTORC1 complex by acting on FKBP12, this study found rapamycin could also directly block the phosphorylation of mTOR, therefore affecting the assembly of mTORC1 complex and mTOR signaling pathway.

Exercise, mTOR Activation, and Potential Impacts on the Liver in Rodents

The literature offers a consensus on the association between exercise training (ET) protocols based on the adequate parameters of intensity and frequency, and several adaptive alterations in the liver. Indeed, regular ET can reverse glucose and lipid metabolism disorders, especially from aerobic modalities, which can decrease intrahepatic fat formation. In terms of molecular mechanisms, the regulation of hepatic fat formation would be directly related to the modulation of the mechanistic target of rapamycin (mTOR), which would be stimulated by insulin signaling and Akt activation, from the following three different primary signaling pathways: (I) growth factor, (II) energy/ATP-sensitive, and (III) amino acid-sensitive signaling pathways, respectively. Hyperactivation of the Akt/mTORC1 pathway induces lipogenesis by regulating the action of sterol regulatory element binding protein-1 (SREBP-1). Exercise training interventions have been associated with multiple metabolic and tissue benefits. However, it is worth highlighting that the mTOR signaling in the liver in response to exercise interventions remains unclear. Hepatic adaptive alterations seem to be most outstanding when sustained by chronic interventions or high-intensity exercise protocols.

Should I shrink or should I grow: cell size changes in tissue morphogenesis

Cells change shape, move, divide, and die to sculpt tissues. Common to all these cell behaviours are cell size changes, which have recently emerged as key contributors to tissue morphogenesis. Cells can change their mass-the number of macromolecules they contain-or their volume-the space they encompass. Changes in cell mass and volume occur through different molecular mechanisms and at different timescales, slow for changes in mass and rapid for changes in volume. Therefore, changes in cell mass and cell volume, which are often linked, contribute to the development and shaping of tissues in different ways. Here, we review the molecular mechanisms by which cells can control and alter their size, and we discuss how changes in cell mass and volume contribute to tissue morphogenesis. The role that cell size control plays in developing embryos is only starting to be elucidated. Research on the signals that control cell size will illuminate our understanding of the cellular and molecular mechanisms that drive tissue morphogenesis.

The rapid proximity labeling system PhastID identifies ATP6AP1 as an unconventional GEF for Rheb

Rheb is a small G protein that functions as the direct activator of the mechanistic target of rapamycin complex 1 (mTORC1) to coordinate signaling cascades in response to nutrients and growth factors. Despite extensive studies, the guanine nucleotide exchange factor (GEF) that directly activates Rheb remains unclear, at least in part due to the dynamic and transient nature of protein-protein interactions (PPIs) that are the hallmarks of signal transduction. Here, we report the development of a rapid and robust proximity labeling system named Pyrococcus horikoshii biotin protein ligase (PhBPL)-assisted biotin identification (PhastID) and detail the insulin-stimulated changes in Rheb-proximity protein networks that were identified using PhastID. In particular, we found that the lysosomal V-ATPase subunit ATP6AP1 could dynamically interact with Rheb. ATP6AP1 could directly bind to Rheb through its last 12 amino acids and utilizes a tri-aspartate motif in its highly conserved C-tail to enhance Rheb GTP loading. In fact, targeting the ATP6AP1 C-tail could block Rheb activation and inhibit cancer cell proliferation and migration. Our findings highlight the versatility of PhastID in mapping transient PPIs in live cells, reveal ATP6AP1's role as an unconventional GEF for Rheb, and underscore the importance of ATP6AP1 in integrating mTORC1 activation signals through Rheb, filling in the missing link in Rheb/mTORC1 activation.

Review: The PI3K-AKT-mTOR signal transduction pathway in canine cancer

Tumors in dogs and humans share many similar molecular and genetic features, incentivizing a better understanding of canine neoplasms not only for the purpose of treating companion animals, but also to facilitate research of spontaneously developing tumors with similar biologic behavior and treatment approaches in an immunologically competent animal model. Multiple tumor types of both species have similar dysregulation of signal transduction through phosphatidylinositol 3-kinase (PI3K), protein kinase B (PKB; AKT), and mechanistic target of rapamycin (mTOR), collectively known as the PI3K-AKT-mTOR pathway. This review aims to delineate the pertinent aspects of the PI3K-AKT-mTOR signaling pathway in health and in tumor development. It will then present a synopsis of current understanding of PI3K-AKT-mTOR signaling in important canine cancers and advancements in targeted inhibitors of this pathway.

Galectin-8 modulates human osteoclast activity partly through isoform-specific interactions

In overactive human osteoclasts, we previously identified an alternative splicing event in LGALS8, encoding galectin-8, resulting in decreased expression of the long isoform. Galectin-8, which modulates cell-matrix interactions and functions intracellularly as a danger recognition receptor, has never been associated with osteoclast biology. In human osteoclasts, inhibition of galectin-8 expression revealed its roles in bone resorption, osteoclast nuclearity, and mTORC1 signaling regulation. Galectin-8 isoform-specific inhibition asserted a predominant role for the short isoform in bone resorption. Moreover, a liquid chromatography with tandem mass spectrometry (LC-MS/MS) proteomic analysis of galectin-8 isoforms performed in HEK293T cells identified 22 proteins shared by both isoforms. Meanwhile, nine interacting partners were specific for the short isoform, and none were unique to the long isoform. Interactors specific for the galectin-8 short isoform included cell adhesion proteins and lysosomal proteins. We confirmed the interactions of galectin-8 with CLCN3, CLCN7, LAMP1, and LAMP2, all known to localize to secretory vesicles, in human osteoclasts. Altogether, our study reveals direct roles of galectin-8 in osteoclast activity, mostly attributable to the short isoform.

Inhibition of Prostate Cancer Cell Survival and Proliferation by Carnosic Acid Is Associated with Inhibition of Akt and Activation of AMPK Signaling

Prostate cancer, accounting for 375,304 deaths in 2020, is the second most prevalent cancer in men worldwide. While many treatments exist for prostate cancer, novel therapeutic agents with higher efficacy are needed to target aggressive and hormone-resistant forms of prostate cancer, while sparing healthy cells. Plant-derived chemotherapy drugs such as docetaxel and paclitaxel have been established to treat cancers including prostate cancer. Carnosic acid (CA), a phenolic diterpene found in the herb rosemary (Rosmarinus officinalis) has been shown to have anticancer properties but its effects in prostate cancer and its mechanisms of action have not been examined. CA dose-dependently inhibited PC-3 and LNCaP prostate cancer cell survival and proliferation (IC50: 64, 21 µM, respectively). Furthermore, CA decreased phosphorylation/activation of Akt, mTOR, and p70 S6K. A notable increase in phosphorylation/activation of AMP-activated kinase (AMPK), acetyl-CoA carboxylase (ACC) and its upstream regulator sestrin-2 was seen with CA treatment. Our data indicate that CA inhibits AKT-mTORC1-p70S6K and activates Sestrin-2-AMPK signaling leading to a decrease in survival and proliferation. The use of inhibitors and small RNA interference (siRNA) approaches should be employed, in future studies, to elucidate the mechanisms involved in carnosic acid's inhibitory effects of prostate cancer.

The human adenovirus PI3K-Akt activator E4orf1 is targeted by the tumor suppressor p53

Human adenoviruses (HAdV) are classified as DNA tumor viruses due to their potential to mediate oncogenic transformation in non-permissive mammalian cells and certain human stem cells. To achieve transformation, the viral early proteins of the E1 and E4 regions must block apoptosis and activate proliferation: the former predominantly through modulating the cellular tumor suppressor p53 and the latter by activating cellular pro-survival and pro-metabolism protein cascades, such as the phosphoinositide 3-kinase (PI3K-Akt) pathway, which is activated by HAdV E4orf1. Focusing on HAdV-C5, we show that E4orf1 is necessary and sufficient to stimulate Akt activation through phosphorylation in H1299 cells, which is not only hindered but repressed during HAdV-C5 infection with a loss of E4orf1 function in p53-positive A549 cells. Contrary to other research, E4orf1 localized not only in the common, cytoplasmic PI3K-Akt-containing compartment, but also in distinct nuclear aggregates. We identified a novel inhibitory mechanism, where p53 selectively targeted E4orf1 to destabilize it, also stalling E4orf1-dependent Akt phosphorylation. Co-IP and immunofluorescence studies showed that p53 and E4orf1 interact, and since p53 is bound by the HAdV-C5 E3 ubiquitin ligase complex, we also identified E4orf1 as a novel factor interacting with E1B-55K and E4orf6 during infection; overexpression of E4orf1 led to less-efficient E3 ubiquitin ligase-mediated proteasomal degradation of p53. We hypothesize that p53 specifically subverts the pro-survival function of E4orf1-mediated PI3K-Akt activation to protect the cell from metabolic hyper-activation or even transformation.IMPORTANCEHuman adenoviruses (HAdV) are nearly ubiquitous pathogens comprising numerous subtypes that infect various tissues and organs. Among many encoded proteins that facilitate viral replication and subversion of host cellular processes, the viral E4orf1 protein has emerged as an intriguing yet under-investigated player in the complex interplay between the virus and its host. Nonetheless, E4orf1 has gained attention as a metabolism activator and oncogenic agent, while recent research is showing that E4orf1 may play a more important role in modulating the cellular pathways such as phosphoinositide 3-kinase-Akt-mTOR. Our study reveals a novel and general impact of E4orf1 on host mechanisms, providing a novel basis for innovative antiviral strategies in future therapeutic settings. Ongoing investigations of the cellular pathways modulated by HAdV are of great interest, particularly since adenovirus-based vectors actually serve as vaccine or gene vectors. HAdV constitute an ideal model system to analyze the underlying molecular principles of virus-induced tumorigenesis.

FLRT2 prevents endothelial cell senescence and vascular aging by regulating the ITGB4/mTORC2/p53 signaling pathway

The roles of fibronectin leucine-rich transmembrane protein 2 (FLRT2) in physiological and pathological processes are not well known. Here, we identify a potentially novel function of FLRT2 in preventing endothelial cell senescence and vascular aging. We found that FLRT2 expression was lower in cultured senescent endothelial cells as well as in aged rat and human vascular tissues. FLRT2 mediated endothelial cell senescence via the mTOR complex 2, AKT, and p53 signaling pathway in human endothelial cells. We uncovered that FLRT2 directly associated with integrin subunit beta 4 (ITGB4) and thereby promoted ITGB4 phosphorylation, while inhibition of ITGB4 substantially mitigated the induction of senescence triggered by FLRT2 depletion. Importantly, FLRT2 silencing in mice promoted vascular aging, and overexpression of FLRT2 rescued a premature vascular aging phenotype. Therefore, we propose that FLRT2 could be targeted therapeutically to prevent senescence-associated vascular aging.

Metformin: A Dual-Role Player in Cancer Treatment and Prevention

Cancer continues to pose a significant global health challenge, as evidenced by the increasing incidence rates and high mortality rates, despite the advancements made in chemotherapy. The emergence of chemoresistance further complicates the effectiveness of treatment. However, there is growing interest in the potential of metformin, a commonly prescribed drug for type 2 diabetes mellitus (T2DM), as an adjuvant chemotherapy agent in cancer treatment. Although the precise mechanism of action of metformin in cancer therapy is not fully understood, it has been found to have pleiotropic effects, including the modulation of metabolic pathways, reduction in inflammation, and the regulation of cellular proliferation. This comprehensive review examines the anticancer properties of metformin, drawing insights from various studies conducted in vitro and in vivo, as well as from clinical trials and observational research. This review discusses the mechanisms of action involving both insulin-dependent and independent pathways, shedding light on the potential of metformin as a therapeutic agent for different types of cancer. Despite promising findings, there are challenges that need to be addressed, such as conflicting outcomes in clinical trials, considerations regarding dosing, and the development of resistance. These challenges highlight the importance of further research to fully harness the therapeutic potential of metformin in cancer treatment. The aims of this review are to provide a contemporary understanding of the role of metformin in cancer therapy and identify areas for future exploration in the pursuit of effective anticancer strategies.

mTORC1 in energy expenditure: consequences for obesity

In eukaryotic cells, the mammalian target of rapamycin complex 1 (sometimes referred to as the mechanistic target of rapamycin complex 1; mTORC1) orchestrates cellular metabolism in response to environmental energy availability. As a result, at the organismal level, mTORC1 signalling regulates the intake, storage and use of energy by acting as a hub for the actions of nutrients and hormones, such as leptin and insulin, in different cell types. It is therefore unsurprising that deregulated mTORC1 signalling is associated with obesity. Strategies that increase energy expenditure offer therapeutic promise for the treatment of obesity. Here we review current evidence illustrating the critical role of mTORC1 signalling in the regulation of energy expenditure and adaptive thermogenesis through its various effects in neuronal circuits, adipose tissue and skeletal muscle. Understanding how mTORC1 signalling in one organ and cell type affects responses in other organs and cell types could be key to developing better, safer treatments targeting this pathway in obesity.

The role of TSC1 and TSC2 proteins in neuronal axons

Tuberous Sclerosis Complex 1 and 2 proteins, TSC1 and TSC2 respectively, participate in a multiprotein complex with a crucial role for the proper development and function of the nervous system. This complex primarily acts as an inhibitor of the mechanistic target of rapamycin (mTOR) kinase, and mutations in either TSC1 or TSC2 cause a neurodevelopmental disorder called Tuberous Sclerosis Complex (TSC). Neurological manifestations of TSC include brain lesions, epilepsy, autism, and intellectual disability. On the cellular level, the TSC/mTOR signaling axis regulates multiple anabolic and catabolic processes, but it is not clear how these processes contribute to specific neurologic phenotypes. Hence, several studies have aimed to elucidate the role of this signaling pathway in neurons. Of particular interest are axons, as axonal defects are associated with severe neurocognitive impairments. Here, we review findings regarding the role of the TSC1/2 protein complex in axons. Specifically, we will discuss how TSC1/2 canonical and non-canonical functions contribute to the formation and integrity of axonal structure and function.