Insulin and amino-acid regulation of mTOR signaling and kinase activity through the Rheb GTPase

Unraveling the Role of Ras Homolog Enriched in Brain (Rheb1 and Rheb2): Bridging Neuronal Dynamics and Cancer Pathogenesis through Mechanistic Target of Rapamycin Signaling

Ras homolog enriched in brain (Rheb1 and Rheb2), small GTPases, play a crucial role in regulating neuronal activity and have gained attention for their implications in cancer development, particularly in breast cancer. This study delves into the intricate connection between the multifaceted functions of Rheb1 in neurons and cancer, with a specific focus on the mTOR pathway. It aims to elucidate Rheb1's involvement in pivotal cellular processes such as proliferation, apoptosis resistance, migration, invasion, metastasis, and inflammatory responses while acknowledging that Rheb2 has not been extensively studied. Despite the recognized associations, a comprehensive understanding of the intricate interplay between Rheb1 and Rheb2 and their roles in both nerve and cancer remains elusive. This review consolidates current knowledge regarding the impact of Rheb1 on cancer hallmarks and explores the potential of Rheb1 as a therapeutic target in cancer treatment. It emphasizes the necessity for a deeper comprehension of the molecular mechanisms underlying Rheb1-mediated oncogenic processes, underscoring the existing gaps in our understanding. Additionally, the review highlights the exploration of Rheb1 inhibitors as a promising avenue for cancer therapy. By shedding light on the complicated roles between Rheb1/Rheb2 and cancer, this study provides valuable insights to the scientific community. These insights are instrumental in guiding the identification of novel targets and advancing the development of effective therapeutic strategies for treating cancer.

Identification and characterization of TOR in Macrobrachium rosenbergii and its role in muscle protein and lipid production

The recent scarcity of fishmeal and other resources means that studies on the intrinsic mechanisms of nutrients in the growth and development of aquatic animals at the molecular level have received widespread attention. The target of rapamycin (TOR) pathway has been reported to receive signals from nutrients and environmental stresses, and regulates cellular anabolism and catabolism to achieve precise regulation of cell growth and physiological activities. In this study, we cloned and characterized the full-length cDNA sequence of the TOR gene of Macrobrachium rosenbergii (MrTOR). MrTOR was expressed in all tissues, with higher expression in heart and muscle tissues. In situ hybridization also indicated that MrTOR was expressed in muscle, mainly around the nucleus. RNA interference decreased the expression levels of MrTOR and downstream protein synthesis-related genes (S6K, eIF4E, and eIF4B) (P < 0.05) and the expression and enzyme activity of the lipid synthesis-related enzyme, fatty acid synthase (FAS), and increased enzyme activity of the lipolysis-related enzyme, lipase (LPS). In addition, amino acid injection significantly increased the transcript levels of MrTOR and downstream related genes (S6K, eIF4E, eIF4B, and FAS), as well as triglyceride and total cholesterol tissue levels and FAS activity. Starvation significantly increased transcript levels and enzyme activities of adenylate-activated protein kinase and LPS and decreased transcript levels and enzyme activities of FAS, as well as transcript levels of MrTOR and its downstream genes (P < 0.05), whereas amino acid injection alleviated the starvation-induced decreases in transcript levels of these genes. These results suggested that arginine and leucine activated the TOR signaling pathway, promoted protein and lipid syntheses, and alleviated the pathway changes induced by starvation.

Regeneration of Pancreatic Beta Cells by Modulation of Molecular Targets Using Plant-Derived Compounds: Pharmacological Mechanisms and Clinical Potential

Type 2 diabetes (T2D) is characterized by pancreatic beta-cell dysfunction, increased cell death and loss of beta-cell mass despite chronic treatment. Consequently, there has been growing interest in developing beta cell-centered therapies. Beta-cell regeneration is mediated by augmented beta-cell proliferation, transdifferentiation of other islet cell types to functional beta-like cells or the reprograming of beta-cell progenitors into fully differentiated beta cells. This mediation is orchestrated by beta-cell differentiation transcription factors and the regulation of the cell cycle machinery. This review investigates the beta-cell regenerative potential of antidiabetic plant extracts and phytochemicals. Various preclinical studies, including in vitro, in vivo and ex vivo studies, are highlighted. Further, the potential regenerative mechanisms and the intra and extracellular mediators that are of significance are discussed. Also, the potential of phytochemicals to translate into regenerative therapies for T2D patients is highlighted, and some suggestions regarding future perspectives are made.

Cell cycle control by the insulin-like growth factor signal: at the crossroad between cell growth and mitotic regulation

In proliferating cells and tissues a number of checkpoints (G1/S and G2/M) preceding cell division (M-phase) require the signal provided by growth factors present in serum. IGFs (I and II) have been demonstrated to constitute key intrinsic components of the peptidic active fraction of mammalian serum. In vivo genetic ablation studies have shown that the cellular signal triggered by the IGFs through their cellular receptors represents a non-replaceable requirement for cell growth and cell cycle progression. Retroactive and current evaluation of published literature sheds light on the intracellular circuitry activated by these factors providing us with a better picture of the pleiotropic mechanistic actions by which IGFs regulate both cell size and mitogenesis under developmental growth as well as in malignant proliferation. The present work aims to summarize the cumulative knowledge learned from the IGF ligands/receptors and their intracellular signaling transducers towards control of cell size and cell-cycle with particular focus to their actionable circuits in human cancer. Furthermore, we bring novel perspectives on key functional discriminants of the IGF growth-mitogenic pathway allowing re-evaluation on some of its signal components based upon established evidences.

Human T2D-Associated Gene IMP2/IGF2BP2 Promotes the Commitment of Mesenchymal Stem Cells Into Adipogenic Lineage

Excessive adiposity is the main cause of obesity and type two diabetes (T2D). Variants in human IMP2/IGF2BP2 gene are associated with increased risk of T2D. However, little is known about its role in adipogenesis and in insulin resistance. Here, we investigate the function of IMP2 during adipocyte development. Mice with Imp2 deletion in mesenchymal stem cells (MSC) are resistant to diet-induced obesity without glucose and insulin tolerance affected. Imp2 is essential for the early commitment of adipocyte-derived stem cells (ADSC) into preadipocytes, but the deletion of Imp2 in MSC is not required for the proliferation and terminal differentiation of committed preadipocytes. Mechanistically, Imp2 binds Wnt receptor Fzd8 mRNA and promotes its degradation by recruiting CCR4-NOT deadenylase complex in an mTOR-dependent manner. Our data demonstrate that Imp2 is required for maintaining white adipose tissue homeostasis through controlling mRNA stability in ADSC. However, the contribution of IMP2 to insulin resistance, a main risk of T2D, is not evident.

Targeting mTORC1 Activity to Improve Efficacy of Radioligand Therapy in Cancer

Radioligand therapy (RLT) represents an effective strategy to treat malignancy by cancer-selective delivery of radioactivity following systemic application. Despite recent therapeutic successes, cancer radioresistance and insufficient delivery of the radioactive ligands, as well as cytotoxicity to healthy organs, significantly impairs clinical efficacy. To improve disease management while minimizing toxicity, in recent years, the combination of RLT with molecular targeted therapies against cancer signaling networks showed encouraging outcomes. Characterization of the key deregulated oncogenic signaling pathways revealed their convergence to activate the mammalian target of rapamycin (mTOR), in which signaling plays an essential role in the regulation of cancer growth and survival. Therapeutic interference with hyperactivated mTOR pathways was extensively studied and led to the development of mTOR inhibitors for clinical applications. In this review, we outline the regulation and oncogenic role of mTOR signaling, as well as recapitulate and discuss mTOR complex 1 (mTORC1) inhibition to improve the efficacy of RLT in cancer.

Bovine lactoferricin on non-specific immunity of giant freshwater prawns, Macrobrachium rosenbergii

This study aimed to investigate the effects of dietary Bovine lactoferricin (LFcinB) on the growth performance and non-specific immunity in Macrobrachium rosenbergii. Five experimental diets were 1.0‰ Bovine lactoferricin (LCB1); 1.5‰ Bovine lactoferricin (LCB1.5); 2.0‰ Bovine lactoferricin (LCB2); 2.5‰ Bovine lactoferricin (LCB2.5); the control group, basal diet without Bovine lactoferricin. A total of 600 prawns were randomly assigned to 5 groups in triplicate in 15 tanks for an 8-week feeding trial. The results showed the final weight, weight gain rate, specific growth rate and survival rate of prawns in the treatment groups were significantly improved versus the control (P < 0.05). The feed conversion ratio was reduced significantly in treatment groups compared to the control (P < 0.05). Compared with the control, alkaline phosphatase (AKP), acid phosphatase (ACP), lysozyme (LZM), catalase (CAT), superoxide dismutase (SOD) activities in the hepatopancreas of the treatment groups were significantly enhanced, and malondialdehyde (MDA) content was reduced significantly (P < 0.05). Compared with the control, the relative expression levels of AKP, ACP, LZM, CAT, SOD, Hsp70, peroxiredoxin-5, Toll, dorsal and relish genes were significantly higher among treatment groups, except for the AKP gene in the LCB1 group and the Hsp70 gene in the LCB1.5 group (P < 0.05). Compared with the control, the relative expression levels of TOR, 4E-BP, eIF4E1α and eIF4E2 genes were significantly enhanced in the LCB1.5 group (P < 0.05). When resistance against Vibrio parahaemolyticus in prawn is considered, higher doses of Bovine lactoferricin show better antibacterial ability. The present study indicated that dietary Bovine lactoferricin could significantly improve the growth performance and improve the antioxidative status of M. rosenbergii. The suitable addition level is 1.5 g/kg. LFcinB has great potential as a new feed additive without the threat of drug resistance.

Drosophila as a Model Organism to Study Basic Mechanisms of Longevity

The spatio-temporal regulation of gene expression determines the fate and function of various cells and tissues and, as a consequence, the correct development and functioning of complex organisms. Certain mechanisms of gene activity regulation provide adequate cell responses to changes in environmental factors. Aside from gene expression disorders that lead to various pathologies, alterations of expression of particular genes were shown to significantly decrease or increase the lifespan in a wide range of organisms from yeast to human. Drosophila fruit fly is an ideal model system to explore mechanisms of longevity and aging due to low cost, easy handling and maintenance, large number of progeny per adult, short life cycle and lifespan, relatively low number of paralogous genes, high evolutionary conservation of epigenetic mechanisms and signalling pathways, and availability of a wide range of tools to modulate gene expression in vivo. Here, we focus on the organization of the evolutionarily conserved signaling pathways whose components significantly influence the aging process and on the interconnections of these pathways with gene expression regulation.

Combined targeting of pathways regulating synaptic formation and autophagy attenuates Alzheimer’s disease pathology in mice

All drug trials completed to date have fallen short of meeting the clinical endpoint of significantly slowing cognitive decline in Alzheimer’s disease (AD) patients. In this study, we repurposed two FDA-approved drugs, Fasudil and Lonafarnib, targeting synaptic formation (i.e., Wnt signaling) and cellular clearance (i.e., autophagic) pathways respectively, to test their therapeutic potential for attenuating AD-related pathology. We characterized our 3xTg AD mouse colony to select timepoints for separate and combinatorial treatment of both drugs while collecting cerebrospinal fluid (CSF) using an optimized microdialysis method. We found that treatment with Fasudil reduced Aβ at early and later stages of AD, whereas administration of Lonafarnib had no effect on Aβ, but did reduce tau, at early stages of the disease. Induction of autophagy led to increased size of amyloid plaques when administered at late phases of the disease. We show that combinatorial treatment with both drugs was effective at reducing intraneuronal Aβ and led to improved cognitive performance in mice. These findings lend support to regulating Wnt and autophagic pathways in order to attenuate AD-related pathology.

Differential effect of two dietary protein sources on time course response of muscle anabolic signaling pathways in normal and insulin dysregulated horses

The objective of the study was to characterize the temporal changes of phosphorylation patterns of mTOR signaling proteins in response to two dietary protein sources in insulin dysregulated (ID, n = 8) and non-ID (n = 8) horses. Horses were individually housed and fed timothy grass hay and 2 daily concentrate meals so that protein was the first limiting nutrient and the total diet provided 120% of daily DE requirements for maintenance. On sample days, horses randomly received 0.25 g CP/kg BW of a pelleted alfalfa (AP) or commercial protein supplement (PS). Blood samples were collected before and 30, 60, 90, 120, 150, 180, 210, 240, 300, 360, 420, and 480 min post feeding and analyzed for plasma glucose, insulin and amino acid (AA) concentrations. Gluteus Medius muscle samples were obtained before and 90, 180, and 300 min after feeding and analyzed for relative abundance of phosphorylated mTOR pathway components using western immunoblot analysis. There was no effect of protein source on postprandial glucose and insulin responses (P ≥ 0.14) but consumption of PS elicited a 2 times larger AUC for essential AA (EAA), greater peak concentrations of EAA and a shorter time to reach peak EAA concentrations compared to AP. Abundance of phosphorylated mTOR (P = 0.08) and rpS6 (P = 0.10) tended to be ~1.5-fold greater after consumption of PS at 90 min compared to AP. Dephosphorylation patterns differed between protein sources and was slower for AP compared to PS. ID horses had a 2 times greater (P = 0.009) AUC and 3 times higher postprandial peak concentrations (P &lt; 0.0001) for insulin compared to non-ID horses after consumption of both treatment pellets, but EAA responses were similar between groups (P = 0.53). Insulin status did not affect rpS6 or mTOR phosphorylation after consumption of either protein source (P ≥ 0.35), but phosphorylated rpS6 abundance was twice as high in ID compared to non-ID horses (P = 0.007). These results suggest that the consumption of higher quality protein sources may result in greater postprandial activation of the mTOR pathway compared to equal amounts of a forage-based protein source. Moreover, ID does not impair postprandial activation of mTOR and rpS6 proteins in horses following a protein-rich meal.

Targeting mTORC2/HDAC3 Inhibits Stemness of Liver Cancer Cells Against Glutamine Starvation

Cancer cells are addicted to glutamine. However, cancer cells often suffer from glutamine starvation, which largely results from the fast growth of cancer cells and the insufficient vascularization in the interior of cancer tissues. Herein, based on clinical samples, patient-derived cells (PDCs), and cell lines, it is found that liver cancer cells display stem-like characteristics upon glutamine shortage due to maintaining the stemness of tumor initiating cells (TICs) and even promoting transformation of non-TICs into stem-like cells by glutamine starvation. Increased expression of glutamine synthetase (GS) is essential for maintaining and promoting stem-like characteristics of liver cancer cells during glutamine starvation. Mechanistically, glutamine starvation activates Rictor/mTORC2 to induce HDAC3-mediated deacetylation and stabilization of GS. Rictor is significantly correlated with the expression of GS and stem marker OCT4 at tumor site, and closely correlates with poor prognosis of hepatocellular carcinomas. Inhibiting components of mTORC2-HDAC3-GS axis decrease TICs and promote xenografts regression upon glutamine-starvation therapy. Collectively, the data provides novel insights into the role of Rictor/mTORC2-HDAC3 in reprogramming glutamine metabolism to sustain stemness of cancer cells. Targeting Rictor/HDAC3 may enhance the efficacy of glutamine-starvation therapy and limit the rapid growth and malignant progression of tumors.

Targeting the PI3K/AKT/mTOR pathway in epithelial ovarian cancer, therapeutic treatment options for platinum-resistant ovarian cancer

The survival rates for women with ovarian cancer have shown scant improvement in recent years, with a 5-year survival rate of less than 40% for women diagnosed with advanced ovarian cancer. High-grade serous ovarian cancer (HGSOC) is the most lethal subtype where the majority of women develop recurrent disease and chemotherapy resistance, despite over 70%-80% of patients initially responding to platinum-based chemotherapy. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway regulates many vital processes such as cell growth, survival and metabolism. However, this pathway is frequently dysregulated in cancers including different subtypes of ovarian cancer, through amplification or somatic mutations of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), amplification of AKT isoforms, or deletion or inactivation of PTEN. Further evidence indicates a role for the PI3K/AKT/mTOR pathway in the development of chemotherapy resistance in ovarian cancer. Thus, targeting key nodes of the PI3K/AKT/mTOR pathway is a potential therapeutic prospect. In this review, we outline dysregulation of PI3K signaling in ovarian cancer, with a particular emphasis on HGSOC and platinum-resistant disease. We review pre-clinical evidence for inhibitors of the main components of the PI3K pathway and highlight past, current and upcoming trials in ovarian cancers for different inhibitors of the pathway. Whilst no inhibitors of the PI3K/AKT/mTOR pathway have thus far advanced to the clinic for the treatment of ovarian cancer, several promising compounds which have the potential to restore platinum sensitivity and improve clinical outcomes for patients are under evaluation and in various phases of clinical trials.

The TORC1 phosphoproteome in C. elegans reveals roles in transcription and autophagy

The protein kinase complex target of rapamycin complex 1 (TORC1) is a critical mediator of nutrient sensing that has been widely studied in cultured cells and yeast, yet our understanding of the regulatory activities of TORC1 in the context of a whole, multi-cellular organism is still very limited. Using Caenorhabditis elegans, we analyzed the DAF-15/Raptor-dependent phosphoproteome by quantitative mass spectrometry and characterized direct kinase targets by in vitro kinase assays. Here, we show new targets of TORC1 that indicate previously unknown regulation of transcription and autophagy. Our results further show that DAF-15/Raptor is differentially expressed during postembryonic development, suggesting a dynamic role for TORC1 signaling throughout the life span. This study provides a comprehensive view of the TORC1 phosphoproteome, reveals more than 100 DAF-15/Raptor-dependent phosphosites that reflect the complex function of TORC1 in a whole, multi-cellular organism, and serves as a rich resource to the field.

•

Detailed, unbiased analysis of the Caenorhabditis elegans TORC1 phosphoproteome

•

Characterization of DAF-15 expression and localization

•

TORC1 direct targets with roles in transcription machinery and autophagy

•

Unique technical approach and datasets provide rich resource to the field

Downregulation of NEDD4L by EGFR signaling promotes the development of lung adenocarcinoma

Cumulative evidence indicates that the abnormal regulation of the NEDD4 family of E3-ubiquitin ligases participates in the tumorigenesis and development of cancer. However, their role in lung adenocarcinoma (LUAD) remains unclear. This study comprehensively analyzed the NEDD4 family in LUAD data sets from public databases and found only NEDD4L was associated with the overall survival of LUAD patients. Gene set enrichment analysis (GSEA) indicated that NEDD4L might be involved in the regulation of mTORC1 pathway. Both cytological and clinical assays showed that NEDD4L inhibited the activity of the mTOR signaling pathway. In vivo and in vitro experiments showed that NEDD4L could significantly inhibit the proliferation of LUAD cells. In addition, this study also found that the expression of NEDD4L was regulated by EGFR signaling. These findings firstly revealed that NEDD4L mediates an interplay between EGFR and mTOR pathways in LUAD, and suggest that NEDD4L held great potential as a novel biomarker and therapeutic target for LUAD.

Regulation of mTORC1 by amino acids in mammalian cells: A general picture of recent advances

The mechanistic target of rapamycin complex 1 (mTORC1) integrates various types of signal inputs, such as energy, growth factors, and amino acids to regulate cell growth and proliferation mainly through the 2 direct downstream targets, eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) and ribosomal protein S6 kinase 1 (S6K1). Most of the signal arms upstream of mTORC1 including energy status, stress signals, and growth factors converge on the tuberous sclerosis complex (TSC) - Ras homologue enriched in brain (Rheb) axis. Amino acids, however, are distinct from other signals and modulate mTORC1 using a unique pathway. In recent years, the transmission mechanism of amino acid signals upstream of mTORC1 has been gradually elucidated, and some sensors or signal transmission pathways for individual amino acids have also been discovered. With the help of these findings, we propose a general picture of recent advances, which demonstrates that various amino acids from lysosomes, cytoplasm, and Golgi are sensed by their respective sensors. These signals converge on mTORC1 and form a huge and complicated signal network with multiple synergies, antagonisms, and feedback mechanisms.

Pyrimidine Biosynthetic Enzyme CAD: Its Function, Regulation, and Diagnostic Potential

CAD (Carbamoyl-phosphate synthetase 2, Aspartate transcarbamoylase, and Dihydroorotase) is a multifunctional protein that participates in the initial three speed-limiting steps of pyrimidine nucleotide synthesis. Over the past two decades, extensive investigations have been conducted to unmask CAD as a central player for the synthesis of nucleic acids, active intermediates, and cell membranes. Meanwhile, the important role of CAD in various physiopathological processes has also been emphasized. Deregulation of CAD-related pathways or CAD mutations cause cancer, neurological disorders, and inherited metabolic diseases. Here, we review the structure, function, and regulation of CAD in mammalian physiology as well as human diseases, and provide insights into the potential to target CAD in future clinical applications.

The effects of glucagon and the target of rapamycin (TOR) on skeletal muscle protein synthesis and age-dependent sarcopenia in humans

BACKGROUND AND AIMS

Human target of rapamycin (TOR) is a kinase that stimulates protein synthesis in the skeletal muscle in response to amino acids and physical activity.

METHODS

A comprehensive literature search was conducted on the PubMed database from its inception up to May 2021 to retrieve information on the effects of TOR and glucagon on muscle function. Articles written in English regarding human subjects were included.

RESULTS

l-leucine activates TOR to initiate protein synthesis in the skeletal muscle. Glucagon has a crucial role suppressing skeletal muscle protein synthesis by increasing l-leucine oxidation and the irreversible loss of this amino acid. Glucagon-induced l-leucine oxidation suppresses TOR and attenuates the ability of skeletal muscle to synthesize proteins. Conditions associated with increased glucagon secretion typically feature reduced ability to synthesize proteins in the skeletal muscle that may evolve into sarcopenia. Animal protein ingestion, unlike vegetable protein, stimulates glucagon secretion. High intake of animal protein increases l-leucine oxidation and promotes the use of amino acids as fuel. Sarcopenia and arterial stiffness characteristically occur together in conditions featuring insulin resistance, such as aging. Insulin resistance mediates the relationship between aging and sarcopenia and arterial stiffness. The loss of skeletal muscle fibers that characterizes sarcopenia is followed by collagen and lipid accumulation. Likewise, insulin resistance is associated with arterial stiffness and intima-media thickening due to adaptive accretion of collagen and lipids in the arterial wall.

CONCLUSIONS

Human TOR participates in the pathogenesis of sarcopenia and arterial stiffness, although its effects remain to be fully elucidated.

Therapeutic Potential of AAV1-Rheb(S16H) Transduction against Neurodegenerative Diseases

Neurotrophic factors (NTFs) are essential for cell growth, survival, synaptic plasticity, and maintenance of specific neuronal population in the central nervous system. Multiple studies have demonstrated that alterations in the levels and activities of NTFs are related to the pathology and symptoms of neurodegenerative disorders, such as Parkinson’s disease (PD), Alzheimer’s disease (AD), and Huntington’s disease. Hence, the key molecule that can regulate the expression of NTFs is an important target for gene therapy coupling adeno-associated virus vector (AAV) gene. We have previously reported that the Ras homolog protein enriched in brain (Rheb)–mammalian target of rapamycin complex 1 (mTORC1) axis plays a vital role in preventing neuronal death in the brain of AD and PD patients. AAV transduction using a constitutively active form of Rheb exerts a neuroprotective effect through the upregulation of NTFs, thereby promoting the neurotrophic interaction between astrocytes and neurons in AD conditions. These findings suggest the role of Rheb as an important regulator of the regulatory system of NTFs to treat neurodegenerative diseases. In this review, we present an overview of the role of Rheb in neurodegenerative diseases and summarize the therapeutic potential of AAV serotype 1 (AAV1)-Rheb(S16H) transduction in the treatment of neurodegenerative disorders, focusing on diseases, such as AD and PD.

G3BPs tether the TSC complex to lysosomes and suppress mTORC1 signaling

Ras GTPase-activating protein-binding proteins 1 and 2 (G3BP1 and G3BP2, respectively) are widely recognized as core components of stress granules (SGs). We report that G3BPs reside at the cytoplasmic surface of lysosomes. They act in a non-redundant manner to anchor the tuberous sclerosis complex (TSC) protein complex to lysosomes and suppress activation of the metabolic master regulator mechanistic target of rapamycin complex 1 (mTORC1) by amino acids and insulin. Like the TSC complex, G3BP1 deficiency elicits phenotypes related to mTORC1 hyperactivity. In the context of tumors, low G3BP1 levels enhance mTORC1-driven breast cancer cell motility and correlate with adverse outcomes in patients. Furthermore, G3bp1 inhibition in zebrafish disturbs neuronal development and function, leading to white matter heterotopia and neuronal hyperactivity. Thus, G3BPs are not only core components of SGs but also a key element of lysosomal TSC-mTORC1 signaling.

Nutritional Support of Neurodevelopment and Cognitive Function in Infants and Young Children-An Update and Novel Insights

Proper nutrition is crucial for normal brain and neurocognitive development. Failure to optimize neurodevelopment early in life can have profound long-term implications for both mental health and quality of life. Although the first 1000 days of life represent the most critical period of neurodevelopment, the central and peripheral nervous systems continue to develop and change throughout life. All this time, development and functioning depend on many factors, including adequate nutrition. In this review, we outline the role of nutrients in cognitive, emotional, and neural development in infants and young children with special attention to the emerging roles of polar lipids and high quality (available) protein. Furthermore, we discuss the dynamic nature of the gut-brain axis and the importance of microbial diversity in relation to a variety of outcomes, including brain maturation/function and behavior are discussed. Finally, the promising therapeutic potential of psychobiotics to modify gut microbial ecology in order to improve mental well-being is presented. Here, we show that the individual contribution of nutrients, their interaction with other micro- and macronutrients and the way in which they are organized in the food matrix are of crucial importance for normal neurocognitive development.

Prohibitin regulates mTOR pathway via interaction with FKBP8

The ability of tumor cells to sustain continuous proliferation is one of the major characteristics of cancer. The activation of oncogenes and the mutation or inactivation of tumor suppressor genes ensure the rapid proliferation of tumor cells. The PI3K-Akt-mTOR axis is one of the most frequently modified signaling pathways whose activation sustains cancer growth. Unsurprisingly, it is also one of the most commonly attempted targets for cancer therapy. FK506 binding protein 8 (FKBP8) is an intrinsic inhibitor of mTOR kinase that also exerts an anti-apoptotic function. We aimed to explain these contradictory aspects of FKBP8 in cancer by identifying a "switch" type regulator. We identified through immunoprecipitation-mass spectrometry-based proteomic analysis that the mitochondrial protein prohibitin 1 (PHB1) specifically interacts with FKBP8. Furthermore, the downregulation of PHB1 inhibited the proliferation of ovarian cancer cells and the mTOR signaling pathway, whereas the FKBP8 level in the mitochondria was substantially reduced. Moreover, concomitant with these changes, the interaction between FKBP8 and mTOR substantially increased in the absence of PHB1. Collectively, our finding highlights PHB1 as a potential regulator of FKBP8 because of its subcellular localization and mTOR regulating role.

The Rag GTPase Regulates the Dynamic Behavior of TSC Downstream of Both Amino Acid and Growth Factor Restriction

The dysregulation of the metabolic regulator TOR complex I (TORC1) contributes to a wide array of human pathologies. Tuberous sclerosis complex (TSC) is a potent inhibitor of TORC1. Here, we demonstrate that the Rag GTPase acts in both the amino-acid-sensing and growth factor signaling pathways to control TORC1 activity through the regulation of TSC dynamics in HeLa cells and Drosophila. We find that TSC lysosomal-cytosolic exchange increases in response to both amino acid and growth factor restriction. Moreover, the rate of exchange mirrors TSC function, with depletions of the Rag GTPase blocking TSC lysosomal mobility and rescuing TORC1 activity. Finally, we show that the GATOR2 complex controls the phosphorylation of TSC2, which is essential for TSC exchange. Our data support the model that the amino acid and growth factor signaling pathways converge on the Rag GTPase to inhibit TORC1 activity through the regulation of TSC dynamics.

Dietary Energy Modulation and Autophagy: Exploiting Metabolic Vulnerabilities to Starve Cancer

Cancer cells experience unique and dynamic shifts in their metabolic function in order to survive, proliferate, and evade growth inhibition in the resource-scarce tumor microenvironment. Therefore, identification of pharmacological agents with potential to reprogram cancer cell metabolism may improve clinical outcomes in cancer therapy. Cancer cells also often exhibit an increased dependence on the process known as autophagy, both for baseline survival and as a response to stressors such as chemotherapy or a decline in nutrient availability. There is evidence to suggest that this increased dependence on autophagy in cancer cells may be exploitable clinically by combining autophagy modulators with existing chemotherapies. In light of the increased metabolic rate in cancer cells, interest is growing in approaches aimed at "starving" cancer through dietary and pharmacologic interventions that reduce availability of nutrients and pro-growth hormonal signals known to promote cancer progression. Several dietary approaches, including chronic calorie restriction and multiple forms of fasting, have been investigated for their potential anti-cancer benefits, yielding promising results in animal models. Induction of autophagy in response to dietary energy restriction may underlie some of the observed benefit. However, while interventions based on dietary energy restriction have demonstrated safety in clinical trials, uncertainty remains regarding translation to humans as well as feasibility of achieving compliance due to the potential discomfort and weight loss that accompanies dietary restriction. Further induction of autophagy through dietary or pharmacologic metabolic reprogramming interventions may enhance the efficacy of autophagy inhibition in the context of adjuvant or neo-adjuvant chemotherapy. Nonetheless, it remains unclear whether therapeutic agents aimed at autophagy induction, autophagy inhibition, or both are a viable therapeutic strategy for improving cancer outcomes. This review discusses the literature available for the therapeutic potential of these approaches.

Inflammatory and immune mechanisms underlying epileptogenesis and epilepsy: From pathogenesis to treatment target

Epilepsy is a brain disease associated with epileptic seizures as well as with neurobehavioral outcomes of this condition. In the last century, inflammation emerged as a crucial factor in epilepsy etiology. Various brain insults through activation of neuronal and non-neuronal brain cells initiate a series of inflammatory events. Growing observations strongly suggest that abnormal activation of critical inflammatory processes contributes to epileptogenesis, a gradual process by which a normal brain transforms into the epileptic brain. Increased knowledge of inflammatory pathways in epileptogenesis has unveiled mechanistic targets for novel antiepileptic therapies. Molecules specifically targeting the pivotal inflammatory pathways may serve as promising candidates to halt the development of epilepsy. The present paper reviews the pieces of evidence conceptually supporting the potential role of inflammatory mechanisms and the relevant blood-brain barrier (BBB) disruption in epileptogenesis. Also, it discusses the mechanisms underlying inflammation-induced neuronal-glial network impairment and highlights innovative neuroregulatory actions of typical inflammatory molecules. Finally, it presents a brief analysis of observations supporting the therapeutic role of inflammation-targeting tiny molecules in epileptic seizures.

Mechanisms of Lifespan Regulation by Calorie Restriction and Intermittent Fasting in Model Organisms

Genetic and pharmacological interventions have successfully extended healthspan and lifespan in animals, but their genetic interventions are not appropriate options for human applications and pharmacological intervention needs more solid clinical evidence. Consequently, dietary manipulations are the only practical and probable strategies to promote health and longevity in humans. Caloric restriction (CR), reduction of calorie intake to a level that does not compromise overall health, has been considered as being one of the most promising dietary interventions to extend lifespan in humans. Although it is straightforward, continuous reduction of calorie or food intake is not easy to practice in real lives of humans. Recently, fasting-related interventions such as intermittent fasting (IF) and time-restricted feeding (TRF) have emerged as alternatives of CR. Here, we review the history of CR and fasting-related strategies in animal models, discuss the molecular mechanisms underlying these interventions, and propose future directions that can fill the missing gaps in the current understanding of these dietary interventions. CR and fasting appear to extend lifespan by both partially overlapping common mechanisms such as the target of rapamycin (TOR) pathway and circadian clock, and distinct independent mechanisms that remain to be discovered. We propose that a systems approach combining global transcriptomic, metabolomic, and proteomic analyses followed by genetic perturbation studies targeting multiple candidate pathways will allow us to better understand how CR and fasting interact with each other to promote longevity.

Signaling Network of Forkhead Family of Transcription Factors (FOXO) in Dietary Restriction

Dietary restriction (DR), which is defined as a reduction of particular or total nutrient intake without causing malnutrition, has been proved to be a robust way to extend both lifespan and health-span in various species from yeast to mammal. However, the molecular mechanisms by which DR confers benefits on longevity were not yet fully elucidated. The forkhead box O transcription factors (FOXOs), identified as downstream regulators of the insulin/IGF-1 signaling pathway, control the expression of many genes regulating crucial biological processes such as metabolic homeostasis, redox balance, stress response and cell viability and proliferation. The activity of FOXOs is also mediated by AMP-activated protein kinase (AMPK), sirtuins and the mammalian target of rapamycin (mTOR). Therefore, the FOXO-related pathways form a complex network critical for coordinating a response to environmental fluctuations in order to maintain cellular homeostasis and to support physiological aging. In this review, we will focus on the role of FOXOs in different DR interventions. As different DR regimens or calorie (energy) restriction mimetics (CRMs) can elicit both distinct and overlapped DR-related signaling pathways, the benefits of DR may be maximized by combining diverse forms of interventions. In addition, a better understanding of the precise role of FOXOs in different mechanistic aspects of DR response would provide clear cellular and molecular insights on DR-induced increase of lifespan and health-span.

Direct physical interaction of active Ras with mSIN1 regulates mTORC2 signaling

Background

The mechanistic (or mammalian) target of rapamycin (mTOR), a Ser/Thr kinase, associates with different subunits forming two functionally distinct complexes, mTORC1 and mTORC2, regulating a diverse set of cellular functions in response to growth factors, cellular energy levels, and nutrients. The mechanisms regulating mTORC1 activity are well characterized; regulation of mTORC2 activity, however, remains obscure. While studies conducted in Dictyostelium suggest a possible role of Ras protein as a potential upstream regulator of mTORC2, definitive studies delineating the underlying molecular mechanisms, particularly in mammalian cells, are still lacking.

Methods

Protein levels were measured by Western blotting and kinase activity of mTORC2 was analyzed by in vitro kinase assay. In situ Proximity ligation assay (PLA) and co-immunoprecipitation assay was performed to detect protein-protein interaction. Protein localization was investigated by immunofluorescence and subcellular fractionation while cellular function of mTORC2 was assessed by assaying extent of cell migration and invasion.

Results

Here, we present experimental evidence in support of the role of Ras activation as an upstream regulatory switch governing mTORC2 signaling in mammalian cancer cells. We report that active Ras through its interaction with mSIN1 accounts for mTORC2 activation, while disruption of this interaction by genetic means or via peptide-based competitive hindrance, impedes mTORC2 signaling.

Conclusions

Our study defines the regulatory role played by Ras during mTORC2 signaling in mammalian cells and highlights the importance of Ras-mSIN1 interaction in the assembly of functionally intact mTORC2.

Ketogenic Diet and Skeletal Muscle Hypertrophy: A Frenemy Relationship?

Ketogenic diet (KD) is a nutritional regimen characterized by a high-fat and an adequate protein content and a very low carbohydrate level (less than 20 g per day or 5% of total daily energy intake). The insufficient level of carbohydrates forces the body to primarily use fat instead of sugar as a fuel source. Due to its characteristic, KD has often been used to treat metabolic disorders, obesity, cardiovascular disease, and type 2 diabetes. Skeletal muscle constitutes 40% of total body mass and is one of the major sites of glucose disposal. KD is a well-defined approach to induce weight loss, with its role in muscle adaptation and muscle hypertrophy less understood. Considering this lack of knowledge, the aim of this review was to examine the scientific evidence about the effects of KD on muscle hypertrophy. We first described the mechanisms of muscle hypertrophy per se, and secondly, we discussed the characteristics and the metabolic function of KD. Ultimately, we provided the potential mechanism that could explain the influence of KD on skeletal muscle hypertrophy.

Fasting and rapamycin: diabetes versus benevolent glucose intolerance

Rapamycin (Sirolimus) slows aging, extends life span, and prevents age-related diseases, including diabetic complications such as retinopathy. Puzzlingly, rapamycin can induce insulin sensitivity, but may also induce insulin resistance or glucose intolerance without insulin resistance. This mirrors the effect of fasting and very low calorie diets, which improve insulin sensitivity and reverse type 2 diabetes, but also can cause a form of glucose intolerance known as benevolent pseudo-diabetes. There is no indication that starvation (benevolent) pseudo-diabetes is detrimental. By contrast, it is associated with better health and life extension. In transplant patients, a weak association between rapamycin/everolimus use and hyperglycemia is mostly due to a drug interaction with calcineurin inhibitors. When it occurs in cancer patients, the hyperglycemia is mild and reversible. No hyperglycemic effects of rapamycin/everolimus have been detected in healthy people. For antiaging purposes, rapamycin/everolimus can be administrated intermittently (e.g., once a week) in combination with intermittent carbohydrate restriction, physical exercise, and metformin.

Effects of jugular infusions of isoleucine, leucine, methionine, threonine, and other amino acids on insulin and glucagon concentrations, mammalian target of rapamycin (mTOR) signaling, and lactational performance in goats

The supply and profile of absorbed AA may affect milk protein synthesis through hormonal changes and mammalian target of rapamycin (mTOR) signaling pathways; and Ile, Leu, Met, and Thr (ILMT) are the 4 AA that have been reported to have the greatest effect on mammary mTOR signaling. The extent to which ILMT and the other remaining AA (RAA) differ in their effects on milk protein synthesis needs to be systematically investigated. In this study, 5 lactating goats, averaging 120 ± 10 d in milk, fitted with jugular vein and carotid artery catheters, were fasted for 24 h, followed by intravenous infusions of a mixture containing AA and glucose for 8 h in a 5 × 5 Latin square design. The AA mixtures were formulated according to the profile of casein. The amounts of AA infused were calculated based on supplies of AA when metabolizable protein (MP) was at requirement (MR). Treatments were an infusate containing glucose without AA (NTAA); an infusate containing 3 × the MR of Ile, Leu, Met and Thr (3F0R); and infusates containing 3F0R plus 1, 2, or 3 × MR of RAA (3F1R, 3F2R, and 3F3R, respectively) according to amounts provided when fed to meet MP requirements for maintenance and lactation for each goat. Milk, arterial blood, and mammary tissue samples were collected immediately after halting the infusion. Relative to NTAA, supplementation of ILMT tended to increase milk protein production and plasma glucose concentrations, and increased milk and lactose production, but had no effects on production or content of milk fat. Graded supplementation of RAA tended to quadratically affect production of milk and lactose. Arterial glucose and glucagon concentrations decreased linearly, and plasma insulin concentrations decreased quadratically with increased RAA. Mammary p70-S6K1 phosphorylation was decreased by addition of ILMT compared with NTAA but increased linearly with increased RAA infusion. Furthermore, EIF4EBP1 gene expression was much lower for 3F-treated goats than for the NTAA treatment. Both MTOR and RPS6KB1 gene expressions were decreased quadratically with increased RAA supply. These results suggested that short-term milk protein yield tended to be increased by elevated ILMT availability, and this trend was not explained by variations in mammary mTOR signaling or pancreatic hormone secretions, whereas graded increase of RAA in combination with ILMT appeared to regulate the efficiency of conversion of glucose to lactose in a manner not involving milk protein production.

17β‑Estradiol protects against interleukin‑1β‑induced apoptosis in rat nucleus pulposus cells via the mTOR/caspase‑3 pathway

Intervertebral disc degeneration (IVDD) is the main pathological basis of spinal degenerative diseases, and aberrant apoptosis of nucleus pulposus cells (NPCs) is the main cellular process that causes IVDD. In our previous studies, 17β-estradiol (E₂) was demonstrated to protect rat NPCs from interleukin-1β (IL-1β)-induced apoptosis via the PI3K/Akt signaling pathway. However, the downstream signaling pathway of PI3K/Akt is currently unclear. The present study aimed to explore the signaling pathways that are downstream of the PI3K/Akt pathway, including mTOR, NF-κB and glycogen synthase kinase-3β (GSK-3β). Annexin V/propidium iodide double staining was used to determine the incidence of apoptosis. Cell Counting kit-8 and MTS assays were used to determine the proliferation and viability of NPCs, respectively. Cellular binding was evaluated using a cell-collagen binding assay. Western blotting was used to determine the protein expression levels of mTOR, NF-κB and GSK-3β, and their phosphorylation levels, as well as the expression levels of active caspase-3. The results revealed that IL-1β induced NPC apoptosis and increased the early apoptotic rate of NPCs. However, E₂ reduced the early apoptosis of NPCs induced by IL-1β. In addition, E₂ suppressed the decrease in cell viability and binding ability caused by IL-1β cytotoxicity. Western blotting revealed that E₂ also reduced the expression of activated caspase-3, and increased the expression of activated mTOR. As a specific inhibitor of mTOR, rapamycin effectively attenuated the effects of E₂. These findings indicated that E₂ protected NPCs against apoptosis via activation of the mTOR/caspase-3 pathway.

Snapshot: Implications for mTOR in Aging-related Ischemia/Reperfusion Injury

Aging may aggravate the damage and dysfunction of different components of multiorgan and thus increasing multiorgan ischemia/reperfusion (IR) injury. IR injury occurs in many organs and tissues, which is a major cause of morbidity and mortality worldwide. The kinase mammalian target of rapamycin (mTOR), an atypical serine/threonine protein kinase, involves in the pathophysiological process of IR injury. In this review, we first briefly introduce the molecular features of mTOR, the association between mTOR and aging, and especially its role on autophagy. Special focus is placed on the roles of mTOR during ischemic and IR injury. We then clarify the association between mTOR and conditioning phenomena. Following this background, we expand our discussion to potential future directions of research in this area. Collectively, information reviewed herein will serve as a comprehensive reference for the actions of mTOR in IR injury and may be significant for the design of future research and increase the potential of mTOR as a therapeutic target.

Hypothalamic PDE3B deficiency alters body weight and glucose homeostasis in mouse

Pharmacological studies have suggested hypothalamic phosphodiesterase-3B to mediate leptin and insulin action in regulation of energy homeostasis. Whereas Pde3b-null mice show altered energy homeostasis, it is unknown whether this is due to ablation of Pde3b in the hypothalamus. Thus, to address the functional significance of hypothalamic phosphodiesterase-3B, we used Pde3bflox/flox and Nkx2.1-Cre mice to generate Pde3b Nkx2.1KD mice that showed 50% reduction of phosphodiesterase-3B in the hypothalamus. To determine the effect of partial ablation of phosphodiesterase-3B in the hypothalamus on energy and glucose homeostasis, males and females were subjected to either a low- or high-fat diet for 19–21 weeks. Only female but not male Pde3b Nkx2.1KD mice on the low-fat diet showed increased body weight from 13 weeks onward with increased food intake, decreased fat pad weights and hypoleptinemia. Glucose tolerance was improved in high-fat diet-fed male Pde3b Nkx2.1KD mice in association with decreased phosphoenolpyruvate carboxykinase-1 and glucose-6-phosphatase mRNA levels in the liver. Also, insulin sensitivity was increased in male Pde3b Nkx2.1KD mice on the low-fat diet. Changes in body weight or in glucose homeostasis were not associated with any alteration in hypothalamic proopiomelanocortin, neuropepide Y and agouti-related peptide mRNA levels. These results suggest that partial loss of phosphodiesterase-3B in the hypothalamus produces a sex-specific response in body weight and glucose homeostasis, and support a role, at least in part, for hypothalamic phosphodiesterase-3B in regulation of energy and glucose homeostasis in mice.

Carboxyl-Terminal Modulator Protein Ameliorates Pathological Cardiac Hypertrophy by Suppressing the Protein Kinase B Signaling Pathway

Background

Carboxyl‐terminal modulator protein (CTMP) has been implicated in cancer, brain injury, and obesity. However, the role of CTMP in pathological cardiac hypertrophy has not been identified.

Methods and Results

In this study, decreased expression of CTMP was observed in both human failing hearts and murine hypertrophied hearts. To further explore the potential involvement of CTMP in pathological cardiac hypertrophy, cardiac‐specific CTMP knockout and overexpression mice were generated. In vivo experiments revealed that CTMP deficiency exacerbated the cardiac hypertrophy, fibrosis, and function induced by pressure overload, whereas CTMP overexpression alleviated the response to hypertrophic stimuli. Consistent with the in vivo results, adenovirus‐mediated gain‐of‐function or loss‐of‐function experiments showed that CTMP also exerted a protective effect against hypertrophic responses to angiotensin II in vitro. Mechanistically, CTMP ameliorated pathological cardiac hypertrophy through the blockade of the protein kinase B signaling pathway. Moreover, inhibition of protein kinase B activation with LY294002 rescued the deteriorated effect in aortic banding–treated cardiac‐specific CTMP knockout mice.

Conclusions

Taken together, these findings imply, for the first time, that increasing the cardiac expression of CTMP may be a novel therapeutic strategy for pathological cardiac hypertrophy.

Bioinformatics functional analysis of let-7a, miR-34a, and miR-199a/b reveals novel insights into immune system pathways and cancer hallmarks for hepatocellular carcinoma

Let-7a, miR-34a, and miR-199 a/b have gained a great attention as master regulators for cellular processes. In particular, these three micro-RNAs act as potential onco-suppressors for hepatocellular carcinoma. Bioinformatics can reveal the functionality of these micro-RNAs through target prediction and functional annotation analysis. In the current study, in silico analysis using innovative servers (miRror Suite, DAVID, miRGator V3.0, GeneTrail) has demonstrated the combinatorial and the individual target genes of these micro-RNAs and further explored their roles in hepatocellular carcinoma progression. There were 87 common target messenger RNAs (p ≤ 0.05) that were predicted to be regulated by the three micro-RNAs using miRror 2.0 target prediction tool. In addition, the functional enrichment analysis of these targets that was performed by DAVID functional annotation and REACTOME tools revealed two major immune-related pathways, eight hepatocellular carcinoma hallmarks-linked pathways, and two pathways that mediate interconnected processes between immune system and hepatocellular carcinoma hallmarks. Moreover, protein-protein interaction network for the predicted common targets was obtained by using STRING database. The individual analysis of target genes and pathways for the three micro-RNAs of interest using miRGator V3.0 and GeneTrail servers revealed some novel predicted target oncogenes such as SOX4, which we validated experimentally, in addition to some regulated pathways of immune system and hepatocarcinogenesis such as insulin signaling pathway and adipocytokine signaling pathway. In general, our results demonstrate that let-7a, miR-34a, and miR-199 a/b have novel interactions in different immune system pathways and major hepatocellular carcinoma hallmarks. Thus, our findings shed more light on the roles of these miRNAs as cancer silencers.

Milk fat globule membrane protein promotes C2C12 cell proliferation through the PI3K/Akt signaling pathway

Milk fat globule membrane (MFGM) protein is known to have several health benefits, including an anti-sarcopenia effect; however, its mechanism is unclear. The aim of this study was to investigate the potential mechanism of action of the MFGM protein. The MFGM protein was extracted and separated into 4 fractions, and Fraction 2 (57% of total MFGM) demonstrated the greatest effect on C₂C₁₂ cell proliferation. Milk fat globule-EGF factor 8 (MFG-E8) accounted for 82.35% of the MFGM protein. The effects of whole Fraction 2 (100μg/mL, 200μg/mL and 300μg/mL) on cell proliferation and morphology were measured. Using qRT-PCR or a Western blot assay, several regulatory factors, e.g., PI3K P85α, p-pI3K p85α (Tyr 508), Akt, p-Akt (Ser 473), mTOR and p-mTOR (Ser 2448), were measured in cells incubated with 200μg/mL of Fraction 2 with or without wortmannin. The results demonstrated that Fraction 2 induced C₂C₁₂ cell proliferation in a dose-dependent manner, upregulated the mRNA expression of mTOR and p70S6K, and activated PI3K, Akt, mTOR and P70S6K phosphorylation; however, Fraction 2 inhibited FOXO3a and 4E-BP. The results demonstrate that the MFGM protein, predominantly MFG-E8, promotes cell proliferation through the PI3K/Akt/mTOR signaling pathway. This study elucidated the molecular mechanism of the MFGM protein, primarily MFG-E8, in promoting C₂C₁₂ cell proliferation via the PI3K/Akt/mTOR/P70S6K signal pathway.

Overexpression of RHEB is associated with metastasis and poor prognosis in hepatocellular carcinoma

Aberrant expression of Ras homolog enriched in brain (RHEB) has been observed in a variety of cancer tissues and is closely associated with clinicopathological features. However, the expression profile of RHEB in patients with hepatocellular carcinoma (HCC) and its clinical signature with underlying mechanisms have not been explored thus far. To analyze the association between RHEB expression and clinicopathological features, the RHEB expression levels were determined in the present study using gene microarrays, immunohistochemistry and western blotting in 60 liver cancer tissues and 35 normal liver tissues. Downregulation of RHEB expression in liver cancer cell lines was achieved by RNA interfering technology to explore its biological function in HCC. RHEB expression was high in liver cancer tissues, with an increase of 2.00±0.19-fold compared with normal tissues and of 2.00±0.27-fold compared with adjacent non-cancer tissues. RHEB expression increased along with the clinical staging of HCC, and the overall survival and mortality of patients were closely correlated to RHEB levels, micro-vascular invasion, hepatitis B virus-DNA titer, tumor differentiation and pathological satellites (P<0.05). After knocking down RHEB in SMMC-7721 cells, the growth of liver cancer cells was significantly reduced. The majority of cells were blocked in S-phase, and their colony-forming and proliferating abilities significantly decreased (P<0.05). In vivo, upon downregulation of RHEB expression, the tumorigenic ability of HCC significantly decreased (P<0.05). These data suggest that RHEB expression is a significant prognostic factor and may be important in HCC cell growth. The present study highlights the importance of RHEB as a novel prognostic marker of HCC.

Effects of dietary poly-β-hydroxybutyrate (PHB) on microbiota composition and the mTOR signaling pathway in the intestines of litopenaeus vannamei

Poly-β-hydroxybutyrate (PHB) is a natural polymer of the short chain fatty acid β-hydroxybutyrate, which acts as a microbial control agent. The mammalian target of the rapamycin (mTOR) signaling pathway plays a crucial role in intestine inflammation and epithelial morphogenesis. In this study, we examined the composition of intestine microbiota, and mTOR signaling-related gene expression in Pacific white shrimp Litopenaeus vannamei fed diets containing different levels of PHB: 0% (Control), 1% (PHB1), 3% (PHB3), and 5% (PHB5) (w/w) for 35 days. High-throughput sequencing analysis revealed that dietary PHB altered the composition and diversity of intestine microbiota, and that the microbiota diversity decreased with the increasing doses of PHB. Specifically, dietary PHB increased the relative abundance of Proteobacteria and Tenericutes in the PHB1 and PHB5 groups, respectively, and increased that of Gammaproteobacteria in the three PHB groups. Alternatively, PHB decreased Alphaproteobacteria in the PHB3 and PHB5 groups. At the genus level, dietary PHB increased the abundance of beneficial bacteria, such as Bacillus, Lactobacillus, Lactococcus, Clostridium, and Bdellovibrio. The relative mRNA expression levels of the mTOR signaling-related genes TOR, 4E-BP, eIF4E1α, and eIF4E2 all increased in the three PHB treatment groups. These results revealed that dietary PHB supplementation had a beneficial effect on intestine health of L. vannamei by modulating the composition of intestine microbiota and activating mTOR signaling.

Non-26S Proteasome Endomembrane Trafficking Pathways in ABA Signaling

The phytohormone abscisic acid (ABA) is a vital endogenous messenger that regulates diverse physiological processes in plants. The regulation of ABA signaling has been well studied at both the transcriptional and translational levels. Post-translational modification of key regulators in ABA signaling by the 26S ubiquitin proteasome pathway is well known. Recently, increasing evidence demonstrates that atypical turnover of key regulators by the endocytic trafficking pathway and autophagy also play vital roles in ABA perception, signaling, and action. We summarize and synthesize here recent findings in the field of ABA signaling.

Mechanisms contributing to cardiac remodelling

Cardiac remodelling is classified as physiological (in response to growth, exercise and pregnancy) or pathological (in response to inflammation, ischaemia, ischaemia/reperfusion (I/R) injury, biomechanical stress, excess neurohormonal activation and excess afterload). Physiological remodelling of the heart is characterized by a fine-tuned and orchestrated process of beneficial adaptations. Pathological cardiac remodelling is the process of structural and functional changes in the left ventricle (LV) in response to internal or external cardiovascular damage or influence by pathogenic risk factors, and is a precursor of clinical heart failure (HF). Pathological remodelling is associated with fibrosis, inflammation and cellular dysfunction (e.g. abnormal cardiomyocyte/non-cardiomyocyte interactions, oxidative stress, endoplasmic reticulum (ER) stress, autophagy alterations, impairment of metabolism and signalling pathways), leading to HF. This review describes the key molecular and cellular responses involved in pathological cardiac remodelling.

Insulin Regulation of Proteostasis and Clinical Implications

Maintenance and modification of the cellular proteome are at the core of normal cellular physiology. Although insulin is well known for its control of glucose homeostasis, its critical role in maintaining proteome homeostasis (proteostasis) is less appreciated. Insulin signaling regulates protein synthesis and degradation as well as posttranslational modifications at the tissue level and coordinates proteostasis at the organism level. Here, we review regulation of proteostasis by insulin in postabsorptive, postprandial, and diabetic states. We present the effects of insulin on amino acid flux in skeletal muscle and splanchnic tissues, the regulation of protein quality control, and turnover of mitochondrial protein pools in humans. We also review the current evidence for the mechanistic control of proteostasis by insulin and insulin-like growth factor 1 receptors based on preclinical studies. Finally, we discuss irreversible posttranslational modifications of the proteome in diabetes and how future investigations will provide new insights into mechanisms of diabetic complications.

Development of a new analog of SGK1 inhibitor and its evaluation as a therapeutic molecule of colorectal cancer

Colorectal cancer (CRC) is one of the most leading causes of cancer-related death worldwide. The serum and glucocorticoid inducible kinase SGK1 is highly expressed and involved in several tumors. GSK650394, a SGK1 inhibitor, has been proved to be effective in impeding tumor growth in vitro. In this study, we developed a novel analog of GSK650394, and evaluated its effects on CRC cells and tumor growth both in vitro and in vivo. HCT116 cells were treated with a concentration gradient of new developed compounds and cholecystokinin octapeptide (CCK-8) assay was used to calculate the IC50 value of every analog. Cell proliferation analysis was estimated from EdU staining and flow cytometry in vitro, and immunohistochemistry of Ki67 and PCNA in vivo. Cell migration analysis was examined using the transwell assay. In vivo tumor growth was determined in athymic nude mice by injecting the HCT116 cells in the subcutaneous tissue, followed by the injection of QGY-5-114-A. We found that new developed GSK650394 analog QGY-5-114-A has lower IC50 value, and treatment with QGY-5-114-A significantly inhibited CRC cell proliferation and migration in vitro. Besides that, colonic tumor growth was also dramatically restricted by QGY-5-114-A in vivo. In conclusion, pharmacological treatment with QGY-5-114-A impedes CRC tumor cell proliferation, migration and tumor growth.

Formal Modeling of mTOR Associated Biological Regulatory Network Reveals Novel Therapeutic Strategy for the Treatment of Cancer

Cellular homeostasis is a continuous phenomenon that if compromised can lead to several disorders including cancer. There is a need to understand the dynamics of cellular proliferation to get deeper insights into the prevalence of cancer. Mechanistic Target of Rapamycin (mTOR) is implicated as the central regulator of the metabolic pathway involved in growth whereas its two distinct complexes mTORC1 and mTORC2 perform particular functions in cellular propagation. To date, mTORC1 is a well defined therapeutic target to inhibit uncontrolled cell division, while the role of mTORC2 is not well characterized. Therefore, the current study is designed to understand the signaling dynamics of mTOR and its partner proteins such as PI3K, PTEN, mTORC2, PKB (Akt), mTORC1, and FOXO. For this purpose, a qualitative model of mTOR-associated Biological Regulatory Network (BRN) is constructed to predict its regulatory behaviors which may not be predictable otherwise. The depleted expression of PTEN and FOXO along with the overexpression of PI3K, mTORC2, mTORC1 and Akt is predicted as a stable steady state which is in accordance with their observed expression levels in the progression of various cancers. The qualitative model also predicts the homeostasis of all the entities in the form of qualitative cycles. The significant qualitative (discrete) cycle is identified by analyzing betweenness centralities of the qualitative (discrete) states. This cycle is further refined as a linear hybrid automaton model with the production (activation) and degradation (inhibition) time delays in order to analyze the real-time constraints for its existence. The analysis of the hybrid model provides a formal proof that during homeostasis the inhibition time delay of Akt is less than the inhibition time delay of mTORC2. In conclusion, our observations characterize that in homeostasis Akt is degraded with a faster rate than mTORC2 which suggests that the inhibition of Akt along with the activation of mTORC2 may be a better therapeutic strategy for the treatment of cancer.

Gromoff E, Wang Y, Maier W, Baumeister R. C. elegans DAF-16/FOXO interacts with TGF-ß/BMP signaling to induce germline tumor formation via mTORC1 activation

Activation of the FOXO transcription factor DAF-16 by reduced insulin/IGF signaling (IIS) is considered to be beneficial in C. elegans due to its ability to extend lifespan and to enhance stress resistance. In the germline, cell-autonomous DAF-16 activity prevents stem cell proliferation, thus acting tumor-suppressive. In contrast, hypodermal DAF-16 causes a tumorous germline phenotype characterized by hyperproliferation of the germline stem cells and rupture of the adjacent basement membrane. Here we show that cross-talk between DAF-16 and the transforming growth factor ß (TGFß)/bone morphogenic protein (BMP) signaling pathway causes germline hyperplasia and results in disruption of the basement membrane. In addition to activating MADM/NRBP/hpo-11 gene alone, DAF-16 also directly interacts with both R-SMAD proteins SMA-2 and SMA-3 in the nucleus to regulate the expression of mTORC1 pathway. Knocking-down of BMP genes or each of the four target genes in the hypodermis was sufficient to inhibit germline proliferation, indicating a cell-non-autonomously controlled regulation of stem cell proliferation by somatic tissues. We propose the existence of two antagonistic DAF-16/FOXO functions, a cell-proliferative somatic and an anti-proliferative germline activity. Whereas germline hyperplasia under reduced IIS is inhibited by DAF-16 cell-autonomously, activation of somatic DAF-16 in the presence of active IIS promotes germline proliferation and eventually induces tumor-like germline growth. In summary, our results suggest a novel pathway crosstalk of DAF-16 and TGF-ß/BMP that can modulate mTORC1 at the transcriptional level to cause stem-cell hyperproliferation. Such cell-type specific differences may help explaining why human FOXO activity is considered to be tumor-suppressive in most contexts, but may become oncogenic, e.g. in chronic and acute myeloid leukemia.

The transcription factor FOXO is a well-known tumor suppressor whose activity is controlled by nutrients and stress signaling. In the roundworm C. elegans, the activity of the FOXO protein DAF-16 is best known for its beneficial role in stress response and long lifespan. However, FOXO proteins may also promote tumor cell growth and maintenance in chronic and acute myeloid leukemia, suggesting that may have different roles in distinct contexts. Previously we have shown that selective activation of DAF-16 in the epidermis causes a tumorous growth in the stem cells of the C. elegans germline. Now we demonstrate that this oncogenic activity of DAF-16 is mediated by interactions with the transforming growth factor (TGFß)/Bone Morphogenic protein (BMP) signaling pathway. In the epidermis, direct binding of DAF-16 and R-SMAD proteins of the BMP pathway helps to activate genes involved in the mTORC1 signaling pathway that is frequently activated in tumors. We propose that the transcription factor DAF-16/FOXO may be controlled in different ways in the stem cells, in which its activity normally prevents tumor formation, and in other tissues, in which defects in controlling its activity may result in overwriting the beneficial stem cell activity to eventually promote tumor cell growth.