Rapid activation of Akt2 is sufficient to stimulate GLUT4 translocation in 3T3-L1 adipocytes

Deciphering Akt activation: Insights from a mean-field model

Being at the right place at the right time is vital for any signalling system component. Akt/PKB is a well-known low-threshold switch in the mammalian insulin signalling pathway. The activation of Akt is essential for the uptake of glucose, however, data concerning this vital system is very sparse, particularly with regards to cellular location and activation state. Here we present a parsimonious mathematical model that captures the current experimental understanding of Akt dynamics. The system operates on two distinct timescales (signalling and physical transport), with the transportation of Akt constituting the rate-limiting step in most circumstances. The model outputs are consistent with observations of the steady state behaviour of the system and display the transient overshoot behaviour which is a necessary characteristic of the activation of Akt.

TMEM158 promotes ICC metastasis via inducing lactic acid mediated reduction of actin skeleton stiffness of ICC cells

INTRODUCTION

The survival rate of patients with intrahepatic cholangiocarcinoma (ICC) is extremely low mainly because of its high metastatic characteristic, pushing us to explore effective targets inhibiting the metastasis of ICC.

OBJECTIVES

To explore potential therapeutical targets to restrict the metastasis of ICC.

METHODS

The potential targets were screened via RNA sequencing and verified in cells and tissues. The prognostic value of TMEM158 was explored in ICC patients. The abilities of TMEM158 on affecting the metastasis of ICC were detected in cells and mice models. The cell actin skeleton stiffness was measured by phalloidin staining. The effect of TMEM158 on lactic acid (LA) generation was explored via metabolic flow and relative mechanism was detected by co-immunoprecipitation and immunofluorescence. The relationship between HIF-1A and TMEM158 was explored by dual luciferase reporter gene experiment.

RESULTS

TMEM158 was identified as a potential candidate over-expressed in ICC, especially with metastasis, that is linked to reduced overall survival. Besides, functional studies indicated that TMEM158 silencing inhibits ICC metastasis in vivo and in vitro through decreasing cell actin skeleton stiffness of ICC cells, and visa versa. Moreover, mechanically, lactic acid (LA) is validated as the bridge connecting TMEM158 and skeleton stiffness and TMEM158 induces the generation of LA via interaction with and activating Ras protein and subsequently enhancing glucose transporter 3 (Glut3) mediated glycolysis in ICC cells. Finally, HIF-1A directly targets the promoter region of TMEM158 and thus increases its level in ICC.

CONCLUSION

TMEM158 reduced the actin skeleton stiffness of ICC cells through activating Ras protein mediated generation of LA, which finally results in enhanced metastasis of ICC. Our work provides a preclinical evidence of concept for TMEM158 as a novel candidate inhibiting the metastasis of ICC.

The Central FacilitaTOR: Coordinating Transcription and Translation in Eukaryotes

One of the biggest challenges to eukaryotic gene expression is coordinating transcription in the nucleus and protein synthesis in the cytoplasm. However, little is known about how these major steps in gene expression are connected. The Target of Rapamycin (TOR) signaling pathway is crucial in connecting these critical phases of gene expression. Highly conserved among eukaryotic cells, TOR regulates growth, metabolism, and cellular equilibrium in response to changes in nutrients, energy levels, and stress conditions. This review examines the extensive role of TOR in gene expression regulation. We highlight how TOR is involved in phosphorylation, remodeling chromatin structure, and managing the factors that facilitate transcription and translation. Furthermore, the critical functions of TOR extend to processing RNA, assembling RNA-protein complexes, and managing their export from the nucleus, demonstrating its wide-reaching impact throughout the cell. Our discussion emphasizes the integral roles of TOR in bridging the processes of transcription and translation and explores how it orchestrates these complex cellular processes.

CD36 inhibition enhances the anti-proliferative effects of PI3K inhibitors in PTEN-loss anti-HER2 resistant breast cancer cells

BACKGROUND

HER2-positive patients comprise approximately 20% of breast cancer cases, with HER2-targeted therapy significantly improving progression-free and overall survival. However, subsequent reprogramed tumor progression due to PI3K signaling pathway activation by PIK3CA mutations and/or PTEN-loss cause anti-HER2 resistance. Previously, alpha isoform-specific PI3K inhibitors were shown to potentiate HER2-targeted therapy in breast cancer cells carrying PI3K pathway alterations with less potent effects on PTEN-loss than PIK3CA-mutant cells. Therefore, seeking for alternative combination therapy needs urgent attentions in PTEN-loss anti-HER2 resistant breast cancer.

METHODS

Since remodeling of fatty acid (FA) metabolism might contribute to HER-positive breast cancer and is triggered by the PI3K signal pathway, herein, we examined the effects of the inhibition of endogenous FA conversion, SCD-1 or exogenous FA transport, CD36, in combination with PI3K inhibitors (alpelisib and inavolisib) in anti-HER2 resistant PTEN-loss breast cancer cells.

RESULTS

The activated HER2/PI3K/AKT/mTOR signaling pathway positively correlated with SCD-1 and CD36 expression in PTEN-loss breast cancer cells. PI3K inhibition downregulated SCD-1, and accordingly, the addition of the SCD-1 inhibitor did not augment the antiproliferative effects of the PI3K inhibitors. CD36 was upregulated by blocking the PI3K signal pathway or limited serum supplementation, indicating that suppressing CD36 may decrease the excess transport of exogenous FA. The addition of the CD36 inhibitor synergistically enhanced the anti-proliferative effects of the PI3K inhibitors.

CONCLUSION

Simultaneously targeting the PI3K signaling pathway and exogenous FA uptake could potentially be advantageous for patients with PTEN-loss anti-HER2 resistant breast cancer.

mTOR Ser1261 is an AMPK-dependent phosphosite in mouse and human skeletal muscle not required for mTORC2 activity

The kinases AMPK, and mTOR as part of either mTORC1 or mTORC2, are major orchestrators of cellular growth and metabolism. Phosphorylation of mTOR Ser1261 is reportedly stimulated by both insulin and AMPK activation and a regulator of both mTORC1 and mTORC2 activity. Intrigued by the possibilities that Ser1261 might be a convergence point between insulin and AMPK signaling in skeletal muscle, we investigated the regulation and function of this site using a combination of human exercise, transgenic mouse, and cell culture models. Ser1261 phosphorylation on mTOR did not respond to insulin in any of our tested models, but instead responded acutely to contractile activity in human and mouse muscle in an AMPK activity-dependent manner. Contraction-stimulated mTOR Ser1261 phosphorylation in mice was decreased by Raptor muscle knockout (mKO) and increased by Raptor muscle overexpression, yet was not affected by Rictor mKO, suggesting most of Ser1261 phosphorylation occurs within mTORC1 in skeletal muscle. In accordance, HEK293 cells mTOR Ser1261Ala mutation strongly impaired phosphorylation of mTORC1 substrates but not mTORC2 substrates. However, neither mTORC1 nor mTORC2-dependent phosphorylations were affected in muscle-specific kinase-dead AMPK mice with no detectable mTOR Ser1261 phosphorylation in skeletal muscle. Thus, mTOR Ser1261 is an exercise but not insulin-responsive AMPK-dependent phosphosite in human and murine skeletal muscle, playing an unclear role in mTORC1 regulation but clearly not required for mTORC2 activity.

Immunometabolic profiling related with gestational diabetes mellitus: a nested case-control study of CD4+ T cell phenotypes and glycemic traits

AIMS

To investigate immunometabolic associations of CD4+ T cell phenotypes with gestational diabetes mellitus (GDM).

METHODS

A nested case-control study was conducted comprising 53 pairs of GDM patients and matched controls within a prospective cohort. Metabolomic signatures related to both CD4+ T cell phenotypes and glycemic traits among pregnant women were investigated by weighted gene co-expression network analysis (WGCNA). Multivariable-adjusted generalized linear models were used to explore the associations of CD4+ T cell phenotypes and selected metabolites with GDM. Mediation analysis was conducted to evaluate the mediating effect of selected metabolites on the relationship between CD4+ T cell phenotypes and glycemic traits.

RESULTS

Higher levels of Treg cells (OR per SD increment (95%CI): 0.57 (0.34, 0.95), p = 0.031) and increased expression of Foxp3 (OR per SD increment (95%CI): 0.59 (0.35, 0.97), p = 0.039) and GATA3 (OR per SD increment (95%CI): 0.42 (0.25, 0.72), p = 0.002) were correlated with a decreased risk of GDM. Plasma pyruvaldehyde, S-adenosylhomocysteine (SAH), bergapten, and 9-fluorenone mediated the association between Tregs and fasting plasma glucose (FPG), with mediation proportions of 46.9%, 39.6%, 52.4%, and 56.9%, respectively.

CONCLUSIONS

Treg cells and Foxp3 expressions were inversely associated with GDM risk, with potential metabolic mechanisms involving metabolites such as pyruvaldehyde and SAH.

Airborne polystyrene nanoplastics exposure leads to heart failure via ECM-receptor interaction and PI3K/AKT/BCL-2 pathways

Environmental contamination has been recognized as a significant threat to human well-being, and recent findings of microplastic presence in human cardiac tissues have raised concerns. However, research on the effects of airborne nanoplastics (NPs) on cardiac physiology remains limited. We utilized a comprehensive body exposure apparatus to simulate the impact of airborne polystyrene NPs pollution, focusing on understanding how airborne NPs affect cardiac morphology and function. Following two weeks of NPs exposure, mice exhibited a 23.89 ± 8.30 % reduction in heart mass, a 20.05 ± 2.97 % decrease in heart rate as detected, and a myocardial electrical conduction block. Echocardiography showed significant changes in cardiac contractility, with increases in cardiac ejection fraction and stroke volume of 13.00 ± 3.00 % and 43.00 ± 17.00 %, respectively. In addition, histologic assessments revealed signs of ventricular hypertrophy, ventricular myocardial hypertrophy, and myocardial necrotic fibrosis. Of particular interest, our mechanistic investigations highlighted the harmful effects of NPs on cardiac structure and function, mediated through extracellular matrix (ECM) receptor interactions and the PI3K/AKT/BCL-2 signaling pathway. The insights gained provide a foundation for understanding the risks posed by airborne NPs to human cardiac health, emphasizing the need for increased vigilance and implementation of mitigation strategies in environmental management.

The role of lipid-soluble vitamins on glucose transporter

Glucose is the primary source of energy for most of the cells and essential for basic functionalities of life's biochemical processes. Transportation of glucose via biological membranes is essential for life mediated by glucose transporters (GLUT) through facilitated diffusion. Glucose transporters perform a crucial role in maintaining normal health as they transfer the most essential molecules of life, glucose. There are 14 various types of glucose transporters that transport primarily glucose and fructose. GUTTs are trans-membrane proteins expressed in the plasma membrane that facilitate the entry of carbohydrate molecules inside the cells. These transporters provide the passage for the carbohydrate molecules, which undergo oxidation inside the cells and provide essential energy in the form of ATPs. Lipid-soluble vitamins, namely A, D, E, and K have been reported to play a key role in stimulating several glucose transporters. Supplementation of lipid-soluble vitamins stimulates the expression of glucose transporters, most importantly GLUT4, GLUT2, GLUT1, and GLUT3, which play a critical role in regulating glucose metabolism in muscle, liver, brain, and RBCs. For their ability to increase the expression of GLUTs, the lipid-soluble vitamins can be the potential micronutrient for combating various non-communicable diseases. The present article discusses the essential role of lipid-soluble vitamins in the regulation of glucose transporters.

Cooperative action of non-digestible oligosaccharides improves lipid metabolism of high-fat diet-induced mice

Non-digestible oligosaccharides are known to exert health-promoting effects. However, the specific mechanisms by which they regulate host physiology remain unclear. Understanding these mechanisms will facilitate the development of non-digestible oligosaccharide compositions that can achieve synergistic effects. This study selected three representative non-digestible oligosaccharides, namely xylo-oligosaccharides (XOS), galacto-oligosaccharides (GOS), and isomalto-oligosaccharides (IMO), to investigate their effects as dietary interventions on mice fed a high-fat diet. The results demonstrated that XOS and IMO synergistically mitigated weight gain and ectopic lipid deposition. Further analysis revealed that XOS significantly altered the composition of the gut microbiota, while IMO significantly enhanced insulin sensitivity via the PI3K/Akt pathway. Moreover, the combination of XOS and IMO synergistically promoted the oxidation and breakdown of fatty acids and increased the abundance of acetate and propionate-producing bacteria, such as Lactobacillus. These findings suggest a novel strategy for obesity management based on dietary intervention with XOS and IMO.

Effects of Pterostilbene on Cardiovascular Health and Disease

Pterostilbene is a phenolic compound commonly found in blueberries, peanuts, grapes, and other plants. It is a dimethoxy derivative of resveratrol. In recent years, it has gained significant attention due to its remarkable anti-inflammatory and antioxidant effects. In addition, its high bioavailability and low toxicity in many species has contributed to its promising research prospects. Cardiovascular disease is closely related to pathological processes such as inflammation and oxidative stress, which aligns well with the treatment applications of pterostilbene. As a result, numerous studies have investigated the effects of pterostilbene on cardiovascular health and disease. This paper summarizes the current research on pterostilbene, with a specific focus on its potential therapeutic role in treating cardiovascular disease.

Cardiovascular protection of YiyiFuzi powder and the potential mechanisms through modulating mitochondria-endoplasmic reticulum interactions

Cardiovascular diseases (CVD) remain the leading cause of death worldwide and represent a major public health challenge. YiyiFuzi Powder (YYFZ), composed of Coicis semen and Fuzi, is a classical traditional Chinese medicine prescription from the Synopsis of Golden Chamber dating back to the Han Dynasty. Historically, YYFZ has been used to treat various CVD, rooted in Chinese therapeutic principles. Network pharmacology analysis indicated that YYFZ may exhibit direct or indirect effects on mitochondria-endoplasmic reticulum (ER) interactions. This review, focusing on the cardiovascular protective effects of Coicis semen and Fuzi, summarizes the potential mechanisms by which YYFZ acts on mitochondria and the ER. The underlying mechanisms are associated with regulating cardiovascular risk factors (such as blood lipids and glucose), impacting mitochondrial structure and function, modulating ER stress, inhibiting oxidative stress, suppressing inflammatory responses, regulating cellular apoptosis, and maintaining calcium ion balance. The involved pathways include, but were not limited to, upregulating the IGF-1/PI3K/AKT, cAMP/PKA, eNOS/NO/cGMP/SIRT1, SIRT1/PGC-1α, Klotho/SIRT1, OXPHOS/ATP, PPARα/PGC-1α/SIRT3, AMPK/JNK, PTEN/PI3K/AKT, β2-AR/PI3K/AKT, and modified Q cycle signaling pathways. Meanwhile, the MCU, NF-κB, and JAK/STAT signaling pathways were downregulated. The PERK/eIF2α/ATF4/CHOP, PERK/SREBP-1c/FAS, IRE1, PINK1-dependent mitophagy, and AMPK/mTOR signaling pathways were bidirectionally regulated. High-quality experimental studies are needed to further elucidate the underlying mechanisms of YYFZ in CVD treatment.

Maternal Protein Restriction Inhibits Insulin Signaling and Insulin Resistance in the Skeletal Muscle of Young Adult Rats

Objectives

Infants with fetal growth restriction (FGR) are at a risk of developing metabolic syndromes in adulthood. We hypothesized that skeletal muscle degeneration by nutrition-restricted FGR results in abnormal insulin signaling and epigenetic changes.

Material and Methods

To develop a protein-restricted FGR model, rats were fed a low-protein diet (7% protein) during the gestational period; rats fed a normal diet (20% protein) were used as controls. At 8 and 12 weeks of age, the pups were subjected to oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) to evaluate insulin resistance. At 12 weeks, the mRNA and protein levels of insulin signaling pathway molecules in the skeletal muscles were examined. DNA methylation of promoters was detected. DNA extracted from skeletal muscles was used as a template for methylation-specific PCR analysis of GLUT4.

Results

The body weight of FGR rats from birth to 8 weeks was significantly lower than that of the controls; no significant difference was observed between the groups at 12 weeks. In the OGTT and ITT, the incremental area under the curve (iAUC) was significantly higher in FGR rats than in the controls at 12 weeks. The mRNA and protein levels of Akt2 and GLUT4 in the plantar muscles were significantly lower in FGR rats than in the controls. GLUT4 methylation was comparable between the groups.

Conclusions

Protein-restricted FGR rats showed insulin resistance and altered insulin signaling in skeletal muscles after 12 weeks. However, we could not demonstrate the involvement of DNA methylation in this model.

Coconut (Cocos nucifera (L.)) Water Improves Glucose Uptake with Concomitant Modulation of Antioxidant and Purinergic Activities in Isolated Rat Psoas Muscles

The present study investigated the effect of coconut water on glucose uptake and utilization, and metabolic activities linked to hyperglycemia in isolated rat psoas muscles. Coconut water was subjected to in vitro antioxidant and antidiabetic assays, which cover 2,2'-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, ferric reducing antioxidant power (FRAP), and inhibition of α-glucosidase and α-amylase activities. Psoas muscles were isolated from male Sprague Dawley rats and incubated with coconut water in the presence of glucose. Control consisted of muscles incubated with glucose only, while normal control consisted of muscles not incubated in coconut water and/or glucose. The standard antidiabetic drug was metformin. Incubation with coconut water led to a significant increase in muscle glucose uptake, with concomitant exacerbation of glutathione level, and SOD and catalase activities, while suppressing malondialdehyde level, and ATPase and E-NTDase activities. Coconut water showed significant scavenging activity against DPPH, and significantly inhibited α-glucosidase and α-amylase activities. LC-MS analysis of coconut water revealed the presence of ellagic acid, butin, quercetin, protocatechuic acid, baicalin, and silibinin. Molecular docking analysis revealed potent molecular interactions between the LC-MS-identified compounds, and AKT-2 serine and PI-3 kinase. These results indicate the potential of coconut water to enhance glucose uptake, while concomitantly improving antioxidative and purinergic activities. They also indicate the potential of coconut water to suppress postprandial hyperglycemia. These activities may be attributed to the synergistic effects of the LC-MS-identified compounds.

Complex rearrangement in TBC1D4 in an individual with diabetes due to severe insulin resistance syndrome

Severe insulin resistance syndromes result from primary insulin signaling defects, adipose tissue abnormalities or other complex syndromes. Mutations in TBC1D4 lead to partial insulin signaling defects, characterized mainly by postprandial insulin resistance. We describe an individual with severe insulin-resistant diabetes unresponsive to multiple therapies, in whom exome and genome analyses identified a complex rearrangement in TBC1D4. The rearrangement was of the pattern DUP-TRP/INV-DUP, with mutational signatures suggestive of replicative repair and Alu-Alu recombination as the underlying mechanisms. TBC1D4 encodes the TBC1D4/AS160 RabGTPase activating protein (RabGAP) involved in the translocation of glucose transporter 4 (GLUT4) from the cytosol to the cell membrane. Although the precise functional mechanism underlying insulin resistance in the proband is yet to be determined, this case provides further support for the link between TBC1D4 and hereditary insulin-resistant diabetes.

Methylglyoxal Induced Modifications to Stabilize Therapeutic Proteins: A Review

Therapeutic proteins are potent, fast-acting drugs that are highly effective in treating various conditions. Medicinal protein usage has increased in the past 10 years, and it will evolve further as we better understand disease molecular pathways. However, it is associated with high processing costs, limited stability, difficulty in being administered as an oral medication, and the inability of large proteins to penetrate tissue and reach their target locations. Many methods have been developed to overcome the problems with the stability and chaperone activity of therapeutic proteins, viz., the addition of external agents (changing the properties of the surrounding solvent by using stabilizing excipients, e.g., amino acids, sugars, polyols) and internal agents (chemical modifications that influence its structural properties, e.g., mutations, glycosylation). However, these methods must completely clear protein instability and chaperone issues. There is still much work to be done on finetuning chaperone proteins to increase their biological efficacy and stability. Methylglyoxal (MGO), a potent dicarbonyl compound, reacts with proteins and forms covalent cross-links. Much research on MGO scavengers has been conducted since they are known to alter protein structure, which may result in alterations in biological activity and stability. MGO is naturally produced within our body, however, its impact on chaperones and protein stability needs to be better understood and seems to vary based on concentration. This review highlights the efforts of several research groups on the effect of MGO on various proteins. It also addresses the impact of MGO on a client protein, α-crystallin, to understand the potential solutions to the protein's chaperone and stability problems.

The gene expression profile and cell of origin of canine peripheral T-cell lymphoma

BACKGROUND

Peripheral T-cell lymphoma (PTCL) refers to a heterogenous group of T-cell neoplasms with poor treatment responses and survival times. Canine PTCL clinically and immunophenotypically resembles the most common human subtype, PTCL-not otherwise specified (PTCL-NOS), leading to interest in this canine disease as a naturally occurring model for human PTCL. Gene expression profiling in human PTCL-NOS has helped characterize this ambiguous diagnosis into distinct subtypes, but similar gene expression profiling in canine PTCL is lacking.

METHODS

Bulk RNA-sequencing was performed on tumor samples from 33 dogs with either CD4+ (26/33), CD8+ (4/33), or CD4-CD8- (3/33) PTCL as diagnosed by flow cytometry, and sorted CD4+ and CD8+ lymphocytes from healthy control dogs. Following normalization of RNA-seq data, we performed differential gene expression and unsupervised clustering methods. Gene set enrichment analysis was performed to determine the enrichment of canine CD4+ PTCL for human PTCL-NOS, oncogenic pathways, and various stages of T-cell development gene signatures. We utilized gene set variation analysis to evaluate individual canine CD4+ PTCLs for various human and murine T-cell and thymocyte gene signatures. Cultured canine PTCL cells were treated with a pan-PI3K inhibitor, and cell survival and proliferation were compared to DMSO-treated controls. Expression of GATA3 and phosphorylated AKT was validated by immunohistochemistry.

RESULTS

While the canine CD4+ PTCL phenotype exhibited a consistent gene expression profile, the expression profiles of CD8+ and CD4-CD8- canine PTCLs were more heterogeneous. Canine CD4+ PTCL had increased expression of GATA3, upregulation of its target genes, enrichment for PI3K/AKT/mTOR signaling, and downregulation of PTEN, features consistent with the more aggressive GATA3-PTCL subtype of human PTCL-NOS. In vitro assays validated the reliance of canine CD4+ PTCL cells on PI3K/AKT/mTOR signaling for survival and proliferation. Canine CD4+ PTCL was enriched for thymic precursor gene signatures, exhibited increased expression of markers of immaturity (CD34, KIT, DNTT, and CCR9), and downregulated genes associated with the T-cell receptor, MHC class II associated genes (DLA-DQA1, DLA-DRA, HLA-DQB1, and HLA-DQB2), and CD25.

CONCLUSIONS

Canine CD4+ PTCL most closely resembled the GATA3-PTCL subtype of PTCL-NOS and may originate from an earlier stage of T-cell development than the more conventionally posited mature T-helper cell origin.

The pharmacological effects of Berberine and its therapeutic potential in different diseases: Role of the phosphatidylinositol 3-kinase/AKT signaling pathway

The phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway plays a central role in cell growth and survival and is disturbed in various pathologies. The PI3K is a kinase that generates phosphatidylinositol-3,4,5-trisphosphate (PI (3-5) P3), as a second messenger responsible for the translocation of AKT to the plasma membrane and its activation. However, due to the crucial role of the PI3K/AKT pathway in regulation of cell survival processes, it has been introduced as a main therapeutic target for natural compounds during the progression of different pathologies. Berberine, a plant-derived isoquinone alkaloid, is known because of its anti-inflammatory, antioxidant, antidiabetic, and antitumor properties. The effect of this natural compound on cell survival processes has been shown to be mediated by modulation of the intracellular pathways. However, the effects of this natural compound on the PI3K/AKT pathway in various pathologies have not been reviewed so far. Therefore, this paper aims to review the PI3K/AKT-mediated effects of Berberine in different types of cancer, diabetes, cardiovascular, and central nervous system diseases.

Control of gastruloid patterning and morphogenesis by the Erk and Akt signaling pathways

Many developmental processes rely on the localized activation of receptor tyrosine kinases and their canonical downstream effectors Erk and Akt, yet the specific roles played by each of these signals is still poorly understood. Gastruloids, 3D cell culture models of mammalian gastrulation and axial elongation, enable quantitative dissection of signaling patterns and cell responses in a simplified, experimentally accessible context. We find that mouse gastruloids contain posterior-to-anterior gradients of Erk and Akt phosphorylation induced by distinct receptor tyrosine kinases, with features of the Erk pattern and expression of its downstream target Snail exhibiting hallmarks of size-invariant scaling. Both Erk and Akt signaling contribute to cell proliferation, whereas Erk activation is also sufficient to induce Snail expression and precipitate profound tissue shape changes. We further uncover that Erk signaling is sufficient to convert the entire gastruloid to one of two mesodermal fates depending on position along the anteroposterior axis. In all, these data demonstrate functional roles for two core signaling gradients in mammalian development and suggest how these modules might be harnessed to engineer user-defined tissues with predictable shapes and cell fates.

Energy stress-induced circZFR enhances oxidative phosphorylation in lung adenocarcinoma via regulating alternative splicing

BACKGROUND

Circular RNAs (circRNAs) contribute to multiple biological functions and are also involved in pathological conditions such as cancer. However, the role of circRNAs in metabolic reprogramming, especially upon energy stress in lung adenocarcinoma (LUAD), remains largely unknown.

METHODS

Energy stress-induced circRNA was screened by circRNA profiling and glucose deprivation assays. RNA-seq, real-time cell analyzer system (RTCA) and measurement of oxygen consumption rate (OCR) were performed to explore the biological functions of circZFR in LUAD. The underlying mechanisms were investigated using circRNA pull-down, RNA immunoprecipitation, immunoprecipitation and bioinformatics analysis of alternative splicing. Clinical implications of circZFR were assessed in 92 pairs of LUAD tissues and adjacent non-tumor tissues, validated in established patient-derived tumor xenograft (PDTX) model.

RESULTS

CircZFR is induced by glucose deprivation and is significantly upregulated in LUAD compared to adjacent non-tumor tissues, enhancing oxidative phosphorylation (OXPHOS) for adaptation to energy stress. CircZFR is strongly associated with higher T stage and poor prognosis in patients with LUAD. Mechanistically, circZFR protects heterogeneous nuclear ribonucleoprotein L-like (HNRNPLL) from degradation by ubiquitination to regulate alternative splicing, such as myosin IB (MYO1B), and subsequently activates the AKT-mTOR pathway to facilitate OXPHOS.

CONCLUSION

Our study provides new insights into the role of circRNAs in anticancer metabolic therapies and expands our understanding of alternative splicing.

Signaling pathways and intervention for therapy of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) represents one of the fastest growing epidemic metabolic disorders worldwide and is a strong contributor for a broad range of comorbidities, including vascular, visual, neurological, kidney, and liver diseases. Moreover, recent data suggest a mutual interplay between T2DM and Corona Virus Disease 2019 (COVID-19). T2DM is characterized by insulin resistance (IR) and pancreatic β cell dysfunction. Pioneering discoveries throughout the past few decades have established notable links between signaling pathways and T2DM pathogenesis and therapy. Importantly, a number of signaling pathways substantially control the advancement of core pathological changes in T2DM, including IR and β cell dysfunction, as well as additional pathogenic disturbances. Accordingly, an improved understanding of these signaling pathways sheds light on tractable targets and strategies for developing and repurposing critical therapies to treat T2DM and its complications. In this review, we provide a brief overview of the history of T2DM and signaling pathways, and offer a systematic update on the role and mechanism of key signaling pathways underlying the onset, development, and progression of T2DM. In this content, we also summarize current therapeutic drugs/agents associated with signaling pathways for the treatment of T2DM and its complications, and discuss some implications and directions to the future of this field.

Genome-wide association study and functional characterization identifies candidate genes for insulin-stimulated glucose uptake

Distinct tissue-specific mechanisms mediate insulin action in fasting and postprandial states. Previous genetic studies have largely focused on insulin resistance in the fasting state, where hepatic insulin action dominates. Here we studied genetic variants influencing insulin levels measured 2 h after a glucose challenge in >55,000 participants from three ancestry groups. We identified ten new loci (P < 5 × 10-8) not previously associated with postchallenge insulin resistance, eight of which were shown to share their genetic architecture with type 2 diabetes in colocalization analyses. We investigated candidate genes at a subset of associated loci in cultured cells and identified nine candidate genes newly implicated in the expression or trafficking of GLUT4, the key glucose transporter in postprandial glucose uptake in muscle and fat. By focusing on postprandial insulin resistance, we highlighted the mechanisms of action at type 2 diabetes loci that are not adequately captured by studies of fasting glycemic traits.

Uses of Papaya Leaf and Seaweed Supplementations for Controlling Glucose Homeostasis in Diabetes

Studies from laboratory animal models and complementary medical practices have implied that nutrients from special plants or herbs contain antidiabetic, antioxidant, anti-obese, anti-hypertensive, and anti-inflammatory properties. Seaweed and tropical papaya, which are widely available in Asian and Pacific countries, have been used as home remedies for centuries. The bioactive extracts from these plants contain vitamins A, C, B and E complexes, as well as polysaccharides, phenolic compounds, essential fatty acids, flavonoids, saponins, fucoidan, and phlorotannin. In this review, the authors examine the pathogenesis of diabetes characterized by hyperglycemia due to the dysregulation of glucose homeostasis, antidiabetic/antihyperglycemic seaweed or/and papaya derived bioactive phytochemicals and their proposed mechanisms of action in the management of Type 2 Diabetes Mellitus (T2DM). The authors also propose combining papaya and seaweed to enhance their antidiabetic effects, leveraging the advantages of herb-to-herb combination. Papaya and seaweed have demonstrated antidiabetic effects through in vitro assays, cellular models, and animal studies despite the limited clinical trials. Nutraceuticals with antidiabetic effects, such as secondary metabolites isolated from seaweed and papaya, could be combined for a synergistic effect on T2DM management. However, the application of these compounds in their purified or mixed forms require further scientific studies to evaluate their efficacy against diabetes-related complications, such as hyperlipidemia, elevated free radicals, pro-inflammatory molecules, insulin insensitivity, and the degeneration of pancreatic beta cells.

Optogenetic decoding of Akt2-regulated metabolic signaling pathways in skeletal muscle cells using transomics analysis

Insulin regulates various cellular metabolic processes by activating specific isoforms of the Akt family of kinases. Here, we elucidated metabolic pathways that are regulated in an Akt2-dependent manner. We constructed a transomics network by quantifying phosphorylated Akt substrates, metabolites, and transcripts in C2C12 skeletal muscle cells with acute, optogenetically induced activation of Akt2. We found that Akt2-specific activation predominantly affected Akt substrate phosphorylation and metabolite regulation rather than transcript regulation. The transomics network revealed that Akt2 regulated the lower glycolysis pathway and nucleotide metabolism and cooperated with Akt2-independent signaling to promote the rate-limiting steps in these processes, such as the first step of glycolysis, glucose uptake, and the activation of the pyrimidine metabolic enzyme CAD. Together, our findings reveal the mechanism of Akt2-dependent metabolic pathway regulation, paving the way for Akt2-targeting therapeutics in diabetes and metabolic disorders.

Redox integration of signaling and metabolism in a head and neck cancer model of radiation resistance using COSMRO

Redox metabolism is increasingly investigated in cancer as driving regulator of tumor progression, response to therapies and long-term patients' quality of life. Well-established cancer therapies, such as radiotherapy, either directly impact redox metabolism or have redox-dependent mechanisms of action defining their clinical efficacy. However, the ability to integrate redox information across signaling and metabolic networks to facilitate discovery and broader investigation of redox-regulated pathways in cancer remains a key unmet need limiting the advancement of new cancer therapies. To overcome this challenge, we developed a new constraint-based computational method (COSMro) and applied it to a Head and Neck Squamous Cell Cancer (HNSCC) model of radiation resistance. This novel integrative approach identified enhanced capacity for H2S production in radiation resistant cells and extracted a key relationship between intracellular redox state and cholesterol metabolism; experimental validation of this relationship highlights the importance of redox state in cellular metabolism and response to radiation.

Methylglyoxal and Its Adducts: Induction, Repair, and Association with Disease

Metabolism is an essential part of life that provides energy for cell growth. During metabolic flux, reactive electrophiles are produced that covalently modify macromolecules, leading to detrimental cellular effects. Methylglyoxal (MG) is an abundant electrophile formed from lipid, protein, and glucose metabolism at intracellular levels of 1-4 μM. MG covalently modifies DNA, RNA, and protein, forming advanced glycation end products (MG-AGEs). MG and MG-AGEs are associated with the onset and progression of many pathologies including diabetes, cancer, and liver and kidney disease. Regulating MG and MG-AGEs is a potential strategy to prevent disease, and they may also have utility as biomarkers to predict disease risk, onset, and progression. Here, we review recent advances and knowledge surrounding MG, including its production and elimination, mechanisms of MG-AGEs formation, the physiological impact of MG and MG-AGEs in disease onset and progression, and the latter in the context of its receptor RAGE. We also discuss methods for measuring MG and MG-AGEs and their clinical application as prognostic biomarkers to allow for early detection and intervention prior to disease onset. Finally, we consider relevant clinical applications and current therapeutic strategies aimed at targeting MG, MG-AGEs, and RAGE to ultimately improve patient outcomes.

RING-finger E3 ligases regulatory network in PI3K/AKT-mediated glucose metabolism

The phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway plays an essential role in glucose metabolism, promoting glycolysis and resisting gluconeogenesis. PI3K/AKT signaling can directly alter glucose metabolism by phosphorylating several metabolic enzymes or regulators of nutrient transport. It can indirectly promote sustained aerobic glycolysis by increasing glucose transporters and glycolytic enzymes, which are mediated by downstream transcription factors. E3 ubiquitin ligase RING-finger proteins are mediators of protein post-translational modifications and include the cullin-RING ligase complexes, the tumor necrosis factor receptor-associated family, the tripartite motif family and etc. Some members of the RING family play critical roles in regulating cell signaling and are involved in the development and progression of various metabolic diseases, such as cancer, diabetes, and dyslipidemia. And with the progression of modern research, as a negative or active regulator, the RING-finger adaptor has been found to play an indispensable role in PI3K/AKT signaling. However, no reviews have comprehensively clarified the role of RING-finger E3 ligases in PI3K/AKT-mediated glucose metabolism. Therefore, in this review, we focus on the regulation and function of RING ligases in PI3K/AKT-mediated glucose metabolism to establish new insights into the prevention and treatment of metabolic diseases.

Trafficking regulator of GLUT4-1 (TRARG1) is a GSK3 substrate

Trafficking regulator of GLUT4-1, TRARG1, positively regulates insulin-stimulated GLUT4 trafficking and insulin sensitivity. However, the mechanism(s) by which this occurs remain(s) unclear. Using biochemical and mass spectrometry analyses we found that TRARG1 is dephosphorylated in response to insulin in a PI3K/Akt-dependent manner and is a novel substrate for GSK3. Priming phosphorylation of murine TRARG1 at serine 84 allows for GSK3-directed phosphorylation at serines 72, 76 and 80. A similar pattern of phosphorylation was observed in human TRARG1, suggesting that our findings are translatable to human TRARG1. Pharmacological inhibition of GSK3 increased cell surface GLUT4 in cells stimulated with a submaximal insulin dose, and this was impaired following Trarg1 knockdown, suggesting that TRARG1 acts as a GSK3-mediated regulator in GLUT4 trafficking. These data place TRARG1 within the insulin signaling network and provide insights into how GSK3 regulates GLUT4 trafficking in adipocytes.

GLUT4 On the move

Insulin rapidly stimulates GLUT4 translocation and glucose transport in fat and muscle cells. Signals from the occupied insulin receptor are translated into downstream signalling changes in serine/threonine kinases within timescales of seconds, and this is followed by delivery and accumulation of the glucose transporter GLUT4 at the plasma membrane. Kinetic studies have led to realisation that there are distinct phases of this stimulation by insulin. There is a rapid initial burst of GLUT4 delivered to the cell surface from a subcellular reservoir compartment and this is followed by a steady-state level of continuing stimulation in which GLUT4 recycles through a large itinerary of subcellular locations. Here, we provide an overview of the phases of insulin stimulation of GLUT4 translocation and the molecules that are currently considered to activate these trafficking steps. Furthermore, we suggest how use of new experimental approaches together with phospho-proteomic data may help to further identify mechanisms for activation of these trafficking processes.

The role of mitochondrial reactive oxygen species in insulin resistance

Insulin resistance is one of the earliest pathological features of a suite of diseases including type 2 diabetes collectively referred to as metabolic syndrome. There is a growing body of evidence from both pre-clinical studies and human cohorts indicating that reactive oxygen species, such as the superoxide radical anion and hydrogen peroxide are key players in the development of insulin resistance. Here we review the evidence linking mitochondrial reactive oxygen species generated within mitochondria with insulin resistance in adipose tissue and skeletal muscle, two major insulin sensitive tissues. We outline the relevant mitochondria-derived reactive species, how the mitochondrial redox state is regulated, and methodologies available to measure mitochondrial reactive oxygen species. Importantly, we highlight key experimental issues to be considered when studying the role of mitochondrial reactive oxygen species in insulin resistance. Evaluating the available literature on both mitochondrial reactive oxygen species/redox state and insulin resistance in a variety of biological systems, we conclude that the weight of evidence suggests a likely role for mitochondrial reactive oxygen species in the etiology of insulin resistance in adipose tissue and skeletal muscle. However, major limitations in the methods used to study reactive oxygen species in insulin resistance as well as the lack of data linking mitochondrial reactive oxygen species and cytosolic insulin signaling pathways are significant obstacles in proving the mechanistic link between these two processes. We provide a framework to guide future studies to provide stronger mechanistic information on the link between mitochondrial reactive oxygen species and insulin resistance as understanding the source, localization, nature, and quantity of mitochondrial reactive oxygen species, their targets and downstream signaling pathways may pave the way for important new therapeutic strategies.

Ubiquitin-like processing of TUG proteins as a mechanism to regulate glucose uptake and energy metabolism in fat and muscle

In response to insulin stimulation, fat and muscle cells mobilize GLUT4 glucose transporters to the cell surface to enhance glucose uptake. Ubiquitin-like processing of TUG (Aspscr1, UBXD9) proteins is a central mechanism to regulate this process. Here, recent advances in this area are reviewed. The data support a model in which intact TUG traps insulin-responsive "GLUT4 storage vesicles" at the Golgi matrix by binding vesicle cargoes with its N-terminus and matrix proteins with its C-terminus. Insulin stimulation liberates these vesicles by triggering endoproteolytic cleavage of TUG, mediated by the Usp25m protease. Cleavage occurs in fat and muscle cells, but not in fibroblasts or other cell types. Proteolytic processing of intact TUG generates TUGUL, a ubiquitin-like protein modifier, as the N-terminal cleavage product. In adipocytes, TUGUL modifies a single protein, the KIF5B kinesin motor, which carries GLUT4 and other vesicle cargoes to the cell surface. In muscle, this or another motor may be modified. After cleavage of intact TUG, the TUG C-terminal product is extracted from the Golgi matrix by the p97 (VCP) ATPase. In both muscle and fat, this cleavage product enters the nucleus, binds PPARγ and PGC-1α, and regulates gene expression to promote fatty acid oxidation and thermogenesis. The stability of the TUG C-terminal product is regulated by an Ate1 arginyltransferase-dependent N-degron pathway, which may create a feedback mechanism to control oxidative metabolism. Although it is now clear that TUG processing coordinates glucose uptake with other aspects of physiology and metabolism, many questions remain about how this pathway is regulated and how it is altered in metabolic disease in humans.

Optical Control of Phosphoinositide Binding: Rapid Activation of Subcellular Protein Translocation and Cell Signaling

Cells utilize protein translocation to specific compartments for spatial and temporal regulation of protein activity, in particular in the context of signaling processes. Protein recognition and binding to various subcellular membranes is mediated by a network of phosphatidylinositol phosphate (PIP) species bearing one or multiple phosphate moieties on the polar inositol head. Here, we report a new, highly efficient method for optical control of protein localization through the site-specific incorporation of a photocaged amino acid for steric and electrostatic disruption of inositol phosphate recognition and binding. We demonstrate general applicability of the approach by photocaging two unrelated proteins, sorting nexin 3 (SNX3) and the pleckstrin homology (PH) domain of phospholipase C delta 1 (PLCδ1), with two distinct PIP binding domains and distinct subcellular localizations. We have established the applicability of this methodology through its application to Son of Sevenless 2 (SOS2), a signaling protein involved in the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) cascade. Upon fusing the photocaged plasma membrane-targeted construct PH-enhanced green fluorescent protein (EGFP), to the catalytic domain of SOS2, we demonstrated light-induced membrane localization of the construct resulting in fast and extensive activation of the ERK signaling pathway in NIH 3T3 cells. This approach can be readily extended to other proteins, with minimal protein engineering, and provides a method for acute optical control of protein translocation with rapid and complete activation.

Omega-3 polyunsaturated fatty acids promote SNAREs mediated GLUT4 vesicle docking and fusion

Glucose homeostasis imbalance and insulin resistance (IR) are major contributors to the incidence of type 2 diabetes. Omega-3 polyunsaturated fatty acids (PUFAs) are key ingredients for maintaining cellular functions and improving insulin sensitivity. However, how omega-3 PUFAs modulate the dynamic process of glucose transport at the cellular level remains unclear. Here we unraveled eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may regulate the glucose transporter 4 (GLUT4) vesicle trafficking in both normal and IR adipocytes. Both omega-3 PUFAs significantly increase glucose consumption within a range of 10-32% in the basal state. Furthermore, both EPA (200 μM) and DHA (100 μM) may significantly promote the serine/threonine protein kinase (Akt) phosphorylation by 70% and 40% in the physiological state of adipocytes, respectively. Both omega-3 PUFAs significantly advanced the Akt phosphorylation in a dose-dependent way and showed a ∼2-fold increase at the dose of 200 μM in the IR pathological state. However, they could not up-regulate the expression of GLUT4 and insulin-regulated aminopeptidase protein. We further revealed that both omega-3 PUFAs dynamically promote insulin-stimulated GLUT4 vesicle translocation and soluble N-ethylmaleimide-sensitive factor attachment protein receptor mediated vesicle docking and fusion to the plasma membrane via specifically modulating the expression of vesicle-associated membrane protein 2. Understanding the mechanisms by which omega-3 PUFAs modulate cellular metabolism and IR in peripheral tissues may provide novel insights into the potential impact of omega-3 PUFAs on the metabolic function and the management of IR.

Fission Yeast TORC2 Signaling Pathway Ensures Cell Proliferation under Glucose-Limited, Nitrogen-Replete Conditions

Target of rapamycin (TOR) kinases form two distinct complexes, TORC1 and TORC2, which are evolutionarily conserved among eukaryotes. These complexes control intracellular biochemical processes in response to changes in extracellular nutrient conditions. Previous studies using the fission yeast, Schizosaccharomyces pombe, showed that the TORC2 signaling pathway, which is essential for cell proliferation under glucose-limited conditions, ensures cell-surface localization of a high-affinity hexose transporter, Ght5, by downregulating its endocytosis. The TORC2 signaling pathway retains Ght5 on the cell surface, depending on the presence of nitrogen sources in medium. Ght5 is transported to vacuoles upon nitrogen starvation. In this review, we discuss the molecular mechanisms underlying this regulation to cope with nutritional stress, a response which may be conserved from yeasts to mammals.

Trimetazidine Attenuates Heart Failure by Improving Myocardial Metabolism via AMPK

Energic deficiency of cardiomyocytes is a dominant cause of heart failure. An antianginal agent, trimetazidine improves the myocardial energetic supply. We presumed that trimetazidine protects the cardiomyocytes from the pressure overload-induced heart failure through improving the myocardial metabolism. C57BL/6 mice were subjected to transverse aortic constriction (TAC). After 4 weeks of TAC, heart failure was observed in mice manifested by an increased left ventricular (LV) chamber dimension, an impaired LV ejection fraction evaluated by echocardiography analysis, which were significantly restrained by the treatment of trimetazidine. Trimetazidine restored the mitochondrial morphology and function tested by cardiac transmission electron microscope and mitochondrial dynamic proteins analysis. Positron emission tomography showed that trimetazidine significantly elevated the glucose uptake in TAC mouse heart. Trimetazidine restrained the impairments of the insulin signaling in TAC mice and promoted the translocation of glucose transporter type IV (GLUT4) from the storage vesicle to membrane. However, these cardioprotective effects of trimetazidine in TAC mice were notably abolished by compound C (C.C), a specific AMPK inhibitor. The enlargement of neonatal rat cardiomyocyte induced by mechanical stretch, together with the increased expression of hypertrophy-associated proteins, mitochondria deformation and dysfunction were significantly ameliorated by trimetazidine. Trimetazidine enhanced the isolated cardiomyocyte glucose uptake in vitro. These benefits brought by trimetazidine were also removed with the presence of C.C. In conclusion, trimetazidine attenuated pressure overload-induced heart failure through improving myocardial mitochondrial function and glucose uptake via AMPK.

Quantitative comparative phosphoproteomic analysis of the effects of colostrum and milk feeding on liver tissue of neonatal calves

Posttranslational modifications, mostly phosphorylation, are critical for protein structure and function. However, the association between liver phosphoproteins in neonatal calves and colostrum intake is not well understood. In this study, we examined the liver phosphoproteome profile in neonatal calves after receiving colostrum or milk. Liver tissue samples were collected from control calves (CON, n = 3) 2 h after birth and from calves that received colostrum (CG, n = 3) or milk (MG, n = 3) 24 h after birth. Hepatic phosphoprotein expression profiles were analyzed using quantitative proteomics based on the liquid chromatography-tandem mass spectrometry method. In total, 1,587 phosphorylated sites were identified in 1,011 liver proteins. The most abundant phosphorylation site AA was serine (87.5%), followed by threonine (11.9%) and tyrosine (0.5%). Among the 1,011 phosphoproteins, 219, 453, and 26 displayed differential expression in the CG versus MG, CG versus CON, and MG versus CON comparisons, respectively. Differentially expressed phosphoproteins in the CG-MG comparison included 3-phosphoinositide-dependent protein kinase 1, glucose transporter member 4, protein kinase N2, and vinculin, which were mainly involved in the glycogen metabolic process, transport, growth and development, and cell adhesion process, according to Gene Ontology analysis. Pathway analysis indicated their enrichment in the insulin signaling pathway, spliceosome, and adherens junction. The CG-CON comparison identified differentially expressed phosphoproteins and their target genes that were largely involved in the cellular process, macromolecule metabolic process, developmental process, and transport. Pathway analysis indicated their association with endocytosis, mechanistic target of rapamycin, AMP-activated protein kinase, and insulin signaling pathways. These data demonstrate that changes in the phosphoproteins of liver tissues may play an important role in energy metabolism and immune response in the calves that received colostrum. These results provide novel insights into the crucial roles of protein phosphorylation during the early life of newborn calves.

Comparative Transcriptome Analysis of Key Genes and Pathways Activated in Response to Fat Deposition in Two Sheep Breeds With Distinct Tail Phenotype

Fat tail in sheep presents a valuable energy reserve that has historically facilitated adaptation to harsh environments. However, in modern intensive and semi-intensive sheep industry systems, breeds with leaner tails are more desirable. In the present study, RNA sequencing (RNA-Seq) was applied to determine the transcriptome profiles of tail fat tissues in two Chinese sheep breeds, fat-rumped Altay sheep and thin-tailed Xinjiang fine wool (XFW) sheep, with extreme fat tail phenotype difference. Then the differentially expressed genes (DEGs) and their sequence variations were further analyzed. In total, 21,527 genes were detected, among which 3,965 displayed significant expression variations in tail fat tissues of the two sheep breeds (P < 0.05), including 707 upregulated and 3,258 downregulated genes. Gene Ontology (GO) analysis disclosed that 198 DEGs were related to fat metabolism. In Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, the majority of DEGs were significantly enriched in "adipocytokine signaling," "PPAR signaling," and "metabolic pathways" (P < 0.05); moreover, some genes were involved in multiple pathways. Among the 198 DEGs, 22 genes were markedly up- or downregulated in tail fat tissue of Altay sheep, indicating that these genes might be closely related to the fat tail trait of this breed. A total of 41,724 and 42,193 SNPs were detected in the transcriptomic data of tail fat tissues obtained from Altay and XFW sheep, respectively. The distribution of seven SNPs in the coding regions of the 22 candidate genes was further investigated in populations of three sheep breeds with distinct tail phenotypes. In particular, the g.18167532T/C (Oar_v3.1) mutation of the ATP-binding cassette transporter A1 (ABCA1) gene and g.57036072G/T (Oar_v3.1) mutation of the solute carrier family 27 member 2 (SLC27A2) gene showed significantly different distributions and were closely associated with tail phenotype (P < 0.05). The present study provides transcriptomic evidence explaining the differences in fat- and thin-tailed sheep breeds and reveals numerous DEGs and SNPs associated with tail phenotype. Our data provide a valuable theoretical basis for selection of lean-tailed sheep breeds.

Gamma-aminobutyric acid attenuates insulin resistance in type 2 diabetic patients and reduces the risk of insulin resistance in their offspring

The role of gamma-aminobutyric acid (GABA) in attenuates insulin resistance (IR) in type 2 diabetic (T2D) patients and the reduction of the risk of IR in their offspring, and the function of GLUT4, IRS1 and Akt2 genes expression were investigated. T2D was induced by high fat diet and 35 mg/kg of streptozotocin. The male and female diabetic rats were then divided into three groups: CD, GABA, and insulin. NDC group received a normal diet. All the animals were studied for a six-month. Their offspring were just fed with normal diet for four months. Blood glucose was measured weekly in patients and their offspring. Intraperitoneal glucose tolerance test (IPGTT), urine volume, and water consumption in both patients and their offspring were performed monthly. The hyperinsulinemic euglycemic clamp in both patients and their offspring was done and blood sample collected to measure Hemoglobin A1c (HbA1c). IRS1, Akt and GLUT4 gene expressions in muscle were evaluated in all the groups. GABA or insulin therapy decreased blood glucose, IPGTT, and HbA1c in patients and their offspring compared to DC group. They also increased GIR in patients and their offspring. IRS1, Akt and GLUT4 gene expressions improved in both patients in comparison with DC group. GABA exerts beneficial effects on IRS1 and Akt gene expressions in GABA treated offspring. GABA therapy improved insulin resistance in diabetic patients by increasing the expression of GLUT4. It is also indirectly able to reduce insulin resistance in their offspring possibly through the increased gene expressions of IRS1 and Akt.

Signaling Heterogeneity is Defined by Pathway Architecture and Intercellular Variability in Protein Expression

Insulin's activation of PI3K/Akt signaling, stimulates glucose uptake by enhancing delivery of GLUT4 to the cell surface. Here we examined the origins of intercellular heterogeneity in insulin signaling. Akt activation alone accounted for ~25% of the variance in GLUT4, indicating that additional sources of variance exist. The Akt and GLUT4 responses were highly reproducible within the same cell, suggesting the variance is between cells (extrinsic) and not within cells (intrinsic). Generalized mechanistic models (supported by experimental observations) demonstrated that the correlation between the steady-state levels of two measured signaling processes decreases with increasing distance from each other and that intercellular variation in protein expression (as an example of extrinsic variance) is sufficient to account for the variance in and between Akt and GLUT4. Thus, the response of a population to insulin signaling is underpinned by considerable single-cell heterogeneity that is largely driven by variance in gene/protein expression between cells.

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Insulin signaling is heterogeneous between cells in the same population

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The temporal response of signaling components within a cell is highly reproducible

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Upstream responses (Akt) can only partially predict downstream response (GLUT4)

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Protein expression variance is a driver of intercellular signaling heterogeneity

Integrin and autocrine IGF2 pathways control fasting insulin secretion in β-cells

Elevated levels of fasting insulin release and insufficient glucose-stimulated insulin secretion (GSIS) are hallmarks of diabetes. Studies have established cross-talk between integrin signaling and insulin activity, but more details of how integrin-dependent signaling impacts the pathophysiology of diabetes are needed. Here, we dissected integrin-dependent signaling pathways involved in the regulation of insulin secretion in β-cells and studied their link to the still debated autocrine regulation of insulin secretion by insulin/insulin-like growth factor (IGF) 2-AKT signaling. We observed for the first time a cooperation between different AKT isoforms and focal adhesion kinase (FAK)-dependent adhesion signaling, which either controlled GSIS or prevented insulin secretion under fasting conditions. Indeed, β-cells form integrin-containing adhesions, which provide anchorage to the pancreatic extracellular matrix and are the origin of intracellular signaling via FAK and paxillin. Under low-glucose conditions, β-cells adopt a starved adhesion phenotype consisting of actin stress fibers and large peripheral focal adhesion. In contrast, glucose stimulation induces cell spreading, actin remodeling, and point-like adhesions that contain phospho-FAK and phosphopaxillin, located in small protrusions. Rat primary β-cells and mouse insulinomas showed an adhesion remodeling during GSIS resulting from autocrine insulin/IGF2 and AKT1 signaling. However, under starving conditions, the maintenance of stress fibers and the large adhesion phenotype required autocrine IGF2-IGF1 receptor signaling mediated by AKT2 and elevated FAK-kinase activity and ROCK-RhoA levels but low levels of paxillin phosphorylation. This starved adhesion phenotype prevented excessive insulin granule release to maintain low insulin secretion during fasting. Thus, deregulation of the IGF2 and adhesion-mediated signaling may explain dysfunctions observed in diabetes.

Cancer cell metabolism: Rewiring the mitochondrial hub

To adapt to tumoral environment conditions or even to escape chemotherapy, cells rapidly reprogram their metabolism to handle adversities and survive. Given the rapid rise of studies uncovering novel insights and therapeutic opportunities based on the role of mitochondria in tumor metabolic programing and therapeutics, this review summarizes most significant developments in the field. Taking in mind the key role of mitochondria on carcinogenesis and tumor progression due to their involvement on tumor plasticity, metabolic remodeling, and signaling re-wiring, those organelles are also potential therapeutic targets. Among other topics, we address the recent data intersecting mitochondria as of prognostic value and staging in cancer, by mitochondrial DNA (mtDNA) determination, and current inhibitors developments targeting mtDNA, OXPHOS machinery and metabolic pathways. We contribute for a holistic view of the role of mitochondria metabolism and directed therapeutics to understand tumor metabolism, to circumvent therapy resistance, and to control tumor development.

Insulin: Trigger and Target of Renal Functions

Kidney function in metabolism is often underestimated. Although the word “clearance” is associated to “degradation”, at nephron level, proper balance between what is truly degraded and what is redirected to de novo utilization is crucial for the maintenance of electrolytic and acid–basic balance and energy conservation. Insulin is probably one of the best examples of how diverse and heterogeneous kidney response can be. Kidney has a primary role in the degradation of insulin released in the bloodstream, but it is also incredibly susceptible to insulin action throughout the nephron. Fluctuations in insulin levels during fast and fed state add another layer of complexity in the understanding of kidney fine-tuning. This review aims at revisiting renal insulin actions and clearance and to address the association of kidney dysmetabolism with hyperinsulinemia and insulin resistance, both highly prevalent phenomena in modern society.

From insulin to Akt: Time delays and dominant processes

Akt/PKB regulates numerous processes in the mammalian cell, including cell survival and proliferation, and glucose uptake in response to insulin. Abnormalities in Akt signalling are linked to the development of Type 2 diabetes, cardio-vascular disease, and cancer. In the absence of insulin, Akt is predominantly found in the inactive state in the cytosol. Following insulin stimulation, Akt translocates to the plasma membrane, docks, and is phosphorylated to take on the active conformation. In turn, the activated Akt travels to and phosphorylates its many downstream substrates. Although crucial to the activation process, the translocation of Akt from the cytosol to the plasma membrane is currently not well understood. Here we detail the parameter optimisation of a mathematical model of Akt translocation to experimental data. We have quantified the time delay between the application of insulin and the downstream Akt translocation response, indicating the constraints on the timing of the intermediate processes. A delay of approximately 0.4 min prior to the Akt response was determined for the application of 1 nM insulin to cells in the basal state, whereas it was found that a further transition from physiological insulin to higher stimuli did not incur a delay. Furthermore, our investigation indicates that the dominant processes regulating the appearance of Akt at the plasma membrane differ with the insulin level. For physiological insulin, the rate limiting step was the release of Akt to the plasma membrane in response to the insulin signal. In contrast, at high insulin levels, regulation of the recycling of Akt from the plasma membrane to the cytosol was also required.

Is Mitochondrial Dysfunction a Common Root of Noncommunicable Chronic Diseases?

Mitochondrial damage is implicated as a major contributing factor for a number of noncommunicable chronic diseases such as cardiovascular diseases, cancer, obesity, and insulin resistance/type 2 diabetes. Here, we discuss the role of mitochondria in maintaining cellular and whole-organism homeostasis, the mechanisms that promote mitochondrial dysfunction, and the role of this phenomenon in noncommunicable chronic diseases. We also review the state of the art regarding the preclinical evidence associated with the regulation of mitochondrial function and the development of current mitochondria-targeted therapeutics to treat noncommunicable chronic diseases. Finally, we give an integrated vision of how mitochondrial damage is implicated in these metabolic diseases.

The Implications for Cells of the Lipid Switches Driven by Protein-Membrane Interactions and the Development of Membrane Lipid Therapy

The cell membrane contains a variety of receptors that interact with signaling molecules. However, agonist-receptor interactions not always activate a signaling cascade. Amphitropic membrane proteins are required for signal propagation upon ligand-induced receptor activation. These proteins localize to the plasma membrane or internal compartments; however, they are only activated by ligand-receptor complexes when both come into physical contact in membranes. These interactions enable signal propagation. Thus, signals may not propagate into the cell if peripheral proteins do not co-localize with receptors even in the presence of messengers. As the translocation of an amphitropic protein greatly depends on the membrane's lipid composition, regulation of the lipid bilayer emerges as a novel therapeutic strategy. Some of the signals controlled by proteins non-permanently bound to membranes produce dramatic changes in the cell's physiology. Indeed, changes in membrane lipids induce translocation of dozens of peripheral signaling proteins from or to the plasma membrane, which controls how cells behave. We called these changes "lipid switches", as they alter the cell's status (e.g., proliferation, differentiation, death, etc.) in response to the modulation of membrane lipids. Indeed, this discovery enables therapeutic interventions that modify the bilayer's lipids, an approach known as membrane-lipid therapy (MLT) or melitherapy.

The PI3K-AKT network at the interface of oncogenic signalling and cancer metabolism

The altered metabolic programme of cancer cells facilitates their cell-autonomous proliferation and survival. In normal cells, signal transduction pathways control core cellular functions, including metabolism, to couple the signals from exogenous growth factors, cytokines or hormones to adaptive changes in cell physiology. The ubiquitous, growth factor-regulated phosphoinositide 3-kinase (PI3K)-AKT signalling network has diverse downstream effects on cellular metabolism, through either direct regulation of nutrient transporters and metabolic enzymes or the control of transcription factors that regulate the expression of key components of metabolic pathways. Aberrant activation of this signalling network is one of the most frequent events in human cancer and serves to disconnect the control of cell growth, survival and metabolism from exogenous growth stimuli. Here we discuss our current understanding of the molecular events controlling cellular metabolism downstream of PI3K and AKT and of how these events couple two major hallmarks of cancer: growth factor independence through oncogenic signalling and metabolic reprogramming to support cell survival and proliferation.

Wogonin Alleviates Hyperglycemia Through Increased Glucose Entry into Cells Via AKT/GLUT4 Pathway

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Insulin resistance and type 2 Diabetes mellitus resulting in chronic hyperglycemia is a major health problem in the modern world. Many drugs have been tested to control hyperglycemia which is believed to be the main factor behind many of the diabetes-related late-term complications. Wogonin is a famous herbal medicine which has been shown to be effective in controlling diabetes and its complications. In our previous work, we showed that wogonin is beneficial in many ways in controlling diabetic cardiomyopathy. In this review, we mainly explained wogonin anti-hyperglycemic property through AKT/GLUT4 pathway. Here we briefly discussed that wogonin increases Glut4 trafficking to plasma membrane which allows increased entry of glucose and thus alleviates hyperglycemia.

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Wogonin can be used as an anti-diabetic and anti-hyperglycemic drug and works via AKT/GLUT4 pathway.

During Adipocyte Remodeling, Lipid Droplet Configurations Regulate Insulin Sensitivity through F-Actin and G-Actin Reorganization

Adipocytes have unique morphological traits in insulin sensitivity control. However, how the appearance of adipocytes can determine insulin sensitivity has not been understood. Here, we demonstrate that actin cytoskeleton reorganization upon lipid droplet (LD) configurations in adipocytes plays important roles in insulin-dependent glucose uptake by regulating GLUT4 trafficking. Compared to white adipocytes, brown/beige adipocytes with multilocular LDs exhibited well-developed filamentous actin (F-actin) structure and potentiated GLUT4 translocation to the plasma membrane in the presence of insulin. In contrast, LD enlargement and unilocularization in adipocytes downregulated cortical F-actin formation, eventually leading to decreased F-actin-to-globular actin (G-actin) ratio and suppression of insulin-dependent GLUT4 trafficking. Pharmacological inhibition of actin polymerization accompanied with impaired F/G-actin dynamics reduced glucose uptake in adipose tissue and conferred systemic insulin resistance in mice. Thus, our study reveals that adipocyte remodeling with different LD configurations could be an important factor to determine insulin sensitivity by modulating F/G-actin dynamics.

Serine 474 phosphorylation is essential for maximal Akt2 kinase activity in adipocytes

The Ser/Thr protein kinase Akt regulates essential biological processes such as cell survival, growth, and metabolism. Upon growth factor stimulation, Akt is phosphorylated at Ser⁴⁷⁴; however, how this phosphorylation contributes to Akt activation remains controversial. Previous studies, which induced loss of Ser⁴⁷⁴ phosphorylation by ablating its upstream kinase mTORC2, have implicated Ser⁴⁷⁴ phosphorylation as a driver of Akt substrate specificity. Here we directly studied the role of Akt2 Ser⁴⁷⁴ phosphorylation in 3T3-L1 adipocytes by preventing Ser⁴⁷⁴ phosphorylation without perturbing mTORC2 activity. This was achieved by utilizing a chemical genetics approach, where ectopically expressed S474A Akt2 was engineered with a W80A mutation to confer resistance to the Akt inhibitor MK2206, and thus allow its activation independent of endogenous Akt. We found that insulin-stimulated phosphorylation of four bona fide Akt substrates (TSC2, PRAS40, FOXO1/3a, and AS160) was reduced by ∼50% in the absence of Ser⁴⁷⁴ phosphorylation. Accordingly, insulin-stimulated mTORC1 activation, protein synthesis, FOXO nuclear exclusion, GLUT4 translocation, and glucose uptake were attenuated upon loss of Ser⁴⁷⁴ phosphorylation. We propose a model where Ser⁴⁷⁴ phosphorylation is required for maximal Akt2 kinase activity in adipocytes.