AMP-activated Protein Kinase Research Articles

Cardiovascular and nonalcoholic fatty liver disease: Sharing common ground through SIRT1 pathways

As a non-communicable disease, cardiovascular disorders have become the leading cause of death for men and women. Of additional concern is that cardiovascular disease is linked to chronic comorbidity disorders that include nonalcoholic fatty liver disease (NAFLD). NAFLD, also termed metabolic-dysfunction-associated steatotic liver disease, is the greatest cause of liver disease throughout the world, increasing in prevalence concurrently with diabetes mellitus (DM), and can progress to nonalcoholic steatohepatitis that leads to cirrhosis and liver fibrosis. Individuals with metabolic disorders, such as DM, are more than two times likely to experience cardiac disease, stroke, and liver disease that includes NAFLD when compared individuals without metabolic disorders. Interestingly, cardiovascular disorders and NAFLD share a common underlying cellular mechanism for disease pathology, namely the silent mating type information regulation 2 homolog 1 (SIRT1; Saccharomyces cerevisiae ). SIRT1, a histone deacetylase, is linked to metabolic pathways through nicotinamide adenine dinucleotide and can offer cellular protection though multiple avenues, including trophic factors such as erythropoietin, stem cells, and AMP-activated protein kinase. Translating SIRT1 pathways into clinical care for cardiovascular and hepatic disease can offer significant hope for patients, but further insights into the complexity of SIRT1 pathways are necessary for effective treatment regimens.

A special issue of Essays in Biochemistry on AMPK and AMPK-related kinases

Abstract In eukaryotic cells, AMP-activated protein kinase (AMPK) plays a central role in responding to nutrient limitation by switching-off ATP-consuming (anabolic) pathways and switching-on ATP generating (catabolic) pathways. Over the last 30 years or so, a considerable body of research has been carried out that has provided us with a wealth of knowledge regarding the regulation and role of AMPK. Despite this, there is still much to learn about AMPK and the field remains highly active, with many groups around the world continuing to explore new roles for AMPK, providing insight into its biological function. This review series was inspired by recent AMPK-focused meetings in Scotland (2022) and Australia (2023) and draws on some of the research presented at those meetings.

AMP-Activated Protein Kinase Treatment Ameliorates Chronic Restraint Stress Induced Memory Impairment in Early Adolescent Rat by Restoring Metabolite Profile and Synaptic Proteins

AMP-Activated Protein Kinase Treatment Ameliorates Chronic Restraint Stress Induced Memory Impairment in Early Adolescent Rat by Restoring Metabolite Profile and Synaptic Proteins

Humanin-G Ameliorates Hemorrhage-Induced Acute Lung Injury in Mice Through AMPKα1-Dependent and -Independent Mechanisms

Background/Objectives: The severity of acute lung injury is significantly impacted by age and sex in patients with hemorrhagic shock. AMP-activated protein kinase (AMPK) is a crucial regulator of energy metabolism but its activity declines with aging. Humanin is a mitochondrial peptide that exerts cytoprotective effects in response to oxidative stressors and is associated with longevity. Using a mouse model of hemorrhagic shock that mimics the clinical condition of adult patients, we investigated whether treatment with a humanin analog, humanin-G, mitigates lung injury and whether its mechanisms of action are dependent on the catalytic AMPKα1 subunit activation. Methods: Male and female AMPKα1 wild-type (WT) and knock-out (KO) mice (8–13 months old) were subjected to hemorrhagic shock by blood withdrawal, followed by resuscitation with shed blood and lactated Ringer’s solution. The mice were treated with PEGylated humanin-G or vehicle and euthanized 3 h post-resuscitation. Results: Sex- and genotype-related differences were observed after hemorrhagic shock as lung neutrophil infiltration was more pronounced in the male AMPKα1 WT mice than the female WT mice; also, the male AMPKα1 KO mice experienced a significant decline in mean arterial blood pressure when compared to the male WT mice after resuscitation. The scores of histological lung injury were similarly elevated in all the male and female AMPKα1 WT and KO mice when compared to the control mice. At molecular analysis, acute lung injury was associated with the downregulation of AMPKα1/α2 catalytic subunits in the WT mice, whereas an increased activation of the signal transducer and activator of transcription-3 (STAT3) was observed in all the vehicle-treated groups. The in vivo administration of humanin-G ameliorated histological lung damage in all the groups of animals and ameliorated mean arterial blood pressure in the male AMPKα1 KO mice. The in vivo administration of humanin-G lowered lung neutrophil infiltration in the male and female AMPKα1 WT mice only but not in the KO mice. The beneficial results of humanin-G correlated with the lung cytosolic and nuclear activation of AMPKα in the male and female AMPKα1 WT groups, whereas STAT3 activation was not modified. Conclusions: In adult age, hemorrhage-induced acute lung injury manifests with sex-dependent characteristics. Humanin-G has therapeutic potential and the AMPKα1subunit is an important requisite for its inhibitory effects on lung leucosequestration, but not for the amelioration of lung alveolar structure or the hemodynamic effects of the peptide.

Improvement of osteogenic differentiation potential of placenta-derived mesenchymal stem cells by metformin via AMPK pathway activation.

Placenta-derived human mesenchymal stem cells (PL-MSCs) have gained a lot of attention in the field of regenerative medicine due to their availability and bone-forming capacity. However, the osteogenic differentiation capacity of these cells remains inconsistent and could be improved to achieve greater efficiency. Although metformin, a widely used oral hypoglycemic agent, has been shown to increase bone formation in various cell types, its effect on osteogenic differentiation of PL-MSCs has not yet been investigated. Therefore, the objective of this study was to examine the effect of metformin on the osteogenic differentiation capacity of PL-MSCs and the underlying mechanisms. The PL-MSCs were treated with 0.5 to 640µM metformin and their osteogenic differentiation capacity was examined by an alkaline phosphatase (ALP) activity assay, Alizarin red S staining and expression levels of osteogenic genes. The role of adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling in mediating the effect of metformin on the osteogenic differentiation capacity of PL-MSCs was also investigated by determining levels of phosphorylated AMPK(pAMPK)/AMPK ratio and by using compound C, an AMPK inhibitor. The results showed that 10-160µM metformin significantly increased the viability of PL-MSCs in a dose- and time-dependent manner. Furthermore, 80-320µM metformin also increased ALP activity, matrix mineralization, and expression levels of osteogenic genes, runt-related transcription factor 2 (RUNX2), osterix (OSX), osteocalcin (OCN) and collagen I (COL1), in PL-MSCs. Metformin increases osteogenic differentiation of PL-MSCs, at least in part, through the AMPK signaling pathway, since the administration of compound C inhibited its enhancing effects on ALP activity, matrix mineralization, and osteogenic gene expression of PL-MSCs. This study demonstrated that metformin at concentrations of 80-320μM significantly enhanced osteogenic differentiation of PL-MSCs in a dose- and time-dependent manner, primarily through activation of the AMPK signaling pathway. This finding suggests that metformin could be used with other conventional drugs to induce bone regeneration in various bone diseases. Additionally, this study provides valuable insights for future osteoporosis treatment by highlighting the potential of modulating the AMPK pathway to improve bone regeneration.

Experimentally-driven mathematical model to understand the effects of matrix deprivation in breast cancer metastasis.

Normal epithelial cells receive proper signals for growth and survival from attachment to the underlying extracellular matrix (ECM). They perceive detachment from the ECM as a stress and die - a phenomenon termed as 'anoikis'. However, metastatic cancer cells acquire anoikis-resistance and circulate through the blood and lymphatics to seed metastasis. Under normal (adherent) growth conditions, the serine-threonine protein kinase Akt stimulates protein synthesis and cell growth, maintaining an anabolic state in the cancer cell. In contrast, previously we showed that the stress due to matrix deprivation is sensed by yet another serine-threonine kinase, AMP-activated protein kinase (AMPK), that inhibits anabolic pathways while promoting catabolic processes. We illustrated a switch from Akthigh/AMPKlow in adherent condition to AMPKhigh/Aktlow in matrix-detached condition, with consequent metabolic switching from an anabolic to a catabolic state, which aids cancer cell stress-survival. In this study, we utilized these experimental data and developed a deterministic ordinary differential equation (ODE)-based mechanistic mathematical model to mimic attachment-detachment signaling network. To do so, we used the framework of insulin-glucagon signaling with consequent metabolic shifts to capture the pathophysiology of matrix-deprived state in breast cancer cells. Using the developed metastatic breast cancer signaling (MBCS) model, we identified perturbation of several signaling proteins such as IRS, PI3K, PKC, GLUT1, IP3, DAG, PKA, cAMP, and PDE3 upon matrix deprivation. Further, in silico molecular perturbations revealed that several feedback/crosstalks like DAG to PKC, PKC to IRS, S6K1 to IRS, cAMP to PKA, and AMPK to Akt are essential for the metabolic switching in matrix-deprived cancer cells. AMPK knockdown simulations identified a crucial role for AMPK in maintaining these adaptive changes. Thus, this mathematical framework provides insights on attachment-detachment signaling with metabolic adaptations that promote cancer metastasis.

Glucose Upregulates ChREBP via Phosphorylation of AKT and AMPK to Modulate MALT1 and WISP1 Expression.

Glucose can activate the carbohydrate response element binding protein (ChREBP) transcription factor to control gene expressions in the metabolic pathways. The way of ChREBP involvement in human prostate cancer development remains undetermined. This study examined the interactions between prostate fibroblasts and cancer cells under the influences of ChREBP. Results showed that high glucose (30 mM) increased the phosphorylation of AKT at S473 and AMP-activated protein kinase (AMPK) at S485 in human prostate fibroblast (HPrF) cells and prostate cancer PC-3 cells. High glucose enhanced the expression of ChREBP, which increased the expressions of fibronectin, alpha-smooth muscle actin (α-SMA), and WNT1 inducible signaling pathway protein 1 (WISP1), magnifying the cell growth and contraction in HPrF cells in vitro. The cell proliferation, invasion, and tumor growth in prostate cancer PC-3 cells were enhanced by inducing the expressions of ChREBP, mucosa-associated lymphoid tissue 1 (MALT1), and epithelial-mesenchymal transition markers with high glucose treatment. Moreover, ectopic ChREBP overexpression induced NF-κB signaling activities via upregulating MALT1 expression in PC-3 cells. Our findings illustrated that ChREBP is an oncogene in the human prostate. High glucose condition induces a glucose/ChREBP/MALT1/NF-κB axis which links the glucose metabolism to the NF-κB activation in prostate cancer cells, and a glucose/ChREBP/WISP1 axis mediating autocrine and paracrine signaling between fibroblasts and cancer cells to promote cell migration, contraction, growth, and invasion of the human prostate.

L-aspartate ameliorates diet-induced obesity by increasing adipocyte energy expenditure.

Obesity always leads to profound perturbation of metabolome. Metabolome studies enrich the knowledge on associations between endogenous metabolites and obesity, potentially providing innovative strategies for the development of novel anti-obesity pharmacotherapy. This study aims to identify an endogenous metabolite that regulates energy expenditure and to explore its application for obesity treatment. C57BL/6 mice were fed with a high-fat and high-cholesterol (HFC) diet, comprising 60% fat and 1.2% cholesterol, for 12 weeks to induce obesity. Significant metabolites were identified in the livers of both health and obese mice through comparative hepatic metabolomics analysis. Correlation between serum or adipose L-aspartate level and body weight in obese mice, as well as human body mass index (BMI), was evaluated. In addition, saline or 200 mg/kg L-aspartate was orally administrated to HFC diet mice and HFC diet-induced obese mice for 6-7 weeks. Body weight, adipose tissue weight, glucose tolerance and liver damage were assessed to evaluate the effect on obesity prevention and treatment. Comprehensive lab animal monitoring system (CLAMS) and seahorse assay were employed to investigate the regulatory effect of L-aspartate on energy metabolism in vivo and in vitro, respectively. 3T3-L1 preadipocytes and murine white adipose tissue (WAT) were utilized to examine the impact of L-aspartate on adipocyte adipogenesis and lipogenesis and cellular signalling pathway in vitro and in vivo. L-aspartate, an approved drug for liver injury and chronic fatigue, was identified as an endogenous inducer of energy expenditure. Serum or adipose L-aspartate levels were found to be negatively correlated with the severity of obesity in both humans and mice. Administration of L-aspartate to HFC diet mice led to a significant reduction in body weight, with decreases of 14.5% in HFC diet mice and 8.5% in HFC diet-induced obese mice, respectively. In addition, the treatment improved related metabolic syndrome (Figure 2 and Figure S3). These therapeutics were associated with enhancements in whole-body energy expenditure and suppression of adipocyte adipogenesis along with activation of Adenosine 5'-monophosphate-activated protein kinase (AMPK) signalling pathway. L-aspartate may serve as a novel endogenous inducer of energy expenditure and suppressor of adipogenesis and lipogenesis along with activation of AMPK, thereby offering a promising therapeutic strategy for obesity prevention and treatment.

Avenanthramides Ameliorate Insulin Resistance by Modulating Gluconeogenesis and Glycogen Synthesis in HepG2 Cells.

Diabetes mellitus (DM) is a multifaceted metabolic condition, mainly defined by elevated blood glucose levels. A feature of type 2 DM includes insulin resistance (IR), which involves impairments within the insulin signaling pathways. Avenanthramides (AVNs) are phenolic alkaloids found in Avena sativa L. The major AVNs are AVN A, AVN B, and AVN C. They have been reported to offer benefits in preventing inflammation, cancer, and cardiovascular diseases. However, the effects of AVNs on the liver glucose metabolism pathways remain unknown. This study examined the effects and underlying mechanisms through which AVNs alleviate IR induced by free fatty acid (FFA) in HepG2 cells. The results indicated that FFA treatment significantly decreased glucose consumption by 34.54% compared to the control. However, treatments with AVN A, B, and C at 100 μM increased glucose uptake by 57.93%, 58.28%, and 53.10%, respectively, compared to FFA treatment alone. This effect occurs through the increased expression of glucose transporter 4. Furthermore, AVNs significantly enhanced the glycogen content. AVNs induced increased phosphorylation of insulin receptor substrate-1 (IRS-1), phosphatidylinositol-3-kinase (PI3K), and protein kinase B (Akt). AVNs treatment decreased the levels of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase in HepG2 cells. This effect was attributed to AMP-activated protein kinase activation and inhibition of forkhead box protein O1. Collectively, these results suggest that AVNs regulate glucose metabolism by activating the IRS-1/PI3K/Akt pathway, which is related to glycogen synthesis, and by inhibiting key molecules that promote gluconeogenesis.

Knockdown of hepatic mitochondrial calcium uniporter mitigates MASH and fibrosis in mice

BackgroundMitochondrial calcium uniporter (MCU) plays pleiotropic roles in cellular physiology and pathology that contributes to a variety of diseases, but the role and potential mechanism of MCU in the pathogenesis of metabolic dysfunction-associated steatohepatitis (MASH) remain poorly understood.Methods and resultsHere, hepatic knockdown of MCU in C57BL/6J mice was achieved by tail vein injection of AAV8-mediated the CRISPR/Cas9. Mice were fed a Choline-deficient, L-amino acid-defined high-fat diet (CDAHFD) for 8 weeks to induce MASH and fibrosis. We find that expression of MCU enhanced in MASH livers of humans and mice. MCU knockdown robustly limits lipid droplet accumulation, steatosis, inflammation, and hepatocyte apoptotic death during MASH development both in vivo in mice and in vitro in cellular models. MCU-deficient mice strikingly mitigate MASH-related fibrosis. Moreover, the protective effects of MCU knockdown against MASH progression are accompanied by a reduced level of mitochondrial calcium, limiting hepatic oxidative stress, and attenuating mitochondrial dysfunction. Mechanically, RNA sequencing analysis and protein immunoblotting indicate that knockdown MCU inhibited the Hippo/YAP pathway activation and restored the AMP-activated protein kinase (AMPK) activity during MASH development both in vitro and in vivo.ConclusionsMCU is up-regulated in MASH livers in humans and mice; and hepatic MCU knockdown protects against diet-induced MASH and fibrosis in mice. Thus, targeting MCU may represent a novel therapeutic strategy for MASH and fibrosis.Graphical

Gastrodin ameliorates diabetic nephropathy by activating the AMPK/Nrf2 pathway.

Diabetic nephropathy (DN) is a leading cause of end-stage kidney failure, contributing to elevated morbidity and mortality rates in individuals with diabetes. Despite its potential renoprotective effects, the molecular mechanism by which gastrodin (GSTD) impacts DN remains unclear. To investigate this, mice were initially induced with DN via intraperitoneal streptozotocin (STZ) injection (50mg/kg) and subsequently treated with varying doses of GSTD (5, 10, 20mg/kg). Furthermore, the potential molecular mechanism of GSTD in mitigating DN was explored in vivo in conjunction with compound C, an inhibitor of 5'-AMP-activated protein kinase (AMPK). Subsequently, the blood weight, fasting blood glucose levels, and renal injury markers of DN-afflicted mice were assessed. Additionally, renal tissues were subjected to quantitative reverse-transcriptase-polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) to evaluate inflammatory factor levels, colorimetric assays to measure renal malondialdehyde (MDA) levels, and immunoblotting analysis to examine AMPK/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. The results demonstrated that a 6-week GSTD regimen effectively improved metabolic manifestations associated with DN, including reductions in fasting blood glucose levels, 24-hour urine output, renal indices, amelioration of glomerular histopathological abnormalities, diminished glycogen accumulation, and fibrosis. Furthermore, DN-afflicted renal tissues exhibited decreased MDA levels and elevated expression of AMPK/Nrf2 pathway-associated proteins. The beneficial effects of GSTD on DN and its protein modulation were reversed upon co-intervention with compound C. Together, our findings imply that GSTD improves DN by activating the AMPK/Nrf2 pathway, thereby mitigating STZ-induced renal damage, inflammatory responses, and oxidative stress.

Cannabidiol Enhances Mitochondrial Metabolism and Antioxidant Defenses in Human Intestinal Epithelial Caco-2 Cells

Background: The reintroduction of hemp production has resulted in increased consumption of cannabidiol (CBD) products, particularly CBD oil, yet their effects on intestinal health are not fully understood. Proper mitochondrial function and antioxidant defenses are vital for maintaining the intestinal epithelial barrier. AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor gamma coactivator (PGC)1α are key mediators of mitochondrial metabolism. Methods & Results: Using Caco-2 cells, we found that CBD oil promoted AMPK phosphorylation, upregulated differentiation markers, and enhanced PGC1α/SIRT3 mitochondrial signaling. CBD oil reduced reactive oxygen species production and increased antioxidant enzymes. Moreover, CBD oil also increased levels of citrate, malate, and succinate—key metabolites of the tricarboxylic acid cycle—alongside upregulation of pyruvate dehydrogenase and isocitrate dehydrogenase 1. Similarly, pure CBD induced metabolic and antioxidant signaling. Conclusions: CBD enhances mitochondrial metabolic activity and antioxidant defense in Caco-2 cells, making it a promising candidate for treating intestinal dysfunction.

Shear stress-stimulated AMPK couples endothelial cell mechanics, metabolism, and vasodilation.

Endothelial cells respond to mechanical force by stimulating cellular signaling, but how these pathways are linked to elevations in cell metabolism and whether metabolism supports the mechanical response remains poorly understood. Here, we show that the application of force to endothelial cells stimulates VE-cadherin to activate liver kinase B1 (LKB1) and AMP-activated protein kinase (AMPK), a master regulator of energy homeostasis. VE-cadherin stimulated AMPK increases eNOS activity and localization to the plasma membrane, reinforcement of the actin cytoskeleton and cadherin adhesion complex, and glucose uptake. We present evidence for the increase in metabolism being necessary to fortify the adhesion complex, actin cytoskeleton, and cellular alignment. Together these data extend the paradigm for how mechanotransduction and metabolism are linked to include a connection to vasodilation, thereby providing new insight into how diseases involving contractile, metabolic, and vasodilatory disturbances arise.

High intensity interval training as a therapy: Mitophagy restoration in breast cancer

Recent studies have highlighted the role of mitophagy in tumorigenesis. This study aimed to investigate the effects of high-intensity interval training (HIIT) on mitophagy in tumor tissues of mice with breast cancer. Twenty-eight female BALB/c mice were randomly assigned to four groups: Healthy Control (CO), Cancer (CA), Exercise (EX), and Cancer + Exercise (CA + EX). Mammary tumors were induced in the CA and CA + EX groups via 4T1 cell injections. Upon confirmation of tumor formation, the EX and CA + EX groups underwent 8 weeks (40 sessions) of HIIT, comprising 4–10 intervals of running at 80–100 % of maximum speed. The expression levels of mitophagy-related proteins, including parkin, PTEN-induced putative kinase 1 (PINK1), NIP3-like protein X (NIX), BCL2 interacting protein-3 (BINP3), microtubule-associated protein light chain 3-I (LC3-I), microtubule-associated protein light chain 3-II (LC3-II), AMP-activated protein kinase (AMPK), Unc-51 like autophagy activating kinase-1 (ULK1), and sirtuin-1 (SIRT1), were measured in breast and tumor tissues. Tumor volume relative to body weight was assessed weekly during the eight-week HIIT intervention. Protein expression of parkin, PINK1, NIX, BINP3, LC3-II, LC3-I, AMPK, ULK1, and SIRT1 was reduced in the breast tissue of the CA group, while HIIT restored expression levels across all measured variables (P < 0.01). Additionally, tumor volume relative to body weight was significantly lower in the CA + EX group compared to the CA group from weeks 3–8 (P < 0.01). These findings suggest that breast cancer suppresses mitophagy, yet HIIT effectively reverses this suppression, potentially reducing tumor burden. HIIT may thus represent a promising therapeutic strategy for managing breast cancer.

Inhibition of SGLT2 protects podocytes in diabetic kidney disease by rebalancing mitochondria-associated endoplasmic reticulum membranes

BackgroundSodium-glucose cotransporter 2 (SGLT2) inhibitors have changed the therapeutic landscape for diabetic kidney disease (DKD) patients, but their underlying mechanisms are complicated and not fully understood. Mitochondria-associated endoplasmic reticulum membranes (MAMs), the dynamic contact sites between mitochondria and the endoplasmic reticulum (ER), serve as intracellular platforms important for regulating cellular fate and function. This study explored the roles and mechanisms of SGLT2 inhibitors in regulating MAMs formation in diabetic podocytes.MethodsWe assessed MAMs formation in podocytes from DKD patients’ renal biopsy samples and induced an increase in MAMs formation in cultured human podocytes by transfecting OMM-ER linker plasmid to investigate the effects of MAMs imbalance on podocyte injury. Empagliflozin-treated diabetic mice and podocyte-specific SGLT2 knockout diabetic mice (diabetic states were induced by streptozotocin and a high-fat diet), empagliflozin-treated podocytes, SGLT2-downregulated podocytes, and SGLT2-overexpressing podocytes were used to investigate the effects and mechanisms of SGLT2 inhibitors on MAMs formation in diabetic podocytes.ResultsMAMs were increased in podocytes and were associated with renal dysfunction in DKD patients. Increased MAMs aggravated HG-induced podocyte injury. The expression of SGLT2 was increased in diabetic podocytes. In addition, empagliflozin-treatment and podocyte-specific SGLT2 knockout attenuated MAMs formation and podocyte injury in diabetic mice. Empagliflozin treatment and SGLT2 knockdown decreased podocyte MAMs formation by activating the AMP-activated protein kinase (AMPK) pathway, while SGLT2 overexpression had the opposite effect.ConclusionsInhibition of SGLT2 attenuates MAMs imbalance in diabetic podocytes by activating the AMPK pathway. This study expands our knowledge of the roles of SGLT2 inhibitors in improving DKD podocyte injury and provides new insights into DKD treatment.

Snake Venom in Anticancer Drug Development: Potential Targets and Current Perspectives

Many animals active secretions have been used to create novel medications to treat ailments such as hypertension and cancer. Snake venom toxins have made major contributions to treating various medical disorders. There have been several research studies that have been published characterizing and clarifying snake venom's anti-cancer potential. Cancer treatment is one of the primary applications for protein peptides and enzymes derived from various animal species. When separated, several of these proteins, peptides, and enzymes from snake venom and assessed may bind selectively to cancer cell membranes, influencing migration and invasion. These cells proliferation Some of the chemicals discovered in snake venom have a high potential. Cystatin-rich snake venom influences tumor invasion and metastasis. A non-cholinesterase Arginine ester hydrolase enzyme in snake venom reported to have increased sensitivity to chemotherapy and radiotherapy in animal models. Snake thrombin-like enzymes, are serine proteases found in snake venom that causes haemostasis and hypofibrinogenemia. Cancer-associated fibroblasts was reported to have role in quiescence and also prevents cancer cell migration, in addition to downregulating the epithelial-mesenchymal transitioning. Collagen Tumor-associated hyaluronic acid (HA) and hyaluronidase (HAase) was crucial for tumor growth and metastasis promotion. Phospholipases are enzymes that break down phospholipids, which are key components of cell membranes are involved in cancer cell migration, invasion and metastasis. AMP-activated protein kinase (AMPK), a metabolic protein plays a crucial role in energy regulation and cell survival and studies reported its role in tumour suppression. The components of snake venom and its potential as a cancer-fighting agent, we summarised the key findings in this review.

Rab2A-mediated Golgi-lipid droplet interactions support very-low-density lipoprotein secretion in hepatocytes.

Lipid droplets (LDs) serve as crucial hubs for lipid trafficking and metabolic regulation through their numerous interactions with various organelles. While the interplay between LDs and the Golgi apparatus has been recognized, their roles and underlying mechanisms remain poorly understood. Here, we reveal the role of Ras-related protein Rab-2A (Rab2A) in mediating LD-Golgi interactions, thereby contributing to very-low-density lipoprotein (VLDL) lipidation and secretion in hepatocytes. Mechanistically, our findings identify a selective interaction between Golgi-localized Rab2A and 17-beta-hydroxysteroid dehydrogenase 13 (HSD17B13) protein residing on LDs. This complex facilitates dynamic organelle communication between the Golgi apparatus and LDs, thus contributing to lipid transfer from LDs to the Golgi apparatus for VLDL2 lipidation and secretion. Attenuation of Rab2A activity via AMP-activated protein kinase (AMPK) suppresses the Rab2A-HSD17B13 complex formation, impairing LD-Golgi interactions and subsequent VLDL secretion. Furthermore, genetic inhibition of Rab2A and HSD17B13 in the liver reduces the serum triglyceride and cholesterol levels. Collectively, this study provides a new perspective on the interactions between the Golgi apparatus and LDs.

Therapeutic utility of Perfluorocarbon Oxygent in limiting the severity of subarachnoid hemorrhage in mice

Subarachnoid hemorrhage (SAH) is the deadliest form of hemorrhagic stroke; however, effective therapies are still lacking. Perfluorocarbons (PFCs) are lipid emulsion particles with great flexibility and their much smaller size as compared to red blood cells (RBCs) allows them to flow more efficiently within the blood circulation. Due to their ability to carry oxygen, a specific PFC-based emulsion, PFC-Oxygent, has been used as a blood substitute; however, its role in cerebral blood flow regulation is unknown. Adult C57BL/6 wildtype male mice were subjected to an endovascular perforation model of SAH followed by an intravenous (i.v.) injection of 9 ml/kg PFC-Oxygent or no treatment at 5 h after SAH. At 48 h after SAH, functional and anatomical outcomes were assessed. We found that SAH resulted in significant neurologic and motor deficits which were prevented by PFC-Oxygent treatment. We found that SAH-induced vasospasm, reduced RBC deformability, and augmented endothelial dysfunction were also restricted by PFC-Oxygent treatment. Moreover, mitochondrial activity and fusion proteins were also markedly decreased as assessed by oxidative phosphorylation (OXPHOS) after SAH. Interestingly, PFC-Oxygent treatment brought the mitochondrial activity close to the basal level. Moreover, SAH attenuated the level of phosphorylated AMP-activated protein kinase (pAMPK), whereas PFC treatment improved pAMPK levels. These data show the beneficial effects of PFC-Oxygent in limiting the severity of SAH. Further studies are needed to fully understand the mechanism through which PFC-Oxygent exerts its beneficial effects in limiting SAH severity.

Chitosan oligosaccharides: A potential therapeutic agent for inhibiting foam cell formation in atherosclerosis

Foam cell formation is a key hallmark in atherosclerosis and associated cardiovascular diseases (CVDs). The potential anti-atherosclerotic potential of chitosan oligosaccharides (COS) was investigated using oxLDL-treated RAW264.7 murine cells. COS treatment led to a significant inhibition of lipid accumulation, as demonstrated by Oil Red O staining, and reduced levels of total cholesterol, free cholesterol, cholesterol esters, and triglycerides in.oxLDL-treated RAW264.7 cells. COS blocked cholesterol influx through down-regulating class A1 scavenger receptors (SR-A1) and cluster of differentiation 36 (CD36) expression and stimulated cholesterol efflux through up-regulating ABC transporters ABCA-1 and ABCG-1 expressions. Additionally, COS treatment stimulated nuclear signaling pathways involving peroxisome proliferator-activated receptor-γ (PPAR-γ) and liver X receptor α (LXR-α), and also led to the phosphorylation of AMP-activated protein kinase (AMPK). COS further demonstrated anti-inflammatory effects by inhibiting the production of pro-inflammatory cytokines and the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in oxLDL-treated RAW264.7 cells, through suppression of NF-κB signaling. Furthermore, COS alleviated oxidative stress induced by oxLDL by activating Nrf2 signaling and enhancing the expression of antioxidant genes, including heme oxygenase-1 (HO-1), superoxide dismutase (SOD), glutathione peroxidase (Gpx), and catalase (CAT). In conclusion, COS can be beneficial in preventing atherosclerosis and related diseases.

ULK1-regulated AMP sensing by AMPK and its application for the treatment of chronic kidney disease

Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a central kinase involved in energy homeostasis. Increased intracellular AMP levels result in AMPK activation through the binding of AMP to the γ-subunit of AMPK. Recently, we reported that AMP-induced AMPK activation is impaired in the kidneys in chronic kidney disease (CKD) despite an increase in the AMP/ATP ratio. However, the mechanisms by which AMP sensing is disrupted in CKD are unclear. Here, we identified mechanisms of energy homeostasis in which Unc-51-like kinase 1 (ULK1)-dependent phosphorylation of AMPKγ1 at Ser260/Thr262 promoting AMP sensitivity of AMPK. AMPK activation by AMP was impaired in Ulk1 knockout mice despite an increased AMP/ATP ratio. ULK1 expression is markedly downregulated in CKD kidneys, leading to AMP sensing failure. Additionally, MK8722, an allosteric AMPK activator, stimulated AMPK in the kidneys of a CKD mouse model (5/6th nephrectomy) via a pathway that is independent of AMP sensing. Thus, our study shows that MK8722 treatment significantly attenuates the deterioration of kidney function in CKD and may be a potential therapeutic option in CKD therapeutics.