Proteomic analysis of rosiglitazone and guggulsterone treated 3T3-L1 preadipocytes

Modulation of adipogenesis and lipogenesis by indomethacin and pantoprazole

Endocrine disruptors are suggested to act as potential "obesogens" by interacting with various metabolic processes in adipose tissue. Besides industrial chemicals that are blamed for acting as endocrine disruptors as well as obesogens, pharmaceuticals can also cause obesogenic effects as unintended adverse effects. However, limited studies evaluated the obesogenic adverse effects of pharmaceuticals. Based on this information, the present study aimed to investigate the possible in vitro adipogenic/lipogenic potential of indomethacin and pantoprazole that are prescribed during pregnancy. Their effects on lipid accumulation, adiponectin level, glycerol-3-phosphate dehydrogenase (G3PDH) activity, and expression of adipogenic genes and proteins were investigated in 3 T3-L1 cell line. The range of concentrations of the pharmaceuticals was selected according to their Cmax values. Lipid accumulation was increased dependently with indomethacin dose and with pantoprazole at its highest concentration. Both pharmaceuticals also increased adiponectin levels, which was thought to play a role in stimulating the adipogenesis pathway. Moreover, both pharmaceuticals altered the gene and/or protein expression of some adipogenic/lipogenic transcriptional factors, which may lead to disruption of metabolic pathways during the fetal period. In conclusion, indomethacin and pantoprazole may have obesogenic effects through different mechanisms and their potential to cause obesity should be investigated by further in vivo and epidemiological studies.

Hakai, a novel Runx2 interacting protein, augments osteoblast differentiation by rescuing Runx2 from Smurf2-mediated proteasome degradation

Runt-related transcription factor 2 (Runx2) is a key regulator of osteoblast differentiation and bone formation. In Runx2-deficient embryos, skeletal development ceases at the cartilage anlage stage. These embryos die of respiratory failure upon birth and display a complete absence of bone and cartilage mineralization. Here, we identified Hakai, a type of E3 ubiquitin ligase as a potential Runx2 interacting partner through affinity pulldown-based proteomic approach. Subsequently, we observed that similar to Runx2, Hakai was downregulated in osteopenic ovariectomized rats, suggesting its involvement in bone formation. Consistent with this observation, Hakai overexpression significantly enhanced osteoblast differentiation in mesenchyme-like C3H10T1/2 as well as primary rat calvaria osteoblast (RCO) cells in vitro. Conversely, overexpression of a catalytically inactive Hakai mutant (C109A) exhibited minimal to no effect, whereas Hakai depletion markedly reduced endogenous Runx2 levels and impaired osteogenic differentiation in both C3H10T1/2 and RCOs. Mechanistically, Hakai physically interacts with Runx2 and enhances its protein turnover by rescuing it from Smad ubiquitination regulatory factor 2 (Smurf2)-mediated proteasome degradation. Wild-type Hakai but not Hakai-C109A inhibited Smurf2 protein levels through proteasome-mediated degradation. These findings underscore Hakai's functional role in bone formation, primarily through its positive modulation of Runx2 protein turnover by protecting it from Smurf2-mediated ubiquitin-proteasomal degradation. Collectively, our results demonstrate Hakai as a promising novel therapeutic target for osteoporosis.

Carnosic Acid (CA) Induces a Brown Fat-like Phenotype, Increases Mitochondrial Biogenesis, and Activates AMPK in 3T3-L1 Adipocytes

Adipose tissue plays a crucial role in regulating metabolic homeostasis, and its dysfunction in obesity leads to insulin resistance and type 2 diabetes (T2D). White adipose tissue (WAT) primarily stores energy as lipids, while brown adipose tissue (BAT) regulates thermogenesis by dissipating energy as heat. The process of browning involves the transdifferentiation of WAT into brown-like or beige adipocytes, which exhibit a similar phenotype as BAT. The browning of WAT is an attractive approach against obesity and T2D, and the activation of the energy sensor AMP-activated protein kinase (AMPK) has been shown to play a role in browning. Carnosic acid (CA), a polyphenolic diterpene, found in many plants including rosemary, is reported to possess potent antioxidant, anti-inflammatory, and anti-hyperglycemic properties. The limited evidence available indicates that CA activates AMPK and may have anti-obesity and antidiabetic potential; however, the effects in adipocyte browning remain largely unexplored. This study aimed to examine the effects of CA on the markers of adipocyte browning. The treatment of 3T3L1 adipocytes with CA activated AMPK, reduced lipid accumulation, and increased the expression of browning protein markers (UCP-1, PGC-1α, PRDM16, and TFAM) and mitochondrial biogenesis. The use of compound C, an AMPK inhibitor, significantly attenuated the effects of CA, indicating AMPK involvement. These studies demonstrate that CA can activate AMPK and stimulate the browning of white adipocytes. Future animal and human studies are required to examine the effects of CA in vivo.

Hypolipidemic and Antihyperlipidemic Effects of Holarrhena pubescens Methanolic Extract Is Mediated through Inhibition of Lipase Activity and Lipid Accumulation

Holarrhena pubescens seeds are used in the treatment of various diseases, especially diabetes and associated complications, in different parts of the world. The present study was undertaken to determine the hypolipidemic and antihyperlipidemic effects of methanolic extract of H. pubescens seeds in rats. The extract was subjected to LC-MS analysis to determine the chemical constituents. The hypolipidemic action was studied by determining the effect of 28-day oral administration of seed extract on serum cholesterol, serum triglycerides, and serum HDL-cholesterol levels. The antihyperlipidemic action was studied in rats fed with a high-fat diet containing cholesterol and saturated fat, and the same lipid parameters were estimated during 28-day treatment. To elucidate its probable mechanism of action, in vitro studies on the inhibition of lipid accumulation in preadipocytes, DPP-IV inhibitory effect, and lipase enzyme inhibition were studied. The seed extract reduced serum levels of cholesterol and triglycerides in both normal rats and animals fed with a high-fat diet without a significant effect on HDL-cholesterol levels. The seed extract was highly effective in inhibiting lipase enzyme activity but showed a modest effect on the inhibition of lipid accumulation and DPP-IV. The results demonstrated that H. pubescens seed extract has hypolipidemic and antihyperlipidemic effects mediated probably through inhibition of lipase enzyme activity.

Galectin-1 in Obesity and Type 2 Diabetes

Galectin-1 is a carbohydrate-binding protein expressed in many tissues. In recent years, increasing evidence has emerged for the role of galectin-1 in obesity, insulin resistance and type 2 diabetes. Galectin-1 has been highly conserved through evolution and is involved in key cellular functions such as tissue maturation and homeostasis. It has been shown that galectin-1 increases in obesity, both in the circulation and in the adipose tissue of human and animal models. Several proteomic studies have independently identified an increased galectin-1 expression in the adipose tissue in obesity and in insulin resistance. Large population-based cohorts have demonstrated associations for circulating galectin-1 and markers of insulin resistance and incident type 2 diabetes. Furthermore, galectin-1 is associated with key metabolic pathways including glucose and lipid metabolism, as well as insulin signalling and inflammation. Intervention studies in animal models alter animal weight and metabolic profile. Several studies have also linked galectin-1 to the progression of complications in diabetes, including kidney disease and retinopathy. Here, we review the current knowledge on the clinical potential of galectin-1 in obesity and type 2 diabetes.

Screening for anti-adipogenic, pro-lipolytic and thermogenic plant extracts by models associating intestinal epithelial cells with human adipose cells

Purpose

Excessive fat mass accumulation in obesity leads to diverse metabolic disorders, increased risks of cardiovascular diseases and in some cases, mortality. The aim of this study was to screen the actions of botanical extracts intended for oral use on human adipose tissue, using an in vitro screening model combining human intestinal cells with human adipose cells. This was to find the most effective extracts on lipid accumulation, UCP1 expression and ATP production in pre-adipocytes and on adipocyte lipolysis.

Methods

In this study, 25 individual plant extracts were screened for their effects on human adipose cells. Consequently, an original in vitro model was set up using the Caco-2 cell line, to mimic the intestinal passage of the extracts and then exposing human adipose cells to them. The biological actions of extracts were thus characterized, and compared with a coffee extract standard. The most effective extracts, and their combinations, were retained for their actions on lipid accumulation, the expression of the thermogenic effector UCP1 and ATP production in pre-adipocytes as well as on lipolysis activity of mature adipocytes.

Results

The biphasic culture system combining human Caco-2 cells with human adipose cells was verified as functional using the green coffee extract standard. Out of the 25 plant extracts studied, only 7 and their combinations were retained due to their potent effects on adipose cells biology. The data showed that compared to the coffee extract standard, Immortelle, Catechu, Carrot and Rose hip extracts were the most effective in reducing lipid accumulation and increased UCP1 expression in human pre-adipocytes.

Conclusion

This study reveals the potential inhibitory effects on lipid accumulation and thermogenic activity of Immortelle, Catechu, Carrot and Rose hip extracts, and for the first time synergies in their combinations, using an in vitro model mimicking as closely as possible, human intestinal passage linked to adipose cells. These findings need to be confirmed by in vivo trials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02794-8.

Effects of Hyperglycemia and Diabetes Mellitus on Coagulation and Hemostasis

In patients with diabetes, metabolic disorders disturb the physiological balance of coagulation and fibrinolysis, leading to a prothrombotic state characterized by platelet hypersensitivity, coagulation disorders and hypofibrinolysis. Hyperglycemia and insulin resistance cause changes in platelet number and activation, as well as qualitative and/or quantitative modifications of coagulatory and fibrinolytic factors, resulting in the formation of fibrinolysis-resistant clots in patients with diabetes. Other coexisting factors like hypoglycemia, obesity and dyslipidemia also contribute to coagulation disorders in patients with diabetes. Management of the prothrombotic state includes antiplatelet and anticoagulation therapies for diabetes patients with either a history of cardiovascular disease or prone to a higher risk of thrombus generation, but current guidelines lack recommendations on the optimal antithrombotic treatment for these patients. Metabolic optimizations like glucose control, lipid-lowering, and weight loss also improve coagulation disorders of diabetes patients. Intriguing, glucose-lowering drugs, especially cardiovascular beneficial agents, such as glucagon-like peptide-1 receptor agonists and sodium glucose co-transporter inhibitors, have been shown to exert direct anticoagulation effects in patients with diabetes. This review focuses on the most recent progress in the development and management of diabetes related prothrombotic state.

Proteomic analysis of TGFβ-induced A549 secretome identifies putative regulators of epithelial-mesenchymal transition

Imparting epithelial to mesenchymal transition (EMT) during cellular transformation, a major driving force behind tumor progression, is one of the notorious oncogenic activities of transforming growth factor β (TGFβ); however, the secretary factors released during TGFβ-induced EMT that may have role in potentiating EMT and tumor progression are poorly known. This study was undertaken to identify such secreted protein factors from TGFβ-induced A549 cells cultured in serum-free chemically defined medium (Freestyle^TM ) using Matrix Assisted Laser Desorption Ionization-Time of flight/Time of flight (MALDI-TOF/TOF) mass spectrometry. We identified some of the potential factors such as ESR, ANXA2, ALDH1A, TGFβ-induced protein ig-h3, and PAI-1 that were not only secreted but some were also elevated in TGFβ-induced A549 cells. Interestingly, these factors are widely reported to play crucial role in EMT induction and progression, which not only validates our findings but also opens avenues for further investigation, if upon secretion they act exogenously through certain receptors to potentiate cellular signaling involved in EMT induction and tumor progression.

Nano-LC based proteomic approach identifies that E6AP interacts with ENO1 and targets it for degradation in breast cancer cells

E6AP (E6 associated protein) is a HECT domain containing protein having dual E3 ligase and ERα coactivation activity in breast cancer cells. Although E6AP is known to possess antitumorigenic activity, the underlying molecular mechanism is poorly understood. In the present study, we applied nano-LC based proteomics approach to identify E6AP-interacting proteins where we performed GST-pull down using GST-E6AP from whole cell extracts of MCF7 cells, resolved the differentially interacting proteins on 1D-SDS-PAGE, excised the gel bands that were trypsin digested followed by fractionation and spotting on MALDI-TOF/TOF plate through Nano-LC MALDI spotter. Subsequently, fractionated and spotted peptides were identified using MALDI-TOF/TOF. We identified several E6AP interacting proteins including previously reported such as HSP70 and new ones such as Enolase-1. We further confirmed that E6AP and Enolase1 interacted and colocalized more in the cytoplasmic periphery in breast cancer cells and further demonstrated that E6AP also targeted ENO1 for ubiquitin-mediated degradation in these cells.

Annexins in Adipose Tissue: Novel Players in Obesity

Obesity and the associated comorbidities are a growing health threat worldwide. Adipose tissue dysfunction, impaired adipokine activity, and inflammation are central to metabolic diseases related to obesity. In particular, the excess storage of lipids in adipose tissues disturbs cellular homeostasis. Amongst others, organelle function and cell signaling, often related to the altered composition of specialized membrane microdomains (lipid rafts), are affected. Within this context, the conserved family of annexins are well known to associate with membranes in a calcium (Ca²⁺)- and phospholipid-dependent manner in order to regulate membrane-related events, such as trafficking in endo- and exocytosis and membrane microdomain organization. These multiple activities of annexins are facilitated through their diverse interactions with a plethora of lipids and proteins, often in different cellular locations and with consequences for the activity of receptors, transporters, metabolic enzymes, and signaling complexes. While increasing evidence points at the function of annexins in lipid homeostasis and cell metabolism in various cells and organs, their role in adipose tissue, obesity and related metabolic diseases is still not well understood. Annexin A1 (AnxA1) is a potent pro-resolving mediator affecting the regulation of body weight and metabolic health. Relevant for glucose metabolism and fatty acid uptake in adipose tissue, several studies suggest AnxA2 to contribute to coordinate glucose transporter type 4 (GLUT4) translocation and to associate with the fatty acid transporter CD36. On the other hand, AnxA6 has been linked to the control of adipocyte lipolysis and adiponectin release. In addition, several other annexins are expressed in fat tissues, yet their roles in adipocytes are less well examined. The current review article summarizes studies on the expression of annexins in adipocytes and in obesity. Research efforts investigating the potential role of annexins in fat tissue relevant to health and metabolic disease are discussed.

Identification and characterization of phytocannabinoids as novel dual PPARα/γ agonists by a computational and in vitro experimental approach

BACKGROUND

The nuclear Peroxisome Proliferator Activated Receptors (PPARs) are ligand-activated transcription factors playing a fundamental role in energy homeostasis and metabolism. Consequently, functional impairment or dysregulation of these receptors lead to a variety of metabolic diseases. While some phytocannabinoids (pCBs) are known to activate PPARγ, no data have been reported so far on their possible activity at PPARα.

METHODS

The putative binding modes of pCBs into PPARα/γ Ligand Binding Domains were found and assessed by molecular docking and molecular dynamics. Luciferase assays validated in silico predictions whereas the biological effects of such PPARα/γ ligands were assessed in HepG2 and 3T3L1 cell cultures.

RESULTS

The in silico study identified cannabigerolic acid (CBGA), cannabidiolic acid (CBDA) and cannabigerol (CBG) from C. sativa as PPARα/γ dual agonists, suggesting their binding modes toward PPARα/γ isoforms and predicting their activity as full or partial agonists. These predictions were confirmed by luciferase functional assays. The resulting effects on downstream gene transcription in adipocytes and hepatocytes were also observed, establishing their actions as functional dual agonists.

CONCLUSIONS

Our work broadens the activity spectrum of CBDA, CBGA and CBG by providing evidence that these pCBs act as dual PPARα/γ agonists with the ability to modulate the lipid metabolism.

GENERAL SIGNIFICANCE

Dual PPARα/γ agonists have emerged as an attractive alternative to selective PPAR agonists to treat metabolic disorders. We identified some pCBs as dual PPARα/γ agonists, potentially useful for the treatment of dyslipidemia and type 2 diabetes mellitus.

Proteomic profiling of Ganoderma tsugae ethanol extract-induced adipogenesis displaying browning features

Ganoderma is classified as a top grade traditional Chinese medicine for promoting human health by regulating 'vital energy'. Its potency towards metabolism and energy homeostasis, particularly, metabolic adaptations of adipocytes, needs to be re-evaluated through an evidence-based study. Here, the triterpenoid-rich Ganoderma tsugae ethanol extract (GTEE) was found to contribute towards adipogenesis accompanied with elevated intracellular lipid metabolic flux. Additionally, proteomic profiling revealed GTEE-upregulated mitochondrial remodeling and chemical energy redox modifications, which display UCP1-positive browning fat-selective features and a NADH-mediated adaptive mechanism. GTEE-treated mice with diet-induced obesity also resulted in the amelioration of white adipocyte hypertrophy and the appearance of UCP1-positive browning adipocytes. Our novel findings unravel that GTEE could promote intracellular metabolic flexibility and plasticity followed by the induction of adipocyte browning.

Differential expression and accumulation of 14-3-3 paralogs in 3T3-L1 preadipocytes and differentiated cells

The 14-3-3 protein family interacts with more than 2000 different proteins in mammals, as a result of its specific phospho-serine/phospho-threonine binding activity. Seven paralogs are strictly conserved in mammalian species. Here, we show that during adipogenic differentiation of 3T3-L1 preadipocytes, the level of each 14-3-3 protein paralog is regulated independently. For instance 14-3-3β, γ, and η protein levels are increased compared to untreated cells. In contrast, 14-3-3ε protein levels decreased after differentiation while others remained constant. In silico analysis of the promoter region of each gene showed differences that explain the results obtained at mRNA and protein levels.

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14-3-3 paralogs are regulated independently during 3T3-L1 adipogenesis.

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14-3-3β, γ, and η are specifically accumulated during adipogenesis.

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Promoter sequence differences may explain this specific regulation.

Guggulsterone and Its Role in Chronic Diseases

Guggulsterone is a plant sterol derived from gum resin of Commiphora wightii. The gum resin from guggul plants has been used for thousand years in Ayurveda to treat various disorders, including internal tumors, obesity, liver disorders, malignant sores and ulcers, urinary complaints, intestinal worms, leucoderma, sinuses, edema, and sudden paralytic seizures. Guggulsterone has been identified a bioactive components of this gum resin. This plant steroid has been reported to work as an antagonist of certain nuclear receptors, especially farnesoid X receptor, which regulates bile acids and cholesterol metabolism. Guggulsterone also mediates gene expression through the regulation of transcription factors, including nuclear factor-kappa B and signal transducer and activator of transcription 3, which plays important roles in the development of inflammation and tumorigenesis. Guggulsterone has been shown to downregulate the expression of proteins involved in anti-apoptotic, cell survival, cell proliferation, angiogenic, metastatic, and chemoresistant activities in tumor cells. This review aimed to clarify the cell signal pathways targeted by guggulsterone and the bioactivities of guggulsterone in animal models and humans.

Recent advances in proteomic studies of adipose tissues and adipocytes

Obesity is a chronic disease that is associated with significantly increased levels of risk of a number of metabolic disorders. Despite these enhanced health risks, the worldwide prevalence of obesity has increased dramatically over the past few decades. Obesity is caused by the accumulation of an abnormal amount of body fat in adipose tissue, which is composed mostly of adipocytes. Thus, a deeper understanding of the regulation mechanism of adipose tissue and/or adipocytes can provide a clue for overcoming obesity-related metabolic diseases. In this review, we describe recent advances in the study of adipose tissue and/or adipocytes, focusing on proteomic approaches. In addition, we suggest future research directions for proteomic studies which may lead to novel treatments of obesity and obesity-related diseases.

Overexpression of nuclear apoptosis-inducing factor 1 altered the proteomic profile of human gastric cancer cell MKN45 and induced cell cycle arrest at G1/S phase

Nuclear apoptosis-inducing factor 1 (NAIF1) was previously reported to induce apoptosis. Moreover, the expression of NAIF1 was significantly down-regulated in human gastric cancer tissues compared to adjacent normal tissues. However, the mechanism by which the NAIF1 gene induces apoptosis is not fully understood. Our results show that NAIF1 was minimally expressed in all the tested gastric cancer cell lines. Our data also demonstrates that NAIF1 is localized in the nuclei of cells as detected by monitoring the green fluorescence of NAIF1-GFP fusion protein using fluorescent confocal microscopy. Next, a comparative proteomic approach was used to identify the differential expression of proteins between gastric cancer cell lines MKN45/NAIF1 (−) and MKN45/NAIF1 (+). We found five proteins (proteasome 26S subunit 2, proteasome 26S subunit 13, NADH dehydrogenase Fe-S protein 1, chaperonin containing TCP1 subunit 3 and thioredoxin reductase 1) that were up-regulated and three proteins (ribonuclease inhibitor 1, 14-3-3 protein epsilon isoform and apolipoprotein A-I binding protein) that were down-regulated in the MKN45 cells overexpressing NAIF1. We also discovered that NAIF1 could induce cell cycle arrest at G1/S phase by altering the expression of cell cycle proteins cyclinD1, cdc2 and p21. The differentially expressed proteins identified here are related to various cellular programs involving cell cycle, apoptosis, and signal transduction regulation and suggest that NAIF1 may be a tumor suppressor in gastric cancer. Our research provides evidence that elucidates the role of how NAIF1 functions in gastric cancer.

Evaluation of analgesic, antioxidant, cytotoxic and metabolic effects of pregabalin for the use in neuropathic pain

OBJECTIVE

The aim of this research was to evaluate analgesic, antioxidant, metabolic, and cytotoxic effects of pregabalin (PGB), which is widely applied for the treatment of neuropathic pain syndromes in diabetic patients.

METHODS

We used the streptozotocin (STZ) model of painful diabetic neuropathy (PDN) in mice and we measured the effect of intraperitoneally administered PGB on tactile and thermal nociceptive thresholds in the von Frey and hot plate assays, respectively. The influence of PGB on the motor coordination of diabetic animals was investigated in the rotarod test. In vitro in HepG2 and 3T3-L1 cell lines cytotoxicity of PGB, its influence on glucose utilization, and lipid accumulation were assessed. The antioxidant capacity of PGB was evaluated spectrophotometrically using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method.

RESULTS

Pregabalin was a very efficacious antiallodynic and analgesic drug capable of increasing the pain thresholds for tactile allodynia and thermal hyperalgesia in diabetic mice. In the von Frey test at a dose of 30 mg/kg it elevated the pain threshold for 168% versus diabetic control and in the hot plate test this dose prolonged the latency time to pain reaction for 130% versus control value of diabetic mice. No motor deficits were observed in PGB-treated diabetic animals. In vitro PGB did not influence glucose utilization or lipid accumulation. No antioxidant or cytotoxic effects of PGB were observed at concentrations 1-100 μM.

DISCUSSION AND CONCLUSION

Our experiments demonstrated significant antiallodynic and analgesic properties of PGB in mice. In vitro studies showed that this drug is metabolically neutral. It did not cause motor coordination impairments in diabetic animals either. These effects might be of great importance for diabetic patients.

Application of proteomics technology in adipocyte biology

Obesity and its associated complications have reached epidemic proportions in Western-type societies. Concomitantly, the obesity incidence in developing countries is increasing. One hallmark of obesity is the differentiation of pre-adipocytes into mature triglyceride-loaded adipocytes present in subcutaneous and visceral adipose tissue depots. This may ultimately lead to dysfunctional adipose tissue together with detrimental changes in the profiles of (pre-)adipocyte-secreted proteins, known as adipokines. Obesity-induced alterations in adipokine profiles contribute to the development of obesity-associated disorders. Consequently, the interest in the molecular events responsible for adipose tissue modifications during weight gain and weight loss as well as in the aetiology of obesity-associated disorders is growing. Molecular mechanisms involved in pre-adipocyte differentiation and alterations in adipokine profiles have been examined at the gene and protein level by high-throughput technologies. Independent proteomics studies have contributed significantly to further insight into adipocyte biology, particularly with respect to adipokine profiling. In this review novel findings obtained with adipo-proteomics studies are highlighted and the relevance of proteomics technologies to further understand molecular aspects of adipocyte biology is discussed.