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Obesity results in the chronic activation of innate immune system and subsequently sets in diabetes. Aim of the study was to investigate the immunometabolic role of brown adipose tissue (BAT) in the obesity. We performed both BAT transplantation as well as extirpation experiments in the mouse model of high-fat diet (HFD)-induced obesity. We carried out immune cell profiling in the stromal vascular fraction (SVF) isolated from epididymal white adipose tissue (eWAT). BAT transplantation reversed HFD-induced increase in body weight gain and insulin resistance without altering diet intake. Importantly, BAT transplantation attenuated the obesity-associated adipose tissue inflammation in terms of decreased pro-inflammatory M1-macrophages, cytotoxic CD8a T-cells and restored anti-inflammatory regulatory T-cells (Tregs) in the eWAT. BAT transplantation also improved endogenous BAT activity by elevating protein expression of browning markers (UCP-1, PRDM16 and PGC1α) in it. In addition, BAT transplantation promoted the eWAT expression of various genes involved in fatty acid oxidation (such as Elvol3 and Tfam,). In contrast, extirpation of the interscapular BAT exacerbated HFD-induced obesity, insulin resistance and adipose tissue inflammation (by increasing M1 macrophages, CD8a T-cell and decreasing Tregs in eWAT). Taken together, our results suggested an important role of BAT in combating obesity-associated metabolic complications. These results open a novel therapeutic option to target obesity and related metabolic disorders like type 2 diabetes.

Mechanisms underlying postprandial and obesity-associated plasma ghrelin reductions are incompletely understood. Here, using ghrelin cell-selective insulin receptor-KO (GhIRKO) mice, we tested the impact of insulin, acting via ghrelin cell-expressed insulin receptors (IRs), to suppress ghrelin secretion. Insulin reduced ghrelin secretion from cultured gastric mucosal cells of control mice but not from those of GhIRKO mice. Acute insulin challenge and insulin infusion during both hyperinsulinemic-hypoglycemic clamps and hyperinsulinemic-euglycemic clamps lowered plasma ghrelin in control mice but not GhIRKO mice. Thus, ghrelin cell-expressed IRs are required for insulin-mediated reductions in plasma ghrelin. Furthermore, interventions that naturally raise insulin (glucose gavage, refeeding following fasting, and chronic high-fat diet) also lowered plasma ghrelin only in control mice - not GhIRKO mice. Thus, meal- and obesity-associated increases in insulin, acting via ghrelin cell-expressed IRs, represent a major, direct negative modulator of ghrelin secretion in vivo, as opposed to ingested or metabolized macronutrients. Refed GhIRKO mice exhibited reduced plasma insulin, highlighting ghrelin's actions to inhibit insulin release via a feedback loop. Moreover, GhIRKO mice required reduced glucose infusion rates during hyperinsulinemic-hypoglycemic clamps, suggesting that suppressed ghrelin release resulting from direct insulin action on ghrelin cells usually limits ghrelin's full potential to protect against insulin-induced hypoglycemia.

Objective Acyl-ghrelin regulates eating, body weight, blood glucose, and GH secretion upon binding to its receptor GHSR (growth hormone secretagogue receptor; ghrelin receptor). GHSR is distributed in several brain regions and some peripheral cell-types including pituitary somatotrophs. The objective of the current study was to determine the functional significance of acyl-ghrelin's action on GHSR-expressing somatotrophs in mediating GH secretion and several of acyl-ghrelin's metabolic actions. Methods GH-IRES-Cre mice and loxP-flanked (floxed) GHSR mice were newly developed and then crossed to one another to generate mice that lacked GHSR selectively from somatotrophs. Following validation of mice with somatotroph-selective GHSR deletion, metabolic responses of these mice and control littermates were assessed following both acute and chronic acyl-ghrelin administration, a 24-h fast, and a prolonged 60% chronic caloric restriction protocol modeling starvation. Results In mice with somatotroph-selective GHSR deletion, a single peripheral injection of acyl-ghrelin failed to induce GH secretion or increase food intake, unlike wild-type and other littermate control groups. However, the usual acute blood glucose increase in response to the acyl-ghrelin bolus was preserved. Similarly, chronic s.c. acyl-ghrelin administration to mice with somatotroph-selective GHSR deletion failed to increase plasma GH, food intake, or body weight. Physiologically elevating plasma acyl-ghrelin via a 24-h fast also failed to raise plasma GH and resulted in a limited hyperphagic response upon food reintroduction in mice with somatotroph-selective GHSR deletion, although those mice nonetheless did not exhibit an exaggerated reduction in blood glucose. Physiologically elevating plasma acyl-ghrelin via a 15-day caloric restriction protocol which provided only 40% of usual daily calories failed to raise plasma GH in mice with somatotroph-selective GHSR deletion, although those mice did not exhibit life-threatening hypoglycemia. Conclusions These results reveal that direct engagement of GHSR-expressing somatotrophs is required for a peripheral ghrelin bolus to acutely stimulate GH secretion and the actions of chronic acyl-ghrelin delivery and physiological plasma acyl-ghrelin elevations to increase plasma GH. These results also suggest that actions of acyl-ghrelin to increase food intake and body weight are reliant on direct activation of GHSRs expressed on somatotrophs. Furthermore, these results suggest that the glucoregulatory actions of acyl-ghrelin – in particular, its actions to raise blood glucose when acutely administered, prevent small blood glucose drops following a 24-h fast, and avert life-threatening hypoglycemia during an acute-on-chronic caloric restriction protocol – do not depend on GHSR expression by somatotrophs., Graphical abstract Image 1, Highlights • Mice with pituitary somatotroph-selective GHSR deletion were generated. • Somatotroph-expressed GHSRs mediate GH secretion and food intake after acute ghrelin. • Body weight effects of chronic ghrelin infusion require somatotroph-expressed GHSRs. • Somatotroph-expressed GHSRs enable GH to increase upon chronic caloric restriction. • Mice lacking somatotroph GHSRs maintain euglycemia upon chronic caloric restriction.

Obesity and associated metabolic disorders are heading up with an alarming rate in developing nations. One of highly sought solution for metabolic disorders is to identify natural molecule with an ability to reduce obesity and increase insulin sensitivity. Coelogin (CLN) is a phenanthrene derivative isolated from the ethanolic extract of Coelogyne cristata. In our constant efforts to identify novel anti-dyslipidemic and anti-adipogenic compounds using CFPMA (common feature pharmacophore model using known anti-adipogenic compounds) model, predicted possible anti-adipogenic activity of CLN. In vitro results showed significant inhibition of adipogenesis in 3T3-L1 and C3H10T1/2 cell by CLN. It arrests the cell cycle in G1 phase of interphase and inhibits mitotic clonal expansion to regulate adipogenesis. CLN elicits insulin sensitizing effect in mature adipocytes. During extracellular flux assessment studies, it increases oxidative respiration and energy expenditure in adipocytes. In vivo, CLN reversed HFD-induced dyslipidemia as well as insulin resistance in C57BL/6 mice. It promoted the expression of genes involved in improved mitochondrial function and fatty acid oxidation in eWAT. CLN restored energy expenditure and increased the capacity of energy utilization in HFD fed mice. Taken together, the study indicated beneficial effects of CLN in combating obesity-associated metabolic complications.

Various imperative studies support the notion that hyperinsulinemia (HI) itself serves as the common link between adipose tissue inflammation (ATI) and metabolic syndrome. However, the contribution of HI mediated ATI and its metabolic consequences are yet to be explored. We induced chronic HI per se in mice by administration of exogenous insulin for 8 weeks through mini-osmotic pumps. For the reduction of circulating insulin in response to excess calorie intake, we have partially ablated β-cells by using streptozotocin (STZ) in the diet-induced obesity (DIO) and genetic mice models (db/db). Flow cytometry analysis was performed for the quantification of immune cells in stromal vascular fraction (SVF) isolated from epididymal white adipose tissue (eWAT). Our studies demonstrated that chronic HI augmented ATI in terms of elevated pro-inflammatory cells (M1 macrophages and NK-cells) and suppressed anti-inflammatory cells (M2 macrophages, eosinophils and regulatory T-cells). These results were correlated with altered obesity-associated metabolic phenotype. Partial reduction of circulating insulin level attenuated excess calorie-induced ATI and improved insulin sensitivity. Mechanistically, an imbalance in M1 and M2 macrophage proportions in eWAT promoted iNOS (inducible nitric oxide synthase): arginase-1 imbalance that resulted into extracellular matrix (ECM) deposition and insulin resistance (IR) development. However, iNOS-/- mice were protected from HI-induced M1:M2 macrophage imbalance, ECM deposition and IR in adipose tissue. Overall, we conclude that chronic HI per se contributed in ATI and iNOS corroborated ECM deposition.

Chronic low-grade inflammation/meta-inflammation in adipose tissue leads to obesity-associated metabolic complications. Despite growing understanding, the roles of immune cell subsets, their interrelationship, and chronological events leading to progression of obesity-associated insulin resistance (IR) remains unclear. We carried out temporal immunometabolic profiling of adipose tissue from C57BL/6 mice fed a high-fat diet (HFD) for 4, 8, 12, 16, and 20 weeks. We used clodronate sodium liposomes (CLODs) to deplete macrophages and disodium cromoglycate sodium liposomes (DSCGs) to stabilize mast cells. In the temporal HFD settings, mice showed progressive glucose intolerance, insulin resistance, and adipose tissue senescence. Histochemistry analysis of epididymal white adipose tissue (eWAT) using picro-sirius red and Masson’s trichrome staining showed extensive collagen deposition in the 16th and 20th weeks. Flow cytometry analysis of the stromal vascular fraction (SVF) from eWAT revealed T-cell subsets as early-phase components and pro-inflammatory macrophages, as well as mast cells as the later phase components during obesity progression. In our therapeutic strategies, macrophage depletion by CLOD and mast stabilization by DSCG attenuated obesity, adipose tissue fibrosis, and improved whole-body glucose homeostasis. In addition, mast cell stabilization also attenuated senescence (p53 and X-gal staining) in eWAT, signifying the role of mast cells over macrophages during obesity. New-generation mast cell stabilizers can be exploited for the treatment of obesity-associated metabolic complications.

Background and Purpose In our drug discovery program of natural product, earlier we have reported Aegeline that is N-acylated-1-amino-2- alcohol, which was isolated from the leaves of Aeglemarmelos showed anti-hyperlipidemic activity for which the QSAR studies predicted the compound to be the β3-AR agonist, but the mechanism of its action was not elucidated. In our present study, we have evaluated the β3-AR activity of novel N-acyl-1-amino-3-arylopropanol synthetic mimics of aegeline and its beneficial effect in insulin resistance. In this study, we have proposed the novel pharmacophore model using reported molecules for antihyperlipidemic activity. The reported pharmacophore features were also compared with the newly developed pharmacophore model for the observed biological activity. Experimental Approach Based on 3D pharmacophore modeling of known β3AR agonist, we screened 20 synthetic derivatives of Aegeline from the literature. From these, the top scoring compound 10C was used for further studies. The in-slico result was further validated in HEK293T cells co-trransfected with human β3-AR and CRE-Luciferase reporter plasmid for β3-AR activity.The most active compound was selected and β3-AR activity was further validated in white and brown adipocytes differentiated from human mesenchymal stem cells (hMSCs). Insulin resistance model developed in hMSC derived adipocytes was used to study the insulin sensitizing property. 8 week HFD fed C57BL6 mice was given 50 mg/Kg of the selected compound and metabolic phenotyping was done to evaluate its anti-diabetic effect. Results As predicted by in-silico 3D pharmacophore modeling, the compound 10C was found to be the most active and specific β3-AR agonist with EC50 value of 447 nM. The compound 10C activated β3AR pathway, induced lipolysis, fatty acid oxidation and increased oxygen consumption rate (OCR) in human adipocytes. Compound 10C induced expression of brown adipocytes specific markers and reverted chronic insulin induced insulin resistance in white adipocytes. The compound 10C also improved insulin sensitivity and glucose tolerance in 8 week HFD fed C57BL6 mice. Conclusion This study enlightens the use of in vitro insulin resistance model close to human physiology to elucidates the insulin sensitizing activity of the compound 10C and edifies the use of β3AR agonist as therapeutic interventions for insulin resistance and type 2 diabetes.

Defect in insulin signaling leads to the development of insulin resistance followed by type 2 diabetes. Exploiting our previously developed physiological chronic hyperinsulinemia (CI)-mediated insulin resistance (IR) model, we wanted to understand how miRNAs contribute to the development of IR. Amongst the identified and validate miRNAs, the expression of miR-27b was found to be highly upregulated during CI-induced IR in 3T3-L1 adipocytes. We also validated the expression of miR-27b in CI-induced IR in human mesenchymal stem cell (hMSC)-derived adipocytes and in vivo high fat diet (HFD)-induced IR mice model. Bioinformatics target prediction softwares and luciferase reporter assay identified insulin receptor (INSR) as one of a prime target of miR-27b. Lentiviral mediated overexpression of miR-27b impairs insulin signaling by modulating INSR expression that in turn led to decreased glucose uptake in both 3T3-L1 and hMSC-derived adipocytes. Conversely, inhibition of miR-27b reversed CI-mediated suppression of target protein INSR and improved phosphorylation of Akt, a nodal protein of insulin signaling that is impaired by CI treatment. Lentiviral mediated overexpression of miR-27b in in vivo C57BL/6 mice impaired whole body glucose tolerance and adipose tissue insulin sensitivity. Furthermore, inhibition of miR-27b in HFD-induced insulin resistance mice model improved glucose tolerance and adipose tissue insulin sensitivity by increasing the expression of its target gene INSR in eWAT. Thus, our results indicate that miR-27b functions as a prime modulator of CI-induced IR via regulating the expression of INSR. KEY MESSAGES: miR-27b is upregulated in different in vitro and in vivo models of insulin resistance. miR-27b directly suppresses the expression of INSR by targeting 3'UTR of INSR. Modulation of miR-27b expression regulates insulin sensitivity by targeting INSR.

Obesity and dyslipidemia is the two facet of metabolic syndrome, which needs further attention. Recent studies indicate triazole and indole derivatives have remarkable anti-obesity/antidyslipidemic activity. To harness the above-mentioned potential, a series of novel triazole clubbed indole derivatives were prepared using click chemistry and evaluated for anti-adipogenic activity. Based on the structure-activity relationship, essential functional groups which potentiate anti-adipogenic activity were identified. The lead compound 13m exhibited potent anti-adipogenic activity compared to its parent compounds with the IC-50 value of 1.67 μM. Further evaluation of anti-adipogenic activity was conducted in different cell lines such as C3H10T1/2 and hMSC with positive result. The anti-adipogenic effect of compound 13m was most prominent in the early phase of adipogenesis, which is driven by the G1 to S phase cell cycle arrest during mitotic clonal expansion. The mechanistic study suggests that compound 13m exhibit anti-adipogenic property by activating Wnt3a/β-catenin pathway, a known suppressor of key adipogenic genes PPARγ and C/EBPα. It is noteworthy that the compound 13m also reduced serum triglyceride, LDL and total cholesterol in Syrian Golden hamster model of dyslipidemia. The anti-adipogenic activity of compound 13m can also be correlated with decreased expression of PPARγ and increased expression of β-catenin in epididymal white adipose tissue (eWAT) in vivo. The compound 13m also increased the expression of genes involved in reverse cholesterol transport (RCT) such as PPARα and LXR1α indicating another mechanism by which compound 13m ameliorates dyslipidemia in Syrian Golden hamster model. Overall this study provides a unique perspective into the anti-adipogenic/antidyslipidemic property of triazole and indole hybrids molecules with further scope to increase the anti-adipogenic potency for therapeutic intervention of obesity and metabolic syndrome.

A swift increase has been observed in the number of individuals with metabolic syndrome worldwide. A number of natural compounds have been identified towards combating metabolic syndrome. Adding to this premise, here we report the pleiotropic activities of Ecliptal (EC); a natural compound isolated from the herb Eclipta alba. Administration of EC was shown to have prominent anti-adipogenic effects in 3T3-L1 and hMSC derived adipocytes. It was shown to activate Wnt-pathway and alter AKT signaling. Additionally, it caused cell cycle arrest and inhibited mitotic clonal expansion. EC treatment augmented mitochondrial biogenesis as well as function as estimated by expression of PGC1α, UCP-1, mitochondrial complexes and estimation of oxygen consumption rate. EC also reduced LPS-induced inflammation and tunicamycin induced ER stress. Further, EC enhanced insulin sensitivity by increasing AKT phosphorylation, inhibiting PKCα/βII phosphorylation and reducing leptin/adiponectin ratio. Finally, EC administration in Syrian golden hamsters was shown to have potent anti-dyslipidemic effects. Cumulatively, encompassing pleiotropic activities of EC, it could prove to be a potential drug candidate against obesity, insulin resistance and related metabolic syndrome.

Objective The hormone liver-expressed antimicrobial peptide-2 (LEAP2) is a recently identified antagonist and an inverse agonist of the growth hormone secretagogue receptor (GHSR). GHSR's other well-known endogenous ligand, acyl-ghrelin, increases food intake, body weight, and GH secretion and is lowered in obesity but elevated upon fasting. In contrast, LEAP2 reduces acyl-ghrelin-induced food intake and GH secretion and is found elevated in obesity but lowered upon fasting. Thus, the plasma LEAP2/acyl-ghrelin molar ratio could be a key determinant modulating GHSR signaling in response to changes in body mass and feeding status. In particular, LEAP2 may serve to dampen acyl-ghrelin action in the setting of obesity, which is associated with ghrelin resistance. Here, we sought to determine the metabolic effects of genetic LEAP2 deletion. Methods We generated the first known LEAP2-KO mouse line. Food intake, GH secretion, and cellular activation (c-fos induction) in different brain regions following s.c. acyl-ghrelin administration in LEAP2-KO mice and wild-type littermates were determined. LEAP2-KO mice and wild-type littermates were submitted to a battery of tests (such as measurements of body weight, food intake, and body composition; indirect calorimetry, determination of locomotor activity, and meal patterning while housed in metabolic cages) over the course of 16 weeks of high-fat diet and/or standard chow feeding. Fat accumulation was assessed in hematoxylin & eosin-stained and oil red O-stained liver sections from these mice. Results LEAP2-KO mice were more sensitive to s.c. ghrelin. In particular, acyl-ghrelin acutely stimulated food intake at a dose of 0.5 mg/kg BW in standard chow-fed LEAP2-KO mice while a 2× higher dose was required by wild-type littermates. Also, acyl-ghrelin stimulated food intake at a dose of 1 mg/kg BW in high-fat diet-fed LEAP2-KO mice while not even a 10× higher dose was effective in wild-type littermates. Acyl-ghrelin induced a 90.9% higher plasma GH level and 77.2–119.7% higher numbers of c-fos-immunoreactive cells in the arcuate nucleus and olfactory bulb, respectively, in LEAP2-KO mice than in wild-type littermates. LEAP2 deletion raised body weight (by 15.0%), food intake (by 18.4%), lean mass (by 6.1%), hepatic fat (by 42.1%), and body length (by 1.7%) in females on long-term high-fat diet as compared to wild-type littermates. After only 4 weeks on the high-fat diet, female LEAP2-KO mice exhibited lower O2 consumption (by 13%), heat production (by 9.5%), and locomotor activity (by 49%) than by wild-type littermates during the first part of the dark period. These genotype-dependent differences were not observed in high-fat diet-exposed males or female and male mice exposed for long term to standard chow diet. Conclusions LEAP2 deletion sensitizes lean and obese mice to the acute effects of administered acyl-ghrelin on food intake and GH secretion. LEAP2 deletion increases body weight in females chronically fed a high-fat diet as a result of lowered energy expenditure, reduced locomotor activity, and increased food intake. Furthermore, in female mice, LEAP2 deletion increases body length and exaggerates the hepatic fat accumulation normally associated with chronic high-fat diet feeding., Graphical abstract Image 1, Highlights • A novel line of LEAP2-knockout mice was generated. • LEAP2 deletion sensitizes mice to the GH secretory effects of administered ghrelin. • LEAP2 deletion reduces ghrelin resistance in diet-induced obese mice. • HFD-fed female LEAP2-KO mice eat more and gain more body weight and hepatic fat. • HFD-fed female LEAP2-KO mice exhibit lowered energy expenditure and activity.

Leptin, following its discovery, has developed a formidable interest in the scientific community to delineate its contribution towards overall metabolic homeostasis. Contradictory reports have been published on leptin administration effects on whole body insulin sensitivity. Following late reports, we surveyed human serum leptin levels along with other metabolic parameters including BMI and HOMA-IR. We found a positive correlation between leptin levels and insulin resistance parameters. Considering the presence of the long form of leptin receptor on adipocytes, we explored the effects of chronic physiological hyper-leptinemic exposure on adipocyte insulin sensitivity. Chronic leptin (50ng/ml) treatment in 3T3-L1 adipocytes decreased insulin-induced phosphorylation of nodal insulin signaling proteins along with reduced glucose uptake. Metabolic flux studies indicated mitochondrial dysfunction and reduced oxygen consumption rate. Leptin treatment also increased both cellular and mitochondrial superoxide levels concomitant to increased expression of nitric oxide synthase-2 (NOS2). Further, pharmacological depletion of NOS2 reversed leptin mediated effects on insulin signaling. In-vivo implantation of leptin osmotic pumps in C57BL/6 mice also decreased insulin responsiveness. Interestingly, these effects were lacking in NOS2 knockout strain. In conclusion, our studies put forward a potential link between leptin and adipocyte insulin responsiveness in an NOS2 dependent manner.

Background Adipocyte dysfunction, obesity and associated metabolic disorders are of prime healthcare concern worldwide. Among available medications, natural products and inspired molecules hold 40% space in clinically prescribed medicines. In queue, this study overcomes the drawback of curcumin's low bioavailability with potent anti-adipogenic and anti-dyslipidemic activity. Methods To evaluate the role of CDPP on adipocyte differentiation, 3T3-L1 adipocytes were used as an in-vitro model. Flow cytometry was performed for cell cycle analysis. Syrian golden hamsters were used to study pharmacokinetic profile and dyslipidemic activity exhibited by CDPP. Result CDPP was found to be a potent inhibitor of adipogenesis in-vitro. It blocked mitotic clonal expansion by causing cell cycle arrest. CDPP showed marked improvement in gastrointestinal stability and bioavailability in-vivo as compared to curcumin. Administration of CDPP (100 mg/kg) significantly improved HFD induced dyslipidemic profile in hamsters and activated reverse cholesterol transport machinery. Conclusion CDPP could be used as a potential drug candidate against adipogenesis and dyslipidemia with enhanced gastrointestinal stability and bioavailability.

Background The hormone ghrelin stimulates food intake, promotes adiposity, increases body weight, and elevates blood glucose. Consequently, alterations in plasma ghrelin levels and the functioning of other components of the broader ghrelin system have been proposed as potential contributors to obesity and diabetes. Furthermore, targeting the ghrelin system has been proposed as a novel therapeutic strategy for obesity and diabetes. Scope of review The current review focuses on the potential for targeting ghrelin and other proteins comprising the ghrelin system as a treatment for obesity and diabetes. The main components of the ghrelin system are introduced. Data supporting a role for the endogenous ghrelin system in the development of obesity and diabetes along with data that seemingly refute such a role are outlined. An argument for further research into the development of ghrelin system-targeted therapeutic agents is delineated. Also, an evidence-based discussion of potential factors and contexts that might influence the efficacy of this class of therapeutics is provided. Major conclusions It would not be a “leap to” conclusions to suggest that agents which target the ghrelin system – including those that lower acyl-ghrelin levels, raise LEAP2 levels, block GHSR activity, and/or raise desacyl-ghrelin signaling – could represent efficacious novel treatments for obesity and diabetes., Highlights • We review the potential of targeting the ghrelin system to treat obesity and diabetes. • The main components of the ghrelin system are introduced. • We present data for and against roles of the ghrelin system in obesity and diabetes. • We discuss factors that might influence the efficacy of this class of therapeutics.

Insulin resistance is associated with deregulation of insulin signaling owing to the chronic exposure of insulin (hyperinsulinemia) to the tissues. Phosphorylation and dephosphorylation events in insulin signaling pathway play an essential role in signal transduction and glucose uptake. Amongst all, Akt protein is considered to be central to the overall insulin signaling proteins. In glucose responsive tissues like adipose and muscles, activation of Akt is responsible for triggering GLUT4 translocation and glucose transport. Several phosphatases such as PTEN, PP2A have been reported to be involved in dephosphorylation and inactivation of Akt protein. We have identified increased PP2A activity during state of chronic hyperinsulinemia exposure along-with development of adipocyte insulin resistance. This increased phosphatase activity leads activation of cAMP/PKA axis, which in turn increased cAMP levels in insulin resistant (IR) adipocytes. Okadaic acid, an inhibitor of PP2A restored and increased insulin stimulated glucose uptake in insulin resistant (IR) and insulin sensitive (IS) adipocytes respectively. In IS adipocyte, chemical activation of PP2A through MG132 and FTY720 showed decreased insulin sensitivity corroborated with decreased Akt phosphorylation and glucose uptake. We also observed an increased expression of PP2A-B (regulatory) subunit in IR adipocytes. We found PPP2R5B, a regulatory subunit of PP2A is responsible for the dephosphorylation and inactivation of Akt protein. Increased expression of PPP2R5B was also confirmed in white adipose tissue of high fat diet induced IR mice model. Overexpression and suppression strategies confirmed the role of PPP2R5B in regulating insulin signaling. Thus, we conclude that PPP2R5B, a B subunit of PP2A is a negative regulator of Akt phosphorylation contributing partly to the chronic hyperinsulinemia induced insulin resistance in adipocytes.

miRNA has been known to regulate diverse cellular and molecular functions. In the earlier study, we have reported that adipocytes differentiated from human mesenchymal stem cells (hMSC) on 72-h chronic insulin (CI) treatment exhibit insulin resistance (IR). Present study has further explored above model to investigate the role of early expressed miRNAs within human adipocytes to modulate differential adipokine expression as observed during IR. Our results highlight that miR-876-3p regulate glucose homeostasis and its dysregulation leads to IR. We found that miR-876-3p level is a critical determinant of adiponectin expression by virtue of its target within adiponectin 3′UTR. Regulatory effect of miR-876-3p impacts crosstalk between adiponectin and insulin signaling. Rosiglitazone treatment in CI-induced IR adipocytes drastically reduced miR-876-3p expression and increased adiponectin level. In line with this, lentiviral-mediated inhibition of miR-876-3p expression ameliorated CI and high-fat diet (HFD)-induced IR in adipocytes differentiated from hMSC and C57BL/6 mice, respectively. Our findings thus suggest that modulating miR-876-3p expression could provide novel opportunities for therapeutic intervention of obesity-associated metabolic syndrome.

Design and synthesis of protein tyrosine phosphatases-1B (PTP1B) inhibitors are important for the drugs targeted to treat diabetes and obesity. The pharmacophore modeling, docking and scaffold hopping techniques have been applied to discover the novel PTP1B inhibitors. The ten prioritized compounds (115-119, 120-121, 127, 130-131) from the library of 86 compounds were synthesized and found positive in the micro molar range for PTP1B in-vitro inhibitory assays as compared to Suramin (IC50 9.5 μM). Among these five active compounds (115-119) were tested in STZ-s induced diabetic rat model and the most active compound 115 in this test, was further tested in C57BL/KsJ-db/db mice where it significantly improved OGTT along with the fasting and random blood glucose level. The treatment by the compound 115 significantly improved the insulin resistance and insulin signaling by restoring the insulin level and normalizing the serum lipid profile. Compound 115 also augmented the insulin action by modulating the expression of genes involved in insulin signaling like IRS 1-2, PI3K, PTPN1, Akt2, AMPK and PPAR-α. Western blot analysis of both skeletal muscle and liver demonstrated that proteins and intermediate enzymes of insulin signaling were also increased as compared to control group. The compound 115 was also investigated for anti-adipogenic effect on 3T3L-1 cells. The compound 115 inhibited MDI induced lipid accumulation in a dose-dependent manner. The oral bioavailability of compound 115 was ∼10.29% after 30 mg/kg oral dosing assessed in rat.

The growing pandemics of diabetes have become a real threat to world economy. Hyperinsulinemia and insulin resistance are closely associated with the pathophysiology of type 2 diabetes. In pretext of brown adipocytes being considered as the therapeutic strategy for the treatment of obesity and insulin resistance, we have tried to understand the effect of hyperinsulinemia on brown adipocyte function. We here with for the first time report that hyperinsulinemia-induced insulin resistance in brown adipocyte is also accompanied with reduced insulin sensitivity and brown adipocyte characteristics. CI treatment decreased expression of brown adipocyte-specific markers (such as PRDM16, PGC1α, and UCP1) and mitochondrial content as well as activity. CI-treated brown adipocytes showed drastic decrease in oxygen consumption rate (OCR) and spare respiratory capacity. Morphological study indicates increased accumulation of lipid droplets in CI-treated brown adipocytes. We have further validated these findingsin vivoin C57BL/6 mice implanted with mini-osmotic insulin pump for 8weeks. CI treatment in mice leads to increased body weight gain, fat mass and impaired glucose intolerance with reduced energy expenditure and insulin sensitivity. CI-treated mice showed decreased BAT characteristics and function. We also observed increased inflammation and ER stress markers in BAT of CI-treated animals. The above results conclude that hyperinsulinemia has deleterious effect on brown adipocyte function, making it susceptible to insulin resistance. Thus, the above findings have greater implication in designing approaches for the treatment of insulin resistance and diabetes via recruitment of brown adipocytes.

In our efforts to develop safe and active chemical entities from nature, we first identified poliothrysoside (1), a phytoconstituent isolated from Flacourtia indica, possessing antidiabetic potential. Subsequently, fifteen derivatives (2-16) were synthesized to assess the activity profile of this class. All the compounds were analyzed for their glucose uptake potency in chronic insulin-induced insulin resistant 3T3-L1 adipocytes. Interestingly, compound 2 exhibited strong ability to increase the insulin sensitivity, primarily activating the AMPK signaling pathway and also inhibited the adipogenesis in 3T3-L1 adipocytes, in concentration dependent manner. Overall, these studies suggest the potential of poliothrysoside and its derivatives as promising leads for non-insulin dependent type 2 diabetes (T2D).

According to the World Health Organization obesity is defined as the excessive accumulation of fat, which increases risk of other metabolic disorders such as insulin resistance, dyslipidemia, hypertension, cardiovascular diseases, etc. There are two types of adipose tissue, white and brown adipose tissue (BAT) and the latter has recently gathered interest of the scientific community. Discovery of BAT has opened avenues for a new therapeutic strategy for the treatment of obesity and related metabolic syndrome. BAT utilizes accumulated fatty acids for energy expenditure; hence it is seen as one of the possible alternates to the current treatment. Moreover, browning of white adipocyte on exposure to cold, as well as with some of the pharmacological agents presents exciting outcomes and indicates the feasibility of transdifferentiation. A better understanding of molecular pathways and differentiation factors, those that play a key role in transdifferentiation are of extreme importance in designing novel strategies for the treatment of obesity and associated metabolic disorders.

Background: Cucumis melo ssp. agrestis var. agrestis (CMA) is a wild variety of C. melo. This study aimed to explore anti-dyslipidemic and anti-adipogenic potential of CMA. Materials and Methods: For initial anti-dyslipidemic and antihyperglycemic potential of CMA fruit extract (CMFE), male Syrian golden hamsters were fed a chow or high-fat diet with or without CMFE (100 mg/kg). Further, we did fractionation of this CMFE into two fractions namely; CMA water fraction (CMWF) and CMA hexane fraction (CMHF). Phytochemical screening was done with liquid chromatography-mass spectrometry LC- (MS)/MS and direct analysis in real time-MS to detect active compounds in the fractions. Further, high-fat diet fed dyslipidemic hamsters were treated with CMWF and CMHF at 50 mg/kg for 7 days. Results: Oral administration of CMFE and both fractions (CMWF and CMHF) reduced the total cholesterol, triglycerides, low‐density lipoprotein cholesterol, and very low‐density lipoprotein-cholesterol levels in high fat diet-fed dyslipidemic hamsters. CMHF also modulated expression of genes involved in lipogenesis, lipid metabolism, and reverse cholesterol transport. Standard biochemical diagnostic tests suggested that neither of fractions causes any toxicity to hamster liver or kidneys. CMFE and CMHF also decreased oil-red-O accumulation in 3T3-L1 adipocytes. Conclusion: Based on these results, it is concluded that CMA possesses anti-dyslipidemic and anti-hyperglycemic activity along with the anti-adipogenic activity. SUMMARY The oral administration of Cucumis melo agrestis fruit extract (CMFE) and its fractions (CMWF and CMHF) improved serum lipid profile in HFD fed dyslipidemic hamsters.CMFE, CMWF and CMHF significantly attenuated body weight gain and eWAT hypertrophy.The CMHF decreased lipogenesis in both liver and adipose tissue.CMFE and CMHF also inhibited adipogenesis in 3T3-L1 adipocytes. Abbreviation used: CMA: Cucumis melo ssp. agrestis var. agrestis, CMFE: CMA fruit extract, CMWF: CMA water fraction, CMHF: CMA hexane fraction, FAS: Fatty acid synthase, SREBP1c: Sterol regulatory element binding protein 1c, ACC: Acetyl CoA carboxylase, LXR α: Liver X receptor α.

Serious hepatic and cardiovascular complications after treatment with the thiazolidinedione (TZD) class of insulin sensitizers have significantly retarded the advancement of new TZD-based peroxisome proliferator-activated receptor agonists that bind with high affinity and selectivity. The aim of the present study is to design new antihyperglycemic agents that promote insulin sensitivity through partial adipogenesis as well as demonstrate beneficial hepatoprotective activity. The results indicated that among forty screened compounds, three of the novel pyranones at a dose of 10 μM increased the preadipocyte differentiation into adipocytes in 3T3-L1 cell lines. They showed an insulin-sensitizing effect by significantly increasing the glucose uptake and exhibited insulin resistance reversal. These compounds at a dose of 20 mg kg−1 significantly protected against thioacetamide-induced hepatotoxic changes in the serum biochemistry as compared to standard hepatoprotectant silymarin and also ameliorated the histopathological alterations in the liver tissues after acute liver injury in Swiss mice.