Human Adiponectin Research Articles

Adipo-R1 and adipo-R2 expression in colorectal adenomas and carcinomas.

Human adiponectin (ApN), a 30 kDa glycoprotein of 244-amino acids which is predominantly produced by adipocytes, exerts its effects via two receptors, namely adiponectin receptor-1 (adipo-R1) and adiponectin receptor-2 (adipo-R2) with differential binding affinity to globular adiponectin. Adiponectin receptor expression has been studied in several cancer tissues. However, there are no studies of colorectal adenomas which are considered to be precursors for colorectal carcinoma (CRC). In the present study, the expression of adipo-R1 and adipo-R2 was investigated immunohistochemically in colorectal adenomas and colorectal carcinoma tissues in an attempt to determine associations with these tumors. The study enrolled 50 CRC patients with tumor resection and 82 patients who were diagnosed with adenomatous polyps, classified as negative for neoplasia, low-grade dysplasia (L-GD) or high- grade dysplasia (H-GD). Expression of both adipo-R1 and adipo-R2 was found to be significantly lower in the CRCs than in colorectal adenomas (tubular and tubulovillous, p=0.009 and p<0.001, respectively). Adipo-R1 and adipo-R2 expression was also significantly lower in the CRC group when compared with the groups of patients with low grade dysplasia, high-grade dysplasia or no neoplasia (p=0.012 and p<0.001, respectively). In addition, it was observed that adipo-R2 expression was generally positive in the non-neoplastic group irrespective of the adipo-R2 expression. In the L-GD, H-GD and CRC groups, the adipo-R2 result was positive whenever adipo-R1 result was positive but some patients with negative adipo-R1 had positive adipo-R2 (p<0.001, p=0.004, p<0.001, respectively). This study indicated that ApN may play a role in the progression of colorectal adenomatous polyps to carcinoma through actions on adipo-R1 and adipo-R2 receptors.

Expression, purification, crystallization, and preliminary X-ray crystallographic studies of the human adiponectin receptors, AdipoR1 and AdipoR2.

The adiponectin receptors (AdipoR1 and AdipoR2) are membrane proteins with seven transmembrane helices. These receptors regulate glucose and fatty acid metabolism, thereby ameliorating type 2 diabetes. The full-length human AdipoR1 and a series of N-terminally truncated mutants of human AdipoR1 and AdipoR2 were expressed in insect cells. In small-scale size exclusion chromatography, the truncated mutants AdipoR1Δ88 (residues 89–375) and AdipoR2Δ99 (residues 100–386) eluted mostly in the intact monodisperse state, while the others eluted primarily as aggregates. However, gel filtration chromatography of the large-scale preparation of the tag-affinity-purified AdipoR1Δ88 revealed the presence of an excessive amount of the aggregated state over the intact state. Since aggregation due to contaminating nucleic acids may have occurred during the sample concentration step, anion-exchange column chromatography was performed immediately after affinity chromatography, to separate the intact AdipoR1Δ88 from the aggregating species. The separated intact AdipoR1Δ88 did not undergo further aggregation, and was successfully purified to homogeneity by gel filtration chromatography. The purified AdipoR1Δ88 and AdipoR2Δ99 proteins were characterized by thermostability assays with 7-diethylamino-3-(4-maleimidophenyl)-4-methyl coumarin, thin layer chromatography of bound lipids, and surface plasmon resonance analysis of ligand binding, demonstrating their structural integrities. The AdipoR1Δ88 and AdipoR2Δ99 proteins were crystallized with the anti-AdipoR1 monoclonal antibody Fv fragment, by the lipidic mesophase method. X-ray diffraction data sets were obtained at resolutions of 2.8 and 2.4 Å, respectively.

Adiponectin: Probe of the molecular paradigm associating diabetes and obesity.

Type 2 diabetes is an emerging health challenge all over the world as a result of urbanization, high prevalence of obesity, sedentary lifestyle and other stress related factors compounded with the genetic prevalence. The health consequences and economic burden of the obesity and related diabetes mellitus epidemic are enormous. Different signaling molecules secreted by adipocytes have been implicated in the development of obesity and associated insulin resistance in type 2 diabetes. Human adiponectin, a 244-amino acid collagen-like protein is solely secreted by adipocytes and acts as a hormone with anti-inflammatory and insulin-sensitizing properties. Adiponectin secretion, in contrast to secretion of other adipokines, is paradoxically decreased in obesity which may be attributable to inhibition of adiponectin gene transcription. There are several mechanisms through which adiponectin may decrease the risk of type 2 diabetes, including suppression of hepatic gluconeogenesis, stimulation of fatty acid oxidation in the liver, stimulation of fatty acid oxidation and glucose uptake in skeletal muscle, and stimulation of insulin secretion. To date, no systematic review has been conducted that evaluate the potential importance of adiponectin metabolism in insulin resistance. In this review attempt has been made to explore the relevance of adiponectin metabolism for the development of diabetes mellitus. This article also identifies this novel target for prospective therapeutic research aiming successful management of diabetes mellitus.

Dolphins and diabetes: applying one health for breakthrough discoveries.

Dolphins and diabetes: applying one health for breakthrough discoveries.

Association of adiponectin receptor (Adipo-R1/-R2) expression and colorectal cancer.

Human adiponectin (ApN) is a 30 kDa glycoprotein of 244-amino acids which is extensively produced by adipocytes. ApN acts via two receptors, namely adiponectin receptor-1 (Adipo-R1) and adiponectin receptor-2 (Adipo-R2). Studies have shown the presence of Adipo-R1 and Adipo-R2 expression immunohistochemically in human colorectal cancers (CRCs). However, only a few studies exist which investigated effects of adiponectin receptor expression on CRC characteristics. In the present study, we aimed to explore Adipo-R1/-R2 expression in human colorectal cancers and any association with clinicopathological characteristics and survival. The study enrolled 58 colorectal cancer patients with tumor resection and a control group of 30 subjects with normal colon mucosa. Positivity for Adipo-R1/-R2 expression was significantly more common in the control group in comparison to the patient group (both p<0.001). There was no significant association between Adipo-R1/-R2 expression and clinicopathological characteristics including age, sex tumor location, pTNM stage, Duke's stage, metastasis, histological differentiation, perineural invasion, venous invasion sex, lymphatic invasion, cancer-related mortality, tumor size and recurrence. Adipo- R1/-R2 positivity was also not significantly linked to progression-free or overall survival [p values (0.871, 0.758 ) and (0.274, 0.232), respectively]. Although significantly reduced Adipo-R1/-R2 expression was found in colorectal cancer patients, it had no influence on survival.

GW25-e0249 Treatment of Myocardial Infarction by Transplantation of Adiponectin Gene-Modified Stromal Vascular Fraction cells from Adipose Tissue

The aim of this study was to investigate the effect of the human adiponectin (Hapm1) gene-modified stromal vascular fraction (SVF) cells (Hapm1-SVF) transplantation on the cardiac function and histological changes of heart tissue in rats with myocardial infarction. Rats were divided into four

Measurement of salivary adiponectin concentrations in dogs

Measurement of salivary adiponectin could improve understanding of this adipokine's physiology, and its role in various clinical conditions. The purpose of the study was to evaluate the utility of a human adiponectin ELISA kit for measurement of salivary adiponectin in dogs, to compare serum and salivary adiponectin concentrations in a healthy dog population, and to evaluate possible effects of tooth-cleaning on serum and salivary adiponectin concentrations in dogs. For analytical validation, precision, accuracy, and lower limit of quantification of the assay were determined with saliva samples. In addition, adiponectin concentrations were quantified in serum and saliva samples from 24 healthy dogs, and from 7 dogs with mild gingivitis before and after a tooth-cleaning procedure. The validation assays for salivary adiponectin had all coefficients of variation <15%, and recovery ranged from 85% to 120%. In the linearity test, interference was observed when measuring adiponectin in saliva, but this was solved by diluting samples 1:4. In healthy dogs, salivary and serum adiponectin concentrations were positively correlated (r=.650; P=.009). After the tooth-cleaning procedure, salivary adiponectin concentration increased on day 0 (P=.004), but by day 14, concentrations were less than prior to the procedure (P=.041). The human adiponectin ELISA kit can be used for precise and accurate salivary adiponectin measurement in dogs. Salivary adiponectin increased 24hours after tooth-cleaning, possibly due to acute inflammation or adiponectin leakage from the blood after gingival trauma.

Effect of monomeric adiponectin on cardiac function and perfusion in anesthetized pig.

Adiponectin, the most abundant adipokine released by adipose tissue, appears to play an important role in the regulation of vascular endothelial and cardiac function. To date, however, the physiological effects of human monomeric adiponectin on the coronary vasculature and myocardial systo-diastolic function, as well as on parasympathetic/sympathetic involvement and nitric oxide (NO) release, have not yet been investigated. Thus, we planned to determine the primary in vivo effects of human monomeric adiponectin on coronary blood flow and cardiac contractility/relaxation and the related role of autonomic nervous system, adiponectin receptors, and NO. In 30 anesthetized pigs, human monomeric adiponectin was infused into the left anterior descending coronary artery at constant heart rate and arterial blood pressure, and the effects on coronary blood flow, left ventricular systo-diastolic function, myocardial oxygen metabolism, and NO release were examined. The mechanisms of the observed hemodynamic responses were also analyzed by repeating the highest dose of human monomeric adiponectin infusion after autonomic nervous system and NO blockade, and after specific adiponectin 1 receptor antagonist administration. Intracoronary human monomeric adiponectin caused dose-related increases of coronary blood flow and cardiac function. Those effects were accompanied by increased coronary NO release and coronary adiponectin levels. Moreover, the vascular effects of the peptide were prevented by blockade of β2-adrenoceptors and NO synthase, whereas all effects of human monomeric adiponectin were prevented by adiponectin 1 receptor inhibitor. In conclusion, human monomeric adiponectin primarily increased coronary blood flow and cardiac systo-diastolic function through the involvement of specific receptors, β2-adrenoceptors, and NO release.

Chemical synthesis of human adiponectin(19–107) bearing post-translational glycosylation

Human adiponectin(19–107), which consists of the variable region and the collagenous domain bearing post-translational modifications including glycosylation, was chemically synthesized for the first time. A glycoside of 5-hydroxylysine (Hyl) was incorporated using an α-d-glucopyranosyl-(1→2)-β-d-galactopyranosyl/Hyl-Gly building block in a benzyl-protected form by solid-phase peptide synthesis (SPPS). The molecule was assembled from four segments prepared by SPPS via native chemical ligation (NCL) and thioester methods.

Maternal upper‐body circumferences predict human milk adiponectin concentration (131.8)

Prenatal measures explain little of human milk adiponectin (HMA) variation. We examined whether postpartum metabolic and fat depot measures predict HMA from milk sampled concurrently. Participants underwent a morning oral glucose tolerance test, anthropometry (hip, iliac crest, waist, and under‐breast circumferences; weight and BMI), and breast expression (N=20). Serum insulin, glucose, and total adiponectin were assayed, and insulin sensitivity and secretion were estimated. HMA was assayed using ELISA. Spearman rank coefficients and linear regression were used to examine relations with HMA. Serum adiponectin was the single significant metabolic correlate with HMA (r=0.45, p=0.048). HMA was not significantly correlated with BMI or weight, but became more negatively correlated with fat‐depot specific anthropometry with increasing proximity to the breast: hip (r=‐0.32, p=0.164); iliac crest (r=‐0.46, p=0.039); waist (r=‐0.50, p=0.025); under breast (r=‐0.56, p=0.011). Combined, serum adiponectin and waist circumference predicted 47% of HMA variation (p=0.002). Thus, upper body fat depots may be an important source of HMA independent of circulating adiponectin levels.Grant Funding Source: NIH 8 ULI TR000077

Differential effects of adiponectin in osteoblast-like cells

The skeleton should maintain an adequate volume, vigour and strength to carry out the role for which it is designed: to hold the whole soft tissue mass that shapes the body and to protect the vital organs. To fulfil this task a satisfactory food intake is required and regulators that are released in the feeding and fasting states, among other signals indicate how much soft mass needs to be built up. Those signals include the secretion of adipocytokines which could represent a relevant link between soft mass (adipose tissue) and skeleton. We studied the presence of adiponectin receptors (AdipoR1, AdipoR2) and its direct effects in osteosarcoma cell line Saos-2. The results indicated that adiponectin receptors were present in the osteoblastic cells with a higher expression of AdipoR1. Human recombinant globular adiponectin was able to increase viability levels and decrease cytotoxicity rates in cell cultures. Also, adiponectin significantly inhibited alkaline phosphatase activity in supernatants. Osteoprotegerin mRNA expression was significantly reduced after 72 h treatment. The FOS induction was studied and the results exhibited a significant increase caused by adiponectin. In conclusion, all these observations suggest that adiponectin influences bone metabolism decreasing the levels of bone formation. Regulators of adiponectin or its receptors could be circulating to modulate the activities of this peptide.

Adiponectin retards the progression of diabetic nephropathy in db/db mice by counteracting angiotensin II.

Adiponectin is a multifunctional adipokine with insulin‐sensitizing, anti‐inflammatory, and vasoprotective properties. Epidemiology studies have, however, shown that high levels of serum adiponectin are associated with kidney disease progression. We, therefore, examined the effect of adiponectin administration on the progression of glomerulosclerosis in the obese diabetic (db/db) mouse, a model of type II diabetes. Recombinant human adiponectin was administered intraperitoneally at a dose of 30 or 150 μg per day from weeks 18 to 20. Rosiglitazone administered by gavage at 20 mg/kg body weight (BW) daily served as a therapeutic control. Untreated uninephrectomized db/db mice developed progressive albuminuria and glomerular matrix expansion, associated with increased expression of transforming growth factor beta 1 (TGFβ1), plasminogen activator inhibitor type 1 (PAI‐1), collagen I (Col I), and fibronectin (FN). Treatment with adiponectin at either dose reduced the increases in albuminuria and markers of renal fibrosis seen in db/db mice, without affecting BW and blood glucose. Renal expressions of tumor necrosis factor‐α (TNF‐α) and monocyte‐chemoattractant protein‐1 (MCP‐1) and urinary TNF‐α levels, the markers of renal inflammation, were increased in diabetic mice, whereas adiponectin treatment significantly reduced the levels of these markers. Furthermore, adiponectin obliterated the stimulatory effects of angiotensin II (Ang II), but not the total effect of TGFβ1, on the mRNA expression of PAI‐1, Col I, and FN by cultured glomerular mesangial cells. These observations suggest that adiponectin treatment reduces glomerulosclerosis resulting from type II diabetes probably through its anti‐inflammatory and angiotensin–antagonistic effects. Thus, adiponectin has therapeutic implications in the prevention of progression of diabetic nephropathy.

A common single nucleotide polymorphism impairs B-cell activating factor receptor's multimerization, contributing to common variable immunodeficiency

A common single nucleotide polymorphism impairs B-cell activating factor receptor's multimerization, contributing to common variable immunodeficiency

Abstract 9907: Cardiac Adiponectin Resistance Develops Early After MI and Contributes to Heart Failure Progression

Deficiency of adiponectin (APN), a cardioprotective adipokine, as a risk factor of cardiovascular disease is well-defined. Recent clinical studies report that plasma APN levels are increased in heart failure (HF) patients, suggesting APN resistance might be another unrecognized risk factor. However, direct evidence supporting cardiac APN resistance during HF progression is currently lacking. Adult male mice were subjected to HF by coronary artery occlusion. The biological functions of APN were determined during the course of HF development (0-6 weeks). Plasma APN levels were reduced 3 days post-MI (P&lt;0.01), gradually recovered thereafter, and reached a level greater than control 14 days post-MI (P&lt;0.05). Consistent with APN level reduction, cardiac AMPK phosphorylation (a readout of APN intracellular signaling) was decreased 3 days post-MI (P&lt;0.05). However, cardiac AMPK phosphorylation remained lower than control 14 days post-MI (P&lt;0.01), despite significantly increased plasma APN levels at this time, suggesting reduced cardiac response to endogenous APN. APN administration via osmotic pump beginning 14 days post-MI for the remaining duration of MI did not protect against MI/R injury, in contrast to numerous previous studies demonstrating the cardioprotective effects of APN in acute MI/R. At the molecular level, APN treatment significantly increased both GLUT4 membrane recruitment and 18 F-FDG uptake in the normal heart (P&lt;0.01). However, these responses were dramatically reduced 14-days post-MI. To gain more direct evidence demonstrating impaired cardiomyocyte response to APN during HF development, left ventricular cardiomyocytes were isolated from normal or MI mice (14 days), and incubated with human recombinant APN. APN-induced AMPK phosphorylation and PKA activation were significantly reduced in CM from MI mice compared to control (P&lt;0.01). Together, these results demonstrate that APN resistance develops 2 weeks after MI, a critical period when the transition from adaptive to pathological remodeling occurs. APN resistance renders a potent endogenous cardioprotective molecule ineffective, thus facilitating HF progression. Interventions restoring cardiac APN response may be a novel approach against post-MI HF development.

Expression system for production of bioactive compounds, recombinant human adiponectin, in the silk glands of transgenic silkworms

Adiponectin is an adipocyte hormone involved in glucose and lipid metabolism. The aim of this study was to develop a human adiponectin expression system in transgenic silkworm using a human adiponectin expression vector. The silk gland of the silkworm is a highly specialized organ that has the wonderful ability to synthesize and secrete silk protein. To express human adiponectin in the silk gland of transgenic silkworm, targeting vectors pB-A3-adiponectin-IRES-RFP and pB-Ser1-adiponectin-IRES-RFP were constructed and then introduced into the silkworm pupa. The transgenic silkworms were verified by PCR and then generated. The level of adiponectin in the transgenic silkworm was 6-10 ng/50 mg of freeze-dried powder, and western blotting using an antibody against human adiponectin demonstrated a specific band with a molecular weight of 30 kDa in the silkworm. These results showed that human adiponectin introduced into the silkworm genome was expressed successfully on a large-scale.

Emerging Roles for Vasoactive Peptides in Diagnostic and Therapeutic Strategies Against Atherosclerotic Cardiovascular Diseases

Coronary artery disease (CAD) arising from atherosclerosis remains the most common cause of death and morbidity worldwide, although its risk factors, such as hypertension, dyslipidemia, and diabetes, have been individually treated with increasingly improved outcomes. Therefore, it is important to develop diagnostic and therapeutic windows for CAD. Many classical vasoactive hormones, inflammatory cytokines, and oxidative products have been implicated as potential biomarkers. Our recent studies have shown that high levels of the pro-atherogenic vasoactive agents, serotonin and urotensin II, which are potent vasoconstrictors, can be used as biomarkers for CAD. In subsequent trials, we unraveled anti- and pro-atherogenic roles for more recently identified peptides. Anti-atherogenic peptides include the adipocytokine adiponectin, the neuronal growth factor heregulin-β₁ (neuregulin-1 type I), the incretin hormone, glucagon-like peptide-1 (GLP-1), and a peptide recently identified by an in silico approach, salusin-α. Atherogenic roles have been demonstrated by cellular, animal, and clinical experiments, which indicate that human adiponectin, heregulin-β₁, GLP-1, and salusin-α attenuate the development of atherosclerotic lesions by suppressing macrophage foam cell formation via down-regulation of acyl-CoA:cholesterol acyltransferase-1. Circulating levels of these peptides in the blood are markedly decreased in CAD patients compared with those in non-CAD patients. Receiver operating characteristic curve analyses have shown that salusin-α is the most useful biomarker for detecting CAD among the four peptides examined. Therefore, salusin-α, alone or in various combinations with heregulin-β₁, adiponectin, and/or GLP-1, is a candidate biomarker for predicting CAD. Further, anti-atherogenic peptides could potentially serve as useful therapeutic targets for atherosclerotic cardiovascular diseases.

Association of the + 45T > G adiponectin gene polymorphism with insulin resistance in non-diabetic Saudi women

BackgroundThe human adiponectin gene variations are associated with obesity, insulin resistance, and diabetes. However, these associations have not been fully examined in a non-diabetic population in Saudi Arabia. We aimed to investigate the association of 45T>G single nucleotide polymorphism (SNP) in the adiponectin gene with total adiponectin levels, insulin resistance (IR), fasting blood glucose (FBG) and other markers of obesity in non-diabetic Saudi females. MethodsOne hundred non diabetic Saudi females were enrolled in this study. They were further divided according to their body mass index (BMI) into two groups. Group I, 46 non diabetic subjects with normal body weight and group II, 54 overweight and obese females. Adiponectin 45T/G polymorphism was detected by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). Serum adiponectin was measured by ELISA. ResultsObese women exhibited a higher distribution of TG/GG genotype compared with non-obese women. SNP +45T>G genotypes were associated with higher FBG, insulin levels and HOMA–IR with lower total adiponectin levels in obese Saudi women. Otherwise the all estimated variables revealed non-significant differences among the non-obese genotypes. The observed differences in insulin resistance markers were very significant among women with a higher body weight but not among normal body weight women, thus suggesting that SNP +45T>G effects on insulin sensitivity may depend upon body weight and body fat status. ConclusionSNP +45T>G of adiponectin gene has a significant role in the development of insulin resistance in Saudi women possibly through an interaction with increase body weight and hypoadiponectinemia.

Drosophila Adiponectin Receptor in Insulin Producing Cells Regulates Glucose and Lipid Metabolism by Controlling Insulin Secretion

Adipokines secreted from adipose tissue are key regulators of metabolism in animals. Adiponectin, one of the adipokines, modulates pancreatic beta cell function to maintain energy homeostasis. Recently, significant conservation between Drosophila melanogaster and mammalian metabolism has been discovered. Drosophila insulin like peptides (Dilps) regulate energy metabolism similarly to mammalian insulin. However, in Drosophila, the regulatory mechanism of insulin producing cells (IPCs) by adipokine signaling is largely unknown. Here, we describe the discovery of the Drosophila adiponectin receptor and its function in IPCs. Drosophila adiponectin receptor (dAdipoR) has high homology with the human adiponectin receptor 1. The dAdipoR antibody staining revealed that dAdipoR was expressed in IPCs of larval and adult brains. IPC- specific dAdipoR inhibition (Dilp2>dAdipoR-Ri) showed the increased sugar level in the hemolymph and the elevated triglyceride level in whole body. Dilps mRNA levels in the Dilp2>dAdipoR-Ri flies were similar with those of controls. However, in the Dilp2>dAdipoR-Ri flies, Dilp2 protein was accumulated in IPCs, the level of circulating Dilp2 was decreased, and insulin signaling was reduced in the fat body. In ex vivo fly brain culture with the human adiponectin, Dilp2 was secreted from IPCs. These results indicate that adiponectin receptor in insulin producing cells regulates insulin secretion and controls glucose and lipid metabolism in Drosophila melanogaster. This study demonstrates a new adipokine signaling in Drosophila and provides insights for the mammalian adiponectin receptor function in pancreatic beta cells, which could be useful for therapeutic application.

FRI0010 Effects of leptin and adiponectin on proliferation, activation and th17 differentiation were significantly increased in cd4+ t cells from rheumatoid arthritis patients

BackgroundRecent in vitro and in vivo studies suggest that leptin and adiponectin are involved in the development of the inflammatory profile of rheumatoid arthritis (RA) patients. Previous findings by our...

SAT0047 The origin and biological activities of classical adipokines in rheumatoid joint

BackgroundClassical adipokines, leptin and adiponectin, are thought to originate principally from white adipose tissue. Although both of them have been suggested to participate in pathogenesis of rheumatoid arthritis (RA), their...