The pleiotropic effects of the insulin-sensitizing adipokine adiponectin are mediated, at least in part, by two seven-transmembrane domain receptors AdipoR1 and AdipoR2. Recent reports indicate a role for AdipoR-binding proteins, namely APPL1, RACK1 and CK2β, in proximal signal transduction events. Here we demonstrate that endoplasmic reticulum protein 46 (ERp46) interacts specifically with AdipoR1 and provide evidence that ERp46 modulates adiponectin signalling. Co-immunoprecipitation followed by mass spectrometry identified ERp46 as an AdipoR1-, but not AdipoR2-, interacting protein. Analysis of truncated constructs and GST-fusion proteins revealed the interaction was mediated by the cytoplasmic, N-terminal residues (1-70) of AdipoR1. Indirect immunofluorescence microscopy and subcellular fractionation studies demonstrated that ERp46 was present in the ER and the plasma membrane (PM). Transient knockdown of ERp46 increased the levels of AdipoR1, and AdipoR2, at the PM and this correlated with increased adiponectin-stimulated phosphorylation of AMPK. In contrast, adiponectin-stimulated phosphorylation of p38MAPK was reduced following ERp46 knockdown. Collectively these results establish ERp46 as the first AdipoR1-specific interacting protein and suggest a role for ERp46 in adiponectin receptor biology and adiponectin signalling. 相似文献
AbstractNicotinamide adenine dinucleotide phosphate (NADPH) oxidase is upregulated in a variety of tissues in obesity. It is still unclear as to whether NADPH oxidase upregulation in a specific tissue is part of a systemic response. Here we analyzed the expression pattern of NADPH oxidase in vascular, adipose, and kidney tissues in a rat model of diet-induced obesity. After weaning, rats were fed either a normal or high-fat diet for 12 weeks. The high-fat diet resulted in 20% increased body weight. In the aorta, Nox4 expression was increased by three-fold in obese rats. Upregulations of p22phox and p47phox in adipose, and Nox4, p22phox, and p47phox in kidney were observed in obesity. Marked increases in plasma leptin and insulin were observed, with more modest changes in adiponectin in obese rats. The average systolic blood pressure in the obese group was 11 mmHg higher than that of lean rats (P < 0.005). There was a significant correlation between blood pressure and aortic Nox4 expression (P < 0.01). In cultured vascular smooth muscle cells, adiponectin reduced the expression of Nox4 in a protein kinase A-dependent manner. Our results suggest that upregulation of NADPH oxidase in multiple tissues during obesity appears to be a systemic response. At least in vitro, adiponectin may have a protective antioxidant role by suppressing vascular NADPH oxidase expression. The association between NADPH oxidase Nox4 expression in the vasculature and the elevated blood pressure in obesity requires further investigation. 相似文献
In a previous study, retrofractamide A from the fruit of Piper chaba was shown to promote adipogenesis in 3T3-L1 cells. In the present study, retrofractamide A and its derivatives were synthesized, and their adipogenetic effects in 3T3-L1 cells were examined. Among the tested compounds, an amide composed of 9-(3′,4′-methylenedioxyphenyl)-nona-2E,4E,8E-trienoic acid and an n-butyl or n-pentyl amine showed strongest activity. Moreover, the amide with the n-pentyl amine moiety significantly increased the uptake of 2-deoxyglucose into the cells, and also increased the mRNA levels of adiponectin, peroxisome proliferator-activated receptor γ2 (PPARγ2), glucose transporter 4 (GLUT4), fatty acid-binding protein (aP2), and CCAAT/enhancer-binding protein (C/EBP) α and β in a similar manner as the PPARγ agonist troglitazone, although it had less agonistic activity against PPARγ. 相似文献
Context: Metabolic imbalance in renal cell carcinoma (RCC) can lead to abnormal adiponectin levels.
Objective: To evaluate circulating adiponectin as a detection or predictive marker for RCC.
Methods: A comprehensive literature search and meta-analysis was performed on studies reporting circulating adiponectin levels and RCC. The meta-analysis was performed using RevMan.
Results: Seven studies compared the circulating adiponection levels between RCC cases and controls. Adiponectin level was significantly lower in RCC cases compared to controls at pre-diagnosis and pre-operative time-points. RCC stage, grade and subtype did not affect adiponectin levels.
Conclusion: Low circulating adiponectin could be a predictive or risk factor for RCC. 相似文献
Pancreatic beta cell dysfunction is an early and crucial pathogenic factor in the development of type 2 diabetes. Free fatty acids (FFA) and adipokines released from adipose tissues lead to both the development of insulin resistance and beta cell dysfunction. Adiponectin is a novel adipokine with antidiabetic properties. Its circulating concentrations are reduced in subjects with increased visceral adiposity, insulin resistance, or type 2 diabetes. Very recently, the cloning of two adiponectin receptors AdipoR1 and AdipoR2 was reported. AdipoR1 is abundantly expressed in muscle, while AdipoR2 is predominantly expressed in liver. Here we report the marked expression of mRNAs for the adiponectin receptors AdipoR1 and AdipoR2 in human and rat pancreatic beta cells, at levels similar to liver and greater than muscle. Adiponectin receptor expression is increased by beta cell exposure to the unsaturated FFA oleate, and treatment of insulin-producing cells with globular adiponectin induces lipoprotein lipase expression. Regulated adiponectin receptor expression on pancreatic beta cells might be a novel mechanism modulating the effects of circulating adiponectin. 相似文献