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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adipocyte cell proliferation is an important process in body fat mass development in obesity. Adiponectin or Acrp30 is an adipocytokine exclusively expressed and secreted by adipose tissue that regulates lipid and glucose metabolism and plays a key role in body weight regulation and homeostasis. Adiponectin mRNA expression in adipose tissue and plasma level of adiponectin are decreased in obesity and type 2 diabetes. In obese rodents, the selective CB(1) receptor antagonist rimonabant reduces food intake and body weight and improves lipid and glucose parameters. We have reported previously that rimonabant stimulated adiponectin mRNA expression in adipose tissue of obese fa/fa rats, by a direct effect on adipocytes. We report here that rimonabant (10-400 nM) inhibits cell proliferation of cultured mouse 3T3 F442A preadipocytes in a concentration-dependent manner. In parallel to this inhibitory effect on preadipocyte cell proliferation, rimonabant (25-100 nM) stimulates mRNA expression and protein levels of two late markers of adipocyte differentiation (adiponectin and glyceraldehyde-3-phosphate dehydrogenase) with a maximal effect at 100 nM, without inducing the accumulation of lipid droplets. Furthermore, treatment of mouse 3T3 F442A preadipocytes with rimonabant (100 nM) inhibits basal and serum-induced p42/44 mitogen-activated protein (MAP) kinase activity. These results suggest that inhibition of MAP kinase activity by rimonabant may be one of mechanisms involved in the inhibition of 3T3 F442A preadipocyte cell proliferation and stimulation of adiponectin and GAPDH expression. The inhibition of preadipocyte cell proliferation and the induction of adipocyte late "maturation" may participate in rimonabant-induced antiobesity effects, particularly the reduction of body fat mass.
Mol Pharmacol 2006 Feb
PMID:The cannabinoid CB1 receptor antagonist rimonabant (SR141716) inhibits cell proliferation and increases markers of adipocyte maturation in cultured mouse 3T3 F442A preadipocytes. 1628 21

Adiponectin has been shown to regulate glucose and fatty acid uptake and metabolism in skeletal muscle. Here we investigated the role of the recently cloned adiponectin receptor (AdipoR) isoforms in mediating effects of both globular (gAd) and full-length (fAd) adiponectin, and their regulation by hyperglycemia (25 mM, 20 h) and hyperinsulinemia (100 nM, 20 h). We used L6 rat skeletal muscle cells, which were found to express both AdipoR1 and AdipoR2 mRNA in a ratio of over 6:1 respectively. Hyperglycemia and hyperinsulinemia both decreased AdipoR1 receptor expression by approximately 50%, while the latter induced an increase of approximately threefold in AdipoR2 expression. The ability of gAd to increase GLUT4 myc translocation, glucose uptake, fatty acid uptake and oxidation, as well as AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) phosphorylation, was decreased by both hyperglycemia and hyperinsulinemia. Interestingly, hyperinsulinemia induced the ability of fAd to elicit fatty acid uptake and enhanced fatty acid oxidation in response to fAd. In summary, our results suggest that both hyperglycemia and hyperinsulinemia cause gAd resistance in rat skeletal muscle cells. However, hyperinsulinemia induces a switch toward increased fAd sensitivity in these cells.
J Mol Endocrinol 2005 Dec
PMID:Hyperglycemia- and hyperinsulinemia-induced alteration of adiponectin receptor expression and adiponectin effects in L6 myoblasts. 1632 33

The expression of 76 sequences, previously isolated as differentially expressed in visceral white adipose tissue (WAT) of female rats, fed with a high-fat diet for 11 days (Lopez et al., Biochem Biophys Res Comm 318: 234-239, 2004), was analyzed in epidydimal WAT of male rats after a feeding period of 65 days with the same diet, using microarray technology. After Northern blot validation of the results, only three genes appeared upregulated (caveolin-2, the alpha-1 chain of haemoglobin and rat mammary tumor-7) and two downregulated (adiponectin and dystroglycan). We have also analyzed caveolin-1 gene expression and found that follows the opposite pattern of caveolin-2, indicating that they are inversely regulated. Our results suggest that if feeding with a high-fat diet is prolonged, many of the initial changes in gene expression, probably aimed to consume the energy surplus and prevent excessive fat deposition, are not maintained, and adaptation to an increased lipid storage is developed.
Mol Cell Biochem 2005 Jul
PMID:High-fat feeding period affects gene expression in rat white adipose tissue. 1633 90

We have identified Kruppel-like factor 7 (KLF7) as a new candidate for conferring susceptibility to type 2 diabetes. To ascertain the possible involvement of KLF7 in the pathogenesis of type 2 diabetes, we examined the functional roles of KLF7 in various types of cells. In human adipocytes overexpressing KLF7, the expression of adiponectin and leptin was decreased compared with that in control cells, whereas expression of IL-6 was increased. In the insulin-secreting cell line (HIT-T15 cells), the expression and glucose-induced secretion of insulin were significantly suppressed in KLF7-overexpressed cells compared with control cells, accompanied by the reduction in the expression of glucose transporter 2, sulfonylurea receptor 1, Kir6.2, and pancreatic-duodenal homeobox factor 1. We also found that the overexpression of KLF7 resulted in the decrease of hexokinase 2 expression in smooth muscle cells, and of glucose transporter 2 expression in the HepG2 cells. These results suggest that KLF7 may contribute to the pathogenesis of type 2 diabetes through an impairment of insulin biosynthesis and secretion in pancreatic beta-cells and a reduction of insulin sensitivity in peripheral tissues. Therefore, we suggest that KLF7 plays an important role in the pathogenesis of type 2 diabetes, and may be a useful target for new drugs to aid in the prevention and treatment of this disease.
Mol Endocrinol 2006 Apr
PMID:Overexpression of Kruppel-like factor 7 regulates adipocytokine gene expressions in human adipocytes and inhibits glucose-induced insulin secretion in pancreatic beta-cell line. 1633 72

Adiponectin, an adipose-derived plasma protein, has been well established to be an important biomarker for metabolic syndrome and its complications after exhausted studies in humans. Animal and cell culture experiments also support most claims from human observations of its roles in the metabolic syndrome. Reproducible results of human genetic studies of diverse ethnic origin and by different investigators may provide the evidence for its causative roles in the pathogenesis of the metabolic syndrome and further insight into the genetic constitutions of the metabolic syndrome. Some of the common polymorphisms in the promoter region, exon and intron 2, and the rare nonsynonymous mutations in exon 3 of the human adiponectin gene were repeatedly shown in many studies from many different ethnic populations to associate with the phenotypes related to body weight, glucose metabolism, insulin sensitivity, and risk of type 2 diabetes mellitus and coronary artery disease. The association of adiponectin genetic variations with dyslipidemia and blood pressure was less explored. The common polymorphisms and rare mutations of the human adiponectin gene itself were demonstrated to associate with differential expression of adiponectin at the plasma protein level and mRNA level in adipose tissue. The PPARgamma2 Pro12Ala variants were also shown to influence insulin sensitivity in interaction with adiponectin genotype or to influence plasma adiponectin levels. However, the results were not consistent. Three genome-wide scans for the loci that regulate plasma adiponectin concentration suggest further exploration on chromosomes 5, 9, 14, 15, and 18 is required. These human genetic studies on adiponectin and the metabolic syndrome strongly suggest that adiponectin is one of the causative factors in its pathogenesis and provide significant insights into the genetic makeup of the metabolic syndrome. Extension from these studies may accelerate the discovery of new molecular targets for future therapeutic interventions.
J Mol Med (Berl) 2006 Feb
PMID:Human genetics of adiponectin in the metabolic syndrome. 1638 53

The CCAAT/enhancer-binding protein (C/EBP) family of transcriptional regulators is critically important for the activation of adipogenic genes during differentiation. The C/EBPbeta and delta isoforms are rapidly induced upon adipocyte differentiation and are responsible for activating the adipogenic regulators C/EBPalpha and peroxisome proliferator activated receptor (PPAR)gamma2, which together activate the majority of genes expressed in differentiating adipocytes. However, mitosis is required following the induction of adipogenesis, and the activation of C/EBPalpha and PPARgamma2 gene expression is delayed until cell division is underway. Previous studies have used electromobility shift assays to suggest that this delay is due, at least in part, to a delay between the induction of C/EBPbeta protein levels and the acquisition of DNA binding capacity by C/EBPbeta. Here we used in vivo chromatin immunoprecipitation analysis of the C/EBPalpha, PPARgamma2, resistin, adiponectin, and leptin promoters to examine the kinetics of C/EBP protein binding to adipogenic genes in differentiating cells. In contrast to prior studies, we determined that C/EBPbeta and delta were bound to endogenous regulatory sequences controlling the expression of these genes within 1-4 h of adipogenic induction. These results indicated that C/EBPbeta and delta bind not only to genes that are induced early in the adipogenic process but also to genes that are induced much later during differentiation, without a delay between induction of C/EBP protein levels and DNA binding by these proteins. We also showed that each of the genes examined undergoes a transition in vivo from early occupancy by C/EBPbeta and delta to occupancy by C/EBPalpha at times that correlate with the induction of C/EBPalpha protein levels, demonstrating the generality of the transition during adipogenesis and indicating that the binding of specific C/EBP isoforms does not correlate with timing of expression from each gene. We have concluded that C/EBP family members bind to adipogenic genes in vivo in a manner that follows the induction of C/EBP protein synthesis.
J Mol Endocrinol 2006 Feb
PMID:Temporal recruitment of CCAAT/enhancer-binding proteins to early and late adipogenic promoters in vivo. 1646 34

Adiponectin is a secreted, multimeric protein with insulin-sensitizing, antiatherogenic, and antiinflammatory properties. Serum adiponectin consists of trimer, hexamer, and larger high-molecular-weight (HMW) multimers, and these HMW multimers appear to be the more bioactive forms. Multimer composition of adiponectin appears to be regulated; however, the molecular mechanisms involved are unknown. We hypothesize that regulation of adiponectin multimerization and secretion occurs via changes in posttranslational modifications (PTMs). Although a structural role for intertrimer disulfide bonds in the formation of hexamers and HMW multimers is established, the role of other PTMs is unknown. PTMs identified in murine and bovine adiponectin include hydroxylation of multiple conserved proline and lysine residues and glycosylation of hydroxylysines. By mass spectrometry, we confirmed the presence of these PTMs in human adiponectin and identified three additional hydroxylations on Pro71, Pro76, and Pro95. We also investigated the role of the five modified lysines in multimer formation and secretion of recombinant human adiponectin expressed in mammalian cell lines. Mutation of modified lysines in the collagenous domain prevented formation of HMW multimers, whereas a pharmacological inhibitor of prolyl- and lysyl-hydroxylases, 2,2'-dipyridyl, inhibited formation of hexamers and HMW multimers. Bacterially expressed human adiponectin displayed a complete lack of differentially modified isoforms and failed to form bona fide trimers and larger multimers. Finally, glucose-induced increases in HMW multimer production from human adipose explants correlated with changes in the two-dimensional electrophoresis profile of adiponectin isoforms. Collectively, these data suggest that adiponectin multimer composition is affected by changes in PTM in response to physiological factors.
Mol Endocrinol 2006 Jul
PMID:Adiponectin multimerization is dependent on conserved lysines in the collagenous domain: evidence for regulation of multimerization by alterations in posttranslational modifications. 1649 31

Adiponectin is an adipocyte-derived circulating peptide that plays an important role in adipose tissue metabolism, insulin sensitivity and cardiovascular disease. The adrenal gland, by secreting glucorticoid and mineralocorticoid hormones, intervenes in cardiovascular and glucose metabolism regulation and is surrounded by adipose tissue. Hence, we investigated the hypothesis that adiponectin receptor types 1 and 2 (adipo-R1 and adipo-R2) are expressed in the human adrenal gland and in adrenocortical zona glomerulosa cell-derived aldosterone-producing adenoma (APA) tissue. We used real-time reverse transcription-polymerase chain reaction to demonstrate the mRNA of adipo-R1 and adipo-R2 in 10 histologically normal human adrenal cortexes that were obtained from patients with renal cancer undergoing nephrectomy with ipsilateral adrenalectomy and in 10 APAs. Melting curve analysis and sequencing were used to confirm the specificity of the amplicons obtained. Results consistently showed the expression of specific mRNAs of adiponectin receptors in all histologically normal human adrenal cortexes and APAs. This novel finding suggests that adiponectin could play a regulatory role in adrenocortical function and growth in humans.
Int J Mol Med 2006 Jun
PMID:Adiponectin receptor expression in the human adrenal cortex and aldosterone-producing adenomas. 1668 4

Adiponectin was revealed to have anti-atherogenic and anti-inflammatory properties and has been recently found to stimulate angiogenesis in vivo and in vitro. However, the role of adiponectin in endothelial differentiation remains unclear. The objective of this study was to investigate whether adiponectin can promote peripheral CD14(+) monocytes differentiation into endothelial cells (ECs). Human peripheral blood CD14(+) monocytes were cultured with or without adiponectin (10 microg/ml) for 10 days. Adiponectin significantly promoted EC morphology formation from CD14(+) monocytes. By flow cytometery analysis, cells treated with adiponection substantially increased mean fluorescence intensity of vascular endothelial growth factor receptor-2 (VEGFR-2) and endothelial nitric oxide synthase (eNOS), two specific endothelial markers, by 49.2 % and 53.9 %, respectively, as compared to control cells. By real time PCR analysis, the mRNA level of eNOS in adiponectin-treated cells was also increased by 31.9 % of that of the control cells. However, the mRNA levels of calponin and SMMHC, two specific SMC markers, in adiponectin-treated cells were decreased by 81.1 % and 79.7 % of that of the control cells, respectively. These data demonstrated that adiponectin could promote endothelial differentiation from peripheral blood CD14(+) monocytes by morphology change, upregulation of EC markers and downregulation of SMC markers. Adiponectin-promoted EC differentiation may contribute to vascular healing and angiogenesis.
J Cell Mol Med
PMID:Adiponectin promotes endothelial cell differentiation from human peripheral CD14+ monocytes in vitro. 1679 11

The orphan receptor small heterodimer partner (SHP; NROB2) is a transcriptional repressor that inhibits nuclear receptor signaling in diverse metabolic pathways. Here, we report that SHP(-/-) mice exhibited hypoinsulinemia with age, which was associated with increased peripheral insulin sensitivity and increased response of isolated islets to glucose stimulation, yet maintain normal levels of blood glucose. Deficiency in SHP function resulted in up-regulation of glucose transporter 4 mRNA and glucose uptake in muscles, and overexpression of SHP in C2C12 cells inhibited both basal and peroxisomal proliferator-activated receptor gamma (PPARgamma) coactivator-1alpha-stimulated glucose transporter 4 expression and glucose uptake. SHP(-/-) hepatocytes showed markedly decreased basal glucose production in cultures, and SHP(-/-) livers had increased glycogen stores and were more sensitive to insulin inhibition of glucose output, which were concomitant with decreased expression for PPARgamma1, fatty acid translocase, glucose-6-phosphatase, and phosphoenol/pyruvate carboxykinase, and increased mRNAs for glucokinase and pyruvate kinase. In white fat, SHP deficiency resulted in up-regulation of genes involved in insulin sensitizing, including PPARgamma2 and adiponectin. We show that, at the transcriptional level, SHP directly represses adiponectin promoter activity by PPARgamma/liver receptor homolog-1. The results suggest that the increases in insulin sensitivity through multiple signaling pathways in muscle, liver, and fat, with an increase in islet secretory function, represent the complex mechanism whereby SHP deficiency leads to improvement in insulin sensitivity, secretion, and diabetes.
Mol Endocrinol 2006 Nov
PMID:Orphan receptor small heterodimer partner is an important mediator of glucose homeostasis. 1875 80


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