Kegg Pathway: Adipocytokine signaling pathway

Int J Obes (Lond). 2008 Jul 22;
Kim K, Perroud B, Espinal G, Kachinskas D, Austrheim-Smith I, Wolfe BM, Warden CH

Context:Gastric bypass surgery is the most commonly performed bariatric surgical procedure in the United States. Variable weight loss following this relatively standardized intervention has been reported. To date, a method for reliable profiling of patients who will successfully sustain weight loss for the long term has not been established. In addition, the mechanisms of action in accomplishing major weight loss as well as the explanation for the variable weight loss have not been established.Objective:To examine whether gene expression in perioperative omental adipose is associated with gastric bypass-induced weight loss.Design:Cross-sectional study of gene expression in perisurgical omental adipose tissues taken/available at the time of operation and total excess weight loss (EWL).Subjects:Fifteen overweight individuals who underwent Roux-en-Y gastric bypass (RYGB) surgery at the University of California Davis Medical Center (BMI: 40.6-72.8 kg/m(2)).Measurements:Body weight before and following weight stabilization 18-42 months after surgery. Perioperative omental adipose RNA isolated from 15 subjects was hybridized to Affymetrix HG-U133A chips for 22 283 transcript expression measurements.Results:Downstream analysis identified a set of genes whose expression was significantly correlated with RYGB-induced weight loss. The significant individual genes include acyl-coenzyme A oxidase 1 (ACOX1), phosphodiesterase 3A cGMP-inhibited (PDE3A) and protein kinase, AMP-activated, beta 1 non-catalytic subunit (PRKAB1). Specifically, ACOX1 plays a role in fatty acid metabolism. PDE3A is involved in purine metabolism and hormone-stimulated lipolysis. PRKAB1 is involved in Adipocytokine signaling pathway. Gene network analysis revealed that pathways for glycerolipid metabolism, breast cancer and apoptosis were significantly correlated with long-term weight loss.Conclusion:This study demonstrates that RNA expression profiles from perioperative adipose tissue are associated with weight loss outcome following RYGB surgery. Our data suggest that EWL could be predicted from preoperative samples, which would allow for informed decisions about whether or not to proceed to surgery.International Journal of Obesity advance online publication, 22 July 2008; doi:10.1038/ijo.2008.106.

J Recept Signal Transduct Res. 2008; 28(3): 185-243
Genini S, Malinverni R, Delputte PL, Fiorentini S, Stella A, Botti S, Nauwynck HJ, Giuffra E

Sialoadhesin (Sn) is the prototypic member of the Siglecs, a family of receptors mainly involved in cell-cell interactions. For several Siglecs, but not for Sn, intracellular signaling functions have been described. Because antibody-mediated cross-linking of surface transmembrane proteins is a powerful technique to investigate cell-molecular events, Sn expressed on porcine alveolar macrophages (PAM) was cross-linked with the antibody 41D3, and the expression profiles were compared with mock-treated macrophages by microarray analysis. Gene ontology analysis of 479 differentially expressed transcripts identified gene categories related to membrane localization, signal transduction, receptor and communication activities. Analyses of the human KEGG pathway database identified MAP kinase signaling, regulation of actin cytoskeleton, Adipocytokine signaling, and wnt signaling as significantly altered pathways, supporting a role for Sn as intracellular signaling molecule. Real-time PCR of a subset of modulated genes confirmed these results and highlighted the reliability of a short-term cross-linking treatment for transcriptomic analysis of receptor functions.

J Pharmacol Sci. 2008 May; 107(1): 41-8
Tomimoto S, Ojika T, Shintani N, Hashimoto H, Hamagami K, Ikeda K, Nakata M, Yada T, Sakurai Y, Shimada T, Morita Y, Ishida C, Baba A

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide implicated in several metabolic functions, including insulin secretion and sympathoadrenal activation. To clarify the roles of PACAP in maintenance of whole-body glucose and lipid homeostasis, the impact of the deletion of PACAP on glucose homeostasis, body weight, and adipose tissue mass was examined by comparing mice lacking the Adcyap1 gene encoding PACAP (Adcyap1(-/-)) with wild-type littermate controls. Adcyap1(-/-) mice showed significant hypoinsulinemia, although being normoglycemic, and lower body weight as well as reduced food intake. They also showed greatly reduced white adipose tissue mass, in which the mRNA expression of adipocyte fatty acid-binding protein (aP2), a marker of adipocyte differentiation, was decreased. Glucose and insulin tolerance tests revealed increased insulin sensitivity in Adcyap1(-/-) mice. In accordance with these observations, plasma levels of resistin, an Adipocytokine implicated in insulin resistance, were decreased in Adcyap1(-/-) mice. After a high-fat dietary challenge for six weeks, Adcyap1(-/-) mice still showed lower body weights and increased insulin sensitivity. These results indicate the crucial roles of PACAP in energy metabolism, including lipid metabolism, and in the regulation of body weight, raising the possibility that the PACAP-signaling pathway that favors energy storage could be a therapeutic target for obesity.

J Cell Mol Med. 2008 Apr 9;
Di Simone N, Di Nicuolo F, Marzioni D, Castellucci M, Sanguinetti M, D'Ippolito S, Caruso A

The Adipocytokine resistin impairs glucose tolerance and insulin sensitivity. Here, we examine the effect of resistin on glucose uptake in human trophoblast cells and we demonstrate that transplacental glucose transport is mediated by glucose transporter (GLUT)-1. Furthermore, we evaluate the type of signal transduction induced by resistin in GLUT-1 regulation. BeWo choriocarcinoma cells and primary cytotrophoblast cells were cultured with increasing resistin concentrations for 24 hours. The main outcome measures include glucose transport assay using [(3)H]-2-deoxy glucose, GLUT-1 protein expression by Western Blot analysis and GLUT-1 mRNA detection by quantitative real-time RT-PCR. Quantitative determination of phospho(p)-ERK1/2 in cell lysates was performed by an Enzyme Immunometric Assay and Western Blot analysis. Our data demonstrate a direct effect of resistin on normal cytotrophoblastic and on BeWo cells: resistin modulates glucose uptake, GLUT-1 messenger ribonucleic acid (mRNA) and protein expression in placental cells. We suggest that ERK1/2 phosphorylation is involved in the GLUT-1 regulation induced by resistin. In conclusion, resistin causes activation of both the ERK1 and 2 pathway in trophoblast cells. ERK1 and 2 activation stimulated GLUT-1 synthesis and resulted in increase of placental glucose uptake. High resistin levels (50-100 ng/ml) seem able to affect glucose-uptake, presumably by decreasing the cell surface glucose transporter.

Am J Physiol Endocrinol Metab. 2008 May; 294(5): E898-909
Takahashi K, Yamaguchi S, Shimoyama T, Seki H, Miyokawa K, Katsuta H, Tanaka T, Yoshimoto K, Ohno H, Nagamatsu S, Ishida H

Obese conditions increase the expression of Adipocytokine monocyte chemoattractant protein-1 (MCP-1) in adipose tissue as well as MCP-1 plasma levels. To investigate the mechanism behind increased MCP-1, we used a model in which 3T3-L1 adipocytes were artificially hypertrophied by preloading with palmitate in vitro. As observed in obesity, under our model conditions, palmitate-preloaded cells showed significantly increased oxidative stress and increased MCP-1 expression relative to control cells. This increased MCP-1 expression was enhanced by adding exogenous tumor necrosis factor-alpha (TNF-alpha; 17.8-fold vs. control cells, P < 0.01) rather than interleukin-1beta (IL-1beta; 2.6-fold vs. control cells, P < 0.01). However, endogenous TNF-alpha and IL-1beta release was not affected in hypertrophied cells, suggesting that these endogenous cytokines do not mediate hypertrophy-induced increase in MCP-1. MCP-1 secretion from hypertrophied cells was significantly decreased by treatment with antioxidant N-acetyl-cysteine, JNK inhibitors SP600125 and JIP-1 peptide, and IkappaB phosphorylation inhibitors BAY 11-7085 and BMS-345541 (P < 0.01). MCP-1 secretion was not affected by peroxisome proliferator-activated receptor-gamma (PPARgamma) antagonists assayed. Adiponectin, another Adipocytokine studied in parallel, also showed increased release in hypertrophy relative to control cells. But in contrast to MCP-1, adiponectin release was significantly suppressed by both exogenous TNF-alpha and IL-1beta as well as by PPARgamma antagonists bisphenol A diglycidyl ether and T0070907 (P < 0.01). JNK inhibitors and IkappaB phosphorylation inhibitors showed no significant effect on adiponectin. We conclude that adipocyte hypertrophy through palmitate loading causes oxidative stress, which in turn increases MCP-1 expression and secretion through JNK and IkappaB signaling. In contrast, the parallel increase in adiponectin expression appears to be related to the PPARgamma ligand properties of palmitate.

J Mol Cell Cardiol. 2008 Feb; 44(2): 388-94
Bobbert P, Antoniak S, Schultheiss HP, Rauch U

Adiponectin (APN), a recently discovered Adipocytokine, is present in human serum in a full length (fAPN) and a globular form (gAPN). gAPN is a proteolytic cleavage product of fAPN and seems to show independent biological activities compared to the properties of fAPN. The influence of gAPN and fAPN on procoagulability of cells is still unknown. This study examined the effect of gAPN and fAPN on the expression of tissue factor (TF), the initiator of the extrinsic coagulation system, in human umbilical vein endothelial cells (HUVECs). TF activity was measured by a chromogenic assay, TF mRNA by real-time PCR and TF protein by western blot. We found TF activity to be increased after activation by gAPN (3 microg/mL) compared to a non-stimulated control (169.0+/-19.23 U versus 501.9+/-38.95 U, p<0.001). Furthermore, TF mRNA and TF protein was increased dose-dependently after gAPN stimulation. The gAPN-induced rise of TF activity and TF mRNA was significantly reduced by inhibition of the MAP kinases ERK1/2, p38 and JNK. Contrary to gAPN, stimulation with fAPN did not lead to these procoagulant effects. In conclusion, gAPN increased TF transcription, expression and activity in HUVECs. Therefore, our data support the theory that gAPN but not fAPN supports the cellular procoagulability via TF upregulation.

Biochem Biophys Res Commun. 2007 Dec 7; 364(1): 33-9
Nozaki M, Fukuhara A, Segawa K, Okuno Y, Abe M, Hosogai N, Matsuda M, Komuro R, Shimomura I

Obesity is associated with infiltration of macrophages into adipose tissue, and macrophages are an important source of nitric oxide (NO). Dysregulated production of fat-derived secretory factor, Adipocytokine, leads to obesity-linked metabolic disorders. However, it has not been fully determined whether NO might have direct effects on Adipocytokine expressions. Here, we show that NO donor treatment downregulated gene expression and secretion of adiponectin, and upregulated mRNA levels of PAI-1 and IL-6. NO donor reduced promoter activity of adiponectin through PPARgamma responsive element. Moreover, NO donor activated JNK and