15-deoxy-delta(12-14)-prostaglandin-j2 and Obesity

Obesity is a worldwide health problem that urgently needs to be solved. Leptin is an anti-obesity hormone that activates satiety signals to the brain. Evidence to suggest that leptin resistance is involved in the development of obesity is increasing; however, the molecular mechanisms involved remain unclear. We herein demonstrated that 15-deoxy-Δ(12,14) -prostaglandin J2 (15d-PGJ2 ) was involved in the development of leptin resistance. A treatment with 15d-PGJ2 inhibited the leptin-induced activation of signal transducer and activator of transcription 3 (STAT3) in neuronal cells (SH-SY5Y-Ob-Rb cells). Furthermore, the intracerebroventricular administration of 15d-PGJ2 reversed the inhibitory effects of leptin on food intake in rats. The peroxisome proliferator-activated receptor gamma (PPAR-γ) antagonist, GW9662, slightly reversed the inhibitory effects of 15d-PGJ2 on the leptin-induced activation of STAT3 in neuronal cells. The PPAR-γ agonist, rosiglitazone, also inhibited leptin-induced STAT3 phosphorylation. Therefore, the inhibitory effects of 15d-PGJ2 may be mediated through PPAR-γ. On the other hand, 15d-PGJ2 -induced leptin resistance may not be mediated by endoplasmic reticulum stress or suppressor of cytokine signaling 3. The results of the present study suggest that 15d-PGJ2 is a novel factor for the development of leptin resistance in obesity. Leptin resistance, an insensitivity to the actions of leptin, is involved in the development of obesity. Here, we found 15-deoxy-Δ(12,14) -prostaglandin J2 (15d-PGJ2 ) may be involved in the development of leptin resistance. The present results suggest that the 15d-PGJ2 may be a novel factor for the development of leptin resistance in obesity. 15d-PGJ2 , 15-Deoxy-Δ(12,14) -prostaglandin J2; STAT3, signal tranducer and activator of transcription 3.

Topics: Animals; Cell Line, Tumor; Eating; Humans; Injections, Intraventricular; Leptin; Male; Obesity; Prostaglandin D2; Rats; Rats, Wistar; Receptors, Leptin

Mast cells are one of the major producers of prostaglandins (PGs). The final metabolite of PGs 15-deoxy-delta-12,14-PGJ(2) (15-deoxy-delta PGJ(2)) is the endogenous ligand of the peroxisome proliferator-activated receptor (PPAR) γ. PPARγ modulates adipocyte differentiation; therefore, we attempted to investigate whether PGs derived from mast cells influenced on adipogenesis. We found the increase of mast cell numbers in fat tissue of obese mice fed with a high-fat diet allowed us to speculate contributions of mast cells to adipogenesis. Mast cell-mediated induction of adipogenesis was evaluated by using 3T3 L1 cells. Supernatants obtained from mast cells stimulated with calcium ionophore or the high-glucose condition contained 15-deoxy-delta PGJ(2) and induced adipogenesis of 3T3 L1 cells. Agonistic activity of PGJ(2) from the supernatants on PPARγ was confirmed by a reporter gene assay. Culture medium collected from calcium ionophore-stimulated bone marrow-derived cultured mast cells (BMCMC) activated PPAR-responsive element in NIH3T3 fibroblasts, and the specific inhibitor of PPARγ canceled the activation. Contribution of mast cells to obesity was evaluated by using mast cell-deficient mice fed with a Western diet. Weight gain of mast cell-deficient mice during high-fat feeding was impaired compared with their littermate wild-type mice; on the other hand, transplantation of bone marrow-derived cultured mast cells to mast cell-deficient mice restored the weight gain by intake of a high-fat diet. In this study, we clearly demonstrated that mast cells produced PGs in response to the high-glucose condition and induced adipocyte differentiation and possibly obesity. This is the first study that provides evidence for a novel role of mast cells in adipogenesis via PPARγ activation.

Topics: 3T3-L1 Cells; Adipocytes; Adipogenesis; Adipose Tissue; Animals; Cell Differentiation; Male; Mast Cells; Mice; Mice, Inbred C57BL; Obesity; PPAR gamma; Prostaglandin D2; Real-Time Polymerase Chain Reaction

Leptin is considered a key factor in the regulation of appetite and energy expenditure, but little is known about the control of its synthesis and release. Thiazolidinediones (TZDs) have recently been shown to downregulate leptin expression, and it has been speculated that downregulation of the ob gene occurs through activation of the transcription factor, peroxisome proliferator-activated receptor gamma (PPARgamma). However, there are no studies using an endogenous PPARgamma ligand. We examined the effect of 15-deoxy-delta(12,14) prostaglandin J2 (15d-PGJ2), a putative natural ligand of PPARgamma, on ob gene expression in fully differentiated 3T3-L1 adipocytes and compared its effect with that of two other PPARgamma activators, the TZD troglitazone (Trog) and indomethacin (Indo). 15d-PGJ2, Trog, and Indo all inhibited leptin expression at concentrations at which they activate PPARgamma. The inhibition of leptin expression of PPARgamma activators was surprising, since PPARgamma is known to induce adipogenesis during which the ob gene is expressed. To address the possibility that PPARgamma plays different roles before and after the induction of adipogenesis, we examined the effects of the three PPARgamma ligands on the expression of leptin and the glucose transporter protein GLUT4, both of which are expressed during differentiation of 3T3-L1 preadipocytes to adipocytes. In the absence of PPARgamma ligands, leptin and GLUT4 synthesis increased from day 3 to day 9 or 10 during differentiation. However, in the presence of any of the three PPARgamma ligands, GLUT4 expression was unaffected, while ob gene expression was inhibited. We hypothesize that PPARgamma may be essential for induction of adipocyte differentiation but then needs to be inactivated to allow expression of the ob gene.

Topics: Adipose Tissue; Animals; Anti-Inflammatory Agents, Non-Steroidal; Cells, Cultured; Chromans; DNA-Binding Proteins; Dose-Response Relationship, Drug; Down-Regulation; Glucose Transporter Type 4; Humans; Hypoglycemic Agents; Indomethacin; Leptin; Monosaccharide Transport Proteins; Muscle Proteins; Nuclear Proteins; Obesity; Prostaglandin D2; Proteins; Receptors, Cytoplasmic and Nuclear; RNA, Messenger; Thiazoles; Thiazolidinediones; Transcription Factors; Troglitazone