RESUMO
We previously reported that prostaglandin (PG)D2 and its isosteric analog, 11-deoxy-11-methylene-PGD2 (11d-11m-PGD2), promote adipogenesis in 3T3-L1 cells during the maturation phase. Focusing on the differentiation phase, although both PGs inhibited adipogenesis, this effect was canceled out by PGI2 and PGJ2 derivatives. Thus, PGD2 and 11d-11m-PGD2 play different roles during the phases, but do not affect PGI2- and PGJ2-derivative-induced adipogenesis.
Assuntos
Adipogenia , Prostaglandina D2 , Células 3T3-L1 , Animais , Diferenciação Celular , Camundongos , Prostaglandina D2/farmacologiaRESUMO
Arachidonic acid (AA) and the related prostanoids exert complex effects on the adipocyte differentiation depending on the culture conditions and life stages. Here, we investigated the effect of the pretreatment of cultured 3T3-L1 preadipocytes with exogenous AA during the differentiation phase without 3-isobutyl-1-methylxanthine (IBMX), a cAMP-elevating agent, on the storage of fats after the maturation phase. This pretreatment with AA stimulated appreciably adipogenesis after the maturation phase as evident with the up-regulated gene expression of adipogenic markers. The stimulatory effect of the pretreatment with AA was attenuated by the co-incubation with each of cyclooxygenase (COX) inhibitors. Among exogenous prostanoids and related compounds, the pretreatment with MRE-269, a selective agonist of the IP receptor for prostaglandin (PG) I2, strikingly stimulated the storage of fats in adipocytes. The gene expression analysis of arachidonate COX pathway revealed that the transcript levels of inducible COX-2, membrane-bound PGE synthase-1, and PGF synthase declined more greatly in cultured preadipocytes treated with AA. By contrast, the expression levels of COX-1, cytosolic PGE synthase, and PGI synthase remained constitutive. The treatment of cultured preadipocytes with AA resulted in the decreased synthesis of PGE2 and PGF2α serving as anti-adipogenic PGs although the biosynthesis of pro-adipogenic PGI2 was up-regulated during the differentiation phase. Moreover, the gene expression levels of EP4 and FP, the respective prostanoid receptors for PGE2 and PGF2α, were gradually suppressed by the supplementation with AA, whereas that of IP for PGI2 remained relatively constant. Collectively, these results suggest the predominant role of endogenous PGI2 in the stimulatory effect of the pretreatment of cultured preadipoccytes with AA during the differentiation phase without IBMX on adipogenesis after the maturation phase.
Assuntos
Adipócitos/efeitos dos fármacos , Adipogenia/efeitos dos fármacos , Ácido Araquidônico/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Células-Tronco Mesenquimais/efeitos dos fármacos , 1-Metil-3-Isobutilxantina , Células 3T3-L1 , 6-Cetoprostaglandina F1 alfa/metabolismo , Acetatos/farmacologia , Adipócitos/citologia , Adipócitos/metabolismo , Adipogenia/genética , Animais , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , AMP Cíclico/metabolismo , Ciclo-Oxigenase 1/genética , Ciclo-Oxigenase 1/metabolismo , Ciclo-Oxigenase 2/genética , Ciclo-Oxigenase 2/metabolismo , Inibidores de Ciclo-Oxigenase/farmacologia , Dinoprosta/metabolismo , Dinoprostona/metabolismo , Humanos , Hidroxiprostaglandina Desidrogenases/genética , Hidroxiprostaglandina Desidrogenases/metabolismo , Proteínas de Membrana/antagonistas & inibidores , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Camundongos , Prostaglandina-E Sintases/genética , Prostaglandina-E Sintases/metabolismo , Pirazinas/farmacologia , Receptores de Prostaglandina/antagonistas & inibidores , Receptores de Prostaglandina/genética , Receptores de Prostaglandina/metabolismo , Receptores de Prostaglandina E Subtipo EP4/antagonistas & inibidores , Receptores de Prostaglandina E Subtipo EP4/genética , Receptores de Prostaglandina E Subtipo EP4/metabolismo , Transdução de Sinais , Triglicerídeos/metabolismoRESUMO
A linoleic acid (LA) metabolite arachidonic acid (AA) added to 3T3-L1 cells is reported to suppress adipogenesis. The purpose of the present study aimed to clarify the effects of AA added during the differentiation phase, including adipogenesis, the types of prostaglandins (PG)s produced, and the crosstalk between AA and the PGs produced. Adipogenesis was inhibited by AA added, while LA did not. When AA was added, increased PGE2 and PGF2α production, unchanged Δ12-PGJ2 production, and reduced PGI2 production were observed. Since the decreased PGI2 production was reflected in decreased CCAAT/enhancer-binding protein-ß (C/EBPß) and C/EBPδ expression, we expected that the coexistence of PGI2 with AA would suppress the anti-adipogenic effects of AA. However, the coexistence of PGI2 with AA did not attenuate the anti-adipogenic effects of AA. In addition, the results were similar when Δ12-PGJ2 coexisted with AA. Taken together, these results indicated that the metabolism of ingested LA to AA is necessary to inhibit adipogenesis and that exposure of AA to adipocytes during only the differentiation phase is sufficient. As further mechanisms for suppressing adipogenesis, AA was found not only to increase PGE2 and PGF2α and decrease PGI2 production but also to abrogate the pro-adipogenic effects of PGI2 and Δ12-PGJ2.