Comparison of pro-adipogenic effects between prostaglandin (PG) D2 and its stable, isosteric analogue, 11-deoxy-11-methylene-PGD2, during the maturation phase of cultured adipocytes

Abstract

Prostaglandin (PG) D₂ is relatively unstable and dehydrated non-enzymatically into PGJ₂ derivatives, which are known to serve as pro-adipogenic factors by activating peroxisome proliferator-activated receptor (PPAR) γ, a master regulator of adipogenesis. 11-Deoxy-11-methylene-PGD₂ (11d-11m-PGD₂) is a novel, chemically stable, isosteric analogue of PGD₂ in which the 11-keto group is replaced by an exocyclic methylene. Here we attempted to investigate pro-adipogenic effects of PGD₂ and 11d-11m-PGD₂ and to compare the difference in their ways during the maturation phase of cultured adipocytes. The dose-dependent study showed that 11d-11m-PGD₂ was significantly more potent than natural PGD₂ to stimulate the storage of fats suppressed in the presence of indomethacin, a cyclooxygenase inhibitor. These pro-adipogenic effects were caused by the up-regulation of adipogenesis as evident with higher gene expression levels of adipogenesis markers. Analysis of transcript levels revealed the enhanced gene expression of two subtypes of cell-surface membrane receptors for PGD₂, namely the prostanoid DP₁ and DP₂ (chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2)) receptors together with lipocalin-type PGD synthase during the maturation phase. Specific agonists for DP₁, CRTH2, and PPARγ were appreciably effective to rescue adipogenesis attenuated by indomethacin. The action of PGD₂ was attenuated by specific antagonists for DP₁ and PPARγ. By contrast, the effect of 11d-11m-PGD₂ was more potently interfered by a selective antagonist for CRTH2 than that for DP₁ while PPARγ antagonist GW9662 had almost no inhibitory effects. These results suggest that PGD₂ exerts its pro-adipogenic effect principally through the mediation of DP₁ and PPARγ, whereas the stimulatory effect of 11d-11m-PGD₂ on adipogenesis occurs preferentially by the interaction with CRTH2.

Keywords: 11-Deoxy-11-methylene-PGD(2); Adipogenesis; CRTH2 receptor; DP(1) receptor; Prostaglandin D(2).