MAPEG expression in mouse embryonic stem cell-derived hepatic tissue system.

The expressions of membrane-associated proteins in eicosanoid and glutathione metabolism (MAPEG), a superfamily involved in both inflammation and cell protection, were investigated in an in vitro system of mouse embryonic stem (ES) cell-derived hepatic tissue. Gene expressions of all MAPEG members were demonstrated in a developmental-dependent manner in the derived hepatic tissue. The protein expression of microsomal glutathione S-transferase 1 (MGST1) was not detected until differentiating day 14. It gradually increased by maturation of hepatic tissue. The microsomes of ES cell-derived hepatic tissue possessed the MGST1-like catalytic activity. However, MGST1 from the microsome preparation could not form dimers as usual when exposed to reactive nitrogen species ONOO. Among the other members in MAPEG, weak expressions of leukotriene C(4) synthase (LTC(4)S) and microsomal prostaglandin E synthase 1 (mPGES-1) were observed. A stable expression of 5-Lipoxygenase activating protein (FLAP) appeared during the entire course of differentiation. MGST2 and MGST3 failed to express in the derived hepatic tissue, although mRNA of them do existed. In conclusion, ES cell-derived hepatic tissue possess MAPEG gene expression features, but not all protein expression could be detected, which helps to understand not only the nature of the tissue derived, but also the fate of bioartificial liver system, and may as well provide a valuable in vitro model for research in both inflammation process and toxic events in hepatological fields.