Role of soluble epoxide hydrolase phosphatase activity in the metabolism of lysophosphatidic acids.

The EPXH2 gene encodes for the soluble epoxide hydrolase (sEH), which has two distinct enzyme activities: epoxide hydrolase (Cterm-EH) and phosphatase (Nterm-phos). The Cterm-EH is involved in the metabolism of epoxides from arachidonic acid and other unsaturated fatty acids, endogenous chemical mediators that play important roles in blood pressure regulation, cell growth, inflammation and pain. While recent findings suggested complementary biological roles for Nterm-phos, its mode of action is not well understood. Herein, we demonstrate that lysophosphatidic acids are excellent substrates for Nterm-phos. We also showed that sEH phosphatase activity represents a significant (20-60%) part of LPA cellular hydrolysis, especially in the cytosol. This possible role of sEH on LPA hydrolysis could explain some of the biology previously associated with the Nterm-phos. These findings also underline possible cellular mechanisms by which both activities of sEH (EH and phosphatase) may have complementary or opposite roles.