Differential subcellular distribution and colocalization of microsomal and soluble epoxide hydrolases in rat cortical astrocytes.

Abstract

The purpose of this study was to determine the expression, localization and subcellular distribution of microsomal (mEH) and soluble (sEH) epoxide hydrolases in cultured rat cortical astrocytes. Cultures of astrocytes were probed for mEH and sEH by immunocytochemistry, immunoblotting and enzymatic assays. Our results showed immunofluorescence for mEH and sEH, which colocalized with the astroglial cytoskeletal marker, glial fibrillary acidic protein (GFAP). Western blotting analyses for mEH revealed a protein band of molecular mass ∼50 kDa, the intensity of which was increased about 1.5‐fold, especially in the microsomal fraction. Whereas the polyclonal sEH rabbit serum recognized a protein band of molecular mass ∼62 kDa, which increased 2.0 fold in the 105,000xg supernatant over the cell lysate. The sEH rabbit serum also recognized similar protein bands in mitochondrial and nuclear fractions. The enzymatic analyses, using mEH‐ and sEH‐selective substrates further corroborated these findings. Our results suggest that astroglial cells, by expressing both mEH and sEH, may play a role in the cerebrovascular functions affected by epoxides (Funding Support: G12RR03045‐17 (ACS) and R37ES02710 (BDH)).