MOLECULAR-CLONING AND EXPRESSION OF MURINE LIVER SOLUBLE EPOXIDE HYDROLASE

A clofibrate-induced mouse liver cDNA library was prepared and used to isolate the coding sequence for soluble epoxide hydrolase. A 1668-bas e pair (bp) clone was isolated and found to contain a 1269-bp open rea ding frame coding for 423 amino acids. Subsequent RNA polymerase chain reaction resulted in the isolation of 396 bp of additional 5'-sequenc e. Translation of the resulting 1659-bp open reading frame produced a 553-residue protein (62,527 Da) containing deduced peptide segments th at matched the amino acid sequences of six peptide fragments isolated previously from CNBr digests of pure murine soluble epoxide hydrolase. Neither the DNA nor the protein sequence showed significant similarit y to other currently published sequences. Structural analysis of the s oluble epoxide hydrolase coding region suggested at least one potentia l regulatory motif. Expression of the composite cDNA in COS-7 cells re sulted in a 5-10-fold increase in soluble epoxide hydrolase activity a nd a similar increase in soluble epoxide hydrolase protein amount comp ared to mock-transfected or vector control-transfected cells. Treatmen t of C57BL/6J mice with clofibrate led to an approximately 4-fold incr ease in both soluble epoxide hydrolase enzyme activity and steady-stat e mRNA levels.