Monoclonal antibodies reveal multiple forms of expression of human microsomal epoxide hydrolase

Abstract

In a previous study, we developed five kinds of monoclonal antibodies against different portions of human mEH: three, anti-N-terminal; one, anti-C-terminal; one, anti-conformational epitope. Using them, we stained the intact and the permeabilized human cells of various kinds and performed flow cytometric analysis. Primary hepatocytes and peripheral blood mononuclear cells (PBMC) showed remarkable differences. On the surface, hepatocytes exhibited 4 out of 5 epitopes whereas PBMC did not show any of the epitopes. mEH was detected inside of both cell types, but most prominent expression was observed for the conformational epitope in the hepatocytes and the two N-terminal epitopes in PBMC. These differences were also observed between hepatocyte-derived cell lines and mononuclear cell-derived cell lines. In addition, among each group, there were several differences which may be related to the cultivation, the degree of differentiation, or the original cell subsets. We also noted that two glioblastoma cell lines reveal marked expression of the conformational epitope on the surface which seemed to correlate with the brain tumor-associated antigen reported elsewhere. Several cell lines were also underwent selective permeabilization before flow cytometric analysis, and we noticed that the topological orientation of mEH on the ER membrane in those cells was in accordance with the previous report. However, the orientation on the cell surface was inconsistent with the report and had a great variation between the cells. These findings show the multiple mode of expression of mEH which may be possibly related to the multiple roles that mEH plays in different cells.

A novel activity of microsomal epoxide hydrolase: metabolism of the endocannabinoid 2-arachidonoylglycerol

“…EPHX1 may participate in an important pathway in these physiological and pathological processes by providing free AA. Interestingly, a recent study demonstrated multiple forms of expression of EPHX1, and the results implicated the multiple roles of EPHX1 in various cells ( 41 ). In the current study, an EPHX1 form(s) responsible for 2-AG hydrolysis was not characterized, and this possibility deserves future detailed investigation.…”

Microsomal epoxide hydrolase 1 (EPHX1): Gene, structure, function, and role in human disease

“…Strong to moderate immunohistochemical EPHX1 protein staining was observed in synovial blood vessels and lining cells (Backman et al 1999). Moreover, it was shown that the topology of EPHX1 on the cell surface (Alves et al 1993) greatly varies between different cell types (Duan et al 2012). …”