Characterization of the Cytochrome P450 CYP234: Expression in Rat Small Intestine and Role in Retinoic Acid Biotransformation from Retinal

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Gregory M. Raner, Associate Professor and Graduate Director (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/

Abstract: The sites of expression in the small intestine and the function of CYP2J4, a recently identified rat cytochrome (P450) isoform found to be predominantly expressed in the small intestine, were characterized. Immunoblot analysis with a polyclonal antibody to heterologously expressed CYP2J4 revealed that expression of CYP2J4 was at the highest level in the distal duodenum and jejunum and decreased toward the ileum. Villous cells expressed higher levels of CYP2J4 than crypt cells. Isoform-specific RNA polymerase chain reaction indicated that a related P450 isoform, CYP2J3, was only a minor form in rat small intestine. Since the intestinal mucosa is exposed to high levels of dietary nutrients, we hypothesized that CYP2J4 may be active toward diet-derived factors. We determined that purified, heterologously expressed CYP2J4 is active toward all-trans- and 9-cis-retinal in reconstituted systems, producing the corresponding retinoic acids as the major products. Apparent Km values for the formation of retinoic acids were 54 and 49 µM, respectively, and apparent Vmax values were 20 and 21 nmol/min/nmol P450, respectively. These activities were readily inhibited by a polyclonal anti-CYP2J4 antibody. Rat enterocyte microsomes were also active with all-trans-retinal to produce all-trans-retinoic acid in the presence of NADPH, and the majority of retinoic acid synthesis activity was inhibited by the polyclonal anti-CYP2J4 antibody. These findings suggest that CYP2J4 plays a major role in intestinal microsomal metabolism of retinal to retinoic acid and may be involved in the maintenance of retinoid homeostasis in the small intestine in vivo.

Additional Information

Publication
Archives of Biochemistry and Biophysics 353:257-264 (1998).
Language: English
Date: 1998
Keywords
CYP2J4, Retinoic acid, Retinal, Small intestine