CYP2C40, a Unique Arachidonic Acid 16-Hydroxylase, Is the Major CYP2C in Murine Intestinal Tract

Abstract

We recently identified five different murine CYP2C cDNAs from a murine cDNA library. When expressed in a bacterial cDNA expression system, all five recombinant proteins metabolized arachidonic acid but produced distinctly different profiles. In addition, some CYP2C mRNAs were found in extrahepatic tissues, as well as in liver. Immunoblots with an antibody raised against recombinant CYP2C38, which recognizes all five murine CYP2Cs, demonstrated that among extrahepatic tissues, colon and cecum contained the highest amount of CYP2Cs. The highest concentration of CYP2Cs occurred in cecum and colon (cecum >/= proximal colon >> distal colon), with lower levels in duodenum, jejunum, and ileum. Immunohistochemical studies revealed that CYP2Cs were localized principally in epithelial cells and autonomic ganglia in gut and colon. Polymerase chain reaction amplification of reverse-transcribed mRNA using murine CYP2C-specific primers followed by cloning and sequencing identified CYP2C40 as the major CYP2C isoform expressed in murine intestinal tract. Recombinant CYP2C40 metabolized arachidonic acid in a regio- and stereospecific manner to 16(R)-HETE (hydroxyeicosatetraenoic acid) as the major product. To our knowledge, CYP2C40 is the first enzyme known to produce primarily 16-HETE. We conclude that CYP2C40 is one of the major cytochrome P450 proteins in the mouse intestinal tract. In the light of vasoactive and anti-neutrophilic effects of 16-HETE, we hypothesize that CYP2C40 may play an important role in endogenous biological functions in intestine.

Cloning, Expression, and Characterization of Three New Mouse Cytochrome P450 Enzymes and Partial Characterization of Their Fatty Acid Oxidation Activities

“…The mouse CYP2C subfamily is substantially larger and more complex than its human counterpart. Five members (CYP2C29, CYP2C37, CYP2C38, CYP2C39, and CYP2C40) have previously been reported (Matsunaga et al, 1994;Luo et al, 1998;Tsao et al, 2000Tsao et al, , 2001. Herein, we describe the cDNA clon- Fig.…”

“…CYP2C40 produces primarily 16-HETE, but also produces 14R,15S-EET and a small amount of 8S,9R-EET. CYP2C37, CYP2C38, CYP2C39 also generate HETEs (Luo et al, 1998;Tsao et al, 2000Tsao et al, , 2001.…”

“…The mouse CYP2Cs differ in their tissue distribution and catalytic function (Luo et al, 1998;Tsao et al, 2000Tsao et al, , 2001. Thus, CYP2C29 transcripts are detected mainly in liver, brain, kidney, lung, heart, intestine, adrenals, aorta, seminal vesicles, testis, and ovary.…”

The Small Intestine as a Xenobiotic-Metabolizing Organ

“…In addition, a CYP2J protein, presumably CYP2J6, was identified to be predominantly expressed in mouse small intestine and was induced by pyrazole (Xie et al, 2000). Furthermore, CYP2C40 was identified as the major CYP2C in mouse intestinal tract (Tsao et al, 2000).…”

Characterization of the Tissue Distribution of the MouseCyp2cSubfamily by Quantitative PCR Analysis

“…Both qPCR methods show that Cyp2c55, Cyp2c65, and Cyp2c66 are highly expressed in the gastrointestinal tract with similar tissue expression profiles for each isoform. Previously Cyp2c40 was identified as the major Cyp2c isoform present in the intestine (Tsao et al, 2000); however, with more sensitive and paralog-specific qPCR methods, we identified other highly expressed Cyp2c isoforms in the intestinal tract and that Cyp2c40 is predominantly expressed in female liver.…”