Widespread basal cytochrome P450 expression in extrahepatic bovine tissues and isolated cells

Abstract

Periparturient cattle face increased risk of both metabolic and infectious diseases. Factors contributing to this predisposition include oxidized polyunsaturated fatty acids, also known as oxylipids, whose production is altered during the periparturient period and in diseased cattle. Alterations in the production of oxylipids derived from cytochrome P450 (CYP450) enzymes are over-represented during times of increased disease risk and clinical disease, such as mastitis. Many of these same CYP450 enzymes additionally regulate metabolism of fat-soluble vitamins, such as A, D, and E. These vitamins are essential to maintaining immune health, yet circulating concentrations are diminished near calving. Despite this, a relatively small amount of research has focused on the roles of CYP450 enzymes outside of the liver. The aim of this paper is to describe the relative gene expression of 11 CYP450 in bovine tissues and common in vitro bovine cell models. Eight tissue samples were collected from 3 healthy dairy cows after euthanasia. In vitro samples included primary bovine aortic and mammary endothelial cells and immortalized bovine kidney and mammary epithelial cells. Quantitative real-time-PCR was carried out to assess basal transcript expression of CYP450 enzymes. Surprisingly, CYP450 mRNA was widely expressed in all tissue samples, with predominance in the liver. In vitro CYP450 expression was less robust, with several cell types lacking expression of specific CYP450 enzymes altogether. Overall, cell culture models did not reflect expression of tissue CYP450. However, when CYP450 were organized by activity, certain cell types consistently expressed specific functional groups. These data reveal the widespread expression of CYP450 in individual organs of healthy dairy cows. Widespread expression helps to explain previous evidence of significant changes in CYP450-mediated oxylipid production and fat-soluble vitamin metabolism in organ microenvi-ronments during periods of oxidative stress or disease. As such, these data provide a foundation for targeted functional experiments aimed at understanding the activities of specific CYP450 and associated therapeutic potential during times of increased disease risk.

Vitamin E analogs limit in vitro oxidant damage to bovine mammary endothelial cells

“…An additional unique and advantageous characteristic of BMEC to model the effects of vitamin E analogs is a lack of measurable CYP4F2 transcript expression (Kuhn et al, 2020). The cytochrome P450 family 4 subfamily F member 2 enzyme (CYP4F2), is thought to be the sole enzyme responsible for the breakdown of vitamin E analogs and has a preference for metabolizing non-α-tocopherol analogs of vitamin E Parker, 2002, 2007).…”

Inhibition of 20‐hydroxyeicosatetraenoic acid biosynthesis by vitamin E analogs in human and bovine cytochrome P450 microsomes

“…For this reason, experiments were additionally carried out in bovine microsomes from kidney and mammary tissues. Bovine renal tissue has the greatest CYP4F2 expression on an mRNA basis of any organ making it potentially an important contributor to systemic 20‐HETE production (Kuhn et al, 2020). Unlike the human CYP4F2 microsome preparations, whole organ bovine microsomes include most CYP450 present within a given tissue type, implying CYP4A11—a potentially considerable contributor to 20‐HETE production—is likely present and could dilute the inhibitory effects of vitamin E analogs on overall 20‐HETE concentrations (Powell et al, 1998).…”

The Physiological Roles of Vitamin E and Hypovitaminosis E in the Transition Period of High-Yielding Dairy Cows

“…In calves, the CYP4F2 mRNA level was the highest in the liver, followed by the testis, adrenal gland, duodenum, and jejunum, which have high α-Toc accumulation [35]. The CYP4F2 mRNA in lactating Holstein cows was significantly higher in the kidney than in the liver, lung, mammary gland, heart, skeletal muscle, spleen and uterus [38]. Furthermore, the hepatic [2,55] and mammary [2] CYP4F2 mRNA expression in transition dairy cows was investigated (described in Section 4).…”

“…In the last 10 years, several studies have shown evidence that the ovine [33,34] and bovine [35] liver may play an important role in the regulation of VE disposition because of the high expression of VE-related molecules. In addition, other peripheral tissues showed unique expression patterns for VE-related molecules and VE accumulation properties in cattle [2,[35][36][37][38]. These findings indicate that the expression of VE-related genes in the liver and non-hepatic tissues may be involved in the regulation of VE status in cows.…”