Abcb1 in Pigs: Molecular cloning, tissues distribution, functional analysis, and its effect on pharmacokinetics of enrofloxacin

Abstract

P-glycoprotein (P-gp) is one of the best-known ATP-dependent efflux transporters, contributing to differences in pharmacokinetics and drug-drug interactions. Until now, studies on pig P-gp have been scarce. In our studies, the full-length porcine P-gp cDNA was cloned and expressed in a Madin-Darby Canine Kidney (MDCK) cell line. P-gp expression was then determined in tissues and its role in the pharmacokinetics of oral enrofloxacin in pigs was studied. The coding region of pig Abcb1 gene was 3,861 bp, encoding 1,286 amino acid residues (Mw = 141,966). Phylogenetic analysis indicated a close evolutionary relationship between porcine P-gp and those of cow and sheep. Pig P-gp was successfully stably overexpressed in MDCK cells and had efflux activity for rhodamine 123, a substrate of P-gp. Tissue distribution analysis indicated that P-gp was highly expressed in brain capillaries, small intestine, and liver. In MDCK-pAbcb1 cells, enrofloxacin was transported by P-gp with net efflux ratio of 2.48 and the efflux function was blocked by P-gp inhibitor verapamil. High expression of P-gp in the small intestine could modify the pharmacokinetics of orally administrated enrofloxacin by increasing the Cmax, AUC and Ka, which was demonstrated using verapamil, an inhibitor of P-gp.

Molecular cloning and tissue distribution of a novel marmoset ABC transporter

“…Differences in the tissue expression pattern of ABCB1 may influence the pharmacokinetics of typical ABC transporter drugs, such as colchicine, doxorubicin, vinblastine and paclitaxel between humans and experimental animals (Scotto, ). Abundant expression of marmoset ABCB1 in small intestines and livers is consistent with the previous data of humans, dogs and pigs (Guo et al, ; Haller et al, ; Langmann et al, ; Nishimura & Naito, ), but renal ABCB1 expression was at a low level in pigs (Guo et al, ). Brain ABCB1 protein expression level was similar in humans and marmosets, but was higher (>2‐fold) in rats compared with humans (Hoshi et al, ).…”

“…Pharmacokinetic studies have reportedly indicated that aliskiren showed low bioavailability (16%) in marmosets (Waldmeier et al, 2007), similar to cynomolgus monkeys (1.4%) (Xu et al, 2010) and humans (2.6%) (Azizi, Webb, Nussberger, & Hollenberg, 2006), and was predominantly eliminated by biliary/fecal excretion, and was largely recovered in the feces of marmosets with intravenous dosing as unchanged aliskiren (up to 78%) (Waldmeier et al, 2007), but the contribution of efflux transporters for these properties has not been elucidated. Because of the importance in pharmacokinetics, ABCB1 orthologs have been identified in various species including humans, pigs, dogs, rats, hamsters, and mice (Chen et al, 1990;Devault & Gros, 1990;Endicott, Sarangi, & Ling, 1991;Guo et al, 2016;Silverman, Raunio, Gant, & Thorgeirsson, 1991;Steingold et al, 1998;Ueda et al, 1987). The expression level of ABCB1 proteins in livers is commonly much lower (1-3% of total transporter protein expression) across humans, dogs, cynomolgus monkeys and rats (Wang et al, 2015).…”

Cloning and Transcriptional Activity Analysis of the Porcine Abcb1 Gene Promoter: Transcription Factor Sp1 Regulates the Expression of Porcine Abcb1

“…The expression level and activity of P-gp differentiate greatly between individuals due to genetic variations and environmental cues ( Moriguchi et al, 2007 ). Despite an increasing interest in understanding the biological and pharmacological roles of P-gp in veterinary medicine ( Zahner et al, 2010 ; Dunn et al, 2011 ; Yokota et al, 2011 ; Guo M. et al, 2016 ; Guo T. et al, 2016 ; Wilkens et al, 2016 ), little is known about how pig P-gp is regulated. Given the high expression of P-gp at numerous physiological barriers, it is of great importance to elucidate the molecular mechanisms of P-gp expression.…”

Identification of Functional Transcriptional Binding Sites within Chicken Abcg2 Gene Promoter and Screening Its Regulators

“…It is currently recognized that the impact of drug transporters on clinically relevant drug disposition and drug-drug interactions (DDIs) is as significant as that of drug-metabolizing enzymes [1,2]. Breast cancer resistance protein (BCRP/ABCG2, encoded by the Abcg2 gene) is a known member of the ATP-binding cassette (ABC) transporter family that utilizes the hydrolysis of ATP to energize the efflux of a broad range of substrates, including commonly used antimicrobial agents licensed in veterinary medicine [3,4]. The FDA accepted BCRP as a key drug transporter involved in clinically relevant DDIs, adverse drug reactions, and therapeutic failure of drugs due to its localization in organs that are important in drug disposition [5,6].…”