Characterization of feline cytochrome P450 2B6

Abstract

1. Little is known about drug metabolism in carnivores. Although the domestic cat (Felis catus) is an obligate carnivore and is the most common companion animal, usage and dosage of many drugs are determined according to information obtained from humans and dogs. We determined the complete cDNA sequence of CYP2B6 from the feline lung. 2. Feline CYP2B6 consists of 494 deduced amino acids, showing highest identity with the dog CYP2B ortholog, followed by those of horse, pig, primate and human. 3. Feline CYP2B6 transcripts were expressed predominantly in the lung and slightly in the small intestine but not in the liver without significant sex-dependent differences. Western blot analysis with an anti-human CYP2B6 antibody confirmed the presence of CYP2B protein in the lung but not in the liver. 4. Feline CYP2B6 proteins heterologously expressed in Escherichia coli metabolized several substrates specific to human CYP2B6, including 7-ethoxy-4-(trifluoromethyl) coumarin (EFC). The metabolic activity was strongly inhibited by medetomidine and atipamezole, potent inhibitors of canine CYP2B11 (now officially CYP2B6) as well as by ticlopidine and sertraline, inhibitors selective to human CYP2B6. 5. The results suggest that feline CYP2B6 is a functional CYP2B ortholog that plays a role in the local defense mechanism in the cat respiratory system and intestine.

Kinetics of Cyclophosphamide Metabolism in Humans, Dogs, Cats, and Mice and Relationship to Cytotoxic Activity and Pharmacokinetics

“…The importance of human CYP2B6 in CP metabolism has been studied extensively, and although several isozymes are believed to contribute to CP hydroxylation, CYP2B6 is frequently singled out as most significant (Xie et al, 2003;Rodriguez-Antona and Ingelman-Sundberg, 2006). The undetectable CYP2B ortholog in short-hair cats is unexpected, but a recent study has demonstrated that cats lack apparent liver expression of their CYP2B ortholog (Okamatsu et al, 2017). Some human liver microsomes derived from patients evidently lack CYP2B6 expression, but not to the same extent as cats (Xie et al, 2003).…”

Role of cytochrome P450 2B sequence variation and gene copy number in facilitating dietary specialization in mammalian herbivores

“…In addition, we identified CYP2B variants with polar residues at residue positions 209 and 290 in both species. To date, only hydrophobic residues have been found at residue position 209 in CYP2B sequences of other species, and dog CYP2B11 Asp290 is the only known hydrophilic residue found at residue position 290 (Malenke et al., ; Nelson, ; Okamatsu et al., ). Three specialist CYP2B SRS variants (CYP2B SRS variants 14, 15, 47; Table ) contained a serine (Ser) at residue position 209, whereas seven generalist CYP2B SRS variants (CYP2B SRS variants 21, 22, 29, 43‐46, Table ) contained a threonine (Thr) at the same position.…”

Xenobiotica-metabolizing enzymes in the lung of experimental animals, man and in human lung models

“…Pre-exposure of the rats to diesel exhaust (7400 µg particles/m 3 for 4 weeks) led to a 2-fold increase of 1-nitropyrene metabolism and to a 4-fold increase of its covalent binding to lung constituents (Bond et al 1985). Wheeler et al (1990) characterized in human and baboon lung a CYP homologous to the toxicologically Oesch et al (1980), Bond et al (1988) 2.88 ± 0.27 o Bilimoria et al (1977) 0.77 a 11 a Shimada et al (1992) 1.89 ± 1.1 a 1.32 ± 0.43 a,t 4.2 ± 1.8 a 12.3 ± 2.8 a Wheeler et al (1990) EROD (1) 0.49 a 11 a ; 2.32 ± 0.26 a Shimada et al (1992), Canistro et al (2012) 2.05 ± 2.0 a 1.27 ± 0.37 a,t 8.27 ± 1.9 a 2.40 ± 0.07 a 9.20 ± 3.9 a Wheeler et al (1990), Canistro et al (2009) 1.58 ± 0.62 j 0.2 ± 0.04 m Somers et al (2007), Okamatsu et al (2017) bd 0.26 ± 0.04 a,i Castell et al 2005;Umachandran and Ioannides (2006) CECOD (1) Canistro et al (2009Canistro et al ( , 2012 BROD (1A1,2B,3A)~ 42/~ 1 d 86.9 ± 33.7 a Kastelova et al (2003), Carlson et al (1998) MROD 1A24-11 f 80 ± 0.02 a,r Bernauer et al (2006), Canistro et al (2012); 0.99 ± 0.05 a 0.3 ± 0.11 m <...>…”

“…3.7 ± 1.6b,x Shimada et al (1996a), Uehara et al (2018 8.6 ± 1.6 a Pacifici et al (1988b) 4.69 ± 1.7 a 5.73 ± 2.6 a,t 160 ± 18 a 295 ± 65 a Wheeler et al (1990) Coumarin-OH p (2A,1A,3A) bd j , < 0.32 a 0.38 ± 0.02 a,u Somers et al (2007), Uehara et al 2018< 0.32 a,v ˃7 m Uehara et al 2018, Okamatsu et al (2017) < 0.05 a Shimada et al (1996a) 30.2 ± 26.3 a Castell et al (2005) PROD (CYP2B) 0.85 a 2.5 a ; 17.3 ± 2.2 a Shimada et al1992), Canistro et al (2012) 30.3 ± 2.6 a 27.1 ± 2.53 a ;…”

“…Cytochromes P450 (CYP) Okamatsu et al (2017) observed in cat lung CYP2B6 transcripts, protein and activity. Of eight organs investigated transcripts were by far most abundant in lung, modest in small intestine, low in colon and rectum, very low in brain and heart and practically nil in liver and kidney.…”