Genetic polymorphism of aldehyde oxidase in Donryu rats.
One of major metabolic pathways of [(+/-)-4-(4-cyanoanilino)-5,6-dihydro-7-hydroxy-7H-cyclopenta[d]-pyrimidine] (RS-8359), a selective and reversible monoamine oxidase type A inhibitor, is the aldehyde oxidase-catalyzed 2-hydroxylation at the pyrimidine ring. Donryu rats showed a dimorphic pattern for the 2-oxidation activity with about 20- to 40-fold variations in the Vmax/Km values between a low and a high activity group. The rats were classified as extensive metabolizers (EM) and poor metabolizers (PM) of RS-8359, of which ratios were approximately 1:1. One rat among the EM rats of each sex showed extremely high activity, and they were referred to as ultrarapid metabolizers. There was no significant difference in the expression levels of mRNA of aldehyde oxidase between the EM and PM rats. Analysis of nucleotide sequences showed four substitutions, of which the substitutions at 377G>A and 2604C>T caused 110Gly-Ser and 852Ala-Val amino acid changes, respectively. Amino acid residue 110 is located very near the second Fe-S center of aldehyde oxidase. Its change from nonchiral Gly to chiral Ser may result in a conformational change of aldehyde oxidase protein with the shift of isoelectric point value from 5.0 in the EM rats to 6.2 in the PM rats. The 110Gly-Ser amino acid substitution (377G>A) may be primarily responsible for the variations of aldehyde oxidase activity observed in Donryu rats, in addition to the difference of expression levels of aldehyde oxidase protein. If a new drug candidate is primarily metabolized by aldehyde oxidase, attention should be given to using a rat strain with high aldehyde oxidase activity and small individual variation.
Itoh
Kunio
K
Department of Drug Metabolism and Pharmacokinetics, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan.
Masubuchi
Akiko
A
Sasaki
Takamitsu
T
Adachi
Mayuko
M
Watanabe
Nobuaki
N
Nagata
Kiyoshi
K
Yamazoe
Yasushi
Y
Hiratsuka
Masahiro
M
Mizugaki
Michinao
M
Tanaka
Yorihisa
Y
D042931:Aldehyde Oxidase / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D019943:Amino Acid Substitution; D000818:Animals; D015153:Blotting, Western; D003600:Cytosol / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005838:Genotype; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D007525:Isoelectric Focusing / Q000379:methods; D007700:Kinetics; D008099:Liver / Q000166:cytology / Q000201:enzymology; D008163:Luminescent Measurements / Q000379:methods; D008297:Male; D008996:Monoamine Oxidase Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D009570:Nitriles / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D020641:Polymorphism, Single Nucleotide; D011743:Pyrimidines / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
D008996:Monoamine Oxidase Inhibitors; D009570:Nitriles; D011743:Pyrimidines; D012333:RNA, Messenger; C059590:RS 8359; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D042931:Aldehyde Oxidase