Characterization of phenotypes in Gstm1-null mice by cytosolic and in vivo metabolic studies using 1,2-dichloro-4-nitrobenzene.
Glutathione S-transferase Mu 1 (GSTM1) has been regarded as one of the key enzymes involved in phase II reactions in the liver, because of its high expression level. In this study, we generated mice with disrupted glutathione S-transferase Mu 1 gene (Gstm1-null mice) by gene targeting, and characterized the phenotypes by cytosolic and in vivo studies. The resulting Gstm1-null mice appeared to be normal and were fertile. Expression analyses for the Gstm1-null mice revealed a deletion of Gstm1 mRNA and a small decrease in glutathione S-transferase alpha 3 mRNA. In the enzymatic study, GST activities toward 1,2-dichloro-4-nitrobenzene (DCNB) and 1-chloro-2,4-dinitrobenzene (CDNB) in the liver and kidney cytosols were markedly lower in Gstm1-null mice than in the wild-type control. Gstm1-null mice had GST activities of only 6.1 to 21.0% of the wild-type control to DCNB and 26.0 to 78.6% of the wild-type control to CDNB. After a single oral administration of DCNB to Gstm1-null mice, the plasma concentration of DCNB showed larger AUC0-24 (5.1-5.3 times, versus the wild-type control) and higher Cmax (2.1-2.2 times, versus the wild-type control), with a correspondingly lower level of glutathione-related metabolite (AUC0-24, 9.4-17.9%; and Cmax, 9.7-15.6% of the wild-type control). In conclusion, Gstm1-null mice showed markedly low ability for glutathione conjugation to DCNB in the cytosol and in vivo and would be useful as a deficient model of GSTM1 for absorption, distribution, metabolism, and excretion/toxicology studies.
Fujimoto
Kazunori
K
Medicinal Safety Research Laboratories, Sankyo Co., Ltd., 717 Horikoshi, Fukuroi, Shizuoka 437-0065, Japan. kazunf@sankyo.co.jp
Arakawa
Shingo
S
Shibaya
Yukari
Y
Miida
Hiroaki
H
Ando
Yosuke
Y
Yasumo
Hiroaki
H
Hara
Ayako
A
Uchiyama
Minoru
M
Iwabuchi
Haruo
H
Takasaki
Wataru
W
Manabe
Sunao
S
Yamoto
Takashi
T
D000284:Administration, Oral; D000818:Animals; D001711:Biotransformation; D003600:Cytosol / Q000201:enzymology; D004137:Dinitrochlorobenzene / Q000378:metabolism; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D051549:Glutathione S-Transferase pi / Q000235:genetics / Q000378:metabolism; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D009578:Nitrobenzenes / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D012737:Sex Factors
D004137:Dinitrochlorobenzene; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase; D007527:Isoenzymes; D009578:Nitrobenzenes; D012333:RNA, Messenger; C028328:1,2-dichloro-4-nitrobenzene; C496557:Gstp1 protein, mouse