Abstract
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.
Footnotes
-
Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
-
doi:10.1124/dmd.106.010009.
-
ABBREVIATIONS: GST, glutathione S-transferase; GSTM1, glutathione S-transferase Mu 1; GSTa or GSTa, glutathione S-transferase Alpha; Gstp, glutathione S-transferase Pi; Gstz, glutathione S-transferase Zeta; GSH, glutathione; KO, knockout; ES cell, embryonic stem cell; kb, kilobase(s); DT, diphtheria toxin A chain gene; RT-PCR, reverse transcription-polymerase chain reaction; DCNB, 1,2-dichloro-4-nitrobenzene; CDNB, 1-chloro-2,4-dinitrobenzene; GST-D activity, GST activity toward DCNB; GST-C activity, GST activity toward CDNB; HPLC, high-performance liquid chromatography; LC-MS, liquid chromatography-tandem mass spectrometry; LC-MS/MS, liquid chromatography-tandem mass spectrometry; ESI, electrospray ionization; ASK1, apoptosis signal-regulating kinase 1; bp, base pair(s).
- Received March 5, 2006.
- Accepted June 5, 2006.
- The American Society for Pharmacology and Experimental Therapeutics
DMD articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|