Am. J. Respir. Cell Mol. Biol.,
Volume 20, Number 1, January, 1999 143-152
Expression and Inducibility of Alpha, Pi, and Mu Glutathione S-Transferase
Protein and mRNA in Murine Lung
Poh-Gek
Forkert,
Darryl
D'Costa,
and
Majid
El-Mestrah
Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada
This investigation sought to establish the cellular expression and distribution of the alpha, pi, and mu
classes of glutathione S-transferase (GST) enzymes in murine lung under control conditions and after
treatment with tert-butyl-4-hydroxyanisole (BHA). Immunohistochemical and in situ hybridization studies
were used to identify lung cells that were labeled for the GST subunits Yp, Ya, and Yb1. Immunoblotting of cytosolic proteins produced single bands of 28, 29, and 31 kD for Ya, Yp, and Yb1, respectively, in samples from untreated and BHA-treated mice. Treatment with BHA increased Ya and Yp reactivity, but this
was not as marked for Yb1. Immunohistochemical staining for the Yp, Ya, and Yb1 subunits was localized
in bronchioles and parenchyma of untreated and BHA-treated mice. Bronchiolar Clara and alveolar type II
cells were stained to the greatest extent for all of the GST subunits. BHA treatment produced increased staining that was most pronounced in the bronchiolar epithelium. Ya and Yp were localized in the cytoplasm and nucleus, whereas Yb1 was found mainly in the cytoplasm. Immunoblots of extracted nuclear
proteins revealed a band of 29 kD for Ya, with increased immunoreactivity in BHA-treated mice. In situ
hybridization done with oligonucleotide probes showed abundant silver grains representing Ya, Yp, and
Yb1 messenger RNA (mRNA) transcripts in the bronchioles. Grains were also localized in alveolar septa,
and were most numerous in type II cells. Quantitative image analysis confirmed good agreement between
relative levels of protein and mRNA transcripts. Quantities of mRNA transcripts for all subunits were increased in the parenchyma by BHA treatment, but the magnitudes of induction were most striking for Ya
and Yp in the bronchioles. These results demonstrated that Ya, Yp, and Yb1 reside in specific lung areas
and cells, and that in induced states, their increased expression is accompanied by increased mRNA.
