Regulation of gamma-glutamylcysteine synthetase regulatory subunit (GLCLR)gene expression: Identification of the major transcriptional start site inHT29 cells
Dc. Galloway et al., Regulation of gamma-glutamylcysteine synthetase regulatory subunit (GLCLR)gene expression: Identification of the major transcriptional start site inHT29 cells, BBA-GENE ST, 1446(1-2), 1999, pp. 47-56
Citations number
29
Categorie Soggetti
Molecular Biology & Genetics
Journal title
BIOCHIMICA ET BIOPHYSICA ACTA-GENE STRUCTURE AND EXPRESSION
gamma-Glutamylcysteine synthetase (GCS) is of major importance in glutathio
ne homeostasis. The GCS heterodimer is composed of catalytic (heavy subunit
, GCS(h)) and regulatory (light subunit, GCS(l)) subunits. Regulation of th
e human GCS(l) subunit gene (GLCLR) expression was studied as GCS(l) has a
critical role in glutathione synthesis. The minimal basal expression of GLC
LR was found to be mediated by a region between nt -205 and -318. The major
transcriptional start site in HT29 cells was located within this region at
nt -283. A region between nt -411 and -447 was identified as having a pote
ntial involvement in the negative regulation of GLCLR expression. In order
to study the transcriptional regulation of GCS(l) by oxidant stress, HepG2
cells were treated with sodium nitroprusside (SNP). SNP (1.5 mM) was found
to increase glutathione levels by 2-fold, as well as GCS activity by 6-fold
. This is accompanied by a co-ordinate increase in the levels of the both t
he GCS(l) and GCSh subunits, each by approximately 2-fold. The transcriptio
nal activity of the GLCLR gene was increased by approximately 2.5-fold in S
NP-treated cells. (C) 1999 Elsevier Science B.V. All rights reserved.