The cellular redox state is altered in a number of pathological condit
ions, including various forms of glomerular injury and diabetes. For e
xample, glucose, via the pentose phosphate pathway generates NADPH, wh
ich maintains glutathione (GSH) (part of a major intracellular reducin
g system) in its reduced state. GSH in turn influences the activity of
transcription factors on gene expression. We therefore examined wheth
er changes in cellular GSH influence total collagen synthesis and mRNA
levels for collagen I, collagen IV and TGF-beta in SV-40 transformed
mouse mesangial cells (MC) maintained in either 5 or 25 mM glucose med
ia. Total intracellular GSH was increased by N-acetylcysteine (NAC; 10
mM) or decreased with the GSH synthesis inhibitor buthionine sulfoxim
ine (BSO; 0.2 mM) in MC. NAC increased H-3-proline incorporation into
collagenase-sensitive protein while BSO decreased it under both glucos
e conditions. The presence of BSO did not reverse the increased collag
en synthesis seen in the NAC stimulated cells. Northern blot analysis
showed increased mRNA levels for collagen I, collagen IV and TGF-beta
in cells grown in high glucose (25 mw). NAC increased the mRNA for all
three compounds while BSO alone had no effect on these mRNA levels. H
owever, BSO reversed the increased mRNA levels for collagen I, IV and
TGF-beta seen in the presence of NAC. These findings suggest that the
cellular redox state may influence gene transcription in MC, and may h
ave implications in explaining injury-associated alterations of mesang
ial matrix generation.