Sp1 and Sp3 transcription factors mediate malondialdehyde-induced collagen α1(I) gene expression in cultured hepatic stellate cells

Abstract

Malondialdehyde, the end product of lipid peroxidation, has been shown to stimulate collagen α1(I) (Colla1) gene expression. However, mechanisms of this effect are unclear. The purpose of this study was to clarify these mechanisms. Rat hepatic stellate cells were cultured in the presence of 200 μM malondialdehyde, and the effects on collagen gene expression and the binding of nuclear proteins to the colla1 promoter were analyzed. Malondialdehyde treatment induced an increase in the cellular levels of colla1 mRNA that was abrogated by pretreating cells with cycloheximide, p-hydroxymercuribenzoate, pyridoxal 5′-phosphate, and mithramycin. Transient transfections showed that malondialdehyde exerted its effect through regulatory elements located between -220 and -110 bp of the colla1 promoter. Gel retardation assays demonstrated that malondialdehyde increased the binding of nuclear proteins to two elements located between -161 and -110 bp of the colla1 promoter. These bindings were supershifted with Sp1 and Sp3 antibodies. Finally, malondialdehyde increased cellular levels of the Sp1 and Sp3 proteins and Sp1 mRNA. Our data indicated that treatment of hepatic stellate cells with malondialdehyde stimulated colla1 gene expression by inducing the synthesis of Sp1 and Sp3 and their binding to two regulatory elements located between -161 and -110 bp of the colla1 promoter.