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Estradiol suppresses mesangial cell type I collagen synthesis via activation of the MAP kinase cascade

We have previously shown that estradiol suppresses the synthesis of type I collagen by murine mesangial cells grown in the presence of serum via activation of the transcription factor activator protein-1 (AP-1). We hypothesized that estradiol upregulates AP-1 via activation of the mitogen-activated...

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Bibliographic Details
Published in:American journal of physiology. Renal physiology 1999-12, Vol.277 (6), p.F875-F881
Main Authors: Neugarten, Joel, Medve, Ildiko, Lei, Jun, Silbiger, Sharon R.
Format: Article
Language:English
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Summary:We have previously shown that estradiol suppresses the synthesis of type I collagen by murine mesangial cells grown in the presence of serum via activation of the transcription factor activator protein-1 (AP-1). We hypothesized that estradiol upregulates AP-1 via activation of the mitogen-activated protein (MAP) kinase cascade, a signal transduction pathway that regulates AP-1 activity. Estradiol (10 −10 to 10 −7 M) upregulated the MAP kinase pathway in murine mesangial cells grown in the presence of serum in a dose-dependent manner. Activation was evident by 1 min, peaked at 10 min, and was completely dissipated by 2 h. In contrast, estradiol had no significant effect on total (phosphorylated + unphosphorylated) p44 extracellular signal-related protein kinase (ERK) or p42 ERK. Nuclear extracts isolated from mesangial cells treated with estradiol showed increased binding to a consensus sequence AP-1 binding oligonucleotide in gel shift assays. In contrast, nuclear extracts from cells exposed to PD-98059, a highly selective inhibitor of MAP kinase-ERK kinase 1 (MEK1) and MEK2, showed reduced binding. In addition, PD-98059 antagonizes the enhanced binding induced by estradiol. Estradiol (10 −9 M) suppressed mesangial cell type I collagen synthesis (37.8 ± 2.4%, expressed as a percentage of control values, P < 0.001 vs. control). In contrast, PD-98059 increased type I collagen synthesis (344.6 ± 98.8, P < 0.01) and reversed the suppression of type I collagen synthesis induced by estradiol. The effects of estradiol, PD-98059, and PD-98059 plus estradiol on type I collagen protein synthesis were closely paralleled by their effects on steady-state levels of mRNA for the α 1 chain of type I collagen. These data suggest that estradiol suppresses type I collagen synthesis via upregulation of the MAP kinase cascade, leading to stimulation of AP-1 activity.
ISSN:1931-857X
1522-1466
DOI:10.1152/ajprenal.1999.277.6.F875