Anti-AP-1 activity of all-trans retinoic acid in glomerular mesangial cells

Am J Physiol. 1994 Nov;267(5 Pt 2):F805-15. doi: 10.1152/ajprenal.1994.267.5.F805.

Abstract

Functional antagonism between retinoic acid (RA) receptors and activator protein-1 (AP-1) transcription factors might regulate expression of genes involved in the response to injury in the kidney. We designed experiments to analyze the mechanisms by which RA inhibits AP-1-directed transcriptional responses in glomerular mesangial cells. RA inhibited serum-stimulated mesangial cell proliferation as assessed by measurements of [3H]thymidine uptake and cell number. In transient transfection assays with a chloramphenicol acetyltransferase reporter, RA completely blocked transcription directed by an AP-1 cis-element in cells stimulated by serum. AP-1 DNA binding was analyzed in electrophoretic gel mobility shift assays using nuclear extracts from control or RA-pretreated cells stimulated with serum. RA did not abolish AP-1 DNA binding activity under the conditions of this assay. The apparent equilibrium dissociation constant, maximal density of binding, and association rate for the AP-1-DNA interaction were similar in serum-stimulated cells or RA-pretreated cells stimulated with serum. RA repressed serum-stimulated induction of the immediate early genes c-fos and c-jun, whose protein products dimerize to form AP-1. Repression was relatively selective for c-fos/c-jun; induction of other immediate early transcription factors (junB, c-myc, and egr-1) was not downregulated by RA. That repression of c-fos by RA might contribute to anti-AP-1 activity was suggested by experiments with an antisense c-fos expression vector, which demonstrated that c-fos induction was required for serum-stimulated AP-1 activity. Together, these data demonstrate that RA antagonizes AP-1-directed transcription without inhibiting AP-1 DNA-binding in mesangial cells. Selective repression of c-fos and c-jun might contribute to the anti-AP-1 activity of RA.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blotting, Northern
  • Cattle
  • Cell Division / drug effects
  • Cells, Cultured
  • Chloramphenicol O-Acetyltransferase / biosynthesis
  • Culture Media
  • DNA / biosynthesis*
  • Dose-Response Relationship, Drug
  • Endothelins / pharmacology
  • Gene Expression / drug effects*
  • Gene Expression Regulation / drug effects
  • Genes, Immediate-Early / drug effects
  • Genes, Immediate-Early / physiology*
  • Glomerular Mesangium / cytology
  • Glomerular Mesangium / drug effects
  • Glomerular Mesangium / metabolism*
  • Kinetics
  • Male
  • Rats
  • Rats, Sprague-Dawley
  • Thymidine / metabolism
  • Transcription Factor AP-1 / antagonists & inhibitors*
  • Transcription, Genetic / drug effects
  • Transfection
  • Tretinoin / pharmacology*
  • Tritium

Substances

  • Culture Media
  • Endothelins
  • Transcription Factor AP-1
  • Tritium
  • Tretinoin
  • DNA
  • Chloramphenicol O-Acetyltransferase
  • Thymidine