Lens epithelium-derived growth factor relieves transforming growth factor-beta1-induced transcription repression of heat shock proteins in human lens epithelial cells

J Biol Chem. 2003 May 30;278(22):20037-46. doi: 10.1074/jbc.M212016200. Epub 2003 Mar 20.

Abstract

Lens epithelium-cell derived growth factor (LEDGF) is a transcriptional activator. It protects the cells by binding to cis-stress response ((A/T)GGGG(T/A)), and heat shock (HSE; nGAAn) elements in the stress genes and activating their transcription. Transforming growth factor-beta (TGF-beta) has been implicated in the control of tissue homeostasis, terminal differentiation, and apoptosis. Here we provide evidence that TGF-beta1 down-regulates LEDGF expression and diminishes its affinity for DNA during TGF-beta1-induced phenotypic changes and apoptosis in human lens epithelial cells. Surprisingly, TGF-beta1 treatment for 48 h markedly decreased the LEDGF, Hsp27, and alphaB-crystallin promoter activities with the decrease of abundance of LEDGF mRNA and protein. Deletion mutants of the LEDGF promoter showed that one TGF-beta1 inhibitory element (TIE) like sequence nnnTTGGnnn (-444 to -433) contributed to this negative regulation. Mutation of TIE (TTGG to TATT) abolished the down-regulation of the LEDGF promoter. Gel mobility and supershift assays showed that LEDGF in the nuclear extracts of TGF-beta1-treated human lens epithelial cells did not bind to stress-response elements and HSE. The TGF-beta1-induced down-regulation of LEDGF, Hsp27, and alphaB-crystallin promoters activity was reversed by cotransfection with a plasmid expressing LEDGF. Because overexpression of LEDGF was able to relieve TGF-beta1 and/or stress-induced changes, it would be a candidate molecule to postpone age-related degenerating disorders.

Publication types

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

MeSH terms

  • Base Sequence
  • Cell Lineage
  • DNA
  • Down-Regulation / physiology*
  • Epithelial Cells / metabolism
  • Heat-Shock Proteins / genetics*
  • Humans
  • Intercellular Signaling Peptides and Proteins / genetics
  • Intercellular Signaling Peptides and Proteins / physiology*
  • Lens, Crystalline / cytology
  • Lens, Crystalline / metabolism*
  • Molecular Sequence Data
  • Promoter Regions, Genetic
  • Transforming Growth Factor beta / physiology*

Substances

  • Heat-Shock Proteins
  • Intercellular Signaling Peptides and Proteins
  • Transforming Growth Factor beta
  • lens epithelium-derived growth factor
  • DNA