beta(3)A-integrin downregulates the urokinase-type plasminogen activator receptor (u-PAR) through a PEA3/ets transcriptional silencing element in the u-PAR promoter

Mol Cell Biol. 2001 Mar;21(6):2118-32. doi: 10.1128/MCB.21.6.2118-2132.2001.

Abstract

Migration of cells requires interactions with the extracellular matrix mediated, in part, by integrins, proteases, and their receptors. Previous studies have shown that beta(3)-integrin interacts with the urokinase-type plasminogen activator receptor (u-PAR) at the cell surface. Since integrins mediate signaling into the cell, the current study was undertaken to determine if in addition beta(3)-integrin regulates u-PAR expression. Overexpression of beta(3)-integrin in CHO cells, which are avid expressers of the receptor, downregulated u-PAR protein and mRNA expression. The u-PAR promoter (-1,469 bp) that is normally constitutively active in CHO cells was downregulated by induced beta(3)-integrin expression. A region between -398 and -197 bp of the u-PAR promoter was critical for beta(3)-integrin-induced downregulation of u-PAR promoter activity. Deletion of the PEA3/ets motif at -248 bp substantially impaired the ability of beta(3)-integrin to downregulate the u-PAR promoter, suggesting that the PEA3/ets site acts as a silencing element. An expression vector encoding the transcription factor PEA3 caused inhibition of the wild-type but not the PEA3/ets-deleted u-PAR promoter. The PEA3/ets site bound nuclear factors from CHO cells specifically, but binding was enhanced when beta(3)-integrin was overexpressed. A PEA3 antibody inhibited DNA-protein complex formation, indicating the presence of PEA3. Downregulation of the u-PAR promoter was achieved by the beta(3)A-integrin isoform but not by other beta(3)-integrin isoforms and required the cytoplasmic membrane NITY(759) motif. Moreover, overexpression of the short but not the long isoform of the beta(3)-integrin adapter protein beta(3)-endonexin blocked u-PAR promoter activity through the PEA3/ets binding site. Thus, besides the physical interaction of beta(3)-integrin and u-PAR at the cell surface, beta(3) signaling is implicated in the regulation of u-PAR gene transcription, suggesting a mutual regulation of adhesion and proteolysis receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, CD / genetics
  • Antigens, CD / metabolism*
  • Base Sequence
  • Binding Sites
  • CHO Cells
  • Cricetinae
  • Cytoplasm / metabolism
  • Down-Regulation
  • Gene Expression Regulation
  • Integrin beta3
  • Molecular Sequence Data
  • Nuclear Proteins
  • Platelet Membrane Glycoproteins / genetics
  • Platelet Membrane Glycoproteins / metabolism*
  • Promoter Regions, Genetic
  • Protein Structure, Tertiary
  • Proteins / genetics
  • Proteins / metabolism
  • Receptors, Cell Surface / genetics*
  • Receptors, Cell Surface / metabolism
  • Receptors, Urokinase Plasminogen Activator
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Regulatory Sequences, Nucleic Acid*
  • Transcription, Genetic*

Substances

  • Antigens, CD
  • ITGB3BP protein, human
  • Integrin beta3
  • Nuclear Proteins
  • Platelet Membrane Glycoproteins
  • Proteins
  • Receptors, Cell Surface
  • Receptors, Urokinase Plasminogen Activator
  • Recombinant Proteins