Matrix metalloproteinase 3 is present in the cell nucleus and is involved in apoptosis

Am J Pathol. 2006 Oct;169(4):1390-401. doi: 10.2353/ajpath.2006.060005.

Abstract

Matrix metalloproteinase (MMP)-3 is a protease involved in cancer progression and tissue remodeling. Using immunofluorescence and immunoelectron microscopy, we identified nuclear localization of MMP-3 in several cultured cell types and in human liver tissue sections. Western blot analysis of nuclear extracts revealed two immunoreactive forms of MMP-3 at 35 and 45 kd, with the 35-kd form exhibiting caseinolytic activity. By transient transfection, we expressed active MMP-3 fused to the enhanced green fluorescent protein (EGFP/aMMP-3) in Chinese hamster ovary cells. We showed that EGFP/aMMP-3 translocates into the nucleus. A functional nuclear localization signal was demonstrated by the loss of nuclear translocation after site-directed mutagenesis of a putative nuclear localization signal and by the ability of the MMP-3 nuclear localization signal to drive a heterologous protein into the nucleus. Finally, expression by Chinese hamster ovary cells of EGFP/aMMP-3 induced a twofold increase of apoptosis rate, compared with EGFP/pro-MMP-3, which does not translocate to the nucleus. Increased apoptosis was abolished by site-directed mutagenesis of the catalytic site of MMP-3 or by using the MMP inhibitor GM6001. This study elucidates for the first time the mechanisms of nuclear localization of a MMP and shows that nuclear MMP-3 can induce apoptosis via its catalytic activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Apoptosis*
  • CHO Cells
  • Cell Nucleus / enzymology*
  • Cricetinae
  • Humans
  • Matrix Metalloproteinase 3 / analysis*
  • Matrix Metalloproteinase 3 / chemistry
  • Matrix Metalloproteinase 3 / metabolism*
  • Molecular Sequence Data
  • Nuclear Localization Signals
  • Tumor Cells, Cultured

Substances

  • Nuclear Localization Signals
  • Matrix Metalloproteinase 3