Matrix metalloproteinase 3 is present in the cell nucleus and is involved in apoptosis.
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.
Si-Tayeb
Karim
K
INSERM E362, Université Victor Segalen Bordeaux 2, 33076 Bordeaux, France.
Monvoisin
Arnaud
A
Mazzocco
Claire
C
Lepreux
Sébastien
S
Decossas
Marion
M
Cubel
Gaëlle
G
Taras
Danièle
D
Blanc
Jean-Frédéric
JF
Robinson
Derrick R
DR
Rosenbaum
Jean
J
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D016466:CHO Cells; D002467:Cell Nucleus / Q000201:enzymology*; D006224:Cricetinae; D006801:Humans; D019278:Matrix Metalloproteinase 3 / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D014407:Tumor Cells, Cultured
D019913:Nuclear Localization Signals; D019278:Matrix Metalloproteinase 3