Matrix Metalloproteinase 3 Is Present in the Cell Nucleus and Is Involved in Apoptosis

• DOI: 10.2353/ajpath.2006.060005
• Publication Date: 2006-12-13T19:54:42Z
• Authors: Karim Si-Tayeb; Arnaud Monvoisin; Claire Mazzocco; Sébastien Lepreux; Marion Decossas; Gaëlle Cubel; Danièle Taras; Jean-Frédéric Blanc; Derrick R. Robinson; Jean Rosenbaum
• Keywords: MESH: Cell Nucleus; 0301 basic medicine; [SDV]Life Sciences [q-bio]; Molecular Sequence Data; Nuclear Localization Signals; MESH: Cricetinae; MESH: Nuclear Localization Signals; Apoptosis; [SDV.BC]Life Sciences [q-bio]/Cellular Biology; MESH: Amino Acid Sequence; CHO Cells; 03 medical and health sciences; MESH: CHO Cells; Cricetinae; Tumor Cells, Cultured; Animals; Humans; MESH: Animals; MESH: Tumor Cells, Cultured; Amino Acid Sequence; Cell Nucleus; MESH: Humans; MESH: Molecular Sequence Data; MESH: Apoptosis; [SDV] Life Sciences [q-bio]; [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology; MESH: Matrix Metalloproteinase 3; Matrix Metalloproteinase 3

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.