Cytoplasmic tail-dependent internalization of membrane-type 1 matrix metalloproteinase is important for its invasion-promoting activity.
Membrane-type 1 matrix metalloproteinase (MT1-MMP) is an integral membrane proteinase that degrades the pericellular extracellular matrix (ECM) and is expressed in many migratory cells, including invasive cancer cells. MT1-MMP has been shown to localize at the migration edge and to promote cell migration; however, it is not clear how the enzyme is regulated during the migration process. Here, we report that MT1-MMP is internalized from the surface and that this event depends on the sequence of its cytoplasmic tail. Di-leucine (Leu571-572 and Leu578-579) and tyrosine573 residues are important for the internalization, and the mu2 subunit of adaptor protein 2, a component of clathrin-coated pits for membrane protein internalization, was found to bind to the LLY573 sequence. MT1-MMP was internalized predominantly at the adherent edge and was found to colocalize with clathrin-coated vesicles. The mutations that disturb internalization caused accumulation of the enzyme at the adherent edge, though the net proteolytic activity was not affected much. Interestingly, whereas expression of MT1-MMP enhances cell migration and invasion, the internalization-defective mutants failed to promote either activity. These data indicate that dynamic turnover of MT1-MMP at the migration edge by internalization is important for proper enzyme function during cell migration and invasion.
Uekita
T
T
Division of Cancer Cell Research, Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan.
Itoh
Y
Y
Yana
I
I
Ohno
H
H
Seiki
M
M
D000818:Animals; D016466:CHO Cells; D002465:Cell Movement / Q000502:physiology*; D022163:Clathrin-Coated Vesicles / Q000502:physiology* / Q000648:ultrastructure; D006224:Cricetinae; D003593:Cytoplasm / Q000502:physiology; D006801:Humans; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D014162:Transfection; D014168:Transferrin / Q000378:metabolism
D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D014168:Transferrin; D019716:Tissue Inhibitor of Metalloproteinase-2; D008668:Metallothionein; D020782:Matrix Metalloproteinases; D020781:Matrix Metalloproteinase 1