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Cytoplasmic tail-dependent internalization of membrane-type 1 matrix metalloproteinase is important for its
1Division of Cancer Cell Research, Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan.
Abstract:
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.
Insights
Membrane-type 1 matrix metalloproteinase (MT1-MMP) internalization regulates cell migration. Specific cytoplasmic tail sequences control MT1-MMP
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Membrane-type 1 matrix metalloproteinase (MT1-MMP) degrades extracellular matrix (ECM) and is crucial for cell migration, particularly in invasive cancers.
- MT1-MMP localizes to the cell migration edge, but its regulation during migration remains unclear.
Purpose of the Study:
- To investigate the mechanism regulating MT1-MMP during cell migration.
- To identify the role of MT1-MMP internalization in cell migration and invasion.
Main Methods:
- Investigated MT1-MMP internalization using mutagenesis of its cytoplasmic tail.
- Utilized co-localization studies with clathrin-coated vesicles and adaptor protein 2 (AP2) binding assays.
- Assessed the impact of internalization-defective mutants on cell migration and invasion.
Main Results:
- MT1-MMP internalization is dependent on specific di-leucine and tyrosine residues in its cytoplasmic tail (LLY573).
- The mu2 subunit of AP2 binds to the LLY573 sequence, mediating internalization via clathrin-coated pits.
- Mutations disrupting internalization led to MT1-MMP accumulation at the cell edge but did not affect net proteolytic activity.
- Internalization-defective MT1-MMP mutants failed to enhance cell migration and invasion.
Conclusions:
- Dynamic turnover of MT1-MMP at the cell migration edge via internalization is essential for its function in cell migration and invasion.
- Cytoplasmic tail sequences critically regulate MT1-MMP localization and activity during cellular processes.