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Localization of membrane-type 1 matrix metalloproteinase in caveolae membrane domains
B Annabi1, M Lachambre, N Bousquet-Gagnon
1Laboratoire de Médecine Moléculaire, Hôpital Sainte-Justine et Université du Québec à Montréal, C.P. 8888, Succ. Centre-ville, Montréal, Québec, Canada H3C 3P8.
Abstract:
Membrane-type 1 matrix metalloproteinase (MT1-MMP) is a membrane-associated MMP that has been recently reported to have a central role in tumour cell invasion. Here we report that both the native and overexpressed recombinant forms of MT1-MMP are highly enriched in low-density Triton X-100-insoluble membrane domains that contain the caveolar marker protein caveolin 1. Moreover, the MT1-MMP-dependent activation of proMMP-2 induced by concanavalin A and cytochalasin D was correlated with the processing of MT1-MMP to its proteolytically inactive 43 kDa fragment in U-87 glioblastoma and HT-1080 fibrosarcoma tumour cell lines; this processing was also preferentially observed within the caveolar fraction. Interestingly, whereas the expression of caveolin 1 had no effect on the MT1-MMP-dependent activation of proMMP-2, its co-expression with MT1-MMP antagonized the MT1-MMP-increased migratory potential of COS-7 cells. Taken together, our results provide evidence that MT1-MMP is preferentially compartmentalized and proteolytically processed in caveolae of cancer cells. The inhibition of MT1-MMP-dependent cell migration by caveolin 1 also suggests that the localization of MT1-MMP to caveolin-enriched domains might have an important function in the control of its enzymic activity.
Insights
Membrane-type 1 matrix metalloproteinase (MT1-MMP) localizes to caveolae in cancer cells, where it is processed and its activity is regulated. This localization impacts tumor cell migration, suggesting a role for caveolae in controlling MT1-MMP function.
Area of Science:
- Cell Biology
- Molecular Oncology
- Biochemistry
Background:
- Membrane-type 1 matrix metalloproteinase (MT1-MMP) is crucial for tumor cell invasion.
- MT1-MMP is a membrane-associated enzyme involved in extracellular matrix remodeling.
Purpose of the Study:
- To investigate the subcellular localization and functional role of MT1-MMP in cancer cells.
- To determine the relationship between MT1-MMP, caveolin 1, and proMMP-2 activation.
- To explore the impact of MT1-MMP localization on cancer cell migration.
Main Methods:
- Biochemical fractionation to isolate Triton X-100-insoluble membrane domains.
- Analysis of MT1-MMP processing and proMMP-2 activation in glioblastoma and fibrosarcoma cell lines.
- Co-expression studies of MT1-MMP and caveolin 1 in COS-7 cells to assess migratory potential.
Main Results:
- MT1-MMP is highly enriched in caveolin 1-containing membrane domains.
- MT1-MMP processing to an inactive fragment occurs preferentially within caveolae.
- Caveolin 1 expression antagonizes MT1-MMP-induced cell migration, despite not affecting proMMP-2 activation.
Conclusions:
- MT1-MMP is compartmentalized and proteolytically processed within caveolae in cancer cells.
- Caveolin 1-mediated inhibition of MT1-MMP-driven migration suggests caveolae regulate MT1-MMP enzymatic activity and function.