Localisation of MT1-MMP to motility-associated structures
Author(s)
Woskowicz, Anna
Type
Thesis
Abstract
MT1-MMP is a crucial enzyme for cellular invasion in tissues, and its
polarised cell surface localisation is thought to be an important regulatory
mechanism. In this thesis, the mechanisms regulating localisation of MT1-MMP
to motility-associated structures were investigated. Using a series of MT1-MMP
domain deletion mutants, it was found that an eight amino acid region in the
catalytic domain called the “MT-Loop” is involved in localisation of the enzyme to
matrix attachment sites. A previously described mechanism by which MT1-MMP
localises to lamellipodia is association with CD44. Interestingly, knockdown of the
CD44 in HT-1080 cells increased MT1-MMP localisation to the matrix attachment
sites, whereas CD44 overexpression in COS-7 cells decreased this localisation.
These results indicate that CD44-mediated localisation to lamellipodia may
compete with the localisation to the matrix attachment sites. One of the
previously reported mechanisms localising MT1-MMP to the matrix attachment
sites is by targeting the enzyme to cortactin-mediated invadopodia structures.
However, silencing of the cortactin gene in HT-1080 cells unexpectedly
enhanced this localisation, suggesting that invadopodia may not be required. For
MT1-MMP to appear on the cell surface, the newly expressed molecules need to
be trafficked from the trans-Golgi network to the plasma membrane by kinesin
motor proteins (KIFs). 17 KIFs were tested for their involvement in the
intracellular trafficking of MT1-MMP-containing vesicles. Silencing of the KIF3A
or KIF13A genes markedly decreased MT1-MMP-dependent gelatin and collagen
film degradation, whereas silencing of the KIF9 and KIF1C genes enhanced
degradation of the underlying matrix. These and other data presented in this
thesis suggest that KIF3A, KIF13A, KIF9 and KIF1C may be involved in vesicle
trafficking of MT1-MMP to different areas of the plasma membrane and regulate
spatial localisation of the enzyme. Taken together, these findings indicate that
polarised cell surface localisation of MT1-MMP is regulated by multiple
mechanisms, which may be important for the enzyme to promote cellular
invasion in different microenvironments.
polarised cell surface localisation is thought to be an important regulatory
mechanism. In this thesis, the mechanisms regulating localisation of MT1-MMP
to motility-associated structures were investigated. Using a series of MT1-MMP
domain deletion mutants, it was found that an eight amino acid region in the
catalytic domain called the “MT-Loop” is involved in localisation of the enzyme to
matrix attachment sites. A previously described mechanism by which MT1-MMP
localises to lamellipodia is association with CD44. Interestingly, knockdown of the
CD44 in HT-1080 cells increased MT1-MMP localisation to the matrix attachment
sites, whereas CD44 overexpression in COS-7 cells decreased this localisation.
These results indicate that CD44-mediated localisation to lamellipodia may
compete with the localisation to the matrix attachment sites. One of the
previously reported mechanisms localising MT1-MMP to the matrix attachment
sites is by targeting the enzyme to cortactin-mediated invadopodia structures.
However, silencing of the cortactin gene in HT-1080 cells unexpectedly
enhanced this localisation, suggesting that invadopodia may not be required. For
MT1-MMP to appear on the cell surface, the newly expressed molecules need to
be trafficked from the trans-Golgi network to the plasma membrane by kinesin
motor proteins (KIFs). 17 KIFs were tested for their involvement in the
intracellular trafficking of MT1-MMP-containing vesicles. Silencing of the KIF3A
or KIF13A genes markedly decreased MT1-MMP-dependent gelatin and collagen
film degradation, whereas silencing of the KIF9 and KIF1C genes enhanced
degradation of the underlying matrix. These and other data presented in this
thesis suggest that KIF3A, KIF13A, KIF9 and KIF1C may be involved in vesicle
trafficking of MT1-MMP to different areas of the plasma membrane and regulate
spatial localisation of the enzyme. Taken together, these findings indicate that
polarised cell surface localisation of MT1-MMP is regulated by multiple
mechanisms, which may be important for the enzyme to promote cellular
invasion in different microenvironments.
Date Issued
2010-09
Date Awarded
2011-05
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Itoh, Yoshifumi
Creator
Woskowicz, Anna
Publisher Department
Medicine: Kennedy Institute of Rheumatology
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)