Master of Science
Membrane-type 1 matrix metalloproteinase (MT1-MMP) is an integral multidomain membrane protease involved in extracellular matrix remodelling. No longer recognized solely as a destructive enzyme, MT1-MMP proteolytic and non-proteolytic activities are involved in a variety of cellular processes. I hypothesized that the diverse functions of MT1-MMP are dependent on domain-specific binding partner interactions that elicit a cellular response. Using a combination of co-immunoprecipitation and mass spectrometry, 248 unique proteins were isolated in MT1-MMP variant expressing MCF-7 cells. Newly identified binding partners suggest potential roles of MT1-MMP in the nucleus, endoplasmic reticulum, cytoplasm, and plasma membrane. Additionally, the cytoplasmic domain of MT1-MMP attenuates canonical transforming growth factor beta (TGF-β) signalling through an unknown mechanism. The results of this proteomic study add proteins to a growing catalogue of binding partners involved in proper localization and function of MT1-MMP.
Summary for Lay Audience
The extracellular matrix (ECM) is an interconnected network of proteins that provides structural support to cells, tissues, and organ systems. For cells, the building blocks of life, to migrate to new places within a growing organism, the ECM needs to be remodelled. It is important to note that migration is necessary for proper development and function, but abnormal cell migration is involved in various pathologies. Matrix metalloproteinases (MMPs) are proteins secreted by the cell into the ECM, where they function to break down the ECM so the cell can move freely. There are many types of MMPs that can collectively degrade all the different parts of the ECM. In my project, I studied membrane-type 1 matrix metalloproteinase (MT1-MMP). Early research deemed MT1-MMP a destructive enzyme observed in cancerous tissue. However, MT1-MMP not only degrades the ECM so the cell can move, but part of this protein extends into the cell (cytoplasmic domain), where it is observed to communicate to the cell when and where to migrate. For this reason, MT1-MMP is described as a multifunctional protease. The purpose of my research was to further investigate the function of MT1-MMP, more specifically through its interaction with other proteins. Here, 248 proteins were identified that associate with MT1-MMP in breast cancer cells. These newly identified proteins point to possible novel interactions and functions of MT1-MMP throughout the cell, not just its role as an enzyme. Additionally, removal of the cytoplasmic domain induces transforming growth factor beta (TGF-β) signalling, an important regulator of cellular processes. TGF-β signalling, in addition to having critical embryonic roles, has dual functions in tumours, acting either as a suppressor or activator. Understanding what MT1-MMP interacts with is critical due to its involvement in many important processes in development, wound healing, and disease.
Bork, Bradley, "Mass spectrometry identification of membrane-type 1 matrix metalloproteinase (MT1-MMP) binding partners following co-immunoprecipitation in MCF-7 cells" (2020). Electronic Thesis and Dissertation Repository. 7144.
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