Studies demonstrated ADAMTS13 possesses unique properties with a mystifying regulatory mechanism. ADAMTS13’s role is in its proteolytic function to its VWF. The disparity in the hemostatic balance between ADAMTS13 activity and the distribution of VWF multimers could result in the bleeding disorder Von Willebrand Disease (VWD) or the thrombotic disorder thrombotic thrombocytopenic purpura (TTP). ADAMTS13 is constitutively secreted as an active protease, yet VWF retains its capacity to recruit platelets. This ability makes ADAMTS13 an enigmatic protease with an unknown regulatory mechanism. Currently, the postulated regulatory mechanism of ADAMTS13 is in its open/closed conformation, yet ADAMTS13 activity is retained in both forms. Literature showed that few proteases are capable of degrading ADAMTS13 in-vitro. We hypothesize that the partial degradation of ADAMTS13 regulates its activity, thereby stabilizing VWF and promoting thrombosis. The goals of this project were to develop and optimize in-vitro plasma BioID to identify novel interactions to ADAMTS13, validate novel interactions, identify proteases capable of degrading ADAMTS13 and their proteolytic sites, and develop protease-resistant ADAMTS13 mutants as novel therapeutics to thrombotic disorders. We optimized the BioID technique to be used in-vitro in plasma, to study novel interactions with ADAMTS13. Our results identified novel potential interactions with vitronectin or plasminogen. Validation studies disregarded vitronectin’s interaction and confirmed plasminogen’s interaction through the CUB and Kringle domains in a lysine-dependent manner.
Further, the list of proteases capable of degrading ADAMTS13 was expanded to include FXIa and neutrophil-derived proteases including Cathepsin G, elastase, and hPR3. Activated neutrophils played a stronger role than coagulation proteases in degrading ADAMTS13 in vivo, while also demonstrating that elastase is a more potent regulator. Proteolytically degraded sites on ADAMTS13 were identified and proteolytic-resistant ADAMTS13 mutants were produced accordingly, which we aim to be utilized as a novel therapeutic to thrombotic disorders. / Thesis / Doctor of Philosophy (Medical Science)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/27566 |
| Date | January 2022 |
| Creators | Madarati, Hasam |
| Contributors | Kretz, Colin, Medical Sciences (Blood and Cardiovascular) |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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