title: Supported Lipid Bilayer Platform To Test Inhibitors of the Membrane Attack Complex: Insights into Biomacromolecular Assembly and Regulation.
abstract: Complement activation plays an important role in innate immune defense by triggering formation of the membrane attack complex (MAC), which is a biomacromolecular assembly that exhibits membrane-lytic activity against foreign invaders including various pathogens and biomaterials. Understanding the details of MAC structure and function has been the subject of extensive work involving bulk liposome and erythrocyte assays. However, it is difficult to characterize the mechanism of action of MAC inhibitor drug candidates using the conventional assays. To address this issue, we employ a biomimetic supported lipid bilayer platform to investigate how two MAC inhibitors, vitronectin and clusterin, interfere with MAC assembly in a sequential addition format, as monitored by the quartz crystal microbalance-dissipation (QCM-D) technique. Two experimental strategies based on modular assembly were selected, precincubation of inhibitor and C5b-7 complex before addition to the lipid bilayer or initial addition of inhibitor followed by the C5b-7 complex. The findings indicate that vitronectin inhibits membrane association of C5b-7 via a direct interaction with C5b-7 and via competitive membrane association onto the supported lipid bilayer. On the other hand, clusterin directly interacts with C5b-7 such that C5b-7 is still able to bind to the lipid bilayer, and clusterin affects the subsequent binding of other complement proteins involved in the MAC assembly. Taken together, the findings in this study outline a biomimetic approach based on supported lipid bilayers to explore the interactions between complement proteins and inhibitors, thereby offering insight into MAC assembly and regulation.
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore.|Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive, Singapore 637553, Singapore.|Institute of Molecular and Cell Biology, Agency for Science Technology and Research , Singapore 138673, Singapore.
authors.forename: Saziye
authors.initials: S
authors.lastname: Yorulmaz
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore.|Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive, Singapore 637553, Singapore.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Jackman
authors.affiliation: Institute of Molecular and Cell Biology, Agency for Science Technology and Research , Singapore 138673, Singapore.|Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore , Singapore 117599, Singapore.|Singapore Eye Research Institute, Singapore 168751, Singapore.
authors.forename: Walter
authors.initials: W
authors.lastname: Hunziker
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue, Singapore 639798, Singapore.|Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive, Singapore 637553, Singapore.|School of Chemical and Biomedical Engineering, Nanyang Technological University , 62 Nanyang Drive, Singapore 637459, Singapore.
authors.forename: Nam-Joon
authors.initials: NJ
authors.lastname: Cho
mesh_terms: D032701:Biomimetics; D051152:Clusterin / Q000737:chemistry*; D003167:Complement Activation; D003182:Complement C5 / Q000037:antagonists & inhibitors / Q000378:metabolism; D015938:Complement Membrane Attack Complex / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000378:metabolism; D019096:Vitronectin / Q000737:chemistry*
chemical_list: D051152:Clusterin; D003182:Complement C5; D015938:Complement Membrane Attack Complex; D008051:Lipid Bilayers; D008081:Liposomes; D019096:Vitronectin; C037453:complement C5b-7 complex