Robinson, Jack ORCID: 0000-0002-0447-0822 (2022) Microcavity array supported lipid bilayers biomimetic platform for study of membrane associating proteins and membrane-protein aggregation. PhD thesis, Dublin City University.
Abstract
The plasma membrane is a semi-permeable barrier system. It separates the extracellular and
intracellular environments, supports cell-signalling, cell adhesion and membrane transport.
Proteins can be embedded in or bound peripherally to the membrane. The living cell
membrane’s profound complexity has proven a difficult environment for investigating protein
binding mechanisms. This has led to the development of biomimetic model membranes to
allow for the study of dynamics and functions of individual cell membrane processes isolated
from its complex nature. Chapter 1 describes the background to this work and overviews the
current state of the art model membranes. Chapter 2 describes the experimental studies for
MSLB preparation and analysis.
Annexins are soluble membrane-binding proteins that associate in a calcium dependent manner
with anionic phospholipids. They play roles in membrane organization, signalling and vesicle
transport and in disease states including thrombosis and inflammation. Annexin V is believed
to be involved in membrane repair. Through binding to phosphatidylserine exposed at damaged
plasma membrane the protein forms crystalline networks that stabilises small membrane tears.
Chapter 3 models this mechanism to simulate membrane healing at microcavity array
supported, asymmetric, lipid bilayers. Fluorescence spectroscopy confirmed that when DOPS
was made available at the external leaflet annexin assembled rapidly at the membrane where it
formed a layer. From electrochemical impedance, the formed layer decreased membrane
capacitance whilst reducing resistance.
Amyloid peptide aggregation, particularly Aβ (1-42), triggers neurotoxicity and is believed to play a central role in progression of Alzheimer’s disease. An exact link between Alzheimer’s disease and Aβ has not been determined but hypothesized that its self-aggregation of monomeric forms of Aβ to oligomers or fibrils has an important role in the progression of the
disease. Chapter 4 investigates the effects of DOPS on Aβ oligomer formation by varying the DOPS & Aβ concentrations, and membrane orientation. It was seen that when more DOPS is present at the external leaflet, less concentration of Aβ is needed to form oligomers before the bilayer is destroyed.
Integrins are transmembrane, conformationally switching receptors involved in cell-cell and
cell extracellular matrix adhesion. Integrins are believed to exist in conformational states that regulate their affinity to their ligands, proteins, or the extracellular matrix. Normally present in their bent resting state or can be activated to an extended state. Galectins are known to cluster with Integrin. Chapter 5 investigates Galectin-3 clustering on the different states, resting vs activated, of Integrin, α5β1. It was seen that in the resting form, galectin 3 was seen to form oligomers. However, on activation the oligomers of galectin 3 were not observed.
Metadata
Item Type: | Thesis (PhD) |
---|---|
Date of Award: | November 2022 |
Refereed: | No |
Supervisor(s): | Keyes, Tia |
Uncontrolled Keywords: | Biophysics; Fluorescence |
Subjects: | Biological Sciences > Biosensors Physical Sciences > Analytical chemistry Physical Sciences > Chemistry Physical Sciences > Electrochemistry |
DCU Faculties and Centres: | DCU Faculties and Schools > Faculty of Science and Health > School of Chemical Sciences Research Initiatives and Centres > National Centre for Sensor Research (NCSR) Research Initiatives and Centres > National Biophotonics and Imaging Platform Ireland (NBIPI) |
Funders: | Science Foundation Ireland, Irish Research Council |
ID Code: | 27309 |
Deposited On: | 17 Nov 2022 12:12 by Tia Keyes . Last Modified 17 Nov 2022 12:12 |
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