Exploring biophysical properties of activated T-cells using advanced fluorescence microscopy and environmentally sensitive dyes.

Lead Research Organisation: King's College London
Department Name: Physics

Abstract

Environmentally-sensitive dyes change their emission, and sometimes absorption properties, depending on their local environment - e.g. polarity, hydrophobicity, dipole moment, etc. Thus in combination with advanced fluorescence microscopy methods, they allow the direct observation and tracking of important biophysical characteristics within the cell, such as lipid order.
Lipid order is associated with the degree of packing of membrane lipids, giving rise to so-called lipid rafts or lipid domains. Lipid rafts are small, highly dynamic structures that have been proven to have a role in compartmentalising signalling molecules and thus in regulating cell signalling. However, their direct observation in live cells historically has been challenging because of their small size and dynamic nature. One example of a process where lipid rafts are believed to play a crucial role is the formation of an immunological synapse between a T-cell and an Antigen Presenting Cell (APC) - a process which requires major structural rearrangements within the cell and the recruitment and recycling of numerous signalling molecules.
This project seeks to quantify the dynamic behaviour of intracellular lipids and proteins in T-cells during IS formation using the above mentioned dyes and live cell super-resolution imaging using techniques such as Structured Illumination Microscopy, TIRF and possibly single-molecule localisation methods. It will aim to see the relation between lipid order, vesicle dynamics and cargo transported to and recycled at the interface, as well as the role of other cellular components e.g. actin.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509498/1 30/09/2016 29/09/2021
1948490 Studentship EP/N509498/1 30/09/2017 28/02/2022 Iveta Todorova Ivanova
EP/R513064/1 30/09/2018 29/09/2023
1948490 Studentship EP/R513064/1 30/09/2017 28/02/2022 Iveta Todorova Ivanova
 
Description Preliminary results, which investigated the role of intracellular vesicle lipid order (packing) in the process of endocytosis at the T-cell vescicle immune synapse, show that tlipid order affects vesicle dynamics very differently depending on whether endocytosis at the synapse has been inhibited or not. For example, for control cells more tightly packed vesicles are associated with less linear behaviour, while the opposite is true for cells where endocytosis has been inhibited. Furthermore, endocytosis-inhibited cells show slightly higher average vesicle lipid order, consistent with more plasma membrane vesicles remaining at the synapse, as well as more "caged" behaviour, compared to control cells.
Exploitation Route Further studies have to be done to confirm and establish the meaning of these observations, but these preliminary results show vesicle lipid order at the T-cell synapse as a regulatory mechanism is an area worth exploring. If successful, these findings could potentially be used in the development of drugs which target vesicles to enter cells via endocytosis.
Sectors Healthcare,Pharmaceuticals and Medical Biotechnology