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The composition-function relationship of the plasma membrane

Primary Supervisor: Professor Dylan Owen

Secondary supervisor: Professor Robin May

PhD project title: The composition-function relationship of the plasma membrane

University of Registration: University of Birmingham

Project outline:

The plasma membrane regulates communication between the cell and its environment and is composed of a vast number of diverse membrane proteins and lipids. These constituents impart the membrane with physical characteristics such as thickness, rigidity, curvature and so on, which influence that communication process. The constituent molecules are acquired via two routes – they are consumed from the cell’s environment or they are built metabolically by the cell and trafficked to the plasma membrane. Thus, there exists a complex and unexplored relationship between internal metabolism and external environment which are linked by the resulting composition-function relationship of the plasma membrane, evolution and natural selection.

Nowhere is this more important than in the immune response. This project will focus on T cells: white blood cells of the immune system whose role is to survey other cells of the body for signs of infection. T cells must strike a fine balance – failure to detect evidence of pathogens may result in lethal infection whereas unnecessary activation is a leading cause of autoimmune disease. This balance is achieved at a cell-cell communication interface called the T cell immunological synapse.

This project aims to understand the composition-function relationship of the plasma membrane at the T cell immunological synapse and how the composition of the membrane may be manipulated to effect specific cellular outcomes. The project is open-ended and will employ a variety of cutting-edge interdisciplinary approaches. There are 3 main goals:

  1. To understand the composition of the membrane during T cell activation. We will use biochemical methods – subcellular fractionation as well as lipid mass spectrometry to determine which constituents are up or down regulated at synapse membranes. Advanced fluorescence microscopy will be used to map key molecules with sub-micron resolution as well as map membrane physical properties such as fluidity and thickness.
  2. To determine methods of manipulating T cell immune synapse membrane composition. Here, we will use genetic tools – CRISPR as well as small-molecule pharmacological agents to address the metabolic pathways maintaining membrane homeostasis with the aim of creating bespoke membrane compositions and membrane biophysical properties.
  3. To determine the effect of novel membrane compositions on T cell function. We will monitor markers of the activation of T cells – proliferation, migration, IL-2 production, with different physiological stimuli to determine whether the delicate balance of the threshold for T cell activation has been changed. In this way, we ultimately aim to determine whether manipulations to the membrane composition can be exploited as a means of manipulating the T cell immune response with implications for human health.

The student will learn and employ a variety of interdisciplinary approaches including molecular biology and CRISPR-Cas9, mass-spectrometry, proteomics and lipidomics, fluorescence microscopy and immunological assays. The work sits at the interface of metabolomics, cell biology, biophysics, immunology and medicine.

References:

  1. Dustin, The Immunological Synapse, Cancer Immunol. Res. 2015.
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4692051/
  3. Harder, The T cell Plasma Membrane Lipid Bilayer Stages TCR-Proximal Signalling Events. Frontiers in Immunology 2012.
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3342336/

BBSRC Strategic Research Priority: Understanding the Rules of Life: Immunology

    Techniques that will be undertaken during the project:

    • Molecular biology, cloning, CRISPR-Cas9, PCR
    • Fluorescence microscopy – confocal, live-cell imaging, quantitative image analysis
    • Immunological assays via brightfield imaging, Western blot, ELISA
    • Proteomics and lipidomics – sub-cellular fractionation, interpretation of mass spectrometry facility data

    Contact: Professor Dylan Owen, University of Birmingham