Dr Jason King
Advanced Vice-Chancellor’s Fellow
Room: D09 Florey building
The main focus of the laboratory is to understand how cells perform macropinocytosis – the bulk capture of extracellular fluid. This plays important and distinct roles in diverse cell types such as macrophages, dendritic cells and neurons, by allowing cells to sample their environment and regulating membrane turnover. However macropinocytosis also allows cancer cells to scavenge the extracellular nutrients required to support their growth, and provides a route for pathogens and prions to enter host cells.
The diverse importance of macropinocytosis has only recently become clear, and both the formation and maturation of macropinosomes is poorly understood. My laboratory is thus trying to answer two fundamental questions:
Please see our personal lab website for more information on our work
Autophagy and lysosomal degradation pathways
In collaboration with Cecile Perrault (Mechanical engineering), and Paul Evans (Medical School) we are now extending these studies to physiologically relevant cells and tissues. This will further our understanding of this pathway, and determine the role of mechanically-induced autophagy in cellular homeostasis.
Our primary experimental system is the soil amoeba Dictyostelium discoideum. This allows us to use powerful molecular techniques to dissect autophagy in a simple model system. In addition, as Dictyostelium exclusively use phagocytosis and macropinocytosis to take up nutrients, they are an excellent model for phagocytic immune cells. The ease with which Dictyostelium can be genetically manipulated allows us to circumvent the experimental limitations of macrophages and neutrophils, which we are currently exploiting to understand both infectious disease and fluid uptake, in collaboration with Simon Johnston.
Undergraduate and postgraduate taught modules
Postgraduate studentship opportunities
1. Investigating the physics of phagocytosis
Supervisor 2: Dr Andrew Parnell
Funding status: Awaiting funding decision/Possible external funding
To effectively prevent infections, phagocytic cells of the immune system need to efficiently engulf microbes of widely varying size, shape and biomechanical properties. This is achieved by a process known as phagocytosis.
How phagocytic cup formation is spatially organized, and adapts to engulfing particles of different geometries and stiffness is however poorly understood. This project will directly address this, providing insight into both fundamental mechanisms of phagocytosis and immune cell function.
These important questions will be answered using a cross-disciplinary approach, combining polymer physics, genetics and cell biology. This project will initially generate particles as bacterial analogues, controlling their size, shape, stiffness and surface ligands/chemistry. This will be combined with the use of the amoeba Dictyostelium discoideum as a model phagocytic cell that allows us to genetically manipulate the cell and image particle uptake at high resolution.
This novel approach will allow a detailed analysis of how different particles are engulfed and modeling of the forces applied in a system where both the cell and particle can be controlled. Evasion of phagocytosis is a key mechanism employed by pathogens to avoid the immune system. Understanding the mechanics of phagocytosis in greater detail than previously possible will therefore help us better understand how infections are suppressed, and help improve our approaches to combatting antimicrobial resistance.
This is an interdisciplinary project and will provide training across the physical and life sciences including polymer physics, surface chemistry, microscopy, genetics and cell biology. Candidates from either a physics, chemistry or biological background are all potentially suitable - given an open mind, enthusiasm and the ability to learn new skills. More information on the King laboratory can be found at www.king.group.shef.ac.uk The Parnell laboratory website can be found at http://www.polymer-physics.group.shef.ac.uk/index.php/Dr_Andrew_Parnell
Keywords: Biophysics, Cell Biology / Development, Immunology, Microbiology, Molecular Biology, Materials Science, Biophysics
2. Regulation of antimicrobial activity by phagosomal phosphoinositides
Funding status: This studentship is directly funded by an award to Dr. King from the Royal Society. Funding is for 4 years and covers: (i) tax free stipend at the standard Research Council rate (currently £14,553/year for 2018-2019), (ii) research costs, and (iii) tuition fees at the UK/EU rate.
The capture and killing of invasive microorganisms by phagocytic immune cells is critical for the body’s defence against pathogens. It is therefore essential for professional phagocytes such as macrophages and neutrophils to rapidly and efficiently kill their prey to prevent the establishment of infections and disease. Multiple mechanisms are used to achieve this with phagosomes quickly becoming acidified and acquiring reactive oxygen species, antimicrobial peptides and acid hydrolases following engulfment. The timely and regulated delivery of these components is vital to protect the host from intracellular pathogens, but is still incompletely understood.
Phosphoinositide lipids (PIPs) are key regulators of vesicular trafficking. The interconversion of PIP species and subsequent recruitment of specific effectors provides a powerful mechanism to regulate membrane dynamics and is critical during phagosome maturation. Of the PIPs, PI(3,5)P2 is one of the least well understood due to its low abundance and the lack of reliable reporters. We have recently found that blocking PI(3,5)P2 synthesis by disrupting the PI5-kinase PIKfyve dramatically reduces proteolysis and killing of phagocytosed bacteria, allowing the pathogen Legionella pneumophila to survive and grow unrestrained.
Mechanistically however, the role of PI(3,5)P2 during phagosome maturation and killing remains unclear. The aims of this project are therefore to:
1) Understand the dynamics and roles of PI(3,5)P2 during phagosome maturation and bacterial killing.
2) Determine the mechanisms regulating phagosome maturation in response to bacteria
This project will use the amoeba Dictyostelium discoideum as a model system. Like immune cells, Dictyostelium are professional phagocytes but hunt and kill bacteria for food. Phagocytosis is highly conserved and this system allows us to combine genetic manipulation and high-resolution live imaging not possible with immune cells. We are then able to directly translate our work to a number of infectious diseases. This studentship will provide training in a wide range of techniques including live super-resolution light microscopy, proteomics, biochemistry and molecular biology. We are therefore seeking a talented and enthusiastic individual with interests in infectious disease and cell biology. Please see our website (http://king.group.shef.ac.uk) or contact directly for more information.
Keywords: Cell Biology / Development, Immunology, Microbiology, Molecular Biology
For informal enquiries about these projects or the application process, please feel free to contact me:
To find out more about other departmental projects and how to apply see our PhD opportunities page:
- Buckley CM, Gopaldass N, Bosmani C, Johnston SA, Soldati T, Insall RH & King JS (2016) WASH drives early recycling from macropinosomes and phagosomes to maintain surface phagocytic receptors. Proc Natl Acad Sci U S A, 113(40), E5906-E5915. View this article in WRRO
- Gerstenmaier L, Pilla R, Herrmann L, Herrmann H, Prado M, Villafano GJ, Kolonko M, Reimer R, Soldati T, King JS & Hagedorn M (2015) The autophagic machinery ensures nonlytic transmission of mycobacteria. Proceedings of the National Academy of Sciences, 112(7), E687-E692.
- Calvo-Garrido J, King JS, Muñoz-Braceras S & Escalante R (2014) Vmp1 Regulates PtdIns3P Signaling During Autophagosome Formation in Dictyostelium discoideum. Traffic, 15(11), 1235-1246.
- King JS, Gueho A, Hagedorn M, Gopaldass N, Leuba F, Soldati T & Insall RH (2013) WASH is required for lysosomal recycling and efficient autophagic and phagocytic digestion. Molecular Biology of the Cell, 24(17), 2714-2726. View this article in WRRO
- King JS, Veltman DM & Insall RH (2011) The induction of autophagy by mechanical stress. AUTOPHAGY, 7(12), 1490-1499.