Are the pathways that protect tissues from mechanical stress lost in ageing?

The defining qualities of our cells - their physical features and function - can be determined by their surroundings, but the tissue environment can be demanding. Just as our muscles regenerate and are conditioned by exercise to maintain health, our cells have developed mechanisms to protect against damage induced by mechanical stress. A fundamental response to stress is the production of chaperone proteins within our cells. These molecular machines act to limit and reverse damage by refolding the proteins unwound by stress back into functional structures. However, these mechanisms are thought to deteriorate as we age. This loss of function may be compounded by other factors affecting ageing tissue. The extracellular matrix - the material in which cells are embedded - may stiffen and become fibrotic in ageing tissue, changing the ways that tissue-resident cells experience mechanical stresses. A knowledge of the pathways that enable cells to sense and respond to physical signals is therefore key to understanding the ageing process.

This project will look at how senescent cells, used as a model of ageing, respond to periods of cyclic straining in two- and three-dimensional environments. It will build on new and exciting findings from the Swift laboratory: (i) that senescent cells lose their ability to 'feel' and respond to the mechanical properties of their environments; (ii) that senescent cells also lose their ability to express protective chaperone proteins when faced with stress; and (iii) that regulation of mechano-sensitivity and chaperone expression are integral to the strain response in healthy (i.e. nonsenescent) cells. The responses of senescent cells will be compared to control cells using combinations of: microscopy, to characterise structural and morphological changes within cells; mass spectrometry proteomics, to identify, in an unbiased way, the stress-regulation pathways abrogated in senescence; and RNA-Seq transcriptomics to establish complete signalling pathways. We will also look for evidence of compromised cellular integrity, such as the accruement of DNA damage. Important pathways will be investigated in more detail by knocking down key proteins, or by expressing proteins in senescent cells to restore function.

This 'Underpinning Bioscience' project will take a multidisciplinary approach to deliver fundamental insight into the ageing process in mechanically loaded tissues. It will aim to build a holistic picture of how cells function, from a molecular level to their integration within three-dimensional environments that replicate active, living tissues. The project will deliver on the BBSRC's ENWW remit in two ways: Firstly, it will build on the Swift lab's experience in integrating complex '-omics' datasets with imaging and molecular biology methods to give a complete understanding of the underlying biology. The student will analyse samples using mass spectrometry proteomics and RNA-Seq (with support from Core Facilities), and will interpret the data with assistance from established collaborators with backgrounds in bioinformatics and statistics. Secondly, it is very much an interdisciplinary project that combines methods in molecular and cell biology with biophysics to build an improved understanding of the physiological ageing process. The student will have access to a broad range of tools in biology, physics and engineering laboratories. They will learn how to solve problems in novel ways and will be well placed to take advantage of the exciting and underexploited areas of overlap between disciplines.