Joe Swift, PhD
Healthy cell behaviour is dependent on signalling from the cellular environment. Stem cells, for example, can interpret matrix stiffness cues in deciding whether to differentiate or remain quiescent. Cells in mature tissue must also be appropriately regulated to meet the mechanical demands of their surroundings, with cells in active tissue requiring more robust cellular structures in the cytoskeleton and nucleus. How cells receive and decipher mechanical inputs, by feeling the compliance of their surroundings or by being subject to deformation, is a key area of research in the field of mechanobiology. The group is interested in how these physical inputs are transmitted from matrix to cell and how they are transduced into molecular signalling in the nucleus. We are keen to understand how these pathways change during the ageing process, when our tissues stiffen and cellular capacity to repair and regenerate is diminished. In vitro models of ageing will be developed based on characterization of primary tissues. We will also investigate the role of chaperone proteins – guardians against protein damage whose response is thought to diminish in ageing – in maintaining the structural integrity of the cell. These problems will be tackled using an ‘-omics’ toolkit for mechanobiology, allowing the study of protein regulation, changes in protein-protein interactions and mechanically-sensitive changes in protein conformation.
Mechano-transduction. The mechanical inputs that cells interpret are a combination of force and geometry over length scales of nano- to micro-metres, but in all cases signals are eventually transduced through to changes at a molecular level. To give the required specificity of action, for example in turning a particular genetic program on or off, these molecular-scale signals must be regulated with exquisite spatial and temporal accuracy. The cartoon above summarizes the main mechano-sensing pathways present in tissue. Spatial and temporal control are achieved through two recurring motifs: (i) force-mediated regulation of activity through chemical modification; (ii) force-mediated regulation of activity by location or conformation. In many cases these processes occur in concert, for example, a post-translational modification (PTM) such as phosphorylation may alter the mobility of a protein, or a change in protein conformation may regulate its susceptibility to modification.
Molecular mechanobiology. Following work by Discher and co-workers (see, for example Swift et al. Science, 2013), the laboratory will continue to develop ‘-omics’ methods to study force sensitivity in molecular processes: (i) profiling changes to transcript and protein levels can help illuminate the regulatory pathways that respond to mechanical input. (ii) immuno-precipitation can be used to enrich target proteins for analysis by mass spectrometry (MS) proteomics, allowing identification of PTMs and binding partners. (iii) Sophisticated labeling methods can also allow stress-induced changes in protein conformation to be quantified (Johnson et al. Science, 2007). Proteomic profiling will be used in combination with a range of microscopy methods in order to give spatial resolution within cells and tissue.
Research at Manchester. The laboratory benefits from a wealth of experience at the Wellcome Centre for Cell-Matrix Research and contributes to a number of the Centre’s key research themes: understanding the mechanical aspects of cell-matrix signalling; the ageing of matrix; and how the environment can direct cell fate. The group is also keen to foster new collaborations with the wider research community.
Recent key publications
Swift J & Discher DE. The nuclear lamina is mechano-responsive to ECM elasticity in mature tissue. J Cell Sci (2014) 127 (14) 3005-3015.
*Swift J, *Ivanovska IL, Buxboim A, Harada T, Dingal PCDP, Pinter J, Pajerowski JD, Spinler KR, Shin J-W, Tewari M, Rehfeldt F, Speicher DW, Discher DE. Nuclear lamin-A scales with tissue stiffness and enhances matrix-directed differentiation. Science (2013), 341 (6149), 1240104.