Tissue dependent structure of fibrillin microfibrils

Fibrillin forms fibres that are important for providing our connective tissues with elasticity such as large blood vessels like the aorta, lungs and skin. Symptoms of ageing associated with a loss of elasticity, for example skin wrinkles, hypertension and eye deterioration, have been linked to degradation of fibrillin. Fibrillin binds to growth factors outside of the cell creating a tissue storage depot. This storage is needed for correct development, repair and maintenance of our tissues, such as the heart, lungs and skin. Binding to fibrillin allows cell signalling to occur correctly to maintain normal tissue structure and function, and are essential in human embryo developmental. Our limited knowledge regarding the structure of fibrillin fibrils presents a major obstacle to understanding their function. The main aim of our work therefore is to understand the structure of the fibrillin fibrils which we believe will allow us to locate the growth factor binding regions, as well as sites important for elastic fibre formation and where cells bind to fibrillin. We will determine what differences occur between fibrillin fibrils from different elastic tissues such as blood vessels and eyes. Finally, we will discover what differences occur in fibrillin fibrils produced at different stages of development, i.e. at birth and in adulthood. Together this will lead to an understanding of how fibrillin fibrils change with tissue type and age and how their structure underpins their important roles in tissue assembly, elasticity and maintenance.

Understanding the structure and composition of fibrillin, whose function is to maintain tissue elasticity could have significant health and economic benefits to the UK. Stiffening of the blood vessels and valves of the heart are major causes of heart disease which affects more than 6 million citizens in Europe each year. Heart disease has a huge economic impact, due to the high medical costs and work disability. In the eye, losing elasticity effects the ability to bend the lens (accommodation) which leads to the loss of up-close vision with age. This can be improved by wearing glasses but does not correct completely for this age-related deterioration in vision. Our research findings could be of future interest to the pharmaceutical industry in developing treatments to maintain the elasticity of these tissues and in engineering of replacement biomaterials. Effective treatment would significantly improve the quality of life of an ageing population.

Fibrillin microfibrils are essential components of most extracellular matrices (ECM). They form a template for elastin deposition and a platform for microfibril-elastin binding proteins to interact essential for the function of large blood vessels, skin and lungs. In addition to their structural role, microfibrils mediate cell signalling via integrin and syndecan receptors, and sequester growth factors within the ECM providing a tissue store which is critical for homeostasis and remodelling. Elastic fibre proteins are used to coat polymer scaffolds to engineer biocompatible materials. However, a lack of knowledge of the molecular structure of fibrillin microfibrils limits our understanding of the spatial location and proximity of functional regions of the fibrillin molecule. Therefore the aim of this research is to understand the structure and molecular organisation of fibrillin microfibrils, and how microfibrils differ between different tissue types and with developmental stage.

We will use cryo-EM with image analysis to determine the 3D structure of fibrillin-1 microfibrils. Mutant fibrillin microfibrils from the GT8 mouse model will also be imaged by EM, AFM and STEM mass mapping to locate regions of the fibrillin molecule and distinguish between packing models. This will allow modelling of the individual domains of fibrillin to the 3D structure. Microfibrils from different tissue sources including those elastin-rich and devoid of elastin will be imaged to determine differences in their structure and their composition analysed by mass spectrometry. Finally, microfibrils from newborn and adult tissues will be compared to look at changes upon microfibril maturation. Given the key role played by microfibrils as mediators of tissue homeostasis any structural differences are likely to impact on tissue ageing and the ability of tissue engineered constructs to recapitulate native tissue function and may provide new opportunities for future therapeutic strategies.

We anticipate that the results gained from this study will be of both significant intellectual and clinical benefit as it will deliver high-quality biochemical research on a fundamental elastic structures in mammalian connective tissues. In particular, this work is relevant to the BBSRC Strategic Research Priority "Healthy ageing across the lifecourse" because of the vital roles fibrillin plays in maintaining the normal structure and function of the skin, heart, lungs and eyes.

This work will provide novel insights into a molecular mechanism relevant to tissue assembly, in particular elastic tissues. This proposal is to undertake basic science underpinning the regulation of homeostatic events in tissues, but our research findings could be of future interest to the pharmaceutical industry in developing treatments to maintain the elasticity of tissues. We will utilise the Faculty Research Support Managers, part of whose remit is to facilitate interactions with industry and University of Manchester Intellectual Property (UMIP) to identify any commercialisable research.

The results of this study will be of academic benefit to a range of research communities including connective tissues, development, growth factor and structural biology research communities as outlined in the academic beneficiaries section. We will disseminate the results of this research through participation at relevant conferences and through publications in peer-review journals as outlined in the previous section. We are also committed to public engagement in science. For example, the Faculty of Life Sciences (FLS) is active in promoting the communication of science to the public (in which the applicants group participates). Initiatives include reporting research breakthroughs in the local, national and international press via the Faculties Media Relations Office and schools outreach work (e.g. curriculum enrichment in the form of career advice, practical classes, and workshops). In this regard, the electron microscopy facility in FLS hosts regular visits from schools for pupils in years 11-13 and the EM facility runs tours during the annual Faculty of Life Sciences Community Open Day in which all lab members participate.

Training and development of Alan Godwin, the RA, in new techniques will enhance his research career. FLS has embraced training and career development for all categories of staff and current support available to PDRAs for professional development includes monthly training bulletins, one-to-one advice and guidance and bespoke workshops. Recent workshops have included: "Planning a Fellowship", "Grant Reviewing", "Academic CV Writing" and a "Careers Day". These workshops have aimed to develop a range of skills including career planning, networking, project management, team working, critical peer review, communication and self awareness.