Structure and regulation of the chordin-BMP inhibitory complex

Lead Research Organisation: University of Manchester
Department Name: Life Sciences

Abstract

The bone morphogenetic proteins (BMPs) are powerful 'growth factors' which are messenger molecules that can direct processes in cells, for instance telling them how much to grow or even whether they should live or die. These processes are crucial in maintaining normal tissue structure and function, and for essential processes in early embryonic development. The BMPs were first discovered for their ability to stimulate new cartilage and bone formation and they do this by manipulating cellular behaviour. The action of BMPs is controlled by inhibitors found outside of the cell and correct regulation by inhibitors is required for correct development. The inhibitors are large proteins that bind to the BMPs, thereby preventing them from interacting with their receptors and sending a message to the cell. We are interested in one BMP inhibitor, chordin, which is necessary for correct embryonic developmental but there are currently no details of the chordin-BMP complex. Our limited knowledge regarding BMP inhibitors and the complexes they form presents a major obstacle to understanding BMP function. The main aim of our work therefore is to understand the structure of the chordin-BMP complex which we believe will lead to an understanding of how BMP regulation occurs. We will determine the shape of chordin when bound to BMP and how chordin releases BMP. Finally, we will discover how the BMP receptor competes with chordin to interact with BMP and how these interactions underpin their important roles in tissue assembly and embryo development. Understanding these molecular events preceding cartilage formation could have significant health and economic benefits to the UK. Joint diseases such as osteoarthritis and rheumatoid arthritis affect more than 10 million people in the UK. The diseases have a huge economic impact, due to the high medical costs and work disability. Cartilage heals poorly after damage and BMPs may be useful therapeutically to stimulate healing of damaged cartilage. Our research findings could be of future interest to the pharmaceutical industry in developing future treatments to modulate cartilage deposition. Effective treatment for cartilage damage would significantly improve the quality of life of an ageing population.

Technical Summary

The bone morphogenetic proteins (BMPs) are powerful growth factor signalling molecules in the extracellular matrix. BMPs play important roles at multiple stages of skeletal development, from early patterning to regulation of chondrocyte proliferation and maturation in the growth plate. Extracellular regulation of BMPs is essential for correct development and is of therapeutic interest in relation to a broad range of pathologies including cancer, vascular disease and arthritis. Large extracellular proteins form inhibitory complexes with these growth factors, thereby preventing receptor activation but the molecular details of these complexes are unknown. One such regulator, chordin, acts by binding to BMPs thereby preventing their association with BMP receptors on the cell surface. The lack of knowledge regarding BMP inhibitors and the complexes they form presents a major hurdle to understanding BMP function. This understanding is urgently needed as BMPs are of therapeutic interest in the repair of damaged cartilage and fracture healing. The main aim of our work therefore is to understand the structure of the chordin-BMP inhibitory complex leading to an understanding of how BMP regulation via chordin inhibition is controlled in tissue assembly and developmental patterning. Specifically, we will determine the shape of the chordin-BMP inhibitory complex and define any chordin conformational change upon BMP binding; we will determine the mechanism of BMP-release from the inhibitory complex following chordin cleavage by proteases; and determine how the BMP receptor competes for binding with the inhibitory complex as chordin is cleaved. We will use a multi-technique approach of structural, biochemical and biophysical techniques including electron microscopy, small angle X-ray scattering, BIAcore, analytical ultracentrifugation and cell signalling assays.

Planned Impact

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 process in mammalian biology. In particular, this work is relevant to the BBSRC Strategic Research Priority 'Ageing research: lifelong health and wellbeing'. This work will provide novel insights into the molecular mechanism relevant to tissue assembly, in particular cartilage formation. Bone morphogenetic proteins (BMPs) can stimulate ectopic cartilage and bone formation. Understanding these molecular events preceding cartilage formation could have significant health and economic benefits to the UK. Joint diseases such as osteoarthritis and rheumatoid arthritis affect more than 10 million people in the UK. The diseases have a huge economic impact, due to the high medical costs and work disability. Cartilage heals poorly after damage and BMPs may be useful therapeutically to stimulate healing of damaged cartilage. For example, our research findings could be of future interest to the pharmaceutical industry in developing novel inhibitors or enhancers of BMPs to modulate cartilage deposition. Understanding the molecular events preceding cartilage formation could have significant health and economic benefits to the UK and effective treatment for cartilage damage would improve the quality of life of the older population. 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 schools outreach work (e.g. curriculum enrichment in the form of practical classes, workshops and career advice) and reporting research breakthroughs in the local, national and international press via the Faculties Media Relations Office. In this regard, the electron microscopy facility in FLS has regular visits from schools. Another, recent example of such activities is a series of four open days for schools in March 2010 entitled 'Wellcome to the Matrix' in which CB was involved. Due to the range and combination of techniques required for this project, the postdoctoral researcher who will be recruited is unlikely to have skills in all the techniques described. Therefore training and development of the PDRA in new techniques will enhance their 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.
 
Description The bone morphogenetic proteins (BMPs) are powerful growth factors, crucial in maintaining normal tissue structure and function and for essential processes in early embryonic developmental. Extracellular regulation of BMPs is of therapeutic interest in relation to a broad range of pathologies including cancer, vascular disease and arthritis. Large extracellular proteins form inhibitory complexes with these growth factors, thereby preventing receptor activation. One such regulator, Chordin, acts by binding to BMPs thereby preventing their association with BMP receptors on the cell surface. We have recently shown that Chordin has a horse-shoe shaped structure that supports BMP-binding in a co-operative manner (Troilo et al., PNAS USA 2014).
Exploitation Route Joint diseases such as osteoarthritis and rheumatoid arthritis affect more than 100 million citizens in Europe. The diseases have a huge economic impact, due to the high medical costs and work disability. Cartilage heals poorly after damage and BMPs may be useful therapeutically to stimulate healing of damaged cartilage. For example, our research findings could be of future interest to the pharmaceutical industry in developing novel inhibitors or enhancers of BMPs to modulate cartilage deposition.
Sectors Healthcare

Pharmaceuticals and Medical Biotechnology

 
Description We have recently published a paper in PNAS (Troilo et al., 2014) which led to an invitation to the biannual BMP meeting held in Berlin, Sept 2014. The use of soluble BMP inhibitors has led to interest in application as biotherapeutics as BMP-2, approved for clinical use is insoluble and difficult to maintain bioactivity.
First Year Of Impact 2014
Sector Healthcare,Pharmaceuticals and Medical Biotechnology
Impact Types Societal

 
Description Gerhard Sengle Cologne 
Organisation University of Cologne
Country Germany 
Sector Academic/University 
PI Contribution Provided recombinant proteins produced by our lab for cell based activity assays.
Collaborator Contribution Cell based BMP signalling assays using our recombinant protein reagents.
Impact Publication: Nanoscale structure of the BMP antagonist chordin supports cooperative BMP binding. Troilo H, Zuk AV, Tunnicliffe RB, Wohl AP, Berry R, Collins RF, Jowitt TA, Sengle G, Baldock C. Proc Natl Acad Sci U S A. 2014 Sep 9;111(36):13063-8.
Start Year 2012
 
Description Elastin and Microfibrils Gordon Research Conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Other audiences
Results and Impact Biannual invited talk at the Elastin GRC for PI Clair Baldock since 2003. Talk facilitated discussion of the use of SAXS for other elastic fibre proteins.

Elected vice-chair of GRC for 2015 (chair in 2017).
Collaboration on SAXS of tropoelastin has led to 2 PNAS, 1 JBC and 1 Matrix Biology papers to date.
Talks led to invitation to visit two Institutions in Canada (Sick Kids Hospital, Toronto and Simon Fraser University, Vancouver) and to Shriners Hospital in Portland in 2011.
Year(s) Of Engagement Activity Pre-2006,2006,2007,2009,2011,2013,2015,2017,2019,2023
 
Description Genes to Phenotypes - A-level student workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact A-level study day organised by the Wellcome Trust Centre for Cell-Matrix Research jointly with Manchester Museum. Chris Bayley (PDRA) presented his research to the students and hosted several round robin discussions about his work, the life of a scientist and the routes into a scientific career.

no actual impacts realised to date
Year(s) Of Engagement Activity 2012
 
Description Matrix Biology Europe 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Talks and posters stimulated discussion.

Mukti Singh (BBSRC DTP PhD student) was awarded a poster prize.

After talks I was asked to talk at National Societies including the German Connective Tissues Society Meeting in Cologne in 2011 and the French Connective Tissue Society Meeting in 2012.
Led to participation in an application for a Marie Curie Sklodowska ITN network.
Year(s) Of Engagement Activity 2010,2012,2018,2022
 
Description Nuffield Bursary Scheme 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Schools
Results and Impact A-level students hosted for up to four weeks in the lab. This involved designing a project, supervising the student in the lab and helping the student write a scientific report.

More students to get involved in science A-levels.
Year(s) Of Engagement Activity 2008,2010,2012,2014
 
Description Wellcome to the Matrix 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Annual event to provide the opportunity for Key Stage 3 and 4 students from local schools in Manchester to gain insight into biological research. Each 'Wellcome to the Matrix' day encourages students to work in teams to design, create and present models of particular areas of research in which we are involved.

When surveyed after the visit more students expressed an interest in taking science GCSEs.
Year(s) Of Engagement Activity 2008,2009,2012,2013