Modulation of the Wnt signalling in the articular cartilage: is it all about the dose?

This project aims to investigate key mechanisms maintaining the health of the articular cartilage, the tissue covering the edges of the long bones in the joint, allowing a smooth sliding of the bones while we move. The articular cartilage is affected by severe structural damage during the development of a disease called osteoarthritis. Osteoarthritis affects millions of people worldwide. People affected suffer chronic pain and disability with a severe decrease in the quality of life. The only available treatment is pain relief until cartilage damage is so severe that surgery is required. Surgery usually consists of surgical removal of the joint and its replacement with a prosthetic. By understanding the mechanisms keeping the cartilage healthy, we could design new drugs to re-establish the cartilage in cases where it is lost or damaged.
We already have evidence showing that a class of proteins called Wnts (pronounced Wenz) are important to maintain cartilage integrity. Thus, the final goal of this application is to understand how these Wnts work. We have three aims: 1) to clarify which other proteins might work with the Wnts within a group of receptors, called frizzled receptors, which are present on cartilage cells; 2) to identify whether very small molecules called microRNAs can modify the function of the Wnts from within the cell; 3) determine whether the function of the Wnts is altered during OA development and whether re-establishing their original activity could be exploited in the future via development of a drug as a therapeutic treatment.

Despite its strong association with osteoarthritis (OA) development, Wnt-signalling has been an elusive target for the generation of disease modifying drugs. Researchers so far have in fact been unable to untangle the components leading to the anabolic effects of the signalling from the pro-catabolic ones. Our previous and most recent data suggest that a tight balance in the activation levels of two branches of the signalling, the Wnt/beta-catenin and the Wnt/Calcium Calmodulin Kinase (CaMKII) cascades, is required to maintain cartilage homeostasis and avoid OA development. In this grant we aim to investigate the molecular mechanisms activating the pathways and keeping their balance, to understand how cartilage physiology is maintained and how to re-establish it to avoid OA development and/or halt disease progression. More in detail, we will be investigating (i) how the specificity of receptor-ligand interaction is involved in the activation of the Wnt/beta-catenin and of the Wnt/CaMKII pathways (ii) which micro-RNAs are involved in modulating Wnt-led signal transduction, (III) whether the manipulation of ligand/receptor interaction and of the key micro-RNAs can influence the chondrogenetic and pro-regenerative properties of the articular chondrocytes.
The project builds up on our preliminary data and toolsets (microarray analysis of Wnt beta-catenin dependent targets in articular chondrocytes and wide expertise in in vitro phenotype analysis of chondrocytes and in vivo models of chondrogenesis) and on ongoing collaborations with world-class pharmacologists and experts in the field of osteoarthritis. The grants aligns with MRC Strategic Aim 1 (Picking research that delivers-Theme 1) and Aim 4 (Supporting Scientists).

Our research will improve our understanding of the mechanisms maintaining articular cartilage health, leading to positive impacts both in the UK and abroad. This research falls well within the remit of the Molecular and cellular medicine board strategy to support regenerative medicine-related projects.
HEALTH and WELLBEING
Osteoarthritis (OA) is a leading cause of disability worldwide. Only in the UK, 8.75 million people aged 45 and over are currently seeking treatment for OA. OA-associated joint damage impairs mobility, compromises patients' independence and induce chronic pain. No pharmacological treatment can revert the joint to its healthy state or at least stop disease progression. Invasive reconstructive surgery is the ultimate option for the most severe cases translating into huge socio-economic costs: up to 2.5% of the GDPs in the developed countries are spent in OA-associated costs.
Our proposal has an ultimate goal to understand how joint homeostasis is maintained in physiological conditions and the key molecular drivers of these mechanisms. We believe that these could be targeted pharmacologically to develop new disease modifying drugs ultimately improving the quality of life of million people worldwide, avoiding the need of invasive surgeries as well as hospitalisation associated costs and possible post-surgical complications.

PHARMACEUTICAL INDUSTRY
As mentioned above, osteoarthritis patients represent a huge slice of the pharmaceutical market, both human and veterinary. As well as in human, in fact, 30% of the dogs and 20% of horses' owners seek medical attention for their pets because of OA. As molecular mechanisms leading to OA seems to be preserved across species, our discoveries could be developed in collaboration with the private sector across human and veterinary markets having a long term impact on the UK and worldwide market. This would create jobs and would strengthen the UK's competitive advantage in this sector.

PROVISION OF SKILLED PEOPLE IN THE WORKFORCE
The burden of musculoskeletal disease is predicted to increase: by 2050, 130 million people will be affected. The PDRAs who will employed on this grant will be trained in a highly specialised scientific skillset and provided broadly transferrable skills in oral and written communication, public engagement and interdisciplinary collaborations. This will prepare them for a career as future scientific leaders, or in teaching, policy or public engagement, which are ever-more important as the awareness and importance of the musculoskeletal conditions grows.