Molecular mechanisms coupling matrix rigidity to DNA damage in smooth muscle

Our blood vessels are flexible and this gives them the ability to expand and contract in response to changes in blood pressure. This flexibility is important for healthy ageing. The aorta is a large elastic artery that carries blood away from the heart. The stiffness of the aortic wall determines how flexible the aorta is. The aortic wall contains elastic and non-elastic proteins and the balance between these determines the flexibility of the aortae. Healthy aorta expands as blood moves through the vessel. This results in stretching of the aortic wall. Stretching causes muscle cells in the aortic wall to generate force and contract.

As we age, our aorta loses this flexibility. Over time, the elastic aortic wall components become damaged and the non-elastic components accumulate. This loss of flexibility is a hallmark of unhealthy ageing and places extra demand on the heart that increases the risk of heart failure. Decreased flexibility is driven by increased stiffness of the aortic wall. Our understanding of how increased stiffness affects the aortic wall muscle cells remains extremely poor.

The central aim of this proposal is to understand how increased stiffness affects that ability of the aortic muscle cells to contract. Our understanding of this question has been hindered as most laboratories grow cells on plastic or glass, which are extremely stiff. We grow the aortic muscle cells on a special material that mimics the stiffness of the healthy and unhealthy aortic wall.

We will investigate how unhealthy aortic wall stiffness affects muscle contraction. The findings from these studies will advance our understanding of how increased stiffness affects the aortic wall muscle cells. These results will provide new mechanisms that will inform on future therapies aimed at increasing vascular health.

Vascular compliance, the ability of blood vessels to change shape in response to changes in blood pressure, is essential for healthy ageing. Vascular smooth muscle cells line the blood vessel wall and healthy aortic compliance stretches VSMCs, opening stretch activated channels that initiate VSMC contraction. However, as we age, our blood vessels lose this ability and vascular compliance decreases. Loss of compliance is driven by 1) increased vessel wall rigidity and 2) increased VSMC stiffness.

It remains unknown how changes in blood vessel wall rigidity affect the ability of VSMCs to contract. The mechanisms that augment VSMC stiffness also remain elusive. In other cell types, increased cellular force generation and stiffness result in cellular damage. We hypothesise that matrix rigidity will induce aberrant contraction, promote damage to healthy VSMCs, increase VSMC stiffness and further decrease aortic compliance. This proposal aims to answer the following questions:

How does matrix rigidity affect VSMC contraction?

Does altered contraction harm VSMCs in rigid environments?

Does altered contractile function enhance VSMC stiffness in rigid environments?

This proposal will identify novel mechanistic differences between VSMC contraction on physiological and pathological matrix rigidity. These findings will provide novel mechanistic insight into the interplay between matrix rigidity, VSMC health and VSMC stiffness. Therefore, this proposal will also impact on therapies designed to extend and promote healthy ageing.

This is a fundamental science project which will investigate how matrix rigidity affects VSMC contraction. This project sits firmly in the BBSRC specific priority of 'Health ageing across the life course'. The outcomes will provide a clearer understanding of the relationship between matrix rigidity, VSMC contraction and VSMC dysfunction. This project will significantly advance our understanding of the balance between matrix rigidity and VSMC stiffness. We will identify novel pathways that promote VSMC dysfunction that will be of therapeutic interest.

We will describe novel VSMC stiffness pathways that are only activated in rigid environments. Therefore, these findings will have potential industrial impact. We currently lack both targets and reagents to therapeutically restore aortic compliance. VSMC stiffness contributes to decreased vessel compliance, therefore our findings will provide novel targets and potentially reagents to increase aortic compliance. The findings will also stimulate interest in the cardiovascular preclinical field and healthcare professionals as we will identify novel mechanisms that contribute to cardiovascular disease.

To increase the visibility of this research to the public we will use podcasts and videos as an accessible medium. We have created a Vascular Research Twitter account (@WarrenLabUEA) that has brought together basic scientists, clinical researchers and the public. This allows us to engage a wide audience simultaneously. Podcasts and videos of the research project will be added to this account, as well as Dr Warren's School of Pharmacy webpage and the School of Pharmacy Facebook page. Podcasts and videos will allow us to explain the concepts of our research and answer questions like 'why this research is important?'

We regularly tweet about published papers, our attendance at scientific meetings etc. We will also interview our collaborators about why their expertise enhances this research. We will interview speakers (invited to visit UEA) related to this project and experts in this field (during national and international conferences) about how these studies are advancing human knowledge and healthcare. Our will be advertised at invited talks and at conferences attended by Dr Warren and the PDRA and at all our events below.

The research in this proposal will generate microscopy videos and images. As a visual approach to increase awareness of this proposal, we will submit images and/or movies to the British Society of Cell Biology scientific image competition, an annual national image competition aimed at expanding the impact of images generated through cell biological research. We will also use images and movies to illustrate our Twitter account. These visual approaches will allow the reader to greater understand the concepts of the research.

Generating interest and excitement in the next generation of scientists is essential for future scientific advancement and excellence. A key impact aim of this proposal is to engage school children and the general public. To increase the visibility of the research in the local area of Norwich, we will volunteer to run a demonstration at the Norwich Science Festival. This event is held once a year. The audience ranging from school children to scientific experts, so the content has to be clear and understandable for the mixed public audience. We have been liaising with the UEA school outreach team and plan to target A-level students. We have devised 5 fun tasks aimed at understanding the role of physics in biological research. These tasks range from passing water through rubber pipes of different dimensions (to represent blood vessel ageing), to using springs and elastic bands, to understand elasticity and matrix stiffness. Several of these tasks were piloted at our School of Pharmacy Applicant days, where sixth form students who have applied to our School visit to learn more about us.