Unravelling mechanisms of Endothelial Cell Senescence

Aims:  Through age-related increases in oxidative stress, endothelial cells (ECs) become irreversibly senescent and accumulate in vasculature over time. Accumulation of senescent ECs triggers endothelial dysfunction through senescence-associated secretory phenotype (SASP). This study will explore the relationship between oxidative stress and EC senescence with particular reference to activity of p38MAPK/NF-kB signalling pathway and changes in the composition of SASP.

Background: Ageing affects structure and function of vascular system. Endothelial dysfunction (ED) constitutes the main phenotype that promotes age-dependent changes in vasculature. Endothelium covers the inner surface of blood vessels and regulates vascular tone, permeability, angiogenesis, coagulation and inflammation by synthesising many vasoactive compounds. Accumulation of senescent ECs in vasculature is emerging as an important stimulus for the development of ED. Oxidative stress, emerging from an imbalance between the activities of pro- and anti-oxidant enzymes, represents a key factor for the senescence of ECs during ageing process. Increasing evidence suggest that acquisition of an irreversible SASP and subsequent secretion of various soluble factors such as cytokines, chemokines, growth factors and matrix metalloproteases may also contribute to the appearance of ED. Activation of p38MAPK/NF-kB pathway appears to be the main stimulus leading to adoption of SASP. Inhibition of NF-kB, a transcription factor that regulates the release of inflammatory cytokines, has been shown to improve endothelial function in healthy older adults to the levels observed in young controls by reducing oxidative stress, confirming the interdependence amongst ageing, oxidative stress and inflammation.

Experimental methods: Using a number of highly sophisticated molecular biological techniques, including siRNA technology and cDNA electroporation, this study will firstly investigate the correlation between oxidative stress and ageing at EC level (senescence). ECs that display shortened telomere length, reduced proliferative and tubulogenic potentials and stain about 70% positive for S-b-galactosidase and g-H2AX activities will be regarded as senescent. To assess how the major components of SASP are affected by EC senescence, the profile of a large number of secreted angiogenic factors and inflammatory cytokines will also be explored in senescent EC cultures using a series of sophisticated methodologies, including proteome profiler assays and single cell RNA sequencing. Functional implications of EC senescence on vasculature will be examined through use of an in vitro model of human BBB in the absence or presence of structurally and functionally distinct senotherapeutics targeting oxidative stress, p38MAPK and NF-kB pathways.

Expected outcomes and impact: Data generated will demonstrate the molecular mechanisms involved in senescence of ECs and will inform the design of future studies focusing on healthy ageing and age-related disease.

How to apply

International students only

Please email a recent CV along with a cover letter to Dr Ulvi Bayraktutan.