The Molecular Basis of Human Tendon Pathology: Studying both Epigenetic and Global Gene Expression Profiles.

Abstract

Regular physical activity has a variety of health benefits, however, there is also risk of developing musculoskeletal conditions from repetitive stress, and trauma, in both athletes, and non-athletes. Tendon disorders account for 30% of musculoskeletal complaints, with tendinopathy being the most prevalent. Upper-extremity tendinopathies, such as Rotator Cuff Tendinopathy (RCT), have a high prevalence, which is around 30 – 50% of the population over the age of 50 for RCT..The definitive cause of RCT is uncertain, but it is known to be a multi-factorial disorder that can manifest through a combination of intrinsic, extrinsic, and environmental factors, including genetics and epigenetics. Genetic studies have associated a variety of variants that may have a role in RCT, but global gene expression profile studies are sparse. Additionally, the role of epigenetics, including histone modifications and DNA methylation, in RCT is unclear, and limited research currently exists relating to their role in the aetiology of RCT. Based on the aforementioned information, this thesis aimed at investigating the molecular basis of RCT, specifically looking at global gene expression profiles to identify genes, and pathways, that may have a pathological role in the development of RCT. Additionally, this thesis aimed at investigating genome-wide profiling of three histone modifications, H3K4me3, H3K27me3 and H4K20me3, as well as preliminarily looking at potential differences in DNA methylation profiles between semitendinosus hamstring (control), and supraspinatus RCT (disease) tendon tenocytes. For all studies, hamstring tendon was collected from patients undergoing surgery for routine arthroscopic anterior cruciate ligament reconstruction, and supraspinatus tendon from patients undergoing arthroscopic shoulder surgery for rotator cuff (RC) tears. For genome-wide profiling of histone modifications, 5 supraspinatus tendon samples, and 4 semitendinosus hamstring tendon samples were used for investigation using Chromatin Immunoprecipitation-Sequencing (ChIP-Seq). Furthermore, 7 supraspinatus tendon samples, and 7 semitendinosus hamstring tendon samples were used for investigation into global gene expression profiles using RNA-Sequencing (RNA-Seq). Finally, 2 supraspinatus, and 2 semitendinosus hamstring tendon samples were used to investigate preliminary DNA methylation profiles in GDF5, GDF6 and GDF7 using pyrosequencing.

Date of Award	Apr 2024
Original language	English
Awarding Institution	Coventry University University of Glasgow
Supervisor	Stu Raleigh (Supervisor), Tom Cullen (Supervisor), Neal Millar (Supervisor) & John Cole (Supervisor)