Abstract
Introduction
The COL5A1 gene encodes for the α1 chain of type V collagen, a minor fibrillar collagen that is an important regulator of collagen fibrillogenesis. Several polymorphisms, including rs12722 (C/T), within the 3′-UTR of COL5A1 are associated with chronic Achilles tendinopathy and other musculoskeletal soft tissue injuries as well as exercise-related phenotypes. It is hypothesised that polymorphisms within the 3′-UTR regulate the amount of the α1(V) chain synthesised and type V collagen production. This in turn influencing the mechanical properties of tendons and other musculoskeletal soft tissues. In our laboratories, two major functional forms, namely the T- and C-allelic forms of the COL5A1 3′-UTR, were identified and associated predominately with severe chronic Achilles tendinopathy and healthy asymptomatic control individuals, respectively.
Materials and Methods
To further investigate the functional differences between the two major 3′-UTR functional forms as well as to start mapping the regions which are responsible for the tendinopathic phenotype, skin biopsies from donors having a known genotype at rs12722 and primary fibroblast cell lines were established in order to quantify COL5A1 and COL1A1 expression levels in a pilot study. Lastly, in preliminary RNA EMSAs, biotinylated C- and T-allelic RNA probes for a specific 57bp functional region within the 3′-UTR were incubated with either fibroblast nuclear or cytoplasmic protein extracts to investigate putative distinguishing RNA:RBP complex formation.
Results
An overall higher relative mRNA expression of both COL5A1 (p<0.001) and COL1A1 (p=0.0015) were observed in primary skin fibroblasts from donors having a rs12722 TT genotype compared to donors with a CC genotype. A unique RNA:RBP complex was also identified with the C-allelic probe.
Discussion
These novel results have important implications for our understanding of the proposed role of type V collagen in the aetiology of tendon and other musculoskeletal soft tissue injuries, as well as, other exercise-related phenotypes.
