Biology subjects

Canty-Laird, E. G.

Publications and source records attributed to Canty-Laird, E. G..

3 recordsLinked to original sources

bioRxiv2023

MskAge - An Epigenetic Biomarker of Musculoskeletal Age Derived from a Genetic Algorithm Islands Model

BackgroundAge is a significant risk factor for functional decline and disease of the musculoskeletal system, yet few biomarkers exist to facilitate ageing research in musculoskeletal tissues. Multivariate models based on DNA methylation, termed epigenetic clocks, have shown promise as markers of biological age. However, the accuracy of existing epigenetic clocks in musculoskeletal tissues are no more, and often less accurate than a randomly sampled baseline model. ResultsWe developed a highly accurate epigenetic clock, Msk-Age, that is specific to tissues and cells of the musculoskeletal system. MskAge was built using a penalised genetic algorithm islands model that addresses multi-tissue clock bias. The final model was trained on the transformed principal components of CpGs selected by the genetic algorithm, which are significantly enriched for pathways terms related to the skeletal system and mesenchyme development. We show that MskAge tracks epigenetic ageing ex vivo and in vitro. Epigenetic age estimates are rejuvenated to zero with cellular reprogramming and are accelerated at a rate of 0.45 years per population doubling. Remarkably, MskAge explains more variance associated with in vitro ageing of fibroblasts than the purpose-developed skin and blood clock. ConclusionThe precision of MskAge and its ability to capture perturbations in biological ageing make it a promising research tool for musculoskeletal and ageing biologists.

cell biology↗

bioRxiv2020

Active synthesis of collagen (I) homotrimer and matrisomal proteins in Dupuytren's fibrosis

Dupuytrens disease is a common fibroproliferative disease of the palmar fascia of the hand with advanced cases treated surgically. Anti-tumour necrosis factor (TNF) injection has undergone phase 2 trials and may be effective in slowing early-stage disease progression. Here we sought to determine how new synthesis of type I collagen in Dupuytrens differs from normal palmar fascia samples and to analyse the role of TNF in aberrant collagen synthesis. Model non-fibrotic, but fibrous connective tissues, were used to analyse active type I collagen protein synthesis in development, ageing and degenerative disease, where it was restricted to early development and ruptured tissue. Dupuytrens tissue was shown to actively synthesise type I collagen, including abnormal type I collagen homotrimer. TNF- reduced COL1A2 gene expression only in the presence of serum in 2D cell culture and had opposing effects on collagen protein production in the presence or absence of serum. TNF- had only limited effects in 3D tendon-like constructs. Anti-TNF did not reduce type I collagen synthesis in 3D tendon-like constructs or prevent type I collagen homotrimer synthesis in Dupuytrens tissue. Hence, modulation of the TNF- pathway in Dupuytrens disease is unlikely to prevent the pathological collagen accumulation that is characteristic of fibrosis.

cell biology↗

bioRxiv2020

Collagen (I) homotrimer does not cause bone fragility but potentiates the osteogenesis imperfecta (oim) mutant allele

Type I collagen is the major structural component of bone where it exists as an (1)2(2)1 heterotrimer in all vertebrates. The osteogenesis imperfecta (oim) mouse model comprising solely homotrimeric (1)3 type I collagen, due to a dysfunctional 2 chain, has a brittle bone phenotype implying that the heterotrimeric form is required for physiological bone function. However, humans with rare null alleles preventing synthesis of the 2 chain have connective tissue and cardiovascular abnormalities (cardiac valvular Ehlers Danlos Syndrome), without evident bone fragility. Conversely a prevalent human single nucleotide polymorphism leading to increased homotrimer synthesis is associated with osteoporosis. Whilst the oim line is well-studied, whether homotrimeric type I collagen is functionally equivalent to the heterotrimeric form in bone has not been demonstrated. Col1a2 null and oim mouse lines were used in this study and bones analysed by microCT and 3-point bending. RNA was also extracted from heterozygote tissues and allelic discrimination analyses performed using qRT-PCR. Here we comprehensively show for the first time that mice lacking the 2(I) chain do not have impaired bone biomechanical or structural properties, unlike oim homozygous mice. However Mendelian inheritance was affected in male mice of both lines and male mice null for the 2 chain exhibited age-related loss of condition. The brittle bone phenotype of oim homozygotes could result from detrimental effects of the oim mutant allele, however, the phenotype of oim heterozygotes is known to be less severe. We used allelic discrimination to show that the oim mutant allele is not downregulated in heterozygotes. We then tested whether gene dosage was responsible for the less severe phenotype of oim heterozygotes by generating compound heterozygotes. Data showed that compound heterozygotes had impaired bone structural properties as compared to oim heterozygotes, albeit to a lesser extent than oim homozygotes. Hence, we concluded that the presence of heterotrimeric collagen-1 in oim heterozygotes alleviates the effect of the oim mutant allele but a genetic interaction between homotrimeric collagen-1 and the oim mutant allele leads to bone fragility.

physiology↗