title: Next-generation sequencing identifies equine cartilage and subchondral bone miRNAs and suggests their involvement in osteochondrosis physiopathology.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are an abundant class of small single-stranded non-coding RNA molecules ranging from 18 to 24 nucleotides. They negatively regulate gene expression at the post-transcriptional level and play key roles in many biological processes, including skeletal development and cartilage maturation. In addition, miRNAs involvement in osteoarticular diseases has been proved and some of them were identified as suitable biomarkers for pathological conditions. Equine osteochondrosis (OC) is one of the most prevalent juvenile osteoarticular disorders in horses and represents a major concern for animal welfare and economic reasons. Its etiology and pathology remain controversial and biological pathways as well as molecular mechanisms involved in the physiopathology are still unclear. This study aims to investigate the potential role of miRNAs in equine osteochondrosis (OC) physiopathology.Short-read NGS technology (SOLID™, Life Technologies) was used to establish a comprehensive repertoire of miRNA expressed in either equine cartilage or subchondral bone. Undamaged cartilage and subchondral bone samples from healthy (healthy samples) and OC-affected (predisposed samples) 10-month Anglo-Arabian foals were analysed. Samples were also subjected or not to an experimental mechanical loading to evaluate the role of miRNAs in the regulation of mechano-transduction pathways. Predicted targets of annotated miRNAs were identified using miRmap.
  
  
  RESULTS
  Epiphyseal cartilage and subchondral bone miRNome were defined, including about 300 new miRNAs. Differentially expressed miRNAs were identified between bone and cartilage from healthy and OC foals, as well as after an experimental mechanical loading. In cartilage, functional annotation of their predicted targets suggests a role in the maintenance of cartilage integrity through the control of cell cycle and differentiation, energy production and metabolism as well as extracellular matrix structure and dynamics. In bone, miRNA predicited targets were associated with osteoblasts and osteoclasts differentiation, though the regulation of energy production, vesicle transport and some growth factor signaling pathways.
  
  
  CONCLUSIONS
  Taken together, our results suggest a role of miRNAs in equine OC physiopathology and in the cellular response to biomechanical stress in cartilage and bone. In silico target prediction and functional enrichment analysis provides new insight into OC molecular physiopathology.
authors.affiliation: INRA, UMR1313 Génétique animale et biologie intégrative, Domaine de Vilvert, 78350 Jouy-en-Josas, France. clemence.desjardin@jouy.inra.fr.
authors.forename: Clémence
authors.initials: C
authors.lastname: Desjardin
authors.forename: Anne
authors.initials: A
authors.lastname: Vaiman
authors.forename: Xavier
authors.initials: X
authors.lastname: Mata
authors.forename: Rachel
authors.initials: R
authors.lastname: Legendre
authors.forename: Johan
authors.initials: J
authors.lastname: Laubier
authors.forename: Sean P
authors.initials: SP
authors.lastname: Kennedy
authors.forename: Denis
authors.initials: D
authors.lastname: Laloe
authors.forename: Eric
authors.initials: E
authors.lastname: Barrey
authors.forename: Claire
authors.initials: C
authors.lastname: Jacques
authors.forename: Edmond P
authors.initials: EP
authors.lastname: Cribiu
authors.forename: Laurent
authors.initials: L
authors.lastname: Schibler
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001842:Bone and Bones / Q000378:metabolism* / Q000503:physiopathology; D002356:Cartilage / Q000378:metabolism* / Q000503:physiopathology; D059014:High-Throughput Nucleotide Sequencing; D006734:Horse Diseases / Q000235:genetics* / Q000503:physiopathology; D006736:Horses / Q000235:genetics*; D035683:MicroRNAs / Q000235:genetics*; D058977:Molecular Sequence Annotation; D055034:Osteochondrosis / Q000235:genetics* / Q000503:physiopathology; D017423:Sequence Analysis, RNA; D016474:Weight-Bearing
chemical_list: D035683:MicroRNAs