Project description:Osteoarthritis causes pain and functional disability for over 500 million people worldwide and characterized by progressive loss of cartilage from the articulating surfaces of diarthrodial joints. Although the etiology of the disease is unknown, it is widely accepted that these degenerative changes arise from an imbalance of synthetic and degradative pathways that control cartilage extracellular matrix metabolism. Genome-wide U133A Affymetrix oligonucleotide array set was used to comprehensively investigate the expression pattern in non-osteoarthritis (normal) and cartilage obtained from OA patients undergoing knee replacement surgery. This study was undertaken to better understand the molecular basis of the disease and to provide relevant insight into phenotypical alterations and mechanisms involved in OA pathogenesis.
Project description:Objective:Osteoarthritis (OA) is the most prevalent joint disease. As disease-modifying therapies are not available, novel therapeutic targets need to be discovered and prioritized for their importance in mediating the abnormal phenotype of cells in OA-affected joints. Here, we generated a genome-wide molecular profile of OA to elucidate regulatory mechanisms of OA pathogenesis and to identify possible therapeutic targets using integrative analysis of mRNA-sequencing data obtained from human knee cartilage. Methods:RNA-sequencing (RNA-seq) was performed on 18 normal and 20 OA human knee cartilage tissues. RNA-seq datasets were analysed to identify genes, pathways and regulatory networks that were dysregulated in OA. Results:RNA-seq data analysis revealed 1332 differentially expressed (DE) genes between OA and non-OA samples, including known and novel transcription factors (TFs). Pathway analysis identified 15 significantly perturbed pathways in OA with ECM-related, PI3K-Akt, HIF-1, FoxO and circadian rhythm pathways being the most significantly dysregulated. We selected differentially expressed TFs that are enriched for regulating DE genes in OA and prioritized these transcription factors by creating a cartilage-specific interaction subnetwork. This analysis revealed 8 TFs, including JUN, EGR1, JUND, FOSL2, MYC, KLF4, RELA, and FOS that both target large numbers of dysregulated genes in OA and are themselves suppressed in OA. Conclusion:We identified a novel subnetwork of dysregulated TFs that represent new mediators of abnormal gene expression and promising therapeutic targets in OA.
Project description:Identification of transcription factors responsible for dysregulated networks in human osteoarthritis cartilage by global gene expression analysis
Project description:Osteoarthritis (OA) is the most prevalent joint disease with the typifying feature being the progressive degradation of articular cartilage during disease progression. In this study we used whole transcriptome RNA-seq as a tool to compare gene expression changes between age-matched osteoarthritic human hip OA cartilage (n=10) compared to control (neck of femur fracture) cartilage (n=6) [GSE107308]. All cartilage was from patients undergoing acetabulofemoral joint replacement. Cartilage RNA was isolated from cartilage within 2 hr of joint replacement surgery, mRNA was polyA purified and transcript expression was analysed using 78-base paired-end sequencing generating on average 28 million reads/sample sequencing. The data shows excellent correlation with our previous microarray data but identifies significantly more differentially expressed transcripts plus novel transcript variants, several of which have been validated by real-time qPCR. Our work sheds further light on chondrocyte transcriptome expression and highlights gene expression changes and novel transcripts potentially important in osteoarthritis progression
Project description:Articular cartilage is deprived of blood vessels and nerves, and the only cells residing in this tissue are chondrocytes. The molecular properties of the articular cartilage and the architecture of the extracellular matrix demonstrate a complex structure that differentiates on the depth of tissue. Osteoarthritis (OA) is a degenerative joint disease, the most common form of arthritis, affecting the whole joint. It is associated with ageing and affects the joints that have been continually stressed throughout life including the knees, hips, fingers, and lower spine region. OA is a multifactorial condition of joint characterised by articular cartilage loss, subchondral bone sclerosis, and inflammation leading to progressive joint degradation, structural alterations, loss of mobility and pain. Articular cartilage biology is well studied with a focus on musculoskeletal diseases and cartilage development. However, there are relatively few studies focusing on zonal changes in the cartilage during osteoarthritis.
Project description:Cartilage mineralization is a tightly controlled process, imperative for skeletal growth and fracture repair. However, in osteoarthritis (OA), cartilage mineralization may impact the joint range of motion, inflict pain and may increase chances for joint effusion. Here we attempt to understand the link between inflammation and cartilage mineralization by targeting SIRT1 and LEF1, both reported to have contrasting effects on cartilage.
Project description:Osteoarthritis is characterized by cartilage destruction, chronic inflammation, and subchondral sclerosis. Evidence showed that nuclear receptor family is closely associated with cartilage damage in an unclear molecular mechanism. Here, we investigated the role and molecular mechanism of the retinoic acid receptor-related orphan receptor-α (RORα), an important member of nuclear receptor, in regulating cartilage degradation and osteoarthritis pathogenesis. Investigation to osteoarthritis clinical specimen showed that the degree of RORα elevation is positively correlated with the severity of osteoarthritis and cartilage damage. In an in vivo osteoarthritis models induced by anterior crucial ligament transaction, intraarticularly injection of siRora adenovirus reversed the cartilage damage. RORα knock-down increased the protein expression level of anabolic factor such as type II collagen, Aggrecan, and decreased the expression of catabolic factor. RNA-seq data suggested IL-6/STAT3 pathway is significantly down-regulated. Mechanistically, RORα knock-down decreased the expression level of both IL-6 and phosphorylated STAT3. RORα exerted its effect on IL-6/STAT3 signaling in two different ways, which includes interaction with STAT3 and IL6 promoter. Taken together, our findings indicated the pivotal role of RORα/IL-6/STAT3 axis in osteoarthritis progression and confirmed RORα knock-down exerted therapeutic effect in human chondrocyte thus providing a potential drug target in osteoarthritis therapy.
Project description:Osteoarthritis (OA) is a chronic degenerative disease that leads to joint failure with pain and disability. Gene regulations are implicated in driving an imbalance between the expression of catabolic and anabolic factors, leading eventually to osteoarthritic cartilage degeneration. The different stages of disease progression are described by the complex pattern of transcriptional regulations. The dynamics in pattern alterations were monitored in each individual animal during the time-course of OA progression.