Circ_0008410 contributes to fibroblast-like synoviocytes dysfunction by regulating miR-149-5p/HIPK2 axis.

Circular RNAs (circRNAs) play functional roles in rheumatoid arthritis (RA) progression. Fibroblast-like synoviocytes (RASFs) are the main effectors in RA development. In this study, we explored the function and mechanism of circ_0008410 in RASFs. qRT-PCR was used to detect the expression of circ_0008410, microRNA-149-5p (miR-149-5p), and homeodomain-interacting protein kinase 2 (HIPK2). Cell counting kit-8, EdU assay, flow cytometry, and transwell assay were performed to evaluate cell proliferation, apoptosis, migration, and invasion. Western blot measured the protein levels of related markers and HIPK2. The levels of IL-1ß, TNF-α, and IL-6 were tested by corresponding ELISA kits and Western blot. The combination between miR-149-5p and circ_0008410 or HIPK2 was detected by dual-luciferase reporter assay or RNA immunoprecipitation (RIP) assay. Our data showed that circ_0008410 and HIPK2 were elevated, while miR-149-5p was downregulated in RA synovial tissues and RASFs. Circ_0008410 promoted RASF proliferation, migration, invasion, and inflammation while inhibiting apoptosis. MiR-149-5p was a target of circ_0008410, and its overexpression could reverse the promoting effects of circ_0008410 on RASF dysfunction. Moreover, miR-149-5p could target HIPK2 to suppress RASF proliferation, migration, invasion, and inflammation. Collectively, circ_0008410 promoted RASF dysfunction via miR-149-5p/HIPK2, which might provide a potential target for RA therapy.

Identification of pathways and genes associated with meniscus degeneration using bioinformatics analyses.

OBJECTIVE: To explore the molecular mechanisms underlying meniscus degeneration. METHODS: We performed anterior cruciate ligament resection in the Hainan Wuzhishan pig to establish a meniscus degeneration model. We applied gene chip technology to detect differentially expressed genes (DEG) in the degenerative meniscus tissues. We applied Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, core gene network, and relevant MicroRNA analyses to identify regulatory networks relevant to meniscus degeneration. We detected 893 differentially expressed genes, mainly involved in hormone production, apoptosis, and inflammation. RESULTS: We found that MUC13, inflammatory mediator regulation of TRP channels, MDFI, and miR-335-5p may play a key role in the degenerative meniscus tissue. CONCLUSION: We found that meniscus degeneration involves several molecular mechanisms and provide molecular targets for future research into the disease.

Bioinformatic analysis of the gene expression profile in muscle atrophy after spinal cord injury.

Spinal cord injury (SCI) is often accompanied by muscle atrophy; however, its underlying mechanisms remain unclear. Here, the molecular mechanisms of muscle atrophy following SCI were investigated. The GSE45550 gene expression profile of control (before SCI) and experimental (14 days following SCI) groups, consisting of Sprague-Dawley rat soleus muscle (n = 6 per group), was downloaded from the Gene Expression Omnibus database, and then differentially expressed gene (DEG) identification and Gene Ontology, pathway, pathway network, and gene signal network analyses were performed. A total of 925 differentially expressed genes, 149 biological processes, and 55 pathways were screened. In the pathway network analysis, the 10 most important pathways were citrate cycle (TCA cycle), pyruvate metabolism, MAPK signalling pathway, fatty acid degradation, propanoate metabolism, apoptosis, focal adhesion, synthesis and degradation of ketone bodies, Wnt signalling, and cancer pathways. In the gene signal network analysis, the 10 most important genes were Acat1, Acadvl, Acaa2, Hadhb, Acss1, Oxct1, Hadha, Hadh, Acaca, and Cpt1b. Thus, we screened the key genes and pathways that may be involved in muscle atrophy after SCI and provided support for finding valuable markers for this disease.

LncRNA JPX regulates proliferation and apoptosis of nucleus pulposus cells by targeting the miR-18a-5p/HIF-1α/Hippo-YAP pathway.

With the aggravation of global aging, the rapid rise in the obesity rate, and the increasing number of patients with intervertebral disc degeneration (IDD), the principles and mechanism of this disease remain unclear. This study explored the molecular mechanism of IDD treatment through interactions of the lncRNA-miRNA-mRNA-signaling pathways and the effects on the proliferation and apoptosis of human nucleus pulposus cells (HNPCs) cultured in vitro. Our study revealed that lncRNA JPX is expressed at low levels in HNPCs under normoxic conditions. Luciferase and RNA pull-down assays were used to verify that lncRNA JPX directly bound to miR-18a-5p and influenced HNPC proliferation and apoptosis. Subsequently, a luciferase assay confirmed the direct binding of miR-18a-5p to HIF-1α and demonstrated a negative correlation between miR-18a-5p and HIF-1α. In addition, the HIF-1α antagonist reversed the inhibition of the Hippo-YAP pathway by the miR-18a-5p inhibitor. In conclusion, overexpression of lncRNA JPX upregulated HIF-1α by inhibiting the expression of miR-18a-5p, thereby inhibiting the Hippo-YAP pathway. By inhibiting this pathway, JPX overexpression promoted the proliferation of HNPCs and decreased their apoptosis. Therefore, the lncRNA JPX is a potential new target.

Hypoxia-inducible factor-1α regulates PI3K/AKT signaling through microRNA-32-5p/PTEN and affects nucleus pulposus cell proliferation and apoptosis.

Intervertebral disc degeneration and resulting low back pain arises from the programmed apoptosis of nucleus pulposus cells (NPCs). Recent studies show that hypoxia-inducible factor-1α plays a vital role in the etiology and pathogenesis of disc degeneration. However, the underlying mechanism of HIF-1α in NPCs is unclear. The present study identified 994 significant differentially expressed miRNAs by analyzing microarray data downloaded from the Gene Expression Omnibus database. MicroRNA(miR)-32-5p expression was 2.81-fold upregulated in NPCs compared with that of the healthy control tissues (P<0.05). A total of 331 significant differentially expressed mRNAs were identified, and PTEN was downregulated in NPCs of non-degenerative disc tissues from young patients. miR-32-5p was predicted to target the PTEN 3'-untranslated region (UTR). To confirm these results, in-vitro experiments investigating the molecular function of miR-32-5p and PTEN were performed. Furthermore, hypoxia induced miR-32-5p and PTEN expression. HIF-1α inhibited NPC proliferation and promoted cell apoptosis by regulating miR-32-5p and PTEN. miR-32-5p promoted NPC proliferation and decreased cell apoptosis. Next, it was verified whether miR-32-5p targeted the PTEN 3'-UTR using dual-luciferase reporter assays. Finally, it was observed that PI3K/AKT/mTOR signaling pathway was upregulated by a miR-32-5p mimic, which improved cell proliferation and decreased apoptosis. Importantly, PTEN was downregulated in these experiments; and inhibition of miR-32-5p had the opposite effect. Overall, these results demonstrate that HIF-1α regulates cell proliferation and apoptosis by controlling the miR-32-5p/PTEN/PI3K/AKT/mTOR axis in NPCs.

An animal model study on the gene expression profile of meniscal degeneration.

Meniscal degeneration is a very common condition in elderly individuals, but the underlying mechanisms of its occurrence are not completely clear. This study examines the molecular mechanisms of meniscal degeneration. The anterior cruciate ligament (ACL) and lateral collateral ligament (LCL) of the right rear limbs of seven Wuzhishan mini-pigs were resected (meniscal degeneration group), and the left rear legs were sham-operated (control group). After 6 months, samples were taken for gene chip analysis, including differentially expressed gene (DEG) analysis, gene ontology (GO) analysis, clustering analysis, and pathway analysis. The selected 12 DEGs were validated by real time reverse transcription-polymerase chain reaction (RT-PCR). The two groups showed specific and highly clustered DEGs. A total of 893 DEGs were found, in which 537 are upregulated, and 356 are downregulated. The GO analysis showed that the significantly affected biological processes include nitric oxide metabolic process, male sex differentiation, and mesenchymal morphogenesis, the significantly affected cellular components include the endoplasmic reticulum membrane, and the significantly affected molecular functions include transition metal ion binding and iron ion binding. The pathway analysis showed that the significantly affected pathways include type II diabetes mellitus, inflammatory mediator regulation of TRP channels, and AMPK signaling pathway. The results of RT-PCR indicate that the microarray data accurately reflects the gene expression patterns. These findings indicate that several molecular mechanisms are involved in the development of meniscal degeneration, thus improving our understanding of meniscal degeneration and provide molecular therapeutic targets in the future.

Outcomes of Hip Arthroscopy for Femoroacetabular Impingement in Chinese Patients Aged 50 Years or Older.

OBJECTIVE: To investigate the outcomes of hip arthroscopy for femoroacetabular impingement (FAI) in patients over the age of 50 years. METHOD: This is a therapeutic case series study. A total of 27 FAI patients over the age of 50 years who met inclusion and exclusion criteria and were being followed up for at least 2 years in the orthopaedics department at our hospital between January 2015 and October 2017 were recruited for a prospective analysis on the outcomes of hip arthroscopy. All patients underwent unilateral surgery. Of the patients included, there were 15 men and 12 women, who were aged 50-74 years old (57 ± 6.4 years). The outcomes were assessed using the visual analog scale (VAS), the modified Harris hip score (mHHS), and the International Hip Outcome Tool (iHOT-12). RESULTS: A total of 27 patients were followed up for at least 2 years. The postoperative center-edge angle, the alpha angle, and the offset decreased significantly compared with preoperative measurements (P < 0.01). The mHHS before surgery and at 1 year and 2 years after surgery was 62.19 ± 7.47, 86.70 ± 5.80, and 87.89 ± 5.08, respectively; iHOT-12 scores were 30.44 ± 4.22, 73.56 ± 3.89, and 73.77 ± 3.72, respectively; VAS scores were 6.07 ± 0.78, 1.93 ± 0.73, and 1.59 ± 0.64, respectively. As compared with the condition before surgery, there was a significant improvement in the mHHS, iHOT-12, and VAS scores at 1 year and 2 years after surgery (P < 0.01). The mHHS score at 2-year follow up after surgery was higher than that at 1 year after surgery, and the difference observed was statistically significant (P = 0.04). One patient with severe acetabular and femoral cartilage damage underwent total hip replacement 11 months after surgery. CONCLUSION: Hip arthroscopy considerably improved hip symptoms and function in Chinese FAI patients aged 50 years or older who did not have severe radiographic osteoarthritis. The conversion to THA and complications were low. Strict surgical indications and appropriate surgical strategies lay the foundation for satisfactory postoperative results in elderly patients with FAI.

[Progress on relationship between transforming growth factor-beta1 and tendinopathy].

As a common soft tissue disease, the mechanism of tendinopathy has not been clarified and is lack of effective treatment method. Change of tissue fibrosis is the one of the main pathological features. Transforming growth factor beta 1 (TGF-ß1), which is one of the important factor, participated in fibrosis. Inconsonant expressions of TGF-ß1 could be found in tendinopathy. The studies are still controversial, but the vast majority of studies had showed that TGF-ß1 was abnormal, and it is given priority to increase, which means that TGF-ß1 plays an important role in the process of tendinopathy. In the process of tendon injuries and repairs, the time of TGF-ß1 increasing is inconsistent. The time for TGF-ß1 plays a significant role has not been determined. TGF-ß1 has abnormal expressions in both tendinopathy and tendon repairs, which are two opposite processes. Thus, it may not be a one-way adjustment factor, but has a pleiotropic. Recent studies showed that TGF-ß1 was considered as binding to receptor and transferring signal into the cell. Now there are three different receptors are found. The classical pathway of TGF-ß1 in intracellular signal transduction is mainly through activation of Smad pathway. In the same time, there are also some non-classical pathways. TGF-ß1 could break balance of extracellular matrix, which may be a reason to cause tendinopathy. But the regulations of TGF-ß1 on the extracellular matrix are complex and diverse, further studies are required. Existing researches showed that the performance of treatments on tendinopathy is unsatisfied by blocking TGF-ß1 downstream pathway. Therefore, it is a good way to study the upstream mechanism of produce TGF-ß1. It may be an effective method to find new targets to inhibit the development of tendinopathy better by finding the original source of TGF-ß1.

Identification of pathways and genes associated with synovitis in osteoarthritis using bioinformatics analyses.

Synovitis in osteoarthritis (OA) is a very common condition. However, its underlying mechanism is still not well understood. This study aimed to explore the molecular mechanisms of synovitis in OA. The gene expression profile GSE82107 (downloaded from the Gene Expression Omnibus database) included 10 synovial tissues of the OA patients and 7 synovial tissues of healthy people. Subsequently, differentially expressed gene (DEG) analysis, GO (gene ontology) enrichment analysis, pathway analysis, pathway network analysis, and gene signal network analysis were performed using Gene-Cloud of Biotechnology Information (GCBI). A total of 1,941 DEGs consisting of 1,471 upregulated genes and 470 downregulated genes were determined. Genes such as PSMG3, LRP12 MIA-RAB4B, ETHE1, SFXN1, DAZAP1, RABEP2, and C9orf16 were significantly regulated in synovitis of OA. In particular, the MAPK signalling pathway, apoptosis, and pathways in cancer played the most important roles in the pathway network. The relationships between these pathways were also analysed. Genes such as NRAS, SPHK2, FOS, CXCR4, PLD1, GNAI2, and PLA2G4F were strongly implicated in synovitis of OA. In summary, this study indicated that several molecular mechanisms were implicated in the development and progression of synovitis in OA, thus improving our understanding of OA and offering molecular targets for future therapeutic advances.