Dataset Information

Circadian Rhythm Protein Bmal1 Modulates Cartilage Gene Expression in Temporomandibular Joint Osteoarthritis via the MAPK/ERK Pathway.

ABSTRACT: The purpose of this study was to elucidate the role of the circadian gene Bmal1 in human cartilage and its crosstalk with the MAPK/ERK signaling pathway in temporomandibular joint osteoarthritis (TMJ-OA). We verified the periodical variation of the circadian gene Bmal1 and then established a modified multiple platform method (MMPM) to induce circadian rhythm disturbance leading to TMJ-OA. IL-6, p-ERK, and Bmal1 mRNA and protein expression levels were assessed by real-time RT-PCR and immunohistochemistry. Chondrocytes were treated with an ERK inhibitor (U0126), siRNA and plasmid targeting Bmal1 under IL-6 simulation; then, the cells were subjected to Western blotting to analyze the relationship between Bmal1 and the MAPK/ERK pathway. We found that sleep rhythm disturbance can downregulate the circadian gene BMAL-1 and improve phosphorylated ERK (p-ERK) and IL-6 levels. Furthermore, Bmal1 siRNA transfection was sufficient to improve the p-ERK level and aggravate OA-like gene expression changes under IL-6 stimulation. Bmal1 overexpression relieved the alterations induced by IL-6, which was consistent with the effect of U0126 (an ERK inhibitor). However, we also found that BMAL1 upregulation can decrease ERK phosphorylation, whereas ERK downregulation did not change BMAL1 expression. Collectively, this study provides new insight into the regulatory mechanism that links chondrocyte BMAL1 to cartilage maintenance and repair in TMJ-OA via the MAPK/ERK pathway and suggests that circadian rhythm disruption is a risk factor for TMJ-OA.

SUBMITTER: Chen G

PROVIDER: S-EPMC7530270 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Circadian Rhythm Protein Bmal1 Modulates Cartilage Gene Expression in Temporomandibular Joint Osteoarthritis <i>via</i> the MAPK/ERK Pathway.

Chen Guokun G Zhao Haoming H Ma Shixing S Chen Lei L Wu Gaoyi G Zhu Yong Y Zhu Jie J Ma Chuan C Zhao Huaqiang H

Frontiers in pharmacology 20200918

The purpose of this study was to elucidate the role of the circadian gene Bmal1 in human cartilage and its crosstalk with the MAPK/ERK signaling pathway in temporomandibular joint osteoarthritis (TMJ-OA). We verified the periodical variation of the circadian gene Bmal1 and then established a modified multiple platform method (MMPM) to induce circadian rhythm disturbance leading to TMJ-OA. IL-6, p-ERK, and Bmal1 mRNA and protein expression levels were assessed by real-time RT-PCR and immunohistoc ...[more]

PMID: 33041790

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Project description:BackgroundsAbnormal cartilage calcification is one of the pathological changes of temporomandibular joint (TMJ) osteoarthritis (OA). Recent studies have reported that exosomes can regulate the formation of abnormal calcified nodules in diseases including atherosclerosis and chronic kidney disease. However, the influences of chondrocyte-derived exosomes on abnormal cartilage calcification in TMJ OA are still unclear.MethodsTMJ OA was induced by unilateral anterior crossbite (UAC) for 4, 8, or 12 weeks in rats to observe abnormal calcification in TMJ condylar cartilage and exosome formation. Concomitantly, GW4869, the inhibitor of exosome formation, was locally injected to the TMJ of rats under stimulation of UAC, while the exosomes extracted from primary condylar chondrocytes stimulated with fluid flow shear stress (FFSS) were locally injected to rats TMJ.ResultsAbnormal calcification was enhanced in the degenerative cartilage of TMJ OA in UAC rats, and a large number of exosome-like structures with diameters of 50-150 nm were found in the calcified cartilage together with decreased expression of matrix Gla protein (MGP) and increased expression of CD63, tissue-nonspecific alkaline phosphatase (TNAP) and nucleotide pyrophosphatase/phosphodiesterase-1 (NPP1). After FFSS stimulation, the number of exosomes secreted by chondrocytes and the numbers of calcified nodules were increased in cultured cells, and the protein levels of MGP, TNAP, and NPP1 in exosomes were changed. Inhibition of exosome formation, TNAP, and NPP1 or supplementation with exogenous MGP effectively alleviated FFSS-induced chondrocyte calcification. Local injection of GW4869, the exosome inhibitor, alleviated TMJ OA-related cartilage degeneration and calcification in UAC rats. Local injection of exosomes obtained from chondrocytes stimulated by FFSS to the TMJs of normal rats induced cartilage degeneration and calcification similar to that in TMJ OA.ConclusionsAbnormal biomechanical loading leads to enhanced formation of chondrocyte-derived exosomes, in which promoters of calcification increased and inhibitors decreased, resulting in accelerating abnormal cartilage calcification in TMJ OA. The inhibition of degenerative chondrocyte-derived exosomes is expected to be a new way to prevent and treat TMJ OA.

Project description:Background: Temporomandibular joint osteoarthritis (TMJOA) seriously affects the health of patients, and the current treatments are invasive and only used for advanced cases. Bone marrow mesenchymal stem cell (BMSC)-derived small extracellular vesicles (BMSC-sEVs) may represent a safer and more effective treatment, but their role in TMJOA has not been elucidated. This study attempted to analyze the cartilage reconstruction effect of BMSC-sEVs on TMJOA and the mechanism underlying this effect. Methods: BMSC-sEVs were isolated and purified by microfiltration and ultrafiltration and were subsequently characterized by nanoparticle tracking analysis, electron microscopy, and immunoblotting. TMJOA models were established in vivo and in vitro, and hematoxylin-eosin staining, immunohistochemistry, and histological scoring were performed to analyze the histological changes in TMJOA cartilage tissues treated with BMSC-sEVs. The proliferation, migratory capacity, and cell cycle distribution of TMJOA cartilage cells treated with BMSC-sEVs were detected. Furthermore, the related mechanisms were studied by bioinformatic analysis, immunoblotting, and quantitative PCR, and they were further analyzed by knockdown and inhibitor techniques. Results: The acquisition and identification of BMSC-sEVs were efficient and satisfactory. Compared with the osteoarthritis (OA) group, the condylar tissue of the OA group treated with BMSC-sEV (OAsEV) showed an increase in cartilage lacuna and hypertrophic cartilage cells in the deep area of the bone under the cartilage. Significantly upregulated expression of proliferating cell nuclear antigen and cartilage-forming factors and downregulated expression of cartilage inflammation-related factors in OAsEV were observed. In addition, we found higher rates of cell proliferation and migratory activity and alleviated G1 stagnation of the cell cycle of OAsEV. Autotaxin was found in the BMSC-sEVs, and key factors of the Hippo pathway, Yes-associated protein (YAP), phosphorylated Yes-associated protein (p-YAP), etc. were upregulated in the OAsEV group. Treatment with BMSC-sEVs after autotaxin knockdown or inhibition no longer resulted in expression changes in cartilage-forming and inflammation-related factors and key factors of the Hippo pathway. Conclusions: These results suggest that the autotaxin-YAP signaling axis plays an important role in the mechanism by which BMSC-sEVs promote cartilage reconstruction in TMJOA, which may provide guidance regarding their therapeutic applications as early and minimally invasive therapies for TMJOA, and provide insight into the internal mechanisms of TMJOA.

Dataset Information

Circadian Rhythm Protein Bmal1 Modulates Cartilage Gene Expression in Temporomandibular Joint Osteoarthritis via the MAPK/ERK Pathway.

Publications

Circadian Rhythm Protein Bmal1 Modulates Cartilage Gene Expression in Temporomandibular Joint Osteoarthritis <i>via</i> the MAPK/ERK Pathway.

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