Author: 〇楊 牧蓁、中村 恵、笹野 泰之
Affiliation: 東北大 院歯 顎口腔組織発生
Abstract:
Purpose: The temporomandibular joint (TMJ) has been reported to deform the morphology with aging. The surface of the TMJ condyle is covered with fibrocartilage consisting of chondrocytes and extracellular matrix (ECM) such as collagen type I, collagen type II and proteoglycans. Matrix metalloproteinases (MMPs) are the major ECM proteases that contribute to ECM remodeling by degrading collagens and proteoglycans. However, few studies have focused on the role of MMPs in the aged TMJ. The purpose of this study is to identify up-regulated and down-regulated genes encoding MMPs by whole transcriptome analysis and to investigate the distribution of corresponding translated proteins by immunohistochemistry in the TMJ of aged mice. Materials & Methods: 10-week-old and 50-week-old male C57BL/6 mice were used. Total RNA was extracted from the TMJ and cap analysis of gene expression (CAGE) was performed for whole transcriptome analysis. Based on the CAGE data, gene ontology (GO) analysis was performed by Metascape. In addition, TMJ samples were fixed with paraformaldehyde, decalcified with EDTA and embedded in paraffin. Serial sections were cut and used for immunohistochemistry. Results & Conclusion: CAGE analysis showed that the gene expression of MMP-3 was up-regulated while those of MMP-9 and MMP-13 were down-regulated in the TMJ of 50-week-old mice. GO analysis also showed that the most enriched gene group was the extracellular matrix organization, including MMPs-3, -9 and -13. MMP-9 immunoreactivity was localized in multinucleated cells at the bone-cartilage interface of condyle. MMP-13 protein was mainly expressed in the hypertrophic layer of TMJ condyle, and MMP-3 protein was expressed in all layers except for the hypertrophic layer. Our results demonstrated that MMP-3 gene is up-regulated, and MMP-9 and MMP-13 genes are down-regulated in the TMJ of 50-week-old mice, and these MMPs have different localization in the TMJ condyle.
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