Dataset Information

Expression data of wild type and DDR-1-KO mice TMJ-cartilage

ABSTRACT: The discoidin domain receptor 1 (DDR-1) deficient mice exhibit a high incidence of osteoarthritis (OA) in the temporomandibular joint (TMJ) already at early age. Young DDR-1 knock-out mice show typical histological signs of OA, like, surface fissures, loss of proteoglycans, cluster formation of the chondrocytes, altered collagen types as well as atypical arrangement of the collagen fibrils. The isolated chondrocytes from the TMJ exhibit an osteoarthritic character with high amounts of Runt-related transcription factor 2 (runx-2) and collagen type I compared to low levels of SRY (sex determining region Y)-box 9 (sox-9) and aggrecan. Especially, the amount of discoidin domain receptor 2 (DDR2) is increased, which is key player of OA in this model. The gene expression as well as the proteins of the DDR-1-deficient chondrocytes from the TMJ could be influenced by a three dimensional matrix, combined with a knockdown of runx-2 or the stimulation with components of the extracellular matrix, for example nidogen-2. These manipulations caused the osteoarthritic chondrocytes of DDR-1-deficient mice to change their gene expression towards a signature of more physiological cartilage and will open new possibilities for future regenerative treatment options of temporomandibular disorders like OA of the TMJ.

ORGANISM(S): Mus musculus

PROVIDER: GSE35297 | GEO | 2012/01/25

SECONDARY ACCESSION(S): PRJNA151603

REPOSITORIES: GEO

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Project description:Background Extracellular matrix (ECM) protein malfunction or defect may lead to temporomandibular joint osteoarthritis (TMJ OA). Dentin sialophophoprotein (DSPP) is a mandibular condylar cartilage ECM protein, and its deletion impacted cell proliferation and other extracellular matrix alterations of postnatal condylar cartilage. However, it remains unclear if long-term loss of function of DSPP leads to TMJ OA. The study aimed to test the hypothesis that long-term haploinsufficiency of DSPP causes TMJ OA. Materials and Methods To determine whether Dspp+/- mice exhibit TMJ OA but no severe tooth defects, mandibles of wild-type (WT), Dspp+/-, and Dspp homozygous (Dspp-/-) mice were analyzed by Micro-computed tomography (micro-CT). To characterize the progression and possible mechanisms of osteoarthritic degeneration over time in Dspp+/- mice over time, condyles of Dspp+/- and WT mice were analyzed radiologically, histologically, and immunohistochemically. Results Micro-CT and histomorphometric analyses revealed that Dspp+/- and Dspp-/- mice had significantly lower subchondral bone mass, bone volume fraction, bone mineral density, and trabecular thickness compared to WT mice at 12 months. Interestingly, in contrast to Dspp-/- mice which exhibited tooth loss, Dspp+/- mice had minor tooth defects. RNA sequencing data showed that haplodeficency of DSPP affects the biological process of ossification and osteoclast differentiation. Additionally, histological analysis showed that Dspp+/- mice had condylar cartilage fissures, reduced cartilage thickness, decreased articular cell numbers and severe subchondral bone cavities, and with signs that were exaggerated with age. Radiographic data showed an increase in subchondral osteoporosis up to 18 months and osteophyte formation at 21 months. Moreover, Dspp+/- mice showed increased distribution of osteoclast in the subchondal bone and increased expression of MMP2, IL-6, FN-1, and TLR4 in the mandibular condylar cartilage. Conclusions Dspp+/- mice exhibit TMJ OA in a time-dependent manner, with lesions in the mandibular condyle attributed to hypomineralization of subchondral bone and breakdown of the mandibular condylar cartilage, accompanied by upregulation of inflammatory markers.