Impacts Of Estrogen-related Receptor α Towards Biologic Characteristic Of Rat Mandibular Condyle Chondrocytes

Temporomandibular joint disorder is always going with the abnormal condyle cartilagemetabolism. Condylar chondrocytes has these functions such as to maintain the integrityof the cartilage matrix and to adapt to the environment stimulation. Estrogen plays animportant role in cartilage development, function regulatory and morphology maintenance.Abnormal changes of estrogen can cause condylar cartilage cell proliferation anddifferentiation status change, which may lead to temporomandibular joint disease easily.The estrogen-related receptor alpha (ERRα) is an orphan nuclear receptor (ONR) thatby binding to DNA sites controls gene expression in associatio n with coactivators andcorepressors. ERRα by acting as a transcription factor has been shown to regulate a largearray of genes, thereby controlling numerous metabolic pathways and other biologicalfunctions in animals. The expression of ERRα has been detected in several tissues,including those with high metabolic activities and energy demand.Currently the regulatory function of ERRα in rat mandibular condyle chondrocytes isstill unclear. The research on the role of ERRα in rat condylar cartilage metabolism isconducive to a more profound understanding of the condyle remodeling physiologicalbasis during orthodontic treatment process and the temporomandibular joint disorder development. This may makes ERRα a suitable, direct target for pharmacologicalintervention in treating such diseases.Objective:（1） To investigate the distribution of ERRα expression in female rat condylarcartilage.（2） To investigate the the ERRα expression changes in OVX rat condylarcartilage.（3） To explore the changes of the ERRα expression and biological characteristicsin MCC after estrogen stimulating in vitro.（4） To explore the role of ERRα in MCC regulatory function such as proliferationand differentiation in vitro.Methods：（1） We used density gradient centrifugation combined with adherent wearsmethod to isolate and culture the MCC. Cell phenotypes were identified byusing type II collagen antibody staining and Alcian blue staining.Immunohistochemistry and immunofluorescence staining were used to observethe ERRα expression in MCC and tissues distribution.（2） The changes of the condylar cartilage iconic gene expression and ERRαexpression in OVX rats were observed by Real time RT-PCR analysis.（3） MCC were cultured in vitro stimulation by E2(10-8M). Respectively, MCCwere observed on the the condylar cartilage gene markers and ERRαexpression changes by Real time RT-PCR and Western Blot. Cell proliferationsituation changes was detected by WST-1.（4） MCC were transfected with pcDNA3.1-ERRα for ERRα over-expressed andsynthetic XCT790were used for ERRα inhibition. Real time RT-PCR andWestern Blot analysis were used to observe the condylar cartilage iconicgenes and ERRα expression changes. Results：（1） Cells type II collagen staining and Alcian blue staining, confirmed that thecultured cells were extracted with condylar chondrocyte phenotype.Immunofluorescence and immunohistochemical staining showed condylartissues and cells express ERRα.（2） Real time RT-PCR test results showed that: expression of ERRα、Sox9、GDF-5、Aromatase were decreased1week after OVX and Col2a1had nosignificant change. The expression of ERRα, Sox9and Aromatase wereincreased at8and12weeks after OVX. The expression of GDF-5and Col2a1decreased at8and12weeks after OVX. Cartilage proliferative capacity wereelevated after OVX, but the markers of matural expression of the MCCdropped.（3） WST-1assay showed E2(10-8M) promote MCC proliferation in vitro. Realtime RT-PCR and Western Blot assay showed E2(10-8M) promot all themarkers of proliferation, differentiation and maturation of MCC in vitro.（4） Real time RT-PCR and Western Blot assay showed: ERRα positively regulatesSox9and GDF-5expression. The expression of Aromatase and Col2a1nosignificant change. The ERRα involved in the signal response of thechondrocyte metabolic changes at early stage.Conclusion：（1） ERRα expressed in MCC nucleus and cytoplasm ion. All cartilage layers ofTMJ are distributed.（2） Estrogen deficiency caused by OVX can lead to short-term ERRα expressiondecline, then ERRα expression increased. Estrogen change the expression ofERRα directly or indirectly.（3） Physiological concentrations of estrogen have role in promoting on theproliferation and differentiation of MCC in vitro. ERRα involved in estrogenpromoting MCC proliferation. Estrogen regulate the expression of ERRα by dual effects.（4） ERRα can regulate Sox9and GDF-5expression, and affect the proliferationand differentiation of MCC at early stage.