Regulation of mouse chondrocyte differentiation by CCAAT/enhancer-binding proteins.
CCAAT/enhancer-binding protein (C/EBP) β regulates chondrocyte differentiaion and proliferation during endochondral ossification. However, expression and function of other C/EBP family members in chondrocytes have not been fully understood. To understand the comprehensive regulation of chondrocyte differentiation by C/EBPs, we initially examined their expression levels. Among four members (C/EBPα, C/EBPβ, C/EBPδ and C/EBPε) with transactivation domain, expression of Cebpb and Cebpd was abundant compared to Cebpa, while Cebpe was hardly expressed in mouse isolated chondrocytes. Doxycycline (DOX)-inducible overexpression of each of the three C/EBPs (C/EBPα, C/EBPβ and C/EBPδ) in ATDC5 cells suppressed expressions of early differentiation markers including Col2a1, aggrecan and Sox9, enhanced those of late differentiation markers including Mmp13, Vegfa and Col10a1, and decelerated cell proliferation, indicating their overlapped functions in chondrocytes. In contrast, DOX-inducible overexpression of A-CEBP, which exerts a dominant-negative effect against all C/EBPs, increased expressions of early differentiation markers and decreased those of late differentiation markers. Finally, microarray and gene ontology analyses showed that A-CEBP altered many genes related with various events or tissues such as skeletal development, cartilage, cell cycle, inflammation and apoptosis. In conclusion, C/EBPα, C/EBPβ and C/EBPδ regulate proliferation and differentiation of chondrocytes and possibly is involved with apoptosis and inflammation. C/EBPs may play a variety of roles in the homeostasis of joint cartilage under physiological and pathological conditions.
Sensory & Motor System Medicine, Faculty of Medicine, University of Tokyo.
Tomotake
T
Okuma
Makoto
M
Hirata
Fumiko
F
Yano
Daisuke
D
Mori
Hiroshi
H
Kawaguchi
Ung-il
UI
Chung
Sakae
S
Tanaka
Taku
T
Saito
D053674:Aggrecans / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism*; D051743:CCAAT-Enhancer-Binding Protein-delta / Q000235:genetics / Q000378:metabolism*; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002356:Cartilage / Q000166:cytology / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D024121:Collagen Type X / Q000235:genetics / Q000378:metabolism; D004318:Doxycycline / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D053509:Matrix Metalloproteinase 13 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D061251:Primary Cell Culture; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014170:Transformation, Genetic; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
D053674:Aggrecans; D022782:CCAAT-Enhancer-Binding Protein-beta; D022762:CCAAT-Enhancer-Binding Proteins; C530718:CEBPA protein, mouse; C545013:Cebpb protein, mouse; C497253:Cebpd protein, mouse; C489468:Cebpe protein, mouse; C570620:Col10a1 protein, mouse; C447413:Col2a1 protein, mouse; D024043:Collagen Type II; D024121:Collagen Type X; D055758:SOX9 Transcription Factor; C527933:Sox9 protein, mouse; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D051743:CCAAT-Enhancer-Binding Protein-delta; D053509:Matrix Metalloproteinase 13; C507081:Mmp13 protein, mouse; D004318:Doxycycline