title: Zbtb20 regulates the terminal differentiation of hypertrophic chondrocytes via repression of Sox9.
abstract: The terminal differentiation of hypertrophic chondrocytes is a tightly regulated process that plays a pivotal role in endochondral ossification. As a negative regulator, Sox9 is essentially downregulated in terminally differentiated hypertrophic chondrocytes. However, the underlying mechanism of Sox9 silencing is undefined. Here we show that the zinc finger protein Zbtb20 regulates the terminal differentiation of hypertrophic chondrocytes by repressing Sox9. In the developing skeleton of the mouse, Zbtb20 protein is highly expressed by hypertrophic chondrocytes from late embryonic stages. To determine its physiological role in endochondral ossification, we have generated chondrocyte-specific Zbtb20 knockout mice and demonstrate that disruption of Zbtb20 in chondrocytes results in delayed endochondral ossification and postnatal growth retardation. Zbtb20 deficiency caused a delay in cartilage vascularization and an expansion of the hypertrophic zone owing to reduced expression of Vegfa in the hypertrophic zone. Interestingly, Sox9, a direct suppressor of Vegfa expression, was ectopically upregulated at both mRNA and protein levels in the late Zbtb20-deficient hypertrophic zone. Furthermore, knockdown of Sox9 greatly increased Vegfa expression in Zbtb20-deficient hypertrophic chondrocytes. Our findings point to Zbtb20 as a crucial regulator governing the terminal differentiation of hypertrophic chondrocytes at least partially through repression of Sox9.
authors.affiliation: Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Guangdi
authors.initials: G
authors.lastname: Zhou
authors.affiliation: Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Xuchao
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Hai
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Yinzhong
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China Department of Cell Biology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Anjun
authors.initials: A
authors.lastname: Liu
authors.affiliation: Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Xianhua
authors.initials: X
authors.lastname: Ma
authors.affiliation: Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing 100071, China.
authors.forename: Guan
authors.initials: G
authors.lastname: Yang
authors.affiliation: Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Yang
authors.affiliation: Department of Orthopedics, Changhai Hospital, Shanghai 200433, China.
authors.forename: Hongxing
authors.initials: H
authors.lastname: Shen
authors.affiliation: Department of Pathology, Changhai Hospital, Shanghai 200433, China.
authors.forename: Jianming
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Department of Cell Biology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Genetic Laboratory of Development and Diseases, Institute of Biotechnology, Beijing 100071, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China wzhang@smmu.edu.cn xiezf@smmu.edu.cn.
authors.forename: Weiping J
authors.initials: WJ
authors.lastname: Zhang
authors.affiliation: Department of Pathophysiology, Second Military Medical University, Shanghai 200433, China Department of Cell Biology, Second Military Medical University, Shanghai 200433, China wzhang@smmu.edu.cn xiezf@smmu.edu.cn.
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Xie
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D019902:Chondrocytes / Q000502:physiology*; D047369:Chromatin Immunoprecipitation; D006652:Histological Techniques; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D018345:Mice, Knockout; D010012:Osteogenesis / Q000502:physiology*; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055758:SOX9 Transcription Factor / Q000037:antagonists & inhibitors* / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D055758:SOX9 Transcription Factor; C527933:Sox9 protein, mouse; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; C520426:Zbtb20 protein, mouse; C467480:vascular endothelial growth factor A, mouse
keywords: Bone development; Hypertrophic chondrocyte; Sox9; Terminal differentiation; Transcription factor